xref: /linux/net/xfrm/xfrm_input.c (revision 827634added7f38b7d724cab1dccdb2b004c13c3) 
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 static DEFINE_SPINLOCK(xfrm_input_afinfo_lock);
20 static struct xfrm_input_afinfo __rcu *xfrm_input_afinfo[NPROTO];
21 
22 int xfrm_input_register_afinfo(struct xfrm_input_afinfo *afinfo)
23 {
24 	int err = 0;
25 
26 	if (unlikely(afinfo == NULL))
27 		return -EINVAL;
28 	if (unlikely(afinfo->family >= NPROTO))
29 		return -EAFNOSUPPORT;
30 	spin_lock_bh(&xfrm_input_afinfo_lock);
31 	if (unlikely(xfrm_input_afinfo[afinfo->family] != NULL))
32 		err = -ENOBUFS;
33 	else
34 		rcu_assign_pointer(xfrm_input_afinfo[afinfo->family], afinfo);
35 	spin_unlock_bh(&xfrm_input_afinfo_lock);
36 	return err;
37 }
38 EXPORT_SYMBOL(xfrm_input_register_afinfo);
39 
40 int xfrm_input_unregister_afinfo(struct xfrm_input_afinfo *afinfo)
41 {
42 	int err = 0;
43 
44 	if (unlikely(afinfo == NULL))
45 		return -EINVAL;
46 	if (unlikely(afinfo->family >= NPROTO))
47 		return -EAFNOSUPPORT;
48 	spin_lock_bh(&xfrm_input_afinfo_lock);
49 	if (likely(xfrm_input_afinfo[afinfo->family] != NULL)) {
50 		if (unlikely(xfrm_input_afinfo[afinfo->family] != afinfo))
51 			err = -EINVAL;
52 		else
53 			RCU_INIT_POINTER(xfrm_input_afinfo[afinfo->family], NULL);
54 	}
55 	spin_unlock_bh(&xfrm_input_afinfo_lock);
56 	synchronize_rcu();
57 	return err;
58 }
59 EXPORT_SYMBOL(xfrm_input_unregister_afinfo);
60 
61 static struct xfrm_input_afinfo *xfrm_input_get_afinfo(unsigned int family)
62 {
63 	struct xfrm_input_afinfo *afinfo;
64 
65 	if (unlikely(family >= NPROTO))
66 		return NULL;
67 	rcu_read_lock();
68 	afinfo = rcu_dereference(xfrm_input_afinfo[family]);
69 	if (unlikely(!afinfo))
70 		rcu_read_unlock();
71 	return afinfo;
72 }
73 
74 static void xfrm_input_put_afinfo(struct xfrm_input_afinfo *afinfo)
75 {
76 	rcu_read_unlock();
77 }
78 
79 static int xfrm_rcv_cb(struct sk_buff *skb, unsigned int family, u8 protocol,
80 		       int err)
81 {
82 	int ret;
83 	struct xfrm_input_afinfo *afinfo = xfrm_input_get_afinfo(family);
84 
85 	if (!afinfo)
86 		return -EAFNOSUPPORT;
87 
88 	ret = afinfo->callback(skb, protocol, err);
89 	xfrm_input_put_afinfo(afinfo);
90 
91 	return ret;
92 }
93 
94 void __secpath_destroy(struct sec_path *sp)
95 {
96 	int i;
97 	for (i = 0; i < sp->len; i++)
98 		xfrm_state_put(sp->xvec[i]);
99 	kmem_cache_free(secpath_cachep, sp);
100 }
101 EXPORT_SYMBOL(__secpath_destroy);
102 
103 struct sec_path *secpath_dup(struct sec_path *src)
104 {
105 	struct sec_path *sp;
106 
107 	sp = kmem_cache_alloc(secpath_cachep, GFP_ATOMIC);
108 	if (!sp)
109 		return NULL;
110 
111 	sp->len = 0;
112 	if (src) {
113 		int i;
114 
115 		memcpy(sp, src, sizeof(*sp));
116 		for (i = 0; i < sp->len; i++)
117 			xfrm_state_hold(sp->xvec[i]);
118 	}
119 	atomic_set(&sp->refcnt, 1);
120 	return sp;
121 }
122 EXPORT_SYMBOL(secpath_dup);
123 
124 /* Fetch spi and seq from ipsec header */
125 
126 int xfrm_parse_spi(struct sk_buff *skb, u8 nexthdr, __be32 *spi, __be32 *seq)
127 {
128 	int offset, offset_seq;
129 	int hlen;
130 
131 	switch (nexthdr) {
132 	case IPPROTO_AH:
133 		hlen = sizeof(struct ip_auth_hdr);
134 		offset = offsetof(struct ip_auth_hdr, spi);
135 		offset_seq = offsetof(struct ip_auth_hdr, seq_no);
136 		break;
137 	case IPPROTO_ESP:
138 		hlen = sizeof(struct ip_esp_hdr);
139 		offset = offsetof(struct ip_esp_hdr, spi);
140 		offset_seq = offsetof(struct ip_esp_hdr, seq_no);
141 		break;
142 	case IPPROTO_COMP:
143 		if (!pskb_may_pull(skb, sizeof(struct ip_comp_hdr)))
144 			return -EINVAL;
145 		*spi = htonl(ntohs(*(__be16 *)(skb_transport_header(skb) + 2)));
146 		*seq = 0;
147 		return 0;
148 	default:
149 		return 1;
150 	}
151 
152 	if (!pskb_may_pull(skb, hlen))
153 		return -EINVAL;
154 
155 	*spi = *(__be32 *)(skb_transport_header(skb) + offset);
156 	*seq = *(__be32 *)(skb_transport_header(skb) + offset_seq);
157 	return 0;
158 }
159 
160 int xfrm_prepare_input(struct xfrm_state *x, struct sk_buff *skb)
161 {
162 	struct xfrm_mode *inner_mode = x->inner_mode;
163 	int err;
164 
165 	err = x->outer_mode->afinfo->extract_input(x, skb);
166 	if (err)
167 		return err;
168 
169 	if (x->sel.family == AF_UNSPEC) {
170 		inner_mode = xfrm_ip2inner_mode(x, XFRM_MODE_SKB_CB(skb)->protocol);
171 		if (inner_mode == NULL)
172 			return -EAFNOSUPPORT;
173 	}
174 
175 	skb->protocol = inner_mode->afinfo->eth_proto;
176 	return inner_mode->input2(x, skb);
177 }
178 EXPORT_SYMBOL(xfrm_prepare_input);
179 
180 int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
181 {
182 	struct net *net = dev_net(skb->dev);
183 	int err;
184 	__be32 seq;
185 	__be32 seq_hi;
186 	struct xfrm_state *x = NULL;
187 	xfrm_address_t *daddr;
188 	struct xfrm_mode *inner_mode;
189 	unsigned int family;
190 	int decaps = 0;
191 	int async = 0;
192 
193 	/* A negative encap_type indicates async resumption. */
194 	if (encap_type < 0) {
195 		async = 1;
196 		x = xfrm_input_state(skb);
197 		seq = XFRM_SKB_CB(skb)->seq.input.low;
198 		family = x->outer_mode->afinfo->family;
199 		goto resume;
200 	}
201 
202 	daddr = (xfrm_address_t *)(skb_network_header(skb) +
203 				   XFRM_SPI_SKB_CB(skb)->daddroff);
204 	family = XFRM_SPI_SKB_CB(skb)->family;
205 
206 	/* Allocate new secpath or COW existing one. */
207 	if (!skb->sp || atomic_read(&skb->sp->refcnt) != 1) {
208 		struct sec_path *sp;
209 
210 		sp = secpath_dup(skb->sp);
211 		if (!sp) {
212 			XFRM_INC_STATS(net, LINUX_MIB_XFRMINERROR);
213 			goto drop;
214 		}
215 		if (skb->sp)
216 			secpath_put(skb->sp);
217 		skb->sp = sp;
218 	}
219 
220 	seq = 0;
221 	if (!spi && (err = xfrm_parse_spi(skb, nexthdr, &spi, &seq)) != 0) {
222 		XFRM_INC_STATS(net, LINUX_MIB_XFRMINHDRERROR);
223 		goto drop;
224 	}
225 
226 	do {
227 		if (skb->sp->len == XFRM_MAX_DEPTH) {
228 			XFRM_INC_STATS(net, LINUX_MIB_XFRMINBUFFERERROR);
229 			goto drop;
230 		}
231 
232 		x = xfrm_state_lookup(net, skb->mark, daddr, spi, nexthdr, family);
233 		if (x == NULL) {
234 			XFRM_INC_STATS(net, LINUX_MIB_XFRMINNOSTATES);
235 			xfrm_audit_state_notfound(skb, family, spi, seq);
236 			goto drop;
237 		}
238 
239 		skb->sp->xvec[skb->sp->len++] = x;
240 
241 		spin_lock(&x->lock);
242 		if (unlikely(x->km.state == XFRM_STATE_ACQ)) {
243 			XFRM_INC_STATS(net, LINUX_MIB_XFRMACQUIREERROR);
244 			goto drop_unlock;
245 		}
246 
247 		if (unlikely(x->km.state != XFRM_STATE_VALID)) {
248 			XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEINVALID);
249 			goto drop_unlock;
250 		}
251 
252 		if ((x->encap ? x->encap->encap_type : 0) != encap_type) {
253 			XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEMISMATCH);
254 			goto drop_unlock;
255 		}
256 
257 		if (x->repl->check(x, skb, seq)) {
258 			XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATESEQERROR);
259 			goto drop_unlock;
260 		}
261 
262 		if (xfrm_state_check_expire(x)) {
263 			XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEEXPIRED);
264 			goto drop_unlock;
265 		}
266 
267 		spin_unlock(&x->lock);
268 
269 		if (xfrm_tunnel_check(skb, x, family)) {
270 			XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEMODEERROR);
271 			goto drop;
272 		}
273 
274 		seq_hi = htonl(xfrm_replay_seqhi(x, seq));
275 
276 		XFRM_SKB_CB(skb)->seq.input.low = seq;
277 		XFRM_SKB_CB(skb)->seq.input.hi = seq_hi;
278 
279 		skb_dst_force(skb);
280 
281 		nexthdr = x->type->input(x, skb);
282 
283 		if (nexthdr == -EINPROGRESS)
284 			return 0;
285 resume:
286 		spin_lock(&x->lock);
287 		if (nexthdr <= 0) {
288 			if (nexthdr == -EBADMSG) {
289 				xfrm_audit_state_icvfail(x, skb,
290 							 x->type->proto);
291 				x->stats.integrity_failed++;
292 			}
293 			XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEPROTOERROR);
294 			goto drop_unlock;
295 		}
296 
297 		/* only the first xfrm gets the encap type */
298 		encap_type = 0;
299 
300 		if (async && x->repl->recheck(x, skb, seq)) {
301 			XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATESEQERROR);
302 			goto drop_unlock;
303 		}
304 
305 		x->repl->advance(x, seq);
306 
307 		x->curlft.bytes += skb->len;
308 		x->curlft.packets++;
309 
310 		spin_unlock(&x->lock);
311 
312 		XFRM_MODE_SKB_CB(skb)->protocol = nexthdr;
313 
314 		inner_mode = x->inner_mode;
315 
316 		if (x->sel.family == AF_UNSPEC) {
317 			inner_mode = xfrm_ip2inner_mode(x, XFRM_MODE_SKB_CB(skb)->protocol);
318 			if (inner_mode == NULL)
319 				goto drop;
320 		}
321 
322 		if (inner_mode->input(x, skb)) {
323 			XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEMODEERROR);
324 			goto drop;
325 		}
326 
327 		if (x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL) {
328 			decaps = 1;
329 			break;
330 		}
331 
332 		/*
333 		 * We need the inner address.  However, we only get here for
334 		 * transport mode so the outer address is identical.
335 		 */
336 		daddr = &x->id.daddr;
337 		family = x->outer_mode->afinfo->family;
338 
339 		err = xfrm_parse_spi(skb, nexthdr, &spi, &seq);
340 		if (err < 0) {
341 			XFRM_INC_STATS(net, LINUX_MIB_XFRMINHDRERROR);
342 			goto drop;
343 		}
344 	} while (!err);
345 
346 	err = xfrm_rcv_cb(skb, family, x->type->proto, 0);
347 	if (err)
348 		goto drop;
349 
350 	nf_reset(skb);
351 
352 	if (decaps) {
353 		skb_dst_drop(skb);
354 		netif_rx(skb);
355 		return 0;
356 	} else {
357 		return x->inner_mode->afinfo->transport_finish(skb, async);
358 	}
359 
360 drop_unlock:
361 	spin_unlock(&x->lock);
362 drop:
363 	xfrm_rcv_cb(skb, family, x && x->type ? x->type->proto : nexthdr, -1);
364 	kfree_skb(skb);
365 	return 0;
366 }
367 EXPORT_SYMBOL(xfrm_input);
368 
369 int xfrm_input_resume(struct sk_buff *skb, int nexthdr)
370 {
371 	return xfrm_input(skb, nexthdr, 0, -1);
372 }
373 EXPORT_SYMBOL(xfrm_input_resume);
374 
375 void __init xfrm_input_init(void)
376 {
377 	secpath_cachep = kmem_cache_create("secpath_cache",
378 					   sizeof(struct sec_path),
379 					   0, SLAB_HWCACHE_ALIGN|SLAB_PANIC,
380 					   NULL);
381 }
382