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_state_check_space(struct xfrm_state *x, 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_state_check_space(x, 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		err = xfrm_state_check_expire(x);
65		if (err) {
66			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEEXPIRED);
67			goto error;
68		}
69
70		if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
71			XFRM_SKB_CB(skb)->seq.output = ++x->replay.oseq;
72			if (unlikely(x->replay.oseq == 0)) {
73				XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATESEQERROR);
74				x->replay.oseq--;
75				xfrm_audit_state_replay_overflow(x, skb);
76				err = -EOVERFLOW;
77				goto error;
78			}
79			if (xfrm_aevent_is_on(net))
80				xfrm_replay_notify(x, XFRM_REPLAY_UPDATE);
81		}
82
83		x->curlft.bytes += skb->len;
84		x->curlft.packets++;
85
86		spin_unlock_bh(&x->lock);
87
88		err = x->type->output(x, skb);
89		if (err == -EINPROGRESS)
90			goto out_exit;
91
92resume:
93		if (err) {
94			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEPROTOERROR);
95			goto error_nolock;
96		}
97
98		dst = skb_dst_pop(skb);
99		if (!dst) {
100			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
101			err = -EHOSTUNREACH;
102			goto error_nolock;
103		}
104		skb_dst_set(skb, dst_clone(dst));
105		x = dst->xfrm;
106	} while (x && !(x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL));
107
108	err = 0;
109
110out_exit:
111	return err;
112error:
113	spin_unlock_bh(&x->lock);
114error_nolock:
115	kfree_skb(skb);
116	goto out_exit;
117}
118
119int xfrm_output_resume(struct sk_buff *skb, int err)
120{
121	while (likely((err = xfrm_output_one(skb, err)) == 0)) {
122		nf_reset(skb);
123
124		err = skb_dst(skb)->ops->local_out(skb);
125		if (unlikely(err != 1))
126			goto out;
127
128		if (!skb_dst(skb)->xfrm)
129			return dst_output(skb);
130
131		err = nf_hook(skb_dst(skb)->ops->family,
132			      NF_INET_POST_ROUTING, skb,
133			      NULL, skb_dst(skb)->dev, xfrm_output2);
134		if (unlikely(err != 1))
135			goto out;
136	}
137
138	if (err == -EINPROGRESS)
139		err = 0;
140
141out:
142	return err;
143}
144EXPORT_SYMBOL_GPL(xfrm_output_resume);
145
146static int xfrm_output2(struct sk_buff *skb)
147{
148	return xfrm_output_resume(skb, 1);
149}
150
151static int xfrm_output_gso(struct sk_buff *skb)
152{
153	struct sk_buff *segs;
154
155	segs = skb_gso_segment(skb, 0);
156	kfree_skb(skb);
157	if (IS_ERR(segs))
158		return PTR_ERR(segs);
159
160	do {
161		struct sk_buff *nskb = segs->next;
162		int err;
163
164		segs->next = NULL;
165		err = xfrm_output2(segs);
166
167		if (unlikely(err)) {
168			while ((segs = nskb)) {
169				nskb = segs->next;
170				segs->next = NULL;
171				kfree_skb(segs);
172			}
173			return err;
174		}
175
176		segs = nskb;
177	} while (segs);
178
179	return 0;
180}
181
182int xfrm_output(struct sk_buff *skb)
183{
184	struct net *net = dev_net(skb_dst(skb)->dev);
185	int err;
186
187	if (skb_is_gso(skb))
188		return xfrm_output_gso(skb);
189
190	if (skb->ip_summed == CHECKSUM_PARTIAL) {
191		err = skb_checksum_help(skb);
192		if (err) {
193			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
194			kfree_skb(skb);
195			return err;
196		}
197	}
198
199	return xfrm_output2(skb);
200}
201
202int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb)
203{
204	struct xfrm_mode *inner_mode;
205	if (x->sel.family == AF_UNSPEC)
206		inner_mode = xfrm_ip2inner_mode(x,
207				xfrm_af2proto(skb_dst(skb)->ops->family));
208	else
209		inner_mode = x->inner_mode;
210
211	if (inner_mode == NULL)
212		return -EAFNOSUPPORT;
213	return inner_mode->afinfo->extract_output(x, skb);
214}
215
216EXPORT_SYMBOL_GPL(xfrm_output);
217EXPORT_SYMBOL_GPL(xfrm_inner_extract_output);
218