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 20static void xfrm4_beet_make_header(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 */ 39static 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 = (struct ip_beet_phdr *) 61 __skb_pull(skb, XFRM_MODE_SKB_CB(skb)->ihl - hdrlen); 62 63 top_iph = ip_hdr(skb); 64 65 if (unlikely(optlen)) { 66 BUG_ON(optlen < 0); 67 68 ph->padlen = 4 - (optlen & 4); 69 ph->hdrlen = optlen / 8; 70 ph->nexthdr = top_iph->protocol; 71 if (ph->padlen) 72 memset(ph + 1, IPOPT_NOP, ph->padlen); 73 74 top_iph->protocol = IPPROTO_BEETPH; 75 top_iph->ihl = sizeof(struct iphdr) / 4; 76 } 77 78 top_iph->saddr = x->props.saddr.a4; 79 top_iph->daddr = x->id.daddr.a4; 80 81 return 0; 82} 83 84static int xfrm4_beet_input(struct xfrm_state *x, struct sk_buff *skb) 85{ 86 struct iphdr *iph; 87 int optlen = 0; 88 int err = -EINVAL; 89 90 if (unlikely(XFRM_MODE_SKB_CB(skb)->protocol == IPPROTO_BEETPH)) { 91 struct ip_beet_phdr *ph; 92 int phlen; 93 94 if (!pskb_may_pull(skb, sizeof(*ph))) 95 goto out; 96 97 ph = (struct ip_beet_phdr *)skb->data; 98 99 phlen = sizeof(*ph) + ph->padlen; 100 optlen = ph->hdrlen * 8 + (IPV4_BEET_PHMAXLEN - phlen); 101 if (optlen < 0 || optlen & 3 || optlen > 250) 102 goto out; 103 104 XFRM_MODE_SKB_CB(skb)->protocol = ph->nexthdr; 105 106 if (!pskb_may_pull(skb, phlen)) 107 goto out; 108 __skb_pull(skb, phlen); 109 } 110 111 skb_push(skb, sizeof(*iph)); 112 skb_reset_network_header(skb); 113 114 memmove(skb->data - skb->mac_len, skb_mac_header(skb), 115 skb->mac_len); 116 skb_set_mac_header(skb, -skb->mac_len); 117 118 xfrm4_beet_make_header(skb); 119 120 iph = ip_hdr(skb); 121 122 iph->ihl += optlen / 4; 123 iph->tot_len = htons(skb->len); 124 iph->daddr = x->sel.daddr.a4; 125 iph->saddr = x->sel.saddr.a4; 126 iph->check = 0; 127 iph->check = ip_fast_csum(skb_network_header(skb), iph->ihl); 128 err = 0; 129out: 130 return err; 131} 132 133static struct xfrm_mode xfrm4_beet_mode = { 134 .input2 = xfrm4_beet_input, 135 .input = xfrm_prepare_input, 136 .output2 = xfrm4_beet_output, 137 .output = xfrm4_prepare_output, 138 .owner = THIS_MODULE, 139 .encap = XFRM_MODE_BEET, 140 .flags = XFRM_MODE_FLAG_TUNNEL, 141}; 142 143static int __init xfrm4_beet_init(void) 144{ 145 return xfrm_register_mode(&xfrm4_beet_mode, AF_INET); 146} 147 148static void __exit xfrm4_beet_exit(void) 149{ 150 int err; 151 152 err = xfrm_unregister_mode(&xfrm4_beet_mode, AF_INET); 153 BUG_ON(err); 154} 155 156module_init(xfrm4_beet_init); 157module_exit(xfrm4_beet_exit); 158MODULE_LICENSE("GPL"); 159MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_BEET); 160