2a8bee26f43d9dcb58079a291a69264455342b22
[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 int nf_ct_icmp_timeout __read_mostly = 30*HZ;
24
25 static bool icmp_pkt_to_tuple(const struct sk_buff *skb, unsigned int dataoff,
26                               struct nf_conntrack_tuple *tuple)
27 {
28         const struct icmphdr *hp;
29         struct icmphdr _hdr;
30
31         hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
32         if (hp == NULL)
33                 return false;
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 true;
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 bool 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 false;
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 true;
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 /* Returns verdict for packet, or -1 for invalid. */
78 static int icmp_packet(struct nf_conn *ct,
79                        const struct sk_buff *skb,
80                        unsigned int dataoff,
81                        enum ip_conntrack_info ctinfo,
82                        u_int8_t pf,
83                        unsigned int hooknum)
84 {
85         /* Try to delete connection immediately after all replies:
86            won't actually vanish as we still have skb, and del_timer
87            means this will only run once even if count hits zero twice
88            (theoretically possible with SMP) */
89         if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
90                 if (atomic_dec_and_test(&ct->proto.icmp.count))
91                         nf_ct_kill_acct(ct, ctinfo, skb);
92         } else {
93                 atomic_inc(&ct->proto.icmp.count);
94                 nf_conntrack_event_cache(IPCT_PROTOINFO_VOLATILE, ct);
95                 nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_icmp_timeout);
96         }
97
98         return NF_ACCEPT;
99 }
100
101 /* Called when a new connection for this protocol found. */
102 static bool icmp_new(struct nf_conn *ct, const struct sk_buff *skb,
103                      unsigned int dataoff)
104 {
105         static const u_int8_t valid_new[] = {
106                 [ICMP_ECHO] = 1,
107                 [ICMP_TIMESTAMP] = 1,
108                 [ICMP_INFO_REQUEST] = 1,
109                 [ICMP_ADDRESS] = 1
110         };
111
112         if (ct->tuplehash[0].tuple.dst.u.icmp.type >= sizeof(valid_new)
113             || !valid_new[ct->tuplehash[0].tuple.dst.u.icmp.type]) {
114                 /* Can't create a new ICMP `conn' with this. */
115                 pr_debug("icmp: can't create new conn with type %u\n",
116                          ct->tuplehash[0].tuple.dst.u.icmp.type);
117                 nf_ct_dump_tuple_ip(&ct->tuplehash[0].tuple);
118                 return false;
119         }
120         atomic_set(&ct->proto.icmp.count, 0);
121         return true;
122 }
123
124 /* Returns conntrack if it dealt with ICMP, and filled in skb fields */
125 static int
126 icmp_error_message(struct net *net, struct sk_buff *skb,
127                  enum ip_conntrack_info *ctinfo,
128                  unsigned int hooknum)
129 {
130         struct nf_conntrack_tuple innertuple, origtuple;
131         const struct nf_conntrack_l4proto *innerproto;
132         const struct nf_conntrack_tuple_hash *h;
133
134         NF_CT_ASSERT(skb->nfct == NULL);
135
136         /* Are they talking about one of our connections? */
137         if (!nf_ct_get_tuplepr(skb,
138                                skb_network_offset(skb) + ip_hdrlen(skb)
139                                                        + sizeof(struct icmphdr),
140                                PF_INET, &origtuple)) {
141                 pr_debug("icmp_error_message: failed to get tuple\n");
142                 return -NF_ACCEPT;
143         }
144
145         /* rcu_read_lock()ed by nf_hook_slow */
146         innerproto = __nf_ct_l4proto_find(PF_INET, origtuple.dst.protonum);
147
148         /* Ordinarily, we'd expect the inverted tupleproto, but it's
149            been preserved inside the ICMP. */
150         if (!nf_ct_invert_tuple(&innertuple, &origtuple,
151                                 &nf_conntrack_l3proto_ipv4, innerproto)) {
152                 pr_debug("icmp_error_message: no match\n");
153                 return -NF_ACCEPT;
154         }
155
156         *ctinfo = IP_CT_RELATED;
157
158         h = nf_conntrack_find_get(net, &innertuple);
159         if (!h) {
160                 pr_debug("icmp_error_message: no match\n");
161                 return -NF_ACCEPT;
162         }
163
164         if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
165                 *ctinfo += IP_CT_IS_REPLY;
166
167         /* Update skb to refer to this connection */
168         skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general;
169         skb->nfctinfo = *ctinfo;
170         return -NF_ACCEPT;
171 }
172
173 /* Small and modified version of icmp_rcv */
174 static int
175 icmp_error(struct net *net, struct sk_buff *skb, unsigned int dataoff,
176            enum ip_conntrack_info *ctinfo, u_int8_t pf, unsigned int hooknum)
177 {
178         const struct icmphdr *icmph;
179         struct icmphdr _ih;
180
181         /* Not enough header? */
182         icmph = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_ih), &_ih);
183         if (icmph == NULL) {
184                 if (LOG_INVALID(net, IPPROTO_ICMP))
185                         nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
186                                       "nf_ct_icmp: short packet ");
187                 return -NF_ACCEPT;
188         }
189
190         /* See ip_conntrack_proto_tcp.c */
191         if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
192             nf_ip_checksum(skb, hooknum, dataoff, 0)) {
193                 if (LOG_INVALID(net, IPPROTO_ICMP))
194                         nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
195                                       "nf_ct_icmp: bad HW ICMP checksum ");
196                 return -NF_ACCEPT;
197         }
198
199         /*
200          *      18 is the highest 'known' ICMP type. Anything else is a mystery
201          *
202          *      RFC 1122: 3.2.2  Unknown ICMP messages types MUST be silently
203          *                discarded.
204          */
205         if (icmph->type > NR_ICMP_TYPES) {
206                 if (LOG_INVALID(net, IPPROTO_ICMP))
207                         nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
208                                       "nf_ct_icmp: invalid ICMP type ");
209                 return -NF_ACCEPT;
210         }
211
212         /* Need to track icmp error message? */
213         if (icmph->type != ICMP_DEST_UNREACH
214             && icmph->type != ICMP_SOURCE_QUENCH
215             && icmph->type != ICMP_TIME_EXCEEDED
216             && icmph->type != ICMP_PARAMETERPROB
217             && icmph->type != ICMP_REDIRECT)
218                 return NF_ACCEPT;
219
220         return icmp_error_message(net, skb, ctinfo, hooknum);
221 }
222
223 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
224
225 #include <linux/netfilter/nfnetlink.h>
226 #include <linux/netfilter/nfnetlink_conntrack.h>
227
228 static int icmp_tuple_to_nlattr(struct sk_buff *skb,
229                                 const struct nf_conntrack_tuple *t)
230 {
231         NLA_PUT_BE16(skb, CTA_PROTO_ICMP_ID, t->src.u.icmp.id);
232         NLA_PUT_U8(skb, CTA_PROTO_ICMP_TYPE, t->dst.u.icmp.type);
233         NLA_PUT_U8(skb, CTA_PROTO_ICMP_CODE, t->dst.u.icmp.code);
234
235         return 0;
236
237 nla_put_failure:
238         return -1;
239 }
240
241 static const struct nla_policy icmp_nla_policy[CTA_PROTO_MAX+1] = {
242         [CTA_PROTO_ICMP_TYPE]   = { .type = NLA_U8 },
243         [CTA_PROTO_ICMP_CODE]   = { .type = NLA_U8 },
244         [CTA_PROTO_ICMP_ID]     = { .type = NLA_U16 },
245 };
246
247 static int icmp_nlattr_to_tuple(struct nlattr *tb[],
248                                 struct nf_conntrack_tuple *tuple)
249 {
250         if (!tb[CTA_PROTO_ICMP_TYPE]
251             || !tb[CTA_PROTO_ICMP_CODE]
252             || !tb[CTA_PROTO_ICMP_ID])
253                 return -EINVAL;
254
255         tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMP_TYPE]);
256         tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMP_CODE]);
257         tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMP_ID]);
258
259         if (tuple->dst.u.icmp.type >= sizeof(invmap)
260             || !invmap[tuple->dst.u.icmp.type])
261                 return -EINVAL;
262
263         return 0;
264 }
265 #endif
266
267 #ifdef CONFIG_SYSCTL
268 static struct ctl_table_header *icmp_sysctl_header;
269 static struct ctl_table icmp_sysctl_table[] = {
270         {
271                 .procname       = "nf_conntrack_icmp_timeout",
272                 .data           = &nf_ct_icmp_timeout,
273                 .maxlen         = sizeof(unsigned int),
274                 .mode           = 0644,
275                 .proc_handler   = proc_dointvec_jiffies,
276         },
277         {
278                 .ctl_name = 0
279         }
280 };
281 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
282 static struct ctl_table icmp_compat_sysctl_table[] = {
283         {
284                 .procname       = "ip_conntrack_icmp_timeout",
285                 .data           = &nf_ct_icmp_timeout,
286                 .maxlen         = sizeof(unsigned int),
287                 .mode           = 0644,
288                 .proc_handler   = proc_dointvec_jiffies,
289         },
290         {
291                 .ctl_name = 0
292         }
293 };
294 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
295 #endif /* CONFIG_SYSCTL */
296
297 struct nf_conntrack_l4proto nf_conntrack_l4proto_icmp __read_mostly =
298 {
299         .l3proto                = PF_INET,
300         .l4proto                = IPPROTO_ICMP,
301         .name                   = "icmp",
302         .pkt_to_tuple           = icmp_pkt_to_tuple,
303         .invert_tuple           = icmp_invert_tuple,
304         .print_tuple            = icmp_print_tuple,
305         .packet                 = icmp_packet,
306         .new                    = icmp_new,
307         .error                  = icmp_error,
308         .destroy                = NULL,
309         .me                     = NULL,
310 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
311         .tuple_to_nlattr        = icmp_tuple_to_nlattr,
312         .nlattr_to_tuple        = icmp_nlattr_to_tuple,
313         .nla_policy             = icmp_nla_policy,
314 #endif
315 #ifdef CONFIG_SYSCTL
316         .ctl_table_header       = &icmp_sysctl_header,
317         .ctl_table              = icmp_sysctl_table,
318 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
319         .ctl_compat_table       = icmp_compat_sysctl_table,
320 #endif
321 #endif
322 };