1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * xfrm6_output.c - Common IPsec encapsulation code for IPv6. 4 * Copyright (C) 2002 USAGI/WIDE Project 5 * Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au> 6 */ 7 8 #include <linux/if_ether.h> 9 #include <linux/kernel.h> 10 #include <linux/module.h> 11 #include <linux/skbuff.h> 12 #include <linux/icmpv6.h> 13 #include <linux/netfilter_ipv6.h> 14 #include <net/dst.h> 15 #include <net/ipv6.h> 16 #include <net/ip6_route.h> 17 #include <net/xfrm.h> 18 19 int xfrm6_find_1stfragopt(struct xfrm_state *x, struct sk_buff *skb, 20 u8 **prevhdr) 21 { 22 return ip6_find_1stfragopt(skb, prevhdr); 23 } 24 EXPORT_SYMBOL(xfrm6_find_1stfragopt); 25 26 static int xfrm6_local_dontfrag(struct sk_buff *skb) 27 { 28 int proto; 29 struct sock *sk = skb->sk; 30 31 if (sk) { 32 if (sk->sk_family != AF_INET6) 33 return 0; 34 35 proto = sk->sk_protocol; 36 if (proto == IPPROTO_UDP || proto == IPPROTO_RAW) 37 return inet6_sk(sk)->dontfrag; 38 } 39 40 return 0; 41 } 42 43 static void xfrm6_local_rxpmtu(struct sk_buff *skb, u32 mtu) 44 { 45 struct flowi6 fl6; 46 struct sock *sk = skb->sk; 47 48 fl6.flowi6_oif = sk->sk_bound_dev_if; 49 fl6.daddr = ipv6_hdr(skb)->daddr; 50 51 ipv6_local_rxpmtu(sk, &fl6, mtu); 52 } 53 54 void xfrm6_local_error(struct sk_buff *skb, u32 mtu) 55 { 56 struct flowi6 fl6; 57 const struct ipv6hdr *hdr; 58 struct sock *sk = skb->sk; 59 60 hdr = skb->encapsulation ? inner_ipv6_hdr(skb) : ipv6_hdr(skb); 61 fl6.fl6_dport = inet_sk(sk)->inet_dport; 62 fl6.daddr = hdr->daddr; 63 64 ipv6_local_error(sk, EMSGSIZE, &fl6, mtu); 65 } 66 67 static int xfrm6_tunnel_check_size(struct sk_buff *skb) 68 { 69 int mtu, ret = 0; 70 struct dst_entry *dst = skb_dst(skb); 71 72 if (skb->ignore_df) 73 goto out; 74 75 mtu = dst_mtu(dst); 76 if (mtu < IPV6_MIN_MTU) 77 mtu = IPV6_MIN_MTU; 78 79 if ((!skb_is_gso(skb) && skb->len > mtu) || 80 (skb_is_gso(skb) && 81 !skb_gso_validate_network_len(skb, ip6_skb_dst_mtu(skb)))) { 82 skb->dev = dst->dev; 83 skb->protocol = htons(ETH_P_IPV6); 84 85 if (xfrm6_local_dontfrag(skb)) 86 xfrm6_local_rxpmtu(skb, mtu); 87 else if (skb->sk) 88 xfrm_local_error(skb, mtu); 89 else 90 icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu); 91 ret = -EMSGSIZE; 92 } 93 out: 94 return ret; 95 } 96 97 int xfrm6_extract_output(struct xfrm_state *x, struct sk_buff *skb) 98 { 99 int err; 100 101 err = xfrm6_tunnel_check_size(skb); 102 if (err) 103 return err; 104 105 XFRM_MODE_SKB_CB(skb)->protocol = ipv6_hdr(skb)->nexthdr; 106 107 return xfrm6_extract_header(skb); 108 } 109 110 int xfrm6_output_finish(struct sock *sk, struct sk_buff *skb) 111 { 112 memset(IP6CB(skb), 0, sizeof(*IP6CB(skb))); 113 114 #ifdef CONFIG_NETFILTER 115 IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED; 116 #endif 117 118 return xfrm_output(sk, skb); 119 } 120 121 static int __xfrm6_output_state_finish(struct xfrm_state *x, struct sock *sk, 122 struct sk_buff *skb) 123 { 124 const struct xfrm_state_afinfo *afinfo; 125 int ret = -EAFNOSUPPORT; 126 127 rcu_read_lock(); 128 afinfo = xfrm_state_afinfo_get_rcu(x->outer_mode.family); 129 if (likely(afinfo)) 130 ret = afinfo->output_finish(sk, skb); 131 else 132 kfree_skb(skb); 133 rcu_read_unlock(); 134 135 return ret; 136 } 137 138 static int __xfrm6_output_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 139 { 140 struct xfrm_state *x = skb_dst(skb)->xfrm; 141 142 return __xfrm6_output_state_finish(x, sk, skb); 143 } 144 145 static int __xfrm6_output(struct net *net, struct sock *sk, struct sk_buff *skb) 146 { 147 struct dst_entry *dst = skb_dst(skb); 148 struct xfrm_state *x = dst->xfrm; 149 int mtu; 150 bool toobig; 151 152 #ifdef CONFIG_NETFILTER 153 if (!x) { 154 IP6CB(skb)->flags |= IP6SKB_REROUTED; 155 return dst_output(net, sk, skb); 156 } 157 #endif 158 159 if (x->props.mode != XFRM_MODE_TUNNEL) 160 goto skip_frag; 161 162 if (skb->protocol == htons(ETH_P_IPV6)) 163 mtu = ip6_skb_dst_mtu(skb); 164 else 165 mtu = dst_mtu(skb_dst(skb)); 166 167 toobig = skb->len > mtu && !skb_is_gso(skb); 168 169 if (toobig && xfrm6_local_dontfrag(skb)) { 170 xfrm6_local_rxpmtu(skb, mtu); 171 kfree_skb(skb); 172 return -EMSGSIZE; 173 } else if (!skb->ignore_df && toobig && skb->sk) { 174 xfrm_local_error(skb, mtu); 175 kfree_skb(skb); 176 return -EMSGSIZE; 177 } 178 179 if (toobig || dst_allfrag(skb_dst(skb))) 180 return ip6_fragment(net, sk, skb, 181 __xfrm6_output_finish); 182 183 skip_frag: 184 return __xfrm6_output_state_finish(x, sk, skb); 185 } 186 187 int xfrm6_output(struct net *net, struct sock *sk, struct sk_buff *skb) 188 { 189 return NF_HOOK_COND(NFPROTO_IPV6, NF_INET_POST_ROUTING, 190 net, sk, skb, skb->dev, skb_dst(skb)->dev, 191 __xfrm6_output, 192 !(IP6CB(skb)->flags & IP6SKB_REROUTED)); 193 } 194