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 sock *sk, 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->sk, 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 sock *sk, struct sk_buff *skb)
148{
149	return xfrm_output_resume(skb, 1);
150}
151
152static int xfrm_output_gso(struct sock *sk, struct sk_buff *skb)
153{
154	struct sk_buff *segs;
155
156	BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_SGO_CB_OFFSET);
157	BUILD_BUG_ON(sizeof(*IP6CB(skb)) > SKB_SGO_CB_OFFSET);
158	segs = skb_gso_segment(skb, 0);
159	kfree_skb(skb);
160	if (IS_ERR(segs))
161		return PTR_ERR(segs);
162	if (segs == NULL)
163		return -EINVAL;
164
165	do {
166		struct sk_buff *nskb = segs->next;
167		int err;
168
169		segs->next = NULL;
170		err = xfrm_output2(sk, segs);
171
172		if (unlikely(err)) {
173			kfree_skb_list(nskb);
174			return err;
175		}
176
177		segs = nskb;
178	} while (segs);
179
180	return 0;
181}
182
183int xfrm_output(struct sock *sk, 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(sk, 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(sk, skb);
201}
202EXPORT_SYMBOL_GPL(xfrm_output);
203
204int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb)
205{
206	struct xfrm_mode *inner_mode;
207	if (x->sel.family == AF_UNSPEC)
208		inner_mode = xfrm_ip2inner_mode(x,
209				xfrm_af2proto(skb_dst(skb)->ops->family));
210	else
211		inner_mode = x->inner_mode;
212
213	if (inner_mode == NULL)
214		return -EAFNOSUPPORT;
215	return inner_mode->afinfo->extract_output(x, skb);
216}
217EXPORT_SYMBOL_GPL(xfrm_inner_extract_output);
218
219void xfrm_local_error(struct sk_buff *skb, int mtu)
220{
221	unsigned int proto;
222	struct xfrm_state_afinfo *afinfo;
223
224	if (skb->protocol == htons(ETH_P_IP))
225		proto = AF_INET;
226	else if (skb->protocol == htons(ETH_P_IPV6))
227		proto = AF_INET6;
228	else
229		return;
230
231	afinfo = xfrm_state_get_afinfo(proto);
232	if (!afinfo)
233		return;
234
235	afinfo->local_error(skb, mtu);
236	xfrm_state_put_afinfo(afinfo);
237}
238EXPORT_SYMBOL_GPL(xfrm_local_error);
239