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netfilter: ip6t_LOG: fix a flaw in printing the MAC
[linux-3.10.git] / net / ipv6 / netfilter / ip6t_LOG.c
1 /*
2  * This is a module which is used for logging packets.
3  */
4
5 /* (C) 2001 Jan Rekorajski <baggins@pld.org.pl>
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/skbuff.h>
15 #include <linux/if_arp.h>
16 #include <linux/ip.h>
17 #include <linux/spinlock.h>
18 #include <linux/icmpv6.h>
19 #include <net/udp.h>
20 #include <net/tcp.h>
21 #include <net/ipv6.h>
22 #include <linux/netfilter.h>
23 #include <linux/netfilter/x_tables.h>
24 #include <linux/netfilter_ipv6/ip6_tables.h>
25 #include <net/netfilter/nf_log.h>
26 #include <net/netfilter/xt_log.h>
27
28 MODULE_AUTHOR("Jan Rekorajski <baggins@pld.org.pl>");
29 MODULE_DESCRIPTION("Xtables: IPv6 packet logging to syslog");
30 MODULE_LICENSE("GPL");
31
32 struct in_device;
33 #include <net/route.h>
34 #include <linux/netfilter_ipv6/ip6t_LOG.h>
35
36 /* One level of recursion won't kill us */
37 static void dump_packet(struct sbuff *m,
38                         const struct nf_loginfo *info,
39                         const struct sk_buff *skb, unsigned int ip6hoff,
40                         int recurse)
41 {
42         u_int8_t currenthdr;
43         int fragment;
44         struct ipv6hdr _ip6h;
45         const struct ipv6hdr *ih;
46         unsigned int ptr;
47         unsigned int hdrlen = 0;
48         unsigned int logflags;
49
50         if (info->type == NF_LOG_TYPE_LOG)
51                 logflags = info->u.log.logflags;
52         else
53                 logflags = NF_LOG_MASK;
54
55         ih = skb_header_pointer(skb, ip6hoff, sizeof(_ip6h), &_ip6h);
56         if (ih == NULL) {
57                 sb_add(m, "TRUNCATED");
58                 return;
59         }
60
61         /* Max length: 88 "SRC=0000.0000.0000.0000.0000.0000.0000.0000 DST=0000.0000.0000.0000.0000.0000.0000.0000 " */
62         sb_add(m, "SRC=%pI6 DST=%pI6 ", &ih->saddr, &ih->daddr);
63
64         /* Max length: 44 "LEN=65535 TC=255 HOPLIMIT=255 FLOWLBL=FFFFF " */
65         sb_add(m, "LEN=%Zu TC=%u HOPLIMIT=%u FLOWLBL=%u ",
66                ntohs(ih->payload_len) + sizeof(struct ipv6hdr),
67                (ntohl(*(__be32 *)ih) & 0x0ff00000) >> 20,
68                ih->hop_limit,
69                (ntohl(*(__be32 *)ih) & 0x000fffff));
70
71         fragment = 0;
72         ptr = ip6hoff + sizeof(struct ipv6hdr);
73         currenthdr = ih->nexthdr;
74         while (currenthdr != NEXTHDR_NONE && ip6t_ext_hdr(currenthdr)) {
75                 struct ipv6_opt_hdr _hdr;
76                 const struct ipv6_opt_hdr *hp;
77
78                 hp = skb_header_pointer(skb, ptr, sizeof(_hdr), &_hdr);
79                 if (hp == NULL) {
80                         sb_add(m, "TRUNCATED");
81                         return;
82                 }
83
84                 /* Max length: 48 "OPT (...) " */
85                 if (logflags & IP6T_LOG_IPOPT)
86                         sb_add(m, "OPT ( ");
87
88                 switch (currenthdr) {
89                 case IPPROTO_FRAGMENT: {
90                         struct frag_hdr _fhdr;
91                         const struct frag_hdr *fh;
92
93                         sb_add(m, "FRAG:");
94                         fh = skb_header_pointer(skb, ptr, sizeof(_fhdr),
95                                                 &_fhdr);
96                         if (fh == NULL) {
97                                 sb_add(m, "TRUNCATED ");
98                                 return;
99                         }
100
101                         /* Max length: 6 "65535 " */
102                         sb_add(m, "%u ", ntohs(fh->frag_off) & 0xFFF8);
103
104                         /* Max length: 11 "INCOMPLETE " */
105                         if (fh->frag_off & htons(0x0001))
106                                 sb_add(m, "INCOMPLETE ");
107
108                         sb_add(m, "ID:%08x ", ntohl(fh->identification));
109
110                         if (ntohs(fh->frag_off) & 0xFFF8)
111                                 fragment = 1;
112
113                         hdrlen = 8;
114
115                         break;
116                 }
117                 case IPPROTO_DSTOPTS:
118                 case IPPROTO_ROUTING:
119                 case IPPROTO_HOPOPTS:
120                         if (fragment) {
121                                 if (logflags & IP6T_LOG_IPOPT)
122                                         sb_add(m, ")");
123                                 return;
124                         }
125                         hdrlen = ipv6_optlen(hp);
126                         break;
127                 /* Max Length */
128                 case IPPROTO_AH:
129                         if (logflags & IP6T_LOG_IPOPT) {
130                                 struct ip_auth_hdr _ahdr;
131                                 const struct ip_auth_hdr *ah;
132
133                                 /* Max length: 3 "AH " */
134                                 sb_add(m, "AH ");
135
136                                 if (fragment) {
137                                         sb_add(m, ")");
138                                         return;
139                                 }
140
141                                 ah = skb_header_pointer(skb, ptr, sizeof(_ahdr),
142                                                         &_ahdr);
143                                 if (ah == NULL) {
144                                         /*
145                                          * Max length: 26 "INCOMPLETE [65535
146                                          *  bytes] )"
147                                          */
148                                         sb_add(m, "INCOMPLETE [%u bytes] )",
149                                                skb->len - ptr);
150                                         return;
151                                 }
152
153                                 /* Length: 15 "SPI=0xF1234567 */
154                                 sb_add(m, "SPI=0x%x ", ntohl(ah->spi));
155
156                         }
157
158                         hdrlen = (hp->hdrlen+2)<<2;
159                         break;
160                 case IPPROTO_ESP:
161                         if (logflags & IP6T_LOG_IPOPT) {
162                                 struct ip_esp_hdr _esph;
163                                 const struct ip_esp_hdr *eh;
164
165                                 /* Max length: 4 "ESP " */
166                                 sb_add(m, "ESP ");
167
168                                 if (fragment) {
169                                         sb_add(m, ")");
170                                         return;
171                                 }
172
173                                 /*
174                                  * Max length: 26 "INCOMPLETE [65535 bytes] )"
175                                  */
176                                 eh = skb_header_pointer(skb, ptr, sizeof(_esph),
177                                                         &_esph);
178                                 if (eh == NULL) {
179                                         sb_add(m, "INCOMPLETE [%u bytes] )",
180                                                skb->len - ptr);
181                                         return;
182                                 }
183
184                                 /* Length: 16 "SPI=0xF1234567 )" */
185                                 sb_add(m, "SPI=0x%x )", ntohl(eh->spi) );
186
187                         }
188                         return;
189                 default:
190                         /* Max length: 20 "Unknown Ext Hdr 255" */
191                         sb_add(m, "Unknown Ext Hdr %u", currenthdr);
192                         return;
193                 }
194                 if (logflags & IP6T_LOG_IPOPT)
195                         sb_add(m, ") ");
196
197                 currenthdr = hp->nexthdr;
198                 ptr += hdrlen;
199         }
200
201         switch (currenthdr) {
202         case IPPROTO_TCP: {
203                 struct tcphdr _tcph;
204                 const struct tcphdr *th;
205
206                 /* Max length: 10 "PROTO=TCP " */
207                 sb_add(m, "PROTO=TCP ");
208
209                 if (fragment)
210                         break;
211
212                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
213                 th = skb_header_pointer(skb, ptr, sizeof(_tcph), &_tcph);
214                 if (th == NULL) {
215                         sb_add(m, "INCOMPLETE [%u bytes] ", skb->len - ptr);
216                         return;
217                 }
218
219                 /* Max length: 20 "SPT=65535 DPT=65535 " */
220                 sb_add(m, "SPT=%u DPT=%u ",
221                        ntohs(th->source), ntohs(th->dest));
222                 /* Max length: 30 "SEQ=4294967295 ACK=4294967295 " */
223                 if (logflags & IP6T_LOG_TCPSEQ)
224                         sb_add(m, "SEQ=%u ACK=%u ",
225                                ntohl(th->seq), ntohl(th->ack_seq));
226                 /* Max length: 13 "WINDOW=65535 " */
227                 sb_add(m, "WINDOW=%u ", ntohs(th->window));
228                 /* Max length: 9 "RES=0x3C " */
229                 sb_add(m, "RES=0x%02x ", (u_int8_t)(ntohl(tcp_flag_word(th) & TCP_RESERVED_BITS) >> 22));
230                 /* Max length: 32 "CWR ECE URG ACK PSH RST SYN FIN " */
231                 if (th->cwr)
232                         sb_add(m, "CWR ");
233                 if (th->ece)
234                         sb_add(m, "ECE ");
235                 if (th->urg)
236                         sb_add(m, "URG ");
237                 if (th->ack)
238                         sb_add(m, "ACK ");
239                 if (th->psh)
240                         sb_add(m, "PSH ");
241                 if (th->rst)
242                         sb_add(m, "RST ");
243                 if (th->syn)
244                         sb_add(m, "SYN ");
245                 if (th->fin)
246                         sb_add(m, "FIN ");
247                 /* Max length: 11 "URGP=65535 " */
248                 sb_add(m, "URGP=%u ", ntohs(th->urg_ptr));
249
250                 if ((logflags & IP6T_LOG_TCPOPT) &&
251                     th->doff * 4 > sizeof(struct tcphdr)) {
252                         u_int8_t _opt[60 - sizeof(struct tcphdr)];
253                         const u_int8_t *op;
254                         unsigned int i;
255                         unsigned int optsize = th->doff * 4
256                                                - sizeof(struct tcphdr);
257
258                         op = skb_header_pointer(skb,
259                                                 ptr + sizeof(struct tcphdr),
260                                                 optsize, _opt);
261                         if (op == NULL) {
262                                 sb_add(m, "OPT (TRUNCATED)");
263                                 return;
264                         }
265
266                         /* Max length: 127 "OPT (" 15*4*2chars ") " */
267                         sb_add(m, "OPT (");
268                         for (i =0; i < optsize; i++)
269                                 sb_add(m, "%02X", op[i]);
270                         sb_add(m, ") ");
271                 }
272                 break;
273         }
274         case IPPROTO_UDP:
275         case IPPROTO_UDPLITE: {
276                 struct udphdr _udph;
277                 const struct udphdr *uh;
278
279                 if (currenthdr == IPPROTO_UDP)
280                         /* Max length: 10 "PROTO=UDP "     */
281                         sb_add(m, "PROTO=UDP " );
282                 else    /* Max length: 14 "PROTO=UDPLITE " */
283                         sb_add(m, "PROTO=UDPLITE ");
284
285                 if (fragment)
286                         break;
287
288                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
289                 uh = skb_header_pointer(skb, ptr, sizeof(_udph), &_udph);
290                 if (uh == NULL) {
291                         sb_add(m, "INCOMPLETE [%u bytes] ", skb->len - ptr);
292                         return;
293                 }
294
295                 /* Max length: 20 "SPT=65535 DPT=65535 " */
296                 sb_add(m, "SPT=%u DPT=%u LEN=%u ",
297                        ntohs(uh->source), ntohs(uh->dest),
298                        ntohs(uh->len));
299                 break;
300         }
301         case IPPROTO_ICMPV6: {
302                 struct icmp6hdr _icmp6h;
303                 const struct icmp6hdr *ic;
304
305                 /* Max length: 13 "PROTO=ICMPv6 " */
306                 sb_add(m, "PROTO=ICMPv6 ");
307
308                 if (fragment)
309                         break;
310
311                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
312                 ic = skb_header_pointer(skb, ptr, sizeof(_icmp6h), &_icmp6h);
313                 if (ic == NULL) {
314                         sb_add(m, "INCOMPLETE [%u bytes] ", skb->len - ptr);
315                         return;
316                 }
317
318                 /* Max length: 18 "TYPE=255 CODE=255 " */
319                 sb_add(m, "TYPE=%u CODE=%u ", ic->icmp6_type, ic->icmp6_code);
320
321                 switch (ic->icmp6_type) {
322                 case ICMPV6_ECHO_REQUEST:
323                 case ICMPV6_ECHO_REPLY:
324                         /* Max length: 19 "ID=65535 SEQ=65535 " */
325                         sb_add(m, "ID=%u SEQ=%u ",
326                                 ntohs(ic->icmp6_identifier),
327                                 ntohs(ic->icmp6_sequence));
328                         break;
329                 case ICMPV6_MGM_QUERY:
330                 case ICMPV6_MGM_REPORT:
331                 case ICMPV6_MGM_REDUCTION:
332                         break;
333
334                 case ICMPV6_PARAMPROB:
335                         /* Max length: 17 "POINTER=ffffffff " */
336                         sb_add(m, "POINTER=%08x ", ntohl(ic->icmp6_pointer));
337                         /* Fall through */
338                 case ICMPV6_DEST_UNREACH:
339                 case ICMPV6_PKT_TOOBIG:
340                 case ICMPV6_TIME_EXCEED:
341                         /* Max length: 3+maxlen */
342                         if (recurse) {
343                                 sb_add(m, "[");
344                                 dump_packet(m, info, skb,
345                                             ptr + sizeof(_icmp6h), 0);
346                                 sb_add(m, "] ");
347                         }
348
349                         /* Max length: 10 "MTU=65535 " */
350                         if (ic->icmp6_type == ICMPV6_PKT_TOOBIG)
351                                 sb_add(m, "MTU=%u ", ntohl(ic->icmp6_mtu));
352                 }
353                 break;
354         }
355         /* Max length: 10 "PROTO=255 " */
356         default:
357                 sb_add(m, "PROTO=%u ", currenthdr);
358         }
359
360         /* Max length: 15 "UID=4294967295 " */
361         if ((logflags & IP6T_LOG_UID) && recurse && skb->sk) {
362                 read_lock_bh(&skb->sk->sk_callback_lock);
363                 if (skb->sk->sk_socket && skb->sk->sk_socket->file)
364                         sb_add(m, "UID=%u GID=%u ",
365                                 skb->sk->sk_socket->file->f_cred->fsuid,
366                                 skb->sk->sk_socket->file->f_cred->fsgid);
367                 read_unlock_bh(&skb->sk->sk_callback_lock);
368         }
369
370         /* Max length: 16 "MARK=0xFFFFFFFF " */
371         if (!recurse && skb->mark)
372                 sb_add(m, "MARK=0x%x ", skb->mark);
373 }
374
375 static void dump_mac_header(struct sbuff *m,
376                             const struct nf_loginfo *info,
377                             const struct sk_buff *skb)
378 {
379         struct net_device *dev = skb->dev;
380         unsigned int logflags = 0;
381
382         if (info->type == NF_LOG_TYPE_LOG)
383                 logflags = info->u.log.logflags;
384
385         if (!(logflags & IP6T_LOG_MACDECODE))
386                 goto fallback;
387
388         switch (dev->type) {
389         case ARPHRD_ETHER:
390                 sb_add(m, "MACSRC=%pM MACDST=%pM MACPROTO=%04x ",
391                        eth_hdr(skb)->h_source, eth_hdr(skb)->h_dest,
392                        ntohs(eth_hdr(skb)->h_proto));
393                 return;
394         default:
395                 break;
396         }
397
398 fallback:
399         sb_add(m, "MAC=");
400         if (dev->hard_header_len &&
401             skb->mac_header != skb->network_header) {
402                 const unsigned char *p = skb_mac_header(skb);
403                 unsigned int len = dev->hard_header_len;
404                 unsigned int i;
405
406                 if (dev->type == ARPHRD_SIT &&
407                     (p -= ETH_HLEN) < skb->head)
408                         p = NULL;
409
410                 if (p != NULL) {
411                         sb_add(m, "%02x", *p++);
412                         for (i = 1; i < len; i++)
413                                 sb_add(m, ":%02x", *p++);
414                 }
415                 sb_add(m, " ");
416
417                 if (dev->type == ARPHRD_SIT) {
418                         const struct iphdr *iph =
419                                 (struct iphdr *)skb_mac_header(skb);
420                         sb_add(m, "TUNNEL=%pI4->%pI4 ", &iph->saddr, &iph->daddr);
421                 }
422         } else
423                 sb_add(m, " ");
424 }
425
426 static struct nf_loginfo default_loginfo = {
427         .type   = NF_LOG_TYPE_LOG,
428         .u = {
429                 .log = {
430                         .level    = 5,
431                         .logflags = NF_LOG_MASK,
432                 },
433         },
434 };
435
436 static void
437 ip6t_log_packet(u_int8_t pf,
438                 unsigned int hooknum,
439                 const struct sk_buff *skb,
440                 const struct net_device *in,
441                 const struct net_device *out,
442                 const struct nf_loginfo *loginfo,
443                 const char *prefix)
444 {
445         struct sbuff *m = sb_open();
446
447         if (!loginfo)
448                 loginfo = &default_loginfo;
449
450         sb_add(m, "<%d>%sIN=%s OUT=%s ", loginfo->u.log.level,
451                prefix,
452                in ? in->name : "",
453                out ? out->name : "");
454
455         /* MAC logging for input path only. */
456         if (in && !out)
457                 dump_mac_header(m, loginfo, skb);
458
459         dump_packet(m, loginfo, skb, skb_network_offset(skb), 1);
460
461         sb_close(m);
462 }
463
464 static unsigned int
465 log_tg6(struct sk_buff *skb, const struct xt_action_param *par)
466 {
467         const struct ip6t_log_info *loginfo = par->targinfo;
468         struct nf_loginfo li;
469
470         li.type = NF_LOG_TYPE_LOG;
471         li.u.log.level = loginfo->level;
472         li.u.log.logflags = loginfo->logflags;
473
474         ip6t_log_packet(NFPROTO_IPV6, par->hooknum, skb, par->in, par->out,
475                         &li, loginfo->prefix);
476         return XT_CONTINUE;
477 }
478
479
480 static int log_tg6_check(const struct xt_tgchk_param *par)
481 {
482         const struct ip6t_log_info *loginfo = par->targinfo;
483
484         if (loginfo->level >= 8) {
485                 pr_debug("level %u >= 8\n", loginfo->level);
486                 return -EINVAL;
487         }
488         if (loginfo->prefix[sizeof(loginfo->prefix)-1] != '\0') {
489                 pr_debug("prefix not null-terminated\n");
490                 return -EINVAL;
491         }
492         return 0;
493 }
494
495 static struct xt_target log_tg6_reg __read_mostly = {
496         .name           = "LOG",
497         .family         = NFPROTO_IPV6,
498         .target         = log_tg6,
499         .targetsize     = sizeof(struct ip6t_log_info),
500         .checkentry     = log_tg6_check,
501         .me             = THIS_MODULE,
502 };
503
504 static struct nf_logger ip6t_logger __read_mostly = {
505         .name           = "ip6t_LOG",
506         .logfn          = &ip6t_log_packet,
507         .me             = THIS_MODULE,
508 };
509
510 static int __init log_tg6_init(void)
511 {
512         int ret;
513
514         ret = xt_register_target(&log_tg6_reg);
515         if (ret < 0)
516                 return ret;
517         nf_log_register(NFPROTO_IPV6, &ip6t_logger);
518         return 0;
519 }
520
521 static void __exit log_tg6_exit(void)
522 {
523         nf_log_unregister(&ip6t_logger);
524         xt_unregister_target(&log_tg6_reg);
525 }
526
527 module_init(log_tg6_init);
528 module_exit(log_tg6_exit);