Linux Kernel  3.7.1
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xfrm_input.c
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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 
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 }
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 }
48 
49 /* Fetch spi and seq from ipsec header */
50 
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 }
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;
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) {
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) {
147  goto drop;
148  }
149 
150  do {
151  if (skb->sp->len == XFRM_MAX_DEPTH) {
153  goto drop;
154  }
155 
156  x = xfrm_state_lookup(net, skb->mark, daddr, spi, nexthdr, family);
157  if (x == NULL) {
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_VALID)) {
168  goto drop_unlock;
169  }
170 
171  if ((x->encap ? x->encap->encap_type : 0) != encap_type) {
173  goto drop_unlock;
174  }
175 
176  if (x->repl->check(x, skb, seq)) {
178  goto drop_unlock;
179  }
180 
181  if (xfrm_state_check_expire(x)) {
183  goto drop_unlock;
184  }
185 
186  spin_unlock(&x->lock);
187 
188  seq_hi = htonl(xfrm_replay_seqhi(x, seq));
189 
190  XFRM_SKB_CB(skb)->seq.input.low = seq;
191  XFRM_SKB_CB(skb)->seq.input.hi = seq_hi;
192 
193  skb_dst_force(skb);
194 
195  nexthdr = x->type->input(x, skb);
196 
197  if (nexthdr == -EINPROGRESS)
198  return 0;
199 
200 resume:
201  spin_lock(&x->lock);
202  if (nexthdr <= 0) {
203  if (nexthdr == -EBADMSG) {
204  xfrm_audit_state_icvfail(x, skb,
205  x->type->proto);
206  x->stats.integrity_failed++;
207  }
209  goto drop_unlock;
210  }
211 
212  /* only the first xfrm gets the encap type */
213  encap_type = 0;
214 
215  if (async && x->repl->recheck(x, skb, seq)) {
217  goto drop_unlock;
218  }
219 
220  x->repl->advance(x, seq);
221 
222  x->curlft.bytes += skb->len;
223  x->curlft.packets++;
224 
225  spin_unlock(&x->lock);
226 
227  XFRM_MODE_SKB_CB(skb)->protocol = nexthdr;
228 
229  inner_mode = x->inner_mode;
230 
231  if (x->sel.family == AF_UNSPEC) {
232  inner_mode = xfrm_ip2inner_mode(x, XFRM_MODE_SKB_CB(skb)->protocol);
233  if (inner_mode == NULL)
234  goto drop;
235  }
236 
237  if (inner_mode->input(x, skb)) {
239  goto drop;
240  }
241 
242  if (x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL) {
243  decaps = 1;
244  break;
245  }
246 
247  /*
248  * We need the inner address. However, we only get here for
249  * transport mode so the outer address is identical.
250  */
251  daddr = &x->id.daddr;
252  family = x->outer_mode->afinfo->family;
253 
254  err = xfrm_parse_spi(skb, nexthdr, &spi, &seq);
255  if (err < 0) {
257  goto drop;
258  }
259  } while (!err);
260 
261  nf_reset(skb);
262 
263  if (decaps) {
264  skb_dst_drop(skb);
265  netif_rx(skb);
266  return 0;
267  } else {
268  return x->inner_mode->afinfo->transport_finish(skb, async);
269  }
270 
271 drop_unlock:
272  spin_unlock(&x->lock);
273 drop:
274  kfree_skb(skb);
275  return 0;
276 }
278 
280 {
281  return xfrm_input(skb, nexthdr, 0, -1);
282 }
284 
286 {
287  secpath_cachep = kmem_cache_create("secpath_cache",
288  sizeof(struct sec_path),
290  NULL);
291 }