1 // SPDX-License-Identifier: GPL-2.0-only
2 /* (C) 1999-2001 Paul `Rusty' Russell
3 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
4 * (C) 2006-2010 Patrick McHardy <kaber@trash.net>
7 #include <linux/types.h>
8 #include <linux/timer.h>
9 #include <linux/netfilter.h>
11 #include <linux/icmp.h>
12 #include <linux/seq_file.h>
14 #include <net/checksum.h>
15 #include <linux/netfilter_ipv4.h>
16 #include <net/netfilter/nf_conntrack_tuple.h>
17 #include <net/netfilter/nf_conntrack_l4proto.h>
18 #include <net/netfilter/nf_conntrack_core.h>
19 #include <net/netfilter/nf_conntrack_timeout.h>
20 #include <net/netfilter/nf_conntrack_zones.h>
21 #include <net/netfilter/nf_log.h>
23 #include "nf_internals.h"
25 static const unsigned int nf_ct_icmp_timeout = 30*HZ;
27 bool icmp_pkt_to_tuple(const struct sk_buff *skb, unsigned int dataoff,
28 struct net *net, struct nf_conntrack_tuple *tuple)
30 const struct icmphdr *hp;
33 hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
37 tuple->dst.u.icmp.type = hp->type;
38 tuple->src.u.icmp.id = hp->un.echo.id;
39 tuple->dst.u.icmp.code = hp->code;
44 /* Add 1; spaces filled with 0. */
45 static const u_int8_t invmap[] = {
46 [ICMP_ECHO] = ICMP_ECHOREPLY + 1,
47 [ICMP_ECHOREPLY] = ICMP_ECHO + 1,
48 [ICMP_TIMESTAMP] = ICMP_TIMESTAMPREPLY + 1,
49 [ICMP_TIMESTAMPREPLY] = ICMP_TIMESTAMP + 1,
50 [ICMP_INFO_REQUEST] = ICMP_INFO_REPLY + 1,
51 [ICMP_INFO_REPLY] = ICMP_INFO_REQUEST + 1,
52 [ICMP_ADDRESS] = ICMP_ADDRESSREPLY + 1,
53 [ICMP_ADDRESSREPLY] = ICMP_ADDRESS + 1
56 bool nf_conntrack_invert_icmp_tuple(struct nf_conntrack_tuple *tuple,
57 const struct nf_conntrack_tuple *orig)
59 if (orig->dst.u.icmp.type >= sizeof(invmap) ||
60 !invmap[orig->dst.u.icmp.type])
63 tuple->src.u.icmp.id = orig->src.u.icmp.id;
64 tuple->dst.u.icmp.type = invmap[orig->dst.u.icmp.type] - 1;
65 tuple->dst.u.icmp.code = orig->dst.u.icmp.code;
69 /* Returns verdict for packet, or -1 for invalid. */
70 int nf_conntrack_icmp_packet(struct nf_conn *ct,
72 enum ip_conntrack_info ctinfo,
73 const struct nf_hook_state *state)
75 /* Do not immediately delete the connection after the first
76 successful reply to avoid excessive conntrackd traffic
77 and also to handle correctly ICMP echo reply duplicates. */
78 unsigned int *timeout = nf_ct_timeout_lookup(ct);
79 static const u_int8_t valid_new[] = {
82 [ICMP_INFO_REQUEST] = 1,
86 if (state->pf != NFPROTO_IPV4)
89 if (ct->tuplehash[0].tuple.dst.u.icmp.type >= sizeof(valid_new) ||
90 !valid_new[ct->tuplehash[0].tuple.dst.u.icmp.type]) {
91 /* Can't create a new ICMP `conn' with this. */
92 pr_debug("icmp: can't create new conn with type %u\n",
93 ct->tuplehash[0].tuple.dst.u.icmp.type);
94 nf_ct_dump_tuple_ip(&ct->tuplehash[0].tuple);
99 timeout = &nf_icmp_pernet(nf_ct_net(ct))->timeout;
101 nf_ct_refresh_acct(ct, ctinfo, skb, *timeout);
105 /* Check inner header is related to any of the existing connections */
106 int nf_conntrack_inet_error(struct nf_conn *tmpl, struct sk_buff *skb,
107 unsigned int dataoff,
108 const struct nf_hook_state *state,
109 u8 l4proto, union nf_inet_addr *outer_daddr)
111 struct nf_conntrack_tuple innertuple, origtuple;
112 const struct nf_conntrack_tuple_hash *h;
113 const struct nf_conntrack_zone *zone;
114 enum ip_conntrack_info ctinfo;
115 struct nf_conntrack_zone tmp;
116 union nf_inet_addr *ct_daddr;
117 enum ip_conntrack_dir dir;
120 WARN_ON(skb_nfct(skb));
121 zone = nf_ct_zone_tmpl(tmpl, skb, &tmp);
123 /* Are they talking about one of our connections? */
124 if (!nf_ct_get_tuplepr(skb, dataoff,
125 state->pf, state->net, &origtuple))
128 /* Ordinarily, we'd expect the inverted tupleproto, but it's
129 been preserved inside the ICMP. */
130 if (!nf_ct_invert_tuple(&innertuple, &origtuple))
133 h = nf_conntrack_find_get(state->net, zone, &innertuple);
137 /* Consider: A -> T (=This machine) -> B
138 * Conntrack entry will look like this:
140 * Reply: B->T (SNAT case) OR A
142 * When this function runs, we got packet that looks like this:
143 * iphdr|icmphdr|inner_iphdr|l4header (tcp, udp, ..).
145 * Above nf_conntrack_find_get() makes lookup based on inner_hdr,
146 * so we should expect that destination of the found connection
147 * matches outer header destination address.
149 * In above example, we can consider these two cases:
150 * 1. Error coming in reply direction from B or M (middle box) to
151 * T (SNAT case) or A.
152 * Inner saddr will be B, dst will be T or A.
153 * The found conntrack will be reply tuple (B->T/A).
154 * 2. Error coming in original direction from A or M to B.
155 * Inner saddr will be A, inner daddr will be B.
156 * The found conntrack will be original tuple (A->B).
158 * In both cases, conntrack[dir].dst == inner.dst.
160 * A bogus packet could look like this:
162 * Outer: B->X (other machine reachable by T).
164 * In this case, lookup yields connection A->B and will
165 * set packet from B->X as *RELATED*, even though no connection
166 * from X was ever seen.
168 ct = nf_ct_tuplehash_to_ctrack(h);
169 dir = NF_CT_DIRECTION(h);
170 ct_daddr = &ct->tuplehash[dir].tuple.dst.u3;
171 if (!nf_inet_addr_cmp(outer_daddr, ct_daddr)) {
172 if (state->pf == AF_INET) {
173 nf_l4proto_log_invalid(skb, state,
175 "outer daddr %pI4 != inner %pI4",
176 &outer_daddr->ip, &ct_daddr->ip);
177 } else if (state->pf == AF_INET6) {
178 nf_l4proto_log_invalid(skb, state,
180 "outer daddr %pI6 != inner %pI6",
181 &outer_daddr->ip6, &ct_daddr->ip6);
187 ctinfo = IP_CT_RELATED;
188 if (dir == IP_CT_DIR_REPLY)
189 ctinfo += IP_CT_IS_REPLY;
191 /* Update skb to refer to this connection */
192 nf_ct_set(skb, ct, ctinfo);
196 static void icmp_error_log(const struct sk_buff *skb,
197 const struct nf_hook_state *state,
200 nf_l4proto_log_invalid(skb, state, IPPROTO_ICMP, "%s", msg);
203 /* Small and modified version of icmp_rcv */
204 int nf_conntrack_icmpv4_error(struct nf_conn *tmpl,
205 struct sk_buff *skb, unsigned int dataoff,
206 const struct nf_hook_state *state)
208 union nf_inet_addr outer_daddr;
209 const struct icmphdr *icmph;
212 /* Not enough header? */
213 icmph = skb_header_pointer(skb, dataoff, sizeof(_ih), &_ih);
215 icmp_error_log(skb, state, "short packet");
219 /* See nf_conntrack_proto_tcp.c */
220 if (state->net->ct.sysctl_checksum &&
221 state->hook == NF_INET_PRE_ROUTING &&
222 nf_ip_checksum(skb, state->hook, dataoff, IPPROTO_ICMP)) {
223 icmp_error_log(skb, state, "bad hw icmp checksum");
228 * 18 is the highest 'known' ICMP type. Anything else is a mystery
230 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
233 if (icmph->type > NR_ICMP_TYPES) {
234 icmp_error_log(skb, state, "invalid icmp type");
238 /* Need to track icmp error message? */
239 if (!icmp_is_err(icmph->type))
242 memset(&outer_daddr, 0, sizeof(outer_daddr));
243 outer_daddr.ip = ip_hdr(skb)->daddr;
245 dataoff += sizeof(*icmph);
246 return nf_conntrack_inet_error(tmpl, skb, dataoff, state,
247 IPPROTO_ICMP, &outer_daddr);
250 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
252 #include <linux/netfilter/nfnetlink.h>
253 #include <linux/netfilter/nfnetlink_conntrack.h>
255 static int icmp_tuple_to_nlattr(struct sk_buff *skb,
256 const struct nf_conntrack_tuple *t)
258 if (nla_put_be16(skb, CTA_PROTO_ICMP_ID, t->src.u.icmp.id) ||
259 nla_put_u8(skb, CTA_PROTO_ICMP_TYPE, t->dst.u.icmp.type) ||
260 nla_put_u8(skb, CTA_PROTO_ICMP_CODE, t->dst.u.icmp.code))
261 goto nla_put_failure;
268 static const struct nla_policy icmp_nla_policy[CTA_PROTO_MAX+1] = {
269 [CTA_PROTO_ICMP_TYPE] = { .type = NLA_U8 },
270 [CTA_PROTO_ICMP_CODE] = { .type = NLA_U8 },
271 [CTA_PROTO_ICMP_ID] = { .type = NLA_U16 },
274 static int icmp_nlattr_to_tuple(struct nlattr *tb[],
275 struct nf_conntrack_tuple *tuple,
278 if (flags & CTA_FILTER_FLAG(CTA_PROTO_ICMP_TYPE)) {
279 if (!tb[CTA_PROTO_ICMP_TYPE])
282 tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMP_TYPE]);
283 if (tuple->dst.u.icmp.type >= sizeof(invmap) ||
284 !invmap[tuple->dst.u.icmp.type])
288 if (flags & CTA_FILTER_FLAG(CTA_PROTO_ICMP_CODE)) {
289 if (!tb[CTA_PROTO_ICMP_CODE])
292 tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMP_CODE]);
295 if (flags & CTA_FILTER_FLAG(CTA_PROTO_ICMP_ID)) {
296 if (!tb[CTA_PROTO_ICMP_ID])
299 tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMP_ID]);
305 static unsigned int icmp_nlattr_tuple_size(void)
307 static unsigned int size __read_mostly;
310 size = nla_policy_len(icmp_nla_policy, CTA_PROTO_MAX + 1);
316 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
318 #include <linux/netfilter/nfnetlink.h>
319 #include <linux/netfilter/nfnetlink_cttimeout.h>
321 static int icmp_timeout_nlattr_to_obj(struct nlattr *tb[],
322 struct net *net, void *data)
324 unsigned int *timeout = data;
325 struct nf_icmp_net *in = nf_icmp_pernet(net);
327 if (tb[CTA_TIMEOUT_ICMP_TIMEOUT]) {
329 timeout = &in->timeout;
331 ntohl(nla_get_be32(tb[CTA_TIMEOUT_ICMP_TIMEOUT])) * HZ;
332 } else if (timeout) {
333 /* Set default ICMP timeout. */
334 *timeout = in->timeout;
340 icmp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
342 const unsigned int *timeout = data;
344 if (nla_put_be32(skb, CTA_TIMEOUT_ICMP_TIMEOUT, htonl(*timeout / HZ)))
345 goto nla_put_failure;
352 static const struct nla_policy
353 icmp_timeout_nla_policy[CTA_TIMEOUT_ICMP_MAX+1] = {
354 [CTA_TIMEOUT_ICMP_TIMEOUT] = { .type = NLA_U32 },
356 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
358 void nf_conntrack_icmp_init_net(struct net *net)
360 struct nf_icmp_net *in = nf_icmp_pernet(net);
362 in->timeout = nf_ct_icmp_timeout;
365 const struct nf_conntrack_l4proto nf_conntrack_l4proto_icmp =
367 .l4proto = IPPROTO_ICMP,
368 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
369 .tuple_to_nlattr = icmp_tuple_to_nlattr,
370 .nlattr_tuple_size = icmp_nlattr_tuple_size,
371 .nlattr_to_tuple = icmp_nlattr_to_tuple,
372 .nla_policy = icmp_nla_policy,
374 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
376 .nlattr_to_obj = icmp_timeout_nlattr_to_obj,
377 .obj_to_nlattr = icmp_timeout_obj_to_nlattr,
378 .nlattr_max = CTA_TIMEOUT_ICMP_MAX,
379 .obj_size = sizeof(unsigned int),
380 .nla_policy = icmp_timeout_nla_policy,
382 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */