| // 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"); |