Drop setuid bit from /bin/ntfs-3g

[Chris Coulson]

/bin/ntfs-3g has been installed as setuid-root since xenial, but this is discouraged upstream (see https://www.tuxera.com/community/ntfs-3g-faq/#useroption) and recently contributed to CVE-2019-9755 (https://usn.ubuntu.com/3914-1/). As a hardening improvement, this should not be setuid.

[ Test case ]
Upgrade ntfs-3g and then mount, use and unmount your NTFS volumes as usual.

[ Regression potential ]
This does break one use-case - unprivileged users will not be able to mount NTFS image files. Based on discussions offline, we think this is an edge case and consider it to be an acceptable trade-off. As far as I'm aware, there are no other use-cases that are broken by this change. It doesn't affect automounting of removable volumes or mounting of NTFS block devices (which unprivileged users can't mount anyway). Administrators that want to allow unprivileged users to mount NTFS image files can change the permissions of /bin/ntfs-3g using dpkg-statoverride.

[Chris Coulson (chrisccoulson)]

Note that the security team intends to copy these updates to the security pockets after the SRU verification has been completed.

[Łukasz Zemczak (sil2100)]

Hey Chris! Do you need any action performed on this package? Or will you copy it over soon?

[Launchpad Janitor (janitor)]

This bug was fixed in the package ntfs-3g - 1:2017.3.23-2ubuntu0.18.04.2

---------------
ntfs-3g (1:2017.3.23-2ubuntu0.18.04.2) bionic-security; urgency=medium

  * Fix LP: #1821250 - Don't install /bin/ntfs-3g as setuid root. If
    administrators want to allow unprivileged users to be able to mount NTFS
    images, they can restore this functionality by changing the permissions of
    /bin/ntfs-3g with dpkg-statoverride
    - update debian/ntfs-3g.postinst

 -- Chris Coulson <email address hidden> Thu, 21 Mar 2019 21:33:01 +0000

[Launchpad Janitor (janitor)]

This bug was fixed in the package ntfs-3g - 1:2015.3.14AR.1-1ubuntu0.3

---------------
ntfs-3g (1:2015.3.14AR.1-1ubuntu0.3) xenial-security; urgency=medium

  * Fix LP: #1821250 - Don't install /bin/ntfs-3g as setuid root. If
    administrators want to allow unprivileged users to be able to mount NTFS
    images, they can restore this functionality by changing the permissions of
    /bin/ntfs-3g with dpkg-statoverride
    - update debian/ntfs-3g.postinst

 -- Chris Coulson <email address hidden> Thu, 21 Mar 2019 21:33:36 +0000

[Launchpad Janitor (janitor)]

This bug was fixed in the package ntfs-3g - 1:2017.3.23-2ubuntu0.18.10.2

---------------
ntfs-3g (1:2017.3.23-2ubuntu0.18.10.2) cosmic-security; urgency=medium

  * Fix LP: #1821250 - Don't install /bin/ntfs-3g as setuid root. If
    administrators want to allow unprivileged users to be able to mount NTFS
    images, they can restore this functionality by changing the permissions of
    /bin/ntfs-3g with dpkg-statoverride
    - update debian/ntfs-3g.postinst

 -- Chris Coulson <email address hidden> Thu, 21 Mar 2019 21:23:27 +0000