linux-kernel - Re: [REVIEW][PATCH 6/6] fs: Allow CAP_SYS_ADMIN in s_user

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Date:   Thu, 24 May 2018 17:59:44 +0200
From:   Christian Brauner <christian@...uner.io>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     Linux Containers <containers@...ts.linux-foundation.org>,
        linux-fsdevel@...r.kernel.org,
        Seth Forshee <seth.forshee@...onical.com>,
        "Serge E. Hallyn" <serge@...lyn.com>, linux-kernel@...r.kernel.org
Subject: Re: [REVIEW][PATCH 6/6] fs: Allow CAP_SYS_ADMIN in s_user_ns to
 freeze and thaw filesystems

On Wed, May 23, 2018 at 06:25:38PM -0500, Eric W. Biederman wrote:
> From: Seth Forshee <seth.forshee@...onical.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.

Acked-by: Christian Brauner <christian@...uner.io>

> 
> Signed-off-by: Seth Forshee <seth.forshee@...onical.com>
> Signed-off-by: Eric W. Biederman <ebiederm@...ssion.com>
> ---
>  fs/ioctl.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/ioctl.c b/fs/ioctl.c
> index 4823431d1c9d..b445b13fc59b 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 */
> -- 
> 2.14.1
>