[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@opteya.com>
---
 net/sctp/socket.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

On 07/02/2013 12:39 PM, Yann Droneaud wrote:
> 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>

-vlad

> ---
>   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;
>

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From: Vlad Yasevich <vyasevich@gmail.com>
Date: Tue, 02 Jul 2013 13:50:32 -0400

> On 07/02/2013 12:39 PM, Yann Droneaud wrote:
>> 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>

Applied to net-next, thanks.
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