Re: FUSE merging?

[Miklos Szeredi <miklos@szeredi.hu>]

> >  - I don't recall seeing an exhaustive investigation of how an
> >    unprivileged user could use a FUSE mount to implement DoS attacks against
> >    other users or against root.
> 
> You say
> 
>   "If a sysadmin trusts the users enough, or can ensure through other
>    measures, that system processes will never enter non-privileged mounts,
>    it can relax the last limitation with a "user_allow_other" config
>    option.  If this config option is set, the mounting user can add the
>    "allow_other" mount option which disables the check for other users'
>    processes."
> 
> What config option, where?

Currently that's a userspace issue.  There's a /etc/fuse.conf file,
with two options:

  max_mounts=X
  user_allow_other

The fusermount helper reads this file, and decides if passing the
'allow_other' mount option to the kernel is OK or not.

If we want unprivileged sys_mount() these will have to be checked in
kernel (set via sysfs, etc).

Miklos
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