Messages in this thread | | | Date | Sun, 25 Mar 2012 19:27:36 +0400 | From | Vasiliy Kulikov <> | Subject | Re: [PATCH] proc: fix mount -t proc -o AAA |
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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
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