1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * broadcast connection tracking helper 4 * 5 * (c) 2005 Patrick McHardy <kaber@trash.net> 6 */ 7 8 #include <linux/module.h> 9 #include <linux/ip.h> 10 #include <net/route.h> 11 #include <linux/inetdevice.h> 12 #include <linux/skbuff.h> 13 14 #include <net/netfilter/nf_conntrack.h> 15 #include <net/netfilter/nf_conntrack_helper.h> 16 #include <net/netfilter/nf_conntrack_expect.h> 17 18 int nf_conntrack_broadcast_help(struct sk_buff *skb, 19 struct nf_conn *ct, 20 enum ip_conntrack_info ctinfo, 21 unsigned int timeout) 22 { 23 struct nf_conntrack_expect *exp; 24 struct iphdr *iph = ip_hdr(skb); 25 struct rtable *rt = skb_rtable(skb); 26 struct in_device *in_dev; 27 struct nf_conn_help *help = nfct_help(ct); 28 __be32 mask = 0; 29 30 /* we're only interested in locally generated packets */ 31 if (skb->sk == NULL || !net_eq(nf_ct_net(ct), sock_net(skb->sk))) 32 goto out; 33 if (rt == NULL || !(rt->rt_flags & RTCF_BROADCAST)) 34 goto out; 35 if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) 36 goto out; 37 38 in_dev = __in_dev_get_rcu(rt->dst.dev); 39 if (in_dev != NULL) { 40 const struct in_ifaddr *ifa; 41 42 in_dev_for_each_ifa_rcu(ifa, in_dev) { 43 if (ifa->ifa_flags & IFA_F_SECONDARY) 44 continue; 45 46 if (ifa->ifa_broadcast == iph->daddr) { 47 mask = ifa->ifa_mask; 48 break; 49 } 50 } 51 } 52 53 if (mask == 0) 54 goto out; 55 56 exp = nf_ct_expect_alloc(ct); 57 if (exp == NULL) 58 goto out; 59 60 exp->tuple = ct->tuplehash[IP_CT_DIR_REPLY].tuple; 61 exp->tuple.src.u.udp.port = help->helper->tuple.src.u.udp.port; 62 63 exp->mask.src.u3.ip = mask; 64 exp->mask.src.u.udp.port = htons(0xFFFF); 65 66 exp->expectfn = NULL; 67 exp->flags = NF_CT_EXPECT_PERMANENT; 68 exp->class = NF_CT_EXPECT_CLASS_DEFAULT; 69 exp->helper = NULL; 70 71 nf_ct_expect_related(exp, 0); 72 nf_ct_expect_put(exp); 73 74 nf_ct_refresh(ct, skb, timeout * HZ); 75 out: 76 return NF_ACCEPT; 77 } 78 EXPORT_SYMBOL_GPL(nf_conntrack_broadcast_help); 79 80 MODULE_LICENSE("GPL"); 81