![Paul Moore](/assets/img/avatar_default.png)
Now that the SELinux NetLabel "base SID" is always the netmsg initial SID we can do a big optimization - caching the SID and not just the MLS attributes. This not only saves a lot of per-packet memory allocations and copies but it has a nice side effect of removing a chunk of code. Signed-off-by: Paul Moore <paul.moore@hp.com> Signed-off-by: James Morris <jmorris@namei.org>
403 lines
10 KiB
C
403 lines
10 KiB
C
/*
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* SELinux NetLabel Support
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*
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* This file provides the necessary glue to tie NetLabel into the SELinux
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* subsystem.
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*
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* Author: Paul Moore <paul.moore@hp.com>
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*
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*/
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/*
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* (c) Copyright Hewlett-Packard Development Company, L.P., 2007
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
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* the GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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*/
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#include <linux/spinlock.h>
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#include <linux/rcupdate.h>
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#include <net/sock.h>
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#include <net/netlabel.h>
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#include "objsec.h"
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#include "security.h"
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/**
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* selinux_netlbl_sidlookup_cached - Cache a SID lookup
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* @skb: the packet
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* @secattr: the NetLabel security attributes
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* @sid: the SID
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*
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* Description:
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* Query the SELinux security server to lookup the correct SID for the given
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* security attributes. If the query is successful, cache the result to speed
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* up future lookups. Returns zero on success, negative values on failure.
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*
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*/
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static int selinux_netlbl_sidlookup_cached(struct sk_buff *skb,
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struct netlbl_lsm_secattr *secattr,
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u32 *sid)
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{
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int rc;
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rc = security_netlbl_secattr_to_sid(secattr, sid);
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if (rc == 0 &&
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(secattr->flags & NETLBL_SECATTR_CACHEABLE) &&
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(secattr->flags & NETLBL_SECATTR_CACHE))
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netlbl_cache_add(skb, secattr);
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return rc;
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}
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/**
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* selinux_netlbl_sock_setsid - Label a socket using the NetLabel mechanism
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* @sk: the socket to label
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* @sid: the SID to use
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*
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* Description:
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* Attempt to label a socket using the NetLabel mechanism using the given
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* SID. Returns zero values on success, negative values on failure. The
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* caller is responsibile for calling rcu_read_lock() before calling this
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* this function and rcu_read_unlock() after this function returns.
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*
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*/
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static int selinux_netlbl_sock_setsid(struct sock *sk, u32 sid)
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{
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int rc;
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struct sk_security_struct *sksec = sk->sk_security;
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struct netlbl_lsm_secattr secattr;
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netlbl_secattr_init(&secattr);
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rc = security_netlbl_sid_to_secattr(sid, &secattr);
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if (rc != 0)
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goto sock_setsid_return;
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rc = netlbl_sock_setattr(sk, &secattr);
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if (rc == 0) {
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spin_lock_bh(&sksec->nlbl_lock);
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sksec->nlbl_state = NLBL_LABELED;
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spin_unlock_bh(&sksec->nlbl_lock);
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}
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sock_setsid_return:
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netlbl_secattr_destroy(&secattr);
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return rc;
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}
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/**
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* selinux_netlbl_cache_invalidate - Invalidate the NetLabel cache
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*
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* Description:
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* Invalidate the NetLabel security attribute mapping cache.
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*
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*/
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void selinux_netlbl_cache_invalidate(void)
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{
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netlbl_cache_invalidate();
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}
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/**
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* selinux_netlbl_sk_security_reset - Reset the NetLabel fields
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* @ssec: the sk_security_struct
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* @family: the socket family
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*
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* Description:
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* Called when the NetLabel state of a sk_security_struct needs to be reset.
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* The caller is responsibile for all the NetLabel sk_security_struct locking.
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*
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*/
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void selinux_netlbl_sk_security_reset(struct sk_security_struct *ssec,
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int family)
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{
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if (family == PF_INET)
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ssec->nlbl_state = NLBL_REQUIRE;
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else
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ssec->nlbl_state = NLBL_UNSET;
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}
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/**
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* selinux_netlbl_sk_security_init - Setup the NetLabel fields
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* @ssec: the sk_security_struct
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* @family: the socket family
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*
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* Description:
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* Called when a new sk_security_struct is allocated to initialize the NetLabel
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* fields.
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*
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*/
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void selinux_netlbl_sk_security_init(struct sk_security_struct *ssec,
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int family)
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{
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/* No locking needed, we are the only one who has access to ssec */
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selinux_netlbl_sk_security_reset(ssec, family);
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spin_lock_init(&ssec->nlbl_lock);
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}
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/**
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* selinux_netlbl_sk_security_clone - Copy the NetLabel fields
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* @ssec: the original sk_security_struct
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* @newssec: the cloned sk_security_struct
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*
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* Description:
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* Clone the NetLabel specific sk_security_struct fields from @ssec to
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* @newssec.
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*
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*/
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void selinux_netlbl_sk_security_clone(struct sk_security_struct *ssec,
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struct sk_security_struct *newssec)
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{
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/* We don't need to take newssec->nlbl_lock because we are the only
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* thread with access to newssec, but we do need to take the RCU read
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* lock as other threads could have access to ssec */
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rcu_read_lock();
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selinux_netlbl_sk_security_reset(newssec, ssec->sk->sk_family);
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rcu_read_unlock();
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}
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/**
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* selinux_netlbl_skbuff_getsid - Get the sid of a packet using NetLabel
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* @skb: the packet
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* @family: protocol family
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* @type: NetLabel labeling protocol type
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* @sid: the SID
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*
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* Description:
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* Call the NetLabel mechanism to get the security attributes of the given
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* packet and use those attributes to determine the correct context/SID to
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* assign to the packet. Returns zero on success, negative values on failure.
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*
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*/
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int selinux_netlbl_skbuff_getsid(struct sk_buff *skb,
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u16 family,
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u32 *type,
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u32 *sid)
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{
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int rc;
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struct netlbl_lsm_secattr secattr;
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if (!netlbl_enabled()) {
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*sid = SECSID_NULL;
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return 0;
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}
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netlbl_secattr_init(&secattr);
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rc = netlbl_skbuff_getattr(skb, family, &secattr);
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if (rc == 0 && secattr.flags != NETLBL_SECATTR_NONE)
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rc = selinux_netlbl_sidlookup_cached(skb, &secattr, sid);
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else
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*sid = SECSID_NULL;
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*type = secattr.type;
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netlbl_secattr_destroy(&secattr);
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return rc;
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}
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/**
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* selinux_netlbl_sock_graft - Netlabel the new socket
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* @sk: the new connection
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* @sock: the new socket
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*
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* Description:
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* The connection represented by @sk is being grafted onto @sock so set the
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* socket's NetLabel to match the SID of @sk.
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*
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*/
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void selinux_netlbl_sock_graft(struct sock *sk, struct socket *sock)
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{
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struct sk_security_struct *sksec = sk->sk_security;
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struct netlbl_lsm_secattr secattr;
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u32 nlbl_peer_sid;
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rcu_read_lock();
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if (sksec->nlbl_state != NLBL_REQUIRE) {
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rcu_read_unlock();
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return;
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}
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netlbl_secattr_init(&secattr);
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if (netlbl_sock_getattr(sk, &secattr) == 0 &&
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secattr.flags != NETLBL_SECATTR_NONE &&
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security_netlbl_secattr_to_sid(&secattr, &nlbl_peer_sid) == 0)
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sksec->peer_sid = nlbl_peer_sid;
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netlbl_secattr_destroy(&secattr);
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/* Try to set the NetLabel on the socket to save time later, if we fail
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* here we will pick up the pieces in later calls to
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* selinux_netlbl_inode_permission(). */
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selinux_netlbl_sock_setsid(sk, sksec->sid);
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rcu_read_unlock();
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}
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/**
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* selinux_netlbl_socket_post_create - Label a socket using NetLabel
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* @sock: the socket to label
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*
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* Description:
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* Attempt to label a socket using the NetLabel mechanism using the given
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* SID. Returns zero values on success, negative values on failure.
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*
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*/
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int selinux_netlbl_socket_post_create(struct socket *sock)
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{
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int rc = 0;
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struct sock *sk = sock->sk;
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struct sk_security_struct *sksec = sk->sk_security;
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rcu_read_lock();
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if (sksec->nlbl_state == NLBL_REQUIRE)
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rc = selinux_netlbl_sock_setsid(sk, sksec->sid);
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rcu_read_unlock();
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return rc;
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}
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/**
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* selinux_netlbl_inode_permission - Verify the socket is NetLabel labeled
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* @inode: the file descriptor's inode
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* @mask: the permission mask
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*
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* Description:
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* Looks at a file's inode and if it is marked as a socket protected by
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* NetLabel then verify that the socket has been labeled, if not try to label
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* the socket now with the inode's SID. Returns zero on success, negative
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* values on failure.
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*
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*/
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int selinux_netlbl_inode_permission(struct inode *inode, int mask)
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{
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int rc;
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struct sock *sk;
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struct socket *sock;
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struct sk_security_struct *sksec;
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if (!S_ISSOCK(inode->i_mode) ||
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((mask & (MAY_WRITE | MAY_APPEND)) == 0))
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return 0;
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sock = SOCKET_I(inode);
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sk = sock->sk;
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sksec = sk->sk_security;
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rcu_read_lock();
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if (sksec->nlbl_state != NLBL_REQUIRE) {
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rcu_read_unlock();
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return 0;
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}
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local_bh_disable();
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bh_lock_sock_nested(sk);
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rc = selinux_netlbl_sock_setsid(sk, sksec->sid);
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bh_unlock_sock(sk);
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local_bh_enable();
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rcu_read_unlock();
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return rc;
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}
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/**
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* selinux_netlbl_sock_rcv_skb - Do an inbound access check using NetLabel
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* @sksec: the sock's sk_security_struct
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* @skb: the packet
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* @family: protocol family
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* @ad: the audit data
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*
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* Description:
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* Fetch the NetLabel security attributes from @skb and perform an access check
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* against the receiving socket. Returns zero on success, negative values on
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* error.
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*
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*/
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int selinux_netlbl_sock_rcv_skb(struct sk_security_struct *sksec,
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struct sk_buff *skb,
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u16 family,
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struct avc_audit_data *ad)
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{
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int rc;
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u32 nlbl_sid;
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u32 perm;
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struct netlbl_lsm_secattr secattr;
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if (!netlbl_enabled())
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return 0;
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netlbl_secattr_init(&secattr);
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rc = netlbl_skbuff_getattr(skb, family, &secattr);
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if (rc == 0 && secattr.flags != NETLBL_SECATTR_NONE)
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rc = selinux_netlbl_sidlookup_cached(skb, &secattr, &nlbl_sid);
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else
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nlbl_sid = SECINITSID_UNLABELED;
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netlbl_secattr_destroy(&secattr);
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if (rc != 0)
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return rc;
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switch (sksec->sclass) {
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case SECCLASS_UDP_SOCKET:
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perm = UDP_SOCKET__RECVFROM;
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break;
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case SECCLASS_TCP_SOCKET:
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perm = TCP_SOCKET__RECVFROM;
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break;
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default:
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perm = RAWIP_SOCKET__RECVFROM;
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}
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rc = avc_has_perm(sksec->sid, nlbl_sid, sksec->sclass, perm, ad);
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if (rc == 0)
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return 0;
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if (nlbl_sid != SECINITSID_UNLABELED)
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netlbl_skbuff_err(skb, rc);
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return rc;
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}
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/**
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* selinux_netlbl_socket_setsockopt - Do not allow users to remove a NetLabel
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* @sock: the socket
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* @level: the socket level or protocol
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* @optname: the socket option name
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*
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* Description:
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* Check the setsockopt() call and if the user is trying to replace the IP
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* options on a socket and a NetLabel is in place for the socket deny the
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* access; otherwise allow the access. Returns zero when the access is
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* allowed, -EACCES when denied, and other negative values on error.
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*
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*/
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int selinux_netlbl_socket_setsockopt(struct socket *sock,
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int level,
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int optname)
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{
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int rc = 0;
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struct sock *sk = sock->sk;
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struct sk_security_struct *sksec = sk->sk_security;
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struct netlbl_lsm_secattr secattr;
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rcu_read_lock();
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if (level == IPPROTO_IP && optname == IP_OPTIONS &&
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sksec->nlbl_state == NLBL_LABELED) {
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netlbl_secattr_init(&secattr);
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lock_sock(sk);
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rc = netlbl_sock_getattr(sk, &secattr);
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release_sock(sk);
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if (rc == 0 && secattr.flags != NETLBL_SECATTR_NONE)
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rc = -EACCES;
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netlbl_secattr_destroy(&secattr);
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}
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rcu_read_unlock();
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return rc;
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}
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