Re: [RCF] [PATCH] unprivileged mount/umount

[Bill Davidsen <davidsen@tmr.com>]

Miklos Szeredi wrote:
> This (lightly tested) patch against 2.6.12-rc* adds some
> infrastructure and basic functionality for unprivileged mount/umount
> system calls.
> 
> Details:
> 
>   - new mnt_owner field in struct vfsmount
>   - if mnt_owner is NULL, it's a privileged mount
>   - global limit on unprivileged mounts in  /proc/sys/fs/mount-max
>   - per user limit of mounts in rlimit
>   - allow umount for the owner (except force flag)
>   - allow unprivileged bind mount to files/directories writable by owner
>   - add nosuid,nodev flags to unprivileged mounts
> 
> Next step would be to add some policy for new mounts.  I'm thinking of
> either something static: e.g. FS_SAFE flag for "safe" filesystems, or
> a more configurable approach through sysfs or something.
> 
> Comments?

Are these public or private mounts? In other words, is the mount visible 
only to the mounting process and children, or is it visible to (and can 
effect) other processes. Clearly true private mounts open uses with 
chroot jails and virtualization.

-- 
    -bill davidsen (davidsen@tmr.com)
"The secret to procrastination is to put things off until the
  last possible moment - but no longer"  -me