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: &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: &fl6, info: 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(dst: skb_dst(skb)); |
82 | |
83 | toobig = skb->len > mtu && !skb_is_gso(skb); |
84 | |
85 | if (toobig && xfrm6_local_dontfrag(sk: 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) |
99 | return ip6_fragment(net, sk, skb, |
100 | output: __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(pf: NFPROTO_IPV6, hook: NF_INET_POST_ROUTING, |
109 | net, sk, skb, in: skb->dev, out: skb_dst(skb)->dev, |
110 | okfn: __xfrm6_output, |
111 | cond: !(IP6CB(skb)->flags & IP6SKB_REROUTED)); |
112 | } |
113 | |