1 // SPDX-License-Identifier: GPL-2.0-only
3 * Connection tracking protocol helper module for GRE.
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.
8 * It has an optional key field, which may help us distinguishing two
9 * connections between the same two hosts.
11 * GRE is defined in RFC 1701 and RFC 1702, as well as RFC 2784
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
17 * Documentation about PPTP can be found in RFC 2637
19 * (C) 2000-2005 by Harald Welte <laforge@gnumonks.org>
21 * Development of this code funded by Astaro AG (http://www.astaro.com/)
23 * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
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 <net/netfilter/nf_conntrack_timeout.h>
42 #include <linux/netfilter/nf_conntrack_proto_gre.h>
43 #include <linux/netfilter/nf_conntrack_pptp.h>
45 static const unsigned int gre_timeouts
[GRE_CT_MAX
] = {
46 [GRE_CT_UNREPLIED
] = 30*HZ
,
47 [GRE_CT_REPLIED
] = 180*HZ
,
50 /* used when expectation is added */
51 static DEFINE_SPINLOCK(keymap_lock
);
53 static inline struct nf_gre_net
*gre_pernet(struct net
*net
)
55 return &net
->ct
.nf_ct_proto
.gre
;
58 void nf_ct_gre_keymap_flush(struct net
*net
)
60 struct nf_gre_net
*net_gre
= gre_pernet(net
);
61 struct nf_ct_gre_keymap
*km
, *tmp
;
63 spin_lock_bh(&keymap_lock
);
64 list_for_each_entry_safe(km
, tmp
, &net_gre
->keymap_list
, list
) {
65 list_del_rcu(&km
->list
);
68 spin_unlock_bh(&keymap_lock
);
71 static inline int gre_key_cmpfn(const struct nf_ct_gre_keymap
*km
,
72 const struct nf_conntrack_tuple
*t
)
74 return km
->tuple
.src
.l3num
== t
->src
.l3num
&&
75 !memcmp(&km
->tuple
.src
.u3
, &t
->src
.u3
, sizeof(t
->src
.u3
)) &&
76 !memcmp(&km
->tuple
.dst
.u3
, &t
->dst
.u3
, sizeof(t
->dst
.u3
)) &&
77 km
->tuple
.dst
.protonum
== t
->dst
.protonum
&&
78 km
->tuple
.dst
.u
.all
== t
->dst
.u
.all
;
81 /* look up the source key for a given tuple */
82 static __be16
gre_keymap_lookup(struct net
*net
, struct nf_conntrack_tuple
*t
)
84 struct nf_gre_net
*net_gre
= gre_pernet(net
);
85 struct nf_ct_gre_keymap
*km
;
88 list_for_each_entry_rcu(km
, &net_gre
->keymap_list
, list
) {
89 if (gre_key_cmpfn(km
, t
)) {
90 key
= km
->tuple
.src
.u
.gre
.key
;
95 pr_debug("lookup src key 0x%x for ", key
);
101 /* add a single keymap entry, associate with specified master ct */
102 int nf_ct_gre_keymap_add(struct nf_conn
*ct
, enum ip_conntrack_dir dir
,
103 struct nf_conntrack_tuple
*t
)
105 struct net
*net
= nf_ct_net(ct
);
106 struct nf_gre_net
*net_gre
= gre_pernet(net
);
107 struct nf_ct_pptp_master
*ct_pptp_info
= nfct_help_data(ct
);
108 struct nf_ct_gre_keymap
**kmp
, *km
;
110 kmp
= &ct_pptp_info
->keymap
[dir
];
112 /* check whether it's a retransmission */
113 list_for_each_entry_rcu(km
, &net_gre
->keymap_list
, list
) {
114 if (gre_key_cmpfn(km
, t
) && km
== *kmp
)
117 pr_debug("trying to override keymap_%s for ct %p\n",
118 dir
== IP_CT_DIR_REPLY
? "reply" : "orig", ct
);
122 km
= kmalloc(sizeof(*km
), GFP_ATOMIC
);
125 memcpy(&km
->tuple
, t
, sizeof(*t
));
128 pr_debug("adding new entry %p: ", km
);
129 nf_ct_dump_tuple(&km
->tuple
);
131 spin_lock_bh(&keymap_lock
);
132 list_add_tail(&km
->list
, &net_gre
->keymap_list
);
133 spin_unlock_bh(&keymap_lock
);
137 EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_add
);
139 /* destroy the keymap entries associated with specified master ct */
140 void nf_ct_gre_keymap_destroy(struct nf_conn
*ct
)
142 struct nf_ct_pptp_master
*ct_pptp_info
= nfct_help_data(ct
);
143 enum ip_conntrack_dir dir
;
145 pr_debug("entering for ct %p\n", ct
);
147 spin_lock_bh(&keymap_lock
);
148 for (dir
= IP_CT_DIR_ORIGINAL
; dir
< IP_CT_DIR_MAX
; dir
++) {
149 if (ct_pptp_info
->keymap
[dir
]) {
150 pr_debug("removing %p from list\n",
151 ct_pptp_info
->keymap
[dir
]);
152 list_del_rcu(&ct_pptp_info
->keymap
[dir
]->list
);
153 kfree_rcu(ct_pptp_info
->keymap
[dir
], rcu
);
154 ct_pptp_info
->keymap
[dir
] = NULL
;
157 spin_unlock_bh(&keymap_lock
);
159 EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_destroy
);
161 /* PUBLIC CONNTRACK PROTO HELPER FUNCTIONS */
163 /* gre hdr info to tuple */
164 bool gre_pkt_to_tuple(const struct sk_buff
*skb
, unsigned int dataoff
,
165 struct net
*net
, struct nf_conntrack_tuple
*tuple
)
167 const struct pptp_gre_header
*pgrehdr
;
168 struct pptp_gre_header _pgrehdr
;
170 const struct gre_base_hdr
*grehdr
;
171 struct gre_base_hdr _grehdr
;
173 /* first only delinearize old RFC1701 GRE header */
174 grehdr
= skb_header_pointer(skb
, dataoff
, sizeof(_grehdr
), &_grehdr
);
175 if (!grehdr
|| (grehdr
->flags
& GRE_VERSION
) != GRE_VERSION_1
) {
176 /* try to behave like "nf_conntrack_proto_generic" */
177 tuple
->src
.u
.all
= 0;
178 tuple
->dst
.u
.all
= 0;
182 /* PPTP header is variable length, only need up to the call_id field */
183 pgrehdr
= skb_header_pointer(skb
, dataoff
, 8, &_pgrehdr
);
187 if (grehdr
->protocol
!= GRE_PROTO_PPP
) {
188 pr_debug("Unsupported GRE proto(0x%x)\n", ntohs(grehdr
->protocol
));
192 tuple
->dst
.u
.gre
.key
= pgrehdr
->call_id
;
193 srckey
= gre_keymap_lookup(net
, tuple
);
194 tuple
->src
.u
.gre
.key
= srckey
;
199 #ifdef CONFIG_NF_CONNTRACK_PROCFS
200 /* print private data for conntrack */
201 static void gre_print_conntrack(struct seq_file
*s
, struct nf_conn
*ct
)
203 seq_printf(s
, "timeout=%u, stream_timeout=%u ",
204 (ct
->proto
.gre
.timeout
/ HZ
),
205 (ct
->proto
.gre
.stream_timeout
/ HZ
));
209 static unsigned int *gre_get_timeouts(struct net
*net
)
211 return gre_pernet(net
)->timeouts
;
214 /* Returns verdict for packet, and may modify conntrack */
215 int nf_conntrack_gre_packet(struct nf_conn
*ct
,
217 unsigned int dataoff
,
218 enum ip_conntrack_info ctinfo
,
219 const struct nf_hook_state
*state
)
221 if (state
->pf
!= NFPROTO_IPV4
)
224 if (!nf_ct_is_confirmed(ct
)) {
225 unsigned int *timeouts
= nf_ct_timeout_lookup(ct
);
228 timeouts
= gre_get_timeouts(nf_ct_net(ct
));
230 /* initialize to sane value. Ideally a conntrack helper
231 * (e.g. in case of pptp) is increasing them */
232 ct
->proto
.gre
.stream_timeout
= timeouts
[GRE_CT_REPLIED
];
233 ct
->proto
.gre
.timeout
= timeouts
[GRE_CT_UNREPLIED
];
236 /* If we've seen traffic both ways, this is a GRE connection.
238 if (ct
->status
& IPS_SEEN_REPLY
) {
239 nf_ct_refresh_acct(ct
, ctinfo
, skb
,
240 ct
->proto
.gre
.stream_timeout
);
241 /* Also, more likely to be important, and not a probe. */
242 if (!test_and_set_bit(IPS_ASSURED_BIT
, &ct
->status
))
243 nf_conntrack_event_cache(IPCT_ASSURED
, ct
);
245 nf_ct_refresh_acct(ct
, ctinfo
, skb
,
246 ct
->proto
.gre
.timeout
);
251 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
253 #include <linux/netfilter/nfnetlink.h>
254 #include <linux/netfilter/nfnetlink_cttimeout.h>
256 static int gre_timeout_nlattr_to_obj(struct nlattr
*tb
[],
257 struct net
*net
, void *data
)
259 unsigned int *timeouts
= data
;
260 struct nf_gre_net
*net_gre
= gre_pernet(net
);
263 timeouts
= gre_get_timeouts(net
);
264 /* set default timeouts for GRE. */
265 timeouts
[GRE_CT_UNREPLIED
] = net_gre
->timeouts
[GRE_CT_UNREPLIED
];
266 timeouts
[GRE_CT_REPLIED
] = net_gre
->timeouts
[GRE_CT_REPLIED
];
268 if (tb
[CTA_TIMEOUT_GRE_UNREPLIED
]) {
269 timeouts
[GRE_CT_UNREPLIED
] =
270 ntohl(nla_get_be32(tb
[CTA_TIMEOUT_GRE_UNREPLIED
])) * HZ
;
272 if (tb
[CTA_TIMEOUT_GRE_REPLIED
]) {
273 timeouts
[GRE_CT_REPLIED
] =
274 ntohl(nla_get_be32(tb
[CTA_TIMEOUT_GRE_REPLIED
])) * HZ
;
280 gre_timeout_obj_to_nlattr(struct sk_buff
*skb
, const void *data
)
282 const unsigned int *timeouts
= data
;
284 if (nla_put_be32(skb
, CTA_TIMEOUT_GRE_UNREPLIED
,
285 htonl(timeouts
[GRE_CT_UNREPLIED
] / HZ
)) ||
286 nla_put_be32(skb
, CTA_TIMEOUT_GRE_REPLIED
,
287 htonl(timeouts
[GRE_CT_REPLIED
] / HZ
)))
288 goto nla_put_failure
;
295 static const struct nla_policy
296 gre_timeout_nla_policy
[CTA_TIMEOUT_GRE_MAX
+1] = {
297 [CTA_TIMEOUT_GRE_UNREPLIED
] = { .type
= NLA_U32
},
298 [CTA_TIMEOUT_GRE_REPLIED
] = { .type
= NLA_U32
},
300 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
302 void nf_conntrack_gre_init_net(struct net
*net
)
304 struct nf_gre_net
*net_gre
= gre_pernet(net
);
307 INIT_LIST_HEAD(&net_gre
->keymap_list
);
308 for (i
= 0; i
< GRE_CT_MAX
; i
++)
309 net_gre
->timeouts
[i
] = gre_timeouts
[i
];
312 /* protocol helper struct */
313 const struct nf_conntrack_l4proto nf_conntrack_l4proto_gre
= {
314 .l4proto
= IPPROTO_GRE
,
315 #ifdef CONFIG_NF_CONNTRACK_PROCFS
316 .print_conntrack
= gre_print_conntrack
,
318 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
319 .tuple_to_nlattr
= nf_ct_port_tuple_to_nlattr
,
320 .nlattr_tuple_size
= nf_ct_port_nlattr_tuple_size
,
321 .nlattr_to_tuple
= nf_ct_port_nlattr_to_tuple
,
322 .nla_policy
= nf_ct_port_nla_policy
,
324 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
326 .nlattr_to_obj
= gre_timeout_nlattr_to_obj
,
327 .obj_to_nlattr
= gre_timeout_obj_to_nlattr
,
328 .nlattr_max
= CTA_TIMEOUT_GRE_MAX
,
329 .obj_size
= sizeof(unsigned int) * GRE_CT_MAX
,
330 .nla_policy
= gre_timeout_nla_policy
,
332 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */