Commit | Line | Data |
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457c8996 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
f09943fe | 2 | /* |
f09943fe PM |
3 | * Connection tracking protocol helper module for GRE. |
4 | * | |
5 | * GRE is a generic encapsulation protocol, which is generally not very | |
6 | * suited for NAT, as it has no protocol-specific part as port numbers. | |
7 | * | |
8 | * It has an optional key field, which may help us distinguishing two | |
9 | * connections between the same two hosts. | |
10 | * | |
11 | * GRE is defined in RFC 1701 and RFC 1702, as well as RFC 2784 | |
12 | * | |
13 | * PPTP is built on top of a modified version of GRE, and has a mandatory | |
14 | * field called "CallID", which serves us for the same purpose as the key | |
15 | * field in plain GRE. | |
16 | * | |
17 | * Documentation about PPTP can be found in RFC 2637 | |
18 | * | |
19 | * (C) 2000-2005 by Harald Welte <laforge@gnumonks.org> | |
20 | * | |
21 | * Development of this code funded by Astaro AG (http://www.astaro.com/) | |
22 | * | |
f229f6ce | 23 | * (C) 2006-2012 Patrick McHardy <kaber@trash.net> |
f09943fe PM |
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> |
5a0e3ad6 | 34 | #include <linux/slab.h> |
3bb0d1c0 AD |
35 | #include <net/dst.h> |
36 | #include <net/net_namespace.h> | |
37 | #include <net/netns/generic.h> | |
f09943fe PM |
38 | #include <net/netfilter/nf_conntrack_l4proto.h> |
39 | #include <net/netfilter/nf_conntrack_helper.h> | |
40 | #include <net/netfilter/nf_conntrack_core.h> | |
c779e849 | 41 | #include <net/netfilter/nf_conntrack_timeout.h> |
f09943fe PM |
42 | #include <linux/netfilter/nf_conntrack_proto_gre.h> |
43 | #include <linux/netfilter/nf_conntrack_pptp.h> | |
44 | ||
2c9e8637 | 45 | static const unsigned int gre_timeouts[GRE_CT_MAX] = { |
b888341c PNA |
46 | [GRE_CT_UNREPLIED] = 30*HZ, |
47 | [GRE_CT_REPLIED] = 180*HZ, | |
48 | }; | |
f09943fe | 49 | |
202e651c FW |
50 | /* used when expectation is added */ |
51 | static DEFINE_SPINLOCK(keymap_lock); | |
f09943fe | 52 | |
22fc4c4c | 53 | static inline struct nf_gre_net *gre_pernet(struct net *net) |
4f71d80f | 54 | { |
22fc4c4c | 55 | return &net->ct.nf_ct_proto.gre; |
4f71d80f G |
56 | } |
57 | ||
f09943fe PM |
58 | static inline int gre_key_cmpfn(const struct nf_ct_gre_keymap *km, |
59 | const struct nf_conntrack_tuple *t) | |
60 | { | |
61 | return km->tuple.src.l3num == t->src.l3num && | |
62 | !memcmp(&km->tuple.src.u3, &t->src.u3, sizeof(t->src.u3)) && | |
63 | !memcmp(&km->tuple.dst.u3, &t->dst.u3, sizeof(t->dst.u3)) && | |
64 | km->tuple.dst.protonum == t->dst.protonum && | |
65 | km->tuple.dst.u.all == t->dst.u.all; | |
66 | } | |
67 | ||
68 | /* look up the source key for a given tuple */ | |
3bb0d1c0 | 69 | static __be16 gre_keymap_lookup(struct net *net, struct nf_conntrack_tuple *t) |
f09943fe | 70 | { |
22fc4c4c | 71 | struct nf_gre_net *net_gre = gre_pernet(net); |
f09943fe PM |
72 | struct nf_ct_gre_keymap *km; |
73 | __be16 key = 0; | |
74 | ||
202e651c | 75 | list_for_each_entry_rcu(km, &net_gre->keymap_list, list) { |
f09943fe PM |
76 | if (gre_key_cmpfn(km, t)) { |
77 | key = km->tuple.src.u.gre.key; | |
78 | break; | |
79 | } | |
80 | } | |
f09943fe | 81 | |
0d53778e | 82 | pr_debug("lookup src key 0x%x for ", key); |
3c9fba65 | 83 | nf_ct_dump_tuple(t); |
f09943fe PM |
84 | |
85 | return key; | |
86 | } | |
87 | ||
88 | /* add a single keymap entry, associate with specified master ct */ | |
89 | int nf_ct_gre_keymap_add(struct nf_conn *ct, enum ip_conntrack_dir dir, | |
90 | struct nf_conntrack_tuple *t) | |
91 | { | |
3bb0d1c0 | 92 | struct net *net = nf_ct_net(ct); |
22fc4c4c | 93 | struct nf_gre_net *net_gre = gre_pernet(net); |
1afc5679 | 94 | struct nf_ct_pptp_master *ct_pptp_info = nfct_help_data(ct); |
f09943fe PM |
95 | struct nf_ct_gre_keymap **kmp, *km; |
96 | ||
1afc5679 | 97 | kmp = &ct_pptp_info->keymap[dir]; |
f09943fe PM |
98 | if (*kmp) { |
99 | /* check whether it's a retransmission */ | |
202e651c FW |
100 | list_for_each_entry_rcu(km, &net_gre->keymap_list, list) { |
101 | if (gre_key_cmpfn(km, t) && km == *kmp) | |
f09943fe PM |
102 | return 0; |
103 | } | |
0d53778e PM |
104 | pr_debug("trying to override keymap_%s for ct %p\n", |
105 | dir == IP_CT_DIR_REPLY ? "reply" : "orig", ct); | |
f09943fe PM |
106 | return -EEXIST; |
107 | } | |
108 | ||
109 | km = kmalloc(sizeof(*km), GFP_ATOMIC); | |
110 | if (!km) | |
111 | return -ENOMEM; | |
112 | memcpy(&km->tuple, t, sizeof(*t)); | |
113 | *kmp = km; | |
114 | ||
0d53778e | 115 | pr_debug("adding new entry %p: ", km); |
3c9fba65 | 116 | nf_ct_dump_tuple(&km->tuple); |
f09943fe | 117 | |
202e651c | 118 | spin_lock_bh(&keymap_lock); |
3bb0d1c0 | 119 | list_add_tail(&km->list, &net_gre->keymap_list); |
202e651c | 120 | spin_unlock_bh(&keymap_lock); |
f09943fe PM |
121 | |
122 | return 0; | |
123 | } | |
124 | EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_add); | |
125 | ||
126 | /* destroy the keymap entries associated with specified master ct */ | |
127 | void nf_ct_gre_keymap_destroy(struct nf_conn *ct) | |
128 | { | |
1afc5679 | 129 | struct nf_ct_pptp_master *ct_pptp_info = nfct_help_data(ct); |
f09943fe PM |
130 | enum ip_conntrack_dir dir; |
131 | ||
0d53778e | 132 | pr_debug("entering for ct %p\n", ct); |
f09943fe | 133 | |
202e651c | 134 | spin_lock_bh(&keymap_lock); |
f09943fe | 135 | for (dir = IP_CT_DIR_ORIGINAL; dir < IP_CT_DIR_MAX; dir++) { |
1afc5679 | 136 | if (ct_pptp_info->keymap[dir]) { |
0d53778e | 137 | pr_debug("removing %p from list\n", |
1afc5679 | 138 | ct_pptp_info->keymap[dir]); |
202e651c FW |
139 | list_del_rcu(&ct_pptp_info->keymap[dir]->list); |
140 | kfree_rcu(ct_pptp_info->keymap[dir], rcu); | |
1afc5679 | 141 | ct_pptp_info->keymap[dir] = NULL; |
f09943fe PM |
142 | } |
143 | } | |
202e651c | 144 | spin_unlock_bh(&keymap_lock); |
f09943fe PM |
145 | } |
146 | EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_destroy); | |
147 | ||
148 | /* PUBLIC CONNTRACK PROTO HELPER FUNCTIONS */ | |
149 | ||
f09943fe | 150 | /* gre hdr info to tuple */ |
df5e1629 FW |
151 | bool gre_pkt_to_tuple(const struct sk_buff *skb, unsigned int dataoff, |
152 | struct net *net, struct nf_conntrack_tuple *tuple) | |
f09943fe | 153 | { |
c579a9e7 GF |
154 | const struct pptp_gre_header *pgrehdr; |
155 | struct pptp_gre_header _pgrehdr; | |
f09943fe | 156 | __be16 srckey; |
c579a9e7 GF |
157 | const struct gre_base_hdr *grehdr; |
158 | struct gre_base_hdr _grehdr; | |
f09943fe PM |
159 | |
160 | /* first only delinearize old RFC1701 GRE header */ | |
161 | grehdr = skb_header_pointer(skb, dataoff, sizeof(_grehdr), &_grehdr); | |
c579a9e7 | 162 | if (!grehdr || (grehdr->flags & GRE_VERSION) != GRE_VERSION_1) { |
f09943fe PM |
163 | /* try to behave like "nf_conntrack_proto_generic" */ |
164 | tuple->src.u.all = 0; | |
165 | tuple->dst.u.all = 0; | |
09f263cd | 166 | return true; |
f09943fe PM |
167 | } |
168 | ||
169 | /* PPTP header is variable length, only need up to the call_id field */ | |
170 | pgrehdr = skb_header_pointer(skb, dataoff, 8, &_pgrehdr); | |
171 | if (!pgrehdr) | |
09f263cd | 172 | return true; |
f09943fe | 173 | |
ecc6569f | 174 | if (grehdr->protocol != GRE_PROTO_PPP) { |
c579a9e7 | 175 | pr_debug("Unsupported GRE proto(0x%x)\n", ntohs(grehdr->protocol)); |
09f263cd | 176 | return false; |
f09943fe PM |
177 | } |
178 | ||
179 | tuple->dst.u.gre.key = pgrehdr->call_id; | |
3bb0d1c0 | 180 | srckey = gre_keymap_lookup(net, tuple); |
f09943fe PM |
181 | tuple->src.u.gre.key = srckey; |
182 | ||
09f263cd | 183 | return true; |
f09943fe PM |
184 | } |
185 | ||
ea48cc83 | 186 | #ifdef CONFIG_NF_CONNTRACK_PROCFS |
f09943fe | 187 | /* print private data for conntrack */ |
37246a58 | 188 | static void gre_print_conntrack(struct seq_file *s, struct nf_conn *ct) |
f09943fe | 189 | { |
37246a58 SRRH |
190 | seq_printf(s, "timeout=%u, stream_timeout=%u ", |
191 | (ct->proto.gre.timeout / HZ), | |
192 | (ct->proto.gre.stream_timeout / HZ)); | |
f09943fe | 193 | } |
ea48cc83 | 194 | #endif |
f09943fe | 195 | |
2c8503f5 PNA |
196 | static unsigned int *gre_get_timeouts(struct net *net) |
197 | { | |
22fc4c4c | 198 | return gre_pernet(net)->timeouts; |
2c8503f5 PNA |
199 | } |
200 | ||
f09943fe | 201 | /* Returns verdict for packet, and may modify conntrack */ |
44fb87f6 FW |
202 | int nf_conntrack_gre_packet(struct nf_conn *ct, |
203 | struct sk_buff *skb, | |
204 | unsigned int dataoff, | |
205 | enum ip_conntrack_info ctinfo, | |
206 | const struct nf_hook_state *state) | |
f09943fe | 207 | { |
8a9dc07b FW |
208 | unsigned long status; |
209 | ||
9976fc6e FW |
210 | if (!nf_ct_is_confirmed(ct)) { |
211 | unsigned int *timeouts = nf_ct_timeout_lookup(ct); | |
212 | ||
213 | if (!timeouts) | |
214 | timeouts = gre_get_timeouts(nf_ct_net(ct)); | |
215 | ||
216 | /* initialize to sane value. Ideally a conntrack helper | |
217 | * (e.g. in case of pptp) is increasing them */ | |
218 | ct->proto.gre.stream_timeout = timeouts[GRE_CT_REPLIED]; | |
219 | ct->proto.gre.timeout = timeouts[GRE_CT_UNREPLIED]; | |
220 | } | |
221 | ||
8a9dc07b | 222 | status = READ_ONCE(ct->status); |
f09943fe PM |
223 | /* If we've seen traffic both ways, this is a GRE connection. |
224 | * Extend timeout. */ | |
8a9dc07b | 225 | if (status & IPS_SEEN_REPLY) { |
f09943fe PM |
226 | nf_ct_refresh_acct(ct, ctinfo, skb, |
227 | ct->proto.gre.stream_timeout); | |
8a9dc07b FW |
228 | |
229 | /* never set ASSURED for IPS_NAT_CLASH, they time out soon */ | |
230 | if (unlikely((status & IPS_NAT_CLASH))) | |
231 | return NF_ACCEPT; | |
232 | ||
f09943fe | 233 | /* Also, more likely to be important, and not a probe. */ |
98d9ae84 FW |
234 | if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status)) |
235 | nf_conntrack_event_cache(IPCT_ASSURED, ct); | |
f09943fe PM |
236 | } else |
237 | nf_ct_refresh_acct(ct, ctinfo, skb, | |
238 | ct->proto.gre.timeout); | |
239 | ||
240 | return NF_ACCEPT; | |
241 | } | |
242 | ||
a874752a | 243 | #ifdef CONFIG_NF_CONNTRACK_TIMEOUT |
50978462 PNA |
244 | |
245 | #include <linux/netfilter/nfnetlink.h> | |
246 | #include <linux/netfilter/nfnetlink_cttimeout.h> | |
247 | ||
8264deb8 G |
248 | static int gre_timeout_nlattr_to_obj(struct nlattr *tb[], |
249 | struct net *net, void *data) | |
50978462 PNA |
250 | { |
251 | unsigned int *timeouts = data; | |
22fc4c4c | 252 | struct nf_gre_net *net_gre = gre_pernet(net); |
50978462 | 253 | |
c779e849 FW |
254 | if (!timeouts) |
255 | timeouts = gre_get_timeouts(net); | |
50978462 | 256 | /* set default timeouts for GRE. */ |
22fc4c4c FW |
257 | timeouts[GRE_CT_UNREPLIED] = net_gre->timeouts[GRE_CT_UNREPLIED]; |
258 | timeouts[GRE_CT_REPLIED] = net_gre->timeouts[GRE_CT_REPLIED]; | |
50978462 PNA |
259 | |
260 | if (tb[CTA_TIMEOUT_GRE_UNREPLIED]) { | |
261 | timeouts[GRE_CT_UNREPLIED] = | |
262 | ntohl(nla_get_be32(tb[CTA_TIMEOUT_GRE_UNREPLIED])) * HZ; | |
263 | } | |
264 | if (tb[CTA_TIMEOUT_GRE_REPLIED]) { | |
265 | timeouts[GRE_CT_REPLIED] = | |
266 | ntohl(nla_get_be32(tb[CTA_TIMEOUT_GRE_REPLIED])) * HZ; | |
267 | } | |
268 | return 0; | |
269 | } | |
270 | ||
271 | static int | |
272 | gre_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data) | |
273 | { | |
274 | const unsigned int *timeouts = data; | |
275 | ||
242ddfc0 DM |
276 | if (nla_put_be32(skb, CTA_TIMEOUT_GRE_UNREPLIED, |
277 | htonl(timeouts[GRE_CT_UNREPLIED] / HZ)) || | |
278 | nla_put_be32(skb, CTA_TIMEOUT_GRE_REPLIED, | |
279 | htonl(timeouts[GRE_CT_REPLIED] / HZ))) | |
280 | goto nla_put_failure; | |
50978462 PNA |
281 | return 0; |
282 | ||
283 | nla_put_failure: | |
284 | return -ENOSPC; | |
285 | } | |
286 | ||
287 | static const struct nla_policy | |
288 | gre_timeout_nla_policy[CTA_TIMEOUT_GRE_MAX+1] = { | |
289 | [CTA_TIMEOUT_GRE_UNREPLIED] = { .type = NLA_U32 }, | |
290 | [CTA_TIMEOUT_GRE_REPLIED] = { .type = NLA_U32 }, | |
291 | }; | |
a874752a | 292 | #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */ |
50978462 | 293 | |
2a389de8 | 294 | void nf_conntrack_gre_init_net(struct net *net) |
4f71d80f | 295 | { |
22fc4c4c | 296 | struct nf_gre_net *net_gre = gre_pernet(net); |
4f71d80f G |
297 | int i; |
298 | ||
4f71d80f G |
299 | INIT_LIST_HEAD(&net_gre->keymap_list); |
300 | for (i = 0; i < GRE_CT_MAX; i++) | |
22fc4c4c | 301 | net_gre->timeouts[i] = gre_timeouts[i]; |
4f71d80f G |
302 | } |
303 | ||
f09943fe | 304 | /* protocol helper struct */ |
22fc4c4c | 305 | const struct nf_conntrack_l4proto nf_conntrack_l4proto_gre = { |
f09943fe | 306 | .l4proto = IPPROTO_GRE, |
d671fd82 | 307 | .allow_clash = true, |
ea48cc83 | 308 | #ifdef CONFIG_NF_CONNTRACK_PROCFS |
f09943fe | 309 | .print_conntrack = gre_print_conntrack, |
ea48cc83 | 310 | #endif |
c0cd1156 | 311 | #if IS_ENABLED(CONFIG_NF_CT_NETLINK) |
fdf70832 | 312 | .tuple_to_nlattr = nf_ct_port_tuple_to_nlattr, |
a400c30e | 313 | .nlattr_tuple_size = nf_ct_port_nlattr_tuple_size, |
fdf70832 | 314 | .nlattr_to_tuple = nf_ct_port_nlattr_to_tuple, |
f73e924c | 315 | .nla_policy = nf_ct_port_nla_policy, |
f09943fe | 316 | #endif |
a874752a | 317 | #ifdef CONFIG_NF_CONNTRACK_TIMEOUT |
50978462 PNA |
318 | .ctnl_timeout = { |
319 | .nlattr_to_obj = gre_timeout_nlattr_to_obj, | |
320 | .obj_to_nlattr = gre_timeout_obj_to_nlattr, | |
321 | .nlattr_max = CTA_TIMEOUT_GRE_MAX, | |
322 | .obj_size = sizeof(unsigned int) * GRE_CT_MAX, | |
323 | .nla_policy = gre_timeout_nla_policy, | |
324 | }, | |
a874752a | 325 | #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */ |
f09943fe | 326 | }; |