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 nf_conntrack_tuple * tuple)32 static bool icmp_pkt_to_tuple(const struct sk_buff *skb, unsigned int dataoff,
33 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 u16 zone = tmpl ? nf_ct_zone(tmpl) : NF_CT_DEFAULT_ZONE;
138
139 NF_CT_ASSERT(skb->nfct == NULL);
140
141 /* Are they talking about one of our connections? */
142 if (!nf_ct_get_tuplepr(skb,
143 skb_network_offset(skb) + ip_hdrlen(skb)
144 + sizeof(struct icmphdr),
145 PF_INET, &origtuple)) {
146 pr_debug("icmp_error_message: failed to get tuple\n");
147 return -NF_ACCEPT;
148 }
149
150 /* rcu_read_lock()ed by nf_hook_slow */
151 innerproto = __nf_ct_l4proto_find(PF_INET, origtuple.dst.protonum);
152
153 /* Ordinarily, we'd expect the inverted tupleproto, but it's
154 been preserved inside the ICMP. */
155 if (!nf_ct_invert_tuple(&innertuple, &origtuple,
156 &nf_conntrack_l3proto_ipv4, innerproto)) {
157 pr_debug("icmp_error_message: no match\n");
158 return -NF_ACCEPT;
159 }
160
161 *ctinfo = IP_CT_RELATED;
162
163 h = nf_conntrack_find_get(net, zone, &innertuple);
164 if (!h) {
165 pr_debug("icmp_error_message: no match\n");
166 return -NF_ACCEPT;
167 }
168
169 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
170 *ctinfo += IP_CT_IS_REPLY;
171
172 /* Update skb to refer to this connection */
173 skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general;
174 skb->nfctinfo = *ctinfo;
175 return NF_ACCEPT;
176 }
177
178 /* Small and modified version of icmp_rcv */
179 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)180 icmp_error(struct net *net, struct nf_conn *tmpl,
181 struct sk_buff *skb, unsigned int dataoff,
182 enum ip_conntrack_info *ctinfo, u_int8_t pf, unsigned int hooknum)
183 {
184 const struct icmphdr *icmph;
185 struct icmphdr _ih;
186
187 /* Not enough header? */
188 icmph = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_ih), &_ih);
189 if (icmph == NULL) {
190 if (LOG_INVALID(net, IPPROTO_ICMP))
191 nf_log_packet(net, PF_INET, 0, skb, NULL, NULL,
192 NULL, "nf_ct_icmp: short packet ");
193 return -NF_ACCEPT;
194 }
195
196 /* See ip_conntrack_proto_tcp.c */
197 if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
198 nf_ip_checksum(skb, hooknum, dataoff, 0)) {
199 if (LOG_INVALID(net, IPPROTO_ICMP))
200 nf_log_packet(net, PF_INET, 0, skb, NULL, NULL, NULL,
201 "nf_ct_icmp: bad HW ICMP checksum ");
202 return -NF_ACCEPT;
203 }
204
205 /*
206 * 18 is the highest 'known' ICMP type. Anything else is a mystery
207 *
208 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
209 * discarded.
210 */
211 if (icmph->type > NR_ICMP_TYPES) {
212 if (LOG_INVALID(net, IPPROTO_ICMP))
213 nf_log_packet(net, PF_INET, 0, skb, NULL, NULL, NULL,
214 "nf_ct_icmp: invalid ICMP type ");
215 return -NF_ACCEPT;
216 }
217
218 /* Need to track icmp error message? */
219 if (icmph->type != ICMP_DEST_UNREACH &&
220 icmph->type != ICMP_SOURCE_QUENCH &&
221 icmph->type != ICMP_TIME_EXCEEDED &&
222 icmph->type != ICMP_PARAMETERPROB &&
223 icmph->type != ICMP_REDIRECT)
224 return NF_ACCEPT;
225
226 return icmp_error_message(net, tmpl, skb, ctinfo, hooknum);
227 }
228
229 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
230
231 #include <linux/netfilter/nfnetlink.h>
232 #include <linux/netfilter/nfnetlink_conntrack.h>
233
icmp_tuple_to_nlattr(struct sk_buff * skb,const struct nf_conntrack_tuple * t)234 static int icmp_tuple_to_nlattr(struct sk_buff *skb,
235 const struct nf_conntrack_tuple *t)
236 {
237 if (nla_put_be16(skb, CTA_PROTO_ICMP_ID, t->src.u.icmp.id) ||
238 nla_put_u8(skb, CTA_PROTO_ICMP_TYPE, t->dst.u.icmp.type) ||
239 nla_put_u8(skb, CTA_PROTO_ICMP_CODE, t->dst.u.icmp.code))
240 goto nla_put_failure;
241 return 0;
242
243 nla_put_failure:
244 return -1;
245 }
246
247 static const struct nla_policy icmp_nla_policy[CTA_PROTO_MAX+1] = {
248 [CTA_PROTO_ICMP_TYPE] = { .type = NLA_U8 },
249 [CTA_PROTO_ICMP_CODE] = { .type = NLA_U8 },
250 [CTA_PROTO_ICMP_ID] = { .type = NLA_U16 },
251 };
252
icmp_nlattr_to_tuple(struct nlattr * tb[],struct nf_conntrack_tuple * tuple)253 static int icmp_nlattr_to_tuple(struct nlattr *tb[],
254 struct nf_conntrack_tuple *tuple)
255 {
256 if (!tb[CTA_PROTO_ICMP_TYPE] ||
257 !tb[CTA_PROTO_ICMP_CODE] ||
258 !tb[CTA_PROTO_ICMP_ID])
259 return -EINVAL;
260
261 tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMP_TYPE]);
262 tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMP_CODE]);
263 tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMP_ID]);
264
265 if (tuple->dst.u.icmp.type >= sizeof(invmap) ||
266 !invmap[tuple->dst.u.icmp.type])
267 return -EINVAL;
268
269 return 0;
270 }
271
icmp_nlattr_tuple_size(void)272 static int icmp_nlattr_tuple_size(void)
273 {
274 return nla_policy_len(icmp_nla_policy, CTA_PROTO_MAX + 1);
275 }
276 #endif
277
278 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
279
280 #include <linux/netfilter/nfnetlink.h>
281 #include <linux/netfilter/nfnetlink_cttimeout.h>
282
icmp_timeout_nlattr_to_obj(struct nlattr * tb[],struct net * net,void * data)283 static int icmp_timeout_nlattr_to_obj(struct nlattr *tb[],
284 struct net *net, void *data)
285 {
286 unsigned int *timeout = data;
287 struct nf_icmp_net *in = icmp_pernet(net);
288
289 if (tb[CTA_TIMEOUT_ICMP_TIMEOUT]) {
290 *timeout =
291 ntohl(nla_get_be32(tb[CTA_TIMEOUT_ICMP_TIMEOUT])) * HZ;
292 } else {
293 /* Set default ICMP timeout. */
294 *timeout = in->timeout;
295 }
296 return 0;
297 }
298
299 static int
icmp_timeout_obj_to_nlattr(struct sk_buff * skb,const void * data)300 icmp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
301 {
302 const unsigned int *timeout = data;
303
304 if (nla_put_be32(skb, CTA_TIMEOUT_ICMP_TIMEOUT, htonl(*timeout / HZ)))
305 goto nla_put_failure;
306 return 0;
307
308 nla_put_failure:
309 return -ENOSPC;
310 }
311
312 static const struct nla_policy
313 icmp_timeout_nla_policy[CTA_TIMEOUT_ICMP_MAX+1] = {
314 [CTA_TIMEOUT_ICMP_TIMEOUT] = { .type = NLA_U32 },
315 };
316 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
317
318 #ifdef CONFIG_SYSCTL
319 static struct ctl_table icmp_sysctl_table[] = {
320 {
321 .procname = "nf_conntrack_icmp_timeout",
322 .maxlen = sizeof(unsigned int),
323 .mode = 0644,
324 .proc_handler = proc_dointvec_jiffies,
325 },
326 { }
327 };
328 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
329 static struct ctl_table icmp_compat_sysctl_table[] = {
330 {
331 .procname = "ip_conntrack_icmp_timeout",
332 .maxlen = sizeof(unsigned int),
333 .mode = 0644,
334 .proc_handler = proc_dointvec_jiffies,
335 },
336 { }
337 };
338 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
339 #endif /* CONFIG_SYSCTL */
340
icmp_kmemdup_sysctl_table(struct nf_proto_net * pn,struct nf_icmp_net * in)341 static int icmp_kmemdup_sysctl_table(struct nf_proto_net *pn,
342 struct nf_icmp_net *in)
343 {
344 #ifdef CONFIG_SYSCTL
345 pn->ctl_table = kmemdup(icmp_sysctl_table,
346 sizeof(icmp_sysctl_table),
347 GFP_KERNEL);
348 if (!pn->ctl_table)
349 return -ENOMEM;
350
351 pn->ctl_table[0].data = &in->timeout;
352 #endif
353 return 0;
354 }
355
icmp_kmemdup_compat_sysctl_table(struct nf_proto_net * pn,struct nf_icmp_net * in)356 static int icmp_kmemdup_compat_sysctl_table(struct nf_proto_net *pn,
357 struct nf_icmp_net *in)
358 {
359 #ifdef CONFIG_SYSCTL
360 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
361 pn->ctl_compat_table = kmemdup(icmp_compat_sysctl_table,
362 sizeof(icmp_compat_sysctl_table),
363 GFP_KERNEL);
364 if (!pn->ctl_compat_table)
365 return -ENOMEM;
366
367 pn->ctl_compat_table[0].data = &in->timeout;
368 #endif
369 #endif
370 return 0;
371 }
372
icmp_init_net(struct net * net,u_int16_t proto)373 static int icmp_init_net(struct net *net, u_int16_t proto)
374 {
375 int ret;
376 struct nf_icmp_net *in = icmp_pernet(net);
377 struct nf_proto_net *pn = &in->pn;
378
379 in->timeout = nf_ct_icmp_timeout;
380
381 ret = icmp_kmemdup_compat_sysctl_table(pn, in);
382 if (ret < 0)
383 return ret;
384
385 ret = icmp_kmemdup_sysctl_table(pn, in);
386 if (ret < 0)
387 nf_ct_kfree_compat_sysctl_table(pn);
388
389 return ret;
390 }
391
icmp_get_net_proto(struct net * net)392 static struct nf_proto_net *icmp_get_net_proto(struct net *net)
393 {
394 return &net->ct.nf_ct_proto.icmp.pn;
395 }
396
397 struct nf_conntrack_l4proto nf_conntrack_l4proto_icmp __read_mostly =
398 {
399 .l3proto = PF_INET,
400 .l4proto = IPPROTO_ICMP,
401 .name = "icmp",
402 .pkt_to_tuple = icmp_pkt_to_tuple,
403 .invert_tuple = icmp_invert_tuple,
404 .print_tuple = icmp_print_tuple,
405 .packet = icmp_packet,
406 .get_timeouts = icmp_get_timeouts,
407 .new = icmp_new,
408 .error = icmp_error,
409 .destroy = NULL,
410 .me = NULL,
411 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
412 .tuple_to_nlattr = icmp_tuple_to_nlattr,
413 .nlattr_tuple_size = icmp_nlattr_tuple_size,
414 .nlattr_to_tuple = icmp_nlattr_to_tuple,
415 .nla_policy = icmp_nla_policy,
416 #endif
417 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
418 .ctnl_timeout = {
419 .nlattr_to_obj = icmp_timeout_nlattr_to_obj,
420 .obj_to_nlattr = icmp_timeout_obj_to_nlattr,
421 .nlattr_max = CTA_TIMEOUT_ICMP_MAX,
422 .obj_size = sizeof(unsigned int),
423 .nla_policy = icmp_timeout_nla_policy,
424 },
425 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
426 .init_net = icmp_init_net,
427 .get_net_proto = icmp_get_net_proto,
428 };
429