/* * This is a module which is used for logging packets. */ /* (C) 1999-2001 Paul `Rusty' Russell * (C) 2002-2004 Netfilter Core Team * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include #include #include #include #include #include #include #include #include #include #include #include MODULE_LICENSE("GPL"); MODULE_AUTHOR("Netfilter Core Team "); MODULE_DESCRIPTION("Xtables: IPv4 packet logging to syslog"); /* Use lock to serialize, so printks don't overlap */ static DEFINE_SPINLOCK(log_lock); /* One level of recursion won't kill us */ static void dump_packet(const struct nf_loginfo *info, const struct sk_buff *skb, unsigned int iphoff) { struct iphdr _iph; const struct iphdr *ih; unsigned int logflags; if (info->type == NF_LOG_TYPE_LOG) logflags = info->u.log.logflags; else logflags = NF_LOG_MASK; ih = skb_header_pointer(skb, iphoff, sizeof(_iph), &_iph); if (ih == NULL) { printk("TRUNCATED"); return; } /* Important fields: * TOS, len, DF/MF, fragment offset, TTL, src, dst, options. */ /* Max length: 40 "SRC=255.255.255.255 DST=255.255.255.255 " */ printk("SRC=%pI4 DST=%pI4 ", &ih->saddr, &ih->daddr); /* Max length: 46 "LEN=65535 TOS=0xFF PREC=0xFF TTL=255 ID=65535 " */ printk("LEN=%u TOS=0x%02X PREC=0x%02X TTL=%u ID=%u ", ntohs(ih->tot_len), ih->tos & IPTOS_TOS_MASK, ih->tos & IPTOS_PREC_MASK, ih->ttl, ntohs(ih->id)); /* Max length: 6 "CE DF MF " */ if (ntohs(ih->frag_off) & IP_CE) printk("CE "); if (ntohs(ih->frag_off) & IP_DF) printk("DF "); if (ntohs(ih->frag_off) & IP_MF) printk("MF "); /* Max length: 11 "FRAG:65535 " */ if (ntohs(ih->frag_off) & IP_OFFSET) printk("FRAG:%u ", ntohs(ih->frag_off) & IP_OFFSET); if ((logflags & IPT_LOG_IPOPT) && ih->ihl * 4 > sizeof(struct iphdr)) { const unsigned char *op; unsigned char _opt[4 * 15 - sizeof(struct iphdr)]; unsigned int i, optsize; optsize = ih->ihl * 4 - sizeof(struct iphdr); op = skb_header_pointer(skb, iphoff+sizeof(_iph), optsize, _opt); if (op == NULL) { printk("TRUNCATED"); return; } /* Max length: 127 "OPT (" 15*4*2chars ") " */ printk("OPT ("); for (i = 0; i < optsize; i++) printk("%02X", op[i]); printk(") "); } switch (ih->protocol) { case IPPROTO_TCP: { struct tcphdr _tcph; const struct tcphdr *th; /* Max length: 10 "PROTO=TCP " */ printk("PROTO=TCP "); if (ntohs(ih->frag_off) & IP_OFFSET) break; /* Max length: 25 "INCOMPLETE [65535 bytes] " */ th = skb_header_pointer(skb, iphoff + ih->ihl * 4, sizeof(_tcph), &_tcph); if (th == NULL) { printk("INCOMPLETE [%u bytes] ", skb->len - iphoff - ih->ihl*4); break; } /* Max length: 20 "SPT=65535 DPT=65535 " */ printk("SPT=%u DPT=%u ", ntohs(th->source), ntohs(th->dest)); /* Max length: 30 "SEQ=4294967295 ACK=4294967295 " */ if (logflags & IPT_LOG_TCPSEQ) printk("SEQ=%u ACK=%u ", ntohl(th->seq), ntohl(th->ack_seq)); /* Max length: 13 "WINDOW=65535 " */ printk("WINDOW=%u ", ntohs(th->window)); /* Max length: 9 "RES=0x3F " */ printk("RES=0x%02x ", (u8)(ntohl(tcp_flag_word(th) & TCP_RESERVED_BITS) >> 22)); /* Max length: 32 "CWR ECE URG ACK PSH RST SYN FIN " */ if (th->cwr) printk("CWR "); if (th->ece) printk("ECE "); if (th->urg) printk("URG "); if (th->ack) printk("ACK "); if (th->psh) printk("PSH "); if (th->rst) printk("RST "); if (th->syn) printk("SYN "); if (th->fin) printk("FIN "); /* Max length: 11 "URGP=65535 " */ printk("URGP=%u ", ntohs(th->urg_ptr)); if ((logflags & IPT_LOG_TCPOPT) && th->doff * 4 > sizeof(struct tcphdr)) { unsigned char _opt[4 * 15 - sizeof(struct tcphdr)]; const unsigned char *op; unsigned int i, optsize; optsize = th->doff * 4 - sizeof(struct tcphdr); op = skb_header_pointer(skb, iphoff+ih->ihl*4+sizeof(_tcph), optsize, _opt); if (op == NULL) { printk("TRUNCATED"); return; } /* Max length: 127 "OPT (" 15*4*2chars ") " */ printk("OPT ("); for (i = 0; i < optsize; i++) printk("%02X", op[i]); printk(") "); } break; } case IPPROTO_UDP: case IPPROTO_UDPLITE: { struct udphdr _udph; const struct udphdr *uh; if (ih->protocol == IPPROTO_UDP) /* Max length: 10 "PROTO=UDP " */ printk("PROTO=UDP " ); else /* Max length: 14 "PROTO=UDPLITE " */ printk("PROTO=UDPLITE "); if (ntohs(ih->frag_off) & IP_OFFSET) break; /* Max length: 25 "INCOMPLETE [65535 bytes] " */ uh = skb_header_pointer(skb, iphoff+ih->ihl*4, sizeof(_udph), &_udph); if (uh == NULL) { printk("INCOMPLETE [%u bytes] ", skb->len - iphoff - ih->ihl*4); break; } /* Max length: 20 "SPT=65535 DPT=65535 " */ printk("SPT=%u DPT=%u LEN=%u ", ntohs(uh->source), ntohs(uh->dest), ntohs(uh->len)); break; } case IPPROTO_ICMP: { struct icmphdr _icmph; const struct icmphdr *ich; static const size_t required_len[NR_ICMP_TYPES+1] = { [ICMP_ECHOREPLY] = 4, [ICMP_DEST_UNREACH] = 8 + sizeof(struct iphdr), [ICMP_SOURCE_QUENCH] = 8 + sizeof(struct iphdr), [ICMP_REDIRECT] = 8 + sizeof(struct iphdr), [ICMP_ECHO] = 4, [ICMP_TIME_EXCEEDED] = 8 + sizeof(struct iphdr), [ICMP_PARAMETERPROB] = 8 + sizeof(struct iphdr), [ICMP_TIMESTAMP] = 20, [ICMP_TIMESTAMPREPLY] = 20, [ICMP_ADDRESS] = 12, [ICMP_ADDRESSREPLY] = 12 }; /* Max length: 11 "PROTO=ICMP " */ printk("PROTO=ICMP "); if (ntohs(ih->frag_off) & IP_OFFSET) break; /* Max length: 25 "INCOMPLETE [65535 bytes] " */ ich = skb_header_pointer(skb, iphoff + ih->ihl * 4, sizeof(_icmph), &_icmph); if (ich == NULL) { printk("INCOMPLETE [%u bytes] ", skb->len - iphoff - ih->ihl*4); break; } /* Max length: 18 "TYPE=255 CODE=255 " */ printk("TYPE=%u CODE=%u ", ich->type, ich->code); /* Max length: 25 "INCOMPLETE [65535 bytes] " */ if (ich->type <= NR_ICMP_TYPES && required_len[ich->type] && skb->len-iphoff-ih->ihl*4 < required_len[ich->type]) { printk("INCOMPLETE [%u bytes] ", skb->len - iphoff - ih->ihl*4); break; } switch (ich->type) { case ICMP_ECHOREPLY: case ICMP_ECHO: /* Max length: 19 "ID=65535 SEQ=65535 " */ printk("ID=%u SEQ=%u ", ntohs(ich->un.echo.id), ntohs(ich->un.echo.sequence)); break; case ICMP_PARAMETERPROB: /* Max length: 14 "PARAMETER=255 " */ printk("PARAMETER=%u ", ntohl(ich->un.gateway) >> 24); break; case ICMP_REDIRECT: /* Max length: 24 "GATEWAY=255.255.255.255 " */ printk("GATEWAY=%pI4 ", &ich->un.gateway); /* Fall through */ case ICMP_DEST_UNREACH: case ICMP_SOURCE_QUENCH: case ICMP_TIME_EXCEEDED: /* Max length: 3+maxlen */ if (!iphoff) { /* Only recurse once. */ printk("["); dump_packet(info, skb, iphoff + ih->ihl*4+sizeof(_icmph)); printk("] "); } /* Max length: 10 "MTU=65535 " */ if (ich->type == ICMP_DEST_UNREACH && ich->code == ICMP_FRAG_NEEDED) printk("MTU=%u ", ntohs(ich->un.frag.mtu)); } break; } /* Max Length */ case IPPROTO_AH: { struct ip_auth_hdr _ahdr; const struct ip_auth_hdr *ah; if (ntohs(ih->frag_off) & IP_OFFSET) break; /* Max length: 9 "PROTO=AH " */ printk("PROTO=AH "); /* Max length: 25 "INCOMPLETE [65535 bytes] " */ ah = skb_header_pointer(skb, iphoff+ih->ihl*4, sizeof(_ahdr), &_ahdr); if (ah == NULL) { printk("INCOMPLETE [%u bytes] ", skb->len - iphoff - ih->ihl*4); break; } /* Length: 15 "SPI=0xF1234567 " */ printk("SPI=0x%x ", ntohl(ah->spi)); break; } case IPPROTO_ESP: { struct ip_esp_hdr _esph; const struct ip_esp_hdr *eh; /* Max length: 10 "PROTO=ESP " */ printk("PROTO=ESP "); if (ntohs(ih->frag_off) & IP_OFFSET) break; /* Max length: 25 "INCOMPLETE [65535 bytes] " */ eh = skb_header_pointer(skb, iphoff+ih->ihl*4, sizeof(_esph), &_esph); if (eh == NULL) { printk("INCOMPLETE [%u bytes] ", skb->len - iphoff - ih->ihl*4); break; } /* Length: 15 "SPI=0xF1234567 " */ printk("SPI=0x%x ", ntohl(eh->spi)); break; } /* Max length: 10 "PROTO 255 " */ default: printk("PROTO=%u ", ih->protocol); } /* Max length: 15 "UID=4294967295 " */ if ((logflags & IPT_LOG_UID) && !iphoff && skb->sk) { read_lock_bh(&skb->sk->sk_callback_lock); if (skb->sk->sk_socket && skb->sk->sk_socket->file) printk("UID=%u GID=%u ", skb->sk->sk_socket->file->f_cred->fsuid, skb->sk->sk_socket->file->f_cred->fsgid); read_unlock_bh(&skb->sk->sk_callback_lock); } /* Max length: 16 "MARK=0xFFFFFFFF " */ if (!iphoff && skb->mark) printk("MARK=0x%x ", skb->mark); /* Proto Max log string length */ /* IP: 40+46+6+11+127 = 230 */ /* TCP: 10+max(25,20+30+13+9+32+11+127) = 252 */ /* UDP: 10+max(25,20) = 35 */ /* UDPLITE: 14+max(25,20) = 39 */ /* ICMP: 11+max(25, 18+25+max(19,14,24+3+n+10,3+n+10)) = 91+n */ /* ESP: 10+max(25)+15 = 50 */ /* AH: 9+max(25)+15 = 49 */ /* unknown: 10 */ /* (ICMP allows recursion one level deep) */ /* maxlen = IP + ICMP + IP + max(TCP,UDP,ICMP,unknown) */ /* maxlen = 230+ 91 + 230 + 252 = 803 */ } static struct nf_loginfo default_loginfo = { .type = NF_LOG_TYPE_LOG, .u = { .log = { .level = 0, .logflags = NF_LOG_MASK, }, }, }; static void ipt_log_packet(u_int8_t pf, unsigned int hooknum, const struct sk_buff *skb, const struct net_device *in, const struct net_device *out, const struct nf_loginfo *loginfo, const char *prefix) { if (!loginfo) loginfo = &default_loginfo; spin_lock_bh(&log_lock); printk("<%d>%sIN=%s OUT=%s ", loginfo->u.log.level, prefix, in ? in->name : "", out ? out->name : ""); #ifdef CONFIG_BRIDGE_NETFILTER if (skb->nf_bridge) { const struct net_device *physindev; const struct net_device *physoutdev; physindev = skb->nf_bridge->physindev; if (physindev && in != physindev) printk("PHYSIN=%s ", physindev->name); physoutdev = skb->nf_bridge->physoutdev; if (physoutdev && out != physoutdev) printk("PHYSOUT=%s ", physoutdev->name); } #endif if (in && !out) { /* MAC logging for input chain only. */ printk("MAC="); if (skb->dev && skb->dev->hard_header_len && skb->mac_header != skb->network_header) { int i; const unsigned char *p = skb_mac_header(skb); for (i = 0; i < skb->dev->hard_header_len; i++,p++) printk("%02x%c", *p, i==skb->dev->hard_header_len - 1 ? ' ':':'); } else printk(" "); } dump_packet(loginfo, skb, 0); printk("\n"); spin_unlock_bh(&log_lock); } static unsigned int log_tg(struct sk_buff *skb, const struct xt_target_param *par) { const struct ipt_log_info *loginfo = par->targinfo; struct nf_loginfo li; li.type = NF_LOG_TYPE_LOG; li.u.log.level = loginfo->level; li.u.log.logflags = loginfo->logflags; ipt_log_packet(NFPROTO_IPV4, par->hooknum, skb, par->in, par->out, &li, loginfo->prefix); return XT_CONTINUE; } static bool log_tg_check(const struct xt_tgchk_param *par) { const struct ipt_log_info *loginfo = par->targinfo; if (loginfo->level >= 8) { pr_debug("LOG: level %u >= 8\n", loginfo->level); return false; } if (loginfo->prefix[sizeof(loginfo->prefix)-1] != '\0') { pr_debug("LOG: prefix term %i\n", loginfo->prefix[sizeof(loginfo->prefix)-1]); return false; } return true; } 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);