| rjw | 1f88458 | 2022-01-06 17:20:42 +0800 | [diff] [blame^] | 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 | |
| 21 | static int xfrm4_tunnel_check_size(struct sk_buff *skb) |
| 22 | { |
| 23 | int mtu, ret = 0; |
| 24 | |
| 25 | if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE) |
| 26 | goto out; |
| 27 | |
| 28 | if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->ignore_df) |
| 29 | goto out; |
| 30 | |
| 31 | mtu = dst_mtu(skb_dst(skb)); |
| 32 | if ((!skb_is_gso(skb) && skb->len > mtu) || |
| 33 | (skb_is_gso(skb) && skb_gso_network_seglen(skb) > ip_skb_dst_mtu(skb->sk, skb))) { |
| 34 | skb->protocol = htons(ETH_P_IP); |
| 35 | |
| 36 | if (skb->sk) |
| 37 | xfrm_local_error(skb, mtu); |
| 38 | else |
| 39 | icmp_send(skb, ICMP_DEST_UNREACH, |
| 40 | ICMP_FRAG_NEEDED, htonl(mtu)); |
| 41 | ret = -EMSGSIZE; |
| 42 | } |
| 43 | out: |
| 44 | return ret; |
| 45 | } |
| 46 | |
| 47 | int 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 | |
| 60 | int 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 | IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE; |
| 69 | skb->protocol = htons(ETH_P_IP); |
| 70 | |
| 71 | return x->outer_mode->output2(x, skb); |
| 72 | } |
| 73 | EXPORT_SYMBOL(xfrm4_prepare_output); |
| 74 | |
| 75 | int xfrm4_output_finish(struct sock *sk, struct sk_buff *skb) |
| 76 | { |
| 77 | memset(IPCB(skb), 0, sizeof(*IPCB(skb))); |
| 78 | |
| 79 | IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED; |
| 80 | |
| 81 | return xfrm_output(sk, skb); |
| 82 | } |
| 83 | |
| 84 | static int __xfrm4_output(struct net *net, struct sock *sk, struct sk_buff *skb) |
| 85 | { |
| 86 | struct xfrm_state *x = skb_dst(skb)->xfrm; |
| 87 | |
| 88 | #ifdef CONFIG_NETFILTER |
| 89 | if (!x) { |
| 90 | IPCB(skb)->flags |= IPSKB_REROUTED; |
| 91 | return dst_output(net, sk, skb); |
| 92 | } |
| 93 | #endif |
| 94 | |
| 95 | return x->outer_mode->afinfo->output_finish(sk, skb); |
| 96 | } |
| 97 | |
| 98 | int xfrm4_output(struct net *net, struct sock *sk, struct sk_buff *skb) |
| 99 | { |
| 100 | return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, |
| 101 | net, sk, skb, NULL, skb_dst(skb)->dev, |
| 102 | __xfrm4_output, |
| 103 | !(IPCB(skb)->flags & IPSKB_REROUTED)); |
| 104 | } |
| 105 | |
| 106 | void xfrm4_local_error(struct sk_buff *skb, u32 mtu) |
| 107 | { |
| 108 | struct iphdr *hdr; |
| 109 | |
| 110 | hdr = skb->encapsulation ? inner_ip_hdr(skb) : ip_hdr(skb); |
| 111 | ip_local_error(skb->sk, EMSGSIZE, hdr->daddr, |
| 112 | inet_sk(skb->sk)->inet_dport, mtu); |
| 113 | } |