tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * xfrm4_mode_tunnel.c - Tunnel mode encapsulation for IPv4.
3 *
4 * Copyright (c) 2004-2006 Herbert Xu <herbert@gondor.apana.org.au>
5 */
6
7#include <linux/init.h>
8#include <linux/kernel.h>
9#include <linux/module.h>
10#include <linux/skbuff.h>
11#include <linux/stringify.h>
12#include <net/dst.h>
13#include <net/inet_ecn.h>
14#include <net/ip.h>
15#include <net/xfrm.h>
16
17static inline void ipip_ecn_decapsulate(struct sk_buff *skb)
18{
19 struct iphdr *outer_iph = skb->nh.iph;
20 struct iphdr *inner_iph = skb->h.ipiph;
21
22 if (INET_ECN_is_ce(outer_iph->tos))
23 IP_ECN_set_ce(inner_iph);
24}
25
26/* Add encapsulation header.
27 *
28 * The top IP header will be constructed per RFC 2401. The following fields
29 * in it shall be filled in by x->type->output:
30 * tot_len
31 * check
32 *
33 * On exit, skb->h will be set to the start of the payload to be processed
34 * by x->type->output and skb->nh will be set to the top IP header.
35 */
36static int xfrm4_tunnel_output(struct sk_buff *skb)
37{
38 struct dst_entry *dst = skb->dst;
39 struct xfrm_state *x = dst->xfrm;
40 struct iphdr *iph, *top_iph;
41 int flags;
42
43 iph = skb->nh.iph;
44 skb->h.ipiph = iph;
45
46 skb->nh.raw = skb_push(skb, x->props.header_len);
47 top_iph = skb->nh.iph;
48
49 top_iph->ihl = 5;
50 top_iph->version = 4;
51
52 /* DS disclosed */
53 top_iph->tos = INET_ECN_encapsulate(iph->tos, iph->tos);
54
55 flags = x->props.flags;
56 if (flags & XFRM_STATE_NOECN)
57 IP_ECN_clear(top_iph);
58
59 top_iph->frag_off = (flags & XFRM_STATE_NOPMTUDISC) ?
60 0 : (iph->frag_off & htons(IP_DF));
61 if (!top_iph->frag_off)
62 __ip_select_ident(top_iph, dst->child, 0);
63
64 top_iph->ttl = dst_metric(dst->child, RTAX_HOPLIMIT);
65
66 top_iph->saddr = x->props.saddr.a4;
67 top_iph->daddr = x->id.daddr.a4;
68 top_iph->protocol = IPPROTO_IPIP;
69
70 memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
71 return 0;
72}
73
74static int xfrm4_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
75{
76 struct iphdr *iph = skb->nh.iph;
77 int err = -EINVAL;
78
79 if (iph->protocol != IPPROTO_IPIP)
80 goto out;
81 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
82 goto out;
83
84 if (skb_cloned(skb) &&
85 (err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
86 goto out;
87
88 if (x->props.flags & XFRM_STATE_DECAP_DSCP)
89 ipv4_copy_dscp(iph, skb->h.ipiph);
90 if (!(x->props.flags & XFRM_STATE_NOECN))
91 ipip_ecn_decapsulate(skb);
92 skb->mac.raw = memmove(skb->data - skb->mac_len,
93 skb->mac.raw, skb->mac_len);
94 skb->nh.raw = skb->data;
95 memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
96 err = 0;
97
98out:
99 return err;
100}
101
102static struct xfrm_mode xfrm4_tunnel_mode = {
103 .input = xfrm4_tunnel_input,
104 .output = xfrm4_tunnel_output,
105 .owner = THIS_MODULE,
106 .encap = XFRM_MODE_TUNNEL,
107};
108
109static int __init xfrm4_tunnel_init(void)
110{
111 return xfrm_register_mode(&xfrm4_tunnel_mode, AF_INET);
112}
113
114static void __exit xfrm4_tunnel_exit(void)
115{
116 int err;
117
118 err = xfrm_unregister_mode(&xfrm4_tunnel_mode, AF_INET);
119 BUG_ON(err);
120}
121
122module_init(xfrm4_tunnel_init);
123module_exit(xfrm4_tunnel_exit);
124MODULE_LICENSE("GPL");
125MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_TUNNEL);