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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 disclosed */ |
48 | top_iph->tos = INET_ECN_encapsulate(XFRM_MODE_SKB_CB(skb)->tos, |
49 | XFRM_MODE_SKB_CB(skb)->tos); |
50 | |
51 | flags = x->props.flags; |
52 | if (flags & XFRM_STATE_NOECN) |
53 | IP_ECN_clear(top_iph); |
54 | |
55 | top_iph->frag_off = (flags & XFRM_STATE_NOPMTUDISC) ? |
56 | 0 : (XFRM_MODE_SKB_CB(skb)->frag_off & htons(IP_DF)); |
57 | ip_select_ident(top_iph, dst->child, NULL); |
58 | |
59 | top_iph->ttl = dst_metric(dst->child, RTAX_HOPLIMIT); |
60 | |
61 | top_iph->saddr = x->props.saddr.a4; |
62 | top_iph->daddr = x->id.daddr.a4; |
63 | |
64 | return 0; |
65 | } |
66 | |
67 | static int xfrm4_mode_tunnel_input(struct xfrm_state *x, struct sk_buff *skb) |
68 | { |
69 | const unsigned char *old_mac; |
70 | int err = -EINVAL; |
71 | |
72 | if (XFRM_MODE_SKB_CB(skb)->protocol != IPPROTO_IPIP) |
73 | goto out; |
74 | |
75 | if (!pskb_may_pull(skb, sizeof(struct iphdr))) |
76 | goto out; |
77 | |
78 | if (skb_cloned(skb) && |
79 | (err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC))) |
80 | goto out; |
81 | |
82 | if (x->props.flags & XFRM_STATE_DECAP_DSCP) |
83 | ipv4_copy_dscp(XFRM_MODE_SKB_CB(skb)->tos, ipip_hdr(skb)); |
84 | if (!(x->props.flags & XFRM_STATE_NOECN)) |
85 | ipip_ecn_decapsulate(skb); |
86 | |
87 | old_mac = skb_mac_header(skb); |
88 | skb_set_mac_header(skb, -skb->mac_len); |
89 | memmove(skb_mac_header(skb), old_mac, skb->mac_len); |
90 | skb_reset_network_header(skb); |
91 | err = 0; |
92 | |
93 | out: |
94 | return err; |
95 | } |
96 | |
97 | static struct xfrm_mode xfrm4_tunnel_mode = { |
98 | .input2 = xfrm4_mode_tunnel_input, |
99 | .input = xfrm_prepare_input, |
100 | .output2 = xfrm4_mode_tunnel_output, |
101 | .output = xfrm4_prepare_output, |
102 | .owner = THIS_MODULE, |
103 | .encap = XFRM_MODE_TUNNEL, |
104 | .flags = XFRM_MODE_FLAG_TUNNEL, |
105 | }; |
106 | |
107 | static int __init xfrm4_mode_tunnel_init(void) |
108 | { |
109 | return xfrm_register_mode(&xfrm4_tunnel_mode, AF_INET); |
110 | } |
111 | |
112 | static void __exit xfrm4_mode_tunnel_exit(void) |
113 | { |
114 | int err; |
115 | |
116 | err = xfrm_unregister_mode(&xfrm4_tunnel_mode, AF_INET); |
117 | BUG_ON(err); |
118 | } |
119 | |
120 | module_init(xfrm4_mode_tunnel_init); |
121 | module_exit(xfrm4_mode_tunnel_exit); |
122 | MODULE_LICENSE("GPL"); |
123 | MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_TUNNEL); |
124 |
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