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net: ipv6: Fix UDP early demux lookup with udp_l3mdev_accept=0 

David Ahern reported that 5425077d73 ("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: 5425077d73 ("net: ipv6: Add early demux handler for UDP unicast")
Reported-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
Cc: Eric Dumazet <edumazet@google.com>
Acked-by: David Ahern <dsa@cumulusnetworks.com>
Tested-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
subashab@codeaurora.org 2017-04-18 11:39:41 -06:00 committed by David S. Miller
parent 8ad0921b8a
commit 0bd84065b1
1 changed files with 15 additions and 9 deletions
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24
net/ipv6/udp.c
View File

@ -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 @@ discard:
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();
return sk;
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;