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f09943fe PM |
1 | /* |
2 | * ip_conntrack_proto_gre.c - Version 3.0 | |
3 | * | |
4 | * Connection tracking protocol helper module for GRE. | |
5 | * | |
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. | |
8 | * | |
9 | * It has an optional key field, which may help us distinguishing two | |
10 | * connections between the same two hosts. | |
11 | * | |
12 | * GRE is defined in RFC 1701 and RFC 1702, as well as RFC 2784 | |
13 | * | |
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 | |
16 | * field in plain GRE. | |
17 | * | |
18 | * Documentation about PPTP can be found in RFC 2637 | |
19 | * | |
20 | * (C) 2000-2005 by Harald Welte <laforge@gnumonks.org> | |
21 | * | |
22 | * Development of this code funded by Astaro AG (http://www.astaro.com/) | |
23 | * | |
24 | */ | |
25 | ||
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> | |
31 | #include <linux/in.h> | |
3bb0d1c0 | 32 | #include <linux/netdevice.h> |
f09943fe | 33 | #include <linux/skbuff.h> |
3bb0d1c0 AD |
34 | #include <net/dst.h> |
35 | #include <net/net_namespace.h> | |
36 | #include <net/netns/generic.h> | |
f09943fe PM |
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> | |
42 | ||
43 | #define GRE_TIMEOUT (30 * HZ) | |
44 | #define GRE_STREAM_TIMEOUT (180 * HZ) | |
45 | ||
3bb0d1c0 AD |
46 | static int proto_gre_net_id; |
47 | struct netns_proto_gre { | |
48 | rwlock_t keymap_lock; | |
49 | struct list_head keymap_list; | |
50 | }; | |
f09943fe | 51 | |
3bb0d1c0 | 52 | void nf_ct_gre_keymap_flush(struct net *net) |
f09943fe | 53 | { |
3bb0d1c0 | 54 | struct netns_proto_gre *net_gre = net_generic(net, proto_gre_net_id); |
51807e91 | 55 | struct nf_ct_gre_keymap *km, *tmp; |
f09943fe | 56 | |
3bb0d1c0 AD |
57 | write_lock_bh(&net_gre->keymap_lock); |
58 | list_for_each_entry_safe(km, tmp, &net_gre->keymap_list, list) { | |
51807e91 AD |
59 | list_del(&km->list); |
60 | kfree(km); | |
f09943fe | 61 | } |
3bb0d1c0 | 62 | write_unlock_bh(&net_gre->keymap_lock); |
f09943fe PM |
63 | } |
64 | EXPORT_SYMBOL(nf_ct_gre_keymap_flush); | |
65 | ||
66 | static inline int gre_key_cmpfn(const struct nf_ct_gre_keymap *km, | |
67 | const struct nf_conntrack_tuple *t) | |
68 | { | |
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; | |
74 | } | |
75 | ||
76 | /* look up the source key for a given tuple */ | |
3bb0d1c0 | 77 | static __be16 gre_keymap_lookup(struct net *net, struct nf_conntrack_tuple *t) |
f09943fe | 78 | { |
3bb0d1c0 | 79 | struct netns_proto_gre *net_gre = net_generic(net, proto_gre_net_id); |
f09943fe PM |
80 | struct nf_ct_gre_keymap *km; |
81 | __be16 key = 0; | |
82 | ||
3bb0d1c0 AD |
83 | read_lock_bh(&net_gre->keymap_lock); |
84 | list_for_each_entry(km, &net_gre->keymap_list, list) { | |
f09943fe PM |
85 | if (gre_key_cmpfn(km, t)) { |
86 | key = km->tuple.src.u.gre.key; | |
87 | break; | |
88 | } | |
89 | } | |
3bb0d1c0 | 90 | read_unlock_bh(&net_gre->keymap_lock); |
f09943fe | 91 | |
0d53778e | 92 | pr_debug("lookup src key 0x%x for ", key); |
3c9fba65 | 93 | nf_ct_dump_tuple(t); |
f09943fe PM |
94 | |
95 | return key; | |
96 | } | |
97 | ||
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) | |
101 | { | |
3bb0d1c0 AD |
102 | struct net *net = nf_ct_net(ct); |
103 | struct netns_proto_gre *net_gre = net_generic(net, proto_gre_net_id); | |
f09943fe PM |
104 | struct nf_conn_help *help = nfct_help(ct); |
105 | struct nf_ct_gre_keymap **kmp, *km; | |
106 | ||
f09943fe PM |
107 | kmp = &help->help.ct_pptp_info.keymap[dir]; |
108 | if (*kmp) { | |
109 | /* check whether it's a retransmission */ | |
3bb0d1c0 AD |
110 | read_lock_bh(&net_gre->keymap_lock); |
111 | list_for_each_entry(km, &net_gre->keymap_list, list) { | |
887464a4 | 112 | if (gre_key_cmpfn(km, t) && km == *kmp) { |
3bb0d1c0 | 113 | read_unlock_bh(&net_gre->keymap_lock); |
f09943fe | 114 | return 0; |
887464a4 | 115 | } |
f09943fe | 116 | } |
3bb0d1c0 | 117 | read_unlock_bh(&net_gre->keymap_lock); |
0d53778e PM |
118 | pr_debug("trying to override keymap_%s for ct %p\n", |
119 | dir == IP_CT_DIR_REPLY ? "reply" : "orig", ct); | |
f09943fe PM |
120 | return -EEXIST; |
121 | } | |
122 | ||
123 | km = kmalloc(sizeof(*km), GFP_ATOMIC); | |
124 | if (!km) | |
125 | return -ENOMEM; | |
126 | memcpy(&km->tuple, t, sizeof(*t)); | |
127 | *kmp = km; | |
128 | ||
0d53778e | 129 | pr_debug("adding new entry %p: ", km); |
3c9fba65 | 130 | nf_ct_dump_tuple(&km->tuple); |
f09943fe | 131 | |
3bb0d1c0 AD |
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); | |
f09943fe PM |
135 | |
136 | return 0; | |
137 | } | |
138 | EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_add); | |
139 | ||
140 | /* destroy the keymap entries associated with specified master ct */ | |
141 | void nf_ct_gre_keymap_destroy(struct nf_conn *ct) | |
142 | { | |
3bb0d1c0 AD |
143 | struct net *net = nf_ct_net(ct); |
144 | struct netns_proto_gre *net_gre = net_generic(net, proto_gre_net_id); | |
f09943fe PM |
145 | struct nf_conn_help *help = nfct_help(ct); |
146 | enum ip_conntrack_dir dir; | |
147 | ||
0d53778e | 148 | pr_debug("entering for ct %p\n", ct); |
f09943fe | 149 | |
3bb0d1c0 | 150 | write_lock_bh(&net_gre->keymap_lock); |
f09943fe PM |
151 | for (dir = IP_CT_DIR_ORIGINAL; dir < IP_CT_DIR_MAX; dir++) { |
152 | if (help->help.ct_pptp_info.keymap[dir]) { | |
0d53778e PM |
153 | pr_debug("removing %p from list\n", |
154 | help->help.ct_pptp_info.keymap[dir]); | |
f09943fe PM |
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; | |
158 | } | |
159 | } | |
3bb0d1c0 | 160 | write_unlock_bh(&net_gre->keymap_lock); |
f09943fe PM |
161 | } |
162 | EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_destroy); | |
163 | ||
164 | /* PUBLIC CONNTRACK PROTO HELPER FUNCTIONS */ | |
165 | ||
166 | /* invert gre part of tuple */ | |
09f263cd JE |
167 | static bool gre_invert_tuple(struct nf_conntrack_tuple *tuple, |
168 | const struct nf_conntrack_tuple *orig) | |
f09943fe PM |
169 | { |
170 | tuple->dst.u.gre.key = orig->src.u.gre.key; | |
171 | tuple->src.u.gre.key = orig->dst.u.gre.key; | |
09f263cd | 172 | return true; |
f09943fe PM |
173 | } |
174 | ||
175 | /* gre hdr info to tuple */ | |
09f263cd JE |
176 | static bool gre_pkt_to_tuple(const struct sk_buff *skb, unsigned int dataoff, |
177 | struct nf_conntrack_tuple *tuple) | |
f09943fe | 178 | { |
adf30907 | 179 | struct net *net = dev_net(skb->dev ? skb->dev : skb_dst(skb)->dev); |
dc35dc5a JE |
180 | const struct gre_hdr_pptp *pgrehdr; |
181 | struct gre_hdr_pptp _pgrehdr; | |
f09943fe | 182 | __be16 srckey; |
dc35dc5a JE |
183 | const struct gre_hdr *grehdr; |
184 | struct gre_hdr _grehdr; | |
f09943fe PM |
185 | |
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; | |
09f263cd | 192 | return true; |
f09943fe PM |
193 | } |
194 | ||
195 | /* PPTP header is variable length, only need up to the call_id field */ | |
196 | pgrehdr = skb_header_pointer(skb, dataoff, 8, &_pgrehdr); | |
197 | if (!pgrehdr) | |
09f263cd | 198 | return true; |
f09943fe PM |
199 | |
200 | if (ntohs(grehdr->protocol) != GRE_PROTOCOL_PPTP) { | |
0d53778e | 201 | pr_debug("GRE_VERSION_PPTP but unknown proto\n"); |
09f263cd | 202 | return false; |
f09943fe PM |
203 | } |
204 | ||
205 | tuple->dst.u.gre.key = pgrehdr->call_id; | |
3bb0d1c0 | 206 | srckey = gre_keymap_lookup(net, tuple); |
f09943fe PM |
207 | tuple->src.u.gre.key = srckey; |
208 | ||
09f263cd | 209 | return true; |
f09943fe PM |
210 | } |
211 | ||
212 | /* print gre part of tuple */ | |
213 | static int gre_print_tuple(struct seq_file *s, | |
214 | const struct nf_conntrack_tuple *tuple) | |
215 | { | |
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)); | |
219 | } | |
220 | ||
221 | /* print private data for conntrack */ | |
440f0d58 | 222 | static int gre_print_conntrack(struct seq_file *s, struct nf_conn *ct) |
f09943fe PM |
223 | { |
224 | return seq_printf(s, "timeout=%u, stream_timeout=%u ", | |
225 | (ct->proto.gre.timeout / HZ), | |
226 | (ct->proto.gre.stream_timeout / HZ)); | |
227 | } | |
228 | ||
229 | /* Returns verdict for packet, and may modify conntrack */ | |
230 | static int gre_packet(struct nf_conn *ct, | |
231 | const struct sk_buff *skb, | |
232 | unsigned int dataoff, | |
233 | enum ip_conntrack_info ctinfo, | |
76108cea | 234 | u_int8_t pf, |
f09943fe PM |
235 | unsigned int hooknum) |
236 | { | |
237 | /* If we've seen traffic both ways, this is a GRE connection. | |
238 | * Extend timeout. */ | |
239 | if (ct->status & IPS_SEEN_REPLY) { | |
240 | nf_ct_refresh_acct(ct, ctinfo, skb, | |
241 | ct->proto.gre.stream_timeout); | |
242 | /* Also, more likely to be important, and not a probe. */ | |
243 | set_bit(IPS_ASSURED_BIT, &ct->status); | |
a71996fc | 244 | nf_conntrack_event_cache(IPCT_STATUS, ct); |
f09943fe PM |
245 | } else |
246 | nf_ct_refresh_acct(ct, ctinfo, skb, | |
247 | ct->proto.gre.timeout); | |
248 | ||
249 | return NF_ACCEPT; | |
250 | } | |
251 | ||
252 | /* Called when a new connection for this protocol found. */ | |
09f263cd JE |
253 | static bool gre_new(struct nf_conn *ct, const struct sk_buff *skb, |
254 | unsigned int dataoff) | |
f09943fe | 255 | { |
0d53778e | 256 | pr_debug(": "); |
3c9fba65 | 257 | nf_ct_dump_tuple(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple); |
f09943fe PM |
258 | |
259 | /* initialize to sane value. Ideally a conntrack helper | |
260 | * (e.g. in case of pptp) is increasing them */ | |
261 | ct->proto.gre.stream_timeout = GRE_STREAM_TIMEOUT; | |
262 | ct->proto.gre.timeout = GRE_TIMEOUT; | |
263 | ||
09f263cd | 264 | return true; |
f09943fe PM |
265 | } |
266 | ||
267 | /* Called when a conntrack entry has already been removed from the hashes | |
268 | * and is about to be deleted from memory */ | |
269 | static void gre_destroy(struct nf_conn *ct) | |
270 | { | |
271 | struct nf_conn *master = ct->master; | |
0d53778e | 272 | pr_debug(" entering\n"); |
f09943fe PM |
273 | |
274 | if (!master) | |
0d53778e | 275 | pr_debug("no master !?!\n"); |
f09943fe PM |
276 | else |
277 | nf_ct_gre_keymap_destroy(master); | |
278 | } | |
279 | ||
280 | /* protocol helper struct */ | |
61075af5 | 281 | static struct nf_conntrack_l4proto nf_conntrack_l4proto_gre4 __read_mostly = { |
f09943fe PM |
282 | .l3proto = AF_INET, |
283 | .l4proto = IPPROTO_GRE, | |
284 | .name = "gre", | |
285 | .pkt_to_tuple = gre_pkt_to_tuple, | |
286 | .invert_tuple = gre_invert_tuple, | |
287 | .print_tuple = gre_print_tuple, | |
288 | .print_conntrack = gre_print_conntrack, | |
289 | .packet = gre_packet, | |
290 | .new = gre_new, | |
291 | .destroy = gre_destroy, | |
292 | .me = THIS_MODULE, | |
e281db5c | 293 | #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE) |
fdf70832 | 294 | .tuple_to_nlattr = nf_ct_port_tuple_to_nlattr, |
a400c30e | 295 | .nlattr_tuple_size = nf_ct_port_nlattr_tuple_size, |
fdf70832 | 296 | .nlattr_to_tuple = nf_ct_port_nlattr_to_tuple, |
f73e924c | 297 | .nla_policy = nf_ct_port_nla_policy, |
f09943fe PM |
298 | #endif |
299 | }; | |
300 | ||
3bb0d1c0 AD |
301 | static int proto_gre_net_init(struct net *net) |
302 | { | |
303 | struct netns_proto_gre *net_gre; | |
304 | int rv; | |
305 | ||
306 | net_gre = kmalloc(sizeof(struct netns_proto_gre), GFP_KERNEL); | |
307 | if (!net_gre) | |
308 | return -ENOMEM; | |
309 | rwlock_init(&net_gre->keymap_lock); | |
310 | INIT_LIST_HEAD(&net_gre->keymap_list); | |
311 | ||
312 | rv = net_assign_generic(net, proto_gre_net_id, net_gre); | |
313 | if (rv < 0) | |
314 | kfree(net_gre); | |
315 | return rv; | |
316 | } | |
317 | ||
318 | static void proto_gre_net_exit(struct net *net) | |
319 | { | |
320 | struct netns_proto_gre *net_gre = net_generic(net, proto_gre_net_id); | |
321 | ||
322 | nf_ct_gre_keymap_flush(net); | |
323 | kfree(net_gre); | |
324 | } | |
325 | ||
326 | static struct pernet_operations proto_gre_net_ops = { | |
327 | .init = proto_gre_net_init, | |
328 | .exit = proto_gre_net_exit, | |
329 | }; | |
330 | ||
f09943fe PM |
331 | static int __init nf_ct_proto_gre_init(void) |
332 | { | |
3bb0d1c0 AD |
333 | int rv; |
334 | ||
335 | rv = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_gre4); | |
336 | if (rv < 0) | |
337 | return rv; | |
61e57448 | 338 | rv = register_pernet_gen_subsys(&proto_gre_net_id, &proto_gre_net_ops); |
3bb0d1c0 AD |
339 | if (rv < 0) |
340 | nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_gre4); | |
341 | return rv; | |
f09943fe PM |
342 | } |
343 | ||
56bc0f96 | 344 | static void __exit nf_ct_proto_gre_fini(void) |
f09943fe PM |
345 | { |
346 | nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_gre4); | |
61e57448 | 347 | unregister_pernet_gen_subsys(proto_gre_net_id, &proto_gre_net_ops); |
f09943fe PM |
348 | } |
349 | ||
350 | module_init(nf_ct_proto_gre_init); | |
351 | module_exit(nf_ct_proto_gre_fini); | |
352 | ||
353 | MODULE_LICENSE("GPL"); |