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.na...@alphalink.fr>
---
include/net/ipv6.h | 2 ++
net/ipv6/datagram.c | 4 +++-
net/l2tp/l2tp_ip.c | 19 ++++++++++++-------
net/l2tp/l2tp_ip6.c | 16 +++++++++++-----
4 files changed, 28 insertions(+), 13 deletions(-)
diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 8fed1cd..f11ca83 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -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);
diff --git a/net/ipv6/datagram.c b/net/ipv6/datagram.c
index 37874e2..ccf4055 100644
--- a/net/ipv6/datagram.c
+++ b/net/ipv6/datagram.c
@@ -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 @@ static int __ip6_datagram_connect(struct sock *sk, struct
sockaddr *uaddr, int a
out:
return err;
}
+EXPORT_SYMBOL_GPL(__ip6_datagram_connect);
int ip6_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
{
diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c
index 982f6c4..1f57094 100644
--- a/net/l2tp/l2tp_ip.c
+++ b/net/l2tp/l2tp_ip.c
@@ -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;
}
diff --git a/net/l2tp/l2tp_ip6.c b/net/l2tp/l2tp_ip6.c
index 9978d01..af9abff 100644
--- a/net/l2tp/l2tp_ip6.c
+++ b/net/l2tp/l2tp_ip6.c
@@ -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;
--
2.10.2
