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/timer.h>
11 #include <linux/netfilter.h>
12 #include <linux/in.h>
13 #include <linux/icmp.h>
14 #include <linux/seq_file.h>
15 #include <net/ip.h>
16 #include <net/checksum.h>
17 #include <linux/netfilter_ipv4.h>
18 #include <net/netfilter/nf_conntrack_tuple.h>
19 #include <net/netfilter/nf_conntrack_l4proto.h>
20 #include <net/netfilter/nf_conntrack_core.h>
21 #include <net/netfilter/nf_log.h>
22
23 static unsigned long nf_ct_icmp_timeout __read_mostly = 30*HZ;
24
25 static int icmp_pkt_to_tuple(const struct sk_buff *skb,
26 unsigned int dataoff,
27 struct nf_conntrack_tuple *tuple)
28 {
29 const struct icmphdr *hp;
30 struct icmphdr _hdr;
31
32 hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
33 if (hp == NULL)
34 return 0;
35
36 tuple->dst.u.icmp.type = hp->type;
37 tuple->src.u.icmp.id = hp->un.echo.id;
38 tuple->dst.u.icmp.code = hp->code;
39
40 return 1;
41 }
42
43 /* Add 1; spaces filled with 0. */
44 static const u_int8_t invmap[] = {
45 [ICMP_ECHO] = ICMP_ECHOREPLY + 1,
46 [ICMP_ECHOREPLY] = ICMP_ECHO + 1,
47 [ICMP_TIMESTAMP] = ICMP_TIMESTAMPREPLY + 1,
48 [ICMP_TIMESTAMPREPLY] = ICMP_TIMESTAMP + 1,
49 [ICMP_INFO_REQUEST] = ICMP_INFO_REPLY + 1,
50 [ICMP_INFO_REPLY] = ICMP_INFO_REQUEST + 1,
51 [ICMP_ADDRESS] = ICMP_ADDRESSREPLY + 1,
52 [ICMP_ADDRESSREPLY] = ICMP_ADDRESS + 1
53 };
54
55 static int icmp_invert_tuple(struct nf_conntrack_tuple *tuple,
56 const struct nf_conntrack_tuple *orig)
57 {
58 if (orig->dst.u.icmp.type >= sizeof(invmap)
59 || !invmap[orig->dst.u.icmp.type])
60 return 0;
61
62 tuple->src.u.icmp.id = orig->src.u.icmp.id;
63 tuple->dst.u.icmp.type = invmap[orig->dst.u.icmp.type] - 1;
64 tuple->dst.u.icmp.code = orig->dst.u.icmp.code;
65 return 1;
66 }
67
68 /* Print out the per-protocol part of the tuple. */
69 static int icmp_print_tuple(struct seq_file *s,
70 const struct nf_conntrack_tuple *tuple)
71 {
72 return seq_printf(s, "type=%u code=%u id=%u ",
73 tuple->dst.u.icmp.type,
74 tuple->dst.u.icmp.code,
75 ntohs(tuple->src.u.icmp.id));
76 }
77
78 /* Returns verdict for packet, or -1 for invalid. */
79 static int icmp_packet(struct nf_conn *ct,
80 const struct sk_buff *skb,
81 unsigned int dataoff,
82 enum ip_conntrack_info ctinfo,
83 int pf,
84 unsigned int hooknum)
85 {
86 /* Try to delete connection immediately after all replies:
87 won't actually vanish as we still have skb, and del_timer
88 means this will only run once even if count hits zero twice
89 (theoretically possible with SMP) */
90 if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
91 if (atomic_dec_and_test(&ct->proto.icmp.count)
92 && del_timer(&ct->timeout))
93 ct->timeout.function((unsigned long)ct);
94 } else {
95 atomic_inc(&ct->proto.icmp.count);
96 nf_conntrack_event_cache(IPCT_PROTOINFO_VOLATILE, skb);
97 nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_icmp_timeout);
98 }
99
100 return NF_ACCEPT;
101 }
102
103 /* Called when a new connection for this protocol found. */
104 static int icmp_new(struct nf_conn *ct,
105 const struct sk_buff *skb, unsigned int dataoff)
106 {
107 static const u_int8_t valid_new[] = {
108 [ICMP_ECHO] = 1,
109 [ICMP_TIMESTAMP] = 1,
110 [ICMP_INFO_REQUEST] = 1,
111 [ICMP_ADDRESS] = 1
112 };
113
114 if (ct->tuplehash[0].tuple.dst.u.icmp.type >= sizeof(valid_new)
115 || !valid_new[ct->tuplehash[0].tuple.dst.u.icmp.type]) {
116 /* Can't create a new ICMP `conn' with this. */
117 pr_debug("icmp: can't create new conn with type %u\n",
118 ct->tuplehash[0].tuple.dst.u.icmp.type);
119 NF_CT_DUMP_TUPLE(&ct->tuplehash[0].tuple);
120 return 0;
121 }
122 atomic_set(&ct->proto.icmp.count, 0);
123 return 1;
124 }
125
126 /* Returns conntrack if it dealt with ICMP, and filled in skb fields */
127 static int
128 icmp_error_message(struct sk_buff *skb,
129 enum ip_conntrack_info *ctinfo,
130 unsigned int hooknum)
131 {
132 struct nf_conntrack_tuple innertuple, origtuple;
133 const struct nf_conntrack_l4proto *innerproto;
134 const struct nf_conntrack_tuple_hash *h;
135
136 NF_CT_ASSERT(skb->nfct == NULL);
137
138 /* Are they talking about one of our connections? */
139 if (!nf_ct_get_tuplepr(skb,
140 skb_network_offset(skb) + ip_hdrlen(skb)
141 + sizeof(struct icmphdr),
142 PF_INET, &origtuple)) {
143 pr_debug("icmp_error_message: failed to get tuple\n");
144 return -NF_ACCEPT;
145 }
146
147 /* rcu_read_lock()ed by nf_hook_slow */
148 innerproto = __nf_ct_l4proto_find(PF_INET, origtuple.dst.protonum);
149
150 /* Ordinarily, we'd expect the inverted tupleproto, but it's
151 been preserved inside the ICMP. */
152 if (!nf_ct_invert_tuple(&innertuple, &origtuple,
153 &nf_conntrack_l3proto_ipv4, innerproto)) {
154 pr_debug("icmp_error_message: no match\n");
155 return -NF_ACCEPT;
156 }
157
158 *ctinfo = IP_CT_RELATED;
159
160 h = nf_conntrack_find_get(&innertuple);
161 if (!h) {
162 pr_debug("icmp_error_message: no match\n");
163 return -NF_ACCEPT;
164 }
165
166 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
167 *ctinfo += IP_CT_IS_REPLY;
168
169 /* Update skb to refer to this connection */
170 skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general;
171 skb->nfctinfo = *ctinfo;
172 return -NF_ACCEPT;
173 }
174
175 /* Small and modified version of icmp_rcv */
176 static int
177 icmp_error(struct sk_buff *skb, unsigned int dataoff,
178 enum ip_conntrack_info *ctinfo, int pf, unsigned int hooknum)
179 {
180 const struct icmphdr *icmph;
181 struct icmphdr _ih;
182
183 /* Not enough header? */
184 icmph = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_ih), &_ih);
185 if (icmph == NULL) {
186 if (LOG_INVALID(IPPROTO_ICMP))
187 nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
188 "nf_ct_icmp: short packet ");
189 return -NF_ACCEPT;
190 }
191
192 /* See ip_conntrack_proto_tcp.c */
193 if (nf_conntrack_checksum && hooknum == NF_INET_PRE_ROUTING &&
194 nf_ip_checksum(skb, hooknum, dataoff, 0)) {
195 if (LOG_INVALID(IPPROTO_ICMP))
196 nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
197 "nf_ct_icmp: bad HW ICMP checksum ");
198 return -NF_ACCEPT;
199 }
200
201 /*
202 * 18 is the highest 'known' ICMP type. Anything else is a mystery
203 *
204 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
205 * discarded.
206 */
207 if (icmph->type > NR_ICMP_TYPES) {
208 if (LOG_INVALID(IPPROTO_ICMP))
209 nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
210 "nf_ct_icmp: invalid ICMP type ");
211 return -NF_ACCEPT;
212 }
213
214 /* Need to track icmp error message? */
215 if (icmph->type != ICMP_DEST_UNREACH
216 && icmph->type != ICMP_SOURCE_QUENCH
217 && icmph->type != ICMP_TIME_EXCEEDED
218 && icmph->type != ICMP_PARAMETERPROB
219 && icmph->type != ICMP_REDIRECT)
220 return NF_ACCEPT;
221
222 return icmp_error_message(skb, ctinfo, hooknum);
223 }
224
225 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
226
227 #include <linux/netfilter/nfnetlink.h>
228 #include <linux/netfilter/nfnetlink_conntrack.h>
229
230 static int icmp_tuple_to_nlattr(struct sk_buff *skb,
231 const struct nf_conntrack_tuple *t)
232 {
233 NLA_PUT_BE16(skb, CTA_PROTO_ICMP_ID, t->src.u.icmp.id);
234 NLA_PUT_U8(skb, CTA_PROTO_ICMP_TYPE, t->dst.u.icmp.type);
235 NLA_PUT_U8(skb, CTA_PROTO_ICMP_CODE, t->dst.u.icmp.code);
236
237 return 0;
238
239 nla_put_failure:
240 return -1;
241 }
242
243 static const struct nla_policy icmp_nla_policy[CTA_PROTO_MAX+1] = {
244 [CTA_PROTO_ICMP_TYPE] = { .type = NLA_U8 },
245 [CTA_PROTO_ICMP_CODE] = { .type = NLA_U8 },
246 [CTA_PROTO_ICMP_ID] = { .type = NLA_U16 },
247 };
248
249 static int icmp_nlattr_to_tuple(struct nlattr *tb[],
250 struct nf_conntrack_tuple *tuple)
251 {
252 if (!tb[CTA_PROTO_ICMP_TYPE]
253 || !tb[CTA_PROTO_ICMP_CODE]
254 || !tb[CTA_PROTO_ICMP_ID])
255 return -EINVAL;
256
257 tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMP_TYPE]);
258 tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMP_CODE]);
259 tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMP_ID]);
260
261 if (tuple->dst.u.icmp.type >= sizeof(invmap)
262 || !invmap[tuple->dst.u.icmp.type])
263 return -EINVAL;
264
265 return 0;
266 }
267 #endif
268
269 #ifdef CONFIG_SYSCTL
270 static struct ctl_table_header *icmp_sysctl_header;
271 static struct ctl_table icmp_sysctl_table[] = {
272 {
273 .procname = "nf_conntrack_icmp_timeout",
274 .data = &nf_ct_icmp_timeout,
275 .maxlen = sizeof(unsigned int),
276 .mode = 0644,
277 .proc_handler = &proc_dointvec_jiffies,
278 },
279 {
280 .ctl_name = 0
281 }
282 };
283 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
284 static struct ctl_table icmp_compat_sysctl_table[] = {
285 {
286 .procname = "ip_conntrack_icmp_timeout",
287 .data = &nf_ct_icmp_timeout,
288 .maxlen = sizeof(unsigned int),
289 .mode = 0644,
290 .proc_handler = &proc_dointvec_jiffies,
291 },
292 {
293 .ctl_name = 0
294 }
295 };
296 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
297 #endif /* CONFIG_SYSCTL */
298
299 struct nf_conntrack_l4proto nf_conntrack_l4proto_icmp __read_mostly =
300 {
301 .l3proto = PF_INET,
302 .l4proto = 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 .packet = icmp_packet,
308 .new = icmp_new,
309 .error = icmp_error,
310 .destroy = NULL,
311 .me = NULL,
312 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
313 .tuple_to_nlattr = icmp_tuple_to_nlattr,
314 .nlattr_to_tuple = icmp_nlattr_to_tuple,
315 .nla_policy = icmp_nla_policy,
316 #endif
317 #ifdef CONFIG_SYSCTL
318 .ctl_table_header = &icmp_sysctl_header,
319 .ctl_table = icmp_sysctl_table,
320 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
321 .ctl_compat_table = icmp_compat_sysctl_table,
322 #endif
323 #endif
324 };
325
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