net: '&' redux
[deliverable/linux.git] / net / ipv4 / netfilter / nf_conntrack_proto_icmp.c
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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.
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7 */
8
9#include <linux/types.h>
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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>
605dcad6 19#include <net/netfilter/nf_conntrack_l4proto.h>
9fb9cbb1 20#include <net/netfilter/nf_conntrack_core.h>
f01ffbd6 21#include <net/netfilter/nf_log.h>
9fb9cbb1 22
933a41e7 23static unsigned long nf_ct_icmp_timeout __read_mostly = 30*HZ;
9fb9cbb1 24
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25static bool icmp_pkt_to_tuple(const struct sk_buff *skb, unsigned int dataoff,
26 struct nf_conntrack_tuple *tuple)
9fb9cbb1 27{
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28 const struct icmphdr *hp;
29 struct icmphdr _hdr;
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30
31 hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
32 if (hp == NULL)
09f263cd 33 return false;
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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
09f263cd 39 return true;
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40}
41
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42/* Add 1; spaces filled with 0. */
43static 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
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54static bool icmp_invert_tuple(struct nf_conntrack_tuple *tuple,
55 const struct nf_conntrack_tuple *orig)
9fb9cbb1 56{
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57 if (orig->dst.u.icmp.type >= sizeof(invmap)
58 || !invmap[orig->dst.u.icmp.type])
09f263cd 59 return false;
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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;
09f263cd 64 return true;
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65}
66
67/* Print out the per-protocol part of the tuple. */
68static 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
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77/* Returns verdict for packet, or -1 for invalid. */
78static int icmp_packet(struct nf_conn *ct,
79 const struct sk_buff *skb,
80 unsigned int dataoff,
81 enum ip_conntrack_info ctinfo,
76108cea 82 u_int8_t pf,
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83 unsigned int hooknum)
84{
85 /* Try to delete connection immediately after all replies:
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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) */
9fb9cbb1 89 if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
51091764 90 if (atomic_dec_and_test(&ct->proto.icmp.count))
718d4ad9 91 nf_ct_kill_acct(ct, ctinfo, skb);
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92 } else {
93 atomic_inc(&ct->proto.icmp.count);
a71996fc 94 nf_conntrack_event_cache(IPCT_PROTOINFO_VOLATILE, ct);
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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. */
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102static bool icmp_new(struct nf_conn *ct, const struct sk_buff *skb,
103 unsigned int dataoff)
9fb9cbb1 104{
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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 };
9fb9cbb1 111
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112 if (ct->tuplehash[0].tuple.dst.u.icmp.type >= sizeof(valid_new)
113 || !valid_new[ct->tuplehash[0].tuple.dst.u.icmp.type]) {
9fb9cbb1 114 /* Can't create a new ICMP `conn' with this. */
0d53778e 115 pr_debug("icmp: can't create new conn with type %u\n",
c88130bc 116 ct->tuplehash[0].tuple.dst.u.icmp.type);
3c9fba65 117 nf_ct_dump_tuple_ip(&ct->tuplehash[0].tuple);
09f263cd 118 return false;
9fb9cbb1 119 }
c88130bc 120 atomic_set(&ct->proto.icmp.count, 0);
09f263cd 121 return true;
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122}
123
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124/* Returns conntrack if it dealt with ICMP, and filled in skb fields */
125static int
74c51a14 126icmp_error_message(struct net *net, struct sk_buff *skb,
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127 enum ip_conntrack_info *ctinfo,
128 unsigned int hooknum)
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129{
130 struct nf_conntrack_tuple innertuple, origtuple;
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131 const struct nf_conntrack_l4proto *innerproto;
132 const struct nf_conntrack_tuple_hash *h;
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133
134 NF_CT_ASSERT(skb->nfct == NULL);
135
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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");
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142 return -NF_ACCEPT;
143 }
144
923f4902 145 /* rcu_read_lock()ed by nf_hook_slow */
e2a3123f 146 innerproto = __nf_ct_l4proto_find(PF_INET, origtuple.dst.protonum);
9fb9cbb1 147
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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,
9fb9cbb1 151 &nf_conntrack_l3proto_ipv4, innerproto)) {
0d53778e 152 pr_debug("icmp_error_message: no match\n");
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153 return -NF_ACCEPT;
154 }
155
156 *ctinfo = IP_CT_RELATED;
157
74c51a14 158 h = nf_conntrack_find_get(net, &innertuple);
9fb9cbb1 159 if (!h) {
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160 pr_debug("icmp_error_message: no match\n");
161 return -NF_ACCEPT;
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162 }
163
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164 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
165 *ctinfo += IP_CT_IS_REPLY;
166
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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;
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171}
172
173/* Small and modified version of icmp_rcv */
174static int
74c51a14 175icmp_error(struct net *net, struct sk_buff *skb, unsigned int dataoff,
76108cea 176 enum ip_conntrack_info *ctinfo, u_int8_t pf, unsigned int hooknum)
9fb9cbb1 177{
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178 const struct icmphdr *icmph;
179 struct icmphdr _ih;
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180
181 /* Not enough header? */
c9bdd4b5 182 icmph = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_ih), &_ih);
9fb9cbb1 183 if (icmph == NULL) {
c2a2c7e0 184 if (LOG_INVALID(net, IPPROTO_ICMP))
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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 */
c04d0552 191 if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
96f6bf82 192 nf_ip_checksum(skb, hooknum, dataoff, 0)) {
c2a2c7e0 193 if (LOG_INVALID(net, IPPROTO_ICMP))
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194 nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
195 "nf_ct_icmp: bad HW ICMP checksum ");
196 return -NF_ACCEPT;
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197 }
198
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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) {
c2a2c7e0 206 if (LOG_INVALID(net, IPPROTO_ICMP))
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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
74c51a14 220 return icmp_error_message(net, skb, ctinfo, hooknum);
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221}
222
e281db5c 223#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
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224
225#include <linux/netfilter/nfnetlink.h>
226#include <linux/netfilter/nfnetlink_conntrack.h>
227
fdf70832 228static int icmp_tuple_to_nlattr(struct sk_buff *skb,
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229 const struct nf_conntrack_tuple *t)
230{
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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);
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234
235 return 0;
236
df6fb868 237nla_put_failure:
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238 return -1;
239}
240
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241static 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 },
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245};
246
fdf70832 247static int icmp_nlattr_to_tuple(struct nlattr *tb[],
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248 struct nf_conntrack_tuple *tuple)
249{
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250 if (!tb[CTA_PROTO_ICMP_TYPE]
251 || !tb[CTA_PROTO_ICMP_CODE]
252 || !tb[CTA_PROTO_ICMP_ID])
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253 return -EINVAL;
254
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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]);
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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
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267#ifdef CONFIG_SYSCTL
268static struct ctl_table_header *icmp_sysctl_header;
269static struct ctl_table icmp_sysctl_table[] = {
270 {
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271 .procname = "nf_conntrack_icmp_timeout",
272 .data = &nf_ct_icmp_timeout,
273 .maxlen = sizeof(unsigned int),
274 .mode = 0644,
6d9f239a 275 .proc_handler = proc_dointvec_jiffies,
933a41e7 276 },
e905a9ed 277 {
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278 .ctl_name = 0
279 }
280};
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281#ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
282static struct ctl_table icmp_compat_sysctl_table[] = {
283 {
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284 .procname = "ip_conntrack_icmp_timeout",
285 .data = &nf_ct_icmp_timeout,
286 .maxlen = sizeof(unsigned int),
287 .mode = 0644,
6d9f239a 288 .proc_handler = proc_dointvec_jiffies,
a999e683 289 },
e905a9ed 290 {
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291 .ctl_name = 0
292 }
293};
294#endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
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295#endif /* CONFIG_SYSCTL */
296
61075af5 297struct nf_conntrack_l4proto nf_conntrack_l4proto_icmp __read_mostly =
9fb9cbb1 298{
9fb9cbb1 299 .l3proto = PF_INET,
605dcad6 300 .l4proto = IPPROTO_ICMP,
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301 .name = "icmp",
302 .pkt_to_tuple = icmp_pkt_to_tuple,
303 .invert_tuple = icmp_invert_tuple,
304 .print_tuple = icmp_print_tuple,
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305 .packet = icmp_packet,
306 .new = icmp_new,
307 .error = icmp_error,
308 .destroy = NULL,
c1d10adb 309 .me = NULL,
e281db5c 310#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
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311 .tuple_to_nlattr = icmp_tuple_to_nlattr,
312 .nlattr_to_tuple = icmp_nlattr_to_tuple,
f73e924c 313 .nla_policy = icmp_nla_policy,
c1d10adb 314#endif
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315#ifdef CONFIG_SYSCTL
316 .ctl_table_header = &icmp_sysctl_header,
317 .ctl_table = icmp_sysctl_table,
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318#ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
319 .ctl_compat_table = icmp_compat_sysctl_table,
320#endif
933a41e7 321#endif
9fb9cbb1 322};
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