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(skb_dst(skb)->child);
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 if (x->props.output_mark)
70 skb->mark = x->props.output_mark;
71
72 err = x->outer_mode->output(x, skb);
73 if (err) {
74 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEMODEERROR);
75 goto error_nolock;
76 }
77
78 spin_lock_bh(&x->lock);
79
80 if (unlikely(x->km.state != XFRM_STATE_VALID)) {
81 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEINVALID);
82 err = -EINVAL;
83 goto error;
84 }
85
86 err = xfrm_state_check_expire(x);
87 if (err) {
88 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEEXPIRED);
89 goto error;
90 }
91
92 err = x->repl->overflow(x, skb);
93 if (err) {
94 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATESEQERROR);
95 goto error;
96 }
97
98 x->curlft.bytes += skb->len;
99 x->curlft.packets++;
100
101 spin_unlock_bh(&x->lock);
102
103 skb_dst_force(skb);
104
105 /* Inner headers are invalid now. */
106 skb->encapsulation = 0;
107
108 err = x->type->output(x, skb);
109 if (err == -EINPROGRESS)
110 goto out;
111
112 resume:
113 if (err) {
114 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEPROTOERROR);
115 goto error_nolock;
116 }
117
118 dst = skb_dst_pop(skb);
119 if (!dst) {
120 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
121 err = -EHOSTUNREACH;
122 goto error_nolock;
123 }
124 skb_dst_set(skb, dst);
125 x = dst->xfrm;
126 } while (x && !(x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL));
127
128 return 0;
129
130 error:
131 spin_unlock_bh(&x->lock);
132 error_nolock:
133 kfree_skb(skb);
134 out:
135 return err;
136 }
137
xfrm_output_resume(struct sk_buff * skb,int err)138 int xfrm_output_resume(struct sk_buff *skb, int err)
139 {
140 struct net *net = xs_net(skb_dst(skb)->xfrm);
141
142 while (likely((err = xfrm_output_one(skb, err)) == 0)) {
143 nf_reset(skb);
144
145 err = skb_dst(skb)->ops->local_out(net, skb->sk, skb);
146 if (unlikely(err != 1))
147 goto out;
148
149 if (!skb_dst(skb)->xfrm)
150 return dst_output(net, skb->sk, skb);
151
152 err = nf_hook(skb_dst(skb)->ops->family,
153 NF_INET_POST_ROUTING, net, skb->sk, skb,
154 NULL, skb_dst(skb)->dev, xfrm_output2);
155 if (unlikely(err != 1))
156 goto out;
157 }
158
159 if (err == -EINPROGRESS)
160 err = 0;
161
162 out:
163 return err;
164 }
165 EXPORT_SYMBOL_GPL(xfrm_output_resume);
166
xfrm_output2(struct net * net,struct sock * sk,struct sk_buff * skb)167 static int xfrm_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
168 {
169 return xfrm_output_resume(skb, 1);
170 }
171
xfrm_output_gso(struct net * net,struct sock * sk,struct sk_buff * skb)172 static int xfrm_output_gso(struct net *net, struct sock *sk, struct sk_buff *skb)
173 {
174 struct sk_buff *segs;
175
176 BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_SGO_CB_OFFSET);
177 BUILD_BUG_ON(sizeof(*IP6CB(skb)) > SKB_SGO_CB_OFFSET);
178 segs = skb_gso_segment(skb, 0);
179 kfree_skb(skb);
180 if (IS_ERR(segs))
181 return PTR_ERR(segs);
182 if (segs == NULL)
183 return -EINVAL;
184
185 do {
186 struct sk_buff *nskb = segs->next;
187 int err;
188
189 segs->next = NULL;
190 err = xfrm_output2(net, sk, segs);
191
192 if (unlikely(err)) {
193 kfree_skb_list(nskb);
194 return err;
195 }
196
197 segs = nskb;
198 } while (segs);
199
200 return 0;
201 }
202
xfrm_output(struct sock * sk,struct sk_buff * skb)203 int xfrm_output(struct sock *sk, struct sk_buff *skb)
204 {
205 struct net *net = dev_net(skb_dst(skb)->dev);
206 int err;
207
208 if (skb_is_gso(skb))
209 return xfrm_output_gso(net, sk, skb);
210
211 if (skb->ip_summed == CHECKSUM_PARTIAL) {
212 err = skb_checksum_help(skb);
213 if (err) {
214 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
215 kfree_skb(skb);
216 return err;
217 }
218 }
219
220 return xfrm_output2(net, sk, skb);
221 }
222 EXPORT_SYMBOL_GPL(xfrm_output);
223
xfrm_inner_extract_output(struct xfrm_state * x,struct sk_buff * skb)224 int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb)
225 {
226 struct xfrm_mode *inner_mode;
227 if (x->sel.family == AF_UNSPEC)
228 inner_mode = xfrm_ip2inner_mode(x,
229 xfrm_af2proto(skb_dst(skb)->ops->family));
230 else
231 inner_mode = x->inner_mode;
232
233 if (inner_mode == NULL)
234 return -EAFNOSUPPORT;
235 return inner_mode->afinfo->extract_output(x, skb);
236 }
237 EXPORT_SYMBOL_GPL(xfrm_inner_extract_output);
238
xfrm_local_error(struct sk_buff * skb,int mtu)239 void xfrm_local_error(struct sk_buff *skb, int mtu)
240 {
241 unsigned int proto;
242 struct xfrm_state_afinfo *afinfo;
243
244 if (skb->protocol == htons(ETH_P_IP))
245 proto = AF_INET;
246 else if (skb->protocol == htons(ETH_P_IPV6))
247 proto = AF_INET6;
248 else
249 return;
250
251 afinfo = xfrm_state_get_afinfo(proto);
252 if (!afinfo)
253 return;
254
255 afinfo->local_error(skb, mtu);
256 xfrm_state_put_afinfo(afinfo);
257 }
258 EXPORT_SYMBOL_GPL(xfrm_local_error);
259