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9fb9cbb1 YK |
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 | * 16 Dec 2003: Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp> | |
9 | * - enable working with Layer 3 protocol independent connection tracking. | |
10 | * | |
11 | * Derived from net/ipv4/netfilter/ip_conntrack_proto_icmp.c | |
12 | */ | |
13 | ||
14 | #include <linux/types.h> | |
15 | #include <linux/sched.h> | |
16 | #include <linux/timer.h> | |
17 | #include <linux/netfilter.h> | |
18 | #include <linux/in.h> | |
19 | #include <linux/icmp.h> | |
20 | #include <linux/seq_file.h> | |
21 | #include <net/ip.h> | |
22 | #include <net/checksum.h> | |
23 | #include <linux/netfilter_ipv4.h> | |
24 | #include <net/netfilter/nf_conntrack_tuple.h> | |
605dcad6 | 25 | #include <net/netfilter/nf_conntrack_l4proto.h> |
9fb9cbb1 YK |
26 | #include <net/netfilter/nf_conntrack_core.h> |
27 | ||
933a41e7 | 28 | static unsigned long nf_ct_icmp_timeout __read_mostly = 30*HZ; |
9fb9cbb1 YK |
29 | |
30 | #if 0 | |
31 | #define DEBUGP printk | |
32 | #else | |
33 | #define DEBUGP(format, args...) | |
34 | #endif | |
35 | ||
36 | static int icmp_pkt_to_tuple(const struct sk_buff *skb, | |
37 | unsigned int dataoff, | |
38 | struct nf_conntrack_tuple *tuple) | |
39 | { | |
40 | struct icmphdr _hdr, *hp; | |
41 | ||
42 | hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr); | |
43 | if (hp == NULL) | |
44 | return 0; | |
45 | ||
46 | tuple->dst.u.icmp.type = hp->type; | |
47 | tuple->src.u.icmp.id = hp->un.echo.id; | |
48 | tuple->dst.u.icmp.code = hp->code; | |
49 | ||
50 | return 1; | |
51 | } | |
52 | ||
c1d10adb PNA |
53 | /* Add 1; spaces filled with 0. */ |
54 | static const u_int8_t invmap[] = { | |
55 | [ICMP_ECHO] = ICMP_ECHOREPLY + 1, | |
56 | [ICMP_ECHOREPLY] = ICMP_ECHO + 1, | |
57 | [ICMP_TIMESTAMP] = ICMP_TIMESTAMPREPLY + 1, | |
58 | [ICMP_TIMESTAMPREPLY] = ICMP_TIMESTAMP + 1, | |
59 | [ICMP_INFO_REQUEST] = ICMP_INFO_REPLY + 1, | |
60 | [ICMP_INFO_REPLY] = ICMP_INFO_REQUEST + 1, | |
61 | [ICMP_ADDRESS] = ICMP_ADDRESSREPLY + 1, | |
62 | [ICMP_ADDRESSREPLY] = ICMP_ADDRESS + 1 | |
63 | }; | |
64 | ||
9fb9cbb1 YK |
65 | static int icmp_invert_tuple(struct nf_conntrack_tuple *tuple, |
66 | const struct nf_conntrack_tuple *orig) | |
67 | { | |
9fb9cbb1 YK |
68 | if (orig->dst.u.icmp.type >= sizeof(invmap) |
69 | || !invmap[orig->dst.u.icmp.type]) | |
70 | return 0; | |
71 | ||
72 | tuple->src.u.icmp.id = orig->src.u.icmp.id; | |
73 | tuple->dst.u.icmp.type = invmap[orig->dst.u.icmp.type] - 1; | |
74 | tuple->dst.u.icmp.code = orig->dst.u.icmp.code; | |
75 | return 1; | |
76 | } | |
77 | ||
78 | /* Print out the per-protocol part of the tuple. */ | |
79 | static int icmp_print_tuple(struct seq_file *s, | |
80 | const struct nf_conntrack_tuple *tuple) | |
81 | { | |
82 | return seq_printf(s, "type=%u code=%u id=%u ", | |
83 | tuple->dst.u.icmp.type, | |
84 | tuple->dst.u.icmp.code, | |
85 | ntohs(tuple->src.u.icmp.id)); | |
86 | } | |
87 | ||
88 | /* Print out the private part of the conntrack. */ | |
89 | static int icmp_print_conntrack(struct seq_file *s, | |
90 | const struct nf_conn *conntrack) | |
91 | { | |
92 | return 0; | |
93 | } | |
94 | ||
95 | /* Returns verdict for packet, or -1 for invalid. */ | |
96 | static int icmp_packet(struct nf_conn *ct, | |
97 | const struct sk_buff *skb, | |
98 | unsigned int dataoff, | |
99 | enum ip_conntrack_info ctinfo, | |
100 | int pf, | |
101 | unsigned int hooknum) | |
102 | { | |
103 | /* Try to delete connection immediately after all replies: | |
e905a9ed YH |
104 | won't actually vanish as we still have skb, and del_timer |
105 | means this will only run once even if count hits zero twice | |
106 | (theoretically possible with SMP) */ | |
9fb9cbb1 YK |
107 | if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) { |
108 | if (atomic_dec_and_test(&ct->proto.icmp.count) | |
109 | && del_timer(&ct->timeout)) | |
110 | ct->timeout.function((unsigned long)ct); | |
111 | } else { | |
112 | atomic_inc(&ct->proto.icmp.count); | |
113 | nf_conntrack_event_cache(IPCT_PROTOINFO_VOLATILE, skb); | |
114 | nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_icmp_timeout); | |
115 | } | |
116 | ||
117 | return NF_ACCEPT; | |
118 | } | |
119 | ||
120 | /* Called when a new connection for this protocol found. */ | |
121 | static int icmp_new(struct nf_conn *conntrack, | |
122 | const struct sk_buff *skb, unsigned int dataoff) | |
123 | { | |
c1d10adb PNA |
124 | static const u_int8_t valid_new[] = { |
125 | [ICMP_ECHO] = 1, | |
126 | [ICMP_TIMESTAMP] = 1, | |
127 | [ICMP_INFO_REQUEST] = 1, | |
128 | [ICMP_ADDRESS] = 1 | |
129 | }; | |
9fb9cbb1 YK |
130 | |
131 | if (conntrack->tuplehash[0].tuple.dst.u.icmp.type >= sizeof(valid_new) | |
132 | || !valid_new[conntrack->tuplehash[0].tuple.dst.u.icmp.type]) { | |
133 | /* Can't create a new ICMP `conn' with this. */ | |
134 | DEBUGP("icmp: can't create new conn with type %u\n", | |
135 | conntrack->tuplehash[0].tuple.dst.u.icmp.type); | |
136 | NF_CT_DUMP_TUPLE(&conntrack->tuplehash[0].tuple); | |
137 | return 0; | |
138 | } | |
139 | atomic_set(&conntrack->proto.icmp.count, 0); | |
140 | return 1; | |
141 | } | |
142 | ||
143 | extern struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv4; | |
144 | /* Returns conntrack if it dealt with ICMP, and filled in skb fields */ | |
145 | static int | |
146 | icmp_error_message(struct sk_buff *skb, | |
e905a9ed YH |
147 | enum ip_conntrack_info *ctinfo, |
148 | unsigned int hooknum) | |
9fb9cbb1 YK |
149 | { |
150 | struct nf_conntrack_tuple innertuple, origtuple; | |
151 | struct { | |
152 | struct icmphdr icmp; | |
153 | struct iphdr ip; | |
154 | } _in, *inside; | |
605dcad6 | 155 | struct nf_conntrack_l4proto *innerproto; |
9fb9cbb1 YK |
156 | struct nf_conntrack_tuple_hash *h; |
157 | int dataoff; | |
158 | ||
159 | NF_CT_ASSERT(skb->nfct == NULL); | |
160 | ||
161 | /* Not enough header? */ | |
162 | inside = skb_header_pointer(skb, skb->nh.iph->ihl*4, sizeof(_in), &_in); | |
163 | if (inside == NULL) | |
164 | return -NF_ACCEPT; | |
165 | ||
166 | /* Ignore ICMP's containing fragments (shouldn't happen) */ | |
167 | if (inside->ip.frag_off & htons(IP_OFFSET)) { | |
168 | DEBUGP("icmp_error_message: fragment of proto %u\n", | |
169 | inside->ip.protocol); | |
170 | return -NF_ACCEPT; | |
171 | } | |
172 | ||
923f4902 | 173 | /* rcu_read_lock()ed by nf_hook_slow */ |
605dcad6 | 174 | innerproto = __nf_ct_l4proto_find(PF_INET, inside->ip.protocol); |
923f4902 | 175 | |
9fb9cbb1 YK |
176 | dataoff = skb->nh.iph->ihl*4 + sizeof(inside->icmp); |
177 | /* Are they talking about one of our connections? */ | |
178 | if (!nf_ct_get_tuple(skb, dataoff, dataoff + inside->ip.ihl*4, PF_INET, | |
179 | inside->ip.protocol, &origtuple, | |
180 | &nf_conntrack_l3proto_ipv4, innerproto)) { | |
181 | DEBUGP("icmp_error_message: ! get_tuple p=%u", | |
182 | inside->ip.protocol); | |
183 | return -NF_ACCEPT; | |
184 | } | |
185 | ||
e905a9ed YH |
186 | /* Ordinarily, we'd expect the inverted tupleproto, but it's |
187 | been preserved inside the ICMP. */ | |
188 | if (!nf_ct_invert_tuple(&innertuple, &origtuple, | |
9fb9cbb1 YK |
189 | &nf_conntrack_l3proto_ipv4, innerproto)) { |
190 | DEBUGP("icmp_error_message: no match\n"); | |
191 | return -NF_ACCEPT; | |
192 | } | |
193 | ||
194 | *ctinfo = IP_CT_RELATED; | |
195 | ||
196 | h = nf_conntrack_find_get(&innertuple, NULL); | |
197 | if (!h) { | |
198 | /* Locally generated ICMPs will match inverted if they | |
199 | haven't been SNAT'ed yet */ | |
200 | /* FIXME: NAT code has to handle half-done double NAT --RR */ | |
201 | if (hooknum == NF_IP_LOCAL_OUT) | |
202 | h = nf_conntrack_find_get(&origtuple, NULL); | |
203 | ||
204 | if (!h) { | |
205 | DEBUGP("icmp_error_message: no match\n"); | |
206 | return -NF_ACCEPT; | |
207 | } | |
208 | ||
209 | /* Reverse direction from that found */ | |
210 | if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY) | |
211 | *ctinfo += IP_CT_IS_REPLY; | |
212 | } else { | |
213 | if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY) | |
214 | *ctinfo += IP_CT_IS_REPLY; | |
215 | } | |
216 | ||
e905a9ed YH |
217 | /* Update skb to refer to this connection */ |
218 | skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general; | |
219 | skb->nfctinfo = *ctinfo; | |
220 | return -NF_ACCEPT; | |
9fb9cbb1 YK |
221 | } |
222 | ||
223 | /* Small and modified version of icmp_rcv */ | |
224 | static int | |
225 | icmp_error(struct sk_buff *skb, unsigned int dataoff, | |
226 | enum ip_conntrack_info *ctinfo, int pf, unsigned int hooknum) | |
227 | { | |
228 | struct icmphdr _ih, *icmph; | |
229 | ||
230 | /* Not enough header? */ | |
231 | icmph = skb_header_pointer(skb, skb->nh.iph->ihl*4, sizeof(_ih), &_ih); | |
232 | if (icmph == NULL) { | |
233 | if (LOG_INVALID(IPPROTO_ICMP)) | |
234 | nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL, | |
235 | "nf_ct_icmp: short packet "); | |
236 | return -NF_ACCEPT; | |
237 | } | |
238 | ||
239 | /* See ip_conntrack_proto_tcp.c */ | |
39a27a35 | 240 | if (nf_conntrack_checksum && hooknum == NF_IP_PRE_ROUTING && |
96f6bf82 | 241 | nf_ip_checksum(skb, hooknum, dataoff, 0)) { |
9fb9cbb1 YK |
242 | if (LOG_INVALID(IPPROTO_ICMP)) |
243 | nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL, | |
244 | "nf_ct_icmp: bad HW ICMP checksum "); | |
245 | return -NF_ACCEPT; | |
9fb9cbb1 YK |
246 | } |
247 | ||
9fb9cbb1 YK |
248 | /* |
249 | * 18 is the highest 'known' ICMP type. Anything else is a mystery | |
250 | * | |
251 | * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently | |
252 | * discarded. | |
253 | */ | |
254 | if (icmph->type > NR_ICMP_TYPES) { | |
255 | if (LOG_INVALID(IPPROTO_ICMP)) | |
256 | nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL, | |
257 | "nf_ct_icmp: invalid ICMP type "); | |
258 | return -NF_ACCEPT; | |
259 | } | |
260 | ||
261 | /* Need to track icmp error message? */ | |
262 | if (icmph->type != ICMP_DEST_UNREACH | |
263 | && icmph->type != ICMP_SOURCE_QUENCH | |
264 | && icmph->type != ICMP_TIME_EXCEEDED | |
265 | && icmph->type != ICMP_PARAMETERPROB | |
266 | && icmph->type != ICMP_REDIRECT) | |
267 | return NF_ACCEPT; | |
268 | ||
269 | return icmp_error_message(skb, ctinfo, hooknum); | |
270 | } | |
271 | ||
c1d10adb PNA |
272 | #if defined(CONFIG_NF_CT_NETLINK) || \ |
273 | defined(CONFIG_NF_CT_NETLINK_MODULE) | |
274 | ||
275 | #include <linux/netfilter/nfnetlink.h> | |
276 | #include <linux/netfilter/nfnetlink_conntrack.h> | |
277 | ||
278 | static int icmp_tuple_to_nfattr(struct sk_buff *skb, | |
279 | const struct nf_conntrack_tuple *t) | |
280 | { | |
281 | NFA_PUT(skb, CTA_PROTO_ICMP_ID, sizeof(u_int16_t), | |
282 | &t->src.u.icmp.id); | |
283 | NFA_PUT(skb, CTA_PROTO_ICMP_TYPE, sizeof(u_int8_t), | |
284 | &t->dst.u.icmp.type); | |
285 | NFA_PUT(skb, CTA_PROTO_ICMP_CODE, sizeof(u_int8_t), | |
286 | &t->dst.u.icmp.code); | |
287 | ||
288 | return 0; | |
289 | ||
290 | nfattr_failure: | |
291 | return -1; | |
292 | } | |
293 | ||
294 | static const size_t cta_min_proto[CTA_PROTO_MAX] = { | |
295 | [CTA_PROTO_ICMP_TYPE-1] = sizeof(u_int8_t), | |
296 | [CTA_PROTO_ICMP_CODE-1] = sizeof(u_int8_t), | |
297 | [CTA_PROTO_ICMP_ID-1] = sizeof(u_int16_t) | |
298 | }; | |
299 | ||
300 | static int icmp_nfattr_to_tuple(struct nfattr *tb[], | |
301 | struct nf_conntrack_tuple *tuple) | |
302 | { | |
303 | if (!tb[CTA_PROTO_ICMP_TYPE-1] | |
304 | || !tb[CTA_PROTO_ICMP_CODE-1] | |
305 | || !tb[CTA_PROTO_ICMP_ID-1]) | |
306 | return -EINVAL; | |
307 | ||
308 | if (nfattr_bad_size(tb, CTA_PROTO_MAX, cta_min_proto)) | |
309 | return -EINVAL; | |
310 | ||
e905a9ed | 311 | tuple->dst.u.icmp.type = |
c1d10adb PNA |
312 | *(u_int8_t *)NFA_DATA(tb[CTA_PROTO_ICMP_TYPE-1]); |
313 | tuple->dst.u.icmp.code = | |
314 | *(u_int8_t *)NFA_DATA(tb[CTA_PROTO_ICMP_CODE-1]); | |
315 | tuple->src.u.icmp.id = | |
bff9a89b | 316 | *(__be16 *)NFA_DATA(tb[CTA_PROTO_ICMP_ID-1]); |
c1d10adb PNA |
317 | |
318 | if (tuple->dst.u.icmp.type >= sizeof(invmap) | |
319 | || !invmap[tuple->dst.u.icmp.type]) | |
320 | return -EINVAL; | |
321 | ||
322 | return 0; | |
323 | } | |
324 | #endif | |
325 | ||
933a41e7 PM |
326 | #ifdef CONFIG_SYSCTL |
327 | static struct ctl_table_header *icmp_sysctl_header; | |
328 | static struct ctl_table icmp_sysctl_table[] = { | |
329 | { | |
330 | .ctl_name = NET_NF_CONNTRACK_ICMP_TIMEOUT, | |
331 | .procname = "nf_conntrack_icmp_timeout", | |
332 | .data = &nf_ct_icmp_timeout, | |
333 | .maxlen = sizeof(unsigned int), | |
334 | .mode = 0644, | |
335 | .proc_handler = &proc_dointvec_jiffies, | |
336 | }, | |
e905a9ed | 337 | { |
933a41e7 PM |
338 | .ctl_name = 0 |
339 | } | |
340 | }; | |
a999e683 PM |
341 | #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT |
342 | static struct ctl_table icmp_compat_sysctl_table[] = { | |
343 | { | |
344 | .ctl_name = NET_IPV4_NF_CONNTRACK_ICMP_TIMEOUT, | |
345 | .procname = "ip_conntrack_icmp_timeout", | |
346 | .data = &nf_ct_icmp_timeout, | |
347 | .maxlen = sizeof(unsigned int), | |
348 | .mode = 0644, | |
349 | .proc_handler = &proc_dointvec_jiffies, | |
350 | }, | |
e905a9ed | 351 | { |
a999e683 PM |
352 | .ctl_name = 0 |
353 | } | |
354 | }; | |
355 | #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */ | |
933a41e7 PM |
356 | #endif /* CONFIG_SYSCTL */ |
357 | ||
605dcad6 | 358 | struct nf_conntrack_l4proto nf_conntrack_l4proto_icmp = |
9fb9cbb1 | 359 | { |
9fb9cbb1 | 360 | .l3proto = PF_INET, |
605dcad6 | 361 | .l4proto = IPPROTO_ICMP, |
9fb9cbb1 YK |
362 | .name = "icmp", |
363 | .pkt_to_tuple = icmp_pkt_to_tuple, | |
364 | .invert_tuple = icmp_invert_tuple, | |
365 | .print_tuple = icmp_print_tuple, | |
366 | .print_conntrack = icmp_print_conntrack, | |
367 | .packet = icmp_packet, | |
368 | .new = icmp_new, | |
369 | .error = icmp_error, | |
370 | .destroy = NULL, | |
c1d10adb PNA |
371 | .me = NULL, |
372 | #if defined(CONFIG_NF_CT_NETLINK) || \ | |
373 | defined(CONFIG_NF_CT_NETLINK_MODULE) | |
374 | .tuple_to_nfattr = icmp_tuple_to_nfattr, | |
375 | .nfattr_to_tuple = icmp_nfattr_to_tuple, | |
376 | #endif | |
933a41e7 PM |
377 | #ifdef CONFIG_SYSCTL |
378 | .ctl_table_header = &icmp_sysctl_header, | |
379 | .ctl_table = icmp_sysctl_table, | |
a999e683 PM |
380 | #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT |
381 | .ctl_compat_table = icmp_compat_sysctl_table, | |
382 | #endif | |
933a41e7 | 383 | #endif |
9fb9cbb1 | 384 | }; |
13b18339 | 385 | EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_icmp); |