sctp: use get_unused_fd_flags(0) instead of get_unused_fd()

Macro get_unused_fd() is used to allocate a file descriptor with
default flags. Those default flags (0) can be "unsafe":
O_CLOEXEC must be used by default to not leak file descriptor
across exec().

Instead of macro get_unused_fd(), functions anon_inode_getfd()
or get_unused_fd_flags() should be used with flags given by userspace.
If not possible, flags should be set to O_CLOEXEC to provide userspace
with a default safe behavor.

In a further patch, get_unused_fd() will be removed so that
new code start using anon_inode_getfd() or get_unused_fd_flags()
with correct flags.

This patch replaces calls to get_unused_fd() with equivalent call to
get_unused_fd_flags(0) to preserve current behavor for existing code.

The hard coded flag value (0) should be reviewed on a per-subsystem basis,
and, if possible, set to O_CLOEXEC.

Signed-off-by: Yann Droneaud <ydroneaud@opteya.com>
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index d5c6a28..c6670d2 100644 (file)
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -4312,7 +4312,7 @@ static int sctp_getsockopt_peeloff(struct sock *sk, int len, char __user *optval
                goto out;
 
        /* Map the socket to an unused fd that can be returned to the user.  */
-       retval = get_unused_fd();
+       retval = get_unused_fd_flags(0);
        if (retval < 0) {
                sock_release(newsock);
                goto out;