Red Hat Bugzilla – Bug 1464270
PrivateTmp = true breaks all ScanOnAccess features
Last modified: 2018-01-07 21:01:12 EST
+++ This bug was initially created as a clone of Bug #1464269 +++
"PrivateTmp = true" was added to the clamd@.service unit file per request of Dan Walsh in bug 782488.
Since version 0.99, Clam AntiVirus has been able to use fanotify() in order to provide on-access scanning:
Unfortunately, using "PrivateTmp = true" silently breaks all on-access scanning features. Not only does on-access scanning for /tmp and /var/tmp not work (because the clamd service is not looking at the real /tmp and /var/tmp directories), but all other uses of OnAccessIncludePath and OnAccessMountPath silently fail as well.
This is trivial to test. As root:
$ cat >/etc/clamd.d/root.conf <<EOF
$ systemctl start clamd@root
As a regular user, cd to your home directory, and do:
$ cat >/home/testuser/eicar.com <<EOF
Result: the clamd daemon will not receive a fanotify event, and therefore will not detect the creation of the test virus file.
Now turn off the PrivateTmp feature. As root:
$ cat >/etc/systemd/system/clamd@.service
PrivateTmp = false
$ systemctl daemon-reload
$ systemctl restart clamd@root
As the regular user, cat the eicar.com test file:
$ cat eicar.com
Now, the clam daemon will receive the fanotify event, and emit something like this:
2017-06-22T16:41:41.758517-04:00 host.example.org clamd: ScanOnAccess: /home/testuser/eicar.com: Eicar-Test-Signature(69630e4574ec6798239b091cda43dca0:69) FOUND
While in general, "PrivateTmp = true" is a good idea, it *MUST NOT* be used with clamav, because a service with PrivateTmp = true will never receive any fanotify() events, which breaks clamav core functionality.
Please remove the "PrivateTmp = true" line from the clamd@.service file.
*** This bug has been marked as a duplicate of bug 1464269 ***