1 /* (C) 1999-2001 Paul `Rusty' Russell
2 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
3 * (C) 2006-2010 Patrick McHardy <kaber@trash.net>
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
8 */
9
10 #include <linux/types.h>
11 #include <linux/timer.h>
12 #include <linux/netfilter.h>
13 #include <linux/in.h>
14 #include <linux/icmp.h>
15 #include <linux/seq_file.h>
16 #include <net/ip.h>
17 #include <net/checksum.h>
18 #include <linux/netfilter_ipv4.h>
19 #include <net/netfilter/nf_conntrack_tuple.h>
20 #include <net/netfilter/nf_conntrack_l4proto.h>
21 #include <net/netfilter/nf_conntrack_core.h>
22 #include <net/netfilter/nf_conntrack_zones.h>
23 #include <net/netfilter/nf_log.h>
24
25 static unsigned int nf_ct_icmp_timeout __read_mostly = 30*HZ;
26
icmp_pernet(struct net * net)27 static inline struct nf_icmp_net *icmp_pernet(struct net *net)
28 {
29 return &net->ct.nf_ct_proto.icmp;
30 }
31
icmp_pkt_to_tuple(const struct sk_buff * skb,unsigned int dataoff,struct net * net,struct nf_conntrack_tuple * tuple)32 static bool icmp_pkt_to_tuple(const struct sk_buff *skb, unsigned int dataoff,
33 struct net *net, struct nf_conntrack_tuple *tuple)
34 {
35 const struct icmphdr *hp;
36 struct icmphdr _hdr;
37
38 hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
39 if (hp == NULL)
40 return false;
41
42 tuple->dst.u.icmp.type = hp->type;
43 tuple->src.u.icmp.id = hp->un.echo.id;
44 tuple->dst.u.icmp.code = hp->code;
45
46 return true;
47 }
48
49 /* Add 1; spaces filled with 0. */
50 static const u_int8_t invmap[] = {
51 [ICMP_ECHO] = ICMP_ECHOREPLY + 1,
52 [ICMP_ECHOREPLY] = ICMP_ECHO + 1,
53 [ICMP_TIMESTAMP] = ICMP_TIMESTAMPREPLY + 1,
54 [ICMP_TIMESTAMPREPLY] = ICMP_TIMESTAMP + 1,
55 [ICMP_INFO_REQUEST] = ICMP_INFO_REPLY + 1,
56 [ICMP_INFO_REPLY] = ICMP_INFO_REQUEST + 1,
57 [ICMP_ADDRESS] = ICMP_ADDRESSREPLY + 1,
58 [ICMP_ADDRESSREPLY] = ICMP_ADDRESS + 1
59 };
60
icmp_invert_tuple(struct nf_conntrack_tuple * tuple,const struct nf_conntrack_tuple * orig)61 static bool icmp_invert_tuple(struct nf_conntrack_tuple *tuple,
62 const struct nf_conntrack_tuple *orig)
63 {
64 if (orig->dst.u.icmp.type >= sizeof(invmap) ||
65 !invmap[orig->dst.u.icmp.type])
66 return false;
67
68 tuple->src.u.icmp.id = orig->src.u.icmp.id;
69 tuple->dst.u.icmp.type = invmap[orig->dst.u.icmp.type] - 1;
70 tuple->dst.u.icmp.code = orig->dst.u.icmp.code;
71 return true;
72 }
73
74 /* Print out the per-protocol part of the tuple. */
icmp_print_tuple(struct seq_file * s,const struct nf_conntrack_tuple * tuple)75 static void icmp_print_tuple(struct seq_file *s,
76 const struct nf_conntrack_tuple *tuple)
77 {
78 seq_printf(s, "type=%u code=%u id=%u ",
79 tuple->dst.u.icmp.type,
80 tuple->dst.u.icmp.code,
81 ntohs(tuple->src.u.icmp.id));
82 }
83
icmp_get_timeouts(struct net * net)84 static unsigned int *icmp_get_timeouts(struct net *net)
85 {
86 return &icmp_pernet(net)->timeout;
87 }
88
89 /* Returns verdict for packet, or -1 for invalid. */
icmp_packet(struct nf_conn * ct,const struct sk_buff * skb,unsigned int dataoff,enum ip_conntrack_info ctinfo,u_int8_t pf,unsigned int hooknum,unsigned int * timeout)90 static int icmp_packet(struct nf_conn *ct,
91 const struct sk_buff *skb,
92 unsigned int dataoff,
93 enum ip_conntrack_info ctinfo,
94 u_int8_t pf,
95 unsigned int hooknum,
96 unsigned int *timeout)
97 {
98 /* Do not immediately delete the connection after the first
99 successful reply to avoid excessive conntrackd traffic
100 and also to handle correctly ICMP echo reply duplicates. */
101 nf_ct_refresh_acct(ct, ctinfo, skb, *timeout);
102
103 return NF_ACCEPT;
104 }
105
106 /* Called when a new connection for this protocol found. */
icmp_new(struct nf_conn * ct,const struct sk_buff * skb,unsigned int dataoff,unsigned int * timeouts)107 static bool icmp_new(struct nf_conn *ct, const struct sk_buff *skb,
108 unsigned int dataoff, unsigned int *timeouts)
109 {
110 static const u_int8_t valid_new[] = {
111 [ICMP_ECHO] = 1,
112 [ICMP_TIMESTAMP] = 1,
113 [ICMP_INFO_REQUEST] = 1,
114 [ICMP_ADDRESS] = 1
115 };
116
117 if (ct->tuplehash[0].tuple.dst.u.icmp.type >= sizeof(valid_new) ||
118 !valid_new[ct->tuplehash[0].tuple.dst.u.icmp.type]) {
119 /* Can't create a new ICMP `conn' with this. */
120 pr_debug("icmp: can't create new conn with type %u\n",
121 ct->tuplehash[0].tuple.dst.u.icmp.type);
122 nf_ct_dump_tuple_ip(&ct->tuplehash[0].tuple);
123 return false;
124 }
125 return true;
126 }
127
128 /* Returns conntrack if it dealt with ICMP, and filled in skb fields */
129 static int
icmp_error_message(struct net * net,struct nf_conn * tmpl,struct sk_buff * skb,enum ip_conntrack_info * ctinfo,unsigned int hooknum)130 icmp_error_message(struct net *net, struct nf_conn *tmpl, struct sk_buff *skb,
131 enum ip_conntrack_info *ctinfo,
132 unsigned int hooknum)
133 {
134 struct nf_conntrack_tuple innertuple, origtuple;
135 const struct nf_conntrack_l4proto *innerproto;
136 const struct nf_conntrack_tuple_hash *h;
137 const struct nf_conntrack_zone *zone;
138 struct nf_conntrack_zone tmp;
139
140 NF_CT_ASSERT(skb->nfct == NULL);
141 zone = nf_ct_zone_tmpl(tmpl, skb, &tmp);
142
143 /* Are they talking about one of our connections? */
144 if (!nf_ct_get_tuplepr(skb,
145 skb_network_offset(skb) + ip_hdrlen(skb)
146 + sizeof(struct icmphdr),
147 PF_INET, net, &origtuple)) {
148 pr_debug("icmp_error_message: failed to get tuple\n");
149 return -NF_ACCEPT;
150 }
151
152 /* rcu_read_lock()ed by nf_hook_slow */
153 innerproto = __nf_ct_l4proto_find(PF_INET, origtuple.dst.protonum);
154
155 /* Ordinarily, we'd expect the inverted tupleproto, but it's
156 been preserved inside the ICMP. */
157 if (!nf_ct_invert_tuple(&innertuple, &origtuple,
158 &nf_conntrack_l3proto_ipv4, innerproto)) {
159 pr_debug("icmp_error_message: no match\n");
160 return -NF_ACCEPT;
161 }
162
163 *ctinfo = IP_CT_RELATED;
164
165 h = nf_conntrack_find_get(net, zone, &innertuple);
166 if (!h) {
167 pr_debug("icmp_error_message: no match\n");
168 return -NF_ACCEPT;
169 }
170
171 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
172 *ctinfo += IP_CT_IS_REPLY;
173
174 /* Update skb to refer to this connection */
175 skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general;
176 skb->nfctinfo = *ctinfo;
177 return NF_ACCEPT;
178 }
179
180 /* Small and modified version of icmp_rcv */
181 static int
icmp_error(struct net * net,struct nf_conn * tmpl,struct sk_buff * skb,unsigned int dataoff,enum ip_conntrack_info * ctinfo,u_int8_t pf,unsigned int hooknum)182 icmp_error(struct net *net, struct nf_conn *tmpl,
183 struct sk_buff *skb, unsigned int dataoff,
184 enum ip_conntrack_info *ctinfo, u_int8_t pf, unsigned int hooknum)
185 {
186 const struct icmphdr *icmph;
187 struct icmphdr _ih;
188
189 /* Not enough header? */
190 icmph = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_ih), &_ih);
191 if (icmph == NULL) {
192 if (LOG_INVALID(net, IPPROTO_ICMP))
193 nf_log_packet(net, PF_INET, 0, skb, NULL, NULL,
194 NULL, "nf_ct_icmp: short packet ");
195 return -NF_ACCEPT;
196 }
197
198 /* See ip_conntrack_proto_tcp.c */
199 if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
200 nf_ip_checksum(skb, hooknum, dataoff, 0)) {
201 if (LOG_INVALID(net, IPPROTO_ICMP))
202 nf_log_packet(net, PF_INET, 0, skb, NULL, NULL, NULL,
203 "nf_ct_icmp: bad HW ICMP checksum ");
204 return -NF_ACCEPT;
205 }
206
207 /*
208 * 18 is the highest 'known' ICMP type. Anything else is a mystery
209 *
210 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
211 * discarded.
212 */
213 if (icmph->type > NR_ICMP_TYPES) {
214 if (LOG_INVALID(net, IPPROTO_ICMP))
215 nf_log_packet(net, PF_INET, 0, skb, NULL, NULL, NULL,
216 "nf_ct_icmp: invalid ICMP type ");
217 return -NF_ACCEPT;
218 }
219
220 /* Need to track icmp error message? */
221 if (icmph->type != ICMP_DEST_UNREACH &&
222 icmph->type != ICMP_SOURCE_QUENCH &&
223 icmph->type != ICMP_TIME_EXCEEDED &&
224 icmph->type != ICMP_PARAMETERPROB &&
225 icmph->type != ICMP_REDIRECT)
226 return NF_ACCEPT;
227
228 return icmp_error_message(net, tmpl, skb, ctinfo, hooknum);
229 }
230
231 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
232
233 #include <linux/netfilter/nfnetlink.h>
234 #include <linux/netfilter/nfnetlink_conntrack.h>
235
icmp_tuple_to_nlattr(struct sk_buff * skb,const struct nf_conntrack_tuple * t)236 static int icmp_tuple_to_nlattr(struct sk_buff *skb,
237 const struct nf_conntrack_tuple *t)
238 {
239 if (nla_put_be16(skb, CTA_PROTO_ICMP_ID, t->src.u.icmp.id) ||
240 nla_put_u8(skb, CTA_PROTO_ICMP_TYPE, t->dst.u.icmp.type) ||
241 nla_put_u8(skb, CTA_PROTO_ICMP_CODE, t->dst.u.icmp.code))
242 goto nla_put_failure;
243 return 0;
244
245 nla_put_failure:
246 return -1;
247 }
248
249 static const struct nla_policy icmp_nla_policy[CTA_PROTO_MAX+1] = {
250 [CTA_PROTO_ICMP_TYPE] = { .type = NLA_U8 },
251 [CTA_PROTO_ICMP_CODE] = { .type = NLA_U8 },
252 [CTA_PROTO_ICMP_ID] = { .type = NLA_U16 },
253 };
254
icmp_nlattr_to_tuple(struct nlattr * tb[],struct nf_conntrack_tuple * tuple)255 static int icmp_nlattr_to_tuple(struct nlattr *tb[],
256 struct nf_conntrack_tuple *tuple)
257 {
258 if (!tb[CTA_PROTO_ICMP_TYPE] ||
259 !tb[CTA_PROTO_ICMP_CODE] ||
260 !tb[CTA_PROTO_ICMP_ID])
261 return -EINVAL;
262
263 tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMP_TYPE]);
264 tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMP_CODE]);
265 tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMP_ID]);
266
267 if (tuple->dst.u.icmp.type >= sizeof(invmap) ||
268 !invmap[tuple->dst.u.icmp.type])
269 return -EINVAL;
270
271 return 0;
272 }
273
icmp_nlattr_tuple_size(void)274 static int icmp_nlattr_tuple_size(void)
275 {
276 return nla_policy_len(icmp_nla_policy, CTA_PROTO_MAX + 1);
277 }
278 #endif
279
280 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
281
282 #include <linux/netfilter/nfnetlink.h>
283 #include <linux/netfilter/nfnetlink_cttimeout.h>
284
icmp_timeout_nlattr_to_obj(struct nlattr * tb[],struct net * net,void * data)285 static int icmp_timeout_nlattr_to_obj(struct nlattr *tb[],
286 struct net *net, void *data)
287 {
288 unsigned int *timeout = data;
289 struct nf_icmp_net *in = icmp_pernet(net);
290
291 if (tb[CTA_TIMEOUT_ICMP_TIMEOUT]) {
292 *timeout =
293 ntohl(nla_get_be32(tb[CTA_TIMEOUT_ICMP_TIMEOUT])) * HZ;
294 } else {
295 /* Set default ICMP timeout. */
296 *timeout = in->timeout;
297 }
298 return 0;
299 }
300
301 static int
icmp_timeout_obj_to_nlattr(struct sk_buff * skb,const void * data)302 icmp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
303 {
304 const unsigned int *timeout = data;
305
306 if (nla_put_be32(skb, CTA_TIMEOUT_ICMP_TIMEOUT, htonl(*timeout / HZ)))
307 goto nla_put_failure;
308 return 0;
309
310 nla_put_failure:
311 return -ENOSPC;
312 }
313
314 static const struct nla_policy
315 icmp_timeout_nla_policy[CTA_TIMEOUT_ICMP_MAX+1] = {
316 [CTA_TIMEOUT_ICMP_TIMEOUT] = { .type = NLA_U32 },
317 };
318 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
319
320 #ifdef CONFIG_SYSCTL
321 static struct ctl_table icmp_sysctl_table[] = {
322 {
323 .procname = "nf_conntrack_icmp_timeout",
324 .maxlen = sizeof(unsigned int),
325 .mode = 0644,
326 .proc_handler = proc_dointvec_jiffies,
327 },
328 { }
329 };
330 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
331 static struct ctl_table icmp_compat_sysctl_table[] = {
332 {
333 .procname = "ip_conntrack_icmp_timeout",
334 .maxlen = sizeof(unsigned int),
335 .mode = 0644,
336 .proc_handler = proc_dointvec_jiffies,
337 },
338 { }
339 };
340 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
341 #endif /* CONFIG_SYSCTL */
342
icmp_kmemdup_sysctl_table(struct nf_proto_net * pn,struct nf_icmp_net * in)343 static int icmp_kmemdup_sysctl_table(struct nf_proto_net *pn,
344 struct nf_icmp_net *in)
345 {
346 #ifdef CONFIG_SYSCTL
347 pn->ctl_table = kmemdup(icmp_sysctl_table,
348 sizeof(icmp_sysctl_table),
349 GFP_KERNEL);
350 if (!pn->ctl_table)
351 return -ENOMEM;
352
353 pn->ctl_table[0].data = &in->timeout;
354 #endif
355 return 0;
356 }
357
icmp_kmemdup_compat_sysctl_table(struct nf_proto_net * pn,struct nf_icmp_net * in)358 static int icmp_kmemdup_compat_sysctl_table(struct nf_proto_net *pn,
359 struct nf_icmp_net *in)
360 {
361 #ifdef CONFIG_SYSCTL
362 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
363 pn->ctl_compat_table = kmemdup(icmp_compat_sysctl_table,
364 sizeof(icmp_compat_sysctl_table),
365 GFP_KERNEL);
366 if (!pn->ctl_compat_table)
367 return -ENOMEM;
368
369 pn->ctl_compat_table[0].data = &in->timeout;
370 #endif
371 #endif
372 return 0;
373 }
374
icmp_init_net(struct net * net,u_int16_t proto)375 static int icmp_init_net(struct net *net, u_int16_t proto)
376 {
377 int ret;
378 struct nf_icmp_net *in = icmp_pernet(net);
379 struct nf_proto_net *pn = &in->pn;
380
381 in->timeout = nf_ct_icmp_timeout;
382
383 ret = icmp_kmemdup_compat_sysctl_table(pn, in);
384 if (ret < 0)
385 return ret;
386
387 ret = icmp_kmemdup_sysctl_table(pn, in);
388 if (ret < 0)
389 nf_ct_kfree_compat_sysctl_table(pn);
390
391 return ret;
392 }
393
icmp_get_net_proto(struct net * net)394 static struct nf_proto_net *icmp_get_net_proto(struct net *net)
395 {
396 return &net->ct.nf_ct_proto.icmp.pn;
397 }
398
399 struct nf_conntrack_l4proto nf_conntrack_l4proto_icmp __read_mostly =
400 {
401 .l3proto = PF_INET,
402 .l4proto = IPPROTO_ICMP,
403 .name = "icmp",
404 .pkt_to_tuple = icmp_pkt_to_tuple,
405 .invert_tuple = icmp_invert_tuple,
406 .print_tuple = icmp_print_tuple,
407 .packet = icmp_packet,
408 .get_timeouts = icmp_get_timeouts,
409 .new = icmp_new,
410 .error = icmp_error,
411 .destroy = NULL,
412 .me = NULL,
413 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
414 .tuple_to_nlattr = icmp_tuple_to_nlattr,
415 .nlattr_tuple_size = icmp_nlattr_tuple_size,
416 .nlattr_to_tuple = icmp_nlattr_to_tuple,
417 .nla_policy = icmp_nla_policy,
418 #endif
419 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
420 .ctnl_timeout = {
421 .nlattr_to_obj = icmp_timeout_nlattr_to_obj,
422 .obj_to_nlattr = icmp_timeout_obj_to_nlattr,
423 .nlattr_max = CTA_TIMEOUT_ICMP_MAX,
424 .obj_size = sizeof(unsigned int),
425 .nla_policy = icmp_timeout_nla_policy,
426 },
427 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
428 .init_net = icmp_init_net,
429 .get_net_proto = icmp_get_net_proto,
430 };
431