1/*
2 * xfrm_input.c
3 *
4 * Changes:
5 * 	YOSHIFUJI Hideaki @USAGI
6 * 		Split up af-specific portion
7 *
8 */
9
10#include <linux/slab.h>
11#include <linux/module.h>
12#include <linux/netdevice.h>
13#include <net/dst.h>
14#include <net/ip.h>
15#include <net/xfrm.h>
16
17static struct kmem_cache *secpath_cachep __read_mostly;
18
19void __secpath_destroy(struct sec_path *sp)
20{
21	int i;
22	for (i = 0; i < sp->len; i++)
23		xfrm_state_put(sp->xvec[i]);
24	kmem_cache_free(secpath_cachep, sp);
25}
26EXPORT_SYMBOL(__secpath_destroy);
27
28struct sec_path *secpath_dup(struct sec_path *src)
29{
30	struct sec_path *sp;
31
32	sp = kmem_cache_alloc(secpath_cachep, GFP_ATOMIC);
33	if (!sp)
34		return NULL;
35
36	sp->len = 0;
37	if (src) {
38		int i;
39
40		memcpy(sp, src, sizeof(*sp));
41		for (i = 0; i < sp->len; i++)
42			xfrm_state_hold(sp->xvec[i]);
43	}
44	atomic_set(&sp->refcnt, 1);
45	return sp;
46}
47EXPORT_SYMBOL(secpath_dup);
48
49/* Fetch spi and seq from ipsec header */
50
51int xfrm_parse_spi(struct sk_buff *skb, u8 nexthdr, __be32 *spi, __be32 *seq)
52{
53	int offset, offset_seq;
54	int hlen;
55
56	switch (nexthdr) {
57	case IPPROTO_AH:
58		hlen = sizeof(struct ip_auth_hdr);
59		offset = offsetof(struct ip_auth_hdr, spi);
60		offset_seq = offsetof(struct ip_auth_hdr, seq_no);
61		break;
62	case IPPROTO_ESP:
63		hlen = sizeof(struct ip_esp_hdr);
64		offset = offsetof(struct ip_esp_hdr, spi);
65		offset_seq = offsetof(struct ip_esp_hdr, seq_no);
66		break;
67	case IPPROTO_COMP:
68		if (!pskb_may_pull(skb, sizeof(struct ip_comp_hdr)))
69			return -EINVAL;
70		*spi = htonl(ntohs(*(__be16*)(skb_transport_header(skb) + 2)));
71		*seq = 0;
72		return 0;
73	default:
74		return 1;
75	}
76
77	if (!pskb_may_pull(skb, hlen))
78		return -EINVAL;
79
80	*spi = *(__be32*)(skb_transport_header(skb) + offset);
81	*seq = *(__be32*)(skb_transport_header(skb) + offset_seq);
82	return 0;
83}
84
85int xfrm_prepare_input(struct xfrm_state *x, struct sk_buff *skb)
86{
87	struct xfrm_mode *inner_mode = x->inner_mode;
88	int err;
89
90	err = x->outer_mode->afinfo->extract_input(x, skb);
91	if (err)
92		return err;
93
94	if (x->sel.family == AF_UNSPEC) {
95		inner_mode = xfrm_ip2inner_mode(x, XFRM_MODE_SKB_CB(skb)->protocol);
96		if (inner_mode == NULL)
97			return -EAFNOSUPPORT;
98	}
99
100	skb->protocol = inner_mode->afinfo->eth_proto;
101	return inner_mode->input2(x, skb);
102}
103EXPORT_SYMBOL(xfrm_prepare_input);
104
105int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
106{
107	struct net *net = dev_net(skb->dev);
108	int err;
109	__be32 seq;
110	struct xfrm_state *x;
111	xfrm_address_t *daddr;
112	struct xfrm_mode *inner_mode;
113	unsigned int family;
114	int decaps = 0;
115	int async = 0;
116
117	/* A negative encap_type indicates async resumption. */
118	if (encap_type < 0) {
119		async = 1;
120		x = xfrm_input_state(skb);
121		seq = XFRM_SKB_CB(skb)->seq.input;
122		goto resume;
123	}
124
125	/* Allocate new secpath or COW existing one. */
126	if (!skb->sp || atomic_read(&skb->sp->refcnt) != 1) {
127		struct sec_path *sp;
128
129		sp = secpath_dup(skb->sp);
130		if (!sp) {
131			XFRM_INC_STATS(net, LINUX_MIB_XFRMINERROR);
132			goto drop;
133		}
134		if (skb->sp)
135			secpath_put(skb->sp);
136		skb->sp = sp;
137	}
138
139	daddr = (xfrm_address_t *)(skb_network_header(skb) +
140				   XFRM_SPI_SKB_CB(skb)->daddroff);
141	family = XFRM_SPI_SKB_CB(skb)->family;
142
143	seq = 0;
144	if (!spi && (err = xfrm_parse_spi(skb, nexthdr, &spi, &seq)) != 0) {
145		XFRM_INC_STATS(net, LINUX_MIB_XFRMINHDRERROR);
146		goto drop;
147	}
148
149	do {
150		if (skb->sp->len == XFRM_MAX_DEPTH) {
151			XFRM_INC_STATS(net, LINUX_MIB_XFRMINBUFFERERROR);
152			goto drop;
153		}
154
155		x = xfrm_state_lookup(net, skb->mark, daddr, spi, nexthdr, family);
156		if (x == NULL) {
157			XFRM_INC_STATS(net, LINUX_MIB_XFRMINNOSTATES);
158			xfrm_audit_state_notfound(skb, family, spi, seq);
159			goto drop;
160		}
161
162		skb->sp->xvec[skb->sp->len++] = x;
163
164		spin_lock(&x->lock);
165		if (unlikely(x->km.state != XFRM_STATE_VALID)) {
166			XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEINVALID);
167			goto drop_unlock;
168		}
169
170		if ((x->encap ? x->encap->encap_type : 0) != encap_type) {
171			XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEMISMATCH);
172			goto drop_unlock;
173		}
174
175		if (x->props.replay_window && xfrm_replay_check(x, skb, seq)) {
176			XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATESEQERROR);
177			goto drop_unlock;
178		}
179
180		if (xfrm_state_check_expire(x)) {
181			XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEEXPIRED);
182			goto drop_unlock;
183		}
184
185		spin_unlock(&x->lock);
186
187		XFRM_SKB_CB(skb)->seq.input = seq;
188
189		nexthdr = x->type->input(x, skb);
190
191		if (nexthdr == -EINPROGRESS)
192			return 0;
193
194resume:
195		spin_lock(&x->lock);
196		if (nexthdr <= 0) {
197			if (nexthdr == -EBADMSG) {
198				xfrm_audit_state_icvfail(x, skb,
199							 x->type->proto);
200				x->stats.integrity_failed++;
201			}
202			XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEPROTOERROR);
203			goto drop_unlock;
204		}
205
206		/* only the first xfrm gets the encap type */
207		encap_type = 0;
208
209		if (x->props.replay_window)
210			xfrm_replay_advance(x, seq);
211
212		x->curlft.bytes += skb->len;
213		x->curlft.packets++;
214
215		spin_unlock(&x->lock);
216
217		XFRM_MODE_SKB_CB(skb)->protocol = nexthdr;
218
219		inner_mode = x->inner_mode;
220
221		if (x->sel.family == AF_UNSPEC) {
222			inner_mode = xfrm_ip2inner_mode(x, XFRM_MODE_SKB_CB(skb)->protocol);
223			if (inner_mode == NULL)
224				goto drop;
225		}
226
227		if (inner_mode->input(x, skb)) {
228			XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEMODEERROR);
229			goto drop;
230		}
231
232		if (x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL) {
233			decaps = 1;
234			break;
235		}
236
237		/*
238		 * We need the inner address.  However, we only get here for
239		 * transport mode so the outer address is identical.
240		 */
241		daddr = &x->id.daddr;
242		family = x->outer_mode->afinfo->family;
243
244		err = xfrm_parse_spi(skb, nexthdr, &spi, &seq);
245		if (err < 0) {
246			XFRM_INC_STATS(net, LINUX_MIB_XFRMINHDRERROR);
247			goto drop;
248		}
249	} while (!err);
250
251	nf_reset(skb);
252
253	if (decaps) {
254		skb_dst_drop(skb);
255		netif_rx(skb);
256		return 0;
257	} else {
258		return x->inner_mode->afinfo->transport_finish(skb, async);
259	}
260
261drop_unlock:
262	spin_unlock(&x->lock);
263drop:
264	kfree_skb(skb);
265	return 0;
266}
267EXPORT_SYMBOL(xfrm_input);
268
269int xfrm_input_resume(struct sk_buff *skb, int nexthdr)
270{
271	return xfrm_input(skb, nexthdr, 0, -1);
272}
273EXPORT_SYMBOL(xfrm_input_resume);
274
275void __init xfrm_input_init(void)
276{
277	secpath_cachep = kmem_cache_create("secpath_cache",
278					   sizeof(struct sec_path),
279					   0, SLAB_HWCACHE_ALIGN|SLAB_PANIC,
280					   NULL);
281}
282