ipsec: Fix pskb_expand_head corruption in xfrm_state_check_space
[linux-2.6.git] / net / xfrm / xfrm_output.c
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/spinlock.h>
18 #include <net/dst.h>
19 #include <net/xfrm.h>
20
21 static int xfrm_output2(struct sk_buff *skb);
22
23 static int xfrm_state_check_space(struct xfrm_state *x, struct sk_buff *skb)
24 {
25         struct dst_entry *dst = skb->dst;
26         int nhead = dst->header_len + LL_RESERVED_SPACE(dst->dev)
27                 - skb_headroom(skb);
28         int ntail = dst->dev->needed_tailroom - skb_tailroom(skb);
29
30         if (nhead <= 0) {
31                 if (ntail <= 0)
32                         return 0;
33                 nhead = 0;
34         } else if (ntail < 0)
35                 ntail = 0;
36
37         return pskb_expand_head(skb, nhead, ntail, GFP_ATOMIC);
38 }
39
40 static int xfrm_output_one(struct sk_buff *skb, int err)
41 {
42         struct dst_entry *dst = skb->dst;
43         struct xfrm_state *x = dst->xfrm;
44
45         if (err <= 0)
46                 goto resume;
47
48         do {
49                 err = xfrm_state_check_space(x, skb);
50                 if (err) {
51                         XFRM_INC_STATS(LINUX_MIB_XFRMOUTERROR);
52                         goto error_nolock;
53                 }
54
55                 err = x->outer_mode->output(x, skb);
56                 if (err) {
57                         XFRM_INC_STATS(LINUX_MIB_XFRMOUTSTATEMODEERROR);
58                         goto error_nolock;
59                 }
60
61                 spin_lock_bh(&x->lock);
62                 err = xfrm_state_check_expire(x);
63                 if (err) {
64                         XFRM_INC_STATS(LINUX_MIB_XFRMOUTSTATEEXPIRED);
65                         goto error;
66                 }
67
68                 if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
69                         XFRM_SKB_CB(skb)->seq.output = ++x->replay.oseq;
70                         if (unlikely(x->replay.oseq == 0)) {
71                                 XFRM_INC_STATS(LINUX_MIB_XFRMOUTSTATESEQERROR);
72                                 x->replay.oseq--;
73                                 xfrm_audit_state_replay_overflow(x, skb);
74                                 err = -EOVERFLOW;
75                                 goto error;
76                         }
77                         if (xfrm_aevent_is_on())
78                                 xfrm_replay_notify(x, XFRM_REPLAY_UPDATE);
79                 }
80
81                 x->curlft.bytes += skb->len;
82                 x->curlft.packets++;
83
84                 spin_unlock_bh(&x->lock);
85
86                 err = x->type->output(x, skb);
87                 if (err == -EINPROGRESS)
88                         goto out_exit;
89
90 resume:
91                 if (err) {
92                         XFRM_INC_STATS(LINUX_MIB_XFRMOUTSTATEPROTOERROR);
93                         goto error_nolock;
94                 }
95
96                 if (!(skb->dst = dst_pop(dst))) {
97                         XFRM_INC_STATS(LINUX_MIB_XFRMOUTERROR);
98                         err = -EHOSTUNREACH;
99                         goto error_nolock;
100                 }
101                 dst = skb->dst;
102                 x = dst->xfrm;
103         } while (x && !(x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL));
104
105         err = 0;
106
107 out_exit:
108         return err;
109 error:
110         spin_unlock_bh(&x->lock);
111 error_nolock:
112         kfree_skb(skb);
113         goto out_exit;
114 }
115
116 int xfrm_output_resume(struct sk_buff *skb, int err)
117 {
118         while (likely((err = xfrm_output_one(skb, err)) == 0)) {
119                 nf_reset(skb);
120
121                 err = skb->dst->ops->local_out(skb);
122                 if (unlikely(err != 1))
123                         goto out;
124
125                 if (!skb->dst->xfrm)
126                         return dst_output(skb);
127
128                 err = nf_hook(skb->dst->ops->family,
129                               NF_INET_POST_ROUTING, skb,
130                               NULL, skb->dst->dev, xfrm_output2);
131                 if (unlikely(err != 1))
132                         goto out;
133         }
134
135         if (err == -EINPROGRESS)
136                 err = 0;
137
138 out:
139         return err;
140 }
141 EXPORT_SYMBOL_GPL(xfrm_output_resume);
142
143 static int xfrm_output2(struct sk_buff *skb)
144 {
145         return xfrm_output_resume(skb, 1);
146 }
147
148 static int xfrm_output_gso(struct sk_buff *skb)
149 {
150         struct sk_buff *segs;
151
152         segs = skb_gso_segment(skb, 0);
153         kfree_skb(skb);
154         if (IS_ERR(segs))
155                 return PTR_ERR(segs);
156
157         do {
158                 struct sk_buff *nskb = segs->next;
159                 int err;
160
161                 segs->next = NULL;
162                 err = xfrm_output2(segs);
163
164                 if (unlikely(err)) {
165                         while ((segs = nskb)) {
166                                 nskb = segs->next;
167                                 segs->next = NULL;
168                                 kfree_skb(segs);
169                         }
170                         return err;
171                 }
172
173                 segs = nskb;
174         } while (segs);
175
176         return 0;
177 }
178
179 int xfrm_output(struct sk_buff *skb)
180 {
181         int err;
182
183         if (skb_is_gso(skb))
184                 return xfrm_output_gso(skb);
185
186         if (skb->ip_summed == CHECKSUM_PARTIAL) {
187                 err = skb_checksum_help(skb);
188                 if (err) {
189                         XFRM_INC_STATS(LINUX_MIB_XFRMOUTERROR);
190                         kfree_skb(skb);
191                         return err;
192                 }
193         }
194
195         return xfrm_output2(skb);
196 }
197
198 int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb)
199 {
200         struct xfrm_mode *inner_mode;
201         if (x->sel.family == AF_UNSPEC)
202                 inner_mode = xfrm_ip2inner_mode(x,
203                                 xfrm_af2proto(skb->dst->ops->family));
204         else
205                 inner_mode = x->inner_mode;
206
207         if (inner_mode == NULL)
208                 return -EAFNOSUPPORT;
209         return inner_mode->afinfo->extract_output(x, skb);
210 }
211
212 EXPORT_SYMBOL_GPL(xfrm_output);
213 EXPORT_SYMBOL_GPL(xfrm_inner_extract_output);