Bug#2045: smb[u]mount not suid root
> Where does it say they are suid safe?
>From the smbmount(8) man page:
If the real uid of the caller is not root, smbmount
checks whether the user is allowed to mount a filesys-
tem on the mount-point. So it should be safe to make
smbmount setuid root. In the filesystem, the real uid
of the caller is stored, so that smbumount can check
whether the caller is allowed to unmount the filesys-
tem.
Also, from the smbumount(8) man page:
With this program, normal users can unmount smb-
filesystems, provided that it is suid root.
smbumount has been written to give normal linux-users more
control over their resources. It is safe to install this
program suid root, because only the user who has mounted a
filesystem is allowed to unmount it again.
For root it is not necessary to use smbumount. The normal
umount program works perfectly well, but it would cer-
tainly be problematic to make umount setuid root.
(Actually, the Debian umount is suid-safe, but won't unmount user-mounted SMB
filesystems unless run as root.)
> What is different between a user mounting a NFS and a smbfs, why should
> normal users be able to do this?
There isn't much difference; users can be allowed to mount NFS filesystems
with proper /etc/fstab entries.
An important difference, though, is that smbfs treats ownership of all files
and directories to be the same as the user who mounted the filesystem. So, it
doesn't work well to require root to mount an SMB filesystem for a user (say,
the user's home directory on an SMB server) because all the files will
effectively be owned by root.
--
Robert Leslie
rob@advantage.org
Reply to: