[PATCH] audit: do not panic kernel on invalid audit parameter

[Greg Edwards]

On Tue, Feb 20, 2018 at 04:45:26PM -0500, Paul Moore wrote:
> On Tue, Feb 20, 2018 at 4:33 PM, Greg Edwards <gedwards at ddn.com> wrote:
>> If you pass in an invalid audit kernel boot parameter, e.g. 'audit=off',
>> the kernel panics very early in boot with no output on the console
>> indicating the problem.
>
> I'm guessing the problem is that there was too much info dumped to the
> console and the error message was lost (there is one, to say there is
> "no output" isn't completely correct), is that what happened?  Or was
> there honestly *no* output on the console?

Booting a 4.16-rc2 VM with defconfig + kvmconfig with the 'audit=off'
boot parameter (my mistake), the only output you get is:

.

Not terribly enlightening.

>> This seems overly harsh.  Instead, print the error indicating an invalid
>> audit parameter value and leave auditing disabled.
>
> There are some audit requirements which appear rather bizarre at
> times, e.g. the need to panic the kernel instead of losing an audit
> event.  Steve is the one who follows most of these audit requirements
> so I'm going to wait until he has a chance to look at this.
>
> There is also another issue in this patch, on error you have the audit
> subsystem default to off, we may want to change this to default to on
> in case of error (fail safely).

Sure, that is fine.  I just took a stab at what to do for the error
case.  I'm happy to default it to enabled, if that would be more
appropriate.

Greg