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 <linux/netfilter/nf_conntrack_proto_gre.h>
43 #include <linux/netfilter/nf_conntrack_pptp.h>
51 static unsigned int gre_timeouts
[GRE_CT_MAX
] = {
52 [GRE_CT_UNREPLIED
] = 30*HZ
,
53 [GRE_CT_REPLIED
] = 180*HZ
,
56 static int proto_gre_net_id __read_mostly
;
57 struct netns_proto_gre
{
58 struct nf_proto_net nf
;
60 struct list_head keymap_list
;
61 unsigned int gre_timeouts
[GRE_CT_MAX
];
64 static inline struct netns_proto_gre
*gre_pernet(struct net
*net
)
66 return net_generic(net
, proto_gre_net_id
);
69 void nf_ct_gre_keymap_flush(struct net
*net
)
71 struct netns_proto_gre
*net_gre
= gre_pernet(net
);
72 struct nf_ct_gre_keymap
*km
, *tmp
;
74 write_lock_bh(&net_gre
->keymap_lock
);
75 list_for_each_entry_safe(km
, tmp
, &net_gre
->keymap_list
, list
) {
79 write_unlock_bh(&net_gre
->keymap_lock
);
81 EXPORT_SYMBOL(nf_ct_gre_keymap_flush
);
83 static inline int gre_key_cmpfn(const struct nf_ct_gre_keymap
*km
,
84 const struct nf_conntrack_tuple
*t
)
86 return km
->tuple
.src
.l3num
== t
->src
.l3num
&&
87 !memcmp(&km
->tuple
.src
.u3
, &t
->src
.u3
, sizeof(t
->src
.u3
)) &&
88 !memcmp(&km
->tuple
.dst
.u3
, &t
->dst
.u3
, sizeof(t
->dst
.u3
)) &&
89 km
->tuple
.dst
.protonum
== t
->dst
.protonum
&&
90 km
->tuple
.dst
.u
.all
== t
->dst
.u
.all
;
93 /* look up the source key for a given tuple */
94 static __be16
gre_keymap_lookup(struct net
*net
, struct nf_conntrack_tuple
*t
)
96 struct netns_proto_gre
*net_gre
= gre_pernet(net
);
97 struct nf_ct_gre_keymap
*km
;
100 read_lock_bh(&net_gre
->keymap_lock
);
101 list_for_each_entry(km
, &net_gre
->keymap_list
, list
) {
102 if (gre_key_cmpfn(km
, t
)) {
103 key
= km
->tuple
.src
.u
.gre
.key
;
107 read_unlock_bh(&net_gre
->keymap_lock
);
109 pr_debug("lookup src key 0x%x for ", key
);
115 /* add a single keymap entry, associate with specified master ct */
116 int nf_ct_gre_keymap_add(struct nf_conn
*ct
, enum ip_conntrack_dir dir
,
117 struct nf_conntrack_tuple
*t
)
119 struct net
*net
= nf_ct_net(ct
);
120 struct netns_proto_gre
*net_gre
= gre_pernet(net
);
121 struct nf_ct_pptp_master
*ct_pptp_info
= nfct_help_data(ct
);
122 struct nf_ct_gre_keymap
**kmp
, *km
;
124 kmp
= &ct_pptp_info
->keymap
[dir
];
126 /* check whether it's a retransmission */
127 read_lock_bh(&net_gre
->keymap_lock
);
128 list_for_each_entry(km
, &net_gre
->keymap_list
, list
) {
129 if (gre_key_cmpfn(km
, t
) && km
== *kmp
) {
130 read_unlock_bh(&net_gre
->keymap_lock
);
134 read_unlock_bh(&net_gre
->keymap_lock
);
135 pr_debug("trying to override keymap_%s for ct %p\n",
136 dir
== IP_CT_DIR_REPLY
? "reply" : "orig", ct
);
140 km
= kmalloc(sizeof(*km
), GFP_ATOMIC
);
143 memcpy(&km
->tuple
, t
, sizeof(*t
));
146 pr_debug("adding new entry %p: ", km
);
147 nf_ct_dump_tuple(&km
->tuple
);
149 write_lock_bh(&net_gre
->keymap_lock
);
150 list_add_tail(&km
->list
, &net_gre
->keymap_list
);
151 write_unlock_bh(&net_gre
->keymap_lock
);
155 EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_add
);
157 /* destroy the keymap entries associated with specified master ct */
158 void nf_ct_gre_keymap_destroy(struct nf_conn
*ct
)
160 struct net
*net
= nf_ct_net(ct
);
161 struct netns_proto_gre
*net_gre
= gre_pernet(net
);
162 struct nf_ct_pptp_master
*ct_pptp_info
= nfct_help_data(ct
);
163 enum ip_conntrack_dir dir
;
165 pr_debug("entering for ct %p\n", ct
);
167 write_lock_bh(&net_gre
->keymap_lock
);
168 for (dir
= IP_CT_DIR_ORIGINAL
; dir
< IP_CT_DIR_MAX
; dir
++) {
169 if (ct_pptp_info
->keymap
[dir
]) {
170 pr_debug("removing %p from list\n",
171 ct_pptp_info
->keymap
[dir
]);
172 list_del(&ct_pptp_info
->keymap
[dir
]->list
);
173 kfree(ct_pptp_info
->keymap
[dir
]);
174 ct_pptp_info
->keymap
[dir
] = NULL
;
177 write_unlock_bh(&net_gre
->keymap_lock
);
179 EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_destroy
);
181 /* PUBLIC CONNTRACK PROTO HELPER FUNCTIONS */
183 /* invert gre part of tuple */
184 static bool gre_invert_tuple(struct nf_conntrack_tuple
*tuple
,
185 const struct nf_conntrack_tuple
*orig
)
187 tuple
->dst
.u
.gre
.key
= orig
->src
.u
.gre
.key
;
188 tuple
->src
.u
.gre
.key
= orig
->dst
.u
.gre
.key
;
192 /* gre hdr info to tuple */
193 static bool gre_pkt_to_tuple(const struct sk_buff
*skb
, unsigned int dataoff
,
194 struct nf_conntrack_tuple
*tuple
)
196 struct net
*net
= dev_net(skb
->dev
? skb
->dev
: skb_dst(skb
)->dev
);
197 const struct gre_hdr_pptp
*pgrehdr
;
198 struct gre_hdr_pptp _pgrehdr
;
200 const struct gre_hdr
*grehdr
;
201 struct gre_hdr _grehdr
;
203 /* first only delinearize old RFC1701 GRE header */
204 grehdr
= skb_header_pointer(skb
, dataoff
, sizeof(_grehdr
), &_grehdr
);
205 if (!grehdr
|| grehdr
->version
!= GRE_VERSION_PPTP
) {
206 /* try to behave like "nf_conntrack_proto_generic" */
207 tuple
->src
.u
.all
= 0;
208 tuple
->dst
.u
.all
= 0;
212 /* PPTP header is variable length, only need up to the call_id field */
213 pgrehdr
= skb_header_pointer(skb
, dataoff
, 8, &_pgrehdr
);
217 if (ntohs(grehdr
->protocol
) != GRE_PROTOCOL_PPTP
) {
218 pr_debug("GRE_VERSION_PPTP but unknown proto\n");
222 tuple
->dst
.u
.gre
.key
= pgrehdr
->call_id
;
223 srckey
= gre_keymap_lookup(net
, tuple
);
224 tuple
->src
.u
.gre
.key
= srckey
;
229 /* print gre part of tuple */
230 static int gre_print_tuple(struct seq_file
*s
,
231 const struct nf_conntrack_tuple
*tuple
)
233 return seq_printf(s
, "srckey=0x%x dstkey=0x%x ",
234 ntohs(tuple
->src
.u
.gre
.key
),
235 ntohs(tuple
->dst
.u
.gre
.key
));
238 /* print private data for conntrack */
239 static int gre_print_conntrack(struct seq_file
*s
, struct nf_conn
*ct
)
241 return seq_printf(s
, "timeout=%u, stream_timeout=%u ",
242 (ct
->proto
.gre
.timeout
/ HZ
),
243 (ct
->proto
.gre
.stream_timeout
/ HZ
));
246 static unsigned int *gre_get_timeouts(struct net
*net
)
248 return gre_pernet(net
)->gre_timeouts
;
251 /* Returns verdict for packet, and may modify conntrack */
252 static int gre_packet(struct nf_conn
*ct
,
253 const struct sk_buff
*skb
,
254 unsigned int dataoff
,
255 enum ip_conntrack_info ctinfo
,
257 unsigned int hooknum
,
258 unsigned int *timeouts
)
260 /* If we've seen traffic both ways, this is a GRE connection.
262 if (ct
->status
& IPS_SEEN_REPLY
) {
263 nf_ct_refresh_acct(ct
, ctinfo
, skb
,
264 ct
->proto
.gre
.stream_timeout
);
265 /* Also, more likely to be important, and not a probe. */
266 if (!test_and_set_bit(IPS_ASSURED_BIT
, &ct
->status
))
267 nf_conntrack_event_cache(IPCT_ASSURED
, ct
);
269 nf_ct_refresh_acct(ct
, ctinfo
, skb
,
270 ct
->proto
.gre
.timeout
);
275 /* Called when a new connection for this protocol found. */
276 static bool gre_new(struct nf_conn
*ct
, const struct sk_buff
*skb
,
277 unsigned int dataoff
, unsigned int *timeouts
)
280 nf_ct_dump_tuple(&ct
->tuplehash
[IP_CT_DIR_ORIGINAL
].tuple
);
282 /* initialize to sane value. Ideally a conntrack helper
283 * (e.g. in case of pptp) is increasing them */
284 ct
->proto
.gre
.stream_timeout
= timeouts
[GRE_CT_REPLIED
];
285 ct
->proto
.gre
.timeout
= timeouts
[GRE_CT_UNREPLIED
];
290 /* Called when a conntrack entry has already been removed from the hashes
291 * and is about to be deleted from memory */
292 static void gre_destroy(struct nf_conn
*ct
)
294 struct nf_conn
*master
= ct
->master
;
295 pr_debug(" entering\n");
298 pr_debug("no master !?!\n");
300 nf_ct_gre_keymap_destroy(master
);
303 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
305 #include <linux/netfilter/nfnetlink.h>
306 #include <linux/netfilter/nfnetlink_cttimeout.h>
308 static int gre_timeout_nlattr_to_obj(struct nlattr
*tb
[],
309 struct net
*net
, void *data
)
311 unsigned int *timeouts
= data
;
312 struct netns_proto_gre
*net_gre
= gre_pernet(net
);
314 /* set default timeouts for GRE. */
315 timeouts
[GRE_CT_UNREPLIED
] = net_gre
->gre_timeouts
[GRE_CT_UNREPLIED
];
316 timeouts
[GRE_CT_REPLIED
] = net_gre
->gre_timeouts
[GRE_CT_REPLIED
];
318 if (tb
[CTA_TIMEOUT_GRE_UNREPLIED
]) {
319 timeouts
[GRE_CT_UNREPLIED
] =
320 ntohl(nla_get_be32(tb
[CTA_TIMEOUT_GRE_UNREPLIED
])) * HZ
;
322 if (tb
[CTA_TIMEOUT_GRE_REPLIED
]) {
323 timeouts
[GRE_CT_REPLIED
] =
324 ntohl(nla_get_be32(tb
[CTA_TIMEOUT_GRE_REPLIED
])) * HZ
;
330 gre_timeout_obj_to_nlattr(struct sk_buff
*skb
, const void *data
)
332 const unsigned int *timeouts
= data
;
334 if (nla_put_be32(skb
, CTA_TIMEOUT_GRE_UNREPLIED
,
335 htonl(timeouts
[GRE_CT_UNREPLIED
] / HZ
)) ||
336 nla_put_be32(skb
, CTA_TIMEOUT_GRE_REPLIED
,
337 htonl(timeouts
[GRE_CT_REPLIED
] / HZ
)))
338 goto nla_put_failure
;
345 static const struct nla_policy
346 gre_timeout_nla_policy
[CTA_TIMEOUT_GRE_MAX
+1] = {
347 [CTA_TIMEOUT_GRE_UNREPLIED
] = { .type
= NLA_U32
},
348 [CTA_TIMEOUT_GRE_REPLIED
] = { .type
= NLA_U32
},
350 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
352 static int gre_init_net(struct net
*net
, u_int16_t proto
)
354 struct netns_proto_gre
*net_gre
= gre_pernet(net
);
357 rwlock_init(&net_gre
->keymap_lock
);
358 INIT_LIST_HEAD(&net_gre
->keymap_list
);
359 for (i
= 0; i
< GRE_CT_MAX
; i
++)
360 net_gre
->gre_timeouts
[i
] = gre_timeouts
[i
];
365 /* protocol helper struct */
366 static struct nf_conntrack_l4proto nf_conntrack_l4proto_gre4 __read_mostly
= {
368 .l4proto
= IPPROTO_GRE
,
370 .pkt_to_tuple
= gre_pkt_to_tuple
,
371 .invert_tuple
= gre_invert_tuple
,
372 .print_tuple
= gre_print_tuple
,
373 .print_conntrack
= gre_print_conntrack
,
374 .get_timeouts
= gre_get_timeouts
,
375 .packet
= gre_packet
,
377 .destroy
= gre_destroy
,
379 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
380 .tuple_to_nlattr
= nf_ct_port_tuple_to_nlattr
,
381 .nlattr_tuple_size
= nf_ct_port_nlattr_tuple_size
,
382 .nlattr_to_tuple
= nf_ct_port_nlattr_to_tuple
,
383 .nla_policy
= nf_ct_port_nla_policy
,
385 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
387 .nlattr_to_obj
= gre_timeout_nlattr_to_obj
,
388 .obj_to_nlattr
= gre_timeout_obj_to_nlattr
,
389 .nlattr_max
= CTA_TIMEOUT_GRE_MAX
,
390 .obj_size
= sizeof(unsigned int) * GRE_CT_MAX
,
391 .nla_policy
= gre_timeout_nla_policy
,
393 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
394 .net_id
= &proto_gre_net_id
,
395 .init_net
= gre_init_net
,
398 static int proto_gre_net_init(struct net
*net
)
401 ret
= nf_ct_l4proto_pernet_register(net
, &nf_conntrack_l4proto_gre4
);
403 pr_err("nf_conntrack_gre4: pernet registration failed.\n");
407 static void proto_gre_net_exit(struct net
*net
)
409 nf_ct_l4proto_pernet_unregister(net
, &nf_conntrack_l4proto_gre4
);
410 nf_ct_gre_keymap_flush(net
);
413 static struct pernet_operations proto_gre_net_ops
= {
414 .init
= proto_gre_net_init
,
415 .exit
= proto_gre_net_exit
,
416 .id
= &proto_gre_net_id
,
417 .size
= sizeof(struct netns_proto_gre
),
420 static int __init
nf_ct_proto_gre_init(void)
424 ret
= register_pernet_subsys(&proto_gre_net_ops
);
428 ret
= nf_ct_l4proto_register(&nf_conntrack_l4proto_gre4
);
434 unregister_pernet_subsys(&proto_gre_net_ops
);
439 static void __exit
nf_ct_proto_gre_fini(void)
441 nf_ct_l4proto_unregister(&nf_conntrack_l4proto_gre4
);
442 unregister_pernet_subsys(&proto_gre_net_ops
);
445 module_init(nf_ct_proto_gre_init
);
446 module_exit(nf_ct_proto_gre_fini
);
448 MODULE_LICENSE("GPL");