blob: 5cb0b5995bc806a2b9e663d79cae17152de8c55c [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * xfrm4_input.c
3 *
4 * Changes:
5 * YOSHIFUJI Hideaki @USAGI
6 * Split up af-specific portion
7 * Derek Atkins <derek@ihtfp.com>
8 * Add Encapsulation support
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09009 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070010 */
11
12#include <linux/module.h>
13#include <linux/string.h>
Patrick McHardyb05e1062006-01-06 23:03:34 -080014#include <linux/netfilter.h>
15#include <linux/netfilter_ipv4.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070016#include <net/ip.h>
17#include <net/xfrm.h>
18
Patrick McHardyb05e1062006-01-06 23:03:34 -080019#ifdef CONFIG_NETFILTER
20static inline int xfrm4_rcv_encap_finish(struct sk_buff *skb)
21{
Patrick McHardyb05e1062006-01-06 23:03:34 -080022 if (skb->dst == NULL) {
Arnaldo Carvalho de Meloeddc9ec2007-04-20 22:47:35 -070023 const struct iphdr *iph = ip_hdr(skb);
24
Patrick McHardyb05e1062006-01-06 23:03:34 -080025 if (ip_route_input(skb, iph->daddr, iph->saddr, iph->tos,
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +090026 skb->dev))
Patrick McHardyb05e1062006-01-06 23:03:34 -080027 goto drop;
28 }
29 return dst_input(skb);
30drop:
31 kfree_skb(skb);
32 return NET_RX_DROP;
33}
34#endif
35
Herbert Xuc4541b42007-10-17 21:28:53 -070036int xfrm4_rcv_encap(struct sk_buff *skb, int nexthdr, __be32 spi,
37 int encap_type)
Linus Torvalds1da177e2005-04-16 15:20:36 -070038{
Herbert Xuc4541b42007-10-17 21:28:53 -070039 int err;
40 __be32 seq;
Herbert Xudbe5b4a2006-04-01 00:54:16 -080041 struct xfrm_state *xfrm_vec[XFRM_MAX_DEPTH];
Linus Torvalds1da177e2005-04-16 15:20:36 -070042 struct xfrm_state *x;
43 int xfrm_nr = 0;
44 int decaps = 0;
Herbert Xu631a66982007-10-10 15:46:21 -070045 unsigned int nhoff = offsetof(struct iphdr, protocol);
Linus Torvalds1da177e2005-04-16 15:20:36 -070046
Herbert Xuc4541b42007-10-17 21:28:53 -070047 seq = 0;
48 if (!spi && (err = xfrm_parse_spi(skb, nexthdr, &spi, &seq)) != 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -070049 goto drop;
50
51 do {
Arnaldo Carvalho de Meloeddc9ec2007-04-20 22:47:35 -070052 const struct iphdr *iph = ip_hdr(skb);
Linus Torvalds1da177e2005-04-16 15:20:36 -070053
54 if (xfrm_nr == XFRM_MAX_DEPTH)
55 goto drop;
56
Kazunori MIYAZAWAc0d56402007-02-13 12:54:47 -080057 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi,
Herbert Xuc4541b42007-10-17 21:28:53 -070058 nexthdr, AF_INET);
Linus Torvalds1da177e2005-04-16 15:20:36 -070059 if (x == NULL)
60 goto drop;
61
62 spin_lock(&x->lock);
63 if (unlikely(x->km.state != XFRM_STATE_VALID))
64 goto drop_unlock;
65
Herbert Xu8bf4b8a2006-04-04 12:51:05 -070066 if ((x->encap ? x->encap->encap_type : 0) != encap_type)
Herbert Xue6956332006-04-01 00:52:46 -080067 goto drop_unlock;
68
Linus Torvalds1da177e2005-04-16 15:20:36 -070069 if (x->props.replay_window && xfrm_replay_check(x, seq))
70 goto drop_unlock;
71
72 if (xfrm_state_check_expire(x))
73 goto drop_unlock;
74
Herbert Xu631a66982007-10-10 15:46:21 -070075 nexthdr = x->type->input(x, skb);
76 if (nexthdr <= 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -070077 goto drop_unlock;
78
Herbert Xu631a66982007-10-10 15:46:21 -070079 skb_network_header(skb)[nhoff] = nexthdr;
80
Linus Torvalds1da177e2005-04-16 15:20:36 -070081 /* only the first xfrm gets the encap type */
82 encap_type = 0;
83
84 if (x->props.replay_window)
85 xfrm_replay_advance(x, seq);
86
87 x->curlft.bytes += skb->len;
88 x->curlft.packets++;
89
90 spin_unlock(&x->lock);
91
Herbert Xudbe5b4a2006-04-01 00:54:16 -080092 xfrm_vec[xfrm_nr++] = x;
Linus Torvalds1da177e2005-04-16 15:20:36 -070093
Herbert Xub59f45d2006-05-27 23:05:54 -070094 if (x->mode->input(x, skb))
95 goto drop;
Linus Torvalds1da177e2005-04-16 15:20:36 -070096
Masahide NAKAMURA7e49e6d2006-09-22 15:05:15 -070097 if (x->props.mode == XFRM_MODE_TUNNEL) {
Linus Torvalds1da177e2005-04-16 15:20:36 -070098 decaps = 1;
99 break;
100 }
101
Herbert Xuc4541b42007-10-17 21:28:53 -0700102 err = xfrm_parse_spi(skb, nexthdr, &spi, &seq);
Arnaldo Carvalho de Meloeddc9ec2007-04-20 22:47:35 -0700103 if (err < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104 goto drop;
105 } while (!err);
106
107 /* Allocate new secpath or COW existing one. */
108
109 if (!skb->sp || atomic_read(&skb->sp->refcnt) != 1) {
110 struct sec_path *sp;
111 sp = secpath_dup(skb->sp);
112 if (!sp)
113 goto drop;
114 if (skb->sp)
115 secpath_put(skb->sp);
116 skb->sp = sp;
117 }
118 if (xfrm_nr + skb->sp->len > XFRM_MAX_DEPTH)
119 goto drop;
120
Herbert Xudbe5b4a2006-04-01 00:54:16 -0800121 memcpy(skb->sp->xvec + skb->sp->len, xfrm_vec,
122 xfrm_nr * sizeof(xfrm_vec[0]));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123 skb->sp->len += xfrm_nr;
124
Patrick McHardyb05e1062006-01-06 23:03:34 -0800125 nf_reset(skb);
126
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127 if (decaps) {
Kazunori MIYAZAWAf282d452007-05-29 13:03:17 -0700128 dst_release(skb->dst);
129 skb->dst = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130 netif_rx(skb);
131 return 0;
132 } else {
Patrick McHardyb05e1062006-01-06 23:03:34 -0800133#ifdef CONFIG_NETFILTER
Arnaldo Carvalho de Melod56f90a2007-04-10 20:50:43 -0700134 __skb_push(skb, skb->data - skb_network_header(skb));
Arnaldo Carvalho de Meloeddc9ec2007-04-20 22:47:35 -0700135 ip_hdr(skb)->tot_len = htons(skb->len);
136 ip_send_check(ip_hdr(skb));
Patrick McHardyb05e1062006-01-06 23:03:34 -0800137
138 NF_HOOK(PF_INET, NF_IP_PRE_ROUTING, skb, skb->dev, NULL,
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900139 xfrm4_rcv_encap_finish);
Patrick McHardyb05e1062006-01-06 23:03:34 -0800140 return 0;
141#else
Arnaldo Carvalho de Meloeddc9ec2007-04-20 22:47:35 -0700142 return -ip_hdr(skb)->protocol;
Patrick McHardyb05e1062006-01-06 23:03:34 -0800143#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144 }
145
146drop_unlock:
147 spin_unlock(&x->lock);
148 xfrm_state_put(x);
149drop:
150 while (--xfrm_nr >= 0)
Herbert Xudbe5b4a2006-04-01 00:54:16 -0800151 xfrm_state_put(xfrm_vec[xfrm_nr]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152
153 kfree_skb(skb);
154 return 0;
155}
Herbert Xuc4541b42007-10-17 21:28:53 -0700156EXPORT_SYMBOL(xfrm4_rcv_encap);
James Chapman067b2072007-07-05 17:08:05 -0700157
158/* If it's a keepalive packet, then just eat it.
159 * If it's an encapsulated packet, then pass it to the
160 * IPsec xfrm input.
161 * Returns 0 if skb passed to xfrm or was dropped.
162 * Returns >0 if skb should be passed to UDP.
163 * Returns <0 if skb should be resubmitted (-ret is protocol)
164 */
165int xfrm4_udp_encap_rcv(struct sock *sk, struct sk_buff *skb)
166{
167 struct udp_sock *up = udp_sk(sk);
168 struct udphdr *uh;
169 struct iphdr *iph;
170 int iphlen, len;
171 int ret;
172
173 __u8 *udpdata;
174 __be32 *udpdata32;
175 __u16 encap_type = up->encap_type;
176
177 /* if this is not encapsulated socket, then just return now */
178 if (!encap_type)
179 return 1;
180
181 /* If this is a paged skb, make sure we pull up
182 * whatever data we need to look at. */
183 len = skb->len - sizeof(struct udphdr);
184 if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8)))
185 return 1;
186
187 /* Now we can get the pointers */
188 uh = udp_hdr(skb);
189 udpdata = (__u8 *)uh + sizeof(struct udphdr);
190 udpdata32 = (__be32 *)udpdata;
191
192 switch (encap_type) {
193 default:
194 case UDP_ENCAP_ESPINUDP:
195 /* Check if this is a keepalive packet. If so, eat it. */
196 if (len == 1 && udpdata[0] == 0xff) {
197 goto drop;
198 } else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) {
199 /* ESP Packet without Non-ESP header */
200 len = sizeof(struct udphdr);
201 } else
202 /* Must be an IKE packet.. pass it through */
203 return 1;
204 break;
205 case UDP_ENCAP_ESPINUDP_NON_IKE:
206 /* Check if this is a keepalive packet. If so, eat it. */
207 if (len == 1 && udpdata[0] == 0xff) {
208 goto drop;
209 } else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) &&
210 udpdata32[0] == 0 && udpdata32[1] == 0) {
211
212 /* ESP Packet with Non-IKE marker */
213 len = sizeof(struct udphdr) + 2 * sizeof(u32);
214 } else
215 /* Must be an IKE packet.. pass it through */
216 return 1;
217 break;
218 }
219
220 /* At this point we are sure that this is an ESPinUDP packet,
221 * so we need to remove 'len' bytes from the packet (the UDP
222 * header and optional ESP marker bytes) and then modify the
223 * protocol to ESP, and then call into the transform receiver.
224 */
225 if (skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
226 goto drop;
227
228 /* Now we can update and verify the packet length... */
229 iph = ip_hdr(skb);
230 iphlen = iph->ihl << 2;
231 iph->tot_len = htons(ntohs(iph->tot_len) - len);
232 if (skb->len < iphlen + len) {
233 /* packet is too small!?! */
234 goto drop;
235 }
236
237 /* pull the data buffer up to the ESP header and set the
238 * transport header to point to ESP. Keep UDP on the stack
239 * for later.
240 */
241 __skb_pull(skb, len);
242 skb_reset_transport_header(skb);
243
James Chapman067b2072007-07-05 17:08:05 -0700244 /* process ESP */
Herbert Xuc4541b42007-10-17 21:28:53 -0700245 ret = xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, encap_type);
James Chapman067b2072007-07-05 17:08:05 -0700246 return ret;
247
248drop:
249 kfree_skb(skb);
250 return 0;
251}
252
253int xfrm4_rcv(struct sk_buff *skb)
254{
Herbert Xuc4541b42007-10-17 21:28:53 -0700255 return xfrm4_rcv_spi(skb, ip_hdr(skb)->protocol, 0);
James Chapman067b2072007-07-05 17:08:05 -0700256}
257
258EXPORT_SYMBOL(xfrm4_rcv);