lkml.org 
[lkml]   [2012]   [Mar]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] proc: fix mount -t proc -o AAA
On Fri, Mar 23, 2012 at 16:15 -0700, Andrew Morton wrote:
> I'm surprised. "mount -o remount,<options>" doesn't work on a mounted
> procfs, and nobody noticed until now?
>
> The patch looks OK - has it been tested with both valid and invalid
> mount options?
>
>
> I redid the changelog:
>
>
> From: Vasiliy Kulikov <segoon@openwall.com>
> Subject: proc: fix mount -t proc -o AAA
>
> The proc_parse_options() call from proc_mount() runs only once at boot
> time. So on any later mount attempt, any mount options are ignored
> because ->s_root is already initialized.
>
> As a consequence, "mount -o remount,<options>" will ignore the options.

No, remount works as it should. _mount_ doesn't work. Why it was not spotted:
Live case is:

1) upstart and systemd don't use /etc/fstab for /proc when mounting it at
the boot time.
2) dbus, etc. use /proc/ from the boot, so /proc cannot be umounted without
dbus stop.

So, to apply hidepid=X without system reboot procfs should be remounted
instead of umount+mount.

> To fix this, parse the mount options unconditionally.

--
Vasiliy Kulikov
http://www.openwall.com - bringing security into open computing environments


\
 
 \ /
  Last update: 2012-03-25 17:31    [W:0.077 / U:0.096 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site