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Re: [PATCH] set sticky bit when creating /var/tmp mount-point



On Tue, Nov 13, 2001 at 12:02:18PM +0100, Kjetil Torgrim Homme wrote:
> Ethan Benson <erbenson@alaska.net> writes:
> 
> > On Tue, Nov 13, 2001 at 10:53:16PM +1300, Mark van Walraven wrote:
> > > partition_config::mount_partition() uses mode 01777 when creating /tmp
> > > as a mount-point, but doesn't for /target/var/tmp.  A fix is:
> > 
> > what good will this do?  the permissions of the mount point
> > directory are irrelevant as they will be replaced by the permissions
> > of the root directory of the mounted filesystem.
> 
> It enables the use of vi for non-root users even when /var/tmp isn't
> mounted ... uh ...

and why would that happen?  from a security point of view i think the
directory under mountpoints like tmp should not be world writable, if
the admin has a different filesystem/partition mounted there he
probably did so to keep users from gaining write permission to the
underlying filesystem (esp in the case of /). 

> No, actually, if you use tmpfs for /var/tmp, it will use the same
> permissions as the mount point, since there is no other place to store
> that persistent configuration.

this is not true:

root@dogbert /# mkdir foo
root@dogbert /# ls -ld foo/
drwxr-xr-x    2 root     root         1024 Nov 13 04:14 foo/
root@dogbert /# mount -t tmpfs tmpfs foo
root@dogbert /# ls -ld foo/
drwxrwxrwt    2 root     root            0 Nov 13 04:14 foo/
root@dogbert /# uname -a
Linux dogbert 2.4.14 #1 Sun Nov 11 01:20:42 AKST 2001 ppc unknown

default permissions for the tmpfs root is 1777 if you want something
different you have to use the mode= mount option.

-- 
Ethan Benson
http://www.alaska.net/~erbenson/

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