xfrm4_input.c revision e905a9edab7f4f14f9213b52234e4a346c690911 
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
19int xfrm4_rcv(struct sk_buff *skb)
20{
21	return xfrm4_rcv_encap(skb, 0);
22}
23
24EXPORT_SYMBOL(xfrm4_rcv);
25
26static int xfrm4_parse_spi(struct sk_buff *skb, u8 nexthdr, __be32 *spi, __be32 *seq)
27{
28	switch (nexthdr) {
29	case IPPROTO_IPIP:
30		*spi = skb->nh.iph->saddr;
31		*seq = 0;
32		return 0;
33	}
34
35	return xfrm_parse_spi(skb, nexthdr, spi, seq);
36}
37
38#ifdef CONFIG_NETFILTER
39static inline int xfrm4_rcv_encap_finish(struct sk_buff *skb)
40{
41	struct iphdr *iph = skb->nh.iph;
42
43	if (skb->dst == NULL) {
44		if (ip_route_input(skb, iph->daddr, iph->saddr, iph->tos,
45				   skb->dev))
46			goto drop;
47	}
48	return dst_input(skb);
49drop:
50	kfree_skb(skb);
51	return NET_RX_DROP;
52}
53#endif
54
55int xfrm4_rcv_encap(struct sk_buff *skb, __u16 encap_type)
56{
57	int err;
58	__be32 spi, seq;
59	struct xfrm_state *xfrm_vec[XFRM_MAX_DEPTH];
60	struct xfrm_state *x;
61	int xfrm_nr = 0;
62	int decaps = 0;
63
64	if ((err = xfrm4_parse_spi(skb, skb->nh.iph->protocol, &spi, &seq)) != 0)
65		goto drop;
66
67	do {
68		struct iphdr *iph = skb->nh.iph;
69
70		if (xfrm_nr == XFRM_MAX_DEPTH)
71			goto drop;
72
73		x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, iph->protocol, AF_INET);
74		if (x == NULL)
75			goto drop;
76
77		spin_lock(&x->lock);
78		if (unlikely(x->km.state != XFRM_STATE_VALID))
79			goto drop_unlock;
80
81		if ((x->encap ? x->encap->encap_type : 0) != encap_type)
82			goto drop_unlock;
83
84		if (x->props.replay_window && xfrm_replay_check(x, seq))
85			goto drop_unlock;
86
87		if (xfrm_state_check_expire(x))
88			goto drop_unlock;
89
90		if (x->type->input(x, skb))
91			goto drop_unlock;
92
93		/* only the first xfrm gets the encap type */
94		encap_type = 0;
95
96		if (x->props.replay_window)
97			xfrm_replay_advance(x, seq);
98
99		x->curlft.bytes += skb->len;
100		x->curlft.packets++;
101
102		spin_unlock(&x->lock);
103
104		xfrm_vec[xfrm_nr++] = x;
105
106		if (x->mode->input(x, skb))
107			goto drop;
108
109		if (x->props.mode == XFRM_MODE_TUNNEL) {
110			decaps = 1;
111			break;
112		}
113
114		if ((err = xfrm_parse_spi(skb, skb->nh.iph->protocol, &spi, &seq)) < 0)
115			goto drop;
116	} while (!err);
117
118	/* Allocate new secpath or COW existing one. */
119
120	if (!skb->sp || atomic_read(&skb->sp->refcnt) != 1) {
121		struct sec_path *sp;
122		sp = secpath_dup(skb->sp);
123		if (!sp)
124			goto drop;
125		if (skb->sp)
126			secpath_put(skb->sp);
127		skb->sp = sp;
128	}
129	if (xfrm_nr + skb->sp->len > XFRM_MAX_DEPTH)
130		goto drop;
131
132	memcpy(skb->sp->xvec + skb->sp->len, xfrm_vec,
133	       xfrm_nr * sizeof(xfrm_vec[0]));
134	skb->sp->len += xfrm_nr;
135
136	nf_reset(skb);
137
138	if (decaps) {
139		if (!(skb->dev->flags&IFF_LOOPBACK)) {
140			dst_release(skb->dst);
141			skb->dst = NULL;
142		}
143		netif_rx(skb);
144		return 0;
145	} else {
146#ifdef CONFIG_NETFILTER
147		__skb_push(skb, skb->data - skb->nh.raw);
148		skb->nh.iph->tot_len = htons(skb->len);
149		ip_send_check(skb->nh.iph);
150
151		NF_HOOK(PF_INET, NF_IP_PRE_ROUTING, skb, skb->dev, NULL,
152			xfrm4_rcv_encap_finish);
153		return 0;
154#else
155		return -skb->nh.iph->protocol;
156#endif
157	}
158
159drop_unlock:
160	spin_unlock(&x->lock);
161	xfrm_state_put(x);
162drop:
163	while (--xfrm_nr >= 0)
164		xfrm_state_put(xfrm_vec[xfrm_nr]);
165
166	kfree_skb(skb);
167	return 0;
168}
169