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 */ |
20 | int 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 | struct flow_keys flkeys; |
29 | unsigned int hh_len; |
30 | |
31 | sk = sk_to_full_sk(sk); |
32 | flags = sk ? inet_sk_flowi_flags(sk) : 0; |
33 | |
34 | if (addr_type == RTN_UNSPEC) |
35 | addr_type = inet_addr_type_dev_table(net, dev, addr: saddr); |
36 | if (addr_type == RTN_LOCAL || addr_type == RTN_UNICAST) |
37 | flags |= FLOWI_FLAG_ANYSRC; |
38 | else |
39 | saddr = 0; |
40 | |
41 | /* some non-standard hacks like ipt_REJECT.c:send_reset() can cause |
42 | * packets with foreign saddr to appear on the NF_INET_LOCAL_OUT hook. |
43 | */ |
44 | fl4.daddr = iph->daddr; |
45 | fl4.saddr = saddr; |
46 | fl4.flowi4_tos = RT_TOS(iph->tos); |
47 | fl4.flowi4_oif = sk ? sk->sk_bound_dev_if : 0; |
48 | fl4.flowi4_l3mdev = l3mdev_master_ifindex(dev); |
49 | fl4.flowi4_mark = skb->mark; |
50 | fl4.flowi4_flags = flags; |
51 | fib4_rules_early_flow_dissect(net, skb, fl4: &fl4, flkeys: &flkeys); |
52 | rt = ip_route_output_key(net, flp: &fl4); |
53 | if (IS_ERR(ptr: rt)) |
54 | return PTR_ERR(ptr: rt); |
55 | |
56 | /* Drop old route. */ |
57 | skb_dst_drop(skb); |
58 | skb_dst_set(skb, dst: &rt->dst); |
59 | |
60 | if (skb_dst(skb)->error) |
61 | return skb_dst(skb)->error; |
62 | |
63 | #ifdef CONFIG_XFRM |
64 | if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) && |
65 | xfrm_decode_session(net, skb, fl: flowi4_to_flowi(fl4: &fl4), AF_INET) == 0) { |
66 | struct dst_entry *dst = skb_dst(skb); |
67 | skb_dst_set(skb, NULL); |
68 | dst = xfrm_lookup(net, dst_orig: dst, fl: flowi4_to_flowi(fl4: &fl4), sk, flags: 0); |
69 | if (IS_ERR(ptr: dst)) |
70 | return PTR_ERR(ptr: dst); |
71 | skb_dst_set(skb, dst); |
72 | } |
73 | #endif |
74 | |
75 | /* Change in oif may mean change in hh_len. */ |
76 | hh_len = skb_dst(skb)->dev->hard_header_len; |
77 | if (skb_headroom(skb) < hh_len && |
78 | pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)), |
79 | ntail: 0, GFP_ATOMIC)) |
80 | return -ENOMEM; |
81 | |
82 | return 0; |
83 | } |
84 | EXPORT_SYMBOL(ip_route_me_harder); |
85 | |
86 | int nf_ip_route(struct net *net, struct dst_entry **dst, struct flowi *fl, |
87 | bool strict __always_unused) |
88 | { |
89 | struct rtable *rt = ip_route_output_key(net, flp: &fl->u.ip4); |
90 | if (IS_ERR(ptr: rt)) |
91 | return PTR_ERR(ptr: rt); |
92 | *dst = &rt->dst; |
93 | return 0; |
94 | } |
95 | EXPORT_SYMBOL_GPL(nf_ip_route); |
96 | |