1 /* 2 * xfrm6_output.c - Common IPsec encapsulation code for IPv6. 3 * Copyright (C) 2002 USAGI/WIDE Project 4 * Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au> 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License 8 * as published by the Free Software Foundation; either version 9 * 2 of the License, or (at your option) any later version. 10 */ 11 12 #include <linux/if_ether.h> 13 #include <linux/kernel.h> 14 #include <linux/module.h> 15 #include <linux/skbuff.h> 16 #include <linux/icmpv6.h> 17 #include <linux/netfilter_ipv6.h> 18 #include <net/dst.h> 19 #include <net/ipv6.h> 20 #include <net/ip6_route.h> 21 #include <net/xfrm.h> 22 23 int xfrm6_find_1stfragopt(struct xfrm_state *x, struct sk_buff *skb, 24 u8 **prevhdr) 25 { 26 return ip6_find_1stfragopt(skb, prevhdr); 27 } 28 EXPORT_SYMBOL(xfrm6_find_1stfragopt); 29 30 static int xfrm6_local_dontfrag(struct sk_buff *skb) 31 { 32 int proto; 33 struct sock *sk = skb->sk; 34 35 if (sk) { 36 if (sk->sk_family != AF_INET6) 37 return 0; 38 39 proto = sk->sk_protocol; 40 if (proto == IPPROTO_UDP || proto == IPPROTO_RAW) 41 return inet6_sk(sk)->dontfrag; 42 } 43 44 return 0; 45 } 46 47 static void xfrm6_local_rxpmtu(struct sk_buff *skb, u32 mtu) 48 { 49 struct flowi6 fl6; 50 struct sock *sk = skb->sk; 51 52 fl6.flowi6_oif = sk->sk_bound_dev_if; 53 fl6.daddr = ipv6_hdr(skb)->daddr; 54 55 ipv6_local_rxpmtu(sk, &fl6, mtu); 56 } 57 58 void xfrm6_local_error(struct sk_buff *skb, u32 mtu) 59 { 60 struct flowi6 fl6; 61 const struct ipv6hdr *hdr; 62 struct sock *sk = skb->sk; 63 64 hdr = skb->encapsulation ? inner_ipv6_hdr(skb) : ipv6_hdr(skb); 65 fl6.fl6_dport = inet_sk(sk)->inet_dport; 66 fl6.daddr = hdr->daddr; 67 68 ipv6_local_error(sk, EMSGSIZE, &fl6, mtu); 69 } 70 71 static int xfrm6_tunnel_check_size(struct sk_buff *skb) 72 { 73 int mtu, ret = 0; 74 struct dst_entry *dst = skb_dst(skb); 75 76 mtu = dst_mtu(dst); 77 if (mtu < IPV6_MIN_MTU) 78 mtu = IPV6_MIN_MTU; 79 80 if (!skb->ignore_df && skb->len > mtu) { 81 skb->dev = dst->dev; 82 skb->protocol = htons(ETH_P_IPV6); 83 84 if (xfrm6_local_dontfrag(skb)) 85 xfrm6_local_rxpmtu(skb, mtu); 86 else if (skb->sk) 87 xfrm_local_error(skb, mtu); 88 else 89 icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu); 90 ret = -EMSGSIZE; 91 } 92 93 return ret; 94 } 95 96 int xfrm6_extract_output(struct xfrm_state *x, struct sk_buff *skb) 97 { 98 int err; 99 100 err = xfrm6_tunnel_check_size(skb); 101 if (err) 102 return err; 103 104 XFRM_MODE_SKB_CB(skb)->protocol = ipv6_hdr(skb)->nexthdr; 105 106 return xfrm6_extract_header(skb); 107 } 108 109 int xfrm6_prepare_output(struct xfrm_state *x, struct sk_buff *skb) 110 { 111 int err; 112 113 err = xfrm_inner_extract_output(x, skb); 114 if (err) 115 return err; 116 117 skb->ignore_df = 1; 118 skb->protocol = htons(ETH_P_IPV6); 119 120 return x->outer_mode->output2(x, skb); 121 } 122 EXPORT_SYMBOL(xfrm6_prepare_output); 123 124 int xfrm6_output_finish(struct sock *sk, struct sk_buff *skb) 125 { 126 memset(IP6CB(skb), 0, sizeof(*IP6CB(skb))); 127 128 #ifdef CONFIG_NETFILTER 129 IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED; 130 #endif 131 132 return xfrm_output(sk, skb); 133 } 134 135 static int __xfrm6_output_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 136 { 137 struct xfrm_state *x = skb_dst(skb)->xfrm; 138 139 return x->outer_mode->afinfo->output_finish(sk, skb); 140 } 141 142 static int __xfrm6_output(struct net *net, struct sock *sk, struct sk_buff *skb) 143 { 144 struct dst_entry *dst = skb_dst(skb); 145 struct xfrm_state *x = dst->xfrm; 146 int mtu; 147 bool toobig; 148 149 #ifdef CONFIG_NETFILTER 150 if (!x) { 151 IP6CB(skb)->flags |= IP6SKB_REROUTED; 152 return dst_output(net, sk, skb); 153 } 154 #endif 155 156 if (x->props.mode != XFRM_MODE_TUNNEL) 157 goto skip_frag; 158 159 if (skb->protocol == htons(ETH_P_IPV6)) 160 mtu = ip6_skb_dst_mtu(skb); 161 else 162 mtu = dst_mtu(skb_dst(skb)); 163 164 toobig = skb->len > mtu && !skb_is_gso(skb); 165 166 if (toobig && xfrm6_local_dontfrag(skb)) { 167 xfrm6_local_rxpmtu(skb, mtu); 168 return -EMSGSIZE; 169 } else if (!skb->ignore_df && toobig && skb->sk) { 170 xfrm_local_error(skb, mtu); 171 return -EMSGSIZE; 172 } 173 174 if (toobig || dst_allfrag(skb_dst(skb))) 175 return ip6_fragment(net, sk, skb, 176 __xfrm6_output_finish); 177 178 skip_frag: 179 return x->outer_mode->afinfo->output_finish(sk, skb); 180 } 181 182 int xfrm6_output(struct net *net, struct sock *sk, struct sk_buff *skb) 183 { 184 return NF_HOOK_COND(NFPROTO_IPV6, NF_INET_POST_ROUTING, 185 net, sk, skb, NULL, skb_dst(skb)->dev, 186 __xfrm6_output, 187 !(IP6CB(skb)->flags & IP6SKB_REROUTED)); 188 } 189