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/)
26 #include <linux/module.h>
27 #include <linux/types.h>
28 #include <linux/timer.h>
29 #include <linux/list.h>
30 #include <linux/seq_file.h>
32 #include <linux/netdevice.h>
33 #include <linux/skbuff.h>
34 #include <linux/slab.h>
36 #include <net/net_namespace.h>
37 #include <net/netns/generic.h>
38 #include <net/netfilter/nf_conntrack_l4proto.h>
39 #include <net/netfilter/nf_conntrack_helper.h>
40 #include <net/netfilter/nf_conntrack_core.h>
41 #include <linux/netfilter/nf_conntrack_proto_gre.h>
42 #include <linux/netfilter/nf_conntrack_pptp.h>
50 static unsigned int gre_timeouts
[GRE_CT_MAX
] = {
51 [GRE_CT_UNREPLIED
] = 30*HZ
,
52 [GRE_CT_REPLIED
] = 180*HZ
,
55 static int proto_gre_net_id __read_mostly
;
56 struct netns_proto_gre
{
57 struct nf_proto_net nf
;
59 struct list_head keymap_list
;
60 unsigned int gre_timeouts
[GRE_CT_MAX
];
63 static inline struct netns_proto_gre
*gre_pernet(struct net
*net
)
65 return net_generic(net
, proto_gre_net_id
);
68 void nf_ct_gre_keymap_flush(struct net
*net
)
70 struct netns_proto_gre
*net_gre
= gre_pernet(net
);
71 struct nf_ct_gre_keymap
*km
, *tmp
;
73 write_lock_bh(&net_gre
->keymap_lock
);
74 list_for_each_entry_safe(km
, tmp
, &net_gre
->keymap_list
, list
) {
78 write_unlock_bh(&net_gre
->keymap_lock
);
80 EXPORT_SYMBOL(nf_ct_gre_keymap_flush
);
82 static inline int gre_key_cmpfn(const struct nf_ct_gre_keymap
*km
,
83 const struct nf_conntrack_tuple
*t
)
85 return km
->tuple
.src
.l3num
== t
->src
.l3num
&&
86 !memcmp(&km
->tuple
.src
.u3
, &t
->src
.u3
, sizeof(t
->src
.u3
)) &&
87 !memcmp(&km
->tuple
.dst
.u3
, &t
->dst
.u3
, sizeof(t
->dst
.u3
)) &&
88 km
->tuple
.dst
.protonum
== t
->dst
.protonum
&&
89 km
->tuple
.dst
.u
.all
== t
->dst
.u
.all
;
92 /* look up the source key for a given tuple */
93 static __be16
gre_keymap_lookup(struct net
*net
, struct nf_conntrack_tuple
*t
)
95 struct netns_proto_gre
*net_gre
= gre_pernet(net
);
96 struct nf_ct_gre_keymap
*km
;
99 read_lock_bh(&net_gre
->keymap_lock
);
100 list_for_each_entry(km
, &net_gre
->keymap_list
, list
) {
101 if (gre_key_cmpfn(km
, t
)) {
102 key
= km
->tuple
.src
.u
.gre
.key
;
106 read_unlock_bh(&net_gre
->keymap_lock
);
108 pr_debug("lookup src key 0x%x for ", key
);
114 /* add a single keymap entry, associate with specified master ct */
115 int nf_ct_gre_keymap_add(struct nf_conn
*ct
, enum ip_conntrack_dir dir
,
116 struct nf_conntrack_tuple
*t
)
118 struct net
*net
= nf_ct_net(ct
);
119 struct netns_proto_gre
*net_gre
= gre_pernet(net
);
120 struct nf_ct_pptp_master
*ct_pptp_info
= nfct_help_data(ct
);
121 struct nf_ct_gre_keymap
**kmp
, *km
;
123 kmp
= &ct_pptp_info
->keymap
[dir
];
125 /* check whether it's a retransmission */
126 read_lock_bh(&net_gre
->keymap_lock
);
127 list_for_each_entry(km
, &net_gre
->keymap_list
, list
) {
128 if (gre_key_cmpfn(km
, t
) && km
== *kmp
) {
129 read_unlock_bh(&net_gre
->keymap_lock
);
133 read_unlock_bh(&net_gre
->keymap_lock
);
134 pr_debug("trying to override keymap_%s for ct %p\n",
135 dir
== IP_CT_DIR_REPLY
? "reply" : "orig", ct
);
139 km
= kmalloc(sizeof(*km
), GFP_ATOMIC
);
142 memcpy(&km
->tuple
, t
, sizeof(*t
));
145 pr_debug("adding new entry %p: ", km
);
146 nf_ct_dump_tuple(&km
->tuple
);
148 write_lock_bh(&net_gre
->keymap_lock
);
149 list_add_tail(&km
->list
, &net_gre
->keymap_list
);
150 write_unlock_bh(&net_gre
->keymap_lock
);
154 EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_add
);
156 /* destroy the keymap entries associated with specified master ct */
157 void nf_ct_gre_keymap_destroy(struct nf_conn
*ct
)
159 struct net
*net
= nf_ct_net(ct
);
160 struct netns_proto_gre
*net_gre
= gre_pernet(net
);
161 struct nf_ct_pptp_master
*ct_pptp_info
= nfct_help_data(ct
);
162 enum ip_conntrack_dir dir
;
164 pr_debug("entering for ct %p\n", ct
);
166 write_lock_bh(&net_gre
->keymap_lock
);
167 for (dir
= IP_CT_DIR_ORIGINAL
; dir
< IP_CT_DIR_MAX
; dir
++) {
168 if (ct_pptp_info
->keymap
[dir
]) {
169 pr_debug("removing %p from list\n",
170 ct_pptp_info
->keymap
[dir
]);
171 list_del(&ct_pptp_info
->keymap
[dir
]->list
);
172 kfree(ct_pptp_info
->keymap
[dir
]);
173 ct_pptp_info
->keymap
[dir
] = NULL
;
176 write_unlock_bh(&net_gre
->keymap_lock
);
178 EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_destroy
);
180 /* PUBLIC CONNTRACK PROTO HELPER FUNCTIONS */
182 /* invert gre part of tuple */
183 static bool gre_invert_tuple(struct nf_conntrack_tuple
*tuple
,
184 const struct nf_conntrack_tuple
*orig
)
186 tuple
->dst
.u
.gre
.key
= orig
->src
.u
.gre
.key
;
187 tuple
->src
.u
.gre
.key
= orig
->dst
.u
.gre
.key
;
191 /* gre hdr info to tuple */
192 static bool gre_pkt_to_tuple(const struct sk_buff
*skb
, unsigned int dataoff
,
193 struct nf_conntrack_tuple
*tuple
)
195 struct net
*net
= dev_net(skb
->dev
? skb
->dev
: skb_dst(skb
)->dev
);
196 const struct gre_hdr_pptp
*pgrehdr
;
197 struct gre_hdr_pptp _pgrehdr
;
199 const struct gre_hdr
*grehdr
;
200 struct gre_hdr _grehdr
;
202 /* first only delinearize old RFC1701 GRE header */
203 grehdr
= skb_header_pointer(skb
, dataoff
, sizeof(_grehdr
), &_grehdr
);
204 if (!grehdr
|| grehdr
->version
!= GRE_VERSION_PPTP
) {
205 /* try to behave like "nf_conntrack_proto_generic" */
206 tuple
->src
.u
.all
= 0;
207 tuple
->dst
.u
.all
= 0;
211 /* PPTP header is variable length, only need up to the call_id field */
212 pgrehdr
= skb_header_pointer(skb
, dataoff
, 8, &_pgrehdr
);
216 if (ntohs(grehdr
->protocol
) != GRE_PROTOCOL_PPTP
) {
217 pr_debug("GRE_VERSION_PPTP but unknown proto\n");
221 tuple
->dst
.u
.gre
.key
= pgrehdr
->call_id
;
222 srckey
= gre_keymap_lookup(net
, tuple
);
223 tuple
->src
.u
.gre
.key
= srckey
;
228 /* print gre part of tuple */
229 static int gre_print_tuple(struct seq_file
*s
,
230 const struct nf_conntrack_tuple
*tuple
)
232 return seq_printf(s
, "srckey=0x%x dstkey=0x%x ",
233 ntohs(tuple
->src
.u
.gre
.key
),
234 ntohs(tuple
->dst
.u
.gre
.key
));
237 /* print private data for conntrack */
238 static int gre_print_conntrack(struct seq_file
*s
, struct nf_conn
*ct
)
240 return seq_printf(s
, "timeout=%u, stream_timeout=%u ",
241 (ct
->proto
.gre
.timeout
/ HZ
),
242 (ct
->proto
.gre
.stream_timeout
/ HZ
));
245 static unsigned int *gre_get_timeouts(struct net
*net
)
247 return gre_pernet(net
)->gre_timeouts
;
250 /* Returns verdict for packet, and may modify conntrack */
251 static int gre_packet(struct nf_conn
*ct
,
252 const struct sk_buff
*skb
,
253 unsigned int dataoff
,
254 enum ip_conntrack_info ctinfo
,
256 unsigned int hooknum
,
257 unsigned int *timeouts
)
259 /* If we've seen traffic both ways, this is a GRE connection.
261 if (ct
->status
& IPS_SEEN_REPLY
) {
262 nf_ct_refresh_acct(ct
, ctinfo
, skb
,
263 ct
->proto
.gre
.stream_timeout
);
264 /* Also, more likely to be important, and not a probe. */
265 if (!test_and_set_bit(IPS_ASSURED_BIT
, &ct
->status
))
266 nf_conntrack_event_cache(IPCT_ASSURED
, ct
);
268 nf_ct_refresh_acct(ct
, ctinfo
, skb
,
269 ct
->proto
.gre
.timeout
);
274 /* Called when a new connection for this protocol found. */
275 static bool gre_new(struct nf_conn
*ct
, const struct sk_buff
*skb
,
276 unsigned int dataoff
, unsigned int *timeouts
)
279 nf_ct_dump_tuple(&ct
->tuplehash
[IP_CT_DIR_ORIGINAL
].tuple
);
281 /* initialize to sane value. Ideally a conntrack helper
282 * (e.g. in case of pptp) is increasing them */
283 ct
->proto
.gre
.stream_timeout
= timeouts
[GRE_CT_REPLIED
];
284 ct
->proto
.gre
.timeout
= timeouts
[GRE_CT_UNREPLIED
];
289 /* Called when a conntrack entry has already been removed from the hashes
290 * and is about to be deleted from memory */
291 static void gre_destroy(struct nf_conn
*ct
)
293 struct nf_conn
*master
= ct
->master
;
294 pr_debug(" entering\n");
297 pr_debug("no master !?!\n");
299 nf_ct_gre_keymap_destroy(master
);
302 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
304 #include <linux/netfilter/nfnetlink.h>
305 #include <linux/netfilter/nfnetlink_cttimeout.h>
307 static int gre_timeout_nlattr_to_obj(struct nlattr
*tb
[],
308 struct net
*net
, void *data
)
310 unsigned int *timeouts
= data
;
311 struct netns_proto_gre
*net_gre
= gre_pernet(net
);
313 /* set default timeouts for GRE. */
314 timeouts
[GRE_CT_UNREPLIED
] = net_gre
->gre_timeouts
[GRE_CT_UNREPLIED
];
315 timeouts
[GRE_CT_REPLIED
] = net_gre
->gre_timeouts
[GRE_CT_REPLIED
];
317 if (tb
[CTA_TIMEOUT_GRE_UNREPLIED
]) {
318 timeouts
[GRE_CT_UNREPLIED
] =
319 ntohl(nla_get_be32(tb
[CTA_TIMEOUT_GRE_UNREPLIED
])) * HZ
;
321 if (tb
[CTA_TIMEOUT_GRE_REPLIED
]) {
322 timeouts
[GRE_CT_REPLIED
] =
323 ntohl(nla_get_be32(tb
[CTA_TIMEOUT_GRE_REPLIED
])) * HZ
;
329 gre_timeout_obj_to_nlattr(struct sk_buff
*skb
, const void *data
)
331 const unsigned int *timeouts
= data
;
333 if (nla_put_be32(skb
, CTA_TIMEOUT_GRE_UNREPLIED
,
334 htonl(timeouts
[GRE_CT_UNREPLIED
] / HZ
)) ||
335 nla_put_be32(skb
, CTA_TIMEOUT_GRE_REPLIED
,
336 htonl(timeouts
[GRE_CT_REPLIED
] / HZ
)))
337 goto nla_put_failure
;
344 static const struct nla_policy
345 gre_timeout_nla_policy
[CTA_TIMEOUT_GRE_MAX
+1] = {
346 [CTA_TIMEOUT_GRE_UNREPLIED
] = { .type
= NLA_U32
},
347 [CTA_TIMEOUT_GRE_REPLIED
] = { .type
= NLA_U32
},
349 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
351 static int gre_init_net(struct net
*net
, u_int16_t proto
)
353 struct netns_proto_gre
*net_gre
= gre_pernet(net
);
356 rwlock_init(&net_gre
->keymap_lock
);
357 INIT_LIST_HEAD(&net_gre
->keymap_list
);
358 for (i
= 0; i
< GRE_CT_MAX
; i
++)
359 net_gre
->gre_timeouts
[i
] = gre_timeouts
[i
];
364 /* protocol helper struct */
365 static struct nf_conntrack_l4proto nf_conntrack_l4proto_gre4 __read_mostly
= {
367 .l4proto
= IPPROTO_GRE
,
369 .pkt_to_tuple
= gre_pkt_to_tuple
,
370 .invert_tuple
= gre_invert_tuple
,
371 .print_tuple
= gre_print_tuple
,
372 .print_conntrack
= gre_print_conntrack
,
373 .get_timeouts
= gre_get_timeouts
,
374 .packet
= gre_packet
,
376 .destroy
= gre_destroy
,
378 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
379 .tuple_to_nlattr
= nf_ct_port_tuple_to_nlattr
,
380 .nlattr_tuple_size
= nf_ct_port_nlattr_tuple_size
,
381 .nlattr_to_tuple
= nf_ct_port_nlattr_to_tuple
,
382 .nla_policy
= nf_ct_port_nla_policy
,
384 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
386 .nlattr_to_obj
= gre_timeout_nlattr_to_obj
,
387 .obj_to_nlattr
= gre_timeout_obj_to_nlattr
,
388 .nlattr_max
= CTA_TIMEOUT_GRE_MAX
,
389 .obj_size
= sizeof(unsigned int) * GRE_CT_MAX
,
390 .nla_policy
= gre_timeout_nla_policy
,
392 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
393 .net_id
= &proto_gre_net_id
,
394 .init_net
= gre_init_net
,
397 static int proto_gre_net_init(struct net
*net
)
400 ret
= nf_conntrack_l4proto_register(net
, &nf_conntrack_l4proto_gre4
);
402 pr_err("nf_conntrack_l4proto_gre4 :protocol register failed.\n");
406 static void proto_gre_net_exit(struct net
*net
)
408 nf_conntrack_l4proto_unregister(net
, &nf_conntrack_l4proto_gre4
);
409 nf_ct_gre_keymap_flush(net
);
412 static struct pernet_operations proto_gre_net_ops
= {
413 .init
= proto_gre_net_init
,
414 .exit
= proto_gre_net_exit
,
415 .id
= &proto_gre_net_id
,
416 .size
= sizeof(struct netns_proto_gre
),
419 static int __init
nf_ct_proto_gre_init(void)
421 return register_pernet_subsys(&proto_gre_net_ops
);
424 static void __exit
nf_ct_proto_gre_fini(void)
426 unregister_pernet_subsys(&proto_gre_net_ops
);
429 module_init(nf_ct_proto_gre_init
);
430 module_exit(nf_ct_proto_gre_fini
);
432 MODULE_LICENSE("GPL");