1 /*
2 * xfrm_output.c - Common IPsec encapsulation code.
3 *
4 * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12 #include <linux/errno.h>
13 #include <linux/module.h>
14 #include <linux/netdevice.h>
15 #include <linux/netfilter.h>
16 #include <linux/skbuff.h>
17 #include <linux/slab.h>
18 #include <linux/spinlock.h>
19 #include <net/dst.h>
20 #include <net/xfrm.h>
21
22 static int xfrm_output2(struct net *net, struct sock *sk, struct sk_buff *skb);
23
xfrm_skb_check_space(struct sk_buff * skb)24 static int xfrm_skb_check_space(struct sk_buff *skb)
25 {
26 struct dst_entry *dst = skb_dst(skb);
27 int nhead = dst->header_len + LL_RESERVED_SPACE(dst->dev)
28 - skb_headroom(skb);
29 int ntail = dst->dev->needed_tailroom - skb_tailroom(skb);
30
31 if (nhead <= 0) {
32 if (ntail <= 0)
33 return 0;
34 nhead = 0;
35 } else if (ntail < 0)
36 ntail = 0;
37
38 return pskb_expand_head(skb, nhead, ntail, GFP_ATOMIC);
39 }
40
41 /* Children define the path of the packet through the
42 * Linux networking. Thus, destinations are stackable.
43 */
44
skb_dst_pop(struct sk_buff * skb)45 static struct dst_entry *skb_dst_pop(struct sk_buff *skb)
46 {
47 struct dst_entry *child = dst_clone(xfrm_dst_child(skb_dst(skb)));
48
49 skb_dst_drop(skb);
50 return child;
51 }
52
xfrm_output_one(struct sk_buff * skb,int err)53 static int xfrm_output_one(struct sk_buff *skb, int err)
54 {
55 struct dst_entry *dst = skb_dst(skb);
56 struct xfrm_state *x = dst->xfrm;
57 struct net *net = xs_net(x);
58
59 if (err <= 0)
60 goto resume;
61
62 do {
63 err = xfrm_skb_check_space(skb);
64 if (err) {
65 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
66 goto error_nolock;
67 }
68
69 skb->mark = xfrm_smark_get(skb->mark, x);
70
71 err = x->outer_mode->output(x, skb);
72 if (err) {
73 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEMODEERROR);
74 goto error_nolock;
75 }
76
77 spin_lock_bh(&x->lock);
78
79 if (unlikely(x->km.state != XFRM_STATE_VALID)) {
80 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEINVALID);
81 err = -EINVAL;
82 goto error;
83 }
84
85 err = xfrm_state_check_expire(x);
86 if (err) {
87 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEEXPIRED);
88 goto error;
89 }
90
91 err = x->repl->overflow(x, skb);
92 if (err) {
93 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATESEQERROR);
94 goto error;
95 }
96
97 x->curlft.bytes += skb->len;
98 x->curlft.packets++;
99
100 spin_unlock_bh(&x->lock);
101
102 skb_dst_force(skb);
103 if (!skb_dst(skb)) {
104 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
105 err = -EHOSTUNREACH;
106 goto error_nolock;
107 }
108
109 if (xfrm_offload(skb)) {
110 x->type_offload->encap(x, skb);
111 } else {
112 /* Inner headers are invalid now. */
113 skb->encapsulation = 0;
114
115 err = x->type->output(x, skb);
116 if (err == -EINPROGRESS)
117 goto out;
118 }
119
120 resume:
121 if (err) {
122 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEPROTOERROR);
123 goto error_nolock;
124 }
125
126 dst = skb_dst_pop(skb);
127 if (!dst) {
128 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
129 err = -EHOSTUNREACH;
130 goto error_nolock;
131 }
132 skb_dst_set(skb, dst);
133 x = dst->xfrm;
134 } while (x && !(x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL));
135
136 return 0;
137
138 error:
139 spin_unlock_bh(&x->lock);
140 error_nolock:
141 kfree_skb(skb);
142 out:
143 return err;
144 }
145
xfrm_output_resume(struct sk_buff * skb,int err)146 int xfrm_output_resume(struct sk_buff *skb, int err)
147 {
148 struct net *net = xs_net(skb_dst(skb)->xfrm);
149
150 while (likely((err = xfrm_output_one(skb, err)) == 0)) {
151 nf_reset(skb);
152
153 err = skb_dst(skb)->ops->local_out(net, skb->sk, skb);
154 if (unlikely(err != 1))
155 goto out;
156
157 if (!skb_dst(skb)->xfrm)
158 return dst_output(net, skb->sk, skb);
159
160 err = nf_hook(skb_dst(skb)->ops->family,
161 NF_INET_POST_ROUTING, net, skb->sk, skb,
162 NULL, skb_dst(skb)->dev, xfrm_output2);
163 if (unlikely(err != 1))
164 goto out;
165 }
166
167 if (err == -EINPROGRESS)
168 err = 0;
169
170 out:
171 return err;
172 }
173 EXPORT_SYMBOL_GPL(xfrm_output_resume);
174
xfrm_output2(struct net * net,struct sock * sk,struct sk_buff * skb)175 static int xfrm_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
176 {
177 return xfrm_output_resume(skb, 1);
178 }
179
xfrm_output_gso(struct net * net,struct sock * sk,struct sk_buff * skb)180 static int xfrm_output_gso(struct net *net, struct sock *sk, struct sk_buff *skb)
181 {
182 struct sk_buff *segs;
183
184 BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_SGO_CB_OFFSET);
185 BUILD_BUG_ON(sizeof(*IP6CB(skb)) > SKB_SGO_CB_OFFSET);
186 segs = skb_gso_segment(skb, 0);
187 kfree_skb(skb);
188 if (IS_ERR(segs))
189 return PTR_ERR(segs);
190 if (segs == NULL)
191 return -EINVAL;
192
193 do {
194 struct sk_buff *nskb = segs->next;
195 int err;
196
197 segs->next = NULL;
198 err = xfrm_output2(net, sk, segs);
199
200 if (unlikely(err)) {
201 kfree_skb_list(nskb);
202 return err;
203 }
204
205 segs = nskb;
206 } while (segs);
207
208 return 0;
209 }
210
xfrm_output(struct sock * sk,struct sk_buff * skb)211 int xfrm_output(struct sock *sk, struct sk_buff *skb)
212 {
213 struct net *net = dev_net(skb_dst(skb)->dev);
214 struct xfrm_state *x = skb_dst(skb)->xfrm;
215 int err;
216
217 secpath_reset(skb);
218
219 if (xfrm_dev_offload_ok(skb, x)) {
220 struct sec_path *sp;
221
222 sp = secpath_dup(skb->sp);
223 if (!sp) {
224 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
225 kfree_skb(skb);
226 return -ENOMEM;
227 }
228 if (skb->sp)
229 secpath_put(skb->sp);
230 skb->sp = sp;
231 skb->encapsulation = 1;
232
233 sp->olen++;
234 sp->xvec[skb->sp->len++] = x;
235 xfrm_state_hold(x);
236
237 if (skb_is_gso(skb)) {
238 if (skb->inner_protocol)
239 return xfrm_output_gso(net, sk, skb);
240
241 skb_shinfo(skb)->gso_type |= SKB_GSO_ESP;
242 goto out;
243 }
244
245 if (x->xso.dev && x->xso.dev->features & NETIF_F_HW_ESP_TX_CSUM)
246 goto out;
247 } else {
248 if (skb_is_gso(skb))
249 return xfrm_output_gso(net, sk, skb);
250 }
251
252 if (skb->ip_summed == CHECKSUM_PARTIAL) {
253 err = skb_checksum_help(skb);
254 if (err) {
255 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
256 kfree_skb(skb);
257 return err;
258 }
259 }
260
261 out:
262 return xfrm_output2(net, sk, skb);
263 }
264 EXPORT_SYMBOL_GPL(xfrm_output);
265
xfrm_inner_extract_output(struct xfrm_state * x,struct sk_buff * skb)266 int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb)
267 {
268 struct xfrm_mode *inner_mode;
269 if (x->sel.family == AF_UNSPEC)
270 inner_mode = xfrm_ip2inner_mode(x,
271 xfrm_af2proto(skb_dst(skb)->ops->family));
272 else
273 inner_mode = x->inner_mode;
274
275 if (inner_mode == NULL)
276 return -EAFNOSUPPORT;
277 return inner_mode->afinfo->extract_output(x, skb);
278 }
279 EXPORT_SYMBOL_GPL(xfrm_inner_extract_output);
280
xfrm_local_error(struct sk_buff * skb,int mtu)281 void xfrm_local_error(struct sk_buff *skb, int mtu)
282 {
283 unsigned int proto;
284 struct xfrm_state_afinfo *afinfo;
285
286 if (skb->protocol == htons(ETH_P_IP))
287 proto = AF_INET;
288 else if (skb->protocol == htons(ETH_P_IPV6) &&
289 skb->sk->sk_family == AF_INET6)
290 proto = AF_INET6;
291 else
292 return;
293
294 afinfo = xfrm_state_get_afinfo(proto);
295 if (afinfo) {
296 afinfo->local_error(skb, mtu);
297 rcu_read_unlock();
298 }
299 }
300 EXPORT_SYMBOL_GPL(xfrm_local_error);
301