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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * xfrm4_output.c - Common IPsec encapsulation code for IPv4.
4 * Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au>
5 */
6
7#include <linux/if_ether.h>
8#include <linux/kernel.h>
9#include <linux/module.h>
10#include <linux/skbuff.h>
11#include <linux/netfilter_ipv4.h>
12#include <net/dst.h>
13#include <net/ip.h>
14#include <net/xfrm.h>
15#include <net/icmp.h>
16
17static int xfrm4_tunnel_check_size(struct sk_buff *skb)
18{
19 int mtu, ret = 0;
20
21 if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE)
22 goto out;
23
24 if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->ignore_df)
25 goto out;
26
27 mtu = dst_mtu(skb_dst(skb));
28 if ((!skb_is_gso(skb) && skb->len > mtu) ||
29 (skb_is_gso(skb) &&
30 !skb_gso_validate_network_len(skb, ip_skb_dst_mtu(skb->sk, skb)))) {
31 skb->protocol = htons(ETH_P_IP);
32
33 if (skb->sk)
34 xfrm_local_error(skb, mtu);
35 else
36 icmp_send(skb, ICMP_DEST_UNREACH,
37 ICMP_FRAG_NEEDED, htonl(mtu));
38 ret = -EMSGSIZE;
39 }
40out:
41 return ret;
42}
43
44int xfrm4_extract_output(struct xfrm_state *x, struct sk_buff *skb)
45{
46 int err;
47
48 err = xfrm4_tunnel_check_size(skb);
49 if (err)
50 return err;
51
52 XFRM_MODE_SKB_CB(skb)->protocol = ip_hdr(skb)->protocol;
53
54 return xfrm4_extract_header(skb);
55}
56
57int xfrm4_output_finish(struct sock *sk, struct sk_buff *skb)
58{
59 memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
60
61#ifdef CONFIG_NETFILTER
62 IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED;
63#endif
64
65 return xfrm_output(sk, skb);
66}
67
68static int __xfrm4_output(struct net *net, struct sock *sk, struct sk_buff *skb)
69{
70 struct xfrm_state *x = skb_dst(skb)->xfrm;
71 const struct xfrm_state_afinfo *afinfo;
72 int ret = -EAFNOSUPPORT;
73
74#ifdef CONFIG_NETFILTER
75 if (!x) {
76 IPCB(skb)->flags |= IPSKB_REROUTED;
77 return dst_output(net, sk, skb);
78 }
79#endif
80
81 rcu_read_lock();
82 afinfo = xfrm_state_afinfo_get_rcu(x->outer_mode.family);
83 if (likely(afinfo))
84 ret = afinfo->output_finish(sk, skb);
85 else
86 kfree_skb(skb);
87 rcu_read_unlock();
88
89 return ret;
90}
91
92int xfrm4_output(struct net *net, struct sock *sk, struct sk_buff *skb)
93{
94 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
95 net, sk, skb, NULL, skb_dst(skb)->dev,
96 __xfrm4_output,
97 !(IPCB(skb)->flags & IPSKB_REROUTED));
98}
99
100void xfrm4_local_error(struct sk_buff *skb, u32 mtu)
101{
102 struct iphdr *hdr;
103
104 hdr = skb->encapsulation ? inner_ip_hdr(skb) : ip_hdr(skb);
105 ip_local_error(skb->sk, EMSGSIZE, hdr->daddr,
106 inet_sk(skb->sk)->inet_dport, mtu);
107}
1/*
2 * xfrm4_output.c - Common IPsec encapsulation code for IPv4.
3 * Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au>
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License
7 * as published by the Free Software Foundation; either version
8 * 2 of the License, or (at your option) any later version.
9 */
10
11#include <linux/if_ether.h>
12#include <linux/kernel.h>
13#include <linux/module.h>
14#include <linux/skbuff.h>
15#include <linux/netfilter_ipv4.h>
16#include <net/dst.h>
17#include <net/ip.h>
18#include <net/xfrm.h>
19#include <net/icmp.h>
20
21static int xfrm4_tunnel_check_size(struct sk_buff *skb)
22{
23 int mtu, ret = 0;
24 struct dst_entry *dst;
25
26 if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE)
27 goto out;
28
29 if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->local_df)
30 goto out;
31
32 dst = skb_dst(skb);
33 mtu = dst_mtu(dst);
34 if (skb->len > mtu) {
35 if (skb->sk)
36 ip_local_error(skb->sk, EMSGSIZE, ip_hdr(skb)->daddr,
37 inet_sk(skb->sk)->inet_dport, mtu);
38 else
39 icmp_send(skb, ICMP_DEST_UNREACH,
40 ICMP_FRAG_NEEDED, htonl(mtu));
41 ret = -EMSGSIZE;
42 }
43out:
44 return ret;
45}
46
47int xfrm4_extract_output(struct xfrm_state *x, struct sk_buff *skb)
48{
49 int err;
50
51 err = xfrm4_tunnel_check_size(skb);
52 if (err)
53 return err;
54
55 XFRM_MODE_SKB_CB(skb)->protocol = ip_hdr(skb)->protocol;
56
57 return xfrm4_extract_header(skb);
58}
59
60int xfrm4_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
61{
62 int err;
63
64 err = xfrm_inner_extract_output(x, skb);
65 if (err)
66 return err;
67
68 memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
69 IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED;
70
71 skb->protocol = htons(ETH_P_IP);
72
73 return x->outer_mode->output2(x, skb);
74}
75EXPORT_SYMBOL(xfrm4_prepare_output);
76
77int xfrm4_output_finish(struct sk_buff *skb)
78{
79#ifdef CONFIG_NETFILTER
80 if (!skb_dst(skb)->xfrm) {
81 IPCB(skb)->flags |= IPSKB_REROUTED;
82 return dst_output(skb);
83 }
84
85 IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED;
86#endif
87
88 skb->protocol = htons(ETH_P_IP);
89 return xfrm_output(skb);
90}
91
92int xfrm4_output(struct sk_buff *skb)
93{
94 struct dst_entry *dst = skb_dst(skb);
95 struct xfrm_state *x = dst->xfrm;
96
97 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb,
98 NULL, dst->dev,
99 x->outer_mode->afinfo->output_finish,
100 !(IPCB(skb)->flags & IPSKB_REROUTED));
101}