![Jan Engelhardt](/assets/img/avatar_default.png)
I am observing consistent behavior even with bridges, so let's unlock this. xt_mac is already usable in FORWARD, too. Section 9 of http://ebtables.sourceforge.net/br_fw_ia/br_fw_ia.html#section9 says the MAC source address is changed, but my observation does not match that claim -- the MAC header is retained. Signed-off-by: Jan Engelhardt <jengelh@medozas.de> [Patrick; code inspection seems to confirm this] Signed-off-by: Patrick McHardy <kaber@trash.net>
517 lines
13 KiB
C
517 lines
13 KiB
C
/*
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* This is a module which is used for logging packets.
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*/
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/* (C) 1999-2001 Paul `Rusty' Russell
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* (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
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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 version 2 as
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* published by the Free Software Foundation.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/spinlock.h>
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#include <linux/skbuff.h>
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#include <linux/if_arp.h>
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#include <linux/ip.h>
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#include <net/icmp.h>
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#include <net/udp.h>
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#include <net/tcp.h>
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#include <net/route.h>
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#include <linux/netfilter.h>
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#include <linux/netfilter/x_tables.h>
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#include <linux/netfilter_ipv4/ipt_LOG.h>
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#include <net/netfilter/nf_log.h>
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#include <net/netfilter/xt_log.h>
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
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MODULE_DESCRIPTION("Xtables: IPv4 packet logging to syslog");
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/* One level of recursion won't kill us */
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static void dump_packet(struct sbuff *m,
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const struct nf_loginfo *info,
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const struct sk_buff *skb,
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unsigned int iphoff)
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{
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struct iphdr _iph;
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const struct iphdr *ih;
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unsigned int logflags;
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if (info->type == NF_LOG_TYPE_LOG)
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logflags = info->u.log.logflags;
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else
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logflags = NF_LOG_MASK;
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ih = skb_header_pointer(skb, iphoff, sizeof(_iph), &_iph);
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if (ih == NULL) {
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sb_add(m, "TRUNCATED");
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return;
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}
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/* Important fields:
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* TOS, len, DF/MF, fragment offset, TTL, src, dst, options. */
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/* Max length: 40 "SRC=255.255.255.255 DST=255.255.255.255 " */
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sb_add(m, "SRC=%pI4 DST=%pI4 ",
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&ih->saddr, &ih->daddr);
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/* Max length: 46 "LEN=65535 TOS=0xFF PREC=0xFF TTL=255 ID=65535 " */
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sb_add(m, "LEN=%u TOS=0x%02X PREC=0x%02X TTL=%u ID=%u ",
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ntohs(ih->tot_len), ih->tos & IPTOS_TOS_MASK,
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ih->tos & IPTOS_PREC_MASK, ih->ttl, ntohs(ih->id));
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/* Max length: 6 "CE DF MF " */
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if (ntohs(ih->frag_off) & IP_CE)
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sb_add(m, "CE ");
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if (ntohs(ih->frag_off) & IP_DF)
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sb_add(m, "DF ");
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if (ntohs(ih->frag_off) & IP_MF)
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sb_add(m, "MF ");
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/* Max length: 11 "FRAG:65535 " */
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if (ntohs(ih->frag_off) & IP_OFFSET)
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sb_add(m, "FRAG:%u ", ntohs(ih->frag_off) & IP_OFFSET);
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if ((logflags & IPT_LOG_IPOPT) &&
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ih->ihl * 4 > sizeof(struct iphdr)) {
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const unsigned char *op;
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unsigned char _opt[4 * 15 - sizeof(struct iphdr)];
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unsigned int i, optsize;
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optsize = ih->ihl * 4 - sizeof(struct iphdr);
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op = skb_header_pointer(skb, iphoff+sizeof(_iph),
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optsize, _opt);
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if (op == NULL) {
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sb_add(m, "TRUNCATED");
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return;
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}
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/* Max length: 127 "OPT (" 15*4*2chars ") " */
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sb_add(m, "OPT (");
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for (i = 0; i < optsize; i++)
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sb_add(m, "%02X", op[i]);
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sb_add(m, ") ");
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}
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switch (ih->protocol) {
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case IPPROTO_TCP: {
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struct tcphdr _tcph;
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const struct tcphdr *th;
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/* Max length: 10 "PROTO=TCP " */
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sb_add(m, "PROTO=TCP ");
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if (ntohs(ih->frag_off) & IP_OFFSET)
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break;
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/* Max length: 25 "INCOMPLETE [65535 bytes] " */
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th = skb_header_pointer(skb, iphoff + ih->ihl * 4,
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sizeof(_tcph), &_tcph);
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if (th == NULL) {
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sb_add(m, "INCOMPLETE [%u bytes] ",
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skb->len - iphoff - ih->ihl*4);
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break;
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}
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/* Max length: 20 "SPT=65535 DPT=65535 " */
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sb_add(m, "SPT=%u DPT=%u ",
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ntohs(th->source), ntohs(th->dest));
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/* Max length: 30 "SEQ=4294967295 ACK=4294967295 " */
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if (logflags & IPT_LOG_TCPSEQ)
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sb_add(m, "SEQ=%u ACK=%u ",
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ntohl(th->seq), ntohl(th->ack_seq));
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/* Max length: 13 "WINDOW=65535 " */
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sb_add(m, "WINDOW=%u ", ntohs(th->window));
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/* Max length: 9 "RES=0x3F " */
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sb_add(m, "RES=0x%02x ", (u8)(ntohl(tcp_flag_word(th) & TCP_RESERVED_BITS) >> 22));
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/* Max length: 32 "CWR ECE URG ACK PSH RST SYN FIN " */
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if (th->cwr)
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sb_add(m, "CWR ");
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if (th->ece)
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sb_add(m, "ECE ");
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if (th->urg)
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sb_add(m, "URG ");
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if (th->ack)
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sb_add(m, "ACK ");
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if (th->psh)
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sb_add(m, "PSH ");
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if (th->rst)
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sb_add(m, "RST ");
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if (th->syn)
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sb_add(m, "SYN ");
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if (th->fin)
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sb_add(m, "FIN ");
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/* Max length: 11 "URGP=65535 " */
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sb_add(m, "URGP=%u ", ntohs(th->urg_ptr));
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if ((logflags & IPT_LOG_TCPOPT) &&
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th->doff * 4 > sizeof(struct tcphdr)) {
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unsigned char _opt[4 * 15 - sizeof(struct tcphdr)];
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const unsigned char *op;
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unsigned int i, optsize;
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optsize = th->doff * 4 - sizeof(struct tcphdr);
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op = skb_header_pointer(skb,
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iphoff+ih->ihl*4+sizeof(_tcph),
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optsize, _opt);
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if (op == NULL) {
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sb_add(m, "TRUNCATED");
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return;
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}
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/* Max length: 127 "OPT (" 15*4*2chars ") " */
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sb_add(m, "OPT (");
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for (i = 0; i < optsize; i++)
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sb_add(m, "%02X", op[i]);
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sb_add(m, ") ");
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}
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break;
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}
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case IPPROTO_UDP:
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case IPPROTO_UDPLITE: {
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struct udphdr _udph;
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const struct udphdr *uh;
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if (ih->protocol == IPPROTO_UDP)
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/* Max length: 10 "PROTO=UDP " */
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sb_add(m, "PROTO=UDP " );
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else /* Max length: 14 "PROTO=UDPLITE " */
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sb_add(m, "PROTO=UDPLITE ");
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if (ntohs(ih->frag_off) & IP_OFFSET)
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break;
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/* Max length: 25 "INCOMPLETE [65535 bytes] " */
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uh = skb_header_pointer(skb, iphoff+ih->ihl*4,
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sizeof(_udph), &_udph);
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if (uh == NULL) {
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sb_add(m, "INCOMPLETE [%u bytes] ",
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skb->len - iphoff - ih->ihl*4);
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break;
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}
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/* Max length: 20 "SPT=65535 DPT=65535 " */
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sb_add(m, "SPT=%u DPT=%u LEN=%u ",
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ntohs(uh->source), ntohs(uh->dest),
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ntohs(uh->len));
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break;
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}
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case IPPROTO_ICMP: {
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struct icmphdr _icmph;
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const struct icmphdr *ich;
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static const size_t required_len[NR_ICMP_TYPES+1]
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= { [ICMP_ECHOREPLY] = 4,
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[ICMP_DEST_UNREACH]
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= 8 + sizeof(struct iphdr),
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[ICMP_SOURCE_QUENCH]
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= 8 + sizeof(struct iphdr),
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[ICMP_REDIRECT]
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= 8 + sizeof(struct iphdr),
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[ICMP_ECHO] = 4,
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[ICMP_TIME_EXCEEDED]
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= 8 + sizeof(struct iphdr),
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[ICMP_PARAMETERPROB]
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= 8 + sizeof(struct iphdr),
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[ICMP_TIMESTAMP] = 20,
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[ICMP_TIMESTAMPREPLY] = 20,
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[ICMP_ADDRESS] = 12,
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[ICMP_ADDRESSREPLY] = 12 };
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/* Max length: 11 "PROTO=ICMP " */
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sb_add(m, "PROTO=ICMP ");
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if (ntohs(ih->frag_off) & IP_OFFSET)
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break;
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/* Max length: 25 "INCOMPLETE [65535 bytes] " */
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ich = skb_header_pointer(skb, iphoff + ih->ihl * 4,
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sizeof(_icmph), &_icmph);
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if (ich == NULL) {
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sb_add(m, "INCOMPLETE [%u bytes] ",
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skb->len - iphoff - ih->ihl*4);
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break;
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}
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/* Max length: 18 "TYPE=255 CODE=255 " */
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sb_add(m, "TYPE=%u CODE=%u ", ich->type, ich->code);
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/* Max length: 25 "INCOMPLETE [65535 bytes] " */
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if (ich->type <= NR_ICMP_TYPES &&
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required_len[ich->type] &&
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skb->len-iphoff-ih->ihl*4 < required_len[ich->type]) {
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sb_add(m, "INCOMPLETE [%u bytes] ",
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skb->len - iphoff - ih->ihl*4);
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break;
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}
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switch (ich->type) {
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case ICMP_ECHOREPLY:
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case ICMP_ECHO:
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/* Max length: 19 "ID=65535 SEQ=65535 " */
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sb_add(m, "ID=%u SEQ=%u ",
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ntohs(ich->un.echo.id),
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ntohs(ich->un.echo.sequence));
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break;
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case ICMP_PARAMETERPROB:
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/* Max length: 14 "PARAMETER=255 " */
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sb_add(m, "PARAMETER=%u ",
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ntohl(ich->un.gateway) >> 24);
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break;
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case ICMP_REDIRECT:
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/* Max length: 24 "GATEWAY=255.255.255.255 " */
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sb_add(m, "GATEWAY=%pI4 ", &ich->un.gateway);
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/* Fall through */
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case ICMP_DEST_UNREACH:
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case ICMP_SOURCE_QUENCH:
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case ICMP_TIME_EXCEEDED:
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/* Max length: 3+maxlen */
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if (!iphoff) { /* Only recurse once. */
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sb_add(m, "[");
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dump_packet(m, info, skb,
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iphoff + ih->ihl*4+sizeof(_icmph));
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sb_add(m, "] ");
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}
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/* Max length: 10 "MTU=65535 " */
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if (ich->type == ICMP_DEST_UNREACH &&
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ich->code == ICMP_FRAG_NEEDED)
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sb_add(m, "MTU=%u ", ntohs(ich->un.frag.mtu));
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}
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break;
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}
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/* Max Length */
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case IPPROTO_AH: {
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struct ip_auth_hdr _ahdr;
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const struct ip_auth_hdr *ah;
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if (ntohs(ih->frag_off) & IP_OFFSET)
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break;
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/* Max length: 9 "PROTO=AH " */
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sb_add(m, "PROTO=AH ");
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/* Max length: 25 "INCOMPLETE [65535 bytes] " */
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ah = skb_header_pointer(skb, iphoff+ih->ihl*4,
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sizeof(_ahdr), &_ahdr);
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if (ah == NULL) {
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sb_add(m, "INCOMPLETE [%u bytes] ",
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skb->len - iphoff - ih->ihl*4);
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break;
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}
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/* Length: 15 "SPI=0xF1234567 " */
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sb_add(m, "SPI=0x%x ", ntohl(ah->spi));
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break;
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}
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case IPPROTO_ESP: {
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struct ip_esp_hdr _esph;
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const struct ip_esp_hdr *eh;
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/* Max length: 10 "PROTO=ESP " */
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sb_add(m, "PROTO=ESP ");
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if (ntohs(ih->frag_off) & IP_OFFSET)
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break;
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/* Max length: 25 "INCOMPLETE [65535 bytes] " */
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eh = skb_header_pointer(skb, iphoff+ih->ihl*4,
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sizeof(_esph), &_esph);
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if (eh == NULL) {
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sb_add(m, "INCOMPLETE [%u bytes] ",
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skb->len - iphoff - ih->ihl*4);
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break;
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}
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/* Length: 15 "SPI=0xF1234567 " */
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sb_add(m, "SPI=0x%x ", ntohl(eh->spi));
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break;
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}
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/* Max length: 10 "PROTO 255 " */
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default:
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sb_add(m, "PROTO=%u ", ih->protocol);
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}
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/* Max length: 15 "UID=4294967295 " */
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if ((logflags & IPT_LOG_UID) && !iphoff && skb->sk) {
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read_lock_bh(&skb->sk->sk_callback_lock);
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if (skb->sk->sk_socket && skb->sk->sk_socket->file)
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sb_add(m, "UID=%u GID=%u ",
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skb->sk->sk_socket->file->f_cred->fsuid,
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skb->sk->sk_socket->file->f_cred->fsgid);
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read_unlock_bh(&skb->sk->sk_callback_lock);
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}
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/* Max length: 16 "MARK=0xFFFFFFFF " */
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if (!iphoff && skb->mark)
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sb_add(m, "MARK=0x%x ", skb->mark);
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/* Proto Max log string length */
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/* IP: 40+46+6+11+127 = 230 */
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/* TCP: 10+max(25,20+30+13+9+32+11+127) = 252 */
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/* UDP: 10+max(25,20) = 35 */
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/* UDPLITE: 14+max(25,20) = 39 */
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/* ICMP: 11+max(25, 18+25+max(19,14,24+3+n+10,3+n+10)) = 91+n */
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/* ESP: 10+max(25)+15 = 50 */
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/* AH: 9+max(25)+15 = 49 */
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/* unknown: 10 */
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/* (ICMP allows recursion one level deep) */
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/* maxlen = IP + ICMP + IP + max(TCP,UDP,ICMP,unknown) */
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/* maxlen = 230+ 91 + 230 + 252 = 803 */
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}
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static void dump_mac_header(struct sbuff *m,
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const struct nf_loginfo *info,
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const struct sk_buff *skb)
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{
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struct net_device *dev = skb->dev;
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unsigned int logflags = 0;
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if (info->type == NF_LOG_TYPE_LOG)
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logflags = info->u.log.logflags;
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if (!(logflags & IPT_LOG_MACDECODE))
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goto fallback;
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switch (dev->type) {
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case ARPHRD_ETHER:
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sb_add(m, "MACSRC=%pM MACDST=%pM MACPROTO=%04x ",
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eth_hdr(skb)->h_source, eth_hdr(skb)->h_dest,
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ntohs(eth_hdr(skb)->h_proto));
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return;
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default:
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break;
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}
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fallback:
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sb_add(m, "MAC=");
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if (dev->hard_header_len &&
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skb->mac_header != skb->network_header) {
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const unsigned char *p = skb_mac_header(skb);
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unsigned int i;
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sb_add(m, "%02x", *p++);
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for (i = 1; i < dev->hard_header_len; i++, p++)
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sb_add(m, ":%02x", *p);
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}
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sb_add(m, " ");
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}
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static struct nf_loginfo default_loginfo = {
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.type = NF_LOG_TYPE_LOG,
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.u = {
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.log = {
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.level = 5,
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.logflags = NF_LOG_MASK,
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},
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},
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};
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static void
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ipt_log_packet(u_int8_t pf,
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unsigned int hooknum,
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const struct sk_buff *skb,
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const struct net_device *in,
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const struct net_device *out,
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const struct nf_loginfo *loginfo,
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const char *prefix)
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{
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struct sbuff *m = sb_open();
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if (!loginfo)
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loginfo = &default_loginfo;
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sb_add(m, "<%d>%sIN=%s OUT=%s ", loginfo->u.log.level,
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prefix,
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in ? in->name : "",
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out ? out->name : "");
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#ifdef CONFIG_BRIDGE_NETFILTER
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if (skb->nf_bridge) {
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const struct net_device *physindev;
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const struct net_device *physoutdev;
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physindev = skb->nf_bridge->physindev;
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if (physindev && in != physindev)
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sb_add(m, "PHYSIN=%s ", physindev->name);
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physoutdev = skb->nf_bridge->physoutdev;
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if (physoutdev && out != physoutdev)
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sb_add(m, "PHYSOUT=%s ", physoutdev->name);
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}
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#endif
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if (in != NULL)
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dump_mac_header(m, loginfo, skb);
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dump_packet(m, loginfo, skb, 0);
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sb_close(m);
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}
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static unsigned int
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log_tg(struct sk_buff *skb, const struct xt_action_param *par)
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{
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const struct ipt_log_info *loginfo = par->targinfo;
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struct nf_loginfo li;
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li.type = NF_LOG_TYPE_LOG;
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li.u.log.level = loginfo->level;
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li.u.log.logflags = loginfo->logflags;
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ipt_log_packet(NFPROTO_IPV4, par->hooknum, skb, par->in, par->out, &li,
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loginfo->prefix);
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return XT_CONTINUE;
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|
}
|
|
|
|
static int log_tg_check(const struct xt_tgchk_param *par)
|
|
{
|
|
const struct ipt_log_info *loginfo = par->targinfo;
|
|
|
|
if (loginfo->level >= 8) {
|
|
pr_debug("level %u >= 8\n", loginfo->level);
|
|
return -EINVAL;
|
|
}
|
|
if (loginfo->prefix[sizeof(loginfo->prefix)-1] != '\0') {
|
|
pr_debug("prefix is not null-terminated\n");
|
|
return -EINVAL;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static struct xt_target log_tg_reg __read_mostly = {
|
|
.name = "LOG",
|
|
.family = NFPROTO_IPV4,
|
|
.target = log_tg,
|
|
.targetsize = sizeof(struct ipt_log_info),
|
|
.checkentry = log_tg_check,
|
|
.me = THIS_MODULE,
|
|
};
|
|
|
|
static struct nf_logger ipt_log_logger __read_mostly = {
|
|
.name = "ipt_LOG",
|
|
.logfn = &ipt_log_packet,
|
|
.me = THIS_MODULE,
|
|
};
|
|
|
|
static int __init log_tg_init(void)
|
|
{
|
|
int ret;
|
|
|
|
ret = xt_register_target(&log_tg_reg);
|
|
if (ret < 0)
|
|
return ret;
|
|
nf_log_register(NFPROTO_IPV4, &ipt_log_logger);
|
|
return 0;
|
|
}
|
|
|
|
static void __exit log_tg_exit(void)
|
|
{
|
|
nf_log_unregister(&ipt_log_logger);
|
|
xt_unregister_target(&log_tg_reg);
|
|
}
|
|
|
|
module_init(log_tg_init);
|
|
module_exit(log_tg_exit);
|