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 */