tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * IPv4 specific functions of netfilter core
3 *
4 * Rusty Russell (C) 2000 -- This code is GPL.
5 * Patrick McHardy (C) 2006-2012
6 */
7#include <linux/kernel.h>
8#include <linux/netfilter.h>
9#include <linux/netfilter_ipv4.h>
10#include <linux/ip.h>
11#include <linux/skbuff.h>
12#include <linux/gfp.h>
13#include <linux/export.h>
14#include <net/route.h>
15#include <net/xfrm.h>
16#include <net/ip.h>
17#include <net/netfilter/nf_queue.h>
18
19/* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */
20int ip_route_me_harder(struct net *net, struct sock *sk, struct sk_buff *skb, unsigned int addr_type)
21{
22 const struct iphdr *iph = ip_hdr(skb);
23 struct rtable *rt;
24 struct flowi4 fl4 = {};
25 __be32 saddr = iph->saddr;
26 __u8 flags;
27 struct net_device *dev = skb_dst(skb)->dev;
28 unsigned int hh_len;
29
30 sk = sk_to_full_sk(sk);
31 flags = sk ? inet_sk_flowi_flags(sk) : 0;
32
33 if (addr_type == RTN_UNSPEC)
34 addr_type = inet_addr_type_dev_table(net, dev, saddr);
35 if (addr_type == RTN_LOCAL || addr_type == RTN_UNICAST)
36 flags |= FLOWI_FLAG_ANYSRC;
37 else
38 saddr = 0;
39
40 /* some non-standard hacks like ipt_REJECT.c:send_reset() can cause
41 * packets with foreign saddr to appear on the NF_INET_LOCAL_OUT hook.
42 */
43 fl4.daddr = iph->daddr;
44 fl4.saddr = saddr;
45 fl4.flowi4_tos = RT_TOS(iph->tos);
46 fl4.flowi4_oif = sk ? sk->sk_bound_dev_if : 0;
47 if (!fl4.flowi4_oif)
48 fl4.flowi4_oif = l3mdev_master_ifindex(dev);
49 fl4.flowi4_mark = skb->mark;
50 fl4.flowi4_flags = flags;
51 rt = ip_route_output_key(net, &fl4);
52 if (IS_ERR(rt))
53 return PTR_ERR(rt);
54
55 /* Drop old route. */
56 skb_dst_drop(skb);
57 skb_dst_set(skb, &rt->dst);
58
59 if (skb_dst(skb)->error)
60 return skb_dst(skb)->error;
61
62#ifdef CONFIG_XFRM
63 if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
64 xfrm_decode_session(skb, flowi4_to_flowi(&fl4), AF_INET) == 0) {
65 struct dst_entry *dst = skb_dst(skb);
66 skb_dst_set(skb, NULL);
67 dst = xfrm_lookup(net, dst, flowi4_to_flowi(&fl4), sk, 0);
68 if (IS_ERR(dst))
69 return PTR_ERR(dst);
70 skb_dst_set(skb, dst);
71 }
72#endif
73
74 /* Change in oif may mean change in hh_len. */
75 hh_len = skb_dst(skb)->dev->hard_header_len;
76 if (skb_headroom(skb) < hh_len &&
77 pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)),
78 0, GFP_ATOMIC))
79 return -ENOMEM;
80
81 return 0;
82}
83EXPORT_SYMBOL(ip_route_me_harder);
84
85int nf_ip_route(struct net *net, struct dst_entry **dst, struct flowi *fl,
86 bool strict __always_unused)
87{
88 struct rtable *rt = ip_route_output_key(net, &fl->u.ip4);
89 if (IS_ERR(rt))
90 return PTR_ERR(rt);
91 *dst = &rt->dst;
92 return 0;
93}
94EXPORT_SYMBOL_GPL(nf_ip_route);