2 * ip_conntrack_proto_gre.c - Version 3.0
4 * Connection tracking protocol helper module for GRE.
6 * GRE is a generic encapsulation protocol, which is generally not very
7 * suited for NAT, as it has no protocol-specific part as port numbers.
9 * It has an optional key field, which may help us distinguishing two
10 * connections between the same two hosts.
12 * GRE is defined in RFC 1701 and RFC 1702, as well as RFC 2784
14 * PPTP is built on top of a modified version of GRE, and has a mandatory
15 * field called "CallID", which serves us for the same purpose as the key
18 * Documentation about PPTP can be found in RFC 2637
20 * (C) 2000-2005 by Harald Welte <laforge@gnumonks.org>
22 * Development of this code funded by Astaro AG (http://www.astaro.com/)
24 * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
27 #include <linux/module.h>
28 #include <linux/types.h>
29 #include <linux/timer.h>
30 #include <linux/list.h>
31 #include <linux/seq_file.h>
33 #include <linux/netdevice.h>
34 #include <linux/skbuff.h>
35 #include <linux/slab.h>
37 #include <net/net_namespace.h>
38 #include <net/netns/generic.h>
39 #include <net/netfilter/nf_conntrack_l4proto.h>
40 #include <net/netfilter/nf_conntrack_helper.h>
41 #include <net/netfilter/nf_conntrack_core.h>
42 #include <net/netfilter/nf_conntrack_timeout.h>
43 #include <linux/netfilter/nf_conntrack_proto_gre.h>
44 #include <linux/netfilter/nf_conntrack_pptp.h>
46 static const unsigned int gre_timeouts
[GRE_CT_MAX
] = {
47 [GRE_CT_UNREPLIED
] = 30*HZ
,
48 [GRE_CT_REPLIED
] = 180*HZ
,
51 static unsigned int proto_gre_net_id __read_mostly
;
53 static inline struct netns_proto_gre
*gre_pernet(struct net
*net
)
55 return net_generic(net
, proto_gre_net_id
);
58 static void nf_ct_gre_keymap_flush(struct net
*net
)
60 struct netns_proto_gre
*net_gre
= gre_pernet(net
);
61 struct nf_ct_gre_keymap
*km
, *tmp
;
63 write_lock_bh(&net_gre
->keymap_lock
);
64 list_for_each_entry_safe(km
, tmp
, &net_gre
->keymap_list
, list
) {
68 write_unlock_bh(&net_gre
->keymap_lock
);
71 static inline int gre_key_cmpfn(const struct nf_ct_gre_keymap
*km
,
72 const struct nf_conntrack_tuple
*t
)
74 return km
->tuple
.src
.l3num
== t
->src
.l3num
&&
75 !memcmp(&km
->tuple
.src
.u3
, &t
->src
.u3
, sizeof(t
->src
.u3
)) &&
76 !memcmp(&km
->tuple
.dst
.u3
, &t
->dst
.u3
, sizeof(t
->dst
.u3
)) &&
77 km
->tuple
.dst
.protonum
== t
->dst
.protonum
&&
78 km
->tuple
.dst
.u
.all
== t
->dst
.u
.all
;
81 /* look up the source key for a given tuple */
82 static __be16
gre_keymap_lookup(struct net
*net
, struct nf_conntrack_tuple
*t
)
84 struct netns_proto_gre
*net_gre
= gre_pernet(net
);
85 struct nf_ct_gre_keymap
*km
;
88 read_lock_bh(&net_gre
->keymap_lock
);
89 list_for_each_entry(km
, &net_gre
->keymap_list
, list
) {
90 if (gre_key_cmpfn(km
, t
)) {
91 key
= km
->tuple
.src
.u
.gre
.key
;
95 read_unlock_bh(&net_gre
->keymap_lock
);
97 pr_debug("lookup src key 0x%x for ", key
);
103 /* add a single keymap entry, associate with specified master ct */
104 int nf_ct_gre_keymap_add(struct nf_conn
*ct
, enum ip_conntrack_dir dir
,
105 struct nf_conntrack_tuple
*t
)
107 struct net
*net
= nf_ct_net(ct
);
108 struct netns_proto_gre
*net_gre
= gre_pernet(net
);
109 struct nf_ct_pptp_master
*ct_pptp_info
= nfct_help_data(ct
);
110 struct nf_ct_gre_keymap
**kmp
, *km
;
112 kmp
= &ct_pptp_info
->keymap
[dir
];
114 /* check whether it's a retransmission */
115 read_lock_bh(&net_gre
->keymap_lock
);
116 list_for_each_entry(km
, &net_gre
->keymap_list
, list
) {
117 if (gre_key_cmpfn(km
, t
) && km
== *kmp
) {
118 read_unlock_bh(&net_gre
->keymap_lock
);
122 read_unlock_bh(&net_gre
->keymap_lock
);
123 pr_debug("trying to override keymap_%s for ct %p\n",
124 dir
== IP_CT_DIR_REPLY
? "reply" : "orig", ct
);
128 km
= kmalloc(sizeof(*km
), GFP_ATOMIC
);
131 memcpy(&km
->tuple
, t
, sizeof(*t
));
134 pr_debug("adding new entry %p: ", km
);
135 nf_ct_dump_tuple(&km
->tuple
);
137 write_lock_bh(&net_gre
->keymap_lock
);
138 list_add_tail(&km
->list
, &net_gre
->keymap_list
);
139 write_unlock_bh(&net_gre
->keymap_lock
);
143 EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_add
);
145 /* destroy the keymap entries associated with specified master ct */
146 void nf_ct_gre_keymap_destroy(struct nf_conn
*ct
)
148 struct net
*net
= nf_ct_net(ct
);
149 struct netns_proto_gre
*net_gre
= gre_pernet(net
);
150 struct nf_ct_pptp_master
*ct_pptp_info
= nfct_help_data(ct
);
151 enum ip_conntrack_dir dir
;
153 pr_debug("entering for ct %p\n", ct
);
155 write_lock_bh(&net_gre
->keymap_lock
);
156 for (dir
= IP_CT_DIR_ORIGINAL
; dir
< IP_CT_DIR_MAX
; dir
++) {
157 if (ct_pptp_info
->keymap
[dir
]) {
158 pr_debug("removing %p from list\n",
159 ct_pptp_info
->keymap
[dir
]);
160 list_del(&ct_pptp_info
->keymap
[dir
]->list
);
161 kfree(ct_pptp_info
->keymap
[dir
]);
162 ct_pptp_info
->keymap
[dir
] = NULL
;
165 write_unlock_bh(&net_gre
->keymap_lock
);
167 EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_destroy
);
169 /* PUBLIC CONNTRACK PROTO HELPER FUNCTIONS */
171 /* gre hdr info to tuple */
172 static bool gre_pkt_to_tuple(const struct sk_buff
*skb
, unsigned int dataoff
,
173 struct net
*net
, struct nf_conntrack_tuple
*tuple
)
175 const struct pptp_gre_header
*pgrehdr
;
176 struct pptp_gre_header _pgrehdr
;
178 const struct gre_base_hdr
*grehdr
;
179 struct gre_base_hdr _grehdr
;
181 /* first only delinearize old RFC1701 GRE header */
182 grehdr
= skb_header_pointer(skb
, dataoff
, sizeof(_grehdr
), &_grehdr
);
183 if (!grehdr
|| (grehdr
->flags
& GRE_VERSION
) != GRE_VERSION_1
) {
184 /* try to behave like "nf_conntrack_proto_generic" */
185 tuple
->src
.u
.all
= 0;
186 tuple
->dst
.u
.all
= 0;
190 /* PPTP header is variable length, only need up to the call_id field */
191 pgrehdr
= skb_header_pointer(skb
, dataoff
, 8, &_pgrehdr
);
195 if (grehdr
->protocol
!= GRE_PROTO_PPP
) {
196 pr_debug("Unsupported GRE proto(0x%x)\n", ntohs(grehdr
->protocol
));
200 tuple
->dst
.u
.gre
.key
= pgrehdr
->call_id
;
201 srckey
= gre_keymap_lookup(net
, tuple
);
202 tuple
->src
.u
.gre
.key
= srckey
;
207 #ifdef CONFIG_NF_CONNTRACK_PROCFS
208 /* print private data for conntrack */
209 static void gre_print_conntrack(struct seq_file
*s
, struct nf_conn
*ct
)
211 seq_printf(s
, "timeout=%u, stream_timeout=%u ",
212 (ct
->proto
.gre
.timeout
/ HZ
),
213 (ct
->proto
.gre
.stream_timeout
/ HZ
));
217 static unsigned int *gre_get_timeouts(struct net
*net
)
219 return gre_pernet(net
)->gre_timeouts
;
222 /* Returns verdict for packet, and may modify conntrack */
223 static int gre_packet(struct nf_conn
*ct
,
225 unsigned int dataoff
,
226 enum ip_conntrack_info ctinfo
,
227 const struct nf_hook_state
*state
)
229 if (state
->pf
!= NFPROTO_IPV4
)
232 if (!nf_ct_is_confirmed(ct
)) {
233 unsigned int *timeouts
= nf_ct_timeout_lookup(ct
);
236 timeouts
= gre_get_timeouts(nf_ct_net(ct
));
238 /* initialize to sane value. Ideally a conntrack helper
239 * (e.g. in case of pptp) is increasing them */
240 ct
->proto
.gre
.stream_timeout
= timeouts
[GRE_CT_REPLIED
];
241 ct
->proto
.gre
.timeout
= timeouts
[GRE_CT_UNREPLIED
];
244 /* If we've seen traffic both ways, this is a GRE connection.
246 if (ct
->status
& IPS_SEEN_REPLY
) {
247 nf_ct_refresh_acct(ct
, ctinfo
, skb
,
248 ct
->proto
.gre
.stream_timeout
);
249 /* Also, more likely to be important, and not a probe. */
250 if (!test_and_set_bit(IPS_ASSURED_BIT
, &ct
->status
))
251 nf_conntrack_event_cache(IPCT_ASSURED
, ct
);
253 nf_ct_refresh_acct(ct
, ctinfo
, skb
,
254 ct
->proto
.gre
.timeout
);
259 /* Called when a conntrack entry has already been removed from the hashes
260 * and is about to be deleted from memory */
261 static void gre_destroy(struct nf_conn
*ct
)
263 struct nf_conn
*master
= ct
->master
;
264 pr_debug(" entering\n");
267 pr_debug("no master !?!\n");
269 nf_ct_gre_keymap_destroy(master
);
272 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
274 #include <linux/netfilter/nfnetlink.h>
275 #include <linux/netfilter/nfnetlink_cttimeout.h>
277 static int gre_timeout_nlattr_to_obj(struct nlattr
*tb
[],
278 struct net
*net
, void *data
)
280 unsigned int *timeouts
= data
;
281 struct netns_proto_gre
*net_gre
= gre_pernet(net
);
284 timeouts
= gre_get_timeouts(net
);
285 /* set default timeouts for GRE. */
286 timeouts
[GRE_CT_UNREPLIED
] = net_gre
->gre_timeouts
[GRE_CT_UNREPLIED
];
287 timeouts
[GRE_CT_REPLIED
] = net_gre
->gre_timeouts
[GRE_CT_REPLIED
];
289 if (tb
[CTA_TIMEOUT_GRE_UNREPLIED
]) {
290 timeouts
[GRE_CT_UNREPLIED
] =
291 ntohl(nla_get_be32(tb
[CTA_TIMEOUT_GRE_UNREPLIED
])) * HZ
;
293 if (tb
[CTA_TIMEOUT_GRE_REPLIED
]) {
294 timeouts
[GRE_CT_REPLIED
] =
295 ntohl(nla_get_be32(tb
[CTA_TIMEOUT_GRE_REPLIED
])) * HZ
;
301 gre_timeout_obj_to_nlattr(struct sk_buff
*skb
, const void *data
)
303 const unsigned int *timeouts
= data
;
305 if (nla_put_be32(skb
, CTA_TIMEOUT_GRE_UNREPLIED
,
306 htonl(timeouts
[GRE_CT_UNREPLIED
] / HZ
)) ||
307 nla_put_be32(skb
, CTA_TIMEOUT_GRE_REPLIED
,
308 htonl(timeouts
[GRE_CT_REPLIED
] / HZ
)))
309 goto nla_put_failure
;
316 static const struct nla_policy
317 gre_timeout_nla_policy
[CTA_TIMEOUT_GRE_MAX
+1] = {
318 [CTA_TIMEOUT_GRE_UNREPLIED
] = { .type
= NLA_U32
},
319 [CTA_TIMEOUT_GRE_REPLIED
] = { .type
= NLA_U32
},
321 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
323 static int gre_init_net(struct net
*net
)
325 struct netns_proto_gre
*net_gre
= gre_pernet(net
);
328 rwlock_init(&net_gre
->keymap_lock
);
329 INIT_LIST_HEAD(&net_gre
->keymap_list
);
330 for (i
= 0; i
< GRE_CT_MAX
; i
++)
331 net_gre
->gre_timeouts
[i
] = gre_timeouts
[i
];
336 /* protocol helper struct */
337 static const struct nf_conntrack_l4proto nf_conntrack_l4proto_gre4
= {
338 .l4proto
= IPPROTO_GRE
,
339 .pkt_to_tuple
= gre_pkt_to_tuple
,
340 #ifdef CONFIG_NF_CONNTRACK_PROCFS
341 .print_conntrack
= gre_print_conntrack
,
343 .packet
= gre_packet
,
344 .destroy
= gre_destroy
,
346 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
347 .tuple_to_nlattr
= nf_ct_port_tuple_to_nlattr
,
348 .nlattr_tuple_size
= nf_ct_port_nlattr_tuple_size
,
349 .nlattr_to_tuple
= nf_ct_port_nlattr_to_tuple
,
350 .nla_policy
= nf_ct_port_nla_policy
,
352 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
354 .nlattr_to_obj
= gre_timeout_nlattr_to_obj
,
355 .obj_to_nlattr
= gre_timeout_obj_to_nlattr
,
356 .nlattr_max
= CTA_TIMEOUT_GRE_MAX
,
357 .obj_size
= sizeof(unsigned int) * GRE_CT_MAX
,
358 .nla_policy
= gre_timeout_nla_policy
,
360 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
361 .net_id
= &proto_gre_net_id
,
362 .init_net
= gre_init_net
,
365 static int proto_gre_net_init(struct net
*net
)
369 ret
= nf_ct_l4proto_pernet_register_one(net
,
370 &nf_conntrack_l4proto_gre4
);
372 pr_err("nf_conntrack_gre4: pernet registration failed.\n");
376 static void proto_gre_net_exit(struct net
*net
)
378 nf_ct_l4proto_pernet_unregister_one(net
, &nf_conntrack_l4proto_gre4
);
379 nf_ct_gre_keymap_flush(net
);
382 static struct pernet_operations proto_gre_net_ops
= {
383 .init
= proto_gre_net_init
,
384 .exit
= proto_gre_net_exit
,
385 .id
= &proto_gre_net_id
,
386 .size
= sizeof(struct netns_proto_gre
),
389 static int __init
nf_ct_proto_gre_init(void)
393 BUILD_BUG_ON(offsetof(struct netns_proto_gre
, nf
) != 0);
395 ret
= register_pernet_subsys(&proto_gre_net_ops
);
398 ret
= nf_ct_l4proto_register_one(&nf_conntrack_l4proto_gre4
);
404 unregister_pernet_subsys(&proto_gre_net_ops
);
409 static void __exit
nf_ct_proto_gre_fini(void)
411 nf_ct_l4proto_unregister_one(&nf_conntrack_l4proto_gre4
);
412 unregister_pernet_subsys(&proto_gre_net_ops
);
415 module_init(nf_ct_proto_gre_init
);
416 module_exit(nf_ct_proto_gre_fini
);
418 MODULE_LICENSE("GPL");