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 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