1 /*
2 * This is a module which is used for logging packets.
3 */
4
5 /* (C) 1999-2001 Paul `Rusty' Russell
6 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 */
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13 #include <linux/module.h>
14 #include <linux/spinlock.h>
15 #include <linux/skbuff.h>
16 #include <linux/if_arp.h>
17 #include <linux/ip.h>
18 #include <net/icmp.h>
19 #include <net/udp.h>
20 #include <net/tcp.h>
21 #include <net/route.h>
22
23 #include <linux/netfilter.h>
24 #include <linux/netfilter/x_tables.h>
25 #include <linux/netfilter_ipv4/ipt_LOG.h>
26 #include <net/netfilter/nf_log.h>
27 #include <net/netfilter/xt_log.h>
28
29 MODULE_LICENSE("GPL");
30 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
31 MODULE_DESCRIPTION("Xtables: IPv4 packet logging to syslog");
32
33 /* One level of recursion won't kill us */
dump_packet(struct sbuff * m,const struct nf_loginfo * info,const struct sk_buff * skb,unsigned int iphoff)34 static void dump_packet(struct sbuff *m,
35 const struct nf_loginfo *info,
36 const struct sk_buff *skb,
37 unsigned int iphoff)
38 {
39 struct iphdr _iph;
40 const struct iphdr *ih;
41 unsigned int logflags;
42
43 if (info->type == NF_LOG_TYPE_LOG)
44 logflags = info->u.log.logflags;
45 else
46 logflags = NF_LOG_MASK;
47
48 ih = skb_header_pointer(skb, iphoff, sizeof(_iph), &_iph);
49 if (ih == NULL) {
50 sb_add(m, "TRUNCATED");
51 return;
52 }
53
54 /* Important fields:
55 * TOS, len, DF/MF, fragment offset, TTL, src, dst, options. */
56 /* Max length: 40 "SRC=255.255.255.255 DST=255.255.255.255 " */
57 sb_add(m, "SRC=%pI4 DST=%pI4 ",
58 &ih->saddr, &ih->daddr);
59
60 /* Max length: 46 "LEN=65535 TOS=0xFF PREC=0xFF TTL=255 ID=65535 " */
61 sb_add(m, "LEN=%u TOS=0x%02X PREC=0x%02X TTL=%u ID=%u ",
62 ntohs(ih->tot_len), ih->tos & IPTOS_TOS_MASK,
63 ih->tos & IPTOS_PREC_MASK, ih->ttl, ntohs(ih->id));
64
65 /* Max length: 6 "CE DF MF " */
66 if (ntohs(ih->frag_off) & IP_CE)
67 sb_add(m, "CE ");
68 if (ntohs(ih->frag_off) & IP_DF)
69 sb_add(m, "DF ");
70 if (ntohs(ih->frag_off) & IP_MF)
71 sb_add(m, "MF ");
72
73 /* Max length: 11 "FRAG:65535 " */
74 if (ntohs(ih->frag_off) & IP_OFFSET)
75 sb_add(m, "FRAG:%u ", ntohs(ih->frag_off) & IP_OFFSET);
76
77 if ((logflags & IPT_LOG_IPOPT) &&
78 ih->ihl * 4 > sizeof(struct iphdr)) {
79 const unsigned char *op;
80 unsigned char _opt[4 * 15 - sizeof(struct iphdr)];
81 unsigned int i, optsize;
82
83 optsize = ih->ihl * 4 - sizeof(struct iphdr);
84 op = skb_header_pointer(skb, iphoff+sizeof(_iph),
85 optsize, _opt);
86 if (op == NULL) {
87 sb_add(m, "TRUNCATED");
88 return;
89 }
90
91 /* Max length: 127 "OPT (" 15*4*2chars ") " */
92 sb_add(m, "OPT (");
93 for (i = 0; i < optsize; i++)
94 sb_add(m, "%02X", op[i]);
95 sb_add(m, ") ");
96 }
97
98 switch (ih->protocol) {
99 case IPPROTO_TCP: {
100 struct tcphdr _tcph;
101 const struct tcphdr *th;
102
103 /* Max length: 10 "PROTO=TCP " */
104 sb_add(m, "PROTO=TCP ");
105
106 if (ntohs(ih->frag_off) & IP_OFFSET)
107 break;
108
109 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
110 th = skb_header_pointer(skb, iphoff + ih->ihl * 4,
111 sizeof(_tcph), &_tcph);
112 if (th == NULL) {
113 sb_add(m, "INCOMPLETE [%u bytes] ",
114 skb->len - iphoff - ih->ihl*4);
115 break;
116 }
117
118 /* Max length: 20 "SPT=65535 DPT=65535 " */
119 sb_add(m, "SPT=%u DPT=%u ",
120 ntohs(th->source), ntohs(th->dest));
121 /* Max length: 30 "SEQ=4294967295 ACK=4294967295 " */
122 if (logflags & IPT_LOG_TCPSEQ)
123 sb_add(m, "SEQ=%u ACK=%u ",
124 ntohl(th->seq), ntohl(th->ack_seq));
125 /* Max length: 13 "WINDOW=65535 " */
126 sb_add(m, "WINDOW=%u ", ntohs(th->window));
127 /* Max length: 9 "RES=0x3F " */
128 sb_add(m, "RES=0x%02x ", (u8)(ntohl(tcp_flag_word(th) & TCP_RESERVED_BITS) >> 22));
129 /* Max length: 32 "CWR ECE URG ACK PSH RST SYN FIN " */
130 if (th->cwr)
131 sb_add(m, "CWR ");
132 if (th->ece)
133 sb_add(m, "ECE ");
134 if (th->urg)
135 sb_add(m, "URG ");
136 if (th->ack)
137 sb_add(m, "ACK ");
138 if (th->psh)
139 sb_add(m, "PSH ");
140 if (th->rst)
141 sb_add(m, "RST ");
142 if (th->syn)
143 sb_add(m, "SYN ");
144 if (th->fin)
145 sb_add(m, "FIN ");
146 /* Max length: 11 "URGP=65535 " */
147 sb_add(m, "URGP=%u ", ntohs(th->urg_ptr));
148
149 if ((logflags & IPT_LOG_TCPOPT) &&
150 th->doff * 4 > sizeof(struct tcphdr)) {
151 unsigned char _opt[4 * 15 - sizeof(struct tcphdr)];
152 const unsigned char *op;
153 unsigned int i, optsize;
154
155 optsize = th->doff * 4 - sizeof(struct tcphdr);
156 op = skb_header_pointer(skb,
157 iphoff+ih->ihl*4+sizeof(_tcph),
158 optsize, _opt);
159 if (op == NULL) {
160 sb_add(m, "TRUNCATED");
161 return;
162 }
163
164 /* Max length: 127 "OPT (" 15*4*2chars ") " */
165 sb_add(m, "OPT (");
166 for (i = 0; i < optsize; i++)
167 sb_add(m, "%02X", op[i]);
168 sb_add(m, ") ");
169 }
170 break;
171 }
172 case IPPROTO_UDP:
173 case IPPROTO_UDPLITE: {
174 struct udphdr _udph;
175 const struct udphdr *uh;
176
177 if (ih->protocol == IPPROTO_UDP)
178 /* Max length: 10 "PROTO=UDP " */
179 sb_add(m, "PROTO=UDP " );
180 else /* Max length: 14 "PROTO=UDPLITE " */
181 sb_add(m, "PROTO=UDPLITE ");
182
183 if (ntohs(ih->frag_off) & IP_OFFSET)
184 break;
185
186 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
187 uh = skb_header_pointer(skb, iphoff+ih->ihl*4,
188 sizeof(_udph), &_udph);
189 if (uh == NULL) {
190 sb_add(m, "INCOMPLETE [%u bytes] ",
191 skb->len - iphoff - ih->ihl*4);
192 break;
193 }
194
195 /* Max length: 20 "SPT=65535 DPT=65535 " */
196 sb_add(m, "SPT=%u DPT=%u LEN=%u ",
197 ntohs(uh->source), ntohs(uh->dest),
198 ntohs(uh->len));
199 break;
200 }
201 case IPPROTO_ICMP: {
202 struct icmphdr _icmph;
203 const struct icmphdr *ich;
204 static const size_t required_len[NR_ICMP_TYPES+1]
205 = { [ICMP_ECHOREPLY] = 4,
206 [ICMP_DEST_UNREACH]
207 = 8 + sizeof(struct iphdr),
208 [ICMP_SOURCE_QUENCH]
209 = 8 + sizeof(struct iphdr),
210 [ICMP_REDIRECT]
211 = 8 + sizeof(struct iphdr),
212 [ICMP_ECHO] = 4,
213 [ICMP_TIME_EXCEEDED]
214 = 8 + sizeof(struct iphdr),
215 [ICMP_PARAMETERPROB]
216 = 8 + sizeof(struct iphdr),
217 [ICMP_TIMESTAMP] = 20,
218 [ICMP_TIMESTAMPREPLY] = 20,
219 [ICMP_ADDRESS] = 12,
220 [ICMP_ADDRESSREPLY] = 12 };
221
222 /* Max length: 11 "PROTO=ICMP " */
223 sb_add(m, "PROTO=ICMP ");
224
225 if (ntohs(ih->frag_off) & IP_OFFSET)
226 break;
227
228 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
229 ich = skb_header_pointer(skb, iphoff + ih->ihl * 4,
230 sizeof(_icmph), &_icmph);
231 if (ich == NULL) {
232 sb_add(m, "INCOMPLETE [%u bytes] ",
233 skb->len - iphoff - ih->ihl*4);
234 break;
235 }
236
237 /* Max length: 18 "TYPE=255 CODE=255 " */
238 sb_add(m, "TYPE=%u CODE=%u ", ich->type, ich->code);
239
240 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
241 if (ich->type <= NR_ICMP_TYPES &&
242 required_len[ich->type] &&
243 skb->len-iphoff-ih->ihl*4 < required_len[ich->type]) {
244 sb_add(m, "INCOMPLETE [%u bytes] ",
245 skb->len - iphoff - ih->ihl*4);
246 break;
247 }
248
249 switch (ich->type) {
250 case ICMP_ECHOREPLY:
251 case ICMP_ECHO:
252 /* Max length: 19 "ID=65535 SEQ=65535 " */
253 sb_add(m, "ID=%u SEQ=%u ",
254 ntohs(ich->un.echo.id),
255 ntohs(ich->un.echo.sequence));
256 break;
257
258 case ICMP_PARAMETERPROB:
259 /* Max length: 14 "PARAMETER=255 " */
260 sb_add(m, "PARAMETER=%u ",
261 ntohl(ich->un.gateway) >> 24);
262 break;
263 case ICMP_REDIRECT:
264 /* Max length: 24 "GATEWAY=255.255.255.255 " */
265 sb_add(m, "GATEWAY=%pI4 ", &ich->un.gateway);
266 /* Fall through */
267 case ICMP_DEST_UNREACH:
268 case ICMP_SOURCE_QUENCH:
269 case ICMP_TIME_EXCEEDED:
270 /* Max length: 3+maxlen */
271 if (!iphoff) { /* Only recurse once. */
272 sb_add(m, "[");
273 dump_packet(m, info, skb,
274 iphoff + ih->ihl*4+sizeof(_icmph));
275 sb_add(m, "] ");
276 }
277
278 /* Max length: 10 "MTU=65535 " */
279 if (ich->type == ICMP_DEST_UNREACH &&
280 ich->code == ICMP_FRAG_NEEDED)
281 sb_add(m, "MTU=%u ", ntohs(ich->un.frag.mtu));
282 }
283 break;
284 }
285 /* Max Length */
286 case IPPROTO_AH: {
287 struct ip_auth_hdr _ahdr;
288 const struct ip_auth_hdr *ah;
289
290 if (ntohs(ih->frag_off) & IP_OFFSET)
291 break;
292
293 /* Max length: 9 "PROTO=AH " */
294 sb_add(m, "PROTO=AH ");
295
296 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
297 ah = skb_header_pointer(skb, iphoff+ih->ihl*4,
298 sizeof(_ahdr), &_ahdr);
299 if (ah == NULL) {
300 sb_add(m, "INCOMPLETE [%u bytes] ",
301 skb->len - iphoff - ih->ihl*4);
302 break;
303 }
304
305 /* Length: 15 "SPI=0xF1234567 " */
306 sb_add(m, "SPI=0x%x ", ntohl(ah->spi));
307 break;
308 }
309 case IPPROTO_ESP: {
310 struct ip_esp_hdr _esph;
311 const struct ip_esp_hdr *eh;
312
313 /* Max length: 10 "PROTO=ESP " */
314 sb_add(m, "PROTO=ESP ");
315
316 if (ntohs(ih->frag_off) & IP_OFFSET)
317 break;
318
319 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
320 eh = skb_header_pointer(skb, iphoff+ih->ihl*4,
321 sizeof(_esph), &_esph);
322 if (eh == NULL) {
323 sb_add(m, "INCOMPLETE [%u bytes] ",
324 skb->len - iphoff - ih->ihl*4);
325 break;
326 }
327
328 /* Length: 15 "SPI=0xF1234567 " */
329 sb_add(m, "SPI=0x%x ", ntohl(eh->spi));
330 break;
331 }
332 /* Max length: 10 "PROTO 255 " */
333 default:
334 sb_add(m, "PROTO=%u ", ih->protocol);
335 }
336
337 /* Max length: 15 "UID=4294967295 " */
338 if ((logflags & IPT_LOG_UID) && !iphoff && skb->sk) {
339 read_lock_bh(&skb->sk->sk_callback_lock);
340 if (skb->sk->sk_socket && skb->sk->sk_socket->file)
341 sb_add(m, "UID=%u GID=%u ",
342 skb->sk->sk_socket->file->f_cred->fsuid,
343 skb->sk->sk_socket->file->f_cred->fsgid);
344 read_unlock_bh(&skb->sk->sk_callback_lock);
345 }
346
347 /* Max length: 16 "MARK=0xFFFFFFFF " */
348 if (!iphoff && skb->mark)
349 sb_add(m, "MARK=0x%x ", skb->mark);
350
351 /* Proto Max log string length */
352 /* IP: 40+46+6+11+127 = 230 */
353 /* TCP: 10+max(25,20+30+13+9+32+11+127) = 252 */
354 /* UDP: 10+max(25,20) = 35 */
355 /* UDPLITE: 14+max(25,20) = 39 */
356 /* ICMP: 11+max(25, 18+25+max(19,14,24+3+n+10,3+n+10)) = 91+n */
357 /* ESP: 10+max(25)+15 = 50 */
358 /* AH: 9+max(25)+15 = 49 */
359 /* unknown: 10 */
360
361 /* (ICMP allows recursion one level deep) */
362 /* maxlen = IP + ICMP + IP + max(TCP,UDP,ICMP,unknown) */
363 /* maxlen = 230+ 91 + 230 + 252 = 803 */
364 }
365
dump_mac_header(struct sbuff * m,const struct nf_loginfo * info,const struct sk_buff * skb)366 static void dump_mac_header(struct sbuff *m,
367 const struct nf_loginfo *info,
368 const struct sk_buff *skb)
369 {
370 struct net_device *dev = skb->dev;
371 unsigned int logflags = 0;
372
373 if (info->type == NF_LOG_TYPE_LOG)
374 logflags = info->u.log.logflags;
375
376 if (!(logflags & IPT_LOG_MACDECODE))
377 goto fallback;
378
379 switch (dev->type) {
380 case ARPHRD_ETHER:
381 sb_add(m, "MACSRC=%pM MACDST=%pM MACPROTO=%04x ",
382 eth_hdr(skb)->h_source, eth_hdr(skb)->h_dest,
383 ntohs(eth_hdr(skb)->h_proto));
384 return;
385 default:
386 break;
387 }
388
389 fallback:
390 sb_add(m, "MAC=");
391 if (dev->hard_header_len &&
392 skb->mac_header != skb->network_header) {
393 const unsigned char *p = skb_mac_header(skb);
394 unsigned int i;
395
396 sb_add(m, "%02x", *p++);
397 for (i = 1; i < dev->hard_header_len; i++, p++)
398 sb_add(m, ":%02x", *p);
399 }
400 sb_add(m, " ");
401 }
402
403 static struct nf_loginfo default_loginfo = {
404 .type = NF_LOG_TYPE_LOG,
405 .u = {
406 .log = {
407 .level = 5,
408 .logflags = NF_LOG_MASK,
409 },
410 },
411 };
412
413 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)414 ipt_log_packet(u_int8_t pf,
415 unsigned int hooknum,
416 const struct sk_buff *skb,
417 const struct net_device *in,
418 const struct net_device *out,
419 const struct nf_loginfo *loginfo,
420 const char *prefix)
421 {
422 struct sbuff *m = sb_open();
423
424 if (!loginfo)
425 loginfo = &default_loginfo;
426
427 sb_add(m, "<%d>%sIN=%s OUT=%s ", loginfo->u.log.level,
428 prefix,
429 in ? in->name : "",
430 out ? out->name : "");
431 #ifdef CONFIG_BRIDGE_NETFILTER
432 if (skb->nf_bridge) {
433 const struct net_device *physindev;
434 const struct net_device *physoutdev;
435
436 physindev = skb->nf_bridge->physindev;
437 if (physindev && in != physindev)
438 sb_add(m, "PHYSIN=%s ", physindev->name);
439 physoutdev = skb->nf_bridge->physoutdev;
440 if (physoutdev && out != physoutdev)
441 sb_add(m, "PHYSOUT=%s ", physoutdev->name);
442 }
443 #endif
444
445 if (in != NULL)
446 dump_mac_header(m, loginfo, skb);
447
448 dump_packet(m, loginfo, skb, 0);
449
450 sb_close(m);
451 }
452
453 static unsigned int
log_tg(struct sk_buff * skb,const struct xt_action_param * par)454 log_tg(struct sk_buff *skb, const struct xt_action_param *par)
455 {
456 const struct ipt_log_info *loginfo = par->targinfo;
457 struct nf_loginfo li;
458
459 li.type = NF_LOG_TYPE_LOG;
460 li.u.log.level = loginfo->level;
461 li.u.log.logflags = loginfo->logflags;
462
463 ipt_log_packet(NFPROTO_IPV4, par->hooknum, skb, par->in, par->out, &li,
464 loginfo->prefix);
465 return XT_CONTINUE;
466 }
467
log_tg_check(const struct xt_tgchk_param * par)468 static int log_tg_check(const struct xt_tgchk_param *par)
469 {
470 const struct ipt_log_info *loginfo = par->targinfo;
471
472 if (loginfo->level >= 8) {
473 pr_debug("level %u >= 8\n", loginfo->level);
474 return -EINVAL;
475 }
476 if (loginfo->prefix[sizeof(loginfo->prefix)-1] != '\0') {
477 pr_debug("prefix is not null-terminated\n");
478 return -EINVAL;
479 }
480 return 0;
481 }
482
483 static struct xt_target log_tg_reg __read_mostly = {
484 .name = "LOG",
485 .family = NFPROTO_IPV4,
486 .target = log_tg,
487 .targetsize = sizeof(struct ipt_log_info),
488 .checkentry = log_tg_check,
489 .me = THIS_MODULE,
490 };
491
492 static struct nf_logger ipt_log_logger __read_mostly = {
493 .name = "ipt_LOG",
494 .logfn = &ipt_log_packet,
495 .me = THIS_MODULE,
496 };
497
log_tg_init(void)498 static int __init log_tg_init(void)
499 {
500 int ret;
501
502 ret = xt_register_target(&log_tg_reg);
503 if (ret < 0)
504 return ret;
505 nf_log_register(NFPROTO_IPV4, &ipt_log_logger);
506 return 0;
507 }
508
log_tg_exit(void)509 static void __exit log_tg_exit(void)
510 {
511 nf_log_unregister(&ipt_log_logger);
512 xt_unregister_target(&log_tg_reg);
513 }
514
515 module_init(log_tg_init);
516 module_exit(log_tg_exit);
517