Re: [RFC PATCH v19 1/5] exec: Add a new AT_CHECK flag to execveat(2)

Florian Weimer <[email protected]> Mon, 08 Jul 2024 19:33:03 +0200

Newsgroups	com.openwall.lists.kernel-hardening,org.kernel.vger.linux-api,org.kernel.vger.linux-fsdevel,org.kernel.vger.linux-integrity,org.kernel.vger.linux-kernel,org.kernel.vger.linux-security-module
Message-ID	<[email protected]>

* Jeff Xu:

> On Mon, Jul 8, 2024 at 9:26 AM Florian Weimer <[email protected]> wrote:
>>
>> * Jeff Xu:
>>
>> > Will dynamic linkers use the execveat(AT_CHECK) to check shared
>> > libraries too ?  or just the main executable itself.
>>
>> I expect that dynamic linkers will have to do this for everything they
>> map.
> Then all the objects (.so, .sh, etc.) will go through  the check from
> execveat's main  to security_bprm_creds_for_exec(), some of them might
> be specific for the main executable ?

If we want to avoid that, we could have an agreed-upon error code which
the LSM can signal that it'll never fail AT_CHECK checks, so we only
have to perform the extra system call once.

Thanks,
Florian