linux-kernel - [PATCH 12/13] sctp: use get_unused_fd_flags(0) instead of get_unused

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Message-Id: <6d4271e2e0b05ae2728cba1d890e77cac50cf8f0.1372777600.git.ydroneaud@opteya.com>
Date:	Tue,  2 Jul 2013 18:39:36 +0200
From:	Yann Droneaud <ydroneaud@...eya.com>
To:	linux-kernel@...r.kernel.org, linux-sctp@...r.kernel.org,
	netdev@...r.kernel.org
Cc:	Yann Droneaud <ydroneaud@...eya.com>
Subject: [PATCH 12/13] 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@...eya.com>
---
 net/sctp/socket.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 66fcdcf..caa5919 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -4320,7 +4320,7 @@ 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;
-- 
1.8.3.1

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