1 | /* |
2 | * xfrm4_mode_beet.c - BEET mode encapsulation for IPv4. |
3 | * |
4 | * Copyright (c) 2006 Diego Beltrami <diego.beltrami@gmail.com> |
5 | * Miika Komu <miika@iki.fi> |
6 | * Herbert Xu <herbert@gondor.apana.org.au> |
7 | * Abhinav Pathak <abhinav.pathak@hiit.fi> |
8 | * Jeff Ahrenholz <ahrenholz@gmail.com> |
9 | */ |
10 | |
11 | #include <linux/init.h> |
12 | #include <linux/kernel.h> |
13 | #include <linux/module.h> |
14 | #include <linux/skbuff.h> |
15 | #include <linux/stringify.h> |
16 | #include <net/dst.h> |
17 | #include <net/ip.h> |
18 | #include <net/xfrm.h> |
19 | |
20 | static void (struct sk_buff *skb) |
21 | { |
22 | struct iphdr *iph = ip_hdr(skb); |
23 | |
24 | iph->ihl = 5; |
25 | iph->version = 4; |
26 | |
27 | iph->protocol = XFRM_MODE_SKB_CB(skb)->protocol; |
28 | iph->tos = XFRM_MODE_SKB_CB(skb)->tos; |
29 | |
30 | iph->id = XFRM_MODE_SKB_CB(skb)->id; |
31 | iph->frag_off = XFRM_MODE_SKB_CB(skb)->frag_off; |
32 | iph->ttl = XFRM_MODE_SKB_CB(skb)->ttl; |
33 | } |
34 | |
35 | /* Add encapsulation header. |
36 | * |
37 | * The top IP header will be constructed per draft-nikander-esp-beet-mode-06.txt. |
38 | */ |
39 | static int xfrm4_beet_output(struct xfrm_state *x, struct sk_buff *skb) |
40 | { |
41 | struct ip_beet_phdr *ph; |
42 | struct iphdr *top_iph; |
43 | int hdrlen, optlen; |
44 | |
45 | hdrlen = 0; |
46 | optlen = XFRM_MODE_SKB_CB(skb)->optlen; |
47 | if (unlikely(optlen)) |
48 | hdrlen += IPV4_BEET_PHMAXLEN - (optlen & 4); |
49 | |
50 | skb_set_network_header(skb, -x->props.header_len - |
51 | hdrlen + (XFRM_MODE_SKB_CB(skb)->ihl - sizeof(*top_iph))); |
52 | if (x->sel.family != AF_INET6) |
53 | skb->network_header += IPV4_BEET_PHMAXLEN; |
54 | skb->mac_header = skb->network_header + |
55 | offsetof(struct iphdr, protocol); |
56 | skb->transport_header = skb->network_header + sizeof(*top_iph); |
57 | |
58 | xfrm4_beet_make_header(skb); |
59 | |
60 | ph = __skb_pull(skb, XFRM_MODE_SKB_CB(skb)->ihl - hdrlen); |
61 | |
62 | top_iph = ip_hdr(skb); |
63 | |
64 | if (unlikely(optlen)) { |
65 | BUG_ON(optlen < 0); |
66 | |
67 | ph->padlen = 4 - (optlen & 4); |
68 | ph->hdrlen = optlen / 8; |
69 | ph->nexthdr = top_iph->protocol; |
70 | if (ph->padlen) |
71 | memset(ph + 1, IPOPT_NOP, ph->padlen); |
72 | |
73 | top_iph->protocol = IPPROTO_BEETPH; |
74 | top_iph->ihl = sizeof(struct iphdr) / 4; |
75 | } |
76 | |
77 | top_iph->saddr = x->props.saddr.a4; |
78 | top_iph->daddr = x->id.daddr.a4; |
79 | |
80 | return 0; |
81 | } |
82 | |
83 | static int xfrm4_beet_input(struct xfrm_state *x, struct sk_buff *skb) |
84 | { |
85 | struct iphdr *iph; |
86 | int optlen = 0; |
87 | int err = -EINVAL; |
88 | |
89 | if (unlikely(XFRM_MODE_SKB_CB(skb)->protocol == IPPROTO_BEETPH)) { |
90 | struct ip_beet_phdr *ph; |
91 | int phlen; |
92 | |
93 | if (!pskb_may_pull(skb, sizeof(*ph))) |
94 | goto out; |
95 | |
96 | ph = (struct ip_beet_phdr *)skb->data; |
97 | |
98 | phlen = sizeof(*ph) + ph->padlen; |
99 | optlen = ph->hdrlen * 8 + (IPV4_BEET_PHMAXLEN - phlen); |
100 | if (optlen < 0 || optlen & 3 || optlen > 250) |
101 | goto out; |
102 | |
103 | XFRM_MODE_SKB_CB(skb)->protocol = ph->nexthdr; |
104 | |
105 | if (!pskb_may_pull(skb, phlen)) |
106 | goto out; |
107 | __skb_pull(skb, phlen); |
108 | } |
109 | |
110 | skb_push(skb, sizeof(*iph)); |
111 | skb_reset_network_header(skb); |
112 | skb_mac_header_rebuild(skb); |
113 | |
114 | xfrm4_beet_make_header(skb); |
115 | |
116 | iph = ip_hdr(skb); |
117 | |
118 | iph->ihl += optlen / 4; |
119 | iph->tot_len = htons(skb->len); |
120 | iph->daddr = x->sel.daddr.a4; |
121 | iph->saddr = x->sel.saddr.a4; |
122 | iph->check = 0; |
123 | iph->check = ip_fast_csum(skb_network_header(skb), iph->ihl); |
124 | err = 0; |
125 | out: |
126 | return err; |
127 | } |
128 | |
129 | static struct xfrm_mode xfrm4_beet_mode = { |
130 | .input2 = xfrm4_beet_input, |
131 | .input = xfrm_prepare_input, |
132 | .output2 = xfrm4_beet_output, |
133 | .output = xfrm4_prepare_output, |
134 | .owner = THIS_MODULE, |
135 | .encap = XFRM_MODE_BEET, |
136 | .flags = XFRM_MODE_FLAG_TUNNEL, |
137 | }; |
138 | |
139 | static int __init xfrm4_beet_init(void) |
140 | { |
141 | return xfrm_register_mode(&xfrm4_beet_mode, AF_INET); |
142 | } |
143 | |
144 | static void __exit xfrm4_beet_exit(void) |
145 | { |
146 | int err; |
147 | |
148 | err = xfrm_unregister_mode(&xfrm4_beet_mode, AF_INET); |
149 | BUG_ON(err); |
150 | } |
151 | |
152 | module_init(xfrm4_beet_init); |
153 | module_exit(xfrm4_beet_exit); |
154 | MODULE_LICENSE("GPL" ); |
155 | MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_BEET); |
156 | |