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
19void 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: &fl6, mtu);
28}
29
30void 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: &fl6, info: mtu);
41}
42
43static int __xfrm6_output_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
44{
45 return xfrm_output(sk, skb);
46}
47
48static 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
61static 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(dst: skb_dst(skb));
82
83 toobig = skb->len > mtu && !skb_is_gso(skb);
84
85 if (toobig && xfrm6_local_dontfrag(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 && sk) {
93 xfrm_local_error(skb, mtu);
94 kfree_skb(skb);
95 return -EMSGSIZE;
96 }
97
98 if (toobig)
99 return ip6_fragment(net, sk, skb,
100 output: __xfrm6_output_finish);
101
102skip_frag:
103 return xfrm_output(sk, skb);
104}
105
106int xfrm6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
107{
108 return NF_HOOK_COND(pf: NFPROTO_IPV6, hook: NF_INET_POST_ROUTING,
109 net, sk, skb, in: skb->dev, out: skb_dst_dev(skb),
110 okfn: __xfrm6_output,
111 cond: !(IP6CB(skb)->flags & IP6SKB_REROUTED));
112}
113