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Commit 0bd84065 authored by Subash Abhinov Kasiviswanathan's avatar Subash Abhinov Kasiviswanathan Committed by David S. Miller
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net: ipv6: Fix UDP early demux lookup with udp_l3mdev_accept=0 



David Ahern reported that 5425077d ("net: ipv6: Add early demux
handler for UDP unicast") breaks udp_l3mdev_accept=0 since early
demux for IPv6 UDP was doing a generic socket lookup which does not
require an exact match. Fix this by making UDPv6 early demux match
connected sockets only.

v1->v2: Take reference to socket after match as suggested by Eric
v2->v3: Add comment before break

Fixes: 5425077d ("net: ipv6: Add early demux handler for UDP unicast")
Reported-by: default avatarDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: default avatarSubash Abhinov Kasiviswanathan <subashab@codeaurora.org>
Cc: Eric Dumazet <edumazet@google.com>
Acked-by: default avatarDavid Ahern <dsa@cumulusnetworks.com>
Tested-by: default avatarDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 8ad0921b

net/ipv6/udp.c

+15 −9
Original line number Diff line number Diff line
@@ -46,6 +46,7 @@ 
#include <net/tcp_states.h>

#include <net/ip6_checksum.h>

#include <net/xfrm.h>

#include <net/inet_hashtables.h>

#include <net/inet6_hashtables.h>

#include <net/busy_poll.h>

#include <net/sock_reuseport.h>
@@ -864,21 +865,26 @@ int __udp6_lib_rcv(struct sk_buff *skb, struct udp_table *udptable, 
	return 0;

}





static struct sock *__udp6_lib_demux_lookup(struct net *net,

			__be16 loc_port, const struct in6_addr *loc_addr,

			__be16 rmt_port, const struct in6_addr *rmt_addr,

			int dif)

{

	unsigned short hnum = ntohs(loc_port);

	unsigned int hash2 = udp6_portaddr_hash(net, loc_addr, hnum);

	unsigned int slot2 = hash2 & udp_table.mask;

	struct udp_hslot *hslot2 = &udp_table.hash2[slot2];

	const __portpair ports = INET_COMBINED_PORTS(rmt_port, hnum);

	struct sock *sk;



	rcu_read_lock();

	sk = __udp6_lib_lookup(net, rmt_addr, rmt_port, loc_addr, loc_port,

			       dif, &udp_table, NULL);

	if (sk && !atomic_inc_not_zero(&sk->sk_refcnt))

		sk = NULL;

	rcu_read_unlock();



	udp_portaddr_for_each_entry_rcu(sk, &hslot2->head) {

		if (INET6_MATCH(sk, net, rmt_addr, loc_addr, ports, dif))

			return sk;

		/* Only check first socket in chain */

		break;

	}

	return NULL;

}



static void udp_v6_early_demux(struct sk_buff *skb)
@@ -903,7 +909,7 @@ static void udp_v6_early_demux(struct sk_buff *skb) 
	else

		return;



	if (!sk)

	if (!sk || !atomic_inc_not_zero_hint(&sk->sk_refcnt, 2))

		return;



	skb->sk = sk;