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1 | /* |
2 | * broadcast connection tracking helper | |
3 | * | |
4 | * (c) 2005 Patrick McHardy <kaber@trash.net> | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public License | |
8 | * as published by the Free Software Foundation; either version | |
9 | * 2 of the License, or (at your option) any later version. | |
10 | */ | |
11 | ||
12 | #include <linux/module.h> | |
13 | #include <linux/ip.h> | |
14 | #include <net/route.h> | |
15 | #include <linux/inetdevice.h> | |
16 | #include <linux/skbuff.h> | |
17 | ||
18 | #include <net/netfilter/nf_conntrack.h> | |
19 | #include <net/netfilter/nf_conntrack_helper.h> | |
20 | #include <net/netfilter/nf_conntrack_expect.h> | |
21 | ||
22 | int nf_conntrack_broadcast_help(struct sk_buff *skb, | |
23 | unsigned int protoff, | |
24 | struct nf_conn *ct, | |
25 | enum ip_conntrack_info ctinfo, | |
26 | unsigned int timeout) | |
27 | { | |
28 | struct nf_conntrack_expect *exp; | |
29 | struct iphdr *iph = ip_hdr(skb); | |
30 | struct rtable *rt = skb_rtable(skb); | |
31 | struct in_device *in_dev; | |
32 | struct nf_conn_help *help = nfct_help(ct); | |
33 | __be32 mask = 0; | |
34 | ||
35 | /* we're only interested in locally generated packets */ | |
36 | if (skb->sk == NULL) | |
37 | goto out; | |
38 | if (rt == NULL || !(rt->rt_flags & RTCF_BROADCAST)) | |
39 | goto out; | |
40 | if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) | |
41 | goto out; | |
42 | ||
43 | rcu_read_lock(); | |
44 | in_dev = __in_dev_get_rcu(rt->dst.dev); | |
45 | if (in_dev != NULL) { | |
46 | for_primary_ifa(in_dev) { | |
47 | if (ifa->ifa_broadcast == iph->daddr) { | |
48 | mask = ifa->ifa_mask; | |
49 | break; | |
50 | } | |
51 | } endfor_ifa(in_dev); | |
52 | } | |
53 | rcu_read_unlock(); | |
54 | ||
55 | if (mask == 0) | |
56 | goto out; | |
57 | ||
58 | exp = nf_ct_expect_alloc(ct); | |
59 | if (exp == NULL) | |
60 | goto out; | |
61 | ||
62 | exp->tuple = ct->tuplehash[IP_CT_DIR_REPLY].tuple; | |
63 | exp->tuple.src.u.udp.port = help->helper->tuple.src.u.udp.port; | |
64 | ||
65 | exp->mask.src.u3.ip = mask; | |
66 | exp->mask.src.u.udp.port = htons(0xFFFF); | |
67 | ||
68 | exp->expectfn = NULL; | |
69 | exp->flags = NF_CT_EXPECT_PERMANENT; | |
70 | exp->class = NF_CT_EXPECT_CLASS_DEFAULT; | |
71 | exp->helper = NULL; | |
72 | ||
73 | nf_ct_expect_related(exp); | |
74 | nf_ct_expect_put(exp); | |
75 | ||
76 | nf_ct_refresh(ct, skb, timeout * HZ); | |
77 | out: | |
78 | return NF_ACCEPT; | |
79 | } | |
80 | EXPORT_SYMBOL_GPL(nf_conntrack_broadcast_help); | |
81 | ||
82 | MODULE_LICENSE("GPL"); |