4438 lines
122 KiB
C
4438 lines
122 KiB
C
/*
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* pcap-linux.c: Packet capture interface to the Linux kernel
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*
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* Copyright (c) 2000 Torsten Landschoff <torsten@debian.org>
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* Sebastian Krahmer <krahmer@cs.uni-potsdam.de>
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*
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* License: BSD
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. The names of the authors may not be used to endorse or promote
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* products derived from this software without specific prior
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* written permission.
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*
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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*
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* Modifications: Added PACKET_MMAP support
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* Paolo Abeni <paolo.abeni@email.it>
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*
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* based on previous works of:
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* Simon Patarin <patarin@cs.unibo.it>
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* Phil Wood <cpw@lanl.gov>
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*
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* Monitor-mode support for mac80211 includes code taken from the iw
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* command; the copyright notice for that code is
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*
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* Copyright (c) 2007, 2008 Johannes Berg
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* Copyright (c) 2007 Andy Lutomirski
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* Copyright (c) 2007 Mike Kershaw
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* Copyright (c) 2008 Gábor Stefanik
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*
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#ifndef lint
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static const char rcsid[] _U_ =
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"@(#) $Header: /tcpdump/master/libpcap/pcap-linux.c,v 1.164 2008-12-14 22:00:57 guy Exp $ (LBL)";
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#endif
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/*
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* Known problems with 2.0[.x] kernels:
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*
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* - The loopback device gives every packet twice; on 2.2[.x] kernels,
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* if we use PF_PACKET, we can filter out the transmitted version
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* of the packet by using data in the "sockaddr_ll" returned by
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* "recvfrom()", but, on 2.0[.x] kernels, we have to use
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* PF_INET/SOCK_PACKET, which means "recvfrom()" supplies a
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* "sockaddr_pkt" which doesn't give us enough information to let
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* us do that.
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*
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* - We have to set the interface's IFF_PROMISC flag ourselves, if
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* we're to run in promiscuous mode, which means we have to turn
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* it off ourselves when we're done; the kernel doesn't keep track
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* of how many sockets are listening promiscuously, which means
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* it won't get turned off automatically when no sockets are
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* listening promiscuously. We catch "pcap_close()" and, for
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* interfaces we put into promiscuous mode, take them out of
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* promiscuous mode - which isn't necessarily the right thing to
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* do, if another socket also requested promiscuous mode between
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* the time when we opened the socket and the time when we close
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* the socket.
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*
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* - MSG_TRUNC isn't supported, so you can't specify that "recvfrom()"
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* return the amount of data that you could have read, rather than
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* the amount that was returned, so we can't just allocate a buffer
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* whose size is the snapshot length and pass the snapshot length
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* as the byte count, and also pass MSG_TRUNC, so that the return
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* value tells us how long the packet was on the wire.
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*
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* This means that, if we want to get the actual size of the packet,
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* so we can return it in the "len" field of the packet header,
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* we have to read the entire packet, not just the part that fits
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* within the snapshot length, and thus waste CPU time copying data
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* from the kernel that our caller won't see.
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*
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* We have to get the actual size, and supply it in "len", because
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* otherwise, the IP dissector in tcpdump, for example, will complain
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* about "truncated-ip", as the packet will appear to have been
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* shorter, on the wire, than the IP header said it should have been.
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*/
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#define _GNU_SOURCE
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <string.h>
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#include <limits.h>
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#include <sys/socket.h>
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#include <sys/ioctl.h>
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#include <sys/utsname.h>
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#include <sys/mman.h>
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#include <linux/if.h>
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#include <netinet/in.h>
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#include <linux/if_ether.h>
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#include <net/if_arp.h>
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#include <poll.h>
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/*
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* Got Wireless Extensions?
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*/
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#ifdef HAVE_LINUX_WIRELESS_H
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#include <linux/wireless.h>
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#endif /* HAVE_LINUX_WIRELESS_H */
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/*
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* Got libnl?
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*/
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#ifdef HAVE_LIBNL
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#include <linux/nl80211.h>
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#include <netlink/genl/genl.h>
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#include <netlink/genl/family.h>
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#include <netlink/genl/ctrl.h>
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#include <netlink/msg.h>
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#include <netlink/attr.h>
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#endif /* HAVE_LIBNL */
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#include "pcap-int.h"
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#include "pcap/sll.h"
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#include "pcap/vlan.h"
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#ifdef HAVE_DAG_API
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#include "pcap-dag.h"
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#endif /* HAVE_DAG_API */
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#ifdef HAVE_SEPTEL_API
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#include "pcap-septel.h"
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#endif /* HAVE_SEPTEL_API */
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#ifdef PCAP_SUPPORT_USB
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#include "pcap-usb-linux.h"
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#endif
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#ifdef PCAP_SUPPORT_BT
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#include "pcap-bt-linux.h"
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#endif
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/*
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* If PF_PACKET is defined, we can use {SOCK_RAW,SOCK_DGRAM}/PF_PACKET
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* sockets rather than SOCK_PACKET sockets.
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*
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* To use them, we include <linux/if_packet.h> rather than
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* <netpacket/packet.h>; we do so because
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*
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* some Linux distributions (e.g., Slackware 4.0) have 2.2 or
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* later kernels and libc5, and don't provide a <netpacket/packet.h>
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* file;
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*
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* not all versions of glibc2 have a <netpacket/packet.h> file
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* that defines stuff needed for some of the 2.4-or-later-kernel
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* features, so if the system has a 2.4 or later kernel, we
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* still can't use those features.
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*
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* We're already including a number of other <linux/XXX.h> headers, and
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* this code is Linux-specific (no other OS has PF_PACKET sockets as
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* a raw packet capture mechanism), so it's not as if you gain any
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* useful portability by using <netpacket/packet.h>
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*
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* XXX - should we just include <linux/if_packet.h> even if PF_PACKET
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* isn't defined? It only defines one data structure in 2.0.x, so
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* it shouldn't cause any problems.
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*/
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#ifdef PF_PACKET
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# include <linux/if_packet.h>
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/*
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* On at least some Linux distributions (for example, Red Hat 5.2),
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* there's no <netpacket/packet.h> file, but PF_PACKET is defined if
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* you include <sys/socket.h>, but <linux/if_packet.h> doesn't define
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* any of the PF_PACKET stuff such as "struct sockaddr_ll" or any of
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* the PACKET_xxx stuff.
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*
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* So we check whether PACKET_HOST is defined, and assume that we have
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* PF_PACKET sockets only if it is defined.
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*/
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# ifdef PACKET_HOST
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# define HAVE_PF_PACKET_SOCKETS
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# ifdef PACKET_AUXDATA
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# define HAVE_PACKET_AUXDATA
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# endif /* PACKET_AUXDATA */
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# endif /* PACKET_HOST */
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/* check for memory mapped access avaibility. We assume every needed
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* struct is defined if the macro TPACKET_HDRLEN is defined, because it
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* uses many ring related structs and macros */
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# ifdef TPACKET_HDRLEN
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# define HAVE_PACKET_RING
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# ifdef TPACKET2_HDRLEN
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# define HAVE_TPACKET2
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# else
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# define TPACKET_V1 0
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# endif /* TPACKET2_HDRLEN */
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# endif /* TPACKET_HDRLEN */
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#endif /* PF_PACKET */
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#ifdef SO_ATTACH_FILTER
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#include <linux/types.h>
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#include <linux/filter.h>
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#endif
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#ifndef HAVE_SOCKLEN_T
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typedef int socklen_t;
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#endif
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#ifndef MSG_TRUNC
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/*
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* This is being compiled on a system that lacks MSG_TRUNC; define it
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* with the value it has in the 2.2 and later kernels, so that, on
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* those kernels, when we pass it in the flags argument to "recvfrom()"
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* we're passing the right value and thus get the MSG_TRUNC behavior
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* we want. (We don't get that behavior on 2.0[.x] kernels, because
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* they didn't support MSG_TRUNC.)
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*/
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#define MSG_TRUNC 0x20
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#endif
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#ifndef SOL_PACKET
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/*
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* This is being compiled on a system that lacks SOL_PACKET; define it
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* with the value it has in the 2.2 and later kernels, so that we can
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* set promiscuous mode in the good modern way rather than the old
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* 2.0-kernel crappy way.
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*/
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#define SOL_PACKET 263
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#endif
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#define MAX_LINKHEADER_SIZE 256
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/*
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* When capturing on all interfaces we use this as the buffer size.
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* Should be bigger then all MTUs that occur in real life.
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* 64kB should be enough for now.
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*/
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#define BIGGER_THAN_ALL_MTUS (64*1024)
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/*
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* Prototypes for internal functions and methods.
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*/
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static void map_arphrd_to_dlt(pcap_t *, int, int);
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#ifdef HAVE_PF_PACKET_SOCKETS
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static short int map_packet_type_to_sll_type(short int);
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#endif
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static int pcap_activate_linux(pcap_t *);
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static int activate_old(pcap_t *);
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static int activate_new(pcap_t *);
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static int activate_mmap(pcap_t *);
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static int pcap_can_set_rfmon_linux(pcap_t *);
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static int pcap_read_linux(pcap_t *, int, pcap_handler, u_char *);
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static int pcap_read_packet(pcap_t *, pcap_handler, u_char *);
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static int pcap_inject_linux(pcap_t *, const void *, size_t);
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static int pcap_stats_linux(pcap_t *, struct pcap_stat *);
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static int pcap_setfilter_linux(pcap_t *, struct bpf_program *);
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static int pcap_setdirection_linux(pcap_t *, pcap_direction_t);
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static void pcap_cleanup_linux(pcap_t *);
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union thdr {
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struct tpacket_hdr *h1;
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struct tpacket2_hdr *h2;
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void *raw;
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};
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#ifdef HAVE_PACKET_RING
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#define RING_GET_FRAME(h) (((union thdr **)h->buffer)[h->offset])
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static void destroy_ring(pcap_t *handle);
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static int create_ring(pcap_t *handle);
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static int prepare_tpacket_socket(pcap_t *handle);
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static void pcap_cleanup_linux_mmap(pcap_t *);
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static int pcap_read_linux_mmap(pcap_t *, int, pcap_handler , u_char *);
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static int pcap_setfilter_linux_mmap(pcap_t *, struct bpf_program *);
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static int pcap_setnonblock_mmap(pcap_t *p, int nonblock, char *errbuf);
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static int pcap_getnonblock_mmap(pcap_t *p, char *errbuf);
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static void pcap_oneshot_mmap(u_char *user, const struct pcap_pkthdr *h,
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const u_char *bytes);
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#endif
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/*
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* Wrap some ioctl calls
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*/
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#ifdef HAVE_PF_PACKET_SOCKETS
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static int iface_get_id(int fd, const char *device, char *ebuf);
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#endif
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static int iface_get_mtu(int fd, const char *device, char *ebuf);
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static int iface_get_arptype(int fd, const char *device, char *ebuf);
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#ifdef HAVE_PF_PACKET_SOCKETS
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static int iface_bind(int fd, int ifindex, char *ebuf);
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#ifdef IW_MODE_MONITOR
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static int has_wext(int sock_fd, const char *device, char *ebuf);
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#endif /* IW_MODE_MONITOR */
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static int enter_rfmon_mode(pcap_t *handle, int sock_fd,
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const char *device);
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#endif /* HAVE_PF_PACKET_SOCKETS */
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static int iface_bind_old(int fd, const char *device, char *ebuf);
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#ifdef SO_ATTACH_FILTER
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static int fix_program(pcap_t *handle, struct sock_fprog *fcode,
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int is_mapped);
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static int fix_offset(struct bpf_insn *p);
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static int set_kernel_filter(pcap_t *handle, struct sock_fprog *fcode);
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static int reset_kernel_filter(pcap_t *handle);
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static struct sock_filter total_insn
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= BPF_STMT(BPF_RET | BPF_K, 0);
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static struct sock_fprog total_fcode
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= { 1, &total_insn };
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#endif
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pcap_t *
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pcap_create(const char *device, char *ebuf)
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{
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pcap_t *handle;
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/*
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* A null device name is equivalent to the "any" device.
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*/
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if (device == NULL)
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device = "any";
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#ifdef HAVE_DAG_API
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if (strstr(device, "dag")) {
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return dag_create(device, ebuf);
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}
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#endif /* HAVE_DAG_API */
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#ifdef HAVE_SEPTEL_API
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if (strstr(device, "septel")) {
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return septel_create(device, ebuf);
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}
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#endif /* HAVE_SEPTEL_API */
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#ifdef PCAP_SUPPORT_BT
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if (strstr(device, "bluetooth")) {
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return bt_create(device, ebuf);
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}
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#endif
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#ifdef PCAP_SUPPORT_USB
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if (strstr(device, "usbmon")) {
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return usb_create(device, ebuf);
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}
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#endif
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handle = pcap_create_common(device, ebuf);
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if (handle == NULL)
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return NULL;
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handle->activate_op = pcap_activate_linux;
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handle->can_set_rfmon_op = pcap_can_set_rfmon_linux;
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return handle;
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}
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#ifdef HAVE_LIBNL
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/*
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*
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* If interface {if} is a mac80211 driver, the file
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* /sys/class/net/{if}/phy80211 is a symlink to
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* /sys/class/ieee80211/{phydev}, for some {phydev}.
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*
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* On Fedora 9, with a 2.6.26.3-29 kernel, my Zydas stick, at
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* least, has a "wmaster0" device and a "wlan0" device; the
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* latter is the one with the IP address. Both show up in
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* "tcpdump -D" output. Capturing on the wmaster0 device
|
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* captures with 802.11 headers.
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*
|
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* airmon-ng searches through /sys/class/net for devices named
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* monN, starting with mon0; as soon as one *doesn't* exist,
|
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* it chooses that as the monitor device name. If the "iw"
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* command exists, it does "iw dev {if} interface add {monif}
|
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* type monitor", where {monif} is the monitor device. It
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* then (sigh) sleeps .1 second, and then configures the
|
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* device up. Otherwise, if /sys/class/ieee80211/{phydev}/add_iface
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* is a file, it writes {mondev}, without a newline, to that file,
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* and again (sigh) sleeps .1 second, and then iwconfig's that
|
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* device into monitor mode and configures it up. Otherwise,
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* you can't do monitor mode.
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*
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* All these devices are "glued" together by having the
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* /sys/class/net/{device}/phy80211 links pointing to the same
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* place, so, given a wmaster, wlan, or mon device, you can
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* find the other devices by looking for devices with
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* the same phy80211 link.
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*
|
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* To turn monitor mode off, delete the monitor interface,
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* either with "iw dev {monif} interface del" or by sending
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* {monif}, with no NL, down /sys/class/ieee80211/{phydev}/remove_iface
|
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*
|
|
* Note: if you try to create a monitor device named "monN", and
|
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* there's already a "monN" device, it fails, as least with
|
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* the netlink interface (which is what iw uses), with a return
|
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* value of -ENFILE. (Return values are negative errnos.) We
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* could probably use that to find an unused device.
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*
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* Yes, you can have multiple monitor devices for a given
|
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* physical device.
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*/
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|
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/*
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* Is this a mac80211 device? If so, fill in the physical device path and
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* return 1; if not, return 0. On an error, fill in handle->errbuf and
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* return PCAP_ERROR.
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*/
|
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static int
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get_mac80211_phydev(pcap_t *handle, const char *device, char *phydev_path,
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size_t phydev_max_pathlen)
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{
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char *pathstr;
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ssize_t bytes_read;
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|
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/*
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* Generate the path string for the symlink to the physical device.
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*/
|
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if (asprintf(&pathstr, "/sys/class/net/%s/phy80211", device) == -1) {
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snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
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"%s: Can't generate path name string for /sys/class/net device",
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device);
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return PCAP_ERROR;
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}
|
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bytes_read = readlink(pathstr, phydev_path, phydev_max_pathlen);
|
|
if (bytes_read == -1) {
|
|
if (errno == ENOENT || errno == EINVAL) {
|
|
/*
|
|
* Doesn't exist, or not a symlink; assume that
|
|
* means it's not a mac80211 device.
|
|
*/
|
|
free(pathstr);
|
|
return 0;
|
|
}
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"%s: Can't readlink %s: %s", device, pathstr,
|
|
strerror(errno));
|
|
free(pathstr);
|
|
return PCAP_ERROR;
|
|
}
|
|
free(pathstr);
|
|
phydev_path[bytes_read] = '\0';
|
|
return 1;
|
|
}
|
|
|
|
struct nl80211_state {
|
|
struct nl_handle *nl_handle;
|
|
struct nl_cache *nl_cache;
|
|
struct genl_family *nl80211;
|
|
};
|
|
|
|
static int
|
|
nl80211_init(pcap_t *handle, struct nl80211_state *state, const char *device)
|
|
{
|
|
state->nl_handle = nl_handle_alloc();
|
|
if (!state->nl_handle) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"%s: failed to allocate netlink handle", device);
|
|
return PCAP_ERROR;
|
|
}
|
|
|
|
if (genl_connect(state->nl_handle)) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"%s: failed to connect to generic netlink", device);
|
|
goto out_handle_destroy;
|
|
}
|
|
|
|
state->nl_cache = genl_ctrl_alloc_cache(state->nl_handle);
|
|
if (!state->nl_cache) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"%s: failed to allocate generic netlink cache", device);
|
|
goto out_handle_destroy;
|
|
}
|
|
|
|
state->nl80211 = genl_ctrl_search_by_name(state->nl_cache, "nl80211");
|
|
if (!state->nl80211) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"%s: nl80211 not found", device);
|
|
goto out_cache_free;
|
|
}
|
|
|
|
return 0;
|
|
|
|
out_cache_free:
|
|
nl_cache_free(state->nl_cache);
|
|
out_handle_destroy:
|
|
nl_handle_destroy(state->nl_handle);
|
|
return PCAP_ERROR;
|
|
}
|
|
|
|
static void
|
|
nl80211_cleanup(struct nl80211_state *state)
|
|
{
|
|
genl_family_put(state->nl80211);
|
|
nl_cache_free(state->nl_cache);
|
|
nl_handle_destroy(state->nl_handle);
|
|
}
|
|
|
|
static int
|
|
add_mon_if(pcap_t *handle, int sock_fd, struct nl80211_state *state,
|
|
const char *device, const char *mondevice)
|
|
{
|
|
int ifindex;
|
|
struct nl_msg *msg;
|
|
int err;
|
|
|
|
ifindex = iface_get_id(sock_fd, device, handle->errbuf);
|
|
if (ifindex == -1)
|
|
return PCAP_ERROR;
|
|
|
|
msg = nlmsg_alloc();
|
|
if (!msg) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"%s: failed to allocate netlink msg", device);
|
|
return PCAP_ERROR;
|
|
}
|
|
|
|
genlmsg_put(msg, 0, 0, genl_family_get_id(state->nl80211), 0,
|
|
0, NL80211_CMD_NEW_INTERFACE, 0);
|
|
NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, ifindex);
|
|
NLA_PUT_STRING(msg, NL80211_ATTR_IFNAME, mondevice);
|
|
NLA_PUT_U32(msg, NL80211_ATTR_IFTYPE, NL80211_IFTYPE_MONITOR);
|
|
|
|
err = nl_send_auto_complete(state->nl_handle, msg);
|
|
if (err < 0) {
|
|
if (err == -ENFILE) {
|
|
/*
|
|
* Device not available; our caller should just
|
|
* keep trying.
|
|
*/
|
|
nlmsg_free(msg);
|
|
return 0;
|
|
} else {
|
|
/*
|
|
* Real failure, not just "that device is not
|
|
* available.
|
|
*/
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"%s: nl_send_auto_complete failed adding %s interface: %s",
|
|
device, mondevice, strerror(-err));
|
|
nlmsg_free(msg);
|
|
return PCAP_ERROR;
|
|
}
|
|
}
|
|
err = nl_wait_for_ack(state->nl_handle);
|
|
if (err < 0) {
|
|
if (err == -ENFILE) {
|
|
/*
|
|
* Device not available; our caller should just
|
|
* keep trying.
|
|
*/
|
|
nlmsg_free(msg);
|
|
return 0;
|
|
} else {
|
|
/*
|
|
* Real failure, not just "that device is not
|
|
* available.
|
|
*/
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"%s: nl_wait_for_ack failed adding %s interface: %s",
|
|
device, mondevice, strerror(-err));
|
|
nlmsg_free(msg);
|
|
return PCAP_ERROR;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Success.
|
|
*/
|
|
nlmsg_free(msg);
|
|
return 1;
|
|
|
|
nla_put_failure:
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"%s: nl_put failed adding %s interface",
|
|
device, mondevice);
|
|
nlmsg_free(msg);
|
|
return PCAP_ERROR;
|
|
}
|
|
|
|
static int
|
|
del_mon_if(pcap_t *handle, int sock_fd, struct nl80211_state *state,
|
|
const char *device, const char *mondevice)
|
|
{
|
|
int ifindex;
|
|
struct nl_msg *msg;
|
|
int err;
|
|
|
|
ifindex = iface_get_id(sock_fd, mondevice, handle->errbuf);
|
|
if (ifindex == -1)
|
|
return PCAP_ERROR;
|
|
|
|
msg = nlmsg_alloc();
|
|
if (!msg) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"%s: failed to allocate netlink msg", device);
|
|
return PCAP_ERROR;
|
|
}
|
|
|
|
genlmsg_put(msg, 0, 0, genl_family_get_id(state->nl80211), 0,
|
|
0, NL80211_CMD_DEL_INTERFACE, 0);
|
|
NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, ifindex);
|
|
|
|
err = nl_send_auto_complete(state->nl_handle, msg);
|
|
if (err < 0) {
|
|
if (err == -ENFILE) {
|
|
/*
|
|
* Device not available; our caller should just
|
|
* keep trying.
|
|
*/
|
|
nlmsg_free(msg);
|
|
return 0;
|
|
} else {
|
|
/*
|
|
* Real failure, not just "that device is not
|
|
* available.
|
|
*/
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"%s: nl_send_auto_complete failed deleting %s interface: %s",
|
|
device, mondevice, strerror(-err));
|
|
nlmsg_free(msg);
|
|
return PCAP_ERROR;
|
|
}
|
|
}
|
|
err = nl_wait_for_ack(state->nl_handle);
|
|
if (err < 0) {
|
|
if (err == -ENFILE) {
|
|
/*
|
|
* Device not available; our caller should just
|
|
* keep trying.
|
|
*/
|
|
nlmsg_free(msg);
|
|
return 0;
|
|
} else {
|
|
/*
|
|
* Real failure, not just "that device is not
|
|
* available.
|
|
*/
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"%s: nl_wait_for_ack failed adding %s interface: %s",
|
|
device, mondevice, strerror(-err));
|
|
nlmsg_free(msg);
|
|
return PCAP_ERROR;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Success.
|
|
*/
|
|
nlmsg_free(msg);
|
|
return 1;
|
|
|
|
nla_put_failure:
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"%s: nl_put failed deleting %s interface",
|
|
device, mondevice);
|
|
nlmsg_free(msg);
|
|
return PCAP_ERROR;
|
|
}
|
|
|
|
static int
|
|
enter_rfmon_mode_mac80211(pcap_t *handle, int sock_fd, const char *device)
|
|
{
|
|
int ret;
|
|
char phydev_path[PATH_MAX+1];
|
|
struct nl80211_state nlstate;
|
|
struct ifreq ifr;
|
|
u_int n;
|
|
|
|
/*
|
|
* Is this a mac80211 device?
|
|
*/
|
|
ret = get_mac80211_phydev(handle, device, phydev_path, PATH_MAX);
|
|
if (ret < 0)
|
|
return ret; /* error */
|
|
if (ret == 0)
|
|
return 0; /* no error, but not mac80211 device */
|
|
|
|
/*
|
|
* XXX - is this already a monN device?
|
|
* If so, we're done.
|
|
* Is that determined by old Wireless Extensions ioctls?
|
|
*/
|
|
|
|
/*
|
|
* OK, it's apparently a mac80211 device.
|
|
* Try to find an unused monN device for it.
|
|
*/
|
|
ret = nl80211_init(handle, &nlstate, device);
|
|
if (ret != 0)
|
|
return ret;
|
|
for (n = 0; n < UINT_MAX; n++) {
|
|
/*
|
|
* Try mon{n}.
|
|
*/
|
|
char mondevice[3+10+1]; /* mon{UINT_MAX}\0 */
|
|
|
|
snprintf(mondevice, sizeof mondevice, "mon%u", n);
|
|
ret = add_mon_if(handle, sock_fd, &nlstate, device, mondevice);
|
|
if (ret == 1) {
|
|
handle->md.mondevice = strdup(mondevice);
|
|
goto added;
|
|
}
|
|
if (ret < 0) {
|
|
/*
|
|
* Hard failure. Just return ret; handle->errbuf
|
|
* has already been set.
|
|
*/
|
|
nl80211_cleanup(&nlstate);
|
|
return ret;
|
|
}
|
|
}
|
|
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"%s: No free monN interfaces", device);
|
|
nl80211_cleanup(&nlstate);
|
|
return PCAP_ERROR;
|
|
|
|
added:
|
|
|
|
#if 0
|
|
/*
|
|
* Sleep for .1 seconds.
|
|
*/
|
|
delay.tv_sec = 0;
|
|
delay.tv_nsec = 500000000;
|
|
nanosleep(&delay, NULL);
|
|
#endif
|
|
|
|
/*
|
|
* Now configure the monitor interface up.
|
|
*/
|
|
memset(&ifr, 0, sizeof(ifr));
|
|
strncpy(ifr.ifr_name, handle->md.mondevice, sizeof(ifr.ifr_name));
|
|
if (ioctl(sock_fd, SIOCGIFFLAGS, &ifr) == -1) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"%s: Can't get flags for %s: %s", device,
|
|
handle->md.mondevice, strerror(errno));
|
|
del_mon_if(handle, sock_fd, &nlstate, device,
|
|
handle->md.mondevice);
|
|
nl80211_cleanup(&nlstate);
|
|
return PCAP_ERROR;
|
|
}
|
|
ifr.ifr_flags |= IFF_UP|IFF_RUNNING;
|
|
if (ioctl(sock_fd, SIOCSIFFLAGS, &ifr) == -1) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"%s: Can't set flags for %s: %s", device,
|
|
handle->md.mondevice, strerror(errno));
|
|
del_mon_if(handle, sock_fd, &nlstate, device,
|
|
handle->md.mondevice);
|
|
nl80211_cleanup(&nlstate);
|
|
return PCAP_ERROR;
|
|
}
|
|
|
|
/*
|
|
* Success. Clean up the libnl state.
|
|
*/
|
|
nl80211_cleanup(&nlstate);
|
|
|
|
/*
|
|
* Note that we have to delete the monitor device when we close
|
|
* the handle.
|
|
*/
|
|
handle->md.must_do_on_close |= MUST_DELETE_MONIF;
|
|
|
|
/*
|
|
* Add this to the list of pcaps to close when we exit.
|
|
*/
|
|
pcap_add_to_pcaps_to_close(handle);
|
|
|
|
return 1;
|
|
}
|
|
#endif /* HAVE_LIBNL */
|
|
|
|
static int
|
|
pcap_can_set_rfmon_linux(pcap_t *handle)
|
|
{
|
|
#ifdef HAVE_LIBNL
|
|
char phydev_path[PATH_MAX+1];
|
|
int ret;
|
|
#endif
|
|
#ifdef IW_MODE_MONITOR
|
|
int sock_fd;
|
|
struct iwreq ireq;
|
|
#endif
|
|
|
|
if (strcmp(handle->opt.source, "any") == 0) {
|
|
/*
|
|
* Monitor mode makes no sense on the "any" device.
|
|
*/
|
|
return 0;
|
|
}
|
|
|
|
#ifdef HAVE_LIBNL
|
|
/*
|
|
* Bleah. There doesn't seem to be a way to ask a mac80211
|
|
* device, through libnl, whether it supports monitor mode;
|
|
* we'll just check whether the device appears to be a
|
|
* mac80211 device and, if so, assume the device supports
|
|
* monitor mode.
|
|
*
|
|
* wmaster devices don't appear to support the Wireless
|
|
* Extensions, but we can create a mon device for a
|
|
* wmaster device, so we don't bother checking whether
|
|
* a mac80211 device supports the Wireless Extensions.
|
|
*/
|
|
ret = get_mac80211_phydev(handle, handle->opt.source, phydev_path,
|
|
PATH_MAX);
|
|
if (ret < 0)
|
|
return ret; /* error */
|
|
if (ret == 1)
|
|
return 1; /* mac80211 device */
|
|
#endif
|
|
|
|
#ifdef IW_MODE_MONITOR
|
|
/*
|
|
* Bleah. There doesn't appear to be an ioctl to use to ask
|
|
* whether a device supports monitor mode; we'll just do
|
|
* SIOCGIWMODE and, if it succeeds, assume the device supports
|
|
* monitor mode.
|
|
*
|
|
* Open a socket on which to attempt to get the mode.
|
|
* (We assume that if we have Wireless Extensions support
|
|
* we also have PF_PACKET support.)
|
|
*/
|
|
sock_fd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
|
|
if (sock_fd == -1) {
|
|
(void)snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"socket: %s", pcap_strerror(errno));
|
|
return PCAP_ERROR;
|
|
}
|
|
|
|
/*
|
|
* Attempt to get the current mode.
|
|
*/
|
|
strncpy(ireq.ifr_ifrn.ifrn_name, handle->opt.source,
|
|
sizeof ireq.ifr_ifrn.ifrn_name);
|
|
ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
|
|
if (ioctl(sock_fd, SIOCGIWMODE, &ireq) != -1) {
|
|
/*
|
|
* Well, we got the mode; assume we can set it.
|
|
*/
|
|
close(sock_fd);
|
|
return 1;
|
|
}
|
|
if (errno == ENODEV) {
|
|
/* The device doesn't even exist. */
|
|
(void)snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"SIOCGIWMODE failed: %s", pcap_strerror(errno));
|
|
close(sock_fd);
|
|
return PCAP_ERROR_NO_SUCH_DEVICE;
|
|
}
|
|
close(sock_fd);
|
|
#endif
|
|
return 0;
|
|
}
|
|
|
|
/* grabs the number of dropped packets by the interface from /proc/net/dev */
|
|
static long int
|
|
linux_if_drops(const char * if_name)
|
|
{
|
|
char buffer[512];
|
|
char * bufptr;
|
|
FILE * file;
|
|
int field_to_convert = 3, if_name_sz = strlen(if_name);
|
|
long int dropped_pkts = 0;
|
|
|
|
file = fopen("/proc/net/dev", "r");
|
|
if (!file)
|
|
return 0;
|
|
|
|
while (!dropped_pkts && fgets( buffer, sizeof(buffer), file ))
|
|
{
|
|
/* search for 'bytes' -- if its in there, then
|
|
that means we need to grab the fourth field. otherwise
|
|
grab the third field. */
|
|
if (field_to_convert != 4 && strstr(buffer, "bytes"))
|
|
{
|
|
field_to_convert = 4;
|
|
continue;
|
|
}
|
|
|
|
/* find iface and make sure it actually matches -- space before the name and : after it */
|
|
if ((bufptr = strstr(buffer, if_name)) &&
|
|
(bufptr == buffer || *(bufptr-1) == ' ') &&
|
|
*(bufptr + if_name_sz) == ':')
|
|
{
|
|
bufptr = bufptr + if_name_sz + 1;
|
|
|
|
/* grab the nth field from it */
|
|
while( --field_to_convert && *bufptr != '\0')
|
|
{
|
|
while (*bufptr != '\0' && *(bufptr++) == ' ');
|
|
while (*bufptr != '\0' && *(bufptr++) != ' ');
|
|
}
|
|
|
|
/* get rid of any final spaces */
|
|
while (*bufptr != '\0' && *bufptr == ' ') bufptr++;
|
|
|
|
if (*bufptr != '\0')
|
|
dropped_pkts = strtol(bufptr, NULL, 10);
|
|
|
|
break;
|
|
}
|
|
}
|
|
|
|
fclose(file);
|
|
return dropped_pkts;
|
|
}
|
|
|
|
|
|
/*
|
|
* With older kernels promiscuous mode is kind of interesting because we
|
|
* have to reset the interface before exiting. The problem can't really
|
|
* be solved without some daemon taking care of managing usage counts.
|
|
* If we put the interface into promiscuous mode, we set a flag indicating
|
|
* that we must take it out of that mode when the interface is closed,
|
|
* and, when closing the interface, if that flag is set we take it out
|
|
* of promiscuous mode.
|
|
*
|
|
* Even with newer kernels, we have the same issue with rfmon mode.
|
|
*/
|
|
|
|
static void pcap_cleanup_linux( pcap_t *handle )
|
|
{
|
|
struct ifreq ifr;
|
|
#ifdef HAVE_LIBNL
|
|
struct nl80211_state nlstate;
|
|
int ret;
|
|
#endif /* HAVE_LIBNL */
|
|
#ifdef IW_MODE_MONITOR
|
|
struct iwreq ireq;
|
|
#endif /* IW_MODE_MONITOR */
|
|
|
|
if (handle->md.must_do_on_close != 0) {
|
|
/*
|
|
* There's something we have to do when closing this
|
|
* pcap_t.
|
|
*/
|
|
if (handle->md.must_do_on_close & MUST_CLEAR_PROMISC) {
|
|
/*
|
|
* We put the interface into promiscuous mode;
|
|
* take it out of promiscuous mode.
|
|
*
|
|
* XXX - if somebody else wants it in promiscuous
|
|
* mode, this code cannot know that, so it'll take
|
|
* it out of promiscuous mode. That's not fixable
|
|
* in 2.0[.x] kernels.
|
|
*/
|
|
memset(&ifr, 0, sizeof(ifr));
|
|
strncpy(ifr.ifr_name, handle->md.device,
|
|
sizeof(ifr.ifr_name));
|
|
if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) == -1) {
|
|
fprintf(stderr,
|
|
"Can't restore interface flags (SIOCGIFFLAGS failed: %s).\n"
|
|
"Please adjust manually.\n"
|
|
"Hint: This can't happen with Linux >= 2.2.0.\n",
|
|
strerror(errno));
|
|
} else {
|
|
if (ifr.ifr_flags & IFF_PROMISC) {
|
|
/*
|
|
* Promiscuous mode is currently on;
|
|
* turn it off.
|
|
*/
|
|
ifr.ifr_flags &= ~IFF_PROMISC;
|
|
if (ioctl(handle->fd, SIOCSIFFLAGS,
|
|
&ifr) == -1) {
|
|
fprintf(stderr,
|
|
"Can't restore interface flags (SIOCSIFFLAGS failed: %s).\n"
|
|
"Please adjust manually.\n"
|
|
"Hint: This can't happen with Linux >= 2.2.0.\n",
|
|
strerror(errno));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
#ifdef HAVE_LIBNL
|
|
if (handle->md.must_do_on_close & MUST_DELETE_MONIF) {
|
|
ret = nl80211_init(handle, &nlstate, handle->md.device);
|
|
if (ret >= 0) {
|
|
ret = del_mon_if(handle, handle->fd, &nlstate,
|
|
handle->md.device, handle->md.mondevice);
|
|
nl80211_cleanup(&nlstate);
|
|
}
|
|
if (ret < 0) {
|
|
fprintf(stderr,
|
|
"Can't delete monitor interface %s (%s).\n"
|
|
"Please delete manually.\n",
|
|
handle->md.mondevice, handle->errbuf);
|
|
}
|
|
}
|
|
#endif /* HAVE_LIBNL */
|
|
|
|
#ifdef IW_MODE_MONITOR
|
|
if (handle->md.must_do_on_close & MUST_CLEAR_RFMON) {
|
|
/*
|
|
* We put the interface into rfmon mode;
|
|
* take it out of rfmon mode.
|
|
*
|
|
* XXX - if somebody else wants it in rfmon
|
|
* mode, this code cannot know that, so it'll take
|
|
* it out of rfmon mode.
|
|
*/
|
|
strncpy(ireq.ifr_ifrn.ifrn_name, handle->md.device,
|
|
sizeof ireq.ifr_ifrn.ifrn_name);
|
|
ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1]
|
|
= 0;
|
|
ireq.u.mode = handle->md.oldmode;
|
|
if (ioctl(handle->fd, SIOCSIWMODE, &ireq) == -1) {
|
|
/*
|
|
* Scientist, you've failed.
|
|
*/
|
|
fprintf(stderr,
|
|
"Can't restore interface wireless mode (SIOCSIWMODE failed: %s).\n"
|
|
"Please adjust manually.\n",
|
|
strerror(errno));
|
|
}
|
|
}
|
|
#endif /* IW_MODE_MONITOR */
|
|
|
|
/*
|
|
* Take this pcap out of the list of pcaps for which we
|
|
* have to take the interface out of some mode.
|
|
*/
|
|
pcap_remove_from_pcaps_to_close(handle);
|
|
}
|
|
|
|
if (handle->md.mondevice != NULL) {
|
|
free(handle->md.mondevice);
|
|
handle->md.mondevice = NULL;
|
|
}
|
|
if (handle->md.device != NULL) {
|
|
free(handle->md.device);
|
|
handle->md.device = NULL;
|
|
}
|
|
pcap_cleanup_live_common(handle);
|
|
}
|
|
|
|
/*
|
|
* Get a handle for a live capture from the given device. You can
|
|
* pass NULL as device to get all packages (without link level
|
|
* information of course). If you pass 1 as promisc the interface
|
|
* will be set to promiscous mode (XXX: I think this usage should
|
|
* be deprecated and functions be added to select that later allow
|
|
* modification of that values -- Torsten).
|
|
*/
|
|
static int
|
|
pcap_activate_linux(pcap_t *handle)
|
|
{
|
|
const char *device;
|
|
int status = 0;
|
|
|
|
device = handle->opt.source;
|
|
|
|
handle->inject_op = pcap_inject_linux;
|
|
handle->setfilter_op = pcap_setfilter_linux;
|
|
handle->setdirection_op = pcap_setdirection_linux;
|
|
handle->set_datalink_op = NULL; /* can't change data link type */
|
|
handle->getnonblock_op = pcap_getnonblock_fd;
|
|
handle->setnonblock_op = pcap_setnonblock_fd;
|
|
handle->cleanup_op = pcap_cleanup_linux;
|
|
handle->read_op = pcap_read_linux;
|
|
handle->stats_op = pcap_stats_linux;
|
|
|
|
/*
|
|
* The "any" device is a special device which causes us not
|
|
* to bind to a particular device and thus to look at all
|
|
* devices.
|
|
*/
|
|
if (strcmp(device, "any") == 0) {
|
|
if (handle->opt.promisc) {
|
|
handle->opt.promisc = 0;
|
|
/* Just a warning. */
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"Promiscuous mode not supported on the \"any\" device");
|
|
status = PCAP_WARNING_PROMISC_NOTSUP;
|
|
}
|
|
}
|
|
|
|
handle->md.device = strdup(device);
|
|
if (handle->md.device == NULL) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "strdup: %s",
|
|
pcap_strerror(errno) );
|
|
return PCAP_ERROR;
|
|
}
|
|
|
|
/*
|
|
* If we're in promiscuous mode, then we probably want
|
|
* to see when the interface drops packets too, so get an
|
|
* initial count from /proc/net/dev
|
|
*/
|
|
if (handle->opt.promisc)
|
|
handle->md.proc_dropped = linux_if_drops(handle->md.device);
|
|
|
|
/*
|
|
* Current Linux kernels use the protocol family PF_PACKET to
|
|
* allow direct access to all packets on the network while
|
|
* older kernels had a special socket type SOCK_PACKET to
|
|
* implement this feature.
|
|
* While this old implementation is kind of obsolete we need
|
|
* to be compatible with older kernels for a while so we are
|
|
* trying both methods with the newer method preferred.
|
|
*/
|
|
|
|
if ((status = activate_new(handle)) == 1) {
|
|
/*
|
|
* Success.
|
|
* Try to use memory-mapped access.
|
|
*/
|
|
switch (activate_mmap(handle)) {
|
|
|
|
case 1:
|
|
/* we succeeded; nothing more to do */
|
|
return 0;
|
|
|
|
case 0:
|
|
/*
|
|
* Kernel doesn't support it - just continue
|
|
* with non-memory-mapped access.
|
|
*/
|
|
status = 0;
|
|
break;
|
|
|
|
case -1:
|
|
/*
|
|
* We failed to set up to use it, or kernel
|
|
* supports it, but we failed to enable it;
|
|
* return an error. handle->errbuf contains
|
|
* an error message.
|
|
*/
|
|
status = PCAP_ERROR;
|
|
goto fail;
|
|
}
|
|
}
|
|
else if (status == 0) {
|
|
/* Non-fatal error; try old way */
|
|
if ((status = activate_old(handle)) != 1) {
|
|
/*
|
|
* Both methods to open the packet socket failed.
|
|
* Tidy up and report our failure (handle->errbuf
|
|
* is expected to be set by the functions above).
|
|
*/
|
|
goto fail;
|
|
}
|
|
} else {
|
|
/*
|
|
* Fatal error with the new way; just fail.
|
|
* status has the error return; if it's PCAP_ERROR,
|
|
* handle->errbuf has been set appropriately.
|
|
*/
|
|
goto fail;
|
|
}
|
|
|
|
/*
|
|
* We set up the socket, but not with memory-mapped access.
|
|
*/
|
|
if (handle->opt.buffer_size != 0) {
|
|
/*
|
|
* Set the socket buffer size to the specified value.
|
|
*/
|
|
if (setsockopt(handle->fd, SOL_SOCKET, SO_RCVBUF,
|
|
&handle->opt.buffer_size,
|
|
sizeof(handle->opt.buffer_size)) == -1) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"SO_RCVBUF: %s", pcap_strerror(errno));
|
|
status = PCAP_ERROR;
|
|
goto fail;
|
|
}
|
|
}
|
|
|
|
/* Allocate the buffer */
|
|
|
|
handle->buffer = malloc(handle->bufsize + handle->offset);
|
|
if (!handle->buffer) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"malloc: %s", pcap_strerror(errno));
|
|
status = PCAP_ERROR;
|
|
goto fail;
|
|
}
|
|
|
|
/*
|
|
* "handle->fd" is a socket, so "select()" and "poll()"
|
|
* should work on it.
|
|
*/
|
|
handle->selectable_fd = handle->fd;
|
|
|
|
return status;
|
|
|
|
fail:
|
|
pcap_cleanup_linux(handle);
|
|
return status;
|
|
}
|
|
|
|
/*
|
|
* Read at most max_packets from the capture stream and call the callback
|
|
* for each of them. Returns the number of packets handled or -1 if an
|
|
* error occured.
|
|
*/
|
|
static int
|
|
pcap_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user)
|
|
{
|
|
/*
|
|
* Currently, on Linux only one packet is delivered per read,
|
|
* so we don't loop.
|
|
*/
|
|
return pcap_read_packet(handle, callback, user);
|
|
}
|
|
|
|
/*
|
|
* Read a packet from the socket calling the handler provided by
|
|
* the user. Returns the number of packets received or -1 if an
|
|
* error occured.
|
|
*/
|
|
static int
|
|
pcap_read_packet(pcap_t *handle, pcap_handler callback, u_char *userdata)
|
|
{
|
|
u_char *bp;
|
|
int offset;
|
|
#ifdef HAVE_PF_PACKET_SOCKETS
|
|
struct sockaddr_ll from;
|
|
struct sll_header *hdrp;
|
|
#else
|
|
struct sockaddr from;
|
|
#endif
|
|
#if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI)
|
|
struct iovec iov;
|
|
struct msghdr msg;
|
|
struct cmsghdr *cmsg;
|
|
union {
|
|
struct cmsghdr cmsg;
|
|
char buf[CMSG_SPACE(sizeof(struct tpacket_auxdata))];
|
|
} cmsg_buf;
|
|
#else /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */
|
|
socklen_t fromlen;
|
|
#endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */
|
|
int packet_len, caplen;
|
|
struct pcap_pkthdr pcap_header;
|
|
|
|
#ifdef HAVE_PF_PACKET_SOCKETS
|
|
/*
|
|
* If this is a cooked device, leave extra room for a
|
|
* fake packet header.
|
|
*/
|
|
if (handle->md.cooked)
|
|
offset = SLL_HDR_LEN;
|
|
else
|
|
offset = 0;
|
|
#else
|
|
/*
|
|
* This system doesn't have PF_PACKET sockets, so it doesn't
|
|
* support cooked devices.
|
|
*/
|
|
offset = 0;
|
|
#endif
|
|
|
|
/*
|
|
* Receive a single packet from the kernel.
|
|
* We ignore EINTR, as that might just be due to a signal
|
|
* being delivered - if the signal should interrupt the
|
|
* loop, the signal handler should call pcap_breakloop()
|
|
* to set handle->break_loop (we ignore it on other
|
|
* platforms as well).
|
|
* We also ignore ENETDOWN, so that we can continue to
|
|
* capture traffic if the interface goes down and comes
|
|
* back up again; comments in the kernel indicate that
|
|
* we'll just block waiting for packets if we try to
|
|
* receive from a socket that delivered ENETDOWN, and,
|
|
* if we're using a memory-mapped buffer, we won't even
|
|
* get notified of "network down" events.
|
|
*/
|
|
bp = handle->buffer + handle->offset;
|
|
|
|
#if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI)
|
|
msg.msg_name = &from;
|
|
msg.msg_namelen = sizeof(from);
|
|
msg.msg_iov = &iov;
|
|
msg.msg_iovlen = 1;
|
|
msg.msg_control = &cmsg_buf;
|
|
msg.msg_controllen = sizeof(cmsg_buf);
|
|
msg.msg_flags = 0;
|
|
|
|
iov.iov_len = handle->bufsize - offset;
|
|
iov.iov_base = bp + offset;
|
|
#endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */
|
|
|
|
do {
|
|
/*
|
|
* Has "pcap_breakloop()" been called?
|
|
*/
|
|
if (handle->break_loop) {
|
|
/*
|
|
* Yes - clear the flag that indicates that it
|
|
* has, and return -2 as an indication that we
|
|
* were told to break out of the loop.
|
|
*/
|
|
handle->break_loop = 0;
|
|
return -2;
|
|
}
|
|
|
|
#if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI)
|
|
packet_len = recvmsg(handle->fd, &msg, MSG_TRUNC);
|
|
#else /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */
|
|
fromlen = sizeof(from);
|
|
packet_len = recvfrom(
|
|
handle->fd, bp + offset,
|
|
handle->bufsize - offset, MSG_TRUNC,
|
|
(struct sockaddr *) &from, &fromlen);
|
|
#endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */
|
|
} while (packet_len == -1 && (errno == EINTR || errno == ENETDOWN));
|
|
|
|
/* Check if an error occured */
|
|
|
|
if (packet_len == -1) {
|
|
if (errno == EAGAIN)
|
|
return 0; /* no packet there */
|
|
else {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"recvfrom: %s", pcap_strerror(errno));
|
|
return -1;
|
|
}
|
|
}
|
|
|
|
#ifdef HAVE_PF_PACKET_SOCKETS
|
|
if (!handle->md.sock_packet) {
|
|
/*
|
|
* Unfortunately, there is a window between socket() and
|
|
* bind() where the kernel may queue packets from any
|
|
* interface. If we're bound to a particular interface,
|
|
* discard packets not from that interface.
|
|
*
|
|
* (If socket filters are supported, we could do the
|
|
* same thing we do when changing the filter; however,
|
|
* that won't handle packet sockets without socket
|
|
* filter support, and it's a bit more complicated.
|
|
* It would save some instructions per packet, however.)
|
|
*/
|
|
if (handle->md.ifindex != -1 &&
|
|
from.sll_ifindex != handle->md.ifindex)
|
|
return 0;
|
|
|
|
/*
|
|
* Do checks based on packet direction.
|
|
* We can only do this if we're using PF_PACKET; the
|
|
* address returned for SOCK_PACKET is a "sockaddr_pkt"
|
|
* which lacks the relevant packet type information.
|
|
*/
|
|
if (from.sll_pkttype == PACKET_OUTGOING) {
|
|
/*
|
|
* Outgoing packet.
|
|
* If this is from the loopback device, reject it;
|
|
* we'll see the packet as an incoming packet as well,
|
|
* and we don't want to see it twice.
|
|
*/
|
|
if (from.sll_ifindex == handle->md.lo_ifindex)
|
|
return 0;
|
|
|
|
/*
|
|
* If the user only wants incoming packets, reject it.
|
|
*/
|
|
if (handle->direction == PCAP_D_IN)
|
|
return 0;
|
|
} else {
|
|
/*
|
|
* Incoming packet.
|
|
* If the user only wants outgoing packets, reject it.
|
|
*/
|
|
if (handle->direction == PCAP_D_OUT)
|
|
return 0;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
#ifdef HAVE_PF_PACKET_SOCKETS
|
|
/*
|
|
* If this is a cooked device, fill in the fake packet header.
|
|
*/
|
|
if (handle->md.cooked) {
|
|
/*
|
|
* Add the length of the fake header to the length
|
|
* of packet data we read.
|
|
*/
|
|
packet_len += SLL_HDR_LEN;
|
|
|
|
hdrp = (struct sll_header *)bp;
|
|
hdrp->sll_pkttype = map_packet_type_to_sll_type(from.sll_pkttype);
|
|
hdrp->sll_hatype = htons(from.sll_hatype);
|
|
hdrp->sll_halen = htons(from.sll_halen);
|
|
memcpy(hdrp->sll_addr, from.sll_addr,
|
|
(from.sll_halen > SLL_ADDRLEN) ?
|
|
SLL_ADDRLEN :
|
|
from.sll_halen);
|
|
hdrp->sll_protocol = from.sll_protocol;
|
|
}
|
|
|
|
#if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI)
|
|
for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
|
|
struct tpacket_auxdata *aux;
|
|
unsigned int len;
|
|
struct vlan_tag *tag;
|
|
|
|
if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct tpacket_auxdata)) ||
|
|
cmsg->cmsg_level != SOL_PACKET ||
|
|
cmsg->cmsg_type != PACKET_AUXDATA)
|
|
continue;
|
|
|
|
aux = (struct tpacket_auxdata *)CMSG_DATA(cmsg);
|
|
if (aux->tp_vlan_tci == 0)
|
|
continue;
|
|
|
|
len = packet_len > iov.iov_len ? iov.iov_len : packet_len;
|
|
if (len < 2 * ETH_ALEN)
|
|
break;
|
|
|
|
bp -= VLAN_TAG_LEN;
|
|
memmove(bp, bp + VLAN_TAG_LEN, 2 * ETH_ALEN);
|
|
|
|
tag = (struct vlan_tag *)(bp + 2 * ETH_ALEN);
|
|
tag->vlan_tpid = htons(ETH_P_8021Q);
|
|
tag->vlan_tci = htons(aux->tp_vlan_tci);
|
|
|
|
packet_len += VLAN_TAG_LEN;
|
|
}
|
|
#endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */
|
|
#endif /* HAVE_PF_PACKET_SOCKETS */
|
|
|
|
/*
|
|
* XXX: According to the kernel source we should get the real
|
|
* packet len if calling recvfrom with MSG_TRUNC set. It does
|
|
* not seem to work here :(, but it is supported by this code
|
|
* anyway.
|
|
* To be honest the code RELIES on that feature so this is really
|
|
* broken with 2.2.x kernels.
|
|
* I spend a day to figure out what's going on and I found out
|
|
* that the following is happening:
|
|
*
|
|
* The packet comes from a random interface and the packet_rcv
|
|
* hook is called with a clone of the packet. That code inserts
|
|
* the packet into the receive queue of the packet socket.
|
|
* If a filter is attached to that socket that filter is run
|
|
* first - and there lies the problem. The default filter always
|
|
* cuts the packet at the snaplen:
|
|
*
|
|
* # tcpdump -d
|
|
* (000) ret #68
|
|
*
|
|
* So the packet filter cuts down the packet. The recvfrom call
|
|
* says "hey, it's only 68 bytes, it fits into the buffer" with
|
|
* the result that we don't get the real packet length. This
|
|
* is valid at least until kernel 2.2.17pre6.
|
|
*
|
|
* We currently handle this by making a copy of the filter
|
|
* program, fixing all "ret" instructions with non-zero
|
|
* operands to have an operand of 65535 so that the filter
|
|
* doesn't truncate the packet, and supplying that modified
|
|
* filter to the kernel.
|
|
*/
|
|
|
|
caplen = packet_len;
|
|
if (caplen > handle->snapshot)
|
|
caplen = handle->snapshot;
|
|
|
|
/* Run the packet filter if not using kernel filter */
|
|
if (!handle->md.use_bpf && handle->fcode.bf_insns) {
|
|
if (bpf_filter(handle->fcode.bf_insns, bp,
|
|
packet_len, caplen) == 0)
|
|
{
|
|
/* rejected by filter */
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
/* Fill in our own header data */
|
|
|
|
if (ioctl(handle->fd, SIOCGSTAMP, &pcap_header.ts) == -1) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"SIOCGSTAMP: %s", pcap_strerror(errno));
|
|
return -1;
|
|
}
|
|
pcap_header.caplen = caplen;
|
|
pcap_header.len = packet_len;
|
|
|
|
/*
|
|
* Count the packet.
|
|
*
|
|
* Arguably, we should count them before we check the filter,
|
|
* as on many other platforms "ps_recv" counts packets
|
|
* handed to the filter rather than packets that passed
|
|
* the filter, but if filtering is done in the kernel, we
|
|
* can't get a count of packets that passed the filter,
|
|
* and that would mean the meaning of "ps_recv" wouldn't
|
|
* be the same on all Linux systems.
|
|
*
|
|
* XXX - it's not the same on all systems in any case;
|
|
* ideally, we should have a "get the statistics" call
|
|
* that supplies more counts and indicates which of them
|
|
* it supplies, so that we supply a count of packets
|
|
* handed to the filter only on platforms where that
|
|
* information is available.
|
|
*
|
|
* We count them here even if we can get the packet count
|
|
* from the kernel, as we can only determine at run time
|
|
* whether we'll be able to get it from the kernel (if
|
|
* HAVE_TPACKET_STATS isn't defined, we can't get it from
|
|
* the kernel, but if it is defined, the library might
|
|
* have been built with a 2.4 or later kernel, but we
|
|
* might be running on a 2.2[.x] kernel without Alexey
|
|
* Kuznetzov's turbopacket patches, and thus the kernel
|
|
* might not be able to supply those statistics). We
|
|
* could, I guess, try, when opening the socket, to get
|
|
* the statistics, and if we can not increment the count
|
|
* here, but it's not clear that always incrementing
|
|
* the count is more expensive than always testing a flag
|
|
* in memory.
|
|
*
|
|
* We keep the count in "md.packets_read", and use that for
|
|
* "ps_recv" if we can't get the statistics from the kernel.
|
|
* We do that because, if we *can* get the statistics from
|
|
* the kernel, we use "md.stat.ps_recv" and "md.stat.ps_drop"
|
|
* as running counts, as reading the statistics from the
|
|
* kernel resets the kernel statistics, and if we directly
|
|
* increment "md.stat.ps_recv" here, that means it will
|
|
* count packets *twice* on systems where we can get kernel
|
|
* statistics - once here, and once in pcap_stats_linux().
|
|
*/
|
|
handle->md.packets_read++;
|
|
|
|
/* Call the user supplied callback function */
|
|
callback(userdata, &pcap_header, bp);
|
|
|
|
return 1;
|
|
}
|
|
|
|
static int
|
|
pcap_inject_linux(pcap_t *handle, const void *buf, size_t size)
|
|
{
|
|
int ret;
|
|
|
|
#ifdef HAVE_PF_PACKET_SOCKETS
|
|
if (!handle->md.sock_packet) {
|
|
/* PF_PACKET socket */
|
|
if (handle->md.ifindex == -1) {
|
|
/*
|
|
* We don't support sending on the "any" device.
|
|
*/
|
|
strlcpy(handle->errbuf,
|
|
"Sending packets isn't supported on the \"any\" device",
|
|
PCAP_ERRBUF_SIZE);
|
|
return (-1);
|
|
}
|
|
|
|
if (handle->md.cooked) {
|
|
/*
|
|
* We don't support sending on the "any" device.
|
|
*
|
|
* XXX - how do you send on a bound cooked-mode
|
|
* socket?
|
|
* Is a "sendto()" required there?
|
|
*/
|
|
strlcpy(handle->errbuf,
|
|
"Sending packets isn't supported in cooked mode",
|
|
PCAP_ERRBUF_SIZE);
|
|
return (-1);
|
|
}
|
|
}
|
|
#endif
|
|
|
|
ret = send(handle->fd, buf, size, 0);
|
|
if (ret == -1) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "send: %s",
|
|
pcap_strerror(errno));
|
|
return (-1);
|
|
}
|
|
return (ret);
|
|
}
|
|
|
|
/*
|
|
* Get the statistics for the given packet capture handle.
|
|
* Reports the number of dropped packets iff the kernel supports
|
|
* the PACKET_STATISTICS "getsockopt()" argument (2.4 and later
|
|
* kernels, and 2.2[.x] kernels with Alexey Kuznetzov's turbopacket
|
|
* patches); otherwise, that information isn't available, and we lie
|
|
* and report 0 as the count of dropped packets.
|
|
*/
|
|
static int
|
|
pcap_stats_linux(pcap_t *handle, struct pcap_stat *stats)
|
|
{
|
|
#ifdef HAVE_TPACKET_STATS
|
|
struct tpacket_stats kstats;
|
|
socklen_t len = sizeof (struct tpacket_stats);
|
|
#endif
|
|
|
|
long if_dropped = 0;
|
|
|
|
/*
|
|
* To fill in ps_ifdrop, we parse /proc/net/dev for the number
|
|
*/
|
|
if (handle->opt.promisc)
|
|
{
|
|
if_dropped = handle->md.proc_dropped;
|
|
handle->md.proc_dropped = linux_if_drops(handle->md.device);
|
|
handle->md.stat.ps_ifdrop += (handle->md.proc_dropped - if_dropped);
|
|
}
|
|
|
|
#ifdef HAVE_TPACKET_STATS
|
|
/*
|
|
* Try to get the packet counts from the kernel.
|
|
*/
|
|
if (getsockopt(handle->fd, SOL_PACKET, PACKET_STATISTICS,
|
|
&kstats, &len) > -1) {
|
|
/*
|
|
* On systems where the PACKET_STATISTICS "getsockopt()"
|
|
* argument is supported on PF_PACKET sockets:
|
|
*
|
|
* "ps_recv" counts only packets that *passed* the
|
|
* filter, not packets that didn't pass the filter.
|
|
* This includes packets later dropped because we
|
|
* ran out of buffer space.
|
|
*
|
|
* "ps_drop" counts packets dropped because we ran
|
|
* out of buffer space. It doesn't count packets
|
|
* dropped by the interface driver. It counts only
|
|
* packets that passed the filter.
|
|
*
|
|
* See above for ps_ifdrop.
|
|
*
|
|
* Both statistics include packets not yet read from
|
|
* the kernel by libpcap, and thus not yet seen by
|
|
* the application.
|
|
*
|
|
* In "linux/net/packet/af_packet.c", at least in the
|
|
* 2.4.9 kernel, "tp_packets" is incremented for every
|
|
* packet that passes the packet filter *and* is
|
|
* successfully queued on the socket; "tp_drops" is
|
|
* incremented for every packet dropped because there's
|
|
* not enough free space in the socket buffer.
|
|
*
|
|
* When the statistics are returned for a PACKET_STATISTICS
|
|
* "getsockopt()" call, "tp_drops" is added to "tp_packets",
|
|
* so that "tp_packets" counts all packets handed to
|
|
* the PF_PACKET socket, including packets dropped because
|
|
* there wasn't room on the socket buffer - but not
|
|
* including packets that didn't pass the filter.
|
|
*
|
|
* In the BSD BPF, the count of received packets is
|
|
* incremented for every packet handed to BPF, regardless
|
|
* of whether it passed the filter.
|
|
*
|
|
* We can't make "pcap_stats()" work the same on both
|
|
* platforms, but the best approximation is to return
|
|
* "tp_packets" as the count of packets and "tp_drops"
|
|
* as the count of drops.
|
|
*
|
|
* Keep a running total because each call to
|
|
* getsockopt(handle->fd, SOL_PACKET, PACKET_STATISTICS, ....
|
|
* resets the counters to zero.
|
|
*/
|
|
handle->md.stat.ps_recv += kstats.tp_packets;
|
|
handle->md.stat.ps_drop += kstats.tp_drops;
|
|
*stats = handle->md.stat;
|
|
return 0;
|
|
}
|
|
else
|
|
{
|
|
/*
|
|
* If the error was EOPNOTSUPP, fall through, so that
|
|
* if you build the library on a system with
|
|
* "struct tpacket_stats" and run it on a system
|
|
* that doesn't, it works as it does if the library
|
|
* is built on a system without "struct tpacket_stats".
|
|
*/
|
|
if (errno != EOPNOTSUPP) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"pcap_stats: %s", pcap_strerror(errno));
|
|
return -1;
|
|
}
|
|
}
|
|
#endif
|
|
/*
|
|
* On systems where the PACKET_STATISTICS "getsockopt()" argument
|
|
* is not supported on PF_PACKET sockets:
|
|
*
|
|
* "ps_recv" counts only packets that *passed* the filter,
|
|
* not packets that didn't pass the filter. It does not
|
|
* count packets dropped because we ran out of buffer
|
|
* space.
|
|
*
|
|
* "ps_drop" is not supported.
|
|
*
|
|
* "ps_ifdrop" is supported. It will return the number
|
|
* of drops the interface reports in /proc/net/dev
|
|
*
|
|
* "ps_recv" doesn't include packets not yet read from
|
|
* the kernel by libpcap.
|
|
*
|
|
* We maintain the count of packets processed by libpcap in
|
|
* "md.packets_read", for reasons described in the comment
|
|
* at the end of pcap_read_packet(). We have no idea how many
|
|
* packets were dropped by the kernel buffers -- but we know
|
|
* how many the interface dropped, so we can return that.
|
|
*/
|
|
|
|
stats->ps_recv = handle->md.packets_read;
|
|
stats->ps_drop = 0;
|
|
stats->ps_ifdrop = handle->md.stat.ps_drop;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Description string for the "any" device.
|
|
*/
|
|
static const char any_descr[] = "Pseudo-device that captures on all interfaces";
|
|
|
|
int
|
|
pcap_platform_finddevs(pcap_if_t **alldevsp, char *errbuf)
|
|
{
|
|
if (pcap_add_if(alldevsp, "any", 0, any_descr, errbuf) < 0)
|
|
return (-1);
|
|
|
|
#ifdef HAVE_DAG_API
|
|
if (dag_platform_finddevs(alldevsp, errbuf) < 0)
|
|
return (-1);
|
|
#endif /* HAVE_DAG_API */
|
|
|
|
#ifdef HAVE_SEPTEL_API
|
|
if (septel_platform_finddevs(alldevsp, errbuf) < 0)
|
|
return (-1);
|
|
#endif /* HAVE_SEPTEL_API */
|
|
|
|
#ifdef PCAP_SUPPORT_BT
|
|
if (bt_platform_finddevs(alldevsp, errbuf) < 0)
|
|
return (-1);
|
|
#endif
|
|
|
|
#ifdef PCAP_SUPPORT_USB
|
|
if (usb_platform_finddevs(alldevsp, errbuf) < 0)
|
|
return (-1);
|
|
#endif
|
|
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* Attach the given BPF code to the packet capture device.
|
|
*/
|
|
static int
|
|
pcap_setfilter_linux_common(pcap_t *handle, struct bpf_program *filter,
|
|
int is_mmapped)
|
|
{
|
|
#ifdef SO_ATTACH_FILTER
|
|
struct sock_fprog fcode;
|
|
int can_filter_in_kernel;
|
|
int err = 0;
|
|
#endif
|
|
|
|
if (!handle)
|
|
return -1;
|
|
if (!filter) {
|
|
strncpy(handle->errbuf, "setfilter: No filter specified",
|
|
PCAP_ERRBUF_SIZE);
|
|
return -1;
|
|
}
|
|
|
|
/* Make our private copy of the filter */
|
|
|
|
if (install_bpf_program(handle, filter) < 0)
|
|
/* install_bpf_program() filled in errbuf */
|
|
return -1;
|
|
|
|
/*
|
|
* Run user level packet filter by default. Will be overriden if
|
|
* installing a kernel filter succeeds.
|
|
*/
|
|
handle->md.use_bpf = 0;
|
|
|
|
/* Install kernel level filter if possible */
|
|
|
|
#ifdef SO_ATTACH_FILTER
|
|
#ifdef USHRT_MAX
|
|
if (handle->fcode.bf_len > USHRT_MAX) {
|
|
/*
|
|
* fcode.len is an unsigned short for current kernel.
|
|
* I have yet to see BPF-Code with that much
|
|
* instructions but still it is possible. So for the
|
|
* sake of correctness I added this check.
|
|
*/
|
|
fprintf(stderr, "Warning: Filter too complex for kernel\n");
|
|
fcode.len = 0;
|
|
fcode.filter = NULL;
|
|
can_filter_in_kernel = 0;
|
|
} else
|
|
#endif /* USHRT_MAX */
|
|
{
|
|
/*
|
|
* Oh joy, the Linux kernel uses struct sock_fprog instead
|
|
* of struct bpf_program and of course the length field is
|
|
* of different size. Pointed out by Sebastian
|
|
*
|
|
* Oh, and we also need to fix it up so that all "ret"
|
|
* instructions with non-zero operands have 65535 as the
|
|
* operand if we're not capturing in memory-mapped modee,
|
|
* and so that, if we're in cooked mode, all memory-reference
|
|
* instructions use special magic offsets in references to
|
|
* the link-layer header and assume that the link-layer
|
|
* payload begins at 0; "fix_program()" will do that.
|
|
*/
|
|
switch (fix_program(handle, &fcode, is_mmapped)) {
|
|
|
|
case -1:
|
|
default:
|
|
/*
|
|
* Fatal error; just quit.
|
|
* (The "default" case shouldn't happen; we
|
|
* return -1 for that reason.)
|
|
*/
|
|
return -1;
|
|
|
|
case 0:
|
|
/*
|
|
* The program performed checks that we can't make
|
|
* work in the kernel.
|
|
*/
|
|
can_filter_in_kernel = 0;
|
|
break;
|
|
|
|
case 1:
|
|
/*
|
|
* We have a filter that'll work in the kernel.
|
|
*/
|
|
can_filter_in_kernel = 1;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (can_filter_in_kernel) {
|
|
if ((err = set_kernel_filter(handle, &fcode)) == 0)
|
|
{
|
|
/* Installation succeded - using kernel filter. */
|
|
handle->md.use_bpf = 1;
|
|
}
|
|
else if (err == -1) /* Non-fatal error */
|
|
{
|
|
/*
|
|
* Print a warning if we weren't able to install
|
|
* the filter for a reason other than "this kernel
|
|
* isn't configured to support socket filters.
|
|
*/
|
|
if (errno != ENOPROTOOPT && errno != EOPNOTSUPP) {
|
|
fprintf(stderr,
|
|
"Warning: Kernel filter failed: %s\n",
|
|
pcap_strerror(errno));
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* If we're not using the kernel filter, get rid of any kernel
|
|
* filter that might've been there before, e.g. because the
|
|
* previous filter could work in the kernel, or because some other
|
|
* code attached a filter to the socket by some means other than
|
|
* calling "pcap_setfilter()". Otherwise, the kernel filter may
|
|
* filter out packets that would pass the new userland filter.
|
|
*/
|
|
if (!handle->md.use_bpf)
|
|
reset_kernel_filter(handle);
|
|
|
|
/*
|
|
* Free up the copy of the filter that was made by "fix_program()".
|
|
*/
|
|
if (fcode.filter != NULL)
|
|
free(fcode.filter);
|
|
|
|
if (err == -2)
|
|
/* Fatal error */
|
|
return -1;
|
|
#endif /* SO_ATTACH_FILTER */
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int
|
|
pcap_setfilter_linux(pcap_t *handle, struct bpf_program *filter)
|
|
{
|
|
return pcap_setfilter_linux_common(handle, filter, 0);
|
|
}
|
|
|
|
|
|
/*
|
|
* Set direction flag: Which packets do we accept on a forwarding
|
|
* single device? IN, OUT or both?
|
|
*/
|
|
static int
|
|
pcap_setdirection_linux(pcap_t *handle, pcap_direction_t d)
|
|
{
|
|
#ifdef HAVE_PF_PACKET_SOCKETS
|
|
if (!handle->md.sock_packet) {
|
|
handle->direction = d;
|
|
return 0;
|
|
}
|
|
#endif
|
|
/*
|
|
* We're not using PF_PACKET sockets, so we can't determine
|
|
* the direction of the packet.
|
|
*/
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"Setting direction is not supported on SOCK_PACKET sockets");
|
|
return -1;
|
|
}
|
|
|
|
|
|
#ifdef HAVE_PF_PACKET_SOCKETS
|
|
/*
|
|
* Map the PACKET_ value to a LINUX_SLL_ value; we
|
|
* want the same numerical value to be used in
|
|
* the link-layer header even if the numerical values
|
|
* for the PACKET_ #defines change, so that programs
|
|
* that look at the packet type field will always be
|
|
* able to handle DLT_LINUX_SLL captures.
|
|
*/
|
|
static short int
|
|
map_packet_type_to_sll_type(short int sll_pkttype)
|
|
{
|
|
switch (sll_pkttype) {
|
|
|
|
case PACKET_HOST:
|
|
return htons(LINUX_SLL_HOST);
|
|
|
|
case PACKET_BROADCAST:
|
|
return htons(LINUX_SLL_BROADCAST);
|
|
|
|
case PACKET_MULTICAST:
|
|
return htons(LINUX_SLL_MULTICAST);
|
|
|
|
case PACKET_OTHERHOST:
|
|
return htons(LINUX_SLL_OTHERHOST);
|
|
|
|
case PACKET_OUTGOING:
|
|
return htons(LINUX_SLL_OUTGOING);
|
|
|
|
default:
|
|
return -1;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Linux uses the ARP hardware type to identify the type of an
|
|
* interface. pcap uses the DLT_xxx constants for this. This
|
|
* function takes a pointer to a "pcap_t", and an ARPHRD_xxx
|
|
* constant, as arguments, and sets "handle->linktype" to the
|
|
* appropriate DLT_XXX constant and sets "handle->offset" to
|
|
* the appropriate value (to make "handle->offset" plus link-layer
|
|
* header length be a multiple of 4, so that the link-layer payload
|
|
* will be aligned on a 4-byte boundary when capturing packets).
|
|
* (If the offset isn't set here, it'll be 0; add code as appropriate
|
|
* for cases where it shouldn't be 0.)
|
|
*
|
|
* If "cooked_ok" is non-zero, we can use DLT_LINUX_SLL and capture
|
|
* in cooked mode; otherwise, we can't use cooked mode, so we have
|
|
* to pick some type that works in raw mode, or fail.
|
|
*
|
|
* Sets the link type to -1 if unable to map the type.
|
|
*/
|
|
static void map_arphrd_to_dlt(pcap_t *handle, int arptype, int cooked_ok)
|
|
{
|
|
switch (arptype) {
|
|
|
|
case ARPHRD_ETHER:
|
|
/*
|
|
* This is (presumably) a real Ethernet capture; give it a
|
|
* link-layer-type list with DLT_EN10MB and DLT_DOCSIS, so
|
|
* that an application can let you choose it, in case you're
|
|
* capturing DOCSIS traffic that a Cisco Cable Modem
|
|
* Termination System is putting out onto an Ethernet (it
|
|
* doesn't put an Ethernet header onto the wire, it puts raw
|
|
* DOCSIS frames out on the wire inside the low-level
|
|
* Ethernet framing).
|
|
*
|
|
* XXX - are there any sorts of "fake Ethernet" that have
|
|
* ARPHRD_ETHER but that *shouldn't offer DLT_DOCSIS as
|
|
* a Cisco CMTS won't put traffic onto it or get traffic
|
|
* bridged onto it? ISDN is handled in "activate_new()",
|
|
* as we fall back on cooked mode there; are there any
|
|
* others?
|
|
*/
|
|
handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
|
|
/*
|
|
* If that fails, just leave the list empty.
|
|
*/
|
|
if (handle->dlt_list != NULL) {
|
|
handle->dlt_list[0] = DLT_EN10MB;
|
|
handle->dlt_list[1] = DLT_DOCSIS;
|
|
handle->dlt_count = 2;
|
|
}
|
|
/* FALLTHROUGH */
|
|
|
|
case ARPHRD_METRICOM:
|
|
case ARPHRD_LOOPBACK:
|
|
handle->linktype = DLT_EN10MB;
|
|
handle->offset = 2;
|
|
break;
|
|
|
|
case ARPHRD_EETHER:
|
|
handle->linktype = DLT_EN3MB;
|
|
break;
|
|
|
|
case ARPHRD_AX25:
|
|
handle->linktype = DLT_AX25_KISS;
|
|
break;
|
|
|
|
case ARPHRD_PRONET:
|
|
handle->linktype = DLT_PRONET;
|
|
break;
|
|
|
|
case ARPHRD_CHAOS:
|
|
handle->linktype = DLT_CHAOS;
|
|
break;
|
|
|
|
#ifndef ARPHRD_IEEE802_TR
|
|
#define ARPHRD_IEEE802_TR 800 /* From Linux 2.4 */
|
|
#endif
|
|
case ARPHRD_IEEE802_TR:
|
|
case ARPHRD_IEEE802:
|
|
handle->linktype = DLT_IEEE802;
|
|
handle->offset = 2;
|
|
break;
|
|
|
|
case ARPHRD_ARCNET:
|
|
handle->linktype = DLT_ARCNET_LINUX;
|
|
break;
|
|
|
|
#ifndef ARPHRD_FDDI /* From Linux 2.2.13 */
|
|
#define ARPHRD_FDDI 774
|
|
#endif
|
|
case ARPHRD_FDDI:
|
|
handle->linktype = DLT_FDDI;
|
|
handle->offset = 3;
|
|
break;
|
|
|
|
#ifndef ARPHRD_ATM /* FIXME: How to #include this? */
|
|
#define ARPHRD_ATM 19
|
|
#endif
|
|
case ARPHRD_ATM:
|
|
/*
|
|
* The Classical IP implementation in ATM for Linux
|
|
* supports both what RFC 1483 calls "LLC Encapsulation",
|
|
* in which each packet has an LLC header, possibly
|
|
* with a SNAP header as well, prepended to it, and
|
|
* what RFC 1483 calls "VC Based Multiplexing", in which
|
|
* different virtual circuits carry different network
|
|
* layer protocols, and no header is prepended to packets.
|
|
*
|
|
* They both have an ARPHRD_ type of ARPHRD_ATM, so
|
|
* you can't use the ARPHRD_ type to find out whether
|
|
* captured packets will have an LLC header, and,
|
|
* while there's a socket ioctl to *set* the encapsulation
|
|
* type, there's no ioctl to *get* the encapsulation type.
|
|
*
|
|
* This means that
|
|
*
|
|
* programs that dissect Linux Classical IP frames
|
|
* would have to check for an LLC header and,
|
|
* depending on whether they see one or not, dissect
|
|
* the frame as LLC-encapsulated or as raw IP (I
|
|
* don't know whether there's any traffic other than
|
|
* IP that would show up on the socket, or whether
|
|
* there's any support for IPv6 in the Linux
|
|
* Classical IP code);
|
|
*
|
|
* filter expressions would have to compile into
|
|
* code that checks for an LLC header and does
|
|
* the right thing.
|
|
*
|
|
* Both of those are a nuisance - and, at least on systems
|
|
* that support PF_PACKET sockets, we don't have to put
|
|
* up with those nuisances; instead, we can just capture
|
|
* in cooked mode. That's what we'll do, if we can.
|
|
* Otherwise, we'll just fail.
|
|
*/
|
|
if (cooked_ok)
|
|
handle->linktype = DLT_LINUX_SLL;
|
|
else
|
|
handle->linktype = -1;
|
|
break;
|
|
|
|
#ifndef ARPHRD_IEEE80211 /* From Linux 2.4.6 */
|
|
#define ARPHRD_IEEE80211 801
|
|
#endif
|
|
case ARPHRD_IEEE80211:
|
|
handle->linktype = DLT_IEEE802_11;
|
|
break;
|
|
|
|
#ifndef ARPHRD_IEEE80211_PRISM /* From Linux 2.4.18 */
|
|
#define ARPHRD_IEEE80211_PRISM 802
|
|
#endif
|
|
case ARPHRD_IEEE80211_PRISM:
|
|
handle->linktype = DLT_PRISM_HEADER;
|
|
break;
|
|
|
|
#ifndef ARPHRD_IEEE80211_RADIOTAP /* new */
|
|
#define ARPHRD_IEEE80211_RADIOTAP 803
|
|
#endif
|
|
case ARPHRD_IEEE80211_RADIOTAP:
|
|
handle->linktype = DLT_IEEE802_11_RADIO;
|
|
break;
|
|
|
|
case ARPHRD_PPP:
|
|
/*
|
|
* Some PPP code in the kernel supplies no link-layer
|
|
* header whatsoever to PF_PACKET sockets; other PPP
|
|
* code supplies PPP link-layer headers ("syncppp.c");
|
|
* some PPP code might supply random link-layer
|
|
* headers (PPP over ISDN - there's code in Ethereal,
|
|
* for example, to cope with PPP-over-ISDN captures
|
|
* with which the Ethereal developers have had to cope,
|
|
* heuristically trying to determine which of the
|
|
* oddball link-layer headers particular packets have).
|
|
*
|
|
* As such, we just punt, and run all PPP interfaces
|
|
* in cooked mode, if we can; otherwise, we just treat
|
|
* it as DLT_RAW, for now - if somebody needs to capture,
|
|
* on a 2.0[.x] kernel, on PPP devices that supply a
|
|
* link-layer header, they'll have to add code here to
|
|
* map to the appropriate DLT_ type (possibly adding a
|
|
* new DLT_ type, if necessary).
|
|
*/
|
|
if (cooked_ok)
|
|
handle->linktype = DLT_LINUX_SLL;
|
|
else {
|
|
/*
|
|
* XXX - handle ISDN types here? We can't fall
|
|
* back on cooked sockets, so we'd have to
|
|
* figure out from the device name what type of
|
|
* link-layer encapsulation it's using, and map
|
|
* that to an appropriate DLT_ value, meaning
|
|
* we'd map "isdnN" devices to DLT_RAW (they
|
|
* supply raw IP packets with no link-layer
|
|
* header) and "isdY" devices to a new DLT_I4L_IP
|
|
* type that has only an Ethernet packet type as
|
|
* a link-layer header.
|
|
*
|
|
* But sometimes we seem to get random crap
|
|
* in the link-layer header when capturing on
|
|
* ISDN devices....
|
|
*/
|
|
handle->linktype = DLT_RAW;
|
|
}
|
|
break;
|
|
|
|
#ifndef ARPHRD_CISCO
|
|
#define ARPHRD_CISCO 513 /* previously ARPHRD_HDLC */
|
|
#endif
|
|
case ARPHRD_CISCO:
|
|
handle->linktype = DLT_C_HDLC;
|
|
break;
|
|
|
|
/* Not sure if this is correct for all tunnels, but it
|
|
* works for CIPE */
|
|
case ARPHRD_TUNNEL:
|
|
#ifndef ARPHRD_SIT
|
|
#define ARPHRD_SIT 776 /* From Linux 2.2.13 */
|
|
#endif
|
|
case ARPHRD_SIT:
|
|
case ARPHRD_CSLIP:
|
|
case ARPHRD_SLIP6:
|
|
case ARPHRD_CSLIP6:
|
|
case ARPHRD_ADAPT:
|
|
case ARPHRD_SLIP:
|
|
#ifndef ARPHRD_RAWHDLC
|
|
#define ARPHRD_RAWHDLC 518
|
|
#endif
|
|
case ARPHRD_RAWHDLC:
|
|
#ifndef ARPHRD_DLCI
|
|
#define ARPHRD_DLCI 15
|
|
#endif
|
|
case ARPHRD_DLCI:
|
|
/*
|
|
* XXX - should some of those be mapped to DLT_LINUX_SLL
|
|
* instead? Should we just map all of them to DLT_LINUX_SLL?
|
|
*/
|
|
handle->linktype = DLT_RAW;
|
|
break;
|
|
|
|
#ifndef ARPHRD_FRAD
|
|
#define ARPHRD_FRAD 770
|
|
#endif
|
|
case ARPHRD_FRAD:
|
|
handle->linktype = DLT_FRELAY;
|
|
break;
|
|
|
|
case ARPHRD_LOCALTLK:
|
|
handle->linktype = DLT_LTALK;
|
|
break;
|
|
|
|
#ifndef ARPHRD_FCPP
|
|
#define ARPHRD_FCPP 784
|
|
#endif
|
|
case ARPHRD_FCPP:
|
|
#ifndef ARPHRD_FCAL
|
|
#define ARPHRD_FCAL 785
|
|
#endif
|
|
case ARPHRD_FCAL:
|
|
#ifndef ARPHRD_FCPL
|
|
#define ARPHRD_FCPL 786
|
|
#endif
|
|
case ARPHRD_FCPL:
|
|
#ifndef ARPHRD_FCFABRIC
|
|
#define ARPHRD_FCFABRIC 787
|
|
#endif
|
|
case ARPHRD_FCFABRIC:
|
|
/*
|
|
* We assume that those all mean RFC 2625 IP-over-
|
|
* Fibre Channel, with the RFC 2625 header at
|
|
* the beginning of the packet.
|
|
*/
|
|
handle->linktype = DLT_IP_OVER_FC;
|
|
break;
|
|
|
|
#ifndef ARPHRD_IRDA
|
|
#define ARPHRD_IRDA 783
|
|
#endif
|
|
case ARPHRD_IRDA:
|
|
/* Don't expect IP packet out of this interfaces... */
|
|
handle->linktype = DLT_LINUX_IRDA;
|
|
/* We need to save packet direction for IrDA decoding,
|
|
* so let's use "Linux-cooked" mode. Jean II */
|
|
//handle->md.cooked = 1;
|
|
break;
|
|
|
|
/* ARPHRD_LAPD is unofficial and randomly allocated, if reallocation
|
|
* is needed, please report it to <daniele@orlandi.com> */
|
|
#ifndef ARPHRD_LAPD
|
|
#define ARPHRD_LAPD 8445
|
|
#endif
|
|
case ARPHRD_LAPD:
|
|
/* Don't expect IP packet out of this interfaces... */
|
|
handle->linktype = DLT_LINUX_LAPD;
|
|
break;
|
|
|
|
#ifndef ARPHRD_NONE
|
|
#define ARPHRD_NONE 0xFFFE
|
|
#endif
|
|
case ARPHRD_NONE:
|
|
/*
|
|
* No link-layer header; packets are just IP
|
|
* packets, so use DLT_RAW.
|
|
*/
|
|
handle->linktype = DLT_RAW;
|
|
break;
|
|
|
|
default:
|
|
handle->linktype = -1;
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* ===== Functions to interface to the newer kernels ================== */
|
|
|
|
/*
|
|
* Try to open a packet socket using the new kernel PF_PACKET interface.
|
|
* Returns 1 on success, 0 on an error that means the new interface isn't
|
|
* present (so the old SOCK_PACKET interface should be tried), and a
|
|
* PCAP_ERROR_ value on an error that means that the old mechanism won't
|
|
* work either (so it shouldn't be tried).
|
|
*/
|
|
static int
|
|
activate_new(pcap_t *handle)
|
|
{
|
|
#ifdef HAVE_PF_PACKET_SOCKETS
|
|
const char *device = handle->opt.source;
|
|
int is_any_device = (strcmp(device, "any") == 0);
|
|
int sock_fd = -1, arptype;
|
|
#ifdef HAVE_PACKET_AUXDATA
|
|
int val;
|
|
#endif
|
|
int err = 0;
|
|
struct packet_mreq mr;
|
|
|
|
/*
|
|
* Open a socket with protocol family packet. If the
|
|
* "any" device was specified, we open a SOCK_DGRAM
|
|
* socket for the cooked interface, otherwise we first
|
|
* try a SOCK_RAW socket for the raw interface.
|
|
*/
|
|
sock_fd = is_any_device ?
|
|
socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_ALL)) :
|
|
socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
|
|
|
|
if (sock_fd == -1) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "socket: %s",
|
|
pcap_strerror(errno) );
|
|
return 0; /* try old mechanism */
|
|
}
|
|
|
|
/* It seems the kernel supports the new interface. */
|
|
handle->md.sock_packet = 0;
|
|
|
|
/*
|
|
* Get the interface index of the loopback device.
|
|
* If the attempt fails, don't fail, just set the
|
|
* "md.lo_ifindex" to -1.
|
|
*
|
|
* XXX - can there be more than one device that loops
|
|
* packets back, i.e. devices other than "lo"? If so,
|
|
* we'd need to find them all, and have an array of
|
|
* indices for them, and check all of them in
|
|
* "pcap_read_packet()".
|
|
*/
|
|
handle->md.lo_ifindex = iface_get_id(sock_fd, "lo", handle->errbuf);
|
|
|
|
/*
|
|
* Default value for offset to align link-layer payload
|
|
* on a 4-byte boundary.
|
|
*/
|
|
handle->offset = 0;
|
|
|
|
/*
|
|
* What kind of frames do we have to deal with? Fall back
|
|
* to cooked mode if we have an unknown interface type
|
|
* or a type we know doesn't work well in raw mode.
|
|
*/
|
|
if (!is_any_device) {
|
|
/* Assume for now we don't need cooked mode. */
|
|
handle->md.cooked = 0;
|
|
|
|
if (handle->opt.rfmon) {
|
|
/*
|
|
* We were asked to turn on monitor mode.
|
|
* Do so before we get the link-layer type,
|
|
* because entering monitor mode could change
|
|
* the link-layer type.
|
|
*/
|
|
err = enter_rfmon_mode(handle, sock_fd, device);
|
|
if (err < 0) {
|
|
/* Hard failure */
|
|
close(sock_fd);
|
|
return err;
|
|
}
|
|
if (err == 0) {
|
|
/*
|
|
* Nothing worked for turning monitor mode
|
|
* on.
|
|
*/
|
|
close(sock_fd);
|
|
return PCAP_ERROR_RFMON_NOTSUP;
|
|
}
|
|
|
|
/*
|
|
* Either monitor mode has been turned on for
|
|
* the device, or we've been given a different
|
|
* device to open for monitor mode. If we've
|
|
* been given a different device, use it.
|
|
*/
|
|
if (handle->md.mondevice != NULL)
|
|
device = handle->md.mondevice;
|
|
}
|
|
arptype = iface_get_arptype(sock_fd, device, handle->errbuf);
|
|
if (arptype < 0) {
|
|
close(sock_fd);
|
|
return arptype;
|
|
}
|
|
map_arphrd_to_dlt(handle, arptype, 1);
|
|
if (handle->linktype == -1 ||
|
|
handle->linktype == DLT_LINUX_SLL ||
|
|
handle->linktype == DLT_LINUX_IRDA ||
|
|
handle->linktype == DLT_LINUX_LAPD ||
|
|
(handle->linktype == DLT_EN10MB &&
|
|
(strncmp("isdn", device, 4) == 0 ||
|
|
strncmp("isdY", device, 4) == 0))) {
|
|
/*
|
|
* Unknown interface type (-1), or a
|
|
* device we explicitly chose to run
|
|
* in cooked mode (e.g., PPP devices),
|
|
* or an ISDN device (whose link-layer
|
|
* type we can only determine by using
|
|
* APIs that may be different on different
|
|
* kernels) - reopen in cooked mode.
|
|
*/
|
|
if (close(sock_fd) == -1) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"close: %s", pcap_strerror(errno));
|
|
return PCAP_ERROR;
|
|
}
|
|
sock_fd = socket(PF_PACKET, SOCK_DGRAM,
|
|
htons(ETH_P_ALL));
|
|
if (sock_fd == -1) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"socket: %s", pcap_strerror(errno));
|
|
return PCAP_ERROR;
|
|
}
|
|
handle->md.cooked = 1;
|
|
|
|
/*
|
|
* Get rid of any link-layer type list
|
|
* we allocated - this only supports cooked
|
|
* capture.
|
|
*/
|
|
if (handle->dlt_list != NULL) {
|
|
free(handle->dlt_list);
|
|
handle->dlt_list = NULL;
|
|
handle->dlt_count = 0;
|
|
}
|
|
|
|
if (handle->linktype == -1) {
|
|
/*
|
|
* Warn that we're falling back on
|
|
* cooked mode; we may want to
|
|
* update "map_arphrd_to_dlt()"
|
|
* to handle the new type.
|
|
*/
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"arptype %d not "
|
|
"supported by libpcap - "
|
|
"falling back to cooked "
|
|
"socket",
|
|
arptype);
|
|
}
|
|
|
|
/*
|
|
* IrDA capture is not a real "cooked" capture,
|
|
* it's IrLAP frames, not IP packets. The
|
|
* same applies to LAPD capture.
|
|
*/
|
|
if (handle->linktype != DLT_LINUX_IRDA &&
|
|
handle->linktype != DLT_LINUX_LAPD)
|
|
handle->linktype = DLT_LINUX_SLL;
|
|
}
|
|
|
|
handle->md.ifindex = iface_get_id(sock_fd, device,
|
|
handle->errbuf);
|
|
if (handle->md.ifindex == -1) {
|
|
close(sock_fd);
|
|
return PCAP_ERROR;
|
|
}
|
|
|
|
if ((err = iface_bind(sock_fd, handle->md.ifindex,
|
|
handle->errbuf)) != 1) {
|
|
close(sock_fd);
|
|
if (err < 0)
|
|
return err;
|
|
else
|
|
return 0; /* try old mechanism */
|
|
}
|
|
} else {
|
|
/*
|
|
* The "any" device.
|
|
*/
|
|
if (handle->opt.rfmon) {
|
|
/*
|
|
* It doesn't support monitor mode.
|
|
*/
|
|
return PCAP_ERROR_RFMON_NOTSUP;
|
|
}
|
|
|
|
/*
|
|
* It uses cooked mode.
|
|
*/
|
|
handle->md.cooked = 1;
|
|
handle->linktype = DLT_LINUX_SLL;
|
|
|
|
/*
|
|
* We're not bound to a device.
|
|
* For now, we're using this as an indication
|
|
* that we can't transmit; stop doing that only
|
|
* if we figure out how to transmit in cooked
|
|
* mode.
|
|
*/
|
|
handle->md.ifindex = -1;
|
|
}
|
|
|
|
/*
|
|
* Select promiscuous mode on if "promisc" is set.
|
|
*
|
|
* Do not turn allmulti mode on if we don't select
|
|
* promiscuous mode - on some devices (e.g., Orinoco
|
|
* wireless interfaces), allmulti mode isn't supported
|
|
* and the driver implements it by turning promiscuous
|
|
* mode on, and that screws up the operation of the
|
|
* card as a normal networking interface, and on no
|
|
* other platform I know of does starting a non-
|
|
* promiscuous capture affect which multicast packets
|
|
* are received by the interface.
|
|
*/
|
|
|
|
/*
|
|
* Hmm, how can we set promiscuous mode on all interfaces?
|
|
* I am not sure if that is possible at all. For now, we
|
|
* silently ignore attempts to turn promiscuous mode on
|
|
* for the "any" device (so you don't have to explicitly
|
|
* disable it in programs such as tcpdump).
|
|
*/
|
|
|
|
if (!is_any_device && handle->opt.promisc) {
|
|
memset(&mr, 0, sizeof(mr));
|
|
mr.mr_ifindex = handle->md.ifindex;
|
|
mr.mr_type = PACKET_MR_PROMISC;
|
|
if (setsockopt(sock_fd, SOL_PACKET, PACKET_ADD_MEMBERSHIP,
|
|
&mr, sizeof(mr)) == -1) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"setsockopt: %s", pcap_strerror(errno));
|
|
close(sock_fd);
|
|
return PCAP_ERROR;
|
|
}
|
|
}
|
|
|
|
/* Enable auxillary data if supported and reserve room for
|
|
* reconstructing VLAN headers. */
|
|
#ifdef HAVE_PACKET_AUXDATA
|
|
val = 1;
|
|
if (setsockopt(sock_fd, SOL_PACKET, PACKET_AUXDATA, &val,
|
|
sizeof(val)) == -1 && errno != ENOPROTOOPT) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"setsockopt: %s", pcap_strerror(errno));
|
|
close(sock_fd);
|
|
return PCAP_ERROR;
|
|
}
|
|
handle->offset += VLAN_TAG_LEN;
|
|
#endif /* HAVE_PACKET_AUXDATA */
|
|
|
|
/*
|
|
* This is a 2.2[.x] or later kernel (we know that
|
|
* because we're not using a SOCK_PACKET socket -
|
|
* PF_PACKET is supported only in 2.2 and later
|
|
* kernels).
|
|
*
|
|
* We can safely pass "recvfrom()" a byte count
|
|
* based on the snapshot length.
|
|
*
|
|
* If we're in cooked mode, make the snapshot length
|
|
* large enough to hold a "cooked mode" header plus
|
|
* 1 byte of packet data (so we don't pass a byte
|
|
* count of 0 to "recvfrom()").
|
|
*/
|
|
if (handle->md.cooked) {
|
|
if (handle->snapshot < SLL_HDR_LEN + 1)
|
|
handle->snapshot = SLL_HDR_LEN + 1;
|
|
}
|
|
handle->bufsize = handle->snapshot;
|
|
|
|
/* Save the socket FD in the pcap structure */
|
|
handle->fd = sock_fd;
|
|
|
|
return 1;
|
|
#else
|
|
strncpy(ebuf,
|
|
"New packet capturing interface not supported by build "
|
|
"environment", PCAP_ERRBUF_SIZE);
|
|
return 0;
|
|
#endif
|
|
}
|
|
|
|
static int
|
|
activate_mmap(pcap_t *handle)
|
|
{
|
|
#ifdef HAVE_PACKET_RING
|
|
int ret;
|
|
|
|
/*
|
|
* Attempt to allocate a buffer to hold the contents of one
|
|
* packet, for use by the oneshot callback.
|
|
*/
|
|
handle->md.oneshot_buffer = malloc(handle->snapshot);
|
|
if (handle->md.oneshot_buffer == NULL) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"can't allocate oneshot buffer: %s",
|
|
pcap_strerror(errno));
|
|
return PCAP_ERROR;
|
|
}
|
|
|
|
if (handle->opt.buffer_size == 0) {
|
|
/* by default request 2M for the ring buffer */
|
|
handle->opt.buffer_size = 2*1024*1024;
|
|
}
|
|
ret = prepare_tpacket_socket(handle);
|
|
if (ret != 1) {
|
|
free(handle->md.oneshot_buffer);
|
|
return ret;
|
|
}
|
|
ret = create_ring(handle);
|
|
if (ret != 1) {
|
|
free(handle->md.oneshot_buffer);
|
|
return ret;
|
|
}
|
|
|
|
/* override some defaults and inherit the other fields from
|
|
* activate_new
|
|
* handle->offset is used to get the current position into the rx ring
|
|
* handle->cc is used to store the ring size */
|
|
handle->read_op = pcap_read_linux_mmap;
|
|
handle->cleanup_op = pcap_cleanup_linux_mmap;
|
|
handle->setfilter_op = pcap_setfilter_linux_mmap;
|
|
handle->setnonblock_op = pcap_setnonblock_mmap;
|
|
handle->getnonblock_op = pcap_getnonblock_mmap;
|
|
handle->oneshot_callback = pcap_oneshot_mmap;
|
|
handle->selectable_fd = handle->fd;
|
|
return 1;
|
|
#else /* HAVE_PACKET_RING */
|
|
return 0;
|
|
#endif /* HAVE_PACKET_RING */
|
|
}
|
|
|
|
#ifdef HAVE_PACKET_RING
|
|
static int
|
|
prepare_tpacket_socket(pcap_t *handle)
|
|
{
|
|
#ifdef HAVE_TPACKET2
|
|
socklen_t len;
|
|
int val;
|
|
#endif
|
|
|
|
handle->md.tp_version = TPACKET_V1;
|
|
handle->md.tp_hdrlen = sizeof(struct tpacket_hdr);
|
|
|
|
#ifdef HAVE_TPACKET2
|
|
/* Probe whether kernel supports TPACKET_V2 */
|
|
val = TPACKET_V2;
|
|
len = sizeof(val);
|
|
if (getsockopt(handle->fd, SOL_PACKET, PACKET_HDRLEN, &val, &len) < 0) {
|
|
if (errno == ENOPROTOOPT)
|
|
return 1; /* no - just drive on */
|
|
|
|
/* Yes - treat as a failure. */
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"can't get TPACKET_V2 header len on packet socket: %s",
|
|
pcap_strerror(errno));
|
|
return -1;
|
|
}
|
|
handle->md.tp_hdrlen = val;
|
|
|
|
val = TPACKET_V2;
|
|
if (setsockopt(handle->fd, SOL_PACKET, PACKET_VERSION, &val,
|
|
sizeof(val)) < 0) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"can't activate TPACKET_V2 on packet socket: %s",
|
|
pcap_strerror(errno));
|
|
return -1;
|
|
}
|
|
handle->md.tp_version = TPACKET_V2;
|
|
|
|
/* Reserve space for VLAN tag reconstruction */
|
|
val = VLAN_TAG_LEN;
|
|
if (setsockopt(handle->fd, SOL_PACKET, PACKET_RESERVE, &val,
|
|
sizeof(val)) < 0) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"can't set up reserve on packet socket: %s",
|
|
pcap_strerror(errno));
|
|
return -1;
|
|
}
|
|
|
|
#endif /* HAVE_TPACKET2 */
|
|
return 1;
|
|
}
|
|
|
|
static int
|
|
create_ring(pcap_t *handle)
|
|
{
|
|
unsigned i, j, frames_per_block;
|
|
struct tpacket_req req;
|
|
|
|
/* Note that with large snapshot (say 64K) only a few frames
|
|
* will be available in the ring even with pretty large ring size
|
|
* (and a lot of memory will be unused).
|
|
* The snap len should be carefully chosen to achive best
|
|
* performance */
|
|
req.tp_frame_size = TPACKET_ALIGN(handle->snapshot +
|
|
TPACKET_ALIGN(handle->md.tp_hdrlen) +
|
|
sizeof(struct sockaddr_ll));
|
|
req.tp_frame_nr = handle->opt.buffer_size/req.tp_frame_size;
|
|
|
|
/* compute the minumum block size that will handle this frame.
|
|
* The block has to be page size aligned.
|
|
* The max block size allowed by the kernel is arch-dependent and
|
|
* it's not explicitly checked here. */
|
|
req.tp_block_size = getpagesize();
|
|
while (req.tp_block_size < req.tp_frame_size)
|
|
req.tp_block_size <<= 1;
|
|
|
|
frames_per_block = req.tp_block_size/req.tp_frame_size;
|
|
|
|
/* ask the kernel to create the ring */
|
|
retry:
|
|
req.tp_block_nr = req.tp_frame_nr / frames_per_block;
|
|
|
|
/* req.tp_frame_nr is requested to match frames_per_block*req.tp_block_nr */
|
|
req.tp_frame_nr = req.tp_block_nr * frames_per_block;
|
|
|
|
if (setsockopt(handle->fd, SOL_PACKET, PACKET_RX_RING,
|
|
(void *) &req, sizeof(req))) {
|
|
if ((errno == ENOMEM) && (req.tp_block_nr > 1)) {
|
|
/*
|
|
* Memory failure; try to reduce the requested ring
|
|
* size.
|
|
*
|
|
* We used to reduce this by half -- do 5% instead.
|
|
* That may result in more iterations and a longer
|
|
* startup, but the user will be much happier with
|
|
* the resulting buffer size.
|
|
*/
|
|
if (req.tp_frame_nr < 20)
|
|
req.tp_frame_nr -= 1;
|
|
else
|
|
req.tp_frame_nr -= req.tp_frame_nr/20;
|
|
goto retry;
|
|
}
|
|
if (errno == ENOPROTOOPT) {
|
|
/*
|
|
* We don't have ring buffer support in this kernel.
|
|
*/
|
|
return 0;
|
|
}
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"can't create rx ring on packet socket: %s",
|
|
pcap_strerror(errno));
|
|
return -1;
|
|
}
|
|
|
|
/* memory map the rx ring */
|
|
handle->md.mmapbuflen = req.tp_block_nr * req.tp_block_size;
|
|
handle->md.mmapbuf = mmap(0, handle->md.mmapbuflen,
|
|
PROT_READ|PROT_WRITE, MAP_SHARED, handle->fd, 0);
|
|
if (handle->md.mmapbuf == MAP_FAILED) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"can't mmap rx ring: %s", pcap_strerror(errno));
|
|
|
|
/* clear the allocated ring on error*/
|
|
destroy_ring(handle);
|
|
return -1;
|
|
}
|
|
|
|
/* allocate a ring for each frame header pointer*/
|
|
handle->cc = req.tp_frame_nr;
|
|
handle->buffer = malloc(handle->cc * sizeof(union thdr *));
|
|
if (!handle->buffer) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"can't allocate ring of frame headers: %s",
|
|
pcap_strerror(errno));
|
|
|
|
destroy_ring(handle);
|
|
return -1;
|
|
}
|
|
|
|
/* fill the header ring with proper frame ptr*/
|
|
handle->offset = 0;
|
|
for (i=0; i<req.tp_block_nr; ++i) {
|
|
void *base = &handle->md.mmapbuf[i*req.tp_block_size];
|
|
for (j=0; j<frames_per_block; ++j, ++handle->offset) {
|
|
RING_GET_FRAME(handle) = base;
|
|
base += req.tp_frame_size;
|
|
}
|
|
}
|
|
|
|
handle->bufsize = req.tp_frame_size;
|
|
handle->offset = 0;
|
|
return 1;
|
|
}
|
|
|
|
/* free all ring related resources*/
|
|
static void
|
|
destroy_ring(pcap_t *handle)
|
|
{
|
|
/* tell the kernel to destroy the ring*/
|
|
struct tpacket_req req;
|
|
memset(&req, 0, sizeof(req));
|
|
setsockopt(handle->fd, SOL_PACKET, PACKET_RX_RING,
|
|
(void *) &req, sizeof(req));
|
|
|
|
/* if ring is mapped, unmap it*/
|
|
if (handle->md.mmapbuf) {
|
|
/* do not test for mmap failure, as we can't recover from any error */
|
|
munmap(handle->md.mmapbuf, handle->md.mmapbuflen);
|
|
handle->md.mmapbuf = NULL;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Special one-shot callback, used for pcap_next() and pcap_next_ex(),
|
|
* for Linux mmapped capture.
|
|
*
|
|
* The problem is that pcap_next() and pcap_next_ex() expect the packet
|
|
* data handed to the callback to be valid after the callback returns,
|
|
* but pcap_read_linux_mmap() has to release that packet as soon as
|
|
* the callback returns (otherwise, the kernel thinks there's still
|
|
* at least one unprocessed packet available in the ring, so a select()
|
|
* will immediately return indicating that there's data to process), so,
|
|
* in the callback, we have to make a copy of the packet.
|
|
*
|
|
* Yes, this means that, if the capture is using the ring buffer, using
|
|
* pcap_next() or pcap_next_ex() requires more copies than using
|
|
* pcap_loop() or pcap_dispatch(). If that bothers you, don't use
|
|
* pcap_next() or pcap_next_ex().
|
|
*/
|
|
static void
|
|
pcap_oneshot_mmap(u_char *user, const struct pcap_pkthdr *h,
|
|
const u_char *bytes)
|
|
{
|
|
struct oneshot_userdata *sp = (struct oneshot_userdata *)user;
|
|
|
|
*sp->hdr = *h;
|
|
memcpy(sp->pd->md.oneshot_buffer, bytes, h->caplen);
|
|
*sp->pkt = sp->pd->md.oneshot_buffer;
|
|
}
|
|
|
|
static void
|
|
pcap_cleanup_linux_mmap( pcap_t *handle )
|
|
{
|
|
destroy_ring(handle);
|
|
if (handle->md.oneshot_buffer != NULL) {
|
|
free(handle->md.oneshot_buffer);
|
|
handle->md.oneshot_buffer = NULL;
|
|
}
|
|
pcap_cleanup_linux(handle);
|
|
}
|
|
|
|
|
|
static int
|
|
pcap_getnonblock_mmap(pcap_t *p, char *errbuf)
|
|
{
|
|
/* use negative value of timeout to indicate non blocking ops */
|
|
return (p->md.timeout<0);
|
|
}
|
|
|
|
static int
|
|
pcap_setnonblock_mmap(pcap_t *p, int nonblock, char *errbuf)
|
|
{
|
|
/* map each value to the corresponding 2's complement, to
|
|
* preserve the timeout value provided with pcap_set_timeout */
|
|
if (nonblock) {
|
|
if (p->md.timeout >= 0) {
|
|
/*
|
|
* Timeout is non-negative, so we're not already
|
|
* in non-blocking mode; set it to the 2's
|
|
* complement, to make it negative, as an
|
|
* indication that we're in non-blocking mode.
|
|
*/
|
|
p->md.timeout = p->md.timeout*-1 - 1;
|
|
}
|
|
} else {
|
|
if (p->md.timeout < 0) {
|
|
/*
|
|
* Timeout is negative, so we're not already
|
|
* in blocking mode; reverse the previous
|
|
* operation, to make the timeout non-negative
|
|
* again.
|
|
*/
|
|
p->md.timeout = (p->md.timeout+1)*-1;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static inline union thdr *
|
|
pcap_get_ring_frame(pcap_t *handle, int status)
|
|
{
|
|
union thdr h;
|
|
|
|
h.raw = RING_GET_FRAME(handle);
|
|
switch (handle->md.tp_version) {
|
|
case TPACKET_V1:
|
|
if (status != (h.h1->tp_status ? TP_STATUS_USER :
|
|
TP_STATUS_KERNEL))
|
|
return NULL;
|
|
break;
|
|
#ifdef HAVE_TPACKET2
|
|
case TPACKET_V2:
|
|
if (status != (h.h2->tp_status ? TP_STATUS_USER :
|
|
TP_STATUS_KERNEL))
|
|
return NULL;
|
|
break;
|
|
#endif
|
|
}
|
|
return h.raw;
|
|
}
|
|
|
|
static int
|
|
pcap_read_linux_mmap(pcap_t *handle, int max_packets, pcap_handler callback,
|
|
u_char *user)
|
|
{
|
|
int pkts = 0;
|
|
|
|
/* wait for frames availability.*/
|
|
if ((handle->md.timeout >= 0) &&
|
|
!pcap_get_ring_frame(handle, TP_STATUS_USER)) {
|
|
struct pollfd pollinfo;
|
|
int ret;
|
|
|
|
pollinfo.fd = handle->fd;
|
|
pollinfo.events = POLLIN;
|
|
|
|
do {
|
|
/* poll() requires a negative timeout to wait forever */
|
|
ret = poll(&pollinfo, 1, (handle->md.timeout > 0)?
|
|
handle->md.timeout: -1);
|
|
if ((ret < 0) && (errno != EINTR)) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"can't poll on packet socket fd %d: %d-%s",
|
|
handle->fd, errno, pcap_strerror(errno));
|
|
return -1;
|
|
}
|
|
/* check for break loop condition on interrupted syscall*/
|
|
if (handle->break_loop) {
|
|
handle->break_loop = 0;
|
|
return -2;
|
|
}
|
|
} while (ret < 0);
|
|
}
|
|
|
|
/* non-positive values of max_packets are used to require all
|
|
* packets currently available in the ring */
|
|
while ((pkts < max_packets) || (max_packets <= 0)) {
|
|
int run_bpf;
|
|
struct sockaddr_ll *sll;
|
|
struct pcap_pkthdr pcaphdr;
|
|
unsigned char *bp;
|
|
union thdr h;
|
|
unsigned int tp_len;
|
|
unsigned int tp_mac;
|
|
unsigned int tp_snaplen;
|
|
unsigned int tp_sec;
|
|
unsigned int tp_usec;
|
|
|
|
h.raw = pcap_get_ring_frame(handle, TP_STATUS_USER);
|
|
if (!h.raw)
|
|
break;
|
|
|
|
switch (handle->md.tp_version) {
|
|
case TPACKET_V1:
|
|
tp_len = h.h1->tp_len;
|
|
tp_mac = h.h1->tp_mac;
|
|
tp_snaplen = h.h1->tp_snaplen;
|
|
tp_sec = h.h1->tp_sec;
|
|
tp_usec = h.h1->tp_usec;
|
|
break;
|
|
#ifdef HAVE_TPACKET2
|
|
case TPACKET_V2:
|
|
tp_len = h.h2->tp_len;
|
|
tp_mac = h.h2->tp_mac;
|
|
tp_snaplen = h.h2->tp_snaplen;
|
|
tp_sec = h.h2->tp_sec;
|
|
tp_usec = h.h2->tp_nsec / 1000;
|
|
break;
|
|
#endif
|
|
default:
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"unsupported tpacket version %d",
|
|
handle->md.tp_version);
|
|
return -1;
|
|
}
|
|
/* perform sanity check on internal offset. */
|
|
if (tp_mac + tp_snaplen > handle->bufsize) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"corrupted frame on kernel ring mac "
|
|
"offset %d + caplen %d > frame len %d",
|
|
tp_mac, tp_snaplen, handle->bufsize);
|
|
return -1;
|
|
}
|
|
|
|
/* run filter on received packet
|
|
* If the kernel filtering is enabled we need to run the
|
|
* filter until all the frames present into the ring
|
|
* at filter creation time are processed.
|
|
* In such case md.use_bpf is used as a counter for the
|
|
* packet we need to filter.
|
|
* Note: alternatively it could be possible to stop applying
|
|
* the filter when the ring became empty, but it can possibly
|
|
* happen a lot later... */
|
|
bp = (unsigned char*)h.raw + tp_mac;
|
|
run_bpf = (!handle->md.use_bpf) ||
|
|
((handle->md.use_bpf>1) && handle->md.use_bpf--);
|
|
if (run_bpf && handle->fcode.bf_insns &&
|
|
(bpf_filter(handle->fcode.bf_insns, bp,
|
|
tp_len, tp_snaplen) == 0))
|
|
goto skip;
|
|
|
|
/*
|
|
* Do checks based on packet direction.
|
|
*/
|
|
sll = (void *)h.raw + TPACKET_ALIGN(handle->md.tp_hdrlen);
|
|
if (sll->sll_pkttype == PACKET_OUTGOING) {
|
|
/*
|
|
* Outgoing packet.
|
|
* If this is from the loopback device, reject it;
|
|
* we'll see the packet as an incoming packet as well,
|
|
* and we don't want to see it twice.
|
|
*/
|
|
if (sll->sll_ifindex == handle->md.lo_ifindex)
|
|
goto skip;
|
|
|
|
/*
|
|
* If the user only wants incoming packets, reject it.
|
|
*/
|
|
if (handle->direction == PCAP_D_IN)
|
|
goto skip;
|
|
} else {
|
|
/*
|
|
* Incoming packet.
|
|
* If the user only wants outgoing packets, reject it.
|
|
*/
|
|
if (handle->direction == PCAP_D_OUT)
|
|
goto skip;
|
|
}
|
|
|
|
/* get required packet info from ring header */
|
|
pcaphdr.ts.tv_sec = tp_sec;
|
|
pcaphdr.ts.tv_usec = tp_usec;
|
|
pcaphdr.caplen = tp_snaplen;
|
|
pcaphdr.len = tp_len;
|
|
|
|
/* if required build in place the sll header*/
|
|
if (handle->md.cooked) {
|
|
struct sll_header *hdrp;
|
|
|
|
/*
|
|
* The kernel should have left us with enough
|
|
* space for an sll header; back up the packet
|
|
* data pointer into that space, as that'll be
|
|
* the beginning of the packet we pass to the
|
|
* callback.
|
|
*/
|
|
bp -= SLL_HDR_LEN;
|
|
|
|
/*
|
|
* Let's make sure that's past the end of
|
|
* the tpacket header, i.e. >=
|
|
* ((u_char *)thdr + TPACKET_HDRLEN), so we
|
|
* don't step on the header when we construct
|
|
* the sll header.
|
|
*/
|
|
if (bp < (u_char *)h.raw +
|
|
TPACKET_ALIGN(handle->md.tp_hdrlen) +
|
|
sizeof(struct sockaddr_ll)) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"cooked-mode frame doesn't have room for sll header");
|
|
return -1;
|
|
}
|
|
|
|
/*
|
|
* OK, that worked; construct the sll header.
|
|
*/
|
|
hdrp = (struct sll_header *)bp;
|
|
hdrp->sll_pkttype = map_packet_type_to_sll_type(
|
|
sll->sll_pkttype);
|
|
hdrp->sll_hatype = htons(sll->sll_hatype);
|
|
hdrp->sll_halen = htons(sll->sll_halen);
|
|
memcpy(hdrp->sll_addr, sll->sll_addr, SLL_ADDRLEN);
|
|
hdrp->sll_protocol = sll->sll_protocol;
|
|
|
|
/* update packet len */
|
|
pcaphdr.caplen += SLL_HDR_LEN;
|
|
pcaphdr.len += SLL_HDR_LEN;
|
|
}
|
|
|
|
#ifdef HAVE_TPACKET2
|
|
if (handle->md.tp_version == TPACKET_V2 && h.h2->tp_vlan_tci &&
|
|
tp_snaplen >= 2 * ETH_ALEN) {
|
|
struct vlan_tag *tag;
|
|
|
|
bp -= VLAN_TAG_LEN;
|
|
memmove(bp, bp + VLAN_TAG_LEN, 2 * ETH_ALEN);
|
|
|
|
tag = (struct vlan_tag *)(bp + 2 * ETH_ALEN);
|
|
tag->vlan_tpid = htons(ETH_P_8021Q);
|
|
tag->vlan_tci = htons(h.h2->tp_vlan_tci);
|
|
|
|
pcaphdr.caplen += VLAN_TAG_LEN;
|
|
pcaphdr.len += VLAN_TAG_LEN;
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* The only way to tell the kernel to cut off the
|
|
* packet at a snapshot length is with a filter program;
|
|
* if there's no filter program, the kernel won't cut
|
|
* the packet off.
|
|
*
|
|
* Trim the snapshot length to be no longer than the
|
|
* specified snapshot length.
|
|
*/
|
|
if (pcaphdr.caplen > handle->snapshot)
|
|
pcaphdr.caplen = handle->snapshot;
|
|
|
|
/* pass the packet to the user */
|
|
pkts++;
|
|
callback(user, &pcaphdr, bp);
|
|
handle->md.packets_read++;
|
|
|
|
skip:
|
|
/* next packet */
|
|
switch (handle->md.tp_version) {
|
|
case TPACKET_V1:
|
|
h.h1->tp_status = TP_STATUS_KERNEL;
|
|
break;
|
|
#ifdef HAVE_TPACKET2
|
|
case TPACKET_V2:
|
|
h.h2->tp_status = TP_STATUS_KERNEL;
|
|
break;
|
|
#endif
|
|
}
|
|
if (++handle->offset >= handle->cc)
|
|
handle->offset = 0;
|
|
|
|
/* check for break loop condition*/
|
|
if (handle->break_loop) {
|
|
handle->break_loop = 0;
|
|
return -2;
|
|
}
|
|
}
|
|
return pkts;
|
|
}
|
|
|
|
static int
|
|
pcap_setfilter_linux_mmap(pcap_t *handle, struct bpf_program *filter)
|
|
{
|
|
int n, offset;
|
|
int ret;
|
|
|
|
/*
|
|
* Don't rewrite "ret" instructions; we don't need to, as
|
|
* we're not reading packets with recvmsg(), and we don't
|
|
* want to, as, by not rewriting them, the kernel can avoid
|
|
* copying extra data.
|
|
*/
|
|
ret = pcap_setfilter_linux_common(handle, filter, 1);
|
|
if (ret < 0)
|
|
return ret;
|
|
|
|
/* if the kernel filter is enabled, we need to apply the filter on
|
|
* all packets present into the ring. Get an upper bound of their number
|
|
*/
|
|
if (!handle->md.use_bpf)
|
|
return ret;
|
|
|
|
/* walk the ring backward and count the free slot */
|
|
offset = handle->offset;
|
|
if (--handle->offset < 0)
|
|
handle->offset = handle->cc - 1;
|
|
for (n=0; n < handle->cc; ++n) {
|
|
if (--handle->offset < 0)
|
|
handle->offset = handle->cc - 1;
|
|
if (!pcap_get_ring_frame(handle, TP_STATUS_KERNEL))
|
|
break;
|
|
}
|
|
|
|
/* be careful to not change current ring position */
|
|
handle->offset = offset;
|
|
|
|
/* store the number of packets currently present in the ring */
|
|
handle->md.use_bpf = 1 + (handle->cc - n);
|
|
return ret;
|
|
}
|
|
|
|
#endif /* HAVE_PACKET_RING */
|
|
|
|
|
|
#ifdef HAVE_PF_PACKET_SOCKETS
|
|
/*
|
|
* Return the index of the given device name. Fill ebuf and return
|
|
* -1 on failure.
|
|
*/
|
|
static int
|
|
iface_get_id(int fd, const char *device, char *ebuf)
|
|
{
|
|
struct ifreq ifr;
|
|
|
|
memset(&ifr, 0, sizeof(ifr));
|
|
strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
|
|
|
|
if (ioctl(fd, SIOCGIFINDEX, &ifr) == -1) {
|
|
snprintf(ebuf, PCAP_ERRBUF_SIZE,
|
|
"SIOCGIFINDEX: %s", pcap_strerror(errno));
|
|
return -1;
|
|
}
|
|
|
|
return ifr.ifr_ifindex;
|
|
}
|
|
|
|
/*
|
|
* Bind the socket associated with FD to the given device.
|
|
* Return 1 on success, 0 if we should try a SOCK_PACKET socket,
|
|
* or a PCAP_ERROR_ value on a hard error.
|
|
*/
|
|
static int
|
|
iface_bind(int fd, int ifindex, char *ebuf)
|
|
{
|
|
struct sockaddr_ll sll;
|
|
int err;
|
|
socklen_t errlen = sizeof(err);
|
|
|
|
memset(&sll, 0, sizeof(sll));
|
|
sll.sll_family = AF_PACKET;
|
|
sll.sll_ifindex = ifindex;
|
|
sll.sll_protocol = htons(ETH_P_ALL);
|
|
|
|
if (bind(fd, (struct sockaddr *) &sll, sizeof(sll)) == -1) {
|
|
if (errno == ENETDOWN) {
|
|
/*
|
|
* Return a "network down" indication, so that
|
|
* the application can report that rather than
|
|
* saying we had a mysterious failure and
|
|
* suggest that they report a problem to the
|
|
* libpcap developers.
|
|
*/
|
|
return PCAP_ERROR_IFACE_NOT_UP;
|
|
} else {
|
|
snprintf(ebuf, PCAP_ERRBUF_SIZE,
|
|
"bind: %s", pcap_strerror(errno));
|
|
return PCAP_ERROR;
|
|
}
|
|
}
|
|
|
|
/* Any pending errors, e.g., network is down? */
|
|
|
|
if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &err, &errlen) == -1) {
|
|
snprintf(ebuf, PCAP_ERRBUF_SIZE,
|
|
"getsockopt: %s", pcap_strerror(errno));
|
|
return 0;
|
|
}
|
|
|
|
if (err == ENETDOWN) {
|
|
/*
|
|
* Return a "network down" indication, so that
|
|
* the application can report that rather than
|
|
* saying we had a mysterious failure and
|
|
* suggest that they report a problem to the
|
|
* libpcap developers.
|
|
*/
|
|
return PCAP_ERROR_IFACE_NOT_UP;
|
|
} else if (err > 0) {
|
|
snprintf(ebuf, PCAP_ERRBUF_SIZE,
|
|
"bind: %s", pcap_strerror(err));
|
|
return 0;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
#ifdef IW_MODE_MONITOR
|
|
/*
|
|
* Check whether the device supports the Wireless Extensions.
|
|
* Returns 1 if it does, 0 if it doesn't, PCAP_ERROR_NO_SUCH_DEVICE
|
|
* if the device doesn't even exist.
|
|
*/
|
|
static int
|
|
has_wext(int sock_fd, const char *device, char *ebuf)
|
|
{
|
|
struct iwreq ireq;
|
|
|
|
strncpy(ireq.ifr_ifrn.ifrn_name, device,
|
|
sizeof ireq.ifr_ifrn.ifrn_name);
|
|
ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
|
|
if (ioctl(sock_fd, SIOCGIWNAME, &ireq) >= 0)
|
|
return 1; /* yes */
|
|
snprintf(ebuf, PCAP_ERRBUF_SIZE,
|
|
"%s: SIOCGIWPRIV: %s", device, pcap_strerror(errno));
|
|
if (errno == ENODEV)
|
|
return PCAP_ERROR_NO_SUCH_DEVICE;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Per me si va ne la citta dolente,
|
|
* Per me si va ne l'etterno dolore,
|
|
* ...
|
|
* Lasciate ogne speranza, voi ch'intrate.
|
|
*
|
|
* XXX - airmon-ng does special stuff with the Orinoco driver and the
|
|
* wlan-ng driver.
|
|
*/
|
|
typedef enum {
|
|
MONITOR_WEXT,
|
|
MONITOR_HOSTAP,
|
|
MONITOR_PRISM,
|
|
MONITOR_PRISM54,
|
|
MONITOR_ACX100,
|
|
MONITOR_RT2500,
|
|
MONITOR_RT2570,
|
|
MONITOR_RT73,
|
|
MONITOR_RTL8XXX
|
|
} monitor_type;
|
|
|
|
/*
|
|
* Use the Wireless Extensions, if we have them, to try to turn monitor mode
|
|
* on if it's not already on.
|
|
*
|
|
* Returns 1 on success, 0 if we don't support the Wireless Extensions
|
|
* on this device, or a PCAP_ERROR_ value if we do support them but
|
|
* we weren't able to turn monitor mode on.
|
|
*/
|
|
static int
|
|
enter_rfmon_mode_wext(pcap_t *handle, int sock_fd, const char *device)
|
|
{
|
|
/*
|
|
* XXX - at least some adapters require non-Wireless Extensions
|
|
* mechanisms to turn monitor mode on.
|
|
*
|
|
* Atheros cards might require that a separate "monitor virtual access
|
|
* point" be created, with later versions of the madwifi driver.
|
|
* airmon-ng does "wlanconfig ath create wlandev {if} wlanmode
|
|
* monitor -bssid", which apparently spits out a line "athN"
|
|
* where "athN" is the monitor mode device. To leave monitor
|
|
* mode, it destroys the monitor mode device.
|
|
*
|
|
* Some Intel Centrino adapters might require private ioctls to get
|
|
* radio headers; the ipw2200 and ipw3945 drivers allow you to
|
|
* configure a separate "rtapN" interface to capture in monitor
|
|
* mode without preventing the adapter from operating normally.
|
|
* (airmon-ng doesn't appear to use that, though.)
|
|
*
|
|
* It would be Truly Wonderful if mac80211 and nl80211 cleaned this
|
|
* up, and if all drivers were converted to mac80211 drivers.
|
|
*
|
|
* If interface {if} is a mac80211 driver, the file
|
|
* /sys/class/net/{if}/phy80211 is a symlink to
|
|
* /sys/class/ieee80211/{phydev}, for some {phydev}.
|
|
*
|
|
* On Fedora 9, with a 2.6.26.3-29 kernel, my Zydas stick, at
|
|
* least, has a "wmaster0" device and a "wlan0" device; the
|
|
* latter is the one with the IP address. Both show up in
|
|
* "tcpdump -D" output. Capturing on the wmaster0 device
|
|
* captures with 802.11 headers.
|
|
*
|
|
* airmon-ng searches through /sys/class/net for devices named
|
|
* monN, starting with mon0; as soon as one *doesn't* exist,
|
|
* it chooses that as the monitor device name. If the "iw"
|
|
* command exists, it does "iw dev {if} interface add {monif}
|
|
* type monitor", where {monif} is the monitor device. It
|
|
* then (sigh) sleeps .1 second, and then configures the
|
|
* device up. Otherwise, if /sys/class/ieee80211/{phydev}/add_iface
|
|
* is a file, it writes {mondev}, without a newline, to that file,
|
|
* and again (sigh) sleeps .1 second, and then iwconfig's that
|
|
* device into monitor mode and configures it up. Otherwise,
|
|
* you can't do monitor mode.
|
|
*
|
|
* All these devices are "glued" together by having the
|
|
* /sys/class/net/{device}/phy80211 links pointing to the same
|
|
* place, so, given a wmaster, wlan, or mon device, you can
|
|
* find the other devices by looking for devices with
|
|
* the same phy80211 link.
|
|
*
|
|
* To turn monitor mode off, delete the monitor interface,
|
|
* either with "iw dev {monif} interface del" or by sending
|
|
* {monif}, with no NL, down /sys/class/ieee80211/{phydev}/remove_iface
|
|
*
|
|
* Note: if you try to create a monitor device named "monN", and
|
|
* there's already a "monN" device, it fails, as least with
|
|
* the netlink interface (which is what iw uses), with a return
|
|
* value of -ENFILE. (Return values are negative errnos.) We
|
|
* could probably use that to find an unused device.
|
|
*/
|
|
int err;
|
|
struct iwreq ireq;
|
|
struct iw_priv_args *priv;
|
|
monitor_type montype;
|
|
int i;
|
|
__u32 cmd;
|
|
int args[2];
|
|
int channel;
|
|
|
|
/*
|
|
* Does this device *support* the Wireless Extensions?
|
|
*/
|
|
err = has_wext(sock_fd, device, handle->errbuf);
|
|
if (err <= 0)
|
|
return err; /* either it doesn't or the device doesn't even exist */
|
|
/*
|
|
* Try to get all the Wireless Extensions private ioctls
|
|
* supported by this device.
|
|
*
|
|
* First, get the size of the buffer we need, by supplying no
|
|
* buffer and a length of 0. If the device supports private
|
|
* ioctls, it should return E2BIG, with ireq.u.data.length set
|
|
* to the length we need. If it doesn't support them, it should
|
|
* return EOPNOTSUPP.
|
|
*/
|
|
memset(&ireq, 0, sizeof ireq);
|
|
strncpy(ireq.ifr_ifrn.ifrn_name, device,
|
|
sizeof ireq.ifr_ifrn.ifrn_name);
|
|
ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
|
|
ireq.u.data.pointer = (void *)args;
|
|
ireq.u.data.length = 0;
|
|
ireq.u.data.flags = 0;
|
|
if (ioctl(sock_fd, SIOCGIWPRIV, &ireq) != -1) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"%s: SIOCGIWPRIV with a zero-length buffer didn't fail!",
|
|
device);
|
|
return PCAP_ERROR;
|
|
}
|
|
if (errno == EOPNOTSUPP) {
|
|
/*
|
|
* No private ioctls, so we assume that there's only one
|
|
* DLT_ for monitor mode.
|
|
*/
|
|
return 0;
|
|
}
|
|
if (errno != E2BIG) {
|
|
/*
|
|
* Failed.
|
|
*/
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"%s: SIOCGIWPRIV: %s", device, pcap_strerror(errno));
|
|
return PCAP_ERROR;
|
|
}
|
|
priv = malloc(ireq.u.data.length * sizeof (struct iw_priv_args));
|
|
if (priv == NULL) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"malloc: %s", pcap_strerror(errno));
|
|
return PCAP_ERROR;
|
|
}
|
|
ireq.u.data.pointer = (void *)priv;
|
|
if (ioctl(sock_fd, SIOCGIWPRIV, &ireq) == -1) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"%s: SIOCGIWPRIV: %s", device, pcap_strerror(errno));
|
|
free(priv);
|
|
return PCAP_ERROR;
|
|
}
|
|
|
|
/*
|
|
* Look for private ioctls to turn monitor mode on or, if
|
|
* monitor mode is on, to set the header type.
|
|
*/
|
|
montype = MONITOR_WEXT;
|
|
cmd = 0;
|
|
for (i = 0; i < ireq.u.data.length; i++) {
|
|
if (strcmp(priv[i].name, "monitor_type") == 0) {
|
|
/*
|
|
* Hostap driver, use this one.
|
|
* Set monitor mode first.
|
|
* You can set it to 0 to get DLT_IEEE80211,
|
|
* 1 to get DLT_PRISM, 2 to get
|
|
* DLT_IEEE80211_RADIO_AVS, and, with more
|
|
* recent versions of the driver, 3 to get
|
|
* DLT_IEEE80211_RADIO.
|
|
*/
|
|
if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT)
|
|
break;
|
|
if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED))
|
|
break;
|
|
if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 1)
|
|
break;
|
|
montype = MONITOR_HOSTAP;
|
|
cmd = priv[i].cmd;
|
|
break;
|
|
}
|
|
if (strcmp(priv[i].name, "set_prismhdr") == 0) {
|
|
/*
|
|
* Prism54 driver, use this one.
|
|
* Set monitor mode first.
|
|
* You can set it to 2 to get DLT_IEEE80211
|
|
* or 3 or get DLT_PRISM.
|
|
*/
|
|
if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT)
|
|
break;
|
|
if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED))
|
|
break;
|
|
if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 1)
|
|
break;
|
|
montype = MONITOR_PRISM54;
|
|
cmd = priv[i].cmd;
|
|
break;
|
|
}
|
|
if (strcmp(priv[i].name, "forceprismheader") == 0) {
|
|
/*
|
|
* RT2570 driver, use this one.
|
|
* Do this after turning monitor mode on.
|
|
* You can set it to 1 to get DLT_PRISM or 2
|
|
* to get DLT_IEEE80211.
|
|
*/
|
|
if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT)
|
|
break;
|
|
if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED))
|
|
break;
|
|
if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 1)
|
|
break;
|
|
montype = MONITOR_RT2570;
|
|
cmd = priv[i].cmd;
|
|
break;
|
|
}
|
|
if (strcmp(priv[i].name, "forceprism") == 0) {
|
|
/*
|
|
* RT73 driver, use this one.
|
|
* Do this after turning monitor mode on.
|
|
* Its argument is a *string*; you can
|
|
* set it to "1" to get DLT_PRISM or "2"
|
|
* to get DLT_IEEE80211.
|
|
*/
|
|
if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_CHAR)
|
|
break;
|
|
if (priv[i].set_args & IW_PRIV_SIZE_FIXED)
|
|
break;
|
|
montype = MONITOR_RT73;
|
|
cmd = priv[i].cmd;
|
|
break;
|
|
}
|
|
if (strcmp(priv[i].name, "prismhdr") == 0) {
|
|
/*
|
|
* One of the RTL8xxx drivers, use this one.
|
|
* It can only be done after monitor mode
|
|
* has been turned on. You can set it to 1
|
|
* to get DLT_PRISM or 0 to get DLT_IEEE80211.
|
|
*/
|
|
if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT)
|
|
break;
|
|
if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED))
|
|
break;
|
|
if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 1)
|
|
break;
|
|
montype = MONITOR_RTL8XXX;
|
|
cmd = priv[i].cmd;
|
|
break;
|
|
}
|
|
if (strcmp(priv[i].name, "rfmontx") == 0) {
|
|
/*
|
|
* RT2500 or RT61 driver, use this one.
|
|
* It has one one-byte parameter; set
|
|
* u.data.length to 1 and u.data.pointer to
|
|
* point to the parameter.
|
|
* It doesn't itself turn monitor mode on.
|
|
* You can set it to 1 to allow transmitting
|
|
* in monitor mode(?) and get DLT_IEEE80211,
|
|
* or set it to 0 to disallow transmitting in
|
|
* monitor mode(?) and get DLT_PRISM.
|
|
*/
|
|
if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT)
|
|
break;
|
|
if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 2)
|
|
break;
|
|
montype = MONITOR_RT2500;
|
|
cmd = priv[i].cmd;
|
|
break;
|
|
}
|
|
if (strcmp(priv[i].name, "monitor") == 0) {
|
|
/*
|
|
* Either ACX100 or hostap, use this one.
|
|
* It turns monitor mode on.
|
|
* If it takes two arguments, it's ACX100;
|
|
* the first argument is 1 for DLT_PRISM
|
|
* or 2 for DLT_IEEE80211, and the second
|
|
* argument is the channel on which to
|
|
* run. If it takes one argument, it's
|
|
* HostAP, and the argument is 2 for
|
|
* DLT_IEEE80211 and 3 for DLT_PRISM.
|
|
*
|
|
* If we see this, we don't quit, as this
|
|
* might be a version of the hostap driver
|
|
* that also supports "monitor_type".
|
|
*/
|
|
if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT)
|
|
break;
|
|
if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED))
|
|
break;
|
|
switch (priv[i].set_args & IW_PRIV_SIZE_MASK) {
|
|
|
|
case 1:
|
|
montype = MONITOR_PRISM;
|
|
cmd = priv[i].cmd;
|
|
break;
|
|
|
|
case 2:
|
|
montype = MONITOR_ACX100;
|
|
cmd = priv[i].cmd;
|
|
break;
|
|
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
free(priv);
|
|
|
|
/*
|
|
* XXX - ipw3945? islism?
|
|
*/
|
|
|
|
/*
|
|
* Get the old mode.
|
|
*/
|
|
strncpy(ireq.ifr_ifrn.ifrn_name, device,
|
|
sizeof ireq.ifr_ifrn.ifrn_name);
|
|
ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
|
|
if (ioctl(sock_fd, SIOCGIWMODE, &ireq) == -1) {
|
|
/*
|
|
* We probably won't be able to set the mode, either.
|
|
*/
|
|
return PCAP_ERROR_RFMON_NOTSUP;
|
|
}
|
|
|
|
/*
|
|
* Is it currently in monitor mode?
|
|
*/
|
|
if (ireq.u.mode == IW_MODE_MONITOR) {
|
|
/*
|
|
* Yes. Just leave things as they are.
|
|
* We don't offer multiple link-layer types, as
|
|
* changing the link-layer type out from under
|
|
* somebody else capturing in monitor mode would
|
|
* be considered rude.
|
|
*/
|
|
return 1;
|
|
}
|
|
/*
|
|
* No. We have to put the adapter into rfmon mode.
|
|
*/
|
|
|
|
/*
|
|
* If we haven't already done so, arrange to have
|
|
* "pcap_close_all()" called when we exit.
|
|
*/
|
|
if (!pcap_do_addexit(handle)) {
|
|
/*
|
|
* "atexit()" failed; don't put the interface
|
|
* in rfmon mode, just give up.
|
|
*/
|
|
return PCAP_ERROR_RFMON_NOTSUP;
|
|
}
|
|
|
|
/*
|
|
* Save the old mode.
|
|
*/
|
|
handle->md.oldmode = ireq.u.mode;
|
|
|
|
/*
|
|
* Put the adapter in rfmon mode. How we do this depends
|
|
* on whether we have a special private ioctl or not.
|
|
*/
|
|
if (montype == MONITOR_PRISM) {
|
|
/*
|
|
* We have the "monitor" private ioctl, but none of
|
|
* the other private ioctls. Use this, and select
|
|
* the Prism header.
|
|
*
|
|
* If it fails, just fall back on SIOCSIWMODE.
|
|
*/
|
|
memset(&ireq, 0, sizeof ireq);
|
|
strncpy(ireq.ifr_ifrn.ifrn_name, device,
|
|
sizeof ireq.ifr_ifrn.ifrn_name);
|
|
ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
|
|
ireq.u.data.length = 1; /* 1 argument */
|
|
args[0] = 3; /* request Prism header */
|
|
memcpy(ireq.u.name, args, IFNAMSIZ);
|
|
if (ioctl(sock_fd, cmd, &ireq) != -1) {
|
|
/*
|
|
* Success.
|
|
* Note that we have to put the old mode back
|
|
* when we close the device.
|
|
*/
|
|
handle->md.must_do_on_close |= MUST_CLEAR_RFMON;
|
|
|
|
/*
|
|
* Add this to the list of pcaps to close
|
|
* when we exit.
|
|
*/
|
|
pcap_add_to_pcaps_to_close(handle);
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Failure. Fall back on SIOCSIWMODE.
|
|
*/
|
|
}
|
|
|
|
/*
|
|
* First, turn monitor mode on.
|
|
*/
|
|
strncpy(ireq.ifr_ifrn.ifrn_name, device,
|
|
sizeof ireq.ifr_ifrn.ifrn_name);
|
|
ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
|
|
ireq.u.mode = IW_MODE_MONITOR;
|
|
if (ioctl(sock_fd, SIOCSIWMODE, &ireq) == -1) {
|
|
/*
|
|
* Scientist, you've failed.
|
|
*/
|
|
return PCAP_ERROR_RFMON_NOTSUP;
|
|
}
|
|
|
|
/*
|
|
* XXX - airmon-ng does "iwconfig {if} key off" after setting
|
|
* monitor mode and setting the channel, and then does
|
|
* "iwconfig up".
|
|
*/
|
|
|
|
/*
|
|
* Now select the appropriate radio header.
|
|
*/
|
|
switch (montype) {
|
|
|
|
case MONITOR_WEXT:
|
|
/*
|
|
* We don't have any private ioctl to set the header.
|
|
*/
|
|
break;
|
|
|
|
case MONITOR_HOSTAP:
|
|
/*
|
|
* Try to select the radiotap header.
|
|
*/
|
|
memset(&ireq, 0, sizeof ireq);
|
|
strncpy(ireq.ifr_ifrn.ifrn_name, device,
|
|
sizeof ireq.ifr_ifrn.ifrn_name);
|
|
ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
|
|
args[0] = 3; /* request radiotap header */
|
|
memcpy(ireq.u.name, args, sizeof (int));
|
|
if (ioctl(sock_fd, cmd, &ireq) != -1)
|
|
break; /* success */
|
|
|
|
/*
|
|
* That failed. Try to select the AVS header.
|
|
*/
|
|
memset(&ireq, 0, sizeof ireq);
|
|
strncpy(ireq.ifr_ifrn.ifrn_name, device,
|
|
sizeof ireq.ifr_ifrn.ifrn_name);
|
|
ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
|
|
args[0] = 2; /* request AVS header */
|
|
memcpy(ireq.u.name, args, sizeof (int));
|
|
if (ioctl(sock_fd, cmd, &ireq) != -1)
|
|
break; /* success */
|
|
|
|
/*
|
|
* That failed. Try to select the Prism header.
|
|
*/
|
|
memset(&ireq, 0, sizeof ireq);
|
|
strncpy(ireq.ifr_ifrn.ifrn_name, device,
|
|
sizeof ireq.ifr_ifrn.ifrn_name);
|
|
ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
|
|
args[0] = 1; /* request Prism header */
|
|
memcpy(ireq.u.name, args, sizeof (int));
|
|
ioctl(sock_fd, cmd, &ireq);
|
|
break;
|
|
|
|
case MONITOR_PRISM:
|
|
/*
|
|
* The private ioctl failed.
|
|
*/
|
|
break;
|
|
|
|
case MONITOR_PRISM54:
|
|
/*
|
|
* Select the Prism header.
|
|
*/
|
|
memset(&ireq, 0, sizeof ireq);
|
|
strncpy(ireq.ifr_ifrn.ifrn_name, device,
|
|
sizeof ireq.ifr_ifrn.ifrn_name);
|
|
ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
|
|
args[0] = 3; /* request Prism header */
|
|
memcpy(ireq.u.name, args, sizeof (int));
|
|
ioctl(sock_fd, cmd, &ireq);
|
|
break;
|
|
|
|
case MONITOR_ACX100:
|
|
/*
|
|
* Get the current channel.
|
|
*/
|
|
memset(&ireq, 0, sizeof ireq);
|
|
strncpy(ireq.ifr_ifrn.ifrn_name, device,
|
|
sizeof ireq.ifr_ifrn.ifrn_name);
|
|
ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
|
|
if (ioctl(sock_fd, SIOCGIWFREQ, &ireq) == -1) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"%s: SIOCGIWFREQ: %s", device,
|
|
pcap_strerror(errno));
|
|
return PCAP_ERROR;
|
|
}
|
|
channel = ireq.u.freq.m;
|
|
|
|
/*
|
|
* Select the Prism header, and set the channel to the
|
|
* current value.
|
|
*/
|
|
memset(&ireq, 0, sizeof ireq);
|
|
strncpy(ireq.ifr_ifrn.ifrn_name, device,
|
|
sizeof ireq.ifr_ifrn.ifrn_name);
|
|
ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
|
|
args[0] = 1; /* request Prism header */
|
|
args[1] = channel; /* set channel */
|
|
memcpy(ireq.u.name, args, 2*sizeof (int));
|
|
ioctl(sock_fd, cmd, &ireq);
|
|
break;
|
|
|
|
case MONITOR_RT2500:
|
|
/*
|
|
* Disallow transmission - that turns on the
|
|
* Prism header.
|
|
*/
|
|
memset(&ireq, 0, sizeof ireq);
|
|
strncpy(ireq.ifr_ifrn.ifrn_name, device,
|
|
sizeof ireq.ifr_ifrn.ifrn_name);
|
|
ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
|
|
args[0] = 0; /* disallow transmitting */
|
|
memcpy(ireq.u.name, args, sizeof (int));
|
|
ioctl(sock_fd, cmd, &ireq);
|
|
break;
|
|
|
|
case MONITOR_RT2570:
|
|
/*
|
|
* Force the Prism header.
|
|
*/
|
|
memset(&ireq, 0, sizeof ireq);
|
|
strncpy(ireq.ifr_ifrn.ifrn_name, device,
|
|
sizeof ireq.ifr_ifrn.ifrn_name);
|
|
ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
|
|
args[0] = 1; /* request Prism header */
|
|
memcpy(ireq.u.name, args, sizeof (int));
|
|
ioctl(sock_fd, cmd, &ireq);
|
|
break;
|
|
|
|
case MONITOR_RT73:
|
|
/*
|
|
* Force the Prism header.
|
|
*/
|
|
memset(&ireq, 0, sizeof ireq);
|
|
strncpy(ireq.ifr_ifrn.ifrn_name, device,
|
|
sizeof ireq.ifr_ifrn.ifrn_name);
|
|
ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
|
|
ireq.u.data.length = 1; /* 1 argument */
|
|
ireq.u.data.pointer = "1";
|
|
ireq.u.data.flags = 0;
|
|
ioctl(sock_fd, cmd, &ireq);
|
|
break;
|
|
|
|
case MONITOR_RTL8XXX:
|
|
/*
|
|
* Force the Prism header.
|
|
*/
|
|
memset(&ireq, 0, sizeof ireq);
|
|
strncpy(ireq.ifr_ifrn.ifrn_name, device,
|
|
sizeof ireq.ifr_ifrn.ifrn_name);
|
|
ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
|
|
args[0] = 1; /* request Prism header */
|
|
memcpy(ireq.u.name, args, sizeof (int));
|
|
ioctl(sock_fd, cmd, &ireq);
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Note that we have to put the old mode back when we
|
|
* close the device.
|
|
*/
|
|
handle->md.must_do_on_close |= MUST_CLEAR_RFMON;
|
|
|
|
/*
|
|
* Add this to the list of pcaps to close when we exit.
|
|
*/
|
|
pcap_add_to_pcaps_to_close(handle);
|
|
|
|
return 1;
|
|
}
|
|
#endif /* IW_MODE_MONITOR */
|
|
|
|
/*
|
|
* Try various mechanisms to enter monitor mode.
|
|
*/
|
|
static int
|
|
enter_rfmon_mode(pcap_t *handle, int sock_fd, const char *device)
|
|
{
|
|
#if defined(HAVE_LIBNL) || defined(IW_MODE_MONITOR)
|
|
int ret;
|
|
#endif
|
|
|
|
#ifdef HAVE_LIBNL
|
|
ret = enter_rfmon_mode_mac80211(handle, sock_fd, device);
|
|
if (ret < 0)
|
|
return ret; /* error attempting to do so */
|
|
if (ret == 1)
|
|
return 1; /* success */
|
|
#endif /* HAVE_LIBNL */
|
|
|
|
#ifdef IW_MODE_MONITOR
|
|
ret = enter_rfmon_mode_wext(handle, sock_fd, device);
|
|
if (ret < 0)
|
|
return ret; /* error attempting to do so */
|
|
if (ret == 1)
|
|
return 1; /* success */
|
|
#endif /* IW_MODE_MONITOR */
|
|
|
|
/*
|
|
* Either none of the mechanisms we know about work or none
|
|
* of those mechanisms are available, so we can't do monitor
|
|
* mode.
|
|
*/
|
|
return 0;
|
|
}
|
|
|
|
#endif /* HAVE_PF_PACKET_SOCKETS */
|
|
|
|
/* ===== Functions to interface to the older kernels ================== */
|
|
|
|
/*
|
|
* Try to open a packet socket using the old kernel interface.
|
|
* Returns 1 on success and a PCAP_ERROR_ value on an error.
|
|
*/
|
|
static int
|
|
activate_old(pcap_t *handle)
|
|
{
|
|
int arptype;
|
|
struct ifreq ifr;
|
|
const char *device = handle->opt.source;
|
|
struct utsname utsname;
|
|
int mtu;
|
|
|
|
/* Open the socket */
|
|
|
|
handle->fd = socket(PF_INET, SOCK_PACKET, htons(ETH_P_ALL));
|
|
if (handle->fd == -1) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"socket: %s", pcap_strerror(errno));
|
|
return PCAP_ERROR_PERM_DENIED;
|
|
}
|
|
|
|
/* It worked - we are using the old interface */
|
|
handle->md.sock_packet = 1;
|
|
|
|
/* ...which means we get the link-layer header. */
|
|
handle->md.cooked = 0;
|
|
|
|
/* Bind to the given device */
|
|
|
|
if (strcmp(device, "any") == 0) {
|
|
strncpy(handle->errbuf, "pcap_activate: The \"any\" device isn't supported on 2.0[.x]-kernel systems",
|
|
PCAP_ERRBUF_SIZE);
|
|
return PCAP_ERROR;
|
|
}
|
|
if (iface_bind_old(handle->fd, device, handle->errbuf) == -1)
|
|
return PCAP_ERROR;
|
|
|
|
/*
|
|
* Try to get the link-layer type.
|
|
*/
|
|
arptype = iface_get_arptype(handle->fd, device, handle->errbuf);
|
|
if (arptype < 0)
|
|
return PCAP_ERROR;
|
|
|
|
/*
|
|
* Try to find the DLT_ type corresponding to that
|
|
* link-layer type.
|
|
*/
|
|
map_arphrd_to_dlt(handle, arptype, 0);
|
|
if (handle->linktype == -1) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"unknown arptype %d", arptype);
|
|
return PCAP_ERROR;
|
|
}
|
|
|
|
/* Go to promisc mode if requested */
|
|
|
|
if (handle->opt.promisc) {
|
|
memset(&ifr, 0, sizeof(ifr));
|
|
strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
|
|
if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) == -1) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"SIOCGIFFLAGS: %s", pcap_strerror(errno));
|
|
return PCAP_ERROR;
|
|
}
|
|
if ((ifr.ifr_flags & IFF_PROMISC) == 0) {
|
|
/*
|
|
* Promiscuous mode isn't currently on,
|
|
* so turn it on, and remember that
|
|
* we should turn it off when the
|
|
* pcap_t is closed.
|
|
*/
|
|
|
|
/*
|
|
* If we haven't already done so, arrange
|
|
* to have "pcap_close_all()" called when
|
|
* we exit.
|
|
*/
|
|
if (!pcap_do_addexit(handle)) {
|
|
/*
|
|
* "atexit()" failed; don't put
|
|
* the interface in promiscuous
|
|
* mode, just give up.
|
|
*/
|
|
return PCAP_ERROR;
|
|
}
|
|
|
|
ifr.ifr_flags |= IFF_PROMISC;
|
|
if (ioctl(handle->fd, SIOCSIFFLAGS, &ifr) == -1) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"SIOCSIFFLAGS: %s",
|
|
pcap_strerror(errno));
|
|
return PCAP_ERROR;
|
|
}
|
|
handle->md.must_do_on_close |= MUST_CLEAR_PROMISC;
|
|
|
|
/*
|
|
* Add this to the list of pcaps
|
|
* to close when we exit.
|
|
*/
|
|
pcap_add_to_pcaps_to_close(handle);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Compute the buffer size.
|
|
*
|
|
* We're using SOCK_PACKET, so this might be a 2.0[.x]
|
|
* kernel, and might require special handling - check.
|
|
*/
|
|
if (uname(&utsname) < 0 ||
|
|
strncmp(utsname.release, "2.0", 3) == 0) {
|
|
/*
|
|
* Either we couldn't find out what kernel release
|
|
* this is, or it's a 2.0[.x] kernel.
|
|
*
|
|
* In the 2.0[.x] kernel, a "recvfrom()" on
|
|
* a SOCK_PACKET socket, with MSG_TRUNC set, will
|
|
* return the number of bytes read, so if we pass
|
|
* a length based on the snapshot length, it'll
|
|
* return the number of bytes from the packet
|
|
* copied to userland, not the actual length
|
|
* of the packet.
|
|
*
|
|
* This means that, for example, the IP dissector
|
|
* in tcpdump will get handed a packet length less
|
|
* than the length in the IP header, and will
|
|
* complain about "truncated-ip".
|
|
*
|
|
* So we don't bother trying to copy from the
|
|
* kernel only the bytes in which we're interested,
|
|
* but instead copy them all, just as the older
|
|
* versions of libpcap for Linux did.
|
|
*
|
|
* The buffer therefore needs to be big enough to
|
|
* hold the largest packet we can get from this
|
|
* device. Unfortunately, we can't get the MRU
|
|
* of the network; we can only get the MTU. The
|
|
* MTU may be too small, in which case a packet larger
|
|
* than the buffer size will be truncated *and* we
|
|
* won't get the actual packet size.
|
|
*
|
|
* However, if the snapshot length is larger than
|
|
* the buffer size based on the MTU, we use the
|
|
* snapshot length as the buffer size, instead;
|
|
* this means that with a sufficiently large snapshot
|
|
* length we won't artificially truncate packets
|
|
* to the MTU-based size.
|
|
*
|
|
* This mess just one of many problems with packet
|
|
* capture on 2.0[.x] kernels; you really want a
|
|
* 2.2[.x] or later kernel if you want packet capture
|
|
* to work well.
|
|
*/
|
|
mtu = iface_get_mtu(handle->fd, device, handle->errbuf);
|
|
if (mtu == -1)
|
|
return PCAP_ERROR;
|
|
handle->bufsize = MAX_LINKHEADER_SIZE + mtu;
|
|
if (handle->bufsize < handle->snapshot)
|
|
handle->bufsize = handle->snapshot;
|
|
} else {
|
|
/*
|
|
* This is a 2.2[.x] or later kernel.
|
|
*
|
|
* We can safely pass "recvfrom()" a byte count
|
|
* based on the snapshot length.
|
|
*/
|
|
handle->bufsize = handle->snapshot;
|
|
}
|
|
|
|
/*
|
|
* Default value for offset to align link-layer payload
|
|
* on a 4-byte boundary.
|
|
*/
|
|
handle->offset = 0;
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Bind the socket associated with FD to the given device using the
|
|
* interface of the old kernels.
|
|
*/
|
|
static int
|
|
iface_bind_old(int fd, const char *device, char *ebuf)
|
|
{
|
|
struct sockaddr saddr;
|
|
int err;
|
|
socklen_t errlen = sizeof(err);
|
|
|
|
memset(&saddr, 0, sizeof(saddr));
|
|
strncpy(saddr.sa_data, device, sizeof(saddr.sa_data));
|
|
if (bind(fd, &saddr, sizeof(saddr)) == -1) {
|
|
snprintf(ebuf, PCAP_ERRBUF_SIZE,
|
|
"bind: %s", pcap_strerror(errno));
|
|
return -1;
|
|
}
|
|
|
|
/* Any pending errors, e.g., network is down? */
|
|
|
|
if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &err, &errlen) == -1) {
|
|
snprintf(ebuf, PCAP_ERRBUF_SIZE,
|
|
"getsockopt: %s", pcap_strerror(errno));
|
|
return -1;
|
|
}
|
|
|
|
if (err > 0) {
|
|
snprintf(ebuf, PCAP_ERRBUF_SIZE,
|
|
"bind: %s", pcap_strerror(err));
|
|
return -1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
/* ===== System calls available on all supported kernels ============== */
|
|
|
|
/*
|
|
* Query the kernel for the MTU of the given interface.
|
|
*/
|
|
static int
|
|
iface_get_mtu(int fd, const char *device, char *ebuf)
|
|
{
|
|
struct ifreq ifr;
|
|
|
|
if (!device)
|
|
return BIGGER_THAN_ALL_MTUS;
|
|
|
|
memset(&ifr, 0, sizeof(ifr));
|
|
strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
|
|
|
|
if (ioctl(fd, SIOCGIFMTU, &ifr) == -1) {
|
|
snprintf(ebuf, PCAP_ERRBUF_SIZE,
|
|
"SIOCGIFMTU: %s", pcap_strerror(errno));
|
|
return -1;
|
|
}
|
|
|
|
return ifr.ifr_mtu;
|
|
}
|
|
|
|
/*
|
|
* Get the hardware type of the given interface as ARPHRD_xxx constant.
|
|
*/
|
|
static int
|
|
iface_get_arptype(int fd, const char *device, char *ebuf)
|
|
{
|
|
struct ifreq ifr;
|
|
|
|
memset(&ifr, 0, sizeof(ifr));
|
|
strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
|
|
|
|
if (ioctl(fd, SIOCGIFHWADDR, &ifr) == -1) {
|
|
snprintf(ebuf, PCAP_ERRBUF_SIZE,
|
|
"SIOCGIFHWADDR: %s", pcap_strerror(errno));
|
|
if (errno == ENODEV) {
|
|
/*
|
|
* No such device.
|
|
*/
|
|
return PCAP_ERROR_NO_SUCH_DEVICE;
|
|
}
|
|
return PCAP_ERROR;
|
|
}
|
|
|
|
return ifr.ifr_hwaddr.sa_family;
|
|
}
|
|
|
|
#ifdef SO_ATTACH_FILTER
|
|
static int
|
|
fix_program(pcap_t *handle, struct sock_fprog *fcode, int is_mmapped)
|
|
{
|
|
size_t prog_size;
|
|
register int i;
|
|
register struct bpf_insn *p;
|
|
struct bpf_insn *f;
|
|
int len;
|
|
|
|
/*
|
|
* Make a copy of the filter, and modify that copy if
|
|
* necessary.
|
|
*/
|
|
prog_size = sizeof(*handle->fcode.bf_insns) * handle->fcode.bf_len;
|
|
len = handle->fcode.bf_len;
|
|
f = (struct bpf_insn *)malloc(prog_size);
|
|
if (f == NULL) {
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"malloc: %s", pcap_strerror(errno));
|
|
return -1;
|
|
}
|
|
memcpy(f, handle->fcode.bf_insns, prog_size);
|
|
fcode->len = len;
|
|
fcode->filter = (struct sock_filter *) f;
|
|
|
|
for (i = 0; i < len; ++i) {
|
|
p = &f[i];
|
|
/*
|
|
* What type of instruction is this?
|
|
*/
|
|
switch (BPF_CLASS(p->code)) {
|
|
|
|
case BPF_RET:
|
|
/*
|
|
* It's a return instruction; are we capturing
|
|
* in memory-mapped mode?
|
|
*/
|
|
if (!is_mmapped) {
|
|
/*
|
|
* No; is the snapshot length a constant,
|
|
* rather than the contents of the
|
|
* accumulator?
|
|
*/
|
|
if (BPF_MODE(p->code) == BPF_K) {
|
|
/*
|
|
* Yes - if the value to be returned,
|
|
* i.e. the snapshot length, is
|
|
* anything other than 0, make it
|
|
* 65535, so that the packet is
|
|
* truncated by "recvfrom()",
|
|
* not by the filter.
|
|
*
|
|
* XXX - there's nothing we can
|
|
* easily do if it's getting the
|
|
* value from the accumulator; we'd
|
|
* have to insert code to force
|
|
* non-zero values to be 65535.
|
|
*/
|
|
if (p->k != 0)
|
|
p->k = 65535;
|
|
}
|
|
}
|
|
break;
|
|
|
|
case BPF_LD:
|
|
case BPF_LDX:
|
|
/*
|
|
* It's a load instruction; is it loading
|
|
* from the packet?
|
|
*/
|
|
switch (BPF_MODE(p->code)) {
|
|
|
|
case BPF_ABS:
|
|
case BPF_IND:
|
|
case BPF_MSH:
|
|
/*
|
|
* Yes; are we in cooked mode?
|
|
*/
|
|
if (handle->md.cooked) {
|
|
/*
|
|
* Yes, so we need to fix this
|
|
* instruction.
|
|
*/
|
|
if (fix_offset(p) < 0) {
|
|
/*
|
|
* We failed to do so.
|
|
* Return 0, so our caller
|
|
* knows to punt to userland.
|
|
*/
|
|
return 0;
|
|
}
|
|
}
|
|
break;
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
return 1; /* we succeeded */
|
|
}
|
|
|
|
static int
|
|
fix_offset(struct bpf_insn *p)
|
|
{
|
|
/*
|
|
* What's the offset?
|
|
*/
|
|
if (p->k >= SLL_HDR_LEN) {
|
|
/*
|
|
* It's within the link-layer payload; that starts at an
|
|
* offset of 0, as far as the kernel packet filter is
|
|
* concerned, so subtract the length of the link-layer
|
|
* header.
|
|
*/
|
|
p->k -= SLL_HDR_LEN;
|
|
} else if (p->k == 14) {
|
|
/*
|
|
* It's the protocol field; map it to the special magic
|
|
* kernel offset for that field.
|
|
*/
|
|
p->k = SKF_AD_OFF + SKF_AD_PROTOCOL;
|
|
} else {
|
|
/*
|
|
* It's within the header, but it's not one of those
|
|
* fields; we can't do that in the kernel, so punt
|
|
* to userland.
|
|
*/
|
|
return -1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int
|
|
set_kernel_filter(pcap_t *handle, struct sock_fprog *fcode)
|
|
{
|
|
int total_filter_on = 0;
|
|
int save_mode;
|
|
int ret;
|
|
int save_errno;
|
|
|
|
/*
|
|
* The socket filter code doesn't discard all packets queued
|
|
* up on the socket when the filter is changed; this means
|
|
* that packets that don't match the new filter may show up
|
|
* after the new filter is put onto the socket, if those
|
|
* packets haven't yet been read.
|
|
*
|
|
* This means, for example, that if you do a tcpdump capture
|
|
* with a filter, the first few packets in the capture might
|
|
* be packets that wouldn't have passed the filter.
|
|
*
|
|
* We therefore discard all packets queued up on the socket
|
|
* when setting a kernel filter. (This isn't an issue for
|
|
* userland filters, as the userland filtering is done after
|
|
* packets are queued up.)
|
|
*
|
|
* To flush those packets, we put the socket in read-only mode,
|
|
* and read packets from the socket until there are no more to
|
|
* read.
|
|
*
|
|
* In order to keep that from being an infinite loop - i.e.,
|
|
* to keep more packets from arriving while we're draining
|
|
* the queue - we put the "total filter", which is a filter
|
|
* that rejects all packets, onto the socket before draining
|
|
* the queue.
|
|
*
|
|
* This code deliberately ignores any errors, so that you may
|
|
* get bogus packets if an error occurs, rather than having
|
|
* the filtering done in userland even if it could have been
|
|
* done in the kernel.
|
|
*/
|
|
if (setsockopt(handle->fd, SOL_SOCKET, SO_ATTACH_FILTER,
|
|
&total_fcode, sizeof(total_fcode)) == 0) {
|
|
char drain[1];
|
|
|
|
/*
|
|
* Note that we've put the total filter onto the socket.
|
|
*/
|
|
total_filter_on = 1;
|
|
|
|
/*
|
|
* Save the socket's current mode, and put it in
|
|
* non-blocking mode; we drain it by reading packets
|
|
* until we get an error (which is normally a
|
|
* "nothing more to be read" error).
|
|
*/
|
|
save_mode = fcntl(handle->fd, F_GETFL, 0);
|
|
if (save_mode != -1 &&
|
|
fcntl(handle->fd, F_SETFL, save_mode | O_NONBLOCK) >= 0) {
|
|
while (recv(handle->fd, &drain, sizeof drain,
|
|
MSG_TRUNC) >= 0)
|
|
;
|
|
save_errno = errno;
|
|
fcntl(handle->fd, F_SETFL, save_mode);
|
|
if (save_errno != EAGAIN) {
|
|
/* Fatal error */
|
|
reset_kernel_filter(handle);
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
"recv: %s", pcap_strerror(save_errno));
|
|
return -2;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Now attach the new filter.
|
|
*/
|
|
ret = setsockopt(handle->fd, SOL_SOCKET, SO_ATTACH_FILTER,
|
|
fcode, sizeof(*fcode));
|
|
if (ret == -1 && total_filter_on) {
|
|
/*
|
|
* Well, we couldn't set that filter on the socket,
|
|
* but we could set the total filter on the socket.
|
|
*
|
|
* This could, for example, mean that the filter was
|
|
* too big to put into the kernel, so we'll have to
|
|
* filter in userland; in any case, we'll be doing
|
|
* filtering in userland, so we need to remove the
|
|
* total filter so we see packets.
|
|
*/
|
|
save_errno = errno;
|
|
|
|
/*
|
|
* XXX - if this fails, we're really screwed;
|
|
* we have the total filter on the socket,
|
|
* and it won't come off. What do we do then?
|
|
*/
|
|
reset_kernel_filter(handle);
|
|
|
|
errno = save_errno;
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
static int
|
|
reset_kernel_filter(pcap_t *handle)
|
|
{
|
|
/*
|
|
* setsockopt() barfs unless it get a dummy parameter.
|
|
* valgrind whines unless the value is initialized,
|
|
* as it has no idea that setsockopt() ignores its
|
|
* parameter.
|
|
*/
|
|
int dummy = 0;
|
|
|
|
return setsockopt(handle->fd, SOL_SOCKET, SO_DETACH_FILTER,
|
|
&dummy, sizeof(dummy));
|
|
}
|
|
#endif
|