net/ipv6/xfrm6_output.c

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