xref: /openbmc/linux/net/xfrm/xfrm_output.c (revision 4800cd83)
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 sk_buff *skb);
23 
24 static 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 
41 static 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 
92 resume:
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 
110 out_exit:
111 	return err;
112 error:
113 	spin_unlock_bh(&x->lock);
114 error_nolock:
115 	kfree_skb(skb);
116 	goto out_exit;
117 }
118 
119 int 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 
141 out:
142 	return err;
143 }
144 EXPORT_SYMBOL_GPL(xfrm_output_resume);
145 
146 static int xfrm_output2(struct sk_buff *skb)
147 {
148 	return xfrm_output_resume(skb, 1);
149 }
150 
151 static 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 
182 int 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 
202 int 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 
216 EXPORT_SYMBOL_GPL(xfrm_output);
217 EXPORT_SYMBOL_GPL(xfrm_inner_extract_output);
218