linux-kernel - [PATCH v2 05/10] vfio: use get_unused_fd_flags(0) instead of get_unused

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Message-Id: <613180f8dafa1143cc4f71405b0c1eba8d523000.1376327678.git.ydroneaud@opteya.com>
Date:	Thu, 15 Aug 2013 15:10:55 +0200
From:	Yann Droneaud <ydroneaud@...eya.com>
To:	Alex Williamson <alex.williamson@...hat.com>
Cc:	Yann Droneaud <ydroneaud@...eya.com>, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 05/10] vfio: 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>
Link: http://lkml.kernel.org/r/cover.1376327678.git.ydroneaud@opteya.com

---
 drivers/vfio/vfio.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index d3cb342..75c16cc 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -1109,7 +1109,7 @@ static int vfio_group_get_device_fd(struct vfio_group *group, char *buf)
 		 * We can't use anon_inode_getfd() because we need to modify
 		 * the f_mode flags directly to allow more than just ioctls
 		 */
-		ret = get_unused_fd();
+		ret = get_unused_fd_flags(0);
 		if (ret < 0) {
 			device->ops->release(device->device_data);
 			break;
-- 
1.8.3.1

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