Otdfbt

I have a symbolic link of the form

ubuntu@platform1:~$ ls -lrt
total 28
drwxr-xr-x 4 ubuntu ubuntu 4096 Mar 2 15:02 deploy
lrwxrwxrwx 1 ubuntu ubuntu 14 May 25 18:27 logs -> /var/log/arkin

Disk layout

ubuntu@platform1:~$ df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg-var 853G 3.7G 806G 1% /var
/dev/mapper/vg-var+log 49G 1.1G 45G 3% /var/log
/dev/mapper/vg-var+log+audit 20G 60M 19G 1% /var/log/audit
/dev/mapper/vg-home 30G 6.5G 22G 24% /home

But many times I am observing that symbolic link is changed to

drwxr-xr-x 6 ubuntu ubuntu 4096 May 31 08:41 logs

Can someone let me know if there is a way to enable audit logs on the folder /home/ubuntu/logs so that I can get some idea which operation is breaking the symbolic link and creating a new /home/ubuntu/logs or some other ways I can debug this problem?

• Filesystem - ext4


• OS - Ubuntu 16.04

EDIT

I followed the steps as suggested in the answer. I had the following symbolic link :-

lrwxrwxrwx 1 ubuntu ubuntu 14 Jun 3 07:26 logs -> /var/log/arkin

Added the below rule in /etc/audit/audit.rules

-a always,exit -F dir=/home/ubuntu/logs -S unlink -S unlinkat -S rename -S renameat -S rmdir -k log_link

Then restarted audit service

ubuntu@vrni-platform:~$ sudo service auditd stop
ubuntu@vrni-platform:~$ sudo service auditd start

Executed the below command

ubuntu@vrni-platform:~$ sudo ln -svf /var/log/arkin /home/ubuntu/logs
'/home/ubuntu/logs/arkin' -> '/var/log/arkin'

But I am not seeing any audit entry

# aureport -k -i | grep log_link

For auditd you can try below

$tail -2 /etc/audit/audit.rules 
-a always,exit -F arch=b32 -S unlink -S unlinkat -S rename -S renameat -S rmdir -k delete
-a always,exit -F arch=b64 -S unlink -S unlinkat -S rename -S renameat -S rmdir -k delete

Here you can specify directory too

-F dir=<directory or mount point>

Here is the used options description in shot for more details please check http://man7.org/linux/man-pages/man8/auditctl.8.html

 -a [list,action|action,list] 
 -S [Syscall name or number|all]
 -k key Set a filter key on an audit rule.

Some more examples for different rules are:

## Audit log access
-a always,exit -F dir=/var/log/audit/ -F perm=r -F auid>=1000 -F auid!=unset -F key=access-audit-trail
## Attempts to Alter Process and Session Initiation Information
-a always,exit -F path=/var/run/utmp -F perm=wa -F auid>=1000 -F auid!=unset -F key=session
-a always,exit -F path=/var/log/btmp -F perm=wa -F auid>=1000 -F auid!=unset -F key=session
-a always,exit -F path=/var/log/wtmp -F perm=wa -F auid>=1000 -F auid!=unset -F key=session