On 4/11/05, Miklos Szeredi <[EMAIL PROTECTED]> wrote:
>
> 1) Only allow mount over a directory for which the user has write
> access (and is not sticky)
>
> 2) Use nosuid,nodev mount options
>
> [ parts deleted ]
Do these solve all the security concerns with unprivileged mounts, or
are there other barriers/concerns? Should there be ulimit (or rlimit)
style restrictions on how many mounts/binds a user is allowed to have
to prevent users from abusing mount privs?
I was thinking about this a while back and thought having a user-mount
permissions file might be the right way to address lots of these
issues. Essentially it would contain information about what
users/groups were allowed to mount what sources to what destinations
and with what mandatory options.
You can get the start of this with the user/users/etc. stuff in
/etc/fstab, but I was envisioning something a bit more dynamic with
regular expression based rules for sources and destinations. So,
something like:
# /etc/usermounts: user mount permissions
# <fs> <mount point> <type> <opts>
# allow users to mount any file system under their home directory
* $HOME *
nosuid, nosgid
# allow users to bind over /usr/bin as long as its only in their
private namespace
* /usr/bin
bind newns
# allow users to loopback mount distributed file systems to /mnt
127.0.0.1 /mnt *
nosuid, nosgid
# allow users to mount files over any directory they have right access to
* (perm=0222) *
nosuid, nosgid
Is this unnecessary? Is this not enough?
-eric
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