78e80deb7e89a25780d74a7e1691b73bb7e06b53
[linux-2.6.git] / net / ipv4 / xfrm4_input.c
1 /*
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
9  *
10  */
11
12 #include <linux/module.h>
13 #include <linux/string.h>
14 #include <linux/netfilter.h>
15 #include <linux/netfilter_ipv4.h>
16 #include <net/ip.h>
17 #include <net/xfrm.h>
18
19 int xfrm4_rcv(struct sk_buff *skb)
20 {
21         return xfrm4_rcv_encap(skb, 0);
22 }
23
24 EXPORT_SYMBOL(xfrm4_rcv);
25
26 static int xfrm4_parse_spi(struct sk_buff *skb, u8 nexthdr, __be32 *spi, __be32 *seq)
27 {
28         switch (nexthdr) {
29         case IPPROTO_IPIP:
30         case IPPROTO_IPV6:
31                 *spi = skb->nh.iph->saddr;
32                 *seq = 0;
33                 return 0;
34         }
35
36         return xfrm_parse_spi(skb, nexthdr, spi, seq);
37 }
38
39 #ifdef CONFIG_NETFILTER
40 static inline int xfrm4_rcv_encap_finish(struct sk_buff *skb)
41 {
42         struct iphdr *iph = skb->nh.iph;
43
44         if (skb->dst == NULL) {
45                 if (ip_route_input(skb, iph->daddr, iph->saddr, iph->tos,
46                                    skb->dev))
47                         goto drop;
48         }
49         return dst_input(skb);
50 drop:
51         kfree_skb(skb);
52         return NET_RX_DROP;
53 }
54 #endif
55
56 int xfrm4_rcv_encap(struct sk_buff *skb, __u16 encap_type)
57 {
58         int err;
59         __be32 spi, seq;
60         struct xfrm_state *xfrm_vec[XFRM_MAX_DEPTH];
61         struct xfrm_state *x;
62         int xfrm_nr = 0;
63         int decaps = 0;
64
65         if ((err = xfrm4_parse_spi(skb, skb->nh.iph->protocol, &spi, &seq)) != 0)
66                 goto drop;
67
68         do {
69                 struct iphdr *iph = skb->nh.iph;
70
71                 if (xfrm_nr == XFRM_MAX_DEPTH)
72                         goto drop;
73
74                 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi,
75                                 iph->protocol != IPPROTO_IPV6 ? iph->protocol : IPPROTO_IPIP, AF_INET);
76                 if (x == NULL)
77                         goto drop;
78
79                 spin_lock(&x->lock);
80                 if (unlikely(x->km.state != XFRM_STATE_VALID))
81                         goto drop_unlock;
82
83                 if ((x->encap ? x->encap->encap_type : 0) != encap_type)
84                         goto drop_unlock;
85
86                 if (x->props.replay_window && xfrm_replay_check(x, seq))
87                         goto drop_unlock;
88
89                 if (xfrm_state_check_expire(x))
90                         goto drop_unlock;
91
92                 if (x->type->input(x, skb))
93                         goto drop_unlock;
94
95                 /* only the first xfrm gets the encap type */
96                 encap_type = 0;
97
98                 if (x->props.replay_window)
99                         xfrm_replay_advance(x, seq);
100
101                 x->curlft.bytes += skb->len;
102                 x->curlft.packets++;
103
104                 spin_unlock(&x->lock);
105
106                 xfrm_vec[xfrm_nr++] = x;
107
108                 if (x->mode->input(x, skb))
109                         goto drop;
110
111                 if (x->props.mode == XFRM_MODE_TUNNEL) {
112                         decaps = 1;
113                         break;
114                 }
115
116                 if ((err = xfrm_parse_spi(skb, skb->nh.iph->protocol, &spi, &seq)) < 0)
117                         goto drop;
118         } while (!err);
119
120         /* Allocate new secpath or COW existing one. */
121
122         if (!skb->sp || atomic_read(&skb->sp->refcnt) != 1) {
123                 struct sec_path *sp;
124                 sp = secpath_dup(skb->sp);
125                 if (!sp)
126                         goto drop;
127                 if (skb->sp)
128                         secpath_put(skb->sp);
129                 skb->sp = sp;
130         }
131         if (xfrm_nr + skb->sp->len > XFRM_MAX_DEPTH)
132                 goto drop;
133
134         memcpy(skb->sp->xvec + skb->sp->len, xfrm_vec,
135                xfrm_nr * sizeof(xfrm_vec[0]));
136         skb->sp->len += xfrm_nr;
137
138         nf_reset(skb);
139
140         if (decaps) {
141                 if (!(skb->dev->flags&IFF_LOOPBACK)) {
142                         dst_release(skb->dst);
143                         skb->dst = NULL;
144                 }
145                 netif_rx(skb);
146                 return 0;
147         } else {
148 #ifdef CONFIG_NETFILTER
149                 __skb_push(skb, skb->data - skb->nh.raw);
150                 skb->nh.iph->tot_len = htons(skb->len);
151                 ip_send_check(skb->nh.iph);
152
153                 NF_HOOK(PF_INET, NF_IP_PRE_ROUTING, skb, skb->dev, NULL,
154                         xfrm4_rcv_encap_finish);
155                 return 0;
156 #else
157                 return -skb->nh.iph->protocol;
158 #endif
159         }
160
161 drop_unlock:
162         spin_unlock(&x->lock);
163         xfrm_state_put(x);
164 drop:
165         while (--xfrm_nr >= 0)
166                 xfrm_state_put(xfrm_vec[xfrm_nr]);
167
168         kfree_skb(skb);
169         return 0;
170 }