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>
44 #define GRE_TIMEOUT (30 * HZ)
45 #define GRE_STREAM_TIMEOUT (180 * HZ)
47 static int proto_gre_net_id __read_mostly
;
48 struct netns_proto_gre
{
50 struct list_head keymap_list
;
53 void nf_ct_gre_keymap_flush(struct net
*net
)
55 struct netns_proto_gre
*net_gre
= net_generic(net
, proto_gre_net_id
);
56 struct nf_ct_gre_keymap
*km
, *tmp
;
58 write_lock_bh(&net_gre
->keymap_lock
);
59 list_for_each_entry_safe(km
, tmp
, &net_gre
->keymap_list
, list
) {
63 write_unlock_bh(&net_gre
->keymap_lock
);
65 EXPORT_SYMBOL(nf_ct_gre_keymap_flush
);
67 static inline int gre_key_cmpfn(const struct nf_ct_gre_keymap
*km
,
68 const struct nf_conntrack_tuple
*t
)
70 return km
->tuple
.src
.l3num
== t
->src
.l3num
&&
71 !memcmp(&km
->tuple
.src
.u3
, &t
->src
.u3
, sizeof(t
->src
.u3
)) &&
72 !memcmp(&km
->tuple
.dst
.u3
, &t
->dst
.u3
, sizeof(t
->dst
.u3
)) &&
73 km
->tuple
.dst
.protonum
== t
->dst
.protonum
&&
74 km
->tuple
.dst
.u
.all
== t
->dst
.u
.all
;
77 /* look up the source key for a given tuple */
78 static __be16
gre_keymap_lookup(struct net
*net
, struct nf_conntrack_tuple
*t
)
80 struct netns_proto_gre
*net_gre
= net_generic(net
, proto_gre_net_id
);
81 struct nf_ct_gre_keymap
*km
;
84 read_lock_bh(&net_gre
->keymap_lock
);
85 list_for_each_entry(km
, &net_gre
->keymap_list
, list
) {
86 if (gre_key_cmpfn(km
, t
)) {
87 key
= km
->tuple
.src
.u
.gre
.key
;
91 read_unlock_bh(&net_gre
->keymap_lock
);
93 pr_debug("lookup src key 0x%x for ", key
);
99 /* add a single keymap entry, associate with specified master ct */
100 int nf_ct_gre_keymap_add(struct nf_conn
*ct
, enum ip_conntrack_dir dir
,
101 struct nf_conntrack_tuple
*t
)
103 struct net
*net
= nf_ct_net(ct
);
104 struct netns_proto_gre
*net_gre
= net_generic(net
, proto_gre_net_id
);
105 struct nf_conn_help
*help
= nfct_help(ct
);
106 struct nf_ct_gre_keymap
**kmp
, *km
;
108 kmp
= &help
->help
.ct_pptp_info
.keymap
[dir
];
110 /* check whether it's a retransmission */
111 read_lock_bh(&net_gre
->keymap_lock
);
112 list_for_each_entry(km
, &net_gre
->keymap_list
, list
) {
113 if (gre_key_cmpfn(km
, t
) && km
== *kmp
) {
114 read_unlock_bh(&net_gre
->keymap_lock
);
118 read_unlock_bh(&net_gre
->keymap_lock
);
119 pr_debug("trying to override keymap_%s for ct %p\n",
120 dir
== IP_CT_DIR_REPLY
? "reply" : "orig", ct
);
124 km
= kmalloc(sizeof(*km
), GFP_ATOMIC
);
127 memcpy(&km
->tuple
, t
, sizeof(*t
));
130 pr_debug("adding new entry %p: ", km
);
131 nf_ct_dump_tuple(&km
->tuple
);
133 write_lock_bh(&net_gre
->keymap_lock
);
134 list_add_tail(&km
->list
, &net_gre
->keymap_list
);
135 write_unlock_bh(&net_gre
->keymap_lock
);
139 EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_add
);
141 /* destroy the keymap entries associated with specified master ct */
142 void nf_ct_gre_keymap_destroy(struct nf_conn
*ct
)
144 struct net
*net
= nf_ct_net(ct
);
145 struct netns_proto_gre
*net_gre
= net_generic(net
, proto_gre_net_id
);
146 struct nf_conn_help
*help
= nfct_help(ct
);
147 enum ip_conntrack_dir dir
;
149 pr_debug("entering for ct %p\n", ct
);
151 write_lock_bh(&net_gre
->keymap_lock
);
152 for (dir
= IP_CT_DIR_ORIGINAL
; dir
< IP_CT_DIR_MAX
; dir
++) {
153 if (help
->help
.ct_pptp_info
.keymap
[dir
]) {
154 pr_debug("removing %p from list\n",
155 help
->help
.ct_pptp_info
.keymap
[dir
]);
156 list_del(&help
->help
.ct_pptp_info
.keymap
[dir
]->list
);
157 kfree(help
->help
.ct_pptp_info
.keymap
[dir
]);
158 help
->help
.ct_pptp_info
.keymap
[dir
] = NULL
;
161 write_unlock_bh(&net_gre
->keymap_lock
);
163 EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_destroy
);
165 /* PUBLIC CONNTRACK PROTO HELPER FUNCTIONS */
167 /* invert gre part of tuple */
168 static bool gre_invert_tuple(struct nf_conntrack_tuple
*tuple
,
169 const struct nf_conntrack_tuple
*orig
)
171 tuple
->dst
.u
.gre
.key
= orig
->src
.u
.gre
.key
;
172 tuple
->src
.u
.gre
.key
= orig
->dst
.u
.gre
.key
;
176 /* gre hdr info to tuple */
177 static bool gre_pkt_to_tuple(const struct sk_buff
*skb
, unsigned int dataoff
,
178 struct nf_conntrack_tuple
*tuple
)
180 struct net
*net
= dev_net(skb
->dev
? skb
->dev
: skb_dst(skb
)->dev
);
181 const struct gre_hdr_pptp
*pgrehdr
;
182 struct gre_hdr_pptp _pgrehdr
;
184 const struct gre_hdr
*grehdr
;
185 struct gre_hdr _grehdr
;
187 /* first only delinearize old RFC1701 GRE header */
188 grehdr
= skb_header_pointer(skb
, dataoff
, sizeof(_grehdr
), &_grehdr
);
189 if (!grehdr
|| grehdr
->version
!= GRE_VERSION_PPTP
) {
190 /* try to behave like "nf_conntrack_proto_generic" */
191 tuple
->src
.u
.all
= 0;
192 tuple
->dst
.u
.all
= 0;
196 /* PPTP header is variable length, only need up to the call_id field */
197 pgrehdr
= skb_header_pointer(skb
, dataoff
, 8, &_pgrehdr
);
201 if (ntohs(grehdr
->protocol
) != GRE_PROTOCOL_PPTP
) {
202 pr_debug("GRE_VERSION_PPTP but unknown proto\n");
206 tuple
->dst
.u
.gre
.key
= pgrehdr
->call_id
;
207 srckey
= gre_keymap_lookup(net
, tuple
);
208 tuple
->src
.u
.gre
.key
= srckey
;
213 /* print gre part of tuple */
214 static int gre_print_tuple(struct seq_file
*s
,
215 const struct nf_conntrack_tuple
*tuple
)
217 return seq_printf(s
, "srckey=0x%x dstkey=0x%x ",
218 ntohs(tuple
->src
.u
.gre
.key
),
219 ntohs(tuple
->dst
.u
.gre
.key
));
222 /* print private data for conntrack */
223 static int gre_print_conntrack(struct seq_file
*s
, 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_ASSURED
, 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_tuple_size
= nf_ct_port_nlattr_tuple_size
,
297 .nlattr_to_tuple
= nf_ct_port_nlattr_to_tuple
,
298 .nla_policy
= nf_ct_port_nla_policy
,
302 static int proto_gre_net_init(struct net
*net
)
304 struct netns_proto_gre
*net_gre
= net_generic(net
, proto_gre_net_id
);
306 rwlock_init(&net_gre
->keymap_lock
);
307 INIT_LIST_HEAD(&net_gre
->keymap_list
);
312 static void proto_gre_net_exit(struct net
*net
)
314 nf_ct_gre_keymap_flush(net
);
317 static struct pernet_operations proto_gre_net_ops
= {
318 .init
= proto_gre_net_init
,
319 .exit
= proto_gre_net_exit
,
320 .id
= &proto_gre_net_id
,
321 .size
= sizeof(struct netns_proto_gre
),
324 static int __init
nf_ct_proto_gre_init(void)
328 rv
= nf_conntrack_l4proto_register(&nf_conntrack_l4proto_gre4
);
331 rv
= register_pernet_subsys(&proto_gre_net_ops
);
333 nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_gre4
);
337 static void __exit
nf_ct_proto_gre_fini(void)
339 nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_gre4
);
340 unregister_pernet_subsys(&proto_gre_net_ops
);
343 module_init(nf_ct_proto_gre_init
);
344 module_exit(nf_ct_proto_gre_fini
);
346 MODULE_LICENSE("GPL");