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 void xfrm6_local_rxpmtu(struct sk_buff *skb, u32 mtu) 20 { 21 struct flowi6 fl6; 22 struct sock *sk = skb->sk; 23 24 fl6.flowi6_oif = sk->sk_bound_dev_if; 25 fl6.daddr = ipv6_hdr(skb)->daddr; 26 27 ipv6_local_rxpmtu(sk, &fl6, mtu); 28 } 29 30 void xfrm6_local_error(struct sk_buff *skb, u32 mtu) 31 { 32 struct flowi6 fl6; 33 const struct ipv6hdr *hdr; 34 struct sock *sk = skb->sk; 35 36 hdr = skb->encapsulation ? inner_ipv6_hdr(skb) : ipv6_hdr(skb); 37 fl6.fl6_dport = inet_sk(sk)->inet_dport; 38 fl6.daddr = hdr->daddr; 39 40 ipv6_local_error(sk, EMSGSIZE, &fl6, mtu); 41 } 42 43 static int __xfrm6_output_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 44 { 45 return xfrm_output(sk, skb); 46 } 47 48 static int xfrm6_noneed_fragment(struct sk_buff *skb) 49 { 50 struct frag_hdr *fh; 51 u8 prevhdr = ipv6_hdr(skb)->nexthdr; 52 53 if (prevhdr != NEXTHDR_FRAGMENT) 54 return 0; 55 fh = (struct frag_hdr *)(skb->data + sizeof(struct ipv6hdr)); 56 if (fh->nexthdr == NEXTHDR_ESP || fh->nexthdr == NEXTHDR_AUTH) 57 return 1; 58 return 0; 59 } 60 61 static int __xfrm6_output(struct net *net, struct sock *sk, struct sk_buff *skb) 62 { 63 struct dst_entry *dst = skb_dst(skb); 64 struct xfrm_state *x = dst->xfrm; 65 unsigned int mtu; 66 bool toobig; 67 68 #ifdef CONFIG_NETFILTER 69 if (!x) { 70 IP6CB(skb)->flags |= IP6SKB_REROUTED; 71 return dst_output(net, sk, skb); 72 } 73 #endif 74 75 if (x->props.mode != XFRM_MODE_TUNNEL) 76 goto skip_frag; 77 78 if (skb->protocol == htons(ETH_P_IPV6)) 79 mtu = ip6_skb_dst_mtu(skb); 80 else 81 mtu = dst_mtu(skb_dst(skb)); 82 83 toobig = skb->len > mtu && !skb_is_gso(skb); 84 85 if (toobig && xfrm6_local_dontfrag(skb->sk)) { 86 xfrm6_local_rxpmtu(skb, mtu); 87 kfree_skb(skb); 88 return -EMSGSIZE; 89 } else if (toobig && xfrm6_noneed_fragment(skb)) { 90 skb->ignore_df = 1; 91 goto skip_frag; 92 } else if (!skb->ignore_df && toobig && skb->sk) { 93 xfrm_local_error(skb, mtu); 94 kfree_skb(skb); 95 return -EMSGSIZE; 96 } 97 98 if (toobig || dst_allfrag(skb_dst(skb))) 99 return ip6_fragment(net, sk, skb, 100 __xfrm6_output_finish); 101 102 skip_frag: 103 return xfrm_output(sk, skb); 104 } 105 106 int xfrm6_output(struct net *net, struct sock *sk, struct sk_buff *skb) 107 { 108 return NF_HOOK_COND(NFPROTO_IPV6, NF_INET_POST_ROUTING, 109 net, sk, skb, skb->dev, skb_dst(skb)->dev, 110 __xfrm6_output, 111 !(IP6CB(skb)->flags & IP6SKB_REROUTED)); 112 } 113