linux-kernel - [PATCH v4 5/7] fanotify: use get_unused_fd_flags(0) instead of get_unused

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Message-Id: <ab677213bb53a5cb6589f117cdab3e0a8628b651.1383121137.git.ydroneaud@opteya.com>
Date:	Wed, 30 Oct 2013 20:47:45 +0100
From:	Yann Droneaud <ydroneaud@...eya.com>
To:	Eric Paris <eparis@...hat.com>
Cc:	Yann Droneaud <ydroneaud@...eya.com>, linux-kernel@...r.kernel.org
Subject: [PATCH v4 5/7] fanotify: 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.1383121137.git.ydroneaud@opteya.com
---
 fs/notify/fanotify/fanotify_user.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index e44cb64..644b9a7 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -69,7 +69,7 @@ static int create_fd(struct fsnotify_group *group,

 	pr_debug("%s: group=%p event=%p\n", __func__, group, event);

-	client_fd = get_unused_fd();
+	client_fd = get_unused_fd_flags(0);
 	if (client_fd < 0)
 		return client_fd;

-- 
1.8.3.1

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