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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/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 | |
17 | static inline void ipip_ecn_decapsulate(struct sk_buff *skb) |
18 | { |
19 | struct iphdr *inner_iph = ipip_hdr(skb); |
20 | |
21 | if (INET_ECN_is_ce(XFRM_MODE_SKB_CB(skb)->tos)) |
22 | IP_ECN_set_ce(inner_iph); |
23 | } |
24 | |
25 | /* Add encapsulation header. |
26 | * |
27 | * The top IP header will be constructed per RFC 2401. |
28 | */ |
29 | static int xfrm4_mode_tunnel_output(struct xfrm_state *x, struct sk_buff *skb) |
30 | { |
31 | struct dst_entry *dst = skb_dst(skb); |
32 | struct iphdr *top_iph; |
33 | int flags; |
34 | |
35 | skb_set_network_header(skb, -x->props.header_len); |
36 | skb->mac_header = skb->network_header + |
37 | offsetof(struct iphdr, protocol); |
38 | skb->transport_header = skb->network_header + sizeof(*top_iph); |
39 | top_iph = ip_hdr(skb); |
40 | |
41 | top_iph->ihl = 5; |
42 | top_iph->version = 4; |
43 | |
44 | top_iph->protocol = xfrm_af2proto(skb_dst(skb)->ops->family); |
45 | |
46 | /* DS disclosed */ |
47 | top_iph->tos = INET_ECN_encapsulate(XFRM_MODE_SKB_CB(skb)->tos, |
48 | XFRM_MODE_SKB_CB(skb)->tos); |
49 | |
50 | flags = x->props.flags; |
51 | if (flags & XFRM_STATE_NOECN) |
52 | IP_ECN_clear(top_iph); |
53 | |
54 | top_iph->frag_off = (flags & XFRM_STATE_NOPMTUDISC) ? |
55 | 0 : (XFRM_MODE_SKB_CB(skb)->frag_off & htons(IP_DF)); |
56 | ip_select_ident(top_iph, dst->child, NULL); |
57 | |
58 | top_iph->ttl = dst_metric(dst->child, RTAX_HOPLIMIT); |
59 | |
60 | top_iph->saddr = x->props.saddr.a4; |
61 | top_iph->daddr = x->id.daddr.a4; |
62 | |
63 | return 0; |
64 | } |
65 | |
66 | static int xfrm4_mode_tunnel_input(struct xfrm_state *x, struct sk_buff *skb) |
67 | { |
68 | const unsigned char *old_mac; |
69 | int err = -EINVAL; |
70 | |
71 | if (XFRM_MODE_SKB_CB(skb)->protocol != IPPROTO_IPIP) |
72 | goto out; |
73 | |
74 | if (!pskb_may_pull(skb, sizeof(struct iphdr))) |
75 | goto out; |
76 | |
77 | if (skb_cloned(skb) && |
78 | (err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC))) |
79 | goto out; |
80 | |
81 | if (x->props.flags & XFRM_STATE_DECAP_DSCP) |
82 | ipv4_copy_dscp(XFRM_MODE_SKB_CB(skb)->tos, ipip_hdr(skb)); |
83 | if (!(x->props.flags & XFRM_STATE_NOECN)) |
84 | ipip_ecn_decapsulate(skb); |
85 | |
86 | old_mac = skb_mac_header(skb); |
87 | skb_set_mac_header(skb, -skb->mac_len); |
88 | memmove(skb_mac_header(skb), old_mac, skb->mac_len); |
89 | skb_reset_network_header(skb); |
90 | err = 0; |
91 | |
92 | out: |
93 | return err; |
94 | } |
95 | |
96 | static struct xfrm_mode xfrm4_tunnel_mode = { |
97 | .input2 = xfrm4_mode_tunnel_input, |
98 | .input = xfrm_prepare_input, |
99 | .output2 = xfrm4_mode_tunnel_output, |
100 | .output = xfrm4_prepare_output, |
101 | .owner = THIS_MODULE, |
102 | .encap = XFRM_MODE_TUNNEL, |
103 | .flags = XFRM_MODE_FLAG_TUNNEL, |
104 | }; |
105 | |
106 | static int __init xfrm4_mode_tunnel_init(void) |
107 | { |
108 | return xfrm_register_mode(&xfrm4_tunnel_mode, AF_INET); |
109 | } |
110 | |
111 | static void __exit xfrm4_mode_tunnel_exit(void) |
112 | { |
113 | int err; |
114 | |
115 | err = xfrm_unregister_mode(&xfrm4_tunnel_mode, AF_INET); |
116 | BUG_ON(err); |
117 | } |
118 | |
119 | module_init(xfrm4_mode_tunnel_init); |
120 | module_exit(xfrm4_mode_tunnel_exit); |
121 | MODULE_LICENSE("GPL"); |
122 | MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_TUNNEL); |
123 |
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