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1da177e4 LT |
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> | |
fb286bb2 | 16 | #include <linux/skbuff.h> |
1da177e4 LT |
17 | #include <net/ip.h> |
18 | #include <net/checksum.h> | |
1da177e4 LT |
19 | #include <linux/netfilter_ipv4.h> |
20 | #include <linux/netfilter_ipv4/ip_conntrack.h> | |
21 | #include <linux/netfilter_ipv4/ip_conntrack_core.h> | |
22 | #include <linux/netfilter_ipv4/ip_conntrack_protocol.h> | |
23 | ||
94aec08e | 24 | unsigned int ip_ct_icmp_timeout __read_mostly = 30*HZ; |
1da177e4 LT |
25 | |
26 | #if 0 | |
27 | #define DEBUGP printk | |
28 | #else | |
29 | #define DEBUGP(format, args...) | |
30 | #endif | |
31 | ||
32 | static int icmp_pkt_to_tuple(const struct sk_buff *skb, | |
33 | unsigned int dataoff, | |
34 | struct ip_conntrack_tuple *tuple) | |
35 | { | |
36 | struct icmphdr _hdr, *hp; | |
37 | ||
38 | hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr); | |
39 | if (hp == NULL) | |
40 | return 0; | |
41 | ||
42 | tuple->dst.u.icmp.type = hp->type; | |
43 | tuple->src.u.icmp.id = hp->un.echo.id; | |
44 | tuple->dst.u.icmp.code = hp->code; | |
45 | ||
46 | return 1; | |
47 | } | |
48 | ||
90c4656e YK |
49 | /* Add 1; spaces filled with 0. */ |
50 | static const u_int8_t invmap[] = { | |
51 | [ICMP_ECHO] = ICMP_ECHOREPLY + 1, | |
52 | [ICMP_ECHOREPLY] = ICMP_ECHO + 1, | |
53 | [ICMP_TIMESTAMP] = ICMP_TIMESTAMPREPLY + 1, | |
54 | [ICMP_TIMESTAMPREPLY] = ICMP_TIMESTAMP + 1, | |
55 | [ICMP_INFO_REQUEST] = ICMP_INFO_REPLY + 1, | |
56 | [ICMP_INFO_REPLY] = ICMP_INFO_REQUEST + 1, | |
57 | [ICMP_ADDRESS] = ICMP_ADDRESSREPLY + 1, | |
58 | [ICMP_ADDRESSREPLY] = ICMP_ADDRESS + 1 | |
59 | }; | |
60 | ||
1da177e4 LT |
61 | static int icmp_invert_tuple(struct ip_conntrack_tuple *tuple, |
62 | const struct ip_conntrack_tuple *orig) | |
63 | { | |
1da177e4 LT |
64 | if (orig->dst.u.icmp.type >= sizeof(invmap) |
65 | || !invmap[orig->dst.u.icmp.type]) | |
66 | return 0; | |
67 | ||
68 | tuple->src.u.icmp.id = orig->src.u.icmp.id; | |
69 | tuple->dst.u.icmp.type = invmap[orig->dst.u.icmp.type] - 1; | |
70 | tuple->dst.u.icmp.code = orig->dst.u.icmp.code; | |
71 | return 1; | |
72 | } | |
73 | ||
74 | /* Print out the per-protocol part of the tuple. */ | |
75 | static int icmp_print_tuple(struct seq_file *s, | |
76 | const struct ip_conntrack_tuple *tuple) | |
77 | { | |
78 | return seq_printf(s, "type=%u code=%u id=%u ", | |
79 | tuple->dst.u.icmp.type, | |
80 | tuple->dst.u.icmp.code, | |
81 | ntohs(tuple->src.u.icmp.id)); | |
82 | } | |
83 | ||
84 | /* Print out the private part of the conntrack. */ | |
85 | static int icmp_print_conntrack(struct seq_file *s, | |
86 | const struct ip_conntrack *conntrack) | |
87 | { | |
88 | return 0; | |
89 | } | |
90 | ||
91 | /* Returns verdict for packet, or -1 for invalid. */ | |
92 | static int icmp_packet(struct ip_conntrack *ct, | |
93 | const struct sk_buff *skb, | |
94 | enum ip_conntrack_info ctinfo) | |
95 | { | |
96 | /* Try to delete connection immediately after all replies: | |
97 | won't actually vanish as we still have skb, and del_timer | |
98 | means this will only run once even if count hits zero twice | |
99 | (theoretically possible with SMP) */ | |
100 | if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) { | |
101 | if (atomic_dec_and_test(&ct->proto.icmp.count) | |
102 | && del_timer(&ct->timeout)) | |
103 | ct->timeout.function((unsigned long)ct); | |
104 | } else { | |
105 | atomic_inc(&ct->proto.icmp.count); | |
ac3247ba | 106 | ip_conntrack_event_cache(IPCT_PROTOINFO_VOLATILE, skb); |
1da177e4 LT |
107 | ip_ct_refresh_acct(ct, ctinfo, skb, ip_ct_icmp_timeout); |
108 | } | |
109 | ||
110 | return NF_ACCEPT; | |
111 | } | |
112 | ||
113 | /* Called when a new connection for this protocol found. */ | |
114 | static int icmp_new(struct ip_conntrack *conntrack, | |
115 | const struct sk_buff *skb) | |
116 | { | |
90c4656e YK |
117 | static const u_int8_t valid_new[] = { |
118 | [ICMP_ECHO] = 1, | |
119 | [ICMP_TIMESTAMP] = 1, | |
120 | [ICMP_INFO_REQUEST] = 1, | |
121 | [ICMP_ADDRESS] = 1 | |
122 | }; | |
123 | ||
1da177e4 LT |
124 | if (conntrack->tuplehash[0].tuple.dst.u.icmp.type >= sizeof(valid_new) |
125 | || !valid_new[conntrack->tuplehash[0].tuple.dst.u.icmp.type]) { | |
126 | /* Can't create a new ICMP `conn' with this. */ | |
127 | DEBUGP("icmp: can't create new conn with type %u\n", | |
128 | conntrack->tuplehash[0].tuple.dst.u.icmp.type); | |
129 | DUMP_TUPLE(&conntrack->tuplehash[0].tuple); | |
130 | return 0; | |
131 | } | |
132 | atomic_set(&conntrack->proto.icmp.count, 0); | |
133 | return 1; | |
134 | } | |
135 | ||
136 | static int | |
137 | icmp_error_message(struct sk_buff *skb, | |
138 | enum ip_conntrack_info *ctinfo, | |
139 | unsigned int hooknum) | |
140 | { | |
141 | struct ip_conntrack_tuple innertuple, origtuple; | |
142 | struct { | |
143 | struct icmphdr icmp; | |
144 | struct iphdr ip; | |
145 | } _in, *inside; | |
146 | struct ip_conntrack_protocol *innerproto; | |
147 | struct ip_conntrack_tuple_hash *h; | |
148 | int dataoff; | |
149 | ||
150 | IP_NF_ASSERT(skb->nfct == NULL); | |
151 | ||
152 | /* Not enough header? */ | |
153 | inside = skb_header_pointer(skb, skb->nh.iph->ihl*4, sizeof(_in), &_in); | |
154 | if (inside == NULL) | |
d63a9281 | 155 | return -NF_ACCEPT; |
1da177e4 LT |
156 | |
157 | /* Ignore ICMP's containing fragments (shouldn't happen) */ | |
158 | if (inside->ip.frag_off & htons(IP_OFFSET)) { | |
159 | DEBUGP("icmp_error_track: fragment of proto %u\n", | |
160 | inside->ip.protocol); | |
d63a9281 | 161 | return -NF_ACCEPT; |
1da177e4 LT |
162 | } |
163 | ||
080774a2 | 164 | innerproto = ip_conntrack_proto_find_get(inside->ip.protocol); |
1da177e4 LT |
165 | dataoff = skb->nh.iph->ihl*4 + sizeof(inside->icmp) + inside->ip.ihl*4; |
166 | /* Are they talking about one of our connections? */ | |
167 | if (!ip_ct_get_tuple(&inside->ip, skb, dataoff, &origtuple, innerproto)) { | |
168 | DEBUGP("icmp_error: ! get_tuple p=%u", inside->ip.protocol); | |
080774a2 | 169 | ip_conntrack_proto_put(innerproto); |
d63a9281 | 170 | return -NF_ACCEPT; |
1da177e4 LT |
171 | } |
172 | ||
173 | /* Ordinarily, we'd expect the inverted tupleproto, but it's | |
174 | been preserved inside the ICMP. */ | |
175 | if (!ip_ct_invert_tuple(&innertuple, &origtuple, innerproto)) { | |
176 | DEBUGP("icmp_error_track: Can't invert tuple\n"); | |
080774a2 | 177 | ip_conntrack_proto_put(innerproto); |
d63a9281 | 178 | return -NF_ACCEPT; |
1da177e4 | 179 | } |
080774a2 | 180 | ip_conntrack_proto_put(innerproto); |
1da177e4 LT |
181 | |
182 | *ctinfo = IP_CT_RELATED; | |
183 | ||
184 | h = ip_conntrack_find_get(&innertuple, NULL); | |
185 | if (!h) { | |
186 | /* Locally generated ICMPs will match inverted if they | |
187 | haven't been SNAT'ed yet */ | |
188 | /* FIXME: NAT code has to handle half-done double NAT --RR */ | |
189 | if (hooknum == NF_IP_LOCAL_OUT) | |
190 | h = ip_conntrack_find_get(&origtuple, NULL); | |
191 | ||
192 | if (!h) { | |
193 | DEBUGP("icmp_error_track: no match\n"); | |
d63a9281 | 194 | return -NF_ACCEPT; |
1da177e4 LT |
195 | } |
196 | /* Reverse direction from that found */ | |
197 | if (DIRECTION(h) != IP_CT_DIR_REPLY) | |
198 | *ctinfo += IP_CT_IS_REPLY; | |
199 | } else { | |
200 | if (DIRECTION(h) == IP_CT_DIR_REPLY) | |
201 | *ctinfo += IP_CT_IS_REPLY; | |
202 | } | |
203 | ||
204 | /* Update skb to refer to this connection */ | |
205 | skb->nfct = &tuplehash_to_ctrack(h)->ct_general; | |
206 | skb->nfctinfo = *ctinfo; | |
207 | return -NF_ACCEPT; | |
208 | } | |
209 | ||
210 | /* Small and modified version of icmp_rcv */ | |
211 | static int | |
212 | icmp_error(struct sk_buff *skb, enum ip_conntrack_info *ctinfo, | |
213 | unsigned int hooknum) | |
214 | { | |
215 | struct icmphdr _ih, *icmph; | |
216 | ||
217 | /* Not enough header? */ | |
218 | icmph = skb_header_pointer(skb, skb->nh.iph->ihl*4, sizeof(_ih), &_ih); | |
219 | if (icmph == NULL) { | |
220 | if (LOG_INVALID(IPPROTO_ICMP)) | |
608c8e4f | 221 | nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL, |
1da177e4 LT |
222 | "ip_ct_icmp: short packet "); |
223 | return -NF_ACCEPT; | |
224 | } | |
225 | ||
226 | /* See ip_conntrack_proto_tcp.c */ | |
39a27a35 | 227 | if (ip_conntrack_checksum && hooknum == NF_IP_PRE_ROUTING && |
96f6bf82 PM |
228 | nf_ip_checksum(skb, hooknum, skb->nh.iph->ihl * 4, 0)) { |
229 | if (LOG_INVALID(IPPROTO_ICMP)) | |
230 | nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL, | |
231 | "ip_ct_icmp: bad ICMP checksum "); | |
232 | return -NF_ACCEPT; | |
1da177e4 LT |
233 | } |
234 | ||
1da177e4 LT |
235 | /* |
236 | * 18 is the highest 'known' ICMP type. Anything else is a mystery | |
237 | * | |
238 | * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently | |
239 | * discarded. | |
240 | */ | |
241 | if (icmph->type > NR_ICMP_TYPES) { | |
242 | if (LOG_INVALID(IPPROTO_ICMP)) | |
608c8e4f | 243 | nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL, |
1da177e4 LT |
244 | "ip_ct_icmp: invalid ICMP type "); |
245 | return -NF_ACCEPT; | |
246 | } | |
247 | ||
248 | /* Need to track icmp error message? */ | |
249 | if (icmph->type != ICMP_DEST_UNREACH | |
250 | && icmph->type != ICMP_SOURCE_QUENCH | |
251 | && icmph->type != ICMP_TIME_EXCEEDED | |
252 | && icmph->type != ICMP_PARAMETERPROB | |
253 | && icmph->type != ICMP_REDIRECT) | |
254 | return NF_ACCEPT; | |
255 | ||
256 | return icmp_error_message(skb, ctinfo, hooknum); | |
257 | } | |
258 | ||
080774a2 HW |
259 | #if defined(CONFIG_IP_NF_CONNTRACK_NETLINK) || \ |
260 | defined(CONFIG_IP_NF_CONNTRACK_NETLINK_MODULE) | |
261 | static int icmp_tuple_to_nfattr(struct sk_buff *skb, | |
262 | const struct ip_conntrack_tuple *t) | |
263 | { | |
264 | NFA_PUT(skb, CTA_PROTO_ICMP_ID, sizeof(u_int16_t), | |
265 | &t->src.u.icmp.id); | |
266 | NFA_PUT(skb, CTA_PROTO_ICMP_TYPE, sizeof(u_int8_t), | |
267 | &t->dst.u.icmp.type); | |
268 | NFA_PUT(skb, CTA_PROTO_ICMP_CODE, sizeof(u_int8_t), | |
269 | &t->dst.u.icmp.code); | |
270 | ||
080774a2 HW |
271 | return 0; |
272 | ||
273 | nfattr_failure: | |
274 | return -1; | |
275 | } | |
276 | ||
277 | static int icmp_nfattr_to_tuple(struct nfattr *tb[], | |
278 | struct ip_conntrack_tuple *tuple) | |
279 | { | |
280 | if (!tb[CTA_PROTO_ICMP_TYPE-1] | |
439a9994 KPO |
281 | || !tb[CTA_PROTO_ICMP_CODE-1] |
282 | || !tb[CTA_PROTO_ICMP_ID-1]) | |
90c4656e | 283 | return -EINVAL; |
080774a2 HW |
284 | |
285 | tuple->dst.u.icmp.type = | |
286 | *(u_int8_t *)NFA_DATA(tb[CTA_PROTO_ICMP_TYPE-1]); | |
287 | tuple->dst.u.icmp.code = | |
288 | *(u_int8_t *)NFA_DATA(tb[CTA_PROTO_ICMP_CODE-1]); | |
289 | tuple->src.u.icmp.id = | |
5fd52fe0 | 290 | *(u_int16_t *)NFA_DATA(tb[CTA_PROTO_ICMP_ID-1]); |
080774a2 | 291 | |
90c4656e YK |
292 | if (tuple->dst.u.icmp.type >= sizeof(invmap) |
293 | || !invmap[tuple->dst.u.icmp.type]) | |
294 | return -EINVAL; | |
295 | ||
080774a2 HW |
296 | return 0; |
297 | } | |
298 | #endif | |
299 | ||
1da177e4 LT |
300 | struct ip_conntrack_protocol ip_conntrack_protocol_icmp = |
301 | { | |
302 | .proto = IPPROTO_ICMP, | |
303 | .name = "icmp", | |
304 | .pkt_to_tuple = icmp_pkt_to_tuple, | |
305 | .invert_tuple = icmp_invert_tuple, | |
306 | .print_tuple = icmp_print_tuple, | |
307 | .print_conntrack = icmp_print_conntrack, | |
308 | .packet = icmp_packet, | |
309 | .new = icmp_new, | |
310 | .error = icmp_error, | |
080774a2 HW |
311 | #if defined(CONFIG_IP_NF_CONNTRACK_NETLINK) || \ |
312 | defined(CONFIG_IP_NF_CONNTRACK_NETLINK_MODULE) | |
313 | .tuple_to_nfattr = icmp_tuple_to_nfattr, | |
314 | .nfattr_to_tuple = icmp_nfattr_to_tuple, | |
315 | #endif | |
1da177e4 | 316 | }; |