Auditd doesn't receive syscalls after installation for the current shell.

[Paul Moore]

On Wed, May 24, 2023 at 10:46 AM Steve Grubb <sgrubb at redhat.com> wrote:
> On Wednesday, May 24, 2023 7:37:27 AM EDT Rinat Gadelshin wrote:
> > Hello there.
> >
> > It seems that the kernel doesn't send messages for syscalls of the shell
> > process from which auditd is installed.
> >
> > Reproducing steps (performed on Ubuntu 22.04 x86_64 on virtual box by
> > `root`):
> >
> > step #1: $ apt install auditd
> > step #2: $ auditctl -a always,exit -F arch=b64 -S openat,renameat2,unlinkat
> > step #3: $ echo t>delme;echo t2>>delme;cat delme;mv delme d;mv d
> > delme;rm delme
> > step #4: $ service auditd stop
> > step #5: $ ausearch -f delme
> >
> > There are syscalls from /usr/bin/cat, /usr/bin/mv, /usr/bin/rm but there
> > are no any syscalls (openat expected)
> > for /usr/bin/bash (current shell process) for the file.
> >
> > If step #3 is performed from another tty, then openat syscalls
> > (CREATE for the first echo and NORMAL for the second one)
> > is logged for the /usr/bin/bash process.
> >
> > `uname -a` returns: Linux grin-vb-ubuntu-22-0-4 5.19.0-41-generic
> > #42~22.04.01-Ubuntu SMP PREEMPT_DYNAMIC Tue Apr 18 17:40:00 UTC 2 x86_64
> > x86_64 x86_64 GNU/Linux
> >
> > Should I open an issue for the case at
> > https://github.com/linux-audit/audit-kernel ?
>
> Are you booting with audit=1 ? If not, the install process and any before it
> are not auditable. You will only get events for processes started after audit
> enabled = 1.

It is also worth noting that some distributions (I'm not sure if this
applies to Ubuntu) effectively limit auditing with their default
runtime configuration, see the wiki page below for more information:

* https://github.com/linux-audit/audit-documentation/wiki/HOWTO-Fedora-Enable-Auditing

-- 
paul-moore.com