// SPDX-License-Identifier: GPL-2.0-only
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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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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/kernel.h>
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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/ipv6.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/xt_LOG.h>
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#include <net/netfilter/nf_log.h>
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static const 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 = LOGLEVEL_NOTICE,
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.logflags = NF_LOG_DEFAULT_MASK,
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},
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},
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};
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/* One level of recursion won't kill us */
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static void dump_ipv4_packet(struct net *net, struct nf_log_buf *m,
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const struct nf_loginfo *info,
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const struct sk_buff *skb, 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_DEFAULT_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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nf_log_buf_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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nf_log_buf_add(m, "SRC=%pI4 DST=%pI4 ", &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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nf_log_buf_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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nf_log_buf_add(m, "CE ");
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if (ntohs(ih->frag_off) & IP_DF)
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nf_log_buf_add(m, "DF ");
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if (ntohs(ih->frag_off) & IP_MF)
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nf_log_buf_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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nf_log_buf_add(m, "FRAG:%u ", ntohs(ih->frag_off) & IP_OFFSET);
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if ((logflags & NF_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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nf_log_buf_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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nf_log_buf_add(m, "OPT (");
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for (i = 0; i < optsize; i++)
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nf_log_buf_add(m, "%02X", op[i]);
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nf_log_buf_add(m, ") ");
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}
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switch (ih->protocol) {
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case IPPROTO_TCP:
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if (nf_log_dump_tcp_header(m, skb, ih->protocol,
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ntohs(ih->frag_off) & IP_OFFSET,
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iphoff+ih->ihl*4, logflags))
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return;
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break;
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case IPPROTO_UDP:
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case IPPROTO_UDPLITE:
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if (nf_log_dump_udp_header(m, skb, ih->protocol,
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ntohs(ih->frag_off) & IP_OFFSET,
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iphoff+ih->ihl*4))
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return;
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break;
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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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nf_log_buf_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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nf_log_buf_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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nf_log_buf_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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nf_log_buf_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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nf_log_buf_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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nf_log_buf_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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nf_log_buf_add(m, "GATEWAY=%pI4 ", &ich->un.gateway);
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fallthrough;
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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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nf_log_buf_add(m, "[");
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dump_ipv4_packet(net, m, info, skb,
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iphoff + ih->ihl*4+sizeof(_icmph));
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nf_log_buf_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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nf_log_buf_add(m, "MTU=%u ",
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ntohs(ich->un.frag.mtu));
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}
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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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nf_log_buf_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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nf_log_buf_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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nf_log_buf_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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nf_log_buf_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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nf_log_buf_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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nf_log_buf_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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nf_log_buf_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 & NF_LOG_UID) && !iphoff)
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nf_log_dump_sk_uid_gid(net, m, skb->sk);
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/* Max length: 16 "MARK=0xFFFFFFFF " */
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if (!iphoff && skb->mark)
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nf_log_buf_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_ipv4_mac_header(struct nf_log_buf *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 & NF_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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nf_log_buf_add(m, "MACSRC=%pM MACDST=%pM ",
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eth_hdr(skb)->h_source, eth_hdr(skb)->h_dest);
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nf_log_dump_vlan(m, skb);
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nf_log_buf_add(m, "MACPROTO=%04x ",
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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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nf_log_buf_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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nf_log_buf_add(m, "%02x", *p++);
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for (i = 1; i < dev->hard_header_len; i++, p++)
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nf_log_buf_add(m, ":%02x", *p);
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}
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nf_log_buf_add(m, " ");
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}
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static void nf_log_ip_packet(struct net *net, u_int8_t pf,
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unsigned int hooknum, 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 nf_log_buf *m;
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/* FIXME: Disabled from containers until syslog ns is supported */
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if (!net_eq(net, &init_net) && !sysctl_nf_log_all_netns)
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return;
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m = nf_log_buf_open();
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if (!loginfo)
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loginfo = &default_loginfo;
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nf_log_dump_packet_common(m, pf, hooknum, skb, in,
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out, loginfo, prefix);
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if (in != NULL)
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dump_ipv4_mac_header(m, loginfo, skb);
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dump_ipv4_packet(net, m, loginfo, skb, 0);
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nf_log_buf_close(m);
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}
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static struct nf_logger nf_ip_logger __read_mostly = {
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.name = "nf_log_ipv4",
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.type = NF_LOG_TYPE_LOG,
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.logfn = nf_log_ip_packet,
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.me = THIS_MODULE,
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};
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static int __net_init nf_log_ipv4_net_init(struct net *net)
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{
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return nf_log_set(net, NFPROTO_IPV4, &nf_ip_logger);
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}
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static void __net_exit nf_log_ipv4_net_exit(struct net *net)
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{
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nf_log_unset(net, &nf_ip_logger);
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}
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static struct pernet_operations nf_log_ipv4_net_ops = {
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.init = nf_log_ipv4_net_init,
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.exit = nf_log_ipv4_net_exit,
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};
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static int __init nf_log_ipv4_init(void)
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{
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int ret;
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ret = register_pernet_subsys(&nf_log_ipv4_net_ops);
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if (ret < 0)
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return ret;
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ret = nf_log_register(NFPROTO_IPV4, &nf_ip_logger);
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if (ret < 0) {
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pr_err("failed to register logger\n");
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goto err1;
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}
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return 0;
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err1:
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unregister_pernet_subsys(&nf_log_ipv4_net_ops);
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return ret;
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}
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static void __exit nf_log_ipv4_exit(void)
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{
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unregister_pernet_subsys(&nf_log_ipv4_net_ops);
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nf_log_unregister(&nf_ip_logger);
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}
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module_init(nf_log_ipv4_init);
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module_exit(nf_log_ipv4_exit);
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MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
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MODULE_DESCRIPTION("Netfilter IPv4 packet logging");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS_NF_LOGGER(AF_INET, 0);
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