linux-kernel - Re: [patch 05/10] Add "permit user submounts" flag to vfsmount

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Message-ID: <20070416192050.GB30435@sergelap.austin.ibm.com>
Date:	Mon, 16 Apr 2007 14:20:50 -0500
From:	"Serge E. Hallyn" <serue@...ibm.com>
To:	Miklos Szeredi <miklos@...redi.hu>
Cc:	akpm@...ux-foundation.org, viro@....linux.org.uk,
	linuxram@...ibm.com, ebiederm@...ssion.com,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	containers@...ts.osdl.org
Subject: Re: [patch 05/10] Add "permit user submounts" flag to vfsmount

Quoting Miklos Szeredi (miklos@...redi.hu):
> From: Miklos Szeredi <mszeredi@...e.cz>
> 
> If MNT_USERMNT flag is not set in the target vfsmount, then

MNT_USER and MNT_USERMNT?  I claim no way will people keep those
straight.  How about MNT_ALLOWUSER and MNT_USER?

-serge

> unprivileged mounts will be denied.
> 
> By default this flag is cleared, and can be set on new mounts, on
> remounts or with the MS_SETFLAGS option.
> 
> Signed-off-by: Miklos Szeredi <mszeredi@...e.cz>
> ---
> 
> Index: linux/fs/namespace.c
> ===================================================================
> --- linux.orig/fs/namespace.c	2007-04-13 13:20:12.000000000 +0200
> +++ linux/fs/namespace.c	2007-04-13 13:35:40.000000000 +0200
> @@ -411,6 +411,7 @@ static int show_vfsmnt(struct seq_file *
>  		{ MNT_NOATIME, ",noatime" },
>  		{ MNT_NODIRATIME, ",nodiratime" },
>  		{ MNT_RELATIME, ",relatime" },
> +		{ MNT_USERMNT, ",usermnt" },
>  		{ 0, NULL }
>  	};
>  	struct proc_fs_info *fs_infop;
> @@ -1505,9 +1506,11 @@ long do_mount(char *dev_name, char *dir_
>  		mnt_flags |= MNT_NODIRATIME;
>  	if (flags & MS_RELATIME)
>  		mnt_flags |= MNT_RELATIME;
> +	if (flags & MS_USERMNT)
> +		mnt_flags |= MNT_USERMNT;
> 
>  	flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE |
> -		   MS_NOATIME | MS_NODIRATIME | MS_RELATIME);
> +		   MS_NOATIME | MS_NODIRATIME | MS_RELATIME | MS_USERMNT);
> 
>  	/* ... and get the mountpoint */
>  	retval = path_lookup(dir_name, LOOKUP_FOLLOW, &nd);
> Index: linux/include/linux/mount.h
> ===================================================================
> --- linux.orig/include/linux/mount.h	2007-04-13 13:17:08.000000000 +0200
> +++ linux/include/linux/mount.h	2007-04-13 13:22:17.000000000 +0200
> @@ -28,6 +28,7 @@ struct mnt_namespace;
>  #define MNT_NOATIME	0x08
>  #define MNT_NODIRATIME	0x10
>  #define MNT_RELATIME	0x20
> +#define MNT_USERMNT	0x40
> 
>  #define MNT_SHRINKABLE	0x100
>  #define MNT_USER	0x200
> Index: linux/include/linux/fs.h
> ===================================================================
> --- linux.orig/include/linux/fs.h	2007-04-13 13:23:05.000000000 +0200
> +++ linux/include/linux/fs.h	2007-04-13 13:35:34.000000000 +0200
> @@ -130,6 +130,7 @@ extern int dir_notify_enable;
>  #define MS_SETFLAGS	(1<<23) /* set specified mount flags */
>  #define MS_CLEARFLAGS	(1<<24) /* clear specified mount flags */
>  /* MS_SETFLAGS | MS_CLEARFLAGS: change mount flags to specified */
> +#define MS_USERMNT	(1<<25) /* permit unpriv. submounts under this mount */
>  #define MS_ACTIVE	(1<<30)
>  #define MS_NOUSER	(1<<31)
> 
> 
> --
-
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