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From: Christian Brauner <christian@brauner.io>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Linux Containers <containers@lists.linux-foundation.org>,
	linux-fsdevel@vger.kernel.org,
	Seth Forshee <seth.forshee@canonical.com>,
	"Serge E. Hallyn" <serge@hallyn.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [REVIEW][PATCH 2/6] vfs: Allow userns root to call mknod on owned filesystems.
Date: Thu, 24 May 2018 21:12:32 +0200	[thread overview]
Message-ID: <20180524191232.GA7573@mailbox.org> (raw)
In-Reply-To: <20180523232538.4880-2-ebiederm@xmission.com>

On Wed, May 23, 2018 at 06:25:34PM -0500, Eric W. Biederman wrote:
> These filesystems already always set SB_I_NODEV so mknod will not be
> useful for gaining control of any devices no matter their permissions.
> This will allow overlayfs and applications to fakeroot to use device
> nodes to represent things on disk.

Excellent.

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

> 
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
> ---
>  fs/namei.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/namei.c b/fs/namei.c
> index 942c1f096f6b..20335896dcce 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -3679,7 +3679,8 @@ int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
>  	if (error)
>  		return error;
>  
> -	if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD))
> +	if ((S_ISCHR(mode) || S_ISBLK(mode)) &&
> +	    !ns_capable(dentry->d_sb->s_user_ns, CAP_MKNOD))
>  		return -EPERM;
>  
>  	if (!dir->i_op->mknod)
> -- 
> 2.14.1
> 

  parent reply	other threads:[~2018-05-24 19:12 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-23 23:22 [REVIEW][PATCH 0/6] Wrapping up the vfs support for unprivileged mounts Eric W. Biederman
2018-05-23 23:25 ` [REVIEW][PATCH 1/6] vfs: Don't allow changing the link count of an inode with an invalid uid or gid Eric W. Biederman
2018-05-24 12:58   ` Seth Forshee
2018-05-24 22:30     ` Christian Brauner
2018-05-23 23:25 ` [REVIEW][PATCH 2/6] vfs: Allow userns root to call mknod on owned filesystems Eric W. Biederman
2018-05-24 13:55   ` Seth Forshee
2018-05-24 16:55     ` Eric W. Biederman
2018-05-24 17:22       ` Seth Forshee
2018-05-24 19:12   ` Christian Brauner [this message]
2018-05-23 23:25 ` [REVIEW][PATCH 3/6] fs: Allow superblock owner to replace invalid owners of inodes Eric W. Biederman
2018-05-23 23:41   ` [REVIEW][PATCH v2 " Eric W. Biederman
2018-05-24 22:30     ` Christian Brauner
2018-05-23 23:25 ` [REVIEW][PATCH 4/6] fs: Allow superblock owner to access do_remount_sb() Eric W. Biederman
2018-05-24 15:58   ` Christian Brauner
2018-05-24 16:45     ` Eric W. Biederman
2018-05-24 17:28       ` Christian Brauner
2018-05-23 23:25 ` [REVIEW][PATCH 5/6] capabilities: Allow privileged user in s_user_ns to set security.* xattrs Eric W. Biederman
2018-05-24 15:57   ` Christian Brauner
2018-05-23 23:25 ` [REVIEW][PATCH 6/6] fs: Allow CAP_SYS_ADMIN in s_user_ns to freeze and thaw filesystems Eric W. Biederman
2018-05-24 15:59   ` Christian Brauner
2018-05-24 21:46 ` [REVIEW][PATCH 0/6] Wrapping up the vfs support for unprivileged mounts Theodore Y. Ts'o
2018-05-24 23:23   ` Eric W. Biederman
2018-05-25  3:57     ` Dave Chinner
2018-05-25  4:06       ` Darrick J. Wong
2018-05-29 13:12       ` Eric W. Biederman
2018-05-29 22:17         ` Dave Chinner
2018-05-30  2:34           ` Eric W. Biederman
2018-05-30  4:34             ` Dave Chinner
2018-05-29 15:40 ` Dongsu Park

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