| 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 | const struct nf_conntrack_helper *helper; |
| 24 | struct nf_conntrack_expect *exp; |
| 25 | struct iphdr *iph = ip_hdr(skb); |
| 26 | struct rtable *rt = skb_rtable(skb); |
| 27 | struct in_device *in_dev; |
| 28 | struct nf_conn_help *help = nfct_help(ct); |
| 29 | __be32 mask = 0; |
| 30 | |
| 31 | /* we're only interested in locally generated packets */ |
| 32 | if (skb->sk == NULL || !net_eq(net1: nf_ct_net(ct), net2: sock_net(sk: skb->sk))) |
| 33 | goto out; |
| 34 | if (rt == NULL || !(rt->rt_flags & RTCF_BROADCAST)) |
| 35 | goto out; |
| 36 | if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) |
| 37 | goto out; |
| 38 | |
| 39 | in_dev = __in_dev_get_rcu(dev: rt->dst.dev); |
| 40 | if (in_dev != NULL) { |
| 41 | const struct in_ifaddr *ifa; |
| 42 | |
| 43 | in_dev_for_each_ifa_rcu(ifa, in_dev) { |
| 44 | if (ifa->ifa_flags & IFA_F_SECONDARY) |
| 45 | continue; |
| 46 | |
| 47 | if (ifa->ifa_broadcast == iph->daddr) { |
| 48 | mask = ifa->ifa_mask; |
| 49 | break; |
| 50 | } |
| 51 | } |
| 52 | } |
| 53 | |
| 54 | if (mask == 0) |
| 55 | goto out; |
| 56 | |
| 57 | exp = nf_ct_expect_alloc(me: ct); |
| 58 | if (exp == NULL) |
| 59 | goto out; |
| 60 | |
| 61 | exp->tuple = ct->tuplehash[IP_CT_DIR_REPLY].tuple; |
| 62 | |
| 63 | helper = rcu_dereference(help->helper); |
| 64 | if (helper) |
| 65 | exp->tuple.src.u.udp.port = helper->tuple.src.u.udp.port; |
| 66 | |
| 67 | exp->mask.src.u3.ip = mask; |
| 68 | exp->mask.src.u.udp.port = htons(0xFFFF); |
| 69 | |
| 70 | exp->expectfn = NULL; |
| 71 | exp->flags = NF_CT_EXPECT_PERMANENT; |
| 72 | exp->class = NF_CT_EXPECT_CLASS_DEFAULT; |
| 73 | exp->helper = NULL; |
| 74 | |
| 75 | nf_ct_expect_related(expect: exp, flags: 0); |
| 76 | nf_ct_expect_put(exp); |
| 77 | |
| 78 | nf_ct_refresh(ct, skb, extra_jiffies: timeout * HZ); |
| 79 | out: |
| 80 | return NF_ACCEPT; |
| 81 | } |
| 82 | EXPORT_SYMBOL_GPL(nf_conntrack_broadcast_help); |
| 83 | |
| 84 | MODULE_LICENSE("GPL"); |
| 85 |