LXR linux/net/ipv4/xfrm4

   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}
 108