From: Daniel Axtens <dja@axtens•net>
To: Andrew Donnellan <ajd@linux•ibm.com>,
Christopher M Riedl <cmr@informatik•wtf>,
linuxppc-dev@ozlabs•org, kernel-hardening@lists•openwall.com
Cc: mjg59@google•com
Subject: Re: [RFC PATCH v2] powerpc/xmon: restrict when kernel is locked down
Date: Mon, 29 Jul 2019 17:00:38 +1000 [thread overview]
Message-ID: <87ef29gwa1.fsf@dja-thinkpad.axtens.net> (raw)
In-Reply-To: <87h88m2iu4.fsf@dja-thinkpad.axtens.net>
Hi Chris,
>>>> Remind me again why we need to clear breakpoints in integrity mode?
...
>> Integrity mode merely means we are aiming to prevent modifications to
>> kernel memory. IMHO leaving existing breakpoints in place is fine as
>> long as when we hit the breakpoint xmon is in read-only mode.
>>
...
> I think ajd is right.
>
> I think about it like this. There are 2 transitions:
>
> - into integrity mode
>
> Here, we need to go into r/o, but do not need to clear breakpoints.
> You can still insert breakpoints in readonly mode, so clearing them
> just makes things more irritating rather than safer.
>
> - into confidentiality mode
>
> Here we need to purge breakpoints and disable xmon completely.
Would you be able to send a v2 with these changes? (that is, not purging
breakpoints when entering integrity mode)
Regards,
Daniel
next prev parent reply other threads:[~2019-07-29 7:03 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-24 12:38 [RFC PATCH v2] powerpc/xmon: restrict when kernel is locked down Christopher M. Riedl
2019-06-03 5:36 ` Andrew Donnellan
2019-06-04 3:05 ` Christopher M Riedl
2019-06-04 3:28 ` Andrew Donnellan
2019-06-19 6:24 ` Daniel Axtens
2019-07-29 7:00 ` Daniel Axtens [this message]
2019-08-03 19:04 ` Christopher M Riedl
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