Date: Fri, 22 Dec 2017 21:39:18 -0600
From: "Serge E. Hallyn" <serge@hallyn.com>
To: Dongsu Park <dongsu@kinvolk.io>
Cc: linux-kernel@vger.kernel.org, Miklos Szeredi <mszeredi@redhat.com>,
        containers@lists.linux-foundation.org,
        Seth Forshee <seth.forshee@canonical.com>,
        Alban Crequy <alban@kinvolk.io>,
        "Eric W . Biederman" <ebiederm@xmission.com>,
        Sargun Dhillon <sargun@sargun.me>, linux-fsdevel@vger.kernel.org,
        Alexander Viro <viro@zeniv.linux.org.uk>
Subject: Re: [PATCH 07/11] fs: Allow CAP_SYS_ADMIN in s_user_ns to freeze and
 thaw filesystems
Message-ID: <20171223033918.GG6837@mail.hallyn.com>
References: <cover.1512741134.git.dongsu@kinvolk.io>
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On Fri, Dec 22, 2017 at 03:32:31PM +0100, Dongsu Park wrote:
> From: Seth Forshee <seth.forshee@canonical.com>
> 
> The user in control of a super block should be allowed to freeze
> and thaw it. Relax the restrictions on the FIFREEZE and FITHAW
> ioctls to require CAP_SYS_ADMIN in s_user_ns.
> 
> Cc: linux-fsdevel@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Cc: Alexander Viro <viro@zeniv.linux.org.uk>
> Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
> Signed-off-by: Dongsu Park <dongsu@kinvolk.io>

Reviewed-by: Serge Hallyn <serge@hallyn.com>

> ---
>  fs/ioctl.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/ioctl.c b/fs/ioctl.c
> index 5ace7efb..8c628a8d 100644
> --- a/fs/ioctl.c
> +++ b/fs/ioctl.c
> @@ -549,7 +549,7 @@ static int ioctl_fsfreeze(struct file *filp)
>  {
>  	struct super_block *sb = file_inode(filp)->i_sb;
>  
> -	if (!capable(CAP_SYS_ADMIN))
> +	if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN))
>  		return -EPERM;
>  
>  	/* If filesystem doesn't support freeze feature, return. */
> @@ -566,7 +566,7 @@ static int ioctl_fsthaw(struct file *filp)
>  {
>  	struct super_block *sb = file_inode(filp)->i_sb;
>  
> -	if (!capable(CAP_SYS_ADMIN))
> +	if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN))
>  		return -EPERM;
>  
>  	/* Thaw */
> -- 
> 2.13.6
> 
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