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