Bug#940848: nfs-utils:CVE-2019-3689: root-owned files stored in insecure /var/lib/nfs

[Sylvain Beucler <beuc@beuc.net>]

Hi,

I submitted the following patch to address this issue:
https://salsa.debian.org/debian/nfs-utils/merge_requests/3/diffs

The source part of the fix was also submitted at:
https://bugzilla.linux-nfs.org/show_bug.cgi?id=338

I intend to push it to LTS/ELTS, I can also prepare an upload for
stable/oldstable if security-team wishes so.
What do you think?

To test:

pp/post_install_checknfs.sh:

#!/bin/sh -ex
if [ -e /var/lib/nfs ]; then
    ls -ld /var/lib/nfs
    if [ "$(dpkg -l | grep ' nfs-common ' | awk '{print $3}')" !=
'1:1.3.4-2.6' ]; then
        exit 0
    fi
    if [ "$(stat -c '%U:%G' /var/lib/nfs)" != 'root:root' ]; then
        exit 1
    fi
fi

sudo piuparts -d bullseye nfs-utils_1.3.4-2.6_amd64.changes
--scriptsdir=$(pwd)/pp
sudo piuparts -d bullseye nfs-utils_1.3.4-2.6_amd64.changes
--scriptsdir=$(pwd)/pp --install-remove-install


Mount NFS with v3 mode to force statd:
$ sudo service rpcinfo stop
$ sudo service rpcinfo start
$ sudo mount -t nfs -o vers=3 127.0.0.1:/media/nfs /mnt/t
$ ps aux | grep statd
Ensure rpc.statd runs as 'statd' (not 'root').

Cheers!
Sylvain Beucler
Debian LTS Team