Messages in this thread | | | Date | Thu, 18 Nov 2021 10:30:32 -0800 | Subject | Re: [PATCH v2 0/2] Introduce the pkill_on_warn parameter | From | Casey Schaufler <> |
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On 11/18/2021 9:32 AM, Kees Cook wrote: > On Tue, Nov 16, 2021 at 11:00:23AM -0800, Casey Schaufler wrote: >> On 11/16/2021 10:41 AM, Kees Cook wrote: >>> On Tue, Nov 16, 2021 at 12:12:16PM +0300, Alexander Popov wrote: >>>> What if the Linux kernel had a LSM module responsible for error handling policy? >>>> That would require adding LSM hooks to BUG*(), WARN*(), KERN_EMERG, etc. >>>> In such LSM policy we can decide immediately how to react on the kernel error. >>>> We can even decide depending on the subsystem and things like that. >>> That would solve the "atomicity" issue the WARN tracepoint solution has, >>> and it would allow for very flexible userspace policy. >>> >>> I actually wonder if the existing panic_on_* sites should serve as a >>> guide for where to put the hooks. The current sysctls could be replaced >>> by the hooks and a simple LSM. >> Do you really want to make error handling a "security" issue? >> If you add security_bug(), security_warn_on() and the like >> you're begging that they be included in SELinux (AppArmor) policy. >> BPF, too, come to think of it. Is that what you want? > Yeah, that is what I was thinking. This would give the LSM a view into > kernel state, which seems a reasonable thing to do. If system integrity > is compromised, an LSM may want to stop trusting things.
How are you planning to communicate the security relevance of the warning to the LSM? I don't think that __FILE__, __LINE__ or __func__ is great information to base security policy on. Nor is a backtrace.
> A dedicated error-handling LSM could be added for those hooks that > implemented the existing default panic_on_* sysctls, and could expand on > that logic for other actions.
I can see having an interface like LSM for choosing a bug/warn policy. I worry about expanding the LSM hook list for a case where I would hope no existing LSM would use them, and the new LSM doesn't use any of the existing hooks.
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