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Yasuyuki Kozakai9fb9cbb2005-11-09 16:38:16 -08001/* (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>
Yasuyuki Kozakai9fb9cbb2005-11-09 16:38:16 -080015#include <linux/timer.h>
16#include <linux/netfilter.h>
17#include <linux/in.h>
18#include <linux/icmp.h>
19#include <linux/seq_file.h>
20#include <net/ip.h>
21#include <net/checksum.h>
22#include <linux/netfilter_ipv4.h>
23#include <net/netfilter/nf_conntrack_tuple.h>
Martin Josefsson605dcad2006-11-29 02:35:06 +010024#include <net/netfilter/nf_conntrack_l4proto.h>
Yasuyuki Kozakai9fb9cbb2005-11-09 16:38:16 -080025#include <net/netfilter/nf_conntrack_core.h>
26
Patrick McHardy933a41e2006-11-29 02:35:18 +010027static unsigned long nf_ct_icmp_timeout __read_mostly = 30*HZ;
Yasuyuki Kozakai9fb9cbb2005-11-09 16:38:16 -080028
29#if 0
30#define DEBUGP printk
31#else
32#define DEBUGP(format, args...)
33#endif
34
35static int icmp_pkt_to_tuple(const struct sk_buff *skb,
36 unsigned int dataoff,
37 struct nf_conntrack_tuple *tuple)
38{
39 struct icmphdr _hdr, *hp;
40
41 hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
42 if (hp == NULL)
43 return 0;
44
45 tuple->dst.u.icmp.type = hp->type;
46 tuple->src.u.icmp.id = hp->un.echo.id;
47 tuple->dst.u.icmp.code = hp->code;
48
49 return 1;
50}
51
Pablo Neira Ayusoc1d10ad2006-01-05 12:19:05 -080052/* Add 1; spaces filled with 0. */
53static const u_int8_t invmap[] = {
54 [ICMP_ECHO] = ICMP_ECHOREPLY + 1,
55 [ICMP_ECHOREPLY] = ICMP_ECHO + 1,
56 [ICMP_TIMESTAMP] = ICMP_TIMESTAMPREPLY + 1,
57 [ICMP_TIMESTAMPREPLY] = ICMP_TIMESTAMP + 1,
58 [ICMP_INFO_REQUEST] = ICMP_INFO_REPLY + 1,
59 [ICMP_INFO_REPLY] = ICMP_INFO_REQUEST + 1,
60 [ICMP_ADDRESS] = ICMP_ADDRESSREPLY + 1,
61 [ICMP_ADDRESSREPLY] = ICMP_ADDRESS + 1
62};
63
Yasuyuki Kozakai9fb9cbb2005-11-09 16:38:16 -080064static int icmp_invert_tuple(struct nf_conntrack_tuple *tuple,
65 const struct nf_conntrack_tuple *orig)
66{
Yasuyuki Kozakai9fb9cbb2005-11-09 16:38:16 -080067 if (orig->dst.u.icmp.type >= sizeof(invmap)
68 || !invmap[orig->dst.u.icmp.type])
69 return 0;
70
71 tuple->src.u.icmp.id = orig->src.u.icmp.id;
72 tuple->dst.u.icmp.type = invmap[orig->dst.u.icmp.type] - 1;
73 tuple->dst.u.icmp.code = orig->dst.u.icmp.code;
74 return 1;
75}
76
77/* Print out the per-protocol part of the tuple. */
78static int icmp_print_tuple(struct seq_file *s,
79 const struct nf_conntrack_tuple *tuple)
80{
81 return seq_printf(s, "type=%u code=%u id=%u ",
82 tuple->dst.u.icmp.type,
83 tuple->dst.u.icmp.code,
84 ntohs(tuple->src.u.icmp.id));
85}
86
87/* Print out the private part of the conntrack. */
88static int icmp_print_conntrack(struct seq_file *s,
89 const struct nf_conn *conntrack)
90{
91 return 0;
92}
93
94/* Returns verdict for packet, or -1 for invalid. */
95static int icmp_packet(struct nf_conn *ct,
96 const struct sk_buff *skb,
97 unsigned int dataoff,
98 enum ip_conntrack_info ctinfo,
99 int pf,
100 unsigned int hooknum)
101{
102 /* Try to delete connection immediately after all replies:
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900103 won't actually vanish as we still have skb, and del_timer
104 means this will only run once even if count hits zero twice
105 (theoretically possible with SMP) */
Yasuyuki Kozakai9fb9cbb2005-11-09 16:38:16 -0800106 if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
107 if (atomic_dec_and_test(&ct->proto.icmp.count)
108 && del_timer(&ct->timeout))
109 ct->timeout.function((unsigned long)ct);
110 } else {
111 atomic_inc(&ct->proto.icmp.count);
112 nf_conntrack_event_cache(IPCT_PROTOINFO_VOLATILE, skb);
113 nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_icmp_timeout);
114 }
115
116 return NF_ACCEPT;
117}
118
119/* Called when a new connection for this protocol found. */
120static int icmp_new(struct nf_conn *conntrack,
121 const struct sk_buff *skb, unsigned int dataoff)
122{
Pablo Neira Ayusoc1d10ad2006-01-05 12:19:05 -0800123 static const u_int8_t valid_new[] = {
124 [ICMP_ECHO] = 1,
125 [ICMP_TIMESTAMP] = 1,
126 [ICMP_INFO_REQUEST] = 1,
127 [ICMP_ADDRESS] = 1
128 };
Yasuyuki Kozakai9fb9cbb2005-11-09 16:38:16 -0800129
130 if (conntrack->tuplehash[0].tuple.dst.u.icmp.type >= sizeof(valid_new)
131 || !valid_new[conntrack->tuplehash[0].tuple.dst.u.icmp.type]) {
132 /* Can't create a new ICMP `conn' with this. */
133 DEBUGP("icmp: can't create new conn with type %u\n",
134 conntrack->tuplehash[0].tuple.dst.u.icmp.type);
135 NF_CT_DUMP_TUPLE(&conntrack->tuplehash[0].tuple);
136 return 0;
137 }
138 atomic_set(&conntrack->proto.icmp.count, 0);
139 return 1;
140}
141
142extern struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv4;
143/* Returns conntrack if it dealt with ICMP, and filled in skb fields */
144static int
145icmp_error_message(struct sk_buff *skb,
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900146 enum ip_conntrack_info *ctinfo,
147 unsigned int hooknum)
Yasuyuki Kozakai9fb9cbb2005-11-09 16:38:16 -0800148{
149 struct nf_conntrack_tuple innertuple, origtuple;
150 struct {
151 struct icmphdr icmp;
152 struct iphdr ip;
153 } _in, *inside;
Martin Josefsson605dcad2006-11-29 02:35:06 +0100154 struct nf_conntrack_l4proto *innerproto;
Yasuyuki Kozakai9fb9cbb2005-11-09 16:38:16 -0800155 struct nf_conntrack_tuple_hash *h;
156 int dataoff;
157
158 NF_CT_ASSERT(skb->nfct == NULL);
159
160 /* Not enough header? */
161 inside = skb_header_pointer(skb, skb->nh.iph->ihl*4, sizeof(_in), &_in);
162 if (inside == NULL)
163 return -NF_ACCEPT;
164
165 /* Ignore ICMP's containing fragments (shouldn't happen) */
166 if (inside->ip.frag_off & htons(IP_OFFSET)) {
167 DEBUGP("icmp_error_message: fragment of proto %u\n",
168 inside->ip.protocol);
169 return -NF_ACCEPT;
170 }
171
Patrick McHardy923f4902007-02-12 11:12:57 -0800172 /* rcu_read_lock()ed by nf_hook_slow */
Martin Josefsson605dcad2006-11-29 02:35:06 +0100173 innerproto = __nf_ct_l4proto_find(PF_INET, inside->ip.protocol);
Patrick McHardy923f4902007-02-12 11:12:57 -0800174
Yasuyuki Kozakai9fb9cbb2005-11-09 16:38:16 -0800175 dataoff = skb->nh.iph->ihl*4 + sizeof(inside->icmp);
176 /* Are they talking about one of our connections? */
177 if (!nf_ct_get_tuple(skb, dataoff, dataoff + inside->ip.ihl*4, PF_INET,
178 inside->ip.protocol, &origtuple,
179 &nf_conntrack_l3proto_ipv4, innerproto)) {
180 DEBUGP("icmp_error_message: ! get_tuple p=%u",
181 inside->ip.protocol);
182 return -NF_ACCEPT;
183 }
184
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900185 /* Ordinarily, we'd expect the inverted tupleproto, but it's
186 been preserved inside the ICMP. */
187 if (!nf_ct_invert_tuple(&innertuple, &origtuple,
Yasuyuki Kozakai9fb9cbb2005-11-09 16:38:16 -0800188 &nf_conntrack_l3proto_ipv4, innerproto)) {
189 DEBUGP("icmp_error_message: no match\n");
190 return -NF_ACCEPT;
191 }
192
193 *ctinfo = IP_CT_RELATED;
194
195 h = nf_conntrack_find_get(&innertuple, NULL);
196 if (!h) {
197 /* Locally generated ICMPs will match inverted if they
198 haven't been SNAT'ed yet */
199 /* FIXME: NAT code has to handle half-done double NAT --RR */
200 if (hooknum == NF_IP_LOCAL_OUT)
201 h = nf_conntrack_find_get(&origtuple, NULL);
202
203 if (!h) {
204 DEBUGP("icmp_error_message: no match\n");
205 return -NF_ACCEPT;
206 }
207
208 /* Reverse direction from that found */
209 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
210 *ctinfo += IP_CT_IS_REPLY;
211 } else {
212 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
213 *ctinfo += IP_CT_IS_REPLY;
214 }
215
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900216 /* Update skb to refer to this connection */
217 skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general;
218 skb->nfctinfo = *ctinfo;
219 return -NF_ACCEPT;
Yasuyuki Kozakai9fb9cbb2005-11-09 16:38:16 -0800220}
221
222/* Small and modified version of icmp_rcv */
223static int
224icmp_error(struct sk_buff *skb, unsigned int dataoff,
225 enum ip_conntrack_info *ctinfo, int pf, unsigned int hooknum)
226{
227 struct icmphdr _ih, *icmph;
228
229 /* Not enough header? */
230 icmph = skb_header_pointer(skb, skb->nh.iph->ihl*4, sizeof(_ih), &_ih);
231 if (icmph == NULL) {
232 if (LOG_INVALID(IPPROTO_ICMP))
233 nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
234 "nf_ct_icmp: short packet ");
235 return -NF_ACCEPT;
236 }
237
238 /* See ip_conntrack_proto_tcp.c */
Patrick McHardy39a27a32006-05-29 18:23:54 -0700239 if (nf_conntrack_checksum && hooknum == NF_IP_PRE_ROUTING &&
Patrick McHardy96f6bf82006-04-06 14:19:24 -0700240 nf_ip_checksum(skb, hooknum, dataoff, 0)) {
Yasuyuki Kozakai9fb9cbb2005-11-09 16:38:16 -0800241 if (LOG_INVALID(IPPROTO_ICMP))
242 nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
243 "nf_ct_icmp: bad HW ICMP checksum ");
244 return -NF_ACCEPT;
Yasuyuki Kozakai9fb9cbb2005-11-09 16:38:16 -0800245 }
246
Yasuyuki Kozakai9fb9cbb2005-11-09 16:38:16 -0800247 /*
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 "nf_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
Pablo Neira Ayusoc1d10ad2006-01-05 12:19:05 -0800271#if defined(CONFIG_NF_CT_NETLINK) || \
272 defined(CONFIG_NF_CT_NETLINK_MODULE)
273
274#include <linux/netfilter/nfnetlink.h>
275#include <linux/netfilter/nfnetlink_conntrack.h>
276
277static int icmp_tuple_to_nfattr(struct sk_buff *skb,
278 const struct nf_conntrack_tuple *t)
279{
280 NFA_PUT(skb, CTA_PROTO_ICMP_ID, sizeof(u_int16_t),
281 &t->src.u.icmp.id);
282 NFA_PUT(skb, CTA_PROTO_ICMP_TYPE, sizeof(u_int8_t),
283 &t->dst.u.icmp.type);
284 NFA_PUT(skb, CTA_PROTO_ICMP_CODE, sizeof(u_int8_t),
285 &t->dst.u.icmp.code);
286
287 return 0;
288
289nfattr_failure:
290 return -1;
291}
292
293static const size_t cta_min_proto[CTA_PROTO_MAX] = {
294 [CTA_PROTO_ICMP_TYPE-1] = sizeof(u_int8_t),
295 [CTA_PROTO_ICMP_CODE-1] = sizeof(u_int8_t),
296 [CTA_PROTO_ICMP_ID-1] = sizeof(u_int16_t)
297};
298
299static int icmp_nfattr_to_tuple(struct nfattr *tb[],
300 struct nf_conntrack_tuple *tuple)
301{
302 if (!tb[CTA_PROTO_ICMP_TYPE-1]
303 || !tb[CTA_PROTO_ICMP_CODE-1]
304 || !tb[CTA_PROTO_ICMP_ID-1])
305 return -EINVAL;
306
307 if (nfattr_bad_size(tb, CTA_PROTO_MAX, cta_min_proto))
308 return -EINVAL;
309
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900310 tuple->dst.u.icmp.type =
Pablo Neira Ayusoc1d10ad2006-01-05 12:19:05 -0800311 *(u_int8_t *)NFA_DATA(tb[CTA_PROTO_ICMP_TYPE-1]);
312 tuple->dst.u.icmp.code =
313 *(u_int8_t *)NFA_DATA(tb[CTA_PROTO_ICMP_CODE-1]);
314 tuple->src.u.icmp.id =
Patrick McHardybff9a892006-12-02 22:05:08 -0800315 *(__be16 *)NFA_DATA(tb[CTA_PROTO_ICMP_ID-1]);
Pablo Neira Ayusoc1d10ad2006-01-05 12:19:05 -0800316
317 if (tuple->dst.u.icmp.type >= sizeof(invmap)
318 || !invmap[tuple->dst.u.icmp.type])
319 return -EINVAL;
320
321 return 0;
322}
323#endif
324
Patrick McHardy933a41e2006-11-29 02:35:18 +0100325#ifdef CONFIG_SYSCTL
326static struct ctl_table_header *icmp_sysctl_header;
327static struct ctl_table icmp_sysctl_table[] = {
328 {
329 .ctl_name = NET_NF_CONNTRACK_ICMP_TIMEOUT,
330 .procname = "nf_conntrack_icmp_timeout",
331 .data = &nf_ct_icmp_timeout,
332 .maxlen = sizeof(unsigned int),
333 .mode = 0644,
334 .proc_handler = &proc_dointvec_jiffies,
335 },
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900336 {
Patrick McHardy933a41e2006-11-29 02:35:18 +0100337 .ctl_name = 0
338 }
339};
Patrick McHardya999e682006-11-29 02:35:20 +0100340#ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
341static struct ctl_table icmp_compat_sysctl_table[] = {
342 {
343 .ctl_name = NET_IPV4_NF_CONNTRACK_ICMP_TIMEOUT,
344 .procname = "ip_conntrack_icmp_timeout",
345 .data = &nf_ct_icmp_timeout,
346 .maxlen = sizeof(unsigned int),
347 .mode = 0644,
348 .proc_handler = &proc_dointvec_jiffies,
349 },
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900350 {
Patrick McHardya999e682006-11-29 02:35:20 +0100351 .ctl_name = 0
352 }
353};
354#endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
Patrick McHardy933a41e2006-11-29 02:35:18 +0100355#endif /* CONFIG_SYSCTL */
356
Martin Josefsson605dcad2006-11-29 02:35:06 +0100357struct nf_conntrack_l4proto nf_conntrack_l4proto_icmp =
Yasuyuki Kozakai9fb9cbb2005-11-09 16:38:16 -0800358{
Yasuyuki Kozakai9fb9cbb2005-11-09 16:38:16 -0800359 .l3proto = PF_INET,
Martin Josefsson605dcad2006-11-29 02:35:06 +0100360 .l4proto = IPPROTO_ICMP,
Yasuyuki Kozakai9fb9cbb2005-11-09 16:38:16 -0800361 .name = "icmp",
362 .pkt_to_tuple = icmp_pkt_to_tuple,
363 .invert_tuple = icmp_invert_tuple,
364 .print_tuple = icmp_print_tuple,
365 .print_conntrack = icmp_print_conntrack,
366 .packet = icmp_packet,
367 .new = icmp_new,
368 .error = icmp_error,
369 .destroy = NULL,
Pablo Neira Ayusoc1d10ad2006-01-05 12:19:05 -0800370 .me = NULL,
371#if defined(CONFIG_NF_CT_NETLINK) || \
372 defined(CONFIG_NF_CT_NETLINK_MODULE)
373 .tuple_to_nfattr = icmp_tuple_to_nfattr,
374 .nfattr_to_tuple = icmp_nfattr_to_tuple,
375#endif
Patrick McHardy933a41e2006-11-29 02:35:18 +0100376#ifdef CONFIG_SYSCTL
377 .ctl_table_header = &icmp_sysctl_header,
378 .ctl_table = icmp_sysctl_table,
Patrick McHardya999e682006-11-29 02:35:20 +0100379#ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
380 .ctl_compat_table = icmp_compat_sysctl_table,
381#endif
Patrick McHardy933a41e2006-11-29 02:35:18 +0100382#endif
Yasuyuki Kozakai9fb9cbb2005-11-09 16:38:16 -0800383};
Patrick McHardy13b18332006-12-02 22:11:25 -0800384EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_icmp);