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Linux/net/ipv4/netfilter/nf_log_ipv4.c

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  1 /* (C) 1999-2001 Paul `Rusty' Russell
  2  * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
  3  *
  4  * This program is free software; you can redistribute it and/or modify
  5  * it under the terms of the GNU General Public License version 2 as
  6  * published by the Free Software Foundation.
  7  */
  8 
  9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 10 
 11 #include <linux/kernel.h>
 12 #include <linux/module.h>
 13 #include <linux/spinlock.h>
 14 #include <linux/skbuff.h>
 15 #include <linux/if_arp.h>
 16 #include <linux/ip.h>
 17 #include <net/ipv6.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/xt_LOG.h>
 25 #include <net/netfilter/nf_log.h>
 26 
 27 static struct nf_loginfo default_loginfo = {
 28         .type   = NF_LOG_TYPE_LOG,
 29         .u = {
 30                 .log = {
 31                         .level    = LOGLEVEL_NOTICE,
 32                         .logflags = NF_LOG_MASK,
 33                 },
 34         },
 35 };
 36 
 37 /* One level of recursion won't kill us */
 38 static void dump_ipv4_packet(struct nf_log_buf *m,
 39                              const struct nf_loginfo *info,
 40                              const struct sk_buff *skb, unsigned int iphoff)
 41 {
 42         struct iphdr _iph;
 43         const struct iphdr *ih;
 44         unsigned int logflags;
 45 
 46         if (info->type == NF_LOG_TYPE_LOG)
 47                 logflags = info->u.log.logflags;
 48         else
 49                 logflags = NF_LOG_MASK;
 50 
 51         ih = skb_header_pointer(skb, iphoff, sizeof(_iph), &_iph);
 52         if (ih == NULL) {
 53                 nf_log_buf_add(m, "TRUNCATED");
 54                 return;
 55         }
 56 
 57         /* Important fields:
 58          * TOS, len, DF/MF, fragment offset, TTL, src, dst, options. */
 59         /* Max length: 40 "SRC=255.255.255.255 DST=255.255.255.255 " */
 60         nf_log_buf_add(m, "SRC=%pI4 DST=%pI4 ", &ih->saddr, &ih->daddr);
 61 
 62         /* Max length: 46 "LEN=65535 TOS=0xFF PREC=0xFF TTL=255 ID=65535 " */
 63         nf_log_buf_add(m, "LEN=%u TOS=0x%02X PREC=0x%02X TTL=%u ID=%u ",
 64                        ntohs(ih->tot_len), ih->tos & IPTOS_TOS_MASK,
 65                        ih->tos & IPTOS_PREC_MASK, ih->ttl, ntohs(ih->id));
 66 
 67         /* Max length: 6 "CE DF MF " */
 68         if (ntohs(ih->frag_off) & IP_CE)
 69                 nf_log_buf_add(m, "CE ");
 70         if (ntohs(ih->frag_off) & IP_DF)
 71                 nf_log_buf_add(m, "DF ");
 72         if (ntohs(ih->frag_off) & IP_MF)
 73                 nf_log_buf_add(m, "MF ");
 74 
 75         /* Max length: 11 "FRAG:65535 " */
 76         if (ntohs(ih->frag_off) & IP_OFFSET)
 77                 nf_log_buf_add(m, "FRAG:%u ", ntohs(ih->frag_off) & IP_OFFSET);
 78 
 79         if ((logflags & XT_LOG_IPOPT) &&
 80             ih->ihl * 4 > sizeof(struct iphdr)) {
 81                 const unsigned char *op;
 82                 unsigned char _opt[4 * 15 - sizeof(struct iphdr)];
 83                 unsigned int i, optsize;
 84 
 85                 optsize = ih->ihl * 4 - sizeof(struct iphdr);
 86                 op = skb_header_pointer(skb, iphoff+sizeof(_iph),
 87                                         optsize, _opt);
 88                 if (op == NULL) {
 89                         nf_log_buf_add(m, "TRUNCATED");
 90                         return;
 91                 }
 92 
 93                 /* Max length: 127 "OPT (" 15*4*2chars ") " */
 94                 nf_log_buf_add(m, "OPT (");
 95                 for (i = 0; i < optsize; i++)
 96                         nf_log_buf_add(m, "%02X", op[i]);
 97                 nf_log_buf_add(m, ") ");
 98         }
 99 
100         switch (ih->protocol) {
101         case IPPROTO_TCP:
102                 if (nf_log_dump_tcp_header(m, skb, ih->protocol,
103                                            ntohs(ih->frag_off) & IP_OFFSET,
104                                            iphoff+ih->ihl*4, logflags))
105                         return;
106                 break;
107         case IPPROTO_UDP:
108         case IPPROTO_UDPLITE:
109                 if (nf_log_dump_udp_header(m, skb, ih->protocol,
110                                            ntohs(ih->frag_off) & IP_OFFSET,
111                                            iphoff+ih->ihl*4))
112                         return;
113                 break;
114         case IPPROTO_ICMP: {
115                 struct icmphdr _icmph;
116                 const struct icmphdr *ich;
117                 static const size_t required_len[NR_ICMP_TYPES+1]
118                         = { [ICMP_ECHOREPLY] = 4,
119                             [ICMP_DEST_UNREACH]
120                             = 8 + sizeof(struct iphdr),
121                             [ICMP_SOURCE_QUENCH]
122                             = 8 + sizeof(struct iphdr),
123                             [ICMP_REDIRECT]
124                             = 8 + sizeof(struct iphdr),
125                             [ICMP_ECHO] = 4,
126                             [ICMP_TIME_EXCEEDED]
127                             = 8 + sizeof(struct iphdr),
128                             [ICMP_PARAMETERPROB]
129                             = 8 + sizeof(struct iphdr),
130                             [ICMP_TIMESTAMP] = 20,
131                             [ICMP_TIMESTAMPREPLY] = 20,
132                             [ICMP_ADDRESS] = 12,
133                             [ICMP_ADDRESSREPLY] = 12 };
134 
135                 /* Max length: 11 "PROTO=ICMP " */
136                 nf_log_buf_add(m, "PROTO=ICMP ");
137 
138                 if (ntohs(ih->frag_off) & IP_OFFSET)
139                         break;
140 
141                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
142                 ich = skb_header_pointer(skb, iphoff + ih->ihl * 4,
143                                          sizeof(_icmph), &_icmph);
144                 if (ich == NULL) {
145                         nf_log_buf_add(m, "INCOMPLETE [%u bytes] ",
146                                        skb->len - iphoff - ih->ihl*4);
147                         break;
148                 }
149 
150                 /* Max length: 18 "TYPE=255 CODE=255 " */
151                 nf_log_buf_add(m, "TYPE=%u CODE=%u ", ich->type, ich->code);
152 
153                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
154                 if (ich->type <= NR_ICMP_TYPES &&
155                     required_len[ich->type] &&
156                     skb->len-iphoff-ih->ihl*4 < required_len[ich->type]) {
157                         nf_log_buf_add(m, "INCOMPLETE [%u bytes] ",
158                                        skb->len - iphoff - ih->ihl*4);
159                         break;
160                 }
161 
162                 switch (ich->type) {
163                 case ICMP_ECHOREPLY:
164                 case ICMP_ECHO:
165                         /* Max length: 19 "ID=65535 SEQ=65535 " */
166                         nf_log_buf_add(m, "ID=%u SEQ=%u ",
167                                        ntohs(ich->un.echo.id),
168                                        ntohs(ich->un.echo.sequence));
169                         break;
170 
171                 case ICMP_PARAMETERPROB:
172                         /* Max length: 14 "PARAMETER=255 " */
173                         nf_log_buf_add(m, "PARAMETER=%u ",
174                                        ntohl(ich->un.gateway) >> 24);
175                         break;
176                 case ICMP_REDIRECT:
177                         /* Max length: 24 "GATEWAY=255.255.255.255 " */
178                         nf_log_buf_add(m, "GATEWAY=%pI4 ", &ich->un.gateway);
179                         /* Fall through */
180                 case ICMP_DEST_UNREACH:
181                 case ICMP_SOURCE_QUENCH:
182                 case ICMP_TIME_EXCEEDED:
183                         /* Max length: 3+maxlen */
184                         if (!iphoff) { /* Only recurse once. */
185                                 nf_log_buf_add(m, "[");
186                                 dump_ipv4_packet(m, info, skb,
187                                             iphoff + ih->ihl*4+sizeof(_icmph));
188                                 nf_log_buf_add(m, "] ");
189                         }
190 
191                         /* Max length: 10 "MTU=65535 " */
192                         if (ich->type == ICMP_DEST_UNREACH &&
193                             ich->code == ICMP_FRAG_NEEDED) {
194                                 nf_log_buf_add(m, "MTU=%u ",
195                                                ntohs(ich->un.frag.mtu));
196                         }
197                 }
198                 break;
199         }
200         /* Max Length */
201         case IPPROTO_AH: {
202                 struct ip_auth_hdr _ahdr;
203                 const struct ip_auth_hdr *ah;
204 
205                 if (ntohs(ih->frag_off) & IP_OFFSET)
206                         break;
207 
208                 /* Max length: 9 "PROTO=AH " */
209                 nf_log_buf_add(m, "PROTO=AH ");
210 
211                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
212                 ah = skb_header_pointer(skb, iphoff+ih->ihl*4,
213                                         sizeof(_ahdr), &_ahdr);
214                 if (ah == NULL) {
215                         nf_log_buf_add(m, "INCOMPLETE [%u bytes] ",
216                                        skb->len - iphoff - ih->ihl*4);
217                         break;
218                 }
219 
220                 /* Length: 15 "SPI=0xF1234567 " */
221                 nf_log_buf_add(m, "SPI=0x%x ", ntohl(ah->spi));
222                 break;
223         }
224         case IPPROTO_ESP: {
225                 struct ip_esp_hdr _esph;
226                 const struct ip_esp_hdr *eh;
227 
228                 /* Max length: 10 "PROTO=ESP " */
229                 nf_log_buf_add(m, "PROTO=ESP ");
230 
231                 if (ntohs(ih->frag_off) & IP_OFFSET)
232                         break;
233 
234                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
235                 eh = skb_header_pointer(skb, iphoff+ih->ihl*4,
236                                         sizeof(_esph), &_esph);
237                 if (eh == NULL) {
238                         nf_log_buf_add(m, "INCOMPLETE [%u bytes] ",
239                                        skb->len - iphoff - ih->ihl*4);
240                         break;
241                 }
242 
243                 /* Length: 15 "SPI=0xF1234567 " */
244                 nf_log_buf_add(m, "SPI=0x%x ", ntohl(eh->spi));
245                 break;
246         }
247         /* Max length: 10 "PROTO 255 " */
248         default:
249                 nf_log_buf_add(m, "PROTO=%u ", ih->protocol);
250         }
251 
252         /* Max length: 15 "UID=4294967295 " */
253         if ((logflags & XT_LOG_UID) && !iphoff)
254                 nf_log_dump_sk_uid_gid(m, skb->sk);
255 
256         /* Max length: 16 "MARK=0xFFFFFFFF " */
257         if (!iphoff && skb->mark)
258                 nf_log_buf_add(m, "MARK=0x%x ", skb->mark);
259 
260         /* Proto    Max log string length */
261         /* IP:      40+46+6+11+127 = 230 */
262         /* TCP:     10+max(25,20+30+13+9+32+11+127) = 252 */
263         /* UDP:     10+max(25,20) = 35 */
264         /* UDPLITE: 14+max(25,20) = 39 */
265         /* ICMP:    11+max(25, 18+25+max(19,14,24+3+n+10,3+n+10)) = 91+n */
266         /* ESP:     10+max(25)+15 = 50 */
267         /* AH:      9+max(25)+15 = 49 */
268         /* unknown: 10 */
269 
270         /* (ICMP allows recursion one level deep) */
271         /* maxlen =  IP + ICMP +  IP + max(TCP,UDP,ICMP,unknown) */
272         /* maxlen = 230+   91  + 230 + 252 = 803 */
273 }
274 
275 static void dump_ipv4_mac_header(struct nf_log_buf *m,
276                             const struct nf_loginfo *info,
277                             const struct sk_buff *skb)
278 {
279         struct net_device *dev = skb->dev;
280         unsigned int logflags = 0;
281 
282         if (info->type == NF_LOG_TYPE_LOG)
283                 logflags = info->u.log.logflags;
284 
285         if (!(logflags & XT_LOG_MACDECODE))
286                 goto fallback;
287 
288         switch (dev->type) {
289         case ARPHRD_ETHER:
290                 nf_log_buf_add(m, "MACSRC=%pM MACDST=%pM MACPROTO=%04x ",
291                                eth_hdr(skb)->h_source, eth_hdr(skb)->h_dest,
292                                ntohs(eth_hdr(skb)->h_proto));
293                 return;
294         default:
295                 break;
296         }
297 
298 fallback:
299         nf_log_buf_add(m, "MAC=");
300         if (dev->hard_header_len &&
301             skb->mac_header != skb->network_header) {
302                 const unsigned char *p = skb_mac_header(skb);
303                 unsigned int i;
304 
305                 nf_log_buf_add(m, "%02x", *p++);
306                 for (i = 1; i < dev->hard_header_len; i++, p++)
307                         nf_log_buf_add(m, ":%02x", *p);
308         }
309         nf_log_buf_add(m, " ");
310 }
311 
312 static void nf_log_ip_packet(struct net *net, u_int8_t pf,
313                              unsigned int hooknum, const struct sk_buff *skb,
314                              const struct net_device *in,
315                              const struct net_device *out,
316                              const struct nf_loginfo *loginfo,
317                              const char *prefix)
318 {
319         struct nf_log_buf *m;
320 
321         /* FIXME: Disabled from containers until syslog ns is supported */
322         if (!net_eq(net, &init_net))
323                 return;
324 
325         m = nf_log_buf_open();
326 
327         if (!loginfo)
328                 loginfo = &default_loginfo;
329 
330         nf_log_dump_packet_common(m, pf, hooknum, skb, in,
331                                   out, loginfo, prefix);
332 
333         if (in != NULL)
334                 dump_ipv4_mac_header(m, loginfo, skb);
335 
336         dump_ipv4_packet(m, loginfo, skb, 0);
337 
338         nf_log_buf_close(m);
339 }
340 
341 static struct nf_logger nf_ip_logger __read_mostly = {
342         .name           = "nf_log_ipv4",
343         .type           = NF_LOG_TYPE_LOG,
344         .logfn          = nf_log_ip_packet,
345         .me             = THIS_MODULE,
346 };
347 
348 static int __net_init nf_log_ipv4_net_init(struct net *net)
349 {
350         nf_log_set(net, NFPROTO_IPV4, &nf_ip_logger);
351         return 0;
352 }
353 
354 static void __net_exit nf_log_ipv4_net_exit(struct net *net)
355 {
356         nf_log_unset(net, &nf_ip_logger);
357 }
358 
359 static struct pernet_operations nf_log_ipv4_net_ops = {
360         .init = nf_log_ipv4_net_init,
361         .exit = nf_log_ipv4_net_exit,
362 };
363 
364 static int __init nf_log_ipv4_init(void)
365 {
366         int ret;
367 
368         ret = register_pernet_subsys(&nf_log_ipv4_net_ops);
369         if (ret < 0)
370                 return ret;
371 
372         ret = nf_log_register(NFPROTO_IPV4, &nf_ip_logger);
373         if (ret < 0) {
374                 pr_err("failed to register logger\n");
375                 goto err1;
376         }
377 
378         return 0;
379 
380 err1:
381         unregister_pernet_subsys(&nf_log_ipv4_net_ops);
382         return ret;
383 }
384 
385 static void __exit nf_log_ipv4_exit(void)
386 {
387         unregister_pernet_subsys(&nf_log_ipv4_net_ops);
388         nf_log_unregister(&nf_ip_logger);
389 }
390 
391 module_init(nf_log_ipv4_init);
392 module_exit(nf_log_ipv4_exit);
393 
394 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
395 MODULE_DESCRIPTION("Netfilter IPv4 packet logging");
396 MODULE_LICENSE("GPL");
397 MODULE_ALIAS_NF_LOGGER(AF_INET, 0);
398 

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