cd0d6690627e3dd6fdc38cd96447ba8de50ce887
[linux-2.6.git] / net / ipv4 / netfilter / nf_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/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         struct icmphdr _hdr, *hp;
30
31         hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
32         if (hp == NULL)
33                 return 0;
34
35         tuple->dst.u.icmp.type = hp->type;
36         tuple->src.u.icmp.id = hp->un.echo.id;
37         tuple->dst.u.icmp.code = hp->code;
38
39         return 1;
40 }
41
42 /* Add 1; spaces filled with 0. */
43 static const u_int8_t invmap[] = {
44         [ICMP_ECHO] = ICMP_ECHOREPLY + 1,
45         [ICMP_ECHOREPLY] = ICMP_ECHO + 1,
46         [ICMP_TIMESTAMP] = ICMP_TIMESTAMPREPLY + 1,
47         [ICMP_TIMESTAMPREPLY] = ICMP_TIMESTAMP + 1,
48         [ICMP_INFO_REQUEST] = ICMP_INFO_REPLY + 1,
49         [ICMP_INFO_REPLY] = ICMP_INFO_REQUEST + 1,
50         [ICMP_ADDRESS] = ICMP_ADDRESSREPLY + 1,
51         [ICMP_ADDRESSREPLY] = ICMP_ADDRESS + 1
52 };
53
54 static int icmp_invert_tuple(struct nf_conntrack_tuple *tuple,
55                              const struct nf_conntrack_tuple *orig)
56 {
57         if (orig->dst.u.icmp.type >= sizeof(invmap)
58             || !invmap[orig->dst.u.icmp.type])
59                 return 0;
60
61         tuple->src.u.icmp.id = orig->src.u.icmp.id;
62         tuple->dst.u.icmp.type = invmap[orig->dst.u.icmp.type] - 1;
63         tuple->dst.u.icmp.code = orig->dst.u.icmp.code;
64         return 1;
65 }
66
67 /* Print out the per-protocol part of the tuple. */
68 static int icmp_print_tuple(struct seq_file *s,
69                             const struct nf_conntrack_tuple *tuple)
70 {
71         return seq_printf(s, "type=%u code=%u id=%u ",
72                           tuple->dst.u.icmp.type,
73                           tuple->dst.u.icmp.code,
74                           ntohs(tuple->src.u.icmp.id));
75 }
76
77 /* Print out the private part of the conntrack. */
78 static int icmp_print_conntrack(struct seq_file *s,
79                                 const struct nf_conn *conntrack)
80 {
81         return 0;
82 }
83
84 /* Returns verdict for packet, or -1 for invalid. */
85 static int icmp_packet(struct nf_conn *ct,
86                        const struct sk_buff *skb,
87                        unsigned int dataoff,
88                        enum ip_conntrack_info ctinfo,
89                        int pf,
90                        unsigned int hooknum)
91 {
92         /* Try to delete connection immediately after all replies:
93            won't actually vanish as we still have skb, and del_timer
94            means this will only run once even if count hits zero twice
95            (theoretically possible with SMP) */
96         if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
97                 if (atomic_dec_and_test(&ct->proto.icmp.count)
98                     && del_timer(&ct->timeout))
99                         ct->timeout.function((unsigned long)ct);
100         } else {
101                 atomic_inc(&ct->proto.icmp.count);
102                 nf_conntrack_event_cache(IPCT_PROTOINFO_VOLATILE, skb);
103                 nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_icmp_timeout);
104         }
105
106         return NF_ACCEPT;
107 }
108
109 /* Called when a new connection for this protocol found. */
110 static int icmp_new(struct nf_conn *conntrack,
111                     const struct sk_buff *skb, unsigned int dataoff)
112 {
113         static const u_int8_t valid_new[] = {
114                 [ICMP_ECHO] = 1,
115                 [ICMP_TIMESTAMP] = 1,
116                 [ICMP_INFO_REQUEST] = 1,
117                 [ICMP_ADDRESS] = 1
118         };
119
120         if (conntrack->tuplehash[0].tuple.dst.u.icmp.type >= sizeof(valid_new)
121             || !valid_new[conntrack->tuplehash[0].tuple.dst.u.icmp.type]) {
122                 /* Can't create a new ICMP `conn' with this. */
123                 pr_debug("icmp: can't create new conn with type %u\n",
124                          conntrack->tuplehash[0].tuple.dst.u.icmp.type);
125                 NF_CT_DUMP_TUPLE(&conntrack->tuplehash[0].tuple);
126                 return 0;
127         }
128         atomic_set(&conntrack->proto.icmp.count, 0);
129         return 1;
130 }
131
132 /* Returns conntrack if it dealt with ICMP, and filled in skb fields */
133 static int
134 icmp_error_message(struct sk_buff *skb,
135                  enum ip_conntrack_info *ctinfo,
136                  unsigned int hooknum)
137 {
138         struct nf_conntrack_tuple innertuple, origtuple;
139         struct nf_conntrack_l4proto *innerproto;
140         struct nf_conntrack_tuple_hash *h;
141
142         NF_CT_ASSERT(skb->nfct == NULL);
143
144         /* Are they talking about one of our connections? */
145         if (!nf_ct_get_tuplepr(skb,
146                                skb_network_offset(skb) + ip_hdrlen(skb)
147                                                        + sizeof(struct icmphdr),
148                                PF_INET, &origtuple)) {
149                 pr_debug("icmp_error_message: failed to get tuple\n");
150                 return -NF_ACCEPT;
151         }
152
153         /* rcu_read_lock()ed by nf_hook_slow */
154         innerproto = __nf_ct_l4proto_find(PF_INET, origtuple.dst.protonum);
155
156         /* Ordinarily, we'd expect the inverted tupleproto, but it's
157            been preserved inside the ICMP. */
158         if (!nf_ct_invert_tuple(&innertuple, &origtuple,
159                                 &nf_conntrack_l3proto_ipv4, innerproto)) {
160                 pr_debug("icmp_error_message: no match\n");
161                 return -NF_ACCEPT;
162         }
163
164         *ctinfo = IP_CT_RELATED;
165
166         h = nf_conntrack_find_get(&innertuple);
167         if (!h) {
168                 pr_debug("icmp_error_message: no match\n");
169                 return -NF_ACCEPT;
170         }
171
172         if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
173                 *ctinfo += IP_CT_IS_REPLY;
174
175         /* Update skb to refer to this connection */
176         skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general;
177         skb->nfctinfo = *ctinfo;
178         return -NF_ACCEPT;
179 }
180
181 /* Small and modified version of icmp_rcv */
182 static int
183 icmp_error(struct sk_buff *skb, unsigned int dataoff,
184            enum ip_conntrack_info *ctinfo, int pf, unsigned int hooknum)
185 {
186         struct icmphdr _ih, *icmph;
187
188         /* Not enough header? */
189         icmph = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_ih), &_ih);
190         if (icmph == NULL) {
191                 if (LOG_INVALID(IPPROTO_ICMP))
192                         nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
193                                       "nf_ct_icmp: short packet ");
194                 return -NF_ACCEPT;
195         }
196
197         /* See ip_conntrack_proto_tcp.c */
198         if (nf_conntrack_checksum && hooknum == NF_INET_PRE_ROUTING &&
199             nf_ip_checksum(skb, hooknum, dataoff, 0)) {
200                 if (LOG_INVALID(IPPROTO_ICMP))
201                         nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
202                                       "nf_ct_icmp: bad HW ICMP checksum ");
203                 return -NF_ACCEPT;
204         }
205
206         /*
207          *      18 is the highest 'known' ICMP type. Anything else is a mystery
208          *
209          *      RFC 1122: 3.2.2  Unknown ICMP messages types MUST be silently
210          *                discarded.
211          */
212         if (icmph->type > NR_ICMP_TYPES) {
213                 if (LOG_INVALID(IPPROTO_ICMP))
214                         nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
215                                       "nf_ct_icmp: invalid ICMP type ");
216                 return -NF_ACCEPT;
217         }
218
219         /* Need to track icmp error message? */
220         if (icmph->type != ICMP_DEST_UNREACH
221             && icmph->type != ICMP_SOURCE_QUENCH
222             && icmph->type != ICMP_TIME_EXCEEDED
223             && icmph->type != ICMP_PARAMETERPROB
224             && icmph->type != ICMP_REDIRECT)
225                 return NF_ACCEPT;
226
227         return icmp_error_message(skb, ctinfo, hooknum);
228 }
229
230 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
231
232 #include <linux/netfilter/nfnetlink.h>
233 #include <linux/netfilter/nfnetlink_conntrack.h>
234
235 static int icmp_tuple_to_nlattr(struct sk_buff *skb,
236                                 const struct nf_conntrack_tuple *t)
237 {
238         NLA_PUT_BE16(skb, CTA_PROTO_ICMP_ID, t->src.u.icmp.id);
239         NLA_PUT_U8(skb, CTA_PROTO_ICMP_TYPE, t->dst.u.icmp.type);
240         NLA_PUT_U8(skb, CTA_PROTO_ICMP_CODE, t->dst.u.icmp.code);
241
242         return 0;
243
244 nla_put_failure:
245         return -1;
246 }
247
248 static const struct nla_policy icmp_nla_policy[CTA_PROTO_MAX+1] = {
249         [CTA_PROTO_ICMP_TYPE]   = { .type = NLA_U8 },
250         [CTA_PROTO_ICMP_CODE]   = { .type = NLA_U8 },
251         [CTA_PROTO_ICMP_ID]     = { .type = NLA_U16 },
252 };
253
254 static int icmp_nlattr_to_tuple(struct nlattr *tb[],
255                                 struct nf_conntrack_tuple *tuple)
256 {
257         if (!tb[CTA_PROTO_ICMP_TYPE]
258             || !tb[CTA_PROTO_ICMP_CODE]
259             || !tb[CTA_PROTO_ICMP_ID])
260                 return -EINVAL;
261
262         tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMP_TYPE]);
263         tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMP_CODE]);
264         tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMP_ID]);
265
266         if (tuple->dst.u.icmp.type >= sizeof(invmap)
267             || !invmap[tuple->dst.u.icmp.type])
268                 return -EINVAL;
269
270         return 0;
271 }
272 #endif
273
274 #ifdef CONFIG_SYSCTL
275 static struct ctl_table_header *icmp_sysctl_header;
276 static struct ctl_table icmp_sysctl_table[] = {
277         {
278                 .procname       = "nf_conntrack_icmp_timeout",
279                 .data           = &nf_ct_icmp_timeout,
280                 .maxlen         = sizeof(unsigned int),
281                 .mode           = 0644,
282                 .proc_handler   = &proc_dointvec_jiffies,
283         },
284         {
285                 .ctl_name = 0
286         }
287 };
288 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
289 static struct ctl_table icmp_compat_sysctl_table[] = {
290         {
291                 .procname       = "ip_conntrack_icmp_timeout",
292                 .data           = &nf_ct_icmp_timeout,
293                 .maxlen         = sizeof(unsigned int),
294                 .mode           = 0644,
295                 .proc_handler   = &proc_dointvec_jiffies,
296         },
297         {
298                 .ctl_name = 0
299         }
300 };
301 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
302 #endif /* CONFIG_SYSCTL */
303
304 struct nf_conntrack_l4proto nf_conntrack_l4proto_icmp __read_mostly =
305 {
306         .l3proto                = PF_INET,
307         .l4proto                = IPPROTO_ICMP,
308         .name                   = "icmp",
309         .pkt_to_tuple           = icmp_pkt_to_tuple,
310         .invert_tuple           = icmp_invert_tuple,
311         .print_tuple            = icmp_print_tuple,
312         .print_conntrack        = icmp_print_conntrack,
313         .packet                 = icmp_packet,
314         .new                    = icmp_new,
315         .error                  = icmp_error,
316         .destroy                = NULL,
317         .me                     = NULL,
318 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
319         .tuple_to_nlattr        = icmp_tuple_to_nlattr,
320         .nlattr_to_tuple        = icmp_nlattr_to_tuple,
321         .nla_policy             = icmp_nla_policy,
322 #endif
323 #ifdef CONFIG_SYSCTL
324         .ctl_table_header       = &icmp_sysctl_header,
325         .ctl_table              = icmp_sysctl_table,
326 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
327         .ctl_compat_table       = icmp_compat_sysctl_table,
328 #endif
329 #endif
330 };