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l2tp: lock socket before checking flags in connect() 

Socket flags aren't updated atomically, so the socket must be locked
while reading the SOCK_ZAPPED flag.

This issue exists for both l2tp_ip and l2tp_ip6. For IPv6, this patch
also brings error handling for __ip6_datagram_connect() failures.

Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Guillaume Nault 2016-11-29 13:09:44 +01:00 committed by David S. Miller
parent bb83d62fa8
commit 0382a25af3
4 changed files with 28 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/net/ipv6.h
View File

@ -970,6 +970,8 @@ int compat_ipv6_setsockopt(struct sock *sk, int level, int optname,
int compat_ipv6_getsockopt(struct sock *sk, int level, int optname,
char __user *optval, int __user *optlen);
int __ip6_datagram_connect(struct sock *sk, struct sockaddr *addr,
int addr_len);
int ip6_datagram_connect(struct sock *sk, struct sockaddr *addr, int addr_len);
int ip6_datagram_connect_v6_only(struct sock *sk, struct sockaddr *addr,
int addr_len);

4
net/ipv6/datagram.c
View File

@ -139,7 +139,8 @@ void ip6_datagram_release_cb(struct sock *sk)
}
EXPORT_SYMBOL_GPL(ip6_datagram_release_cb);
static int __ip6_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
int __ip6_datagram_connect(struct sock *sk, struct sockaddr *uaddr,
int addr_len)
{
struct sockaddr_in6 *usin = (struct sockaddr_in6 *) uaddr;
struct inet_sock *inet = inet_sk(sk);
@ -252,6 +253,7 @@ ipv4_connected:
out:
return err;
}
EXPORT_SYMBOL_GPL(__ip6_datagram_connect);
int ip6_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
{

19
net/l2tp/l2tp_ip.c
View File

@ -308,21 +308,24 @@ static int l2tp_ip_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len
struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *) uaddr;
int rc;
if (sock_flag(sk, SOCK_ZAPPED)) /* Must bind first - autobinding does not work */
return -EINVAL;
if (addr_len < sizeof(*lsa))
return -EINVAL;
if (ipv4_is_multicast(lsa->l2tp_addr.s_addr))
return -EINVAL;
rc = ip4_datagram_connect(sk, uaddr, addr_len);
if (rc < 0)
return rc;
lock_sock(sk);
/* Must bind first - autobinding does not work */
if (sock_flag(sk, SOCK_ZAPPED)) {
rc = -EINVAL;
goto out_sk;
}
rc = __ip4_datagram_connect(sk, uaddr, addr_len);
if (rc < 0)
goto out_sk;
l2tp_ip_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
write_lock_bh(&l2tp_ip_lock);
@ -330,7 +333,9 @@ static int l2tp_ip_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len
sk_add_bind_node(sk, &l2tp_ip_bind_table);
write_unlock_bh(&l2tp_ip_lock);
out_sk:
release_sock(sk);
return rc;
}

16
net/l2tp/l2tp_ip6.c
View File

@ -371,9 +371,6 @@ static int l2tp_ip6_connect(struct sock *sk, struct sockaddr *uaddr,
int addr_type;
int rc;
if (sock_flag(sk, SOCK_ZAPPED)) /* Must bind first - autobinding does not work */
return -EINVAL;
if (addr_len < sizeof(*lsa))
return -EINVAL;
@ -390,10 +387,18 @@ static int l2tp_ip6_connect(struct sock *sk, struct sockaddr *uaddr,
return -EINVAL;
}
rc = ip6_datagram_connect(sk, uaddr, addr_len);
lock_sock(sk);
/* Must bind first - autobinding does not work */
if (sock_flag(sk, SOCK_ZAPPED)) {
rc = -EINVAL;
goto out_sk;
}
rc = __ip6_datagram_connect(sk, uaddr, addr_len);
if (rc < 0)
goto out_sk;
l2tp_ip6_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
write_lock_bh(&l2tp_ip6_lock);
@ -401,6 +406,7 @@ static int l2tp_ip6_connect(struct sock *sk, struct sockaddr *uaddr,
sk_add_bind_node(sk, &l2tp_ip6_bind_table);
write_unlock_bh(&l2tp_ip6_lock);
out_sk:
release_sock(sk);
return rc;