xref: /openbmc/linux/net/xfrm/xfrm_input.c (revision 5104d265)
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 
17 static struct kmem_cache *secpath_cachep __read_mostly;
18 
19 void __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 }
26 EXPORT_SYMBOL(__secpath_destroy);
27 
28 struct 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 }
47 EXPORT_SYMBOL(secpath_dup);
48 
49 /* Fetch spi and seq from ipsec header */
50 
51 int 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 
85 int 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 }
103 EXPORT_SYMBOL(xfrm_prepare_input);
104 
105 int 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 	__be32 seq_hi;
111 	struct xfrm_state *x;
112 	xfrm_address_t *daddr;
113 	struct xfrm_mode *inner_mode;
114 	unsigned int family;
115 	int decaps = 0;
116 	int async = 0;
117 
118 	/* A negative encap_type indicates async resumption. */
119 	if (encap_type < 0) {
120 		async = 1;
121 		x = xfrm_input_state(skb);
122 		seq = XFRM_SKB_CB(skb)->seq.input.low;
123 		goto resume;
124 	}
125 
126 	/* Allocate new secpath or COW existing one. */
127 	if (!skb->sp || atomic_read(&skb->sp->refcnt) != 1) {
128 		struct sec_path *sp;
129 
130 		sp = secpath_dup(skb->sp);
131 		if (!sp) {
132 			XFRM_INC_STATS(net, LINUX_MIB_XFRMINERROR);
133 			goto drop;
134 		}
135 		if (skb->sp)
136 			secpath_put(skb->sp);
137 		skb->sp = sp;
138 	}
139 
140 	daddr = (xfrm_address_t *)(skb_network_header(skb) +
141 				   XFRM_SPI_SKB_CB(skb)->daddroff);
142 	family = XFRM_SPI_SKB_CB(skb)->family;
143 
144 	seq = 0;
145 	if (!spi && (err = xfrm_parse_spi(skb, nexthdr, &spi, &seq)) != 0) {
146 		XFRM_INC_STATS(net, LINUX_MIB_XFRMINHDRERROR);
147 		goto drop;
148 	}
149 
150 	do {
151 		if (skb->sp->len == XFRM_MAX_DEPTH) {
152 			XFRM_INC_STATS(net, LINUX_MIB_XFRMINBUFFERERROR);
153 			goto drop;
154 		}
155 
156 		x = xfrm_state_lookup(net, skb->mark, daddr, spi, nexthdr, family);
157 		if (x == NULL) {
158 			XFRM_INC_STATS(net, LINUX_MIB_XFRMINNOSTATES);
159 			xfrm_audit_state_notfound(skb, family, spi, seq);
160 			goto drop;
161 		}
162 
163 		skb->sp->xvec[skb->sp->len++] = x;
164 
165 		spin_lock(&x->lock);
166 		if (unlikely(x->km.state == XFRM_STATE_ACQ)) {
167 			XFRM_INC_STATS(net, LINUX_MIB_XFRMACQUIREERROR);
168 			goto drop_unlock;
169 		}
170 
171 		if (unlikely(x->km.state != XFRM_STATE_VALID)) {
172 			XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEINVALID);
173 			goto drop_unlock;
174 		}
175 
176 		if ((x->encap ? x->encap->encap_type : 0) != encap_type) {
177 			XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEMISMATCH);
178 			goto drop_unlock;
179 		}
180 
181 		if (x->repl->check(x, skb, seq)) {
182 			XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATESEQERROR);
183 			goto drop_unlock;
184 		}
185 
186 		if (xfrm_state_check_expire(x)) {
187 			XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEEXPIRED);
188 			goto drop_unlock;
189 		}
190 
191 		spin_unlock(&x->lock);
192 
193 		seq_hi = htonl(xfrm_replay_seqhi(x, seq));
194 
195 		XFRM_SKB_CB(skb)->seq.input.low = seq;
196 		XFRM_SKB_CB(skb)->seq.input.hi = seq_hi;
197 
198 		skb_dst_force(skb);
199 
200 		nexthdr = x->type->input(x, skb);
201 
202 		if (nexthdr == -EINPROGRESS)
203 			return 0;
204 
205 resume:
206 		spin_lock(&x->lock);
207 		if (nexthdr <= 0) {
208 			if (nexthdr == -EBADMSG) {
209 				xfrm_audit_state_icvfail(x, skb,
210 							 x->type->proto);
211 				x->stats.integrity_failed++;
212 			}
213 			XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEPROTOERROR);
214 			goto drop_unlock;
215 		}
216 
217 		/* only the first xfrm gets the encap type */
218 		encap_type = 0;
219 
220 		if (async && x->repl->recheck(x, skb, seq)) {
221 			XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATESEQERROR);
222 			goto drop_unlock;
223 		}
224 
225 		x->repl->advance(x, seq);
226 
227 		x->curlft.bytes += skb->len;
228 		x->curlft.packets++;
229 
230 		spin_unlock(&x->lock);
231 
232 		XFRM_MODE_SKB_CB(skb)->protocol = nexthdr;
233 
234 		inner_mode = x->inner_mode;
235 
236 		if (x->sel.family == AF_UNSPEC) {
237 			inner_mode = xfrm_ip2inner_mode(x, XFRM_MODE_SKB_CB(skb)->protocol);
238 			if (inner_mode == NULL)
239 				goto drop;
240 		}
241 
242 		if (inner_mode->input(x, skb)) {
243 			XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEMODEERROR);
244 			goto drop;
245 		}
246 
247 		if (x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL) {
248 			decaps = 1;
249 			break;
250 		}
251 
252 		/*
253 		 * We need the inner address.  However, we only get here for
254 		 * transport mode so the outer address is identical.
255 		 */
256 		daddr = &x->id.daddr;
257 		family = x->outer_mode->afinfo->family;
258 
259 		err = xfrm_parse_spi(skb, nexthdr, &spi, &seq);
260 		if (err < 0) {
261 			XFRM_INC_STATS(net, LINUX_MIB_XFRMINHDRERROR);
262 			goto drop;
263 		}
264 	} while (!err);
265 
266 	nf_reset(skb);
267 
268 	if (decaps) {
269 		skb_dst_drop(skb);
270 		netif_rx(skb);
271 		return 0;
272 	} else {
273 		return x->inner_mode->afinfo->transport_finish(skb, async);
274 	}
275 
276 drop_unlock:
277 	spin_unlock(&x->lock);
278 drop:
279 	kfree_skb(skb);
280 	return 0;
281 }
282 EXPORT_SYMBOL(xfrm_input);
283 
284 int xfrm_input_resume(struct sk_buff *skb, int nexthdr)
285 {
286 	return xfrm_input(skb, nexthdr, 0, -1);
287 }
288 EXPORT_SYMBOL(xfrm_input_resume);
289 
290 void __init xfrm_input_init(void)
291 {
292 	secpath_cachep = kmem_cache_create("secpath_cache",
293 					   sizeof(struct sec_path),
294 					   0, SLAB_HWCACHE_ALIGN|SLAB_PANIC,
295 					   NULL);
296 }
297