Messages in this thread Patch in this message | | | From | "Rafael J. Wysocki" <> | Subject | Re: chroot in swsusp userland interface (was: Re: [Suspend2-devel] Re: [ 00/10] [Suspend2] Modules support.) | Date | Sat, 4 Feb 2006 21:45:42 +0100 |
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Hi,
On Saturday 04 February 2006 21:15, Pavel Machek wrote: }-- snip --{ > > > Index: suspend.c > > > =================================================================== > > > RCS file: /cvsroot/suspend/suspend/suspend.c,v > > > retrieving revision 1.5 > > > diff -u -u -r1.5 suspend.c > > > --- suspend.c 3 Feb 2006 22:39:24 -0000 1.5 > > > +++ suspend.c 4 Feb 2006 19:19:51 -0000 > > > @@ -360,6 +360,12 @@ > > > goto Close; > > > } > > > go_to_console(); > > > + /* > > > + * From now on, system is frozen; any filesystem access may mean data corruption. > > > + * Prevent accidental filesystem accesses by chrooting somewhere where little > > > + * damage can be done. > > > + */ > > > + chroot("/sys/power"); > > > > This won't be enough if /sys/power is on a frozen ext2 and the suspending > > utility calls open("file", O_CREAT) "by accident". > > ...well, we rely on sysfs files to work... at least for > suspend-to-RAM, ok, no argument here. I doubt anyone really does mount > anything but sysfs on /sys... > > > I think we should do as Olivier said: Mount tmpfs with limited size somewhere > > and chroot to it (IMO this won't affect the underlying filesystem). Then, create > > device files for the console and vt on it and open them from there. This should > > be 100% safe. > > Looks unneccessarily complex to me. We'd have to umount that tmpfs, > and playing with mounts inside system suspend seems wrong to me. > > Perhaps we can chroot into /proc... almost everyone has /proc > mounted, right? > > Is it possible to move console/vt open before freeze?
No, because freeze sets the active vt for us. How about that: mount the tmpfs before freeze, put there what we'll need, open device files from there instead of /dev, and chroot() after atomic_snapshot? Then, after resume we won't be chrooted and we'll be able to unmount the tmpfs safely.
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