30fc21d6165a6bbf3e20bb6f8c69eb207d68a23e
[linux-2.6.git] / net / ipv4 / netfilter / ip_conntrack_proto_icmp.c
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 #include <linux/types.h>
10 #include <linux/sched.h>
11 #include <linux/timer.h>
12 #include <linux/netfilter.h>
13 #include <linux/in.h>
14 #include <linux/icmp.h>
15 #include <linux/seq_file.h>
16 #include <linux/skbuff.h>
17 #include <net/ip.h>
18 #include <net/checksum.h>
19 #include <linux/netfilter.h>
20 #include <linux/netfilter_ipv4.h>
21 #include <linux/netfilter_ipv4/ip_conntrack.h>
22 #include <linux/netfilter_ipv4/ip_conntrack_core.h>
23 #include <linux/netfilter_ipv4/ip_conntrack_protocol.h>
24
25 unsigned long ip_ct_icmp_timeout = 30*HZ;
26
27 #if 0
28 #define DEBUGP printk
29 #else
30 #define DEBUGP(format, args...)
31 #endif
32
33 static int icmp_pkt_to_tuple(const struct sk_buff *skb,
34                              unsigned int dataoff,
35                              struct ip_conntrack_tuple *tuple)
36 {
37         struct icmphdr _hdr, *hp;
38
39         hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
40         if (hp == NULL)
41                 return 0;
42
43         tuple->dst.u.icmp.type = hp->type;
44         tuple->src.u.icmp.id = hp->un.echo.id;
45         tuple->dst.u.icmp.code = hp->code;
46
47         return 1;
48 }
49
50 /* Add 1; spaces filled with 0. */
51 static const u_int8_t invmap[] = {
52         [ICMP_ECHO] = ICMP_ECHOREPLY + 1,
53         [ICMP_ECHOREPLY] = ICMP_ECHO + 1,
54         [ICMP_TIMESTAMP] = ICMP_TIMESTAMPREPLY + 1,
55         [ICMP_TIMESTAMPREPLY] = ICMP_TIMESTAMP + 1,
56         [ICMP_INFO_REQUEST] = ICMP_INFO_REPLY + 1,
57         [ICMP_INFO_REPLY] = ICMP_INFO_REQUEST + 1,
58         [ICMP_ADDRESS] = ICMP_ADDRESSREPLY + 1,
59         [ICMP_ADDRESSREPLY] = ICMP_ADDRESS + 1
60 };
61
62 static int icmp_invert_tuple(struct ip_conntrack_tuple *tuple,
63                              const struct ip_conntrack_tuple *orig)
64 {
65         if (orig->dst.u.icmp.type >= sizeof(invmap)
66             || !invmap[orig->dst.u.icmp.type])
67                 return 0;
68
69         tuple->src.u.icmp.id = orig->src.u.icmp.id;
70         tuple->dst.u.icmp.type = invmap[orig->dst.u.icmp.type] - 1;
71         tuple->dst.u.icmp.code = orig->dst.u.icmp.code;
72         return 1;
73 }
74
75 /* Print out the per-protocol part of the tuple. */
76 static int icmp_print_tuple(struct seq_file *s,
77                             const struct ip_conntrack_tuple *tuple)
78 {
79         return seq_printf(s, "type=%u code=%u id=%u ",
80                           tuple->dst.u.icmp.type,
81                           tuple->dst.u.icmp.code,
82                           ntohs(tuple->src.u.icmp.id));
83 }
84
85 /* Print out the private part of the conntrack. */
86 static int icmp_print_conntrack(struct seq_file *s,
87                                 const struct ip_conntrack *conntrack)
88 {
89         return 0;
90 }
91
92 /* Returns verdict for packet, or -1 for invalid. */
93 static int icmp_packet(struct ip_conntrack *ct,
94                        const struct sk_buff *skb,
95                        enum ip_conntrack_info ctinfo)
96 {
97         /* Try to delete connection immediately after all replies:
98            won't actually vanish as we still have skb, and del_timer
99            means this will only run once even if count hits zero twice
100            (theoretically possible with SMP) */
101         if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
102                 if (atomic_dec_and_test(&ct->proto.icmp.count)
103                     && del_timer(&ct->timeout))
104                         ct->timeout.function((unsigned long)ct);
105         } else {
106                 atomic_inc(&ct->proto.icmp.count);
107                 ip_conntrack_event_cache(IPCT_PROTOINFO_VOLATILE, skb);
108                 ip_ct_refresh_acct(ct, ctinfo, skb, ip_ct_icmp_timeout);
109         }
110
111         return NF_ACCEPT;
112 }
113
114 /* Called when a new connection for this protocol found. */
115 static int icmp_new(struct ip_conntrack *conntrack,
116                     const struct sk_buff *skb)
117 {
118         static const u_int8_t valid_new[] = { 
119                 [ICMP_ECHO] = 1,
120                 [ICMP_TIMESTAMP] = 1,
121                 [ICMP_INFO_REQUEST] = 1,
122                 [ICMP_ADDRESS] = 1 
123         };
124
125         if (conntrack->tuplehash[0].tuple.dst.u.icmp.type >= sizeof(valid_new)
126             || !valid_new[conntrack->tuplehash[0].tuple.dst.u.icmp.type]) {
127                 /* Can't create a new ICMP `conn' with this. */
128                 DEBUGP("icmp: can't create new conn with type %u\n",
129                        conntrack->tuplehash[0].tuple.dst.u.icmp.type);
130                 DUMP_TUPLE(&conntrack->tuplehash[0].tuple);
131                 return 0;
132         }
133         atomic_set(&conntrack->proto.icmp.count, 0);
134         return 1;
135 }
136
137 static int
138 icmp_error_message(struct sk_buff *skb,
139                    enum ip_conntrack_info *ctinfo,
140                    unsigned int hooknum)
141 {
142         struct ip_conntrack_tuple innertuple, origtuple;
143         struct {
144                 struct icmphdr icmp;
145                 struct iphdr ip;
146         } _in, *inside;
147         struct ip_conntrack_protocol *innerproto;
148         struct ip_conntrack_tuple_hash *h;
149         int dataoff;
150
151         IP_NF_ASSERT(skb->nfct == NULL);
152
153         /* Not enough header? */
154         inside = skb_header_pointer(skb, skb->nh.iph->ihl*4, sizeof(_in), &_in);
155         if (inside == NULL)
156                 return -NF_ACCEPT;
157
158         /* Ignore ICMP's containing fragments (shouldn't happen) */
159         if (inside->ip.frag_off & htons(IP_OFFSET)) {
160                 DEBUGP("icmp_error_track: fragment of proto %u\n",
161                        inside->ip.protocol);
162                 return -NF_ACCEPT;
163         }
164
165         innerproto = ip_conntrack_proto_find_get(inside->ip.protocol);
166         dataoff = skb->nh.iph->ihl*4 + sizeof(inside->icmp) + inside->ip.ihl*4;
167         /* Are they talking about one of our connections? */
168         if (!ip_ct_get_tuple(&inside->ip, skb, dataoff, &origtuple, innerproto)) {
169                 DEBUGP("icmp_error: ! get_tuple p=%u", inside->ip.protocol);
170                 ip_conntrack_proto_put(innerproto);
171                 return -NF_ACCEPT;
172         }
173
174         /* Ordinarily, we'd expect the inverted tupleproto, but it's
175            been preserved inside the ICMP. */
176         if (!ip_ct_invert_tuple(&innertuple, &origtuple, innerproto)) {
177                 DEBUGP("icmp_error_track: Can't invert tuple\n");
178                 ip_conntrack_proto_put(innerproto);
179                 return -NF_ACCEPT;
180         }
181         ip_conntrack_proto_put(innerproto);
182
183         *ctinfo = IP_CT_RELATED;
184
185         h = ip_conntrack_find_get(&innertuple, NULL);
186         if (!h) {
187                 /* Locally generated ICMPs will match inverted if they
188                    haven't been SNAT'ed yet */
189                 /* FIXME: NAT code has to handle half-done double NAT --RR */
190                 if (hooknum == NF_IP_LOCAL_OUT)
191                         h = ip_conntrack_find_get(&origtuple, NULL);
192
193                 if (!h) {
194                         DEBUGP("icmp_error_track: no match\n");
195                         return -NF_ACCEPT;
196                 }
197                 /* Reverse direction from that found */
198                 if (DIRECTION(h) != IP_CT_DIR_REPLY)
199                         *ctinfo += IP_CT_IS_REPLY;
200         } else {
201                 if (DIRECTION(h) == IP_CT_DIR_REPLY)
202                         *ctinfo += IP_CT_IS_REPLY;
203         }
204
205         /* Update skb to refer to this connection */
206         skb->nfct = &tuplehash_to_ctrack(h)->ct_general;
207         skb->nfctinfo = *ctinfo;
208         return -NF_ACCEPT;
209 }
210
211 /* Small and modified version of icmp_rcv */
212 static int
213 icmp_error(struct sk_buff *skb, enum ip_conntrack_info *ctinfo,
214            unsigned int hooknum)
215 {
216         struct icmphdr _ih, *icmph;
217
218         /* Not enough header? */
219         icmph = skb_header_pointer(skb, skb->nh.iph->ihl*4, sizeof(_ih), &_ih);
220         if (icmph == NULL) {
221                 if (LOG_INVALID(IPPROTO_ICMP))
222                         nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
223                                       "ip_ct_icmp: short packet ");
224                 return -NF_ACCEPT;
225         }
226
227         /* See ip_conntrack_proto_tcp.c */
228         if (hooknum != NF_IP_PRE_ROUTING)
229                 goto checksum_skipped;
230
231         switch (skb->ip_summed) {
232         case CHECKSUM_HW:
233                 if (!(u16)csum_fold(skb->csum)) 
234                         break;
235                 /* fall through */
236         case CHECKSUM_NONE:
237                 skb->csum = 0;
238                 if (__skb_checksum_complete(skb)) {
239                         if (LOG_INVALID(IPPROTO_ICMP))
240                                 nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
241                                               "ip_ct_icmp: bad ICMP checksum ");
242                         return -NF_ACCEPT;
243                 }
244         }
245
246 checksum_skipped:
247         /*
248          *      18 is the highest 'known' ICMP type. Anything else is a mystery
249          *
250          *      RFC 1122: 3.2.2  Unknown ICMP messages types MUST be silently
251          *                discarded.
252          */
253         if (icmph->type > NR_ICMP_TYPES) {
254                 if (LOG_INVALID(IPPROTO_ICMP))
255                         nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
256                                       "ip_ct_icmp: invalid ICMP type ");
257                 return -NF_ACCEPT;
258         }
259
260         /* Need to track icmp error message? */
261         if (icmph->type != ICMP_DEST_UNREACH
262             && icmph->type != ICMP_SOURCE_QUENCH
263             && icmph->type != ICMP_TIME_EXCEEDED
264             && icmph->type != ICMP_PARAMETERPROB
265             && icmph->type != ICMP_REDIRECT)
266                 return NF_ACCEPT;
267
268         return icmp_error_message(skb, ctinfo, hooknum);
269 }
270
271 #if defined(CONFIG_IP_NF_CONNTRACK_NETLINK) || \
272     defined(CONFIG_IP_NF_CONNTRACK_NETLINK_MODULE)
273 static int icmp_tuple_to_nfattr(struct sk_buff *skb,
274                                 const struct ip_conntrack_tuple *t)
275 {
276         NFA_PUT(skb, CTA_PROTO_ICMP_ID, sizeof(u_int16_t),
277                 &t->src.u.icmp.id);
278         NFA_PUT(skb, CTA_PROTO_ICMP_TYPE, sizeof(u_int8_t),
279                 &t->dst.u.icmp.type);
280         NFA_PUT(skb, CTA_PROTO_ICMP_CODE, sizeof(u_int8_t),
281                 &t->dst.u.icmp.code);
282
283         return 0;
284
285 nfattr_failure:
286         return -1;
287 }
288
289 static int icmp_nfattr_to_tuple(struct nfattr *tb[],
290                                 struct ip_conntrack_tuple *tuple)
291 {
292         if (!tb[CTA_PROTO_ICMP_TYPE-1]
293             || !tb[CTA_PROTO_ICMP_CODE-1]
294             || !tb[CTA_PROTO_ICMP_ID-1])
295                 return -EINVAL;
296
297         tuple->dst.u.icmp.type = 
298                         *(u_int8_t *)NFA_DATA(tb[CTA_PROTO_ICMP_TYPE-1]);
299         tuple->dst.u.icmp.code =
300                         *(u_int8_t *)NFA_DATA(tb[CTA_PROTO_ICMP_CODE-1]);
301         tuple->src.u.icmp.id =
302                         *(u_int16_t *)NFA_DATA(tb[CTA_PROTO_ICMP_ID-1]);
303
304         if (tuple->dst.u.icmp.type >= sizeof(invmap)
305             || !invmap[tuple->dst.u.icmp.type])
306                 return -EINVAL;
307
308         return 0;
309 }
310 #endif
311
312 struct ip_conntrack_protocol ip_conntrack_protocol_icmp =
313 {
314         .proto                  = IPPROTO_ICMP,
315         .name                   = "icmp",
316         .pkt_to_tuple           = icmp_pkt_to_tuple,
317         .invert_tuple           = icmp_invert_tuple,
318         .print_tuple            = icmp_print_tuple,
319         .print_conntrack        = icmp_print_conntrack,
320         .packet                 = icmp_packet,
321         .new                    = icmp_new,
322         .error                  = icmp_error,
323 #if defined(CONFIG_IP_NF_CONNTRACK_NETLINK) || \
324     defined(CONFIG_IP_NF_CONNTRACK_NETLINK_MODULE)
325         .tuple_to_nfattr        = icmp_tuple_to_nfattr,
326         .nfattr_to_tuple        = icmp_nfattr_to_tuple,
327 #endif
328 };