wireshark/epan/dissectors/packet-netlink.c

/* packet-netlink.c
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

/* http://www.tcpdump.org/linktypes/LINKTYPE_NETLINK.html */

#define NEW_PROTO_TREE_API

#include "config.h"

#include <epan/packet.h>
#include <epan/arptypes.h>
#include <wiretap/wtap.h>

#include "packet-netlink.h"

void proto_register_netlink(void);
void proto_reg_handoff_netlink(void);

/*
 * A DLT_LINUX_SLL fake link-layer header.
 */
#define SLL_HEADER_SIZE	16		/* total header length */

static const value_string netlink_family_vals[] = {
	{ WS_NETLINK_ROUTE,          "Route" },
	{ WS_NETLINK_UNUSED,         "Unused" },
	{ WS_NETLINK_USERSOCK,       "User-mode socket protocols" },
	{ WS_NETLINK_FIREWALL,       "Unused (formerly: ip_queue)" },
	{ WS_NETLINK_SOCK_DIAG,      "Socket monitoring" },
	{ WS_NETLINK_NFLOG,          "Netfilter ULOG" },
	{ WS_NETLINK_XFRM,           "IPsec" },
	{ WS_NETLINK_SELINUX,        "SELinux events" },
	{ WS_NETLINK_ISCSI,          "Open-iSCSI" },
	{ WS_NETLINK_AUDIT,          "Auditing" },
	{ WS_NETLINK_FIB_LOOKUP,     "FIB lookup" },
	{ WS_NETLINK_CONNECTOR,      "Kernel connector" },
	{ WS_NETLINK_NETFILTER,      "Netfilter" },
	{ WS_NETLINK_IP6_FW,         "Unused (formerly: ip6_queue)" },
	{ WS_NETLINK_DNRTMSG,        "DECnet routing messages" },
	{ WS_NETLINK_KOBJECT_UEVENT, "Kernel messages to userspace" },
	{ WS_NETLINK_GENERIC,        "Generic" },
	{ WS_NETLINK_SCSITRANSPORT,  "SCSI Transports" },
	{ WS_NETLINK_ECRYPTFS,       "ecryptfs" },
	{ WS_NETLINK_RDMA,           "RDMA" },
	{ WS_NETLINK_CRYPTO,         "Crypto layer" },
	{ 0, NULL }
};

value_string_ext netlink_family_vals_ext = VALUE_STRING_EXT_INIT(netlink_family_vals);

static const value_string type_vals[] = {
	{ WS_NLMSG_NOOP,    "Nothing" },
	{ WS_NLMSG_ERROR,   "Error" },
	{ WS_NLMSG_DONE,    "End of a dump" },
	{ WS_NLMSG_OVERRUN, "Data lost" },
	{ 0, NULL }
};

static const value_string ha_types[] = {
	{ ARPHRD_NETLINK,    "Netlink" },
	{ 0, NULL }
};

static dissector_handle_t netlink_handle;

static header_field_info *hfi_netlink = NULL;

#define NETLINK_HFI_INIT HFI_INIT(proto_netlink)

static header_field_info hfi_netlink_hatype NETLINK_HFI_INIT =
	{ "Link-layer address type", "netlink.hatype", FT_UINT16, BASE_DEC,
		VALS(ha_types), 0x0, NULL, HFILL };

/* Linux netlink protocol type */
static header_field_info hfi_netlink_family NETLINK_HFI_INIT =
	{ "Family", "netlink.family", FT_UINT16, BASE_HEX | BASE_EXT_STRING,
		&netlink_family_vals_ext, 0x00, NULL, HFILL };

static header_field_info hfi_netlink_hdr_len NETLINK_HFI_INIT =
	{ "Length", "netlink.hdr_len", FT_UINT32, BASE_DEC,
		NULL, 0x00, "Length of message including header", HFILL };

static header_field_info hfi_netlink_hdr_type NETLINK_HFI_INIT =
	{ "Message type", "netlink.hdr_type", FT_UINT16, BASE_HEX,
		VALS(type_vals), 0x00, "Type of message content", HFILL };

static header_field_info hfi_netlink_hdr_flags NETLINK_HFI_INIT =
	{ "Flags", "netlink.hdr_flags", FT_UINT16, BASE_HEX,
		NULL, 0x00, "Additional flags", HFILL };

static header_field_info hfi_netlink_hdr_flag_dumpfiltered NETLINK_HFI_INIT =
	{ "Dump filtered", "netlink.hdr_flags.dump_filtered", FT_UINT16, BASE_DEC,
		NULL, WS_NLM_F_DUMP_FILTERED, "Dump was filtered as requested", HFILL };

static header_field_info hfi_netlink_hdr_flag_dumpintr NETLINK_HFI_INIT =
	{ "Dump inconsistent", "netlink.hdr_flags.dump_intr", FT_UINT16, BASE_DEC,
		NULL, WS_NLM_F_DUMP_INTR, "Dump was inconsistent due to sequence change", HFILL };

static header_field_info hfi_netlink_hdr_flag_echo NETLINK_HFI_INIT =
	{ "Echo", "netlink.hdr_flags.echo", FT_UINT16, BASE_DEC,
		NULL, WS_NLM_F_ECHO, "Echo this request", HFILL };

static header_field_info hfi_netlink_hdr_flag_ack NETLINK_HFI_INIT =
	{ "Ack", "netlink.hdr_flags.ack", FT_UINT16, BASE_DEC,
		NULL, WS_NLM_F_ACK, "Asking for an ack", HFILL };

static header_field_info hfi_netlink_hdr_flag_multi NETLINK_HFI_INIT =
	{ "Multipart message", "netlink.hdr_flags.multi", FT_UINT16, BASE_DEC,
		NULL, WS_NLM_F_MULTI, "Part of multi-part message terminated by NLMSG_DONE", HFILL };

static header_field_info hfi_netlink_hdr_flag_request NETLINK_HFI_INIT =
	{ "Request", "netlink.hdr_flags.request", FT_UINT16, BASE_DEC,
		NULL, WS_NLM_F_REQUEST, "It is a request message", HFILL };

static header_field_info hfi_netlink_hdr_flag_root NETLINK_HFI_INIT =
	{ "Specify tree root", "netlink.hdr_flags.root", FT_UINT16, BASE_DEC,
		NULL, WS_NLM_F_ROOT, "Return the complete table instead of a single entry", HFILL };

static header_field_info hfi_netlink_hdr_flag_match NETLINK_HFI_INIT =
	{ "Return all matching", "netlink.hdr_flags.match", FT_UINT16, BASE_DEC,
		NULL, WS_NLM_F_MATCH, "Return all entries matching criteria in request", HFILL };

static header_field_info hfi_netlink_hdr_flag_atomic NETLINK_HFI_INIT =
	{ "Atomic", "netlink.hdr_flags.atomic", FT_UINT16, BASE_DEC,
		NULL, WS_NLM_F_ATOMIC, "Return an atomic snapshot of the table", HFILL };

static header_field_info hfi_netlink_hdr_flag_replace NETLINK_HFI_INIT =
	{ "Replace", "netlink.hdr_flags.replace", FT_UINT16, BASE_DEC,
		NULL, WS_NLM_F_REPLACE, "Replace existing objects", HFILL };

static header_field_info hfi_netlink_hdr_flag_excl NETLINK_HFI_INIT =
	{ "Excl", "netlink.hdr_flags.excl", FT_UINT16, BASE_DEC,
		NULL, WS_NLM_F_EXCL, "Do not replace existing objects", HFILL };

static header_field_info hfi_netlink_hdr_flag_create NETLINK_HFI_INIT =
	{ "Create", "netlink.hdr_flags.create", FT_UINT16, BASE_DEC,
		NULL, WS_NLM_F_CREATE, "Create objects if it does not already exist", HFILL };

static header_field_info hfi_netlink_hdr_flag_append NETLINK_HFI_INIT =
	{ "Append", "netlink.hdr_flags.append", FT_UINT16, BASE_DEC,
		NULL, WS_NLM_F_APPEND, "Add to end of object list", HFILL };

static header_field_info hfi_netlink_hdr_seq NETLINK_HFI_INIT =
	{ "Sequence", "netlink.hdr_seq", FT_UINT32, BASE_DEC,
		NULL, 0x00, "Sequence number", HFILL };

static header_field_info hfi_netlink_hdr_pid NETLINK_HFI_INIT =
	{ "Port ID", "netlink.hdr_pid", FT_UINT32, BASE_DEC,
		NULL, 0x00, "Sender port ID", HFILL };

static header_field_info hfi_netlink_attr_type NETLINK_HFI_INIT =
	{ "Type", "netlink.attr_type", FT_UINT16, BASE_HEX,
		NULL, 0x0000, "Netlink Attribute type", HFILL };

static header_field_info hfi_netlink_attr_type_nested NETLINK_HFI_INIT =
	{ "Nested", "netlink.attr_type.nested", FT_UINT16, BASE_DEC,
		NULL, NLA_F_NESTED, "Carries nested attributes", HFILL };

static header_field_info hfi_netlink_attr_type_net_byteorder NETLINK_HFI_INIT =
	{ "Network byte order", "netlink.attr_type.net_byteorder", FT_UINT16, BASE_DEC,
		NULL, NLA_F_NET_BYTEORDER, "Payload stored in network byte order", HFILL };

static header_field_info hfi_netlink_attr_len NETLINK_HFI_INIT =
	{ "Len", "netlink.attr_len", FT_UINT16, BASE_DEC,
		NULL, 0x00, NULL, HFILL };

/* TODO add a value_string for errno. */
static header_field_info hfi_netlink_error NETLINK_HFI_INIT =
	{ "Error code", "netlink.error", FT_INT32, BASE_DEC,
		NULL, 0x00, "Negative errno or 0 for acknowledgements", HFILL };

static gint ett_netlink_cooked = -1;
static gint ett_netlink_msghdr = -1;
static gint ett_netlink_msg = -1;
static gint ett_netlink_hdr_flags = -1;
static gint ett_netlink_attr_type = -1;

static dissector_table_t netlink_dissector_table;


static const int *netlink_header_get_flags[] = {
	&hfi_netlink_hdr_flag_request.id,
	&hfi_netlink_hdr_flag_multi.id,
	&hfi_netlink_hdr_flag_ack.id,
	&hfi_netlink_hdr_flag_echo.id,
	&hfi_netlink_hdr_flag_dumpintr.id,
	&hfi_netlink_hdr_flag_dumpfiltered.id,

	&hfi_netlink_hdr_flag_root.id,
	&hfi_netlink_hdr_flag_match.id,
	&hfi_netlink_hdr_flag_atomic.id,
	NULL
};

static const int *netlink_header_new_flags[] = {
	&hfi_netlink_hdr_flag_request.id,
	&hfi_netlink_hdr_flag_multi.id,
	&hfi_netlink_hdr_flag_ack.id,
	&hfi_netlink_hdr_flag_echo.id,
	&hfi_netlink_hdr_flag_dumpintr.id,
	&hfi_netlink_hdr_flag_dumpfiltered.id,

	&hfi_netlink_hdr_flag_replace.id,
	&hfi_netlink_hdr_flag_excl.id,
	&hfi_netlink_hdr_flag_create.id,
	&hfi_netlink_hdr_flag_append.id,
	NULL
};

static const int *netlink_header_standard_flags[] = {
	&hfi_netlink_hdr_flag_request.id,
	&hfi_netlink_hdr_flag_multi.id,
	&hfi_netlink_hdr_flag_ack.id,
	&hfi_netlink_hdr_flag_echo.id,
	&hfi_netlink_hdr_flag_dumpintr.id,
	&hfi_netlink_hdr_flag_dumpfiltered.id,
	NULL
};


int
dissect_netlink_attributes(tvbuff_t *tvb, header_field_info *hfi_type, int ett, void *data, struct packet_netlink_data *nl_data, proto_tree *tree, int offset, int length, netlink_attributes_cb_t cb)
{
	int encoding;
	int padding = (4 - offset) & 3;

	DISSECTOR_ASSERT(nl_data);

	encoding = nl_data->encoding;

	/* align to 4 */
	offset += padding;
	if (length == -1) {
		length = tvb_captured_length_remaining(tvb, offset);
	} else {
		length -= padding;
	}

	while (length >= 4) {
		guint16 rta_len, rta_type, type;

		proto_item *ti, *type_item;
		proto_tree *attr_tree, *type_tree;

		rta_len = tvb_get_guint16(tvb, offset, encoding);
		if (rta_len < 4) {
			/* XXX invalid expert */
			break;
		}

		/* XXX expert info when rta_len < length? */
		rta_len = MIN(rta_len, length);

		attr_tree = proto_tree_add_subtree(tree, tvb, offset, rta_len, ett, &ti, "Attribute");

		proto_tree_add_item(attr_tree, &hfi_netlink_attr_len, tvb, offset, 2, encoding);
		offset += 2;

		rta_type = tvb_get_guint16(tvb, offset, encoding);
		type = rta_type & NLA_TYPE_MASK;
		type_item = proto_tree_add_item(attr_tree, &hfi_netlink_attr_type, tvb, offset, 2, encoding);
		type_tree = proto_item_add_subtree(type_item, ett_netlink_attr_type);
		proto_tree_add_item(type_tree, &hfi_netlink_attr_type_nested, tvb, offset, 2, encoding);
		proto_tree_add_item(type_tree, &hfi_netlink_attr_type_net_byteorder, tvb, offset, 2, encoding);
		proto_tree_add_item(type_tree, hfi_type, tvb, offset, 2, encoding);
		offset += 2;

		if (rta_type & NLA_F_NESTED)
			proto_item_append_text(type_item, ", Nested");

		if (hfi_type->strings) {
			/* XXX, export hf_try_val_to_str */
			const char *rta_str = try_val_to_str(type, (const value_string *) hfi_type->strings);

			if (rta_str) {
				proto_item_append_text(type_item, ", %s (%d)", rta_str, type);
				proto_item_append_text(ti, ": %s", rta_str);
			}
		}

		if (!cb(tvb, data, attr_tree, rta_type, offset, rta_len - 4)) {
			/* not handled */
		}

		/* Assume offset already aligned, next offset is rta_len plus alignment. */
		rta_len = MIN((rta_len + 3) & ~3, length);
		offset += rta_len - 4;  /* Header was already skipped */
		length -= rta_len;
	}

	return offset;
}

static int
dissect_netlink_hdr(tvbuff_t *tvb, proto_tree *tree, int offset, int encoding, guint16 *type, guint32 *port_id)
{
	guint16 hdr_flags;
	guint16 hdr_type;

	proto_tree *fh_hdr;
	proto_item *pi_type;

	fh_hdr = proto_tree_add_subtree(tree, tvb, offset, 16, ett_netlink_msghdr, NULL, "Header");

	proto_tree_add_item(fh_hdr, &hfi_netlink_hdr_len, tvb, offset, 4, encoding);
	offset += 4;

	pi_type = proto_tree_add_item(fh_hdr, &hfi_netlink_hdr_type, tvb, offset, 2, encoding);
	hdr_type = tvb_get_guint16(tvb, offset, encoding);
	if (hdr_type >= WS_NLMSG_MIN_TYPE) {
		proto_item_set_text(pi_type, "Message type: Protocol-specific (0x%04x)", hdr_type);
	}
	if (type) {
		*type = hdr_type;
	}
	offset += 2;

	hdr_flags = tvb_get_guint16(tvb, offset, encoding);
	if ((hdr_flags & WS_NLM_F_REQUEST) && (hdr_flags & 0x0f00)) {
		/* XXX detect based on the protocol family and message type
		 * whether this is a GET, NEW or regular request. */
		proto_tree_add_bitmask(fh_hdr, tvb, offset, hfi_netlink_hdr_flags.id,
			ett_netlink_hdr_flags, netlink_header_get_flags, encoding);
		proto_tree_add_bitmask(fh_hdr, tvb, offset, hfi_netlink_hdr_flags.id,
			ett_netlink_hdr_flags, netlink_header_new_flags, encoding);
	} else {
		proto_tree_add_bitmask(fh_hdr, tvb, offset, hfi_netlink_hdr_flags.id,
			ett_netlink_hdr_flags, netlink_header_standard_flags, encoding);
	}

	offset += 2;

	proto_tree_add_item(fh_hdr, &hfi_netlink_hdr_seq, tvb, offset, 4, encoding);
	offset += 4;

	proto_tree_add_item_ret_uint(fh_hdr, hfi_netlink_hdr_pid.id, tvb, offset, 4, encoding, port_id);
	offset += 4;

	return offset;
}

static void
dissect_netlink_error(tvbuff_t *tvb, proto_tree *tree, int offset, int encoding)
{
	/*
	 * XXX - this should make sure we don't run past the end of the
	 * message.
	 */

	/*
	 * Assume sizeof(int) == 4; RFC 3549 doesn't say "32 bits", it
	 * says "integer (typically 32 bits)".
	 */
	proto_tree_add_item(tree, &hfi_netlink_error, tvb, offset, 4, encoding);
	offset += 4;

	dissect_netlink_hdr(tvb, tree, offset, encoding, NULL, NULL);
}

static int
dissect_netlink(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *_data _U_)
{
	guint16     protocol, hatype;
	proto_item *ti;
	tvbuff_t   *next_tvb;
	proto_tree *fh_tree;

	int offset;
	int encoding;
	guint len_rem, len_le, len_be;

	hatype = tvb_get_ntohs(tvb, 2);
	if (hatype != ARPHRD_NETLINK)
		return 0;

	col_set_str(pinfo->cinfo, COL_PROTOCOL, "Netlink");
	col_clear(pinfo->cinfo, COL_INFO);

	ti = proto_tree_add_protocol_format(tree, hfi_netlink->id, tvb, 0,
			SLL_HEADER_SIZE, "Linux netlink (cooked header)");
	fh_tree = proto_item_add_subtree(ti, ett_netlink_cooked);

	/* Unused 2B */
	offset = 2;

	proto_tree_add_item(fh_tree, &hfi_netlink_hatype, tvb, offset, 2, ENC_BIG_ENDIAN);
	offset += 2;

	/* Unused 10B */
	offset += 10;

	protocol = tvb_get_ntohs(tvb, offset);
	proto_tree_add_item(fh_tree, &hfi_netlink_family, tvb, offset, 2, ENC_BIG_ENDIAN);
	offset += 2;

	/* DISSECTOR_ASSERT(offset == 16); */

	/*
	 * We are unable to detect the endianness, we have to guess. Compare
	 * the size of the inner package with the size of the outer package,
	 * take the endianness in which the inner package length is closer to
	 * the size of the outer package. Normally we have packages with less
	 * than 10KB here so the sizes are very huge in the wrong endianness.
	 */
	len_rem = tvb_reported_length_remaining(tvb, offset);
	len_le = tvb_get_letohl(tvb, offset);
	len_be = tvb_get_ntohl(tvb, offset);
	#define abs_diff(a, b) ((a) > (b) ? (a) - (b) : (b) - (a))
	if (abs_diff(len_be, len_rem) < abs_diff(len_le, len_rem)) {
		encoding = ENC_BIG_ENDIAN;
	} else {
		encoding = ENC_LITTLE_ENDIAN;
	}

	while (tvb_reported_length_remaining(tvb, offset) >= 16) {
		struct packet_netlink_data data;

		int pkt_end_offset;
		guint32 pkt_len;
		guint32 port_id;

		proto_tree *fh_msg;


		pkt_len = tvb_get_guint32(tvb, offset, encoding);

		pkt_end_offset = offset + pkt_len;

		fh_msg = proto_tree_add_subtree(tree, tvb, offset, pkt_len, ett_netlink_msg, NULL, "Netlink message");

		if (pkt_len < 16) {
			/*
			 * This field includes the length of the 16-byte header,
			 * so its value is invalid.  Add it, report an error,
			 * and stop trying to dissect.
			 */
			proto_tree *fh_hdr;

			fh_hdr = proto_tree_add_subtree(tree, tvb, offset, 4, ett_netlink_msghdr, NULL, "Header");

			proto_tree_add_item(fh_hdr, &hfi_netlink_hdr_len, tvb, offset, 4, encoding);
			/* XXX invalid expert */
			break;
		}

		offset = dissect_netlink_hdr(tvb, fh_msg, offset, encoding, &data.type, &port_id);

		/* XXX */
		if (port_id == 0x00)
			pinfo->p2p_dir = P2P_DIR_SENT; /* userspace -> kernel */
		else
			pinfo->p2p_dir = P2P_DIR_RECV; /* userspace or kernel -> userspace */

		if (data.type == WS_NLMSG_ERROR) {
			dissect_netlink_error(tvb, fh_msg, offset, encoding);
		} else if (pkt_len > 16) {
			data.magic = PACKET_NETLINK_MAGIC;
			data.encoding = encoding;

			next_tvb = tvb_new_subset_length(tvb, offset, pkt_len-16);

			if (!dissector_try_uint_new(netlink_dissector_table, protocol, next_tvb, pinfo, fh_msg, TRUE, &data))
				call_data_dissector(next_tvb, pinfo, fh_msg);

		}

		offset = pkt_end_offset;
	}

	return offset;
}

void
proto_register_netlink(void)
{
#ifndef HAVE_HFI_SECTION_INIT
	static header_field_info *hfi[] = {
	/* Cooked header */
		&hfi_netlink_hatype,
		&hfi_netlink_family,

	/* Netlink message header */
		&hfi_netlink_hdr_len,
		&hfi_netlink_hdr_type,
		&hfi_netlink_hdr_flags,
		&hfi_netlink_hdr_flag_request,
		&hfi_netlink_hdr_flag_multi,
		&hfi_netlink_hdr_flag_ack,
		&hfi_netlink_hdr_flag_echo,
		&hfi_netlink_hdr_flag_dumpintr,
		&hfi_netlink_hdr_flag_dumpfiltered,

		&hfi_netlink_hdr_flag_root,
		&hfi_netlink_hdr_flag_match,
		&hfi_netlink_hdr_flag_atomic,

		&hfi_netlink_hdr_flag_replace,
		&hfi_netlink_hdr_flag_excl,
		&hfi_netlink_hdr_flag_create,
		&hfi_netlink_hdr_flag_append,

		&hfi_netlink_hdr_seq,
		&hfi_netlink_hdr_pid,

	/* Netlink message attribute */
		&hfi_netlink_attr_len,
		&hfi_netlink_attr_type,
		&hfi_netlink_attr_type_nested,
		&hfi_netlink_attr_type_net_byteorder,

	/* Netlink message payloads */
		&hfi_netlink_error,
	};
#endif

	static gint *ett[] = {
		&ett_netlink_cooked,
		&ett_netlink_msghdr,
		&ett_netlink_msg,
		&ett_netlink_hdr_flags,
		&ett_netlink_attr_type,
	};

	int proto_netlink;

	proto_netlink = proto_register_protocol("Linux netlink protocol",  "NETLINK", "netlink" );
	hfi_netlink = proto_registrar_get_nth(proto_netlink);

	proto_register_fields(proto_netlink, hfi, array_length(hfi));
	proto_register_subtree_array(ett, array_length(ett));

	netlink_handle = create_dissector_handle(dissect_netlink, proto_netlink);

	netlink_dissector_table = register_dissector_table(
		"netlink.protocol",
		"Linux netlink protocol type",
		proto_netlink, FT_UINT16,
		BASE_HEX
	);
	register_dissector("netlink", dissect_netlink, proto_netlink);
}

void
proto_reg_handoff_netlink(void)
{
	dissector_add_uint("wtap_encap", WTAP_ENCAP_NETLINK, netlink_handle);
}

/*
 * Editor modelines  -  http://www.wireshark.org/tools/modelines.html
 *
 * Local variables:
 * c-basic-offset: 8
 * tab-width: 8
 * indent-tabs-mode: t
 * End:
 *
 * vi: set shiftwidth=8 tabstop=8 noexpandtab:
 * :indentSize=8:tabSize=8:noTabs=false:
 */