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
nf_conntrack_broadcast_help(struct sk_buff * skb,struct nf_conn * ct,enum ip_conntrack_info ctinfo,unsigned int timeout)22 int nf_conntrack_broadcast_help(struct sk_buff *skb,
23 struct nf_conn *ct,
24 enum ip_conntrack_info ctinfo,
25 unsigned int timeout)
26 {
27 struct nf_conntrack_expect *exp;
28 struct iphdr *iph = ip_hdr(skb);
29 struct rtable *rt = skb_rtable(skb);
30 struct in_device *in_dev;
31 struct nf_conn_help *help = nfct_help(ct);
32 __be32 mask = 0;
33
34 /* we're only interested in locally generated packets */
35 if (skb->sk == NULL || !net_eq(nf_ct_net(ct), sock_net(skb->sk)))
36 goto out;
37 if (rt == NULL || !(rt->rt_flags & RTCF_BROADCAST))
38 goto out;
39 if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL)
40 goto out;
41
42 in_dev = __in_dev_get_rcu(rt->dst.dev);
43 if (in_dev != NULL) {
44 for_primary_ifa(in_dev) {
45 if (ifa->ifa_broadcast == iph->daddr) {
46 mask = ifa->ifa_mask;
47 break;
48 }
49 } endfor_ifa(in_dev);
50 }
51
52 if (mask == 0)
53 goto out;
54
55 exp = nf_ct_expect_alloc(ct);
56 if (exp == NULL)
57 goto out;
58
59 exp->tuple = ct->tuplehash[IP_CT_DIR_REPLY].tuple;
60 exp->tuple.src.u.udp.port = help->helper->tuple.src.u.udp.port;
61
62 exp->mask.src.u3.ip = mask;
63 exp->mask.src.u.udp.port = htons(0xFFFF);
64
65 exp->expectfn = NULL;
66 exp->flags = NF_CT_EXPECT_PERMANENT;
67 exp->class = NF_CT_EXPECT_CLASS_DEFAULT;
68 exp->helper = NULL;
69
70 nf_ct_expect_related(exp);
71 nf_ct_expect_put(exp);
72
73 nf_ct_refresh(ct, skb, timeout * HZ);
74 out:
75 return NF_ACCEPT;
76 }
77 EXPORT_SYMBOL_GPL(nf_conntrack_broadcast_help);
78
79 MODULE_LICENSE("GPL");
80
