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>
35 #include <net/net_namespace.h>
36 #include <net/netns/generic.h>
37 #include <net/netfilter/nf_conntrack_l4proto.h>
38 #include <net/netfilter/nf_conntrack_helper.h>
39 #include <net/netfilter/nf_conntrack_core.h>
40 #include <linux/netfilter/nf_conntrack_proto_gre.h>
41 #include <linux/netfilter/nf_conntrack_pptp.h>
43 #define GRE_TIMEOUT (30 * HZ)
44 #define GRE_STREAM_TIMEOUT (180 * HZ)
46 static int proto_gre_net_id
;
47 struct netns_proto_gre
{
49 struct list_head keymap_list
;
52 void nf_ct_gre_keymap_flush(struct net
*net
)
54 struct netns_proto_gre
*net_gre
= net_generic(net
, proto_gre_net_id
);
55 struct nf_ct_gre_keymap
*km
, *tmp
;
57 write_lock_bh(&net_gre
->keymap_lock
);
58 list_for_each_entry_safe(km
, tmp
, &net_gre
->keymap_list
, list
) {
62 write_unlock_bh(&net_gre
->keymap_lock
);
64 EXPORT_SYMBOL(nf_ct_gre_keymap_flush
);
66 static inline int gre_key_cmpfn(const struct nf_ct_gre_keymap
*km
,
67 const struct nf_conntrack_tuple
*t
)
69 return km
->tuple
.src
.l3num
== t
->src
.l3num
&&
70 !memcmp(&km
->tuple
.src
.u3
, &t
->src
.u3
, sizeof(t
->src
.u3
)) &&
71 !memcmp(&km
->tuple
.dst
.u3
, &t
->dst
.u3
, sizeof(t
->dst
.u3
)) &&
72 km
->tuple
.dst
.protonum
== t
->dst
.protonum
&&
73 km
->tuple
.dst
.u
.all
== t
->dst
.u
.all
;
76 /* look up the source key for a given tuple */
77 static __be16
gre_keymap_lookup(struct net
*net
, struct nf_conntrack_tuple
*t
)
79 struct netns_proto_gre
*net_gre
= net_generic(net
, proto_gre_net_id
);
80 struct nf_ct_gre_keymap
*km
;
83 read_lock_bh(&net_gre
->keymap_lock
);
84 list_for_each_entry(km
, &net_gre
->keymap_list
, list
) {
85 if (gre_key_cmpfn(km
, t
)) {
86 key
= km
->tuple
.src
.u
.gre
.key
;
90 read_unlock_bh(&net_gre
->keymap_lock
);
92 pr_debug("lookup src key 0x%x for ", key
);
98 /* add a single keymap entry, associate with specified master ct */
99 int nf_ct_gre_keymap_add(struct nf_conn
*ct
, enum ip_conntrack_dir dir
,
100 struct nf_conntrack_tuple
*t
)
102 struct net
*net
= nf_ct_net(ct
);
103 struct netns_proto_gre
*net_gre
= net_generic(net
, proto_gre_net_id
);
104 struct nf_conn_help
*help
= nfct_help(ct
);
105 struct nf_ct_gre_keymap
**kmp
, *km
;
107 kmp
= &help
->help
.ct_pptp_info
.keymap
[dir
];
109 /* check whether it's a retransmission */
110 read_lock_bh(&net_gre
->keymap_lock
);
111 list_for_each_entry(km
, &net_gre
->keymap_list
, list
) {
112 if (gre_key_cmpfn(km
, t
) && km
== *kmp
) {
113 read_unlock_bh(&net_gre
->keymap_lock
);
117 read_unlock_bh(&net_gre
->keymap_lock
);
118 pr_debug("trying to override keymap_%s for ct %p\n",
119 dir
== IP_CT_DIR_REPLY
? "reply" : "orig", ct
);
123 km
= kmalloc(sizeof(*km
), GFP_ATOMIC
);
126 memcpy(&km
->tuple
, t
, sizeof(*t
));
129 pr_debug("adding new entry %p: ", km
);
130 nf_ct_dump_tuple(&km
->tuple
);
132 write_lock_bh(&net_gre
->keymap_lock
);
133 list_add_tail(&km
->list
, &net_gre
->keymap_list
);
134 write_unlock_bh(&net_gre
->keymap_lock
);
138 EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_add
);
140 /* destroy the keymap entries associated with specified master ct */
141 void nf_ct_gre_keymap_destroy(struct nf_conn
*ct
)
143 struct net
*net
= nf_ct_net(ct
);
144 struct netns_proto_gre
*net_gre
= net_generic(net
, proto_gre_net_id
);
145 struct nf_conn_help
*help
= nfct_help(ct
);
146 enum ip_conntrack_dir dir
;
148 pr_debug("entering for ct %p\n", ct
);
150 write_lock_bh(&net_gre
->keymap_lock
);
151 for (dir
= IP_CT_DIR_ORIGINAL
; dir
< IP_CT_DIR_MAX
; dir
++) {
152 if (help
->help
.ct_pptp_info
.keymap
[dir
]) {
153 pr_debug("removing %p from list\n",
154 help
->help
.ct_pptp_info
.keymap
[dir
]);
155 list_del(&help
->help
.ct_pptp_info
.keymap
[dir
]->list
);
156 kfree(help
->help
.ct_pptp_info
.keymap
[dir
]);
157 help
->help
.ct_pptp_info
.keymap
[dir
] = NULL
;
160 write_unlock_bh(&net_gre
->keymap_lock
);
162 EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_destroy
);
164 /* PUBLIC CONNTRACK PROTO HELPER FUNCTIONS */
166 /* invert gre part of tuple */
167 static bool gre_invert_tuple(struct nf_conntrack_tuple
*tuple
,
168 const struct nf_conntrack_tuple
*orig
)
170 tuple
->dst
.u
.gre
.key
= orig
->src
.u
.gre
.key
;
171 tuple
->src
.u
.gre
.key
= orig
->dst
.u
.gre
.key
;
175 /* gre hdr info to tuple */
176 static bool gre_pkt_to_tuple(const struct sk_buff
*skb
, unsigned int dataoff
,
177 struct nf_conntrack_tuple
*tuple
)
179 struct net
*net
= dev_net(skb
->dev
? skb
->dev
: skb
->dst
->dev
);
180 const struct gre_hdr_pptp
*pgrehdr
;
181 struct gre_hdr_pptp _pgrehdr
;
183 const struct gre_hdr
*grehdr
;
184 struct gre_hdr _grehdr
;
186 /* first only delinearize old RFC1701 GRE header */
187 grehdr
= skb_header_pointer(skb
, dataoff
, sizeof(_grehdr
), &_grehdr
);
188 if (!grehdr
|| grehdr
->version
!= GRE_VERSION_PPTP
) {
189 /* try to behave like "nf_conntrack_proto_generic" */
190 tuple
->src
.u
.all
= 0;
191 tuple
->dst
.u
.all
= 0;
195 /* PPTP header is variable length, only need up to the call_id field */
196 pgrehdr
= skb_header_pointer(skb
, dataoff
, 8, &_pgrehdr
);
200 if (ntohs(grehdr
->protocol
) != GRE_PROTOCOL_PPTP
) {
201 pr_debug("GRE_VERSION_PPTP but unknown proto\n");
205 tuple
->dst
.u
.gre
.key
= pgrehdr
->call_id
;
206 srckey
= gre_keymap_lookup(net
, tuple
);
207 tuple
->src
.u
.gre
.key
= srckey
;
212 /* print gre part of tuple */
213 static int gre_print_tuple(struct seq_file
*s
,
214 const struct nf_conntrack_tuple
*tuple
)
216 return seq_printf(s
, "srckey=0x%x dstkey=0x%x ",
217 ntohs(tuple
->src
.u
.gre
.key
),
218 ntohs(tuple
->dst
.u
.gre
.key
));
221 /* print private data for conntrack */
222 static int gre_print_conntrack(struct seq_file
*s
,
223 const struct nf_conn
*ct
)
225 return seq_printf(s
, "timeout=%u, stream_timeout=%u ",
226 (ct
->proto
.gre
.timeout
/ HZ
),
227 (ct
->proto
.gre
.stream_timeout
/ HZ
));
230 /* Returns verdict for packet, and may modify conntrack */
231 static int gre_packet(struct nf_conn
*ct
,
232 const struct sk_buff
*skb
,
233 unsigned int dataoff
,
234 enum ip_conntrack_info ctinfo
,
236 unsigned int hooknum
)
238 /* If we've seen traffic both ways, this is a GRE connection.
240 if (ct
->status
& IPS_SEEN_REPLY
) {
241 nf_ct_refresh_acct(ct
, ctinfo
, skb
,
242 ct
->proto
.gre
.stream_timeout
);
243 /* Also, more likely to be important, and not a probe. */
244 set_bit(IPS_ASSURED_BIT
, &ct
->status
);
245 nf_conntrack_event_cache(IPCT_STATUS
, ct
);
247 nf_ct_refresh_acct(ct
, ctinfo
, skb
,
248 ct
->proto
.gre
.timeout
);
253 /* Called when a new connection for this protocol found. */
254 static bool gre_new(struct nf_conn
*ct
, const struct sk_buff
*skb
,
255 unsigned int dataoff
)
258 nf_ct_dump_tuple(&ct
->tuplehash
[IP_CT_DIR_ORIGINAL
].tuple
);
260 /* initialize to sane value. Ideally a conntrack helper
261 * (e.g. in case of pptp) is increasing them */
262 ct
->proto
.gre
.stream_timeout
= GRE_STREAM_TIMEOUT
;
263 ct
->proto
.gre
.timeout
= GRE_TIMEOUT
;
268 /* Called when a conntrack entry has already been removed from the hashes
269 * and is about to be deleted from memory */
270 static void gre_destroy(struct nf_conn
*ct
)
272 struct nf_conn
*master
= ct
->master
;
273 pr_debug(" entering\n");
276 pr_debug("no master !?!\n");
278 nf_ct_gre_keymap_destroy(master
);
281 /* protocol helper struct */
282 static struct nf_conntrack_l4proto nf_conntrack_l4proto_gre4 __read_mostly
= {
284 .l4proto
= IPPROTO_GRE
,
286 .pkt_to_tuple
= gre_pkt_to_tuple
,
287 .invert_tuple
= gre_invert_tuple
,
288 .print_tuple
= gre_print_tuple
,
289 .print_conntrack
= gre_print_conntrack
,
290 .packet
= gre_packet
,
292 .destroy
= gre_destroy
,
294 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
295 .tuple_to_nlattr
= nf_ct_port_tuple_to_nlattr
,
296 .nlattr_to_tuple
= nf_ct_port_nlattr_to_tuple
,
297 .nla_policy
= nf_ct_port_nla_policy
,
301 static int proto_gre_net_init(struct net
*net
)
303 struct netns_proto_gre
*net_gre
;
306 net_gre
= kmalloc(sizeof(struct netns_proto_gre
), GFP_KERNEL
);
309 rwlock_init(&net_gre
->keymap_lock
);
310 INIT_LIST_HEAD(&net_gre
->keymap_list
);
312 rv
= net_assign_generic(net
, proto_gre_net_id
, net_gre
);
318 static void proto_gre_net_exit(struct net
*net
)
320 struct netns_proto_gre
*net_gre
= net_generic(net
, proto_gre_net_id
);
322 nf_ct_gre_keymap_flush(net
);
326 static struct pernet_operations proto_gre_net_ops
= {
327 .init
= proto_gre_net_init
,
328 .exit
= proto_gre_net_exit
,
331 static int __init
nf_ct_proto_gre_init(void)
335 rv
= nf_conntrack_l4proto_register(&nf_conntrack_l4proto_gre4
);
338 rv
= register_pernet_gen_subsys(&proto_gre_net_id
, &proto_gre_net_ops
);
340 nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_gre4
);
344 static void __exit
nf_ct_proto_gre_fini(void)
346 nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_gre4
);
347 unregister_pernet_gen_subsys(proto_gre_net_id
, &proto_gre_net_ops
);
350 module_init(nf_ct_proto_gre_init
);
351 module_exit(nf_ct_proto_gre_fini
);
353 MODULE_LICENSE("GPL");