Root/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/slab.h>
18#include <linux/spinlock.h>
19#include <net/dst.h>
20#include <net/xfrm.h>
21
22static int xfrm_output2(struct sk_buff *skb);
23
24static 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
41static int xfrm_output_one(struct sk_buff *skb, int err)
42{
43    struct dst_entry *dst = skb_dst(skb);
44    struct xfrm_state *x = dst->xfrm;
45    struct net *net = xs_net(x);
46
47    if (err <= 0)
48        goto resume;
49
50    do {
51        err = xfrm_skb_check_space(skb);
52        if (err) {
53            XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
54            goto error_nolock;
55        }
56
57        err = x->outer_mode->output(x, skb);
58        if (err) {
59            XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEMODEERROR);
60            goto error_nolock;
61        }
62
63        spin_lock_bh(&x->lock);
64
65        if (unlikely(x->km.state != XFRM_STATE_VALID)) {
66            XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEINVALID);
67            err = -EINVAL;
68            goto error;
69        }
70
71        err = xfrm_state_check_expire(x);
72        if (err) {
73            XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEEXPIRED);
74            goto error;
75        }
76
77        err = x->repl->overflow(x, skb);
78        if (err) {
79            XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATESEQERROR);
80            goto error;
81        }
82
83        x->curlft.bytes += skb->len;
84        x->curlft.packets++;
85
86        spin_unlock_bh(&x->lock);
87
88        skb_dst_force(skb);
89
90        err = x->type->output(x, skb);
91        if (err == -EINPROGRESS)
92            goto out;
93
94resume:
95        if (err) {
96            XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEPROTOERROR);
97            goto error_nolock;
98        }
99
100        dst = skb_dst_pop(skb);
101        if (!dst) {
102            XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
103            err = -EHOSTUNREACH;
104            goto error_nolock;
105        }
106        skb_dst_set(skb, dst);
107        x = dst->xfrm;
108    } while (x && !(x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL));
109
110    return 0;
111
112error:
113    spin_unlock_bh(&x->lock);
114error_nolock:
115    kfree_skb(skb);
116out:
117    return err;
118}
119
120int xfrm_output_resume(struct sk_buff *skb, int err)
121{
122    while (likely((err = xfrm_output_one(skb, err)) == 0)) {
123        nf_reset(skb);
124
125        err = skb_dst(skb)->ops->local_out(skb);
126        if (unlikely(err != 1))
127            goto out;
128
129        if (!skb_dst(skb)->xfrm)
130            return dst_output(skb);
131
132        err = nf_hook(skb_dst(skb)->ops->family,
133                  NF_INET_POST_ROUTING, skb,
134                  NULL, skb_dst(skb)->dev, xfrm_output2);
135        if (unlikely(err != 1))
136            goto out;
137    }
138
139    if (err == -EINPROGRESS)
140        err = 0;
141
142out:
143    return err;
144}
145EXPORT_SYMBOL_GPL(xfrm_output_resume);
146
147static int xfrm_output2(struct sk_buff *skb)
148{
149    return xfrm_output_resume(skb, 1);
150}
151
152static int xfrm_output_gso(struct sk_buff *skb)
153{
154    struct sk_buff *segs;
155
156    segs = skb_gso_segment(skb, 0);
157    kfree_skb(skb);
158    if (IS_ERR(segs))
159        return PTR_ERR(segs);
160
161    do {
162        struct sk_buff *nskb = segs->next;
163        int err;
164
165        segs->next = NULL;
166        err = xfrm_output2(segs);
167
168        if (unlikely(err)) {
169            while ((segs = nskb)) {
170                nskb = segs->next;
171                segs->next = NULL;
172                kfree_skb(segs);
173            }
174            return err;
175        }
176
177        segs = nskb;
178    } while (segs);
179
180    return 0;
181}
182
183int xfrm_output(struct sk_buff *skb)
184{
185    struct net *net = dev_net(skb_dst(skb)->dev);
186    int err;
187
188    if (skb_is_gso(skb))
189        return xfrm_output_gso(skb);
190
191    if (skb->ip_summed == CHECKSUM_PARTIAL) {
192        err = skb_checksum_help(skb);
193        if (err) {
194            XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
195            kfree_skb(skb);
196            return err;
197        }
198    }
199
200    return xfrm_output2(skb);
201}
202
203int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb)
204{
205    struct xfrm_mode *inner_mode;
206    if (x->sel.family == AF_UNSPEC)
207        inner_mode = xfrm_ip2inner_mode(x,
208                xfrm_af2proto(skb_dst(skb)->ops->family));
209    else
210        inner_mode = x->inner_mode;
211
212    if (inner_mode == NULL)
213        return -EAFNOSUPPORT;
214    return inner_mode->afinfo->extract_output(x, skb);
215}
216
217void xfrm_local_error(struct sk_buff *skb, int mtu)
218{
219    unsigned int proto;
220    struct xfrm_state_afinfo *afinfo;
221
222    if (skb->protocol == htons(ETH_P_IP))
223        proto = AF_INET;
224    else if (skb->protocol == htons(ETH_P_IPV6))
225        proto = AF_INET6;
226    else
227        return;
228
229    afinfo = xfrm_state_get_afinfo(proto);
230    if (!afinfo)
231        return;
232
233    afinfo->local_error(skb, mtu);
234    xfrm_state_put_afinfo(afinfo);
235}
236
237EXPORT_SYMBOL_GPL(xfrm_output);
238EXPORT_SYMBOL_GPL(xfrm_inner_extract_output);
239EXPORT_SYMBOL_GPL(xfrm_local_error);
240

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