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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/gfp.h> | |
8 | #include <linux/init.h> | |
9 | #include <linux/kernel.h> | |
10 | #include <linux/module.h> | |
11 | #include <linux/skbuff.h> | |
12 | #include <linux/stringify.h> | |
13 | #include <net/dst.h> | |
14 | #include <net/inet_ecn.h> | |
15 | #include <net/ip.h> | |
16 | #include <net/xfrm.h> | |
17 | ||
18 | static inline void ipip_ecn_decapsulate(struct sk_buff *skb) | |
19 | { | |
20 | struct iphdr *inner_iph = ipip_hdr(skb); | |
21 | ||
22 | if (INET_ECN_is_ce(XFRM_MODE_SKB_CB(skb)->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. | |
29 | */ | |
30 | static int xfrm4_mode_tunnel_output(struct xfrm_state *x, struct sk_buff *skb) | |
31 | { | |
32 | struct dst_entry *dst = skb_dst(skb); | |
33 | struct iphdr *top_iph; | |
34 | int flags; | |
35 | ||
36 | skb_set_network_header(skb, -x->props.header_len); | |
37 | skb->mac_header = skb->network_header + | |
38 | offsetof(struct iphdr, protocol); | |
39 | skb->transport_header = skb->network_header + sizeof(*top_iph); | |
40 | top_iph = ip_hdr(skb); | |
41 | ||
42 | top_iph->ihl = 5; | |
43 | top_iph->version = 4; | |
44 | ||
45 | top_iph->protocol = xfrm_af2proto(skb_dst(skb)->ops->family); | |
46 | ||
47 | /* DS disclosing depends on XFRM_SA_XFLAG_DONT_ENCAP_DSCP */ | |
48 | if (x->props.extra_flags & XFRM_SA_XFLAG_DONT_ENCAP_DSCP) | |
49 | top_iph->tos = 0; | |
50 | else | |
51 | top_iph->tos = XFRM_MODE_SKB_CB(skb)->tos; | |
52 | top_iph->tos = INET_ECN_encapsulate(top_iph->tos, | |
53 | XFRM_MODE_SKB_CB(skb)->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 : (XFRM_MODE_SKB_CB(skb)->frag_off & htons(IP_DF)); | |
61 | ||
62 | top_iph->ttl = ip4_dst_hoplimit(dst->child); | |
63 | ||
64 | top_iph->saddr = x->props.saddr.a4; | |
65 | top_iph->daddr = x->id.daddr.a4; | |
66 | ip_select_ident(dev_net(dst->dev), skb, NULL); | |
67 | ||
68 | return 0; | |
69 | } | |
70 | ||
71 | static int xfrm4_mode_tunnel_input(struct xfrm_state *x, struct sk_buff *skb) | |
72 | { | |
73 | int err = -EINVAL; | |
74 | ||
75 | if (XFRM_MODE_SKB_CB(skb)->protocol != IPPROTO_IPIP) | |
76 | goto out; | |
77 | ||
78 | if (!pskb_may_pull(skb, sizeof(struct iphdr))) | |
79 | goto out; | |
80 | ||
81 | err = skb_unclone(skb, GFP_ATOMIC); | |
82 | if (err) | |
83 | goto out; | |
84 | ||
85 | if (x->props.flags & XFRM_STATE_DECAP_DSCP) | |
86 | ipv4_copy_dscp(XFRM_MODE_SKB_CB(skb)->tos, ipip_hdr(skb)); | |
87 | if (!(x->props.flags & XFRM_STATE_NOECN)) | |
88 | ipip_ecn_decapsulate(skb); | |
89 | ||
90 | skb_reset_network_header(skb); | |
91 | skb_mac_header_rebuild(skb); | |
92 | ||
93 | err = 0; | |
94 | ||
95 | out: | |
96 | return err; | |
97 | } | |
98 | ||
99 | static struct xfrm_mode xfrm4_tunnel_mode = { | |
100 | .input2 = xfrm4_mode_tunnel_input, | |
101 | .input = xfrm_prepare_input, | |
102 | .output2 = xfrm4_mode_tunnel_output, | |
103 | .output = xfrm4_prepare_output, | |
104 | .owner = THIS_MODULE, | |
105 | .encap = XFRM_MODE_TUNNEL, | |
106 | .flags = XFRM_MODE_FLAG_TUNNEL, | |
107 | }; | |
108 | ||
109 | static int __init xfrm4_mode_tunnel_init(void) | |
110 | { | |
111 | return xfrm_register_mode(&xfrm4_tunnel_mode, AF_INET); | |
112 | } | |
113 | ||
114 | static void __exit xfrm4_mode_tunnel_exit(void) | |
115 | { | |
116 | int err; | |
117 | ||
118 | err = xfrm_unregister_mode(&xfrm4_tunnel_mode, AF_INET); | |
119 | BUG_ON(err); | |
120 | } | |
121 | ||
122 | module_init(xfrm4_mode_tunnel_init); | |
123 | module_exit(xfrm4_mode_tunnel_exit); | |
124 | MODULE_LICENSE("GPL"); | |
125 | MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_TUNNEL); |