Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * xfrm4_output.c - Common IPsec encapsulation code for IPv4. | |
3 | * Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au> | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or | |
6 | * modify it under the terms of the GNU General Public License | |
7 | * as published by the Free Software Foundation; either version | |
8 | * 2 of the License, or (at your option) any later version. | |
9 | */ | |
10 | ||
16a6677f | 11 | #include <linux/compiler.h> |
1da177e4 LT |
12 | #include <linux/skbuff.h> |
13 | #include <linux/spinlock.h> | |
16a6677f | 14 | #include <linux/netfilter_ipv4.h> |
1da177e4 LT |
15 | #include <net/inet_ecn.h> |
16 | #include <net/ip.h> | |
17 | #include <net/xfrm.h> | |
18 | #include <net/icmp.h> | |
19 | ||
20 | /* Add encapsulation header. | |
21 | * | |
22 | * In transport mode, the IP header will be moved forward to make space | |
23 | * for the encapsulation header. | |
24 | * | |
25 | * In tunnel mode, the top IP header will be constructed per RFC 2401. | |
26 | * The following fields in it shall be filled in by x->type->output: | |
27 | * tot_len | |
28 | * check | |
29 | * | |
30 | * On exit, skb->h will be set to the start of the payload to be processed | |
31 | * by x->type->output and skb->nh will be set to the top IP header. | |
32 | */ | |
33 | static void xfrm4_encap(struct sk_buff *skb) | |
34 | { | |
35 | struct dst_entry *dst = skb->dst; | |
36 | struct xfrm_state *x = dst->xfrm; | |
37 | struct iphdr *iph, *top_iph; | |
dd87147e | 38 | int flags; |
1da177e4 LT |
39 | |
40 | iph = skb->nh.iph; | |
41 | skb->h.ipiph = iph; | |
42 | ||
43 | skb->nh.raw = skb_push(skb, x->props.header_len); | |
44 | top_iph = skb->nh.iph; | |
45 | ||
46 | if (!x->props.mode) { | |
47 | skb->h.raw += iph->ihl*4; | |
48 | memmove(top_iph, iph, iph->ihl*4); | |
49 | return; | |
50 | } | |
51 | ||
52 | top_iph->ihl = 5; | |
53 | top_iph->version = 4; | |
54 | ||
55 | /* DS disclosed */ | |
56 | top_iph->tos = INET_ECN_encapsulate(iph->tos, iph->tos); | |
dd87147e HX |
57 | |
58 | flags = x->props.flags; | |
59 | if (flags & XFRM_STATE_NOECN) | |
1da177e4 LT |
60 | IP_ECN_clear(top_iph); |
61 | ||
dd87147e HX |
62 | top_iph->frag_off = (flags & XFRM_STATE_NOPMTUDISC) ? |
63 | 0 : (iph->frag_off & htons(IP_DF)); | |
1da177e4 LT |
64 | if (!top_iph->frag_off) |
65 | __ip_select_ident(top_iph, dst, 0); | |
66 | ||
67 | top_iph->ttl = dst_metric(dst->child, RTAX_HOPLIMIT); | |
68 | ||
69 | top_iph->saddr = x->props.saddr.a4; | |
70 | top_iph->daddr = x->id.daddr.a4; | |
71 | top_iph->protocol = IPPROTO_IPIP; | |
72 | ||
73 | memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options)); | |
74 | } | |
75 | ||
76 | static int xfrm4_tunnel_check_size(struct sk_buff *skb) | |
77 | { | |
78 | int mtu, ret = 0; | |
79 | struct dst_entry *dst; | |
80 | struct iphdr *iph = skb->nh.iph; | |
81 | ||
82 | if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE) | |
83 | goto out; | |
84 | ||
85 | IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE; | |
86 | ||
87 | if (!(iph->frag_off & htons(IP_DF)) || skb->local_df) | |
88 | goto out; | |
89 | ||
90 | dst = skb->dst; | |
91 | mtu = dst_mtu(dst); | |
92 | if (skb->len > mtu) { | |
93 | icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu)); | |
94 | ret = -EMSGSIZE; | |
95 | } | |
96 | out: | |
97 | return ret; | |
98 | } | |
99 | ||
16a6677f | 100 | static int xfrm4_output_one(struct sk_buff *skb) |
1da177e4 LT |
101 | { |
102 | struct dst_entry *dst = skb->dst; | |
103 | struct xfrm_state *x = dst->xfrm; | |
104 | int err; | |
105 | ||
106 | if (skb->ip_summed == CHECKSUM_HW) { | |
107 | err = skb_checksum_help(skb, 0); | |
108 | if (err) | |
109 | goto error_nolock; | |
110 | } | |
111 | ||
112 | if (x->props.mode) { | |
113 | err = xfrm4_tunnel_check_size(skb); | |
114 | if (err) | |
115 | goto error_nolock; | |
116 | } | |
117 | ||
16a6677f PM |
118 | do { |
119 | spin_lock_bh(&x->lock); | |
120 | err = xfrm_state_check(x, skb); | |
121 | if (err) | |
122 | goto error; | |
1da177e4 | 123 | |
16a6677f | 124 | xfrm4_encap(skb); |
1da177e4 | 125 | |
16a6677f PM |
126 | err = x->type->output(x, skb); |
127 | if (err) | |
128 | goto error; | |
1da177e4 | 129 | |
16a6677f PM |
130 | x->curlft.bytes += skb->len; |
131 | x->curlft.packets++; | |
1da177e4 | 132 | |
16a6677f | 133 | spin_unlock_bh(&x->lock); |
1da177e4 | 134 | |
16a6677f PM |
135 | if (!(skb->dst = dst_pop(dst))) { |
136 | err = -EHOSTUNREACH; | |
137 | goto error_nolock; | |
138 | } | |
139 | dst = skb->dst; | |
140 | x = dst->xfrm; | |
141 | } while (x && !x->props.mode); | |
142 | ||
3e3850e9 | 143 | IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED; |
16a6677f | 144 | err = 0; |
1da177e4 LT |
145 | |
146 | out_exit: | |
147 | return err; | |
148 | error: | |
149 | spin_unlock_bh(&x->lock); | |
150 | error_nolock: | |
151 | kfree_skb(skb); | |
152 | goto out_exit; | |
153 | } | |
16a6677f | 154 | |
5c901daa | 155 | int xfrm4_output_finish(struct sk_buff *skb) |
16a6677f PM |
156 | { |
157 | int err; | |
158 | ||
159 | while (likely((err = xfrm4_output_one(skb)) == 0)) { | |
160 | nf_reset(skb); | |
161 | ||
162 | err = nf_hook(PF_INET, NF_IP_LOCAL_OUT, &skb, NULL, | |
163 | skb->dst->dev, dst_output); | |
164 | if (unlikely(err != 1)) | |
165 | break; | |
166 | ||
167 | if (!skb->dst->xfrm) | |
168 | return dst_output(skb); | |
169 | ||
170 | err = nf_hook(PF_INET, NF_IP_POST_ROUTING, &skb, NULL, | |
171 | skb->dst->dev, xfrm4_output_finish); | |
172 | if (unlikely(err != 1)) | |
173 | break; | |
174 | } | |
175 | ||
176 | return err; | |
177 | } | |
178 | ||
179 | int xfrm4_output(struct sk_buff *skb) | |
180 | { | |
181 | return NF_HOOK(PF_INET, NF_IP_POST_ROUTING, skb, NULL, skb->dst->dev, | |
182 | xfrm4_output_finish); | |
183 | } |