linux-kernel - [PATCH v3 4/8] file: use get_unused_fd_flags(0) instead of get_unused

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Message-Id: <bb52c1e5d60194449e4f22f88e3de8a5b08c1c37.1378460926.git.ydroneaud@opteya.com>
Date:	Fri,  6 Sep 2013 12:39:54 +0200
From:	Yann Droneaud <ydroneaud@...eya.com>
To:	linux-kernel@...r.kernel.org,
	Alexander Viro <viro@...iv.linux.org.uk>
Cc:	linux-fsdevel@...r.kernel.org, Yann Droneaud <ydroneaud@...eya.com>
Subject: [PATCH v3 4/8] file: 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.1378460926.git.ydroneaud@opteya.com
---
 fs/file.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/file.c b/fs/file.c
index 4a78f98..1420d28 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -897,7 +897,7 @@ SYSCALL_DEFINE1(dup, unsigned int, fildes)
 	struct file *file = fget_raw(fildes);

 	if (file) {
-		ret = get_unused_fd();
+		ret = get_unused_fd_flags(0);
 		if (ret >= 0)
 			fd_install(ret, file);
 		else
-- 
1.8.3.1

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