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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* broadcast connection tracking helper
*
* (c) 2005 Patrick McHardy <kaber@trash.net>
*/
#include <linux/module.h>
#include <linux/ip.h>
#include <net/route.h>
#include <linux/inetdevice.h>
#include <linux/skbuff.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_expect.h>
int nf_conntrack_broadcast_help(struct sk_buff *skb,
struct nf_conn *ct,
enum ip_conntrack_info ctinfo,
unsigned int timeout)
{
const struct nf_conntrack_helper *helper;
struct nf_conntrack_expect *exp;
struct iphdr *iph = ip_hdr(skb);
struct rtable *rt = skb_rtable(skb);
struct in_device *in_dev;
struct nf_conn_help *help = nfct_help(ct);
__be32 mask = 0;
/* we're only interested in locally generated packets */
if (skb->sk == NULL || !net_eq(nf_ct_net(ct), sock_net(skb->sk)))
goto out;
if (rt == NULL || !(rt->rt_flags & RTCF_BROADCAST))
goto out;
if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL)
goto out;
in_dev = __in_dev_get_rcu(rt->dst.dev);
if (in_dev != NULL) {
const struct in_ifaddr *ifa;
in_dev_for_each_ifa_rcu(ifa, in_dev) {
if (ifa->ifa_flags & IFA_F_SECONDARY)
continue;
if (ifa->ifa_broadcast == iph->daddr) {
mask = ifa->ifa_mask;
break;
}
}
}
if (mask == 0)
goto out;
exp = nf_ct_expect_alloc(ct);
if (exp == NULL)
goto out;
exp->tuple = ct->tuplehash[IP_CT_DIR_REPLY].tuple;
helper = rcu_dereference(help->helper);
if (helper)
exp->tuple.src.u.udp.port = helper->tuple.src.u.udp.port;
exp->mask.src.u3.ip = mask;
exp->mask.src.u.udp.port = htons(0xFFFF);
exp->expectfn = NULL;
exp->flags = NF_CT_EXPECT_PERMANENT;
exp->class = NF_CT_EXPECT_CLASS_DEFAULT;
exp->helper = NULL;
nf_ct_expect_related(exp, 0);
nf_ct_expect_put(exp);
nf_ct_refresh(ct, skb, timeout * HZ);
out:
return NF_ACCEPT;
}
EXPORT_SYMBOL_GPL(nf_conntrack_broadcast_help);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Broadcast connection tracking helper");
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