We're running Sophos Protection for Linux Server (SPL) with MTR and InterceptX. We're running it across many Ubuntu 20.04 LTS servers (OS and apps are fully updated). We're also running Veeam Backup & Replication (VBR) with Veeam Agent for Linux (VAL) installed on all Ubuntu servers.
On our Ubuntu Linux servers, our Veeam backup software creates temporary filesystems similar to the following:
and mounts it as /dev/veeamimage0.
The hex string between the brackets is different for each backup session. At the end of the backup session, the temporary filesystem is emptied and unmounted. However, Sophos SPL appears to be doing something to "lock" the above filesystem and is preventing it from being unmounted at the end of the backup session. This is causing the backup session to fail. This is a big problem for us, and is impacting many production servers.
Our question is this: Is SPL doing something to lock down certain filesystems to prevent them from being unmounted, and if so, how can we exempt a specific filesystem so that Sophos does not lock it down?
This does NOT seem to be related to AV exceptions, as the above filesystem is already exempted from AV (wildcard exception added in Sophos Central). The problem seems to be due to something else that SPL is doing.
We've demonstrated that Sophos SPL is the cause of this problem by running the following test across multiple servers:
a. While SPL is running, any attempt to unmount the Veeam temp filesystem fails.
b. After stopping SPL, unmounting the Veeam temp filesystem succeeds without any issues.
So this seems to suggest that SPL is placing some kind of lock on the Veeam temp filesystem, and this is preventing Veeam from unmounting the temp filesystem. That is causing each server backup to fail.
Since we do not understand the inside workings of all of the SPL modules/features, we're hoping that you might have some insight into why SPL is locking the above-mentioned temporary filesystems?
We've tried using lsof and fuser to identify the offending process, but strangely nothing is showing up. Our working theory is that Sophos SPL is doing something to "lock" the above filesystem, and is thereby preventing it from being unmounted. But we cannot figure out WHAT exactly Sophos SPL is doing that is resulting in this issue.
Thank you in advance!
[edited by: Gladys at 7:35 AM (GMT -8) on 1 Dec 2022]