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 if (skb->ignore_df) 77 goto out; 78 79 mtu = dst_mtu(dst); 80 if (mtu < IPV6_MIN_MTU) 81 mtu = IPV6_MIN_MTU; 82 83 if ((!skb_is_gso(skb) && skb->len > mtu) || 84 (skb_is_gso(skb) && 85 !skb_gso_validate_network_len(skb, ip6_skb_dst_mtu(skb)))) { 86 skb->dev = dst->dev; 87 skb->protocol = htons(ETH_P_IPV6); 88 89 if (xfrm6_local_dontfrag(skb)) 90 xfrm6_local_rxpmtu(skb, mtu); 91 else if (skb->sk) 92 xfrm_local_error(skb, mtu); 93 else 94 icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu); 95 ret = -EMSGSIZE; 96 } 97 out: 98 return ret; 99 } 100 101 int xfrm6_extract_output(struct xfrm_state *x, struct sk_buff *skb) 102 { 103 int err; 104 105 err = xfrm6_tunnel_check_size(skb); 106 if (err) 107 return err; 108 109 XFRM_MODE_SKB_CB(skb)->protocol = ipv6_hdr(skb)->nexthdr; 110 111 return xfrm6_extract_header(skb); 112 } 113 114 int xfrm6_output_finish(struct sock *sk, struct sk_buff *skb) 115 { 116 memset(IP6CB(skb), 0, sizeof(*IP6CB(skb))); 117 118 #ifdef CONFIG_NETFILTER 119 IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED; 120 #endif 121 122 return xfrm_output(sk, skb); 123 } 124 125 static int __xfrm6_output_state_finish(struct xfrm_state *x, struct sock *sk, 126 struct sk_buff *skb) 127 { 128 const struct xfrm_state_afinfo *afinfo; 129 int ret = -EAFNOSUPPORT; 130 131 rcu_read_lock(); 132 afinfo = xfrm_state_afinfo_get_rcu(x->outer_mode.family); 133 if (likely(afinfo)) 134 ret = afinfo->output_finish(sk, skb); 135 else 136 kfree_skb(skb); 137 rcu_read_unlock(); 138 139 return ret; 140 } 141 142 static int __xfrm6_output_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 143 { 144 struct xfrm_state *x = skb_dst(skb)->xfrm; 145 146 return __xfrm6_output_state_finish(x, sk, skb); 147 } 148 149 static int __xfrm6_output(struct net *net, struct sock *sk, struct sk_buff *skb) 150 { 151 struct dst_entry *dst = skb_dst(skb); 152 struct xfrm_state *x = dst->xfrm; 153 int mtu; 154 bool toobig; 155 156 #ifdef CONFIG_NETFILTER 157 if (!x) { 158 IP6CB(skb)->flags |= IP6SKB_REROUTED; 159 return dst_output(net, sk, skb); 160 } 161 #endif 162 163 if (x->props.mode != XFRM_MODE_TUNNEL) 164 goto skip_frag; 165 166 if (skb->protocol == htons(ETH_P_IPV6)) 167 mtu = ip6_skb_dst_mtu(skb); 168 else 169 mtu = dst_mtu(skb_dst(skb)); 170 171 toobig = skb->len > mtu && !skb_is_gso(skb); 172 173 if (toobig && xfrm6_local_dontfrag(skb)) { 174 xfrm6_local_rxpmtu(skb, mtu); 175 kfree_skb(skb); 176 return -EMSGSIZE; 177 } else if (!skb->ignore_df && toobig && skb->sk) { 178 xfrm_local_error(skb, mtu); 179 kfree_skb(skb); 180 return -EMSGSIZE; 181 } 182 183 if (toobig || dst_allfrag(skb_dst(skb))) 184 return ip6_fragment(net, sk, skb, 185 __xfrm6_output_finish); 186 187 skip_frag: 188 return __xfrm6_output_state_finish(x, sk, skb); 189 } 190 191 int xfrm6_output(struct net *net, struct sock *sk, struct sk_buff *skb) 192 { 193 return NF_HOOK_COND(NFPROTO_IPV6, NF_INET_POST_ROUTING, 194 net, sk, skb, NULL, skb_dst(skb)->dev, 195 __xfrm6_output, 196 !(IP6CB(skb)->flags & IP6SKB_REROUTED)); 197 } 198