Messages in this thread | | | From | Lakshmi Ramasubramanian <> | Subject | RE: Portable Executable (PE) Signature Validation and Measurement for KEXEC system call using IMA | Date | Mon, 25 Mar 2019 21:00:36 +0000 |
| |
Thanks for your response Mimi.
Please see my responses to your queries inline.
Thanks, -lakshmi
>-----Original Message----- >From: Mimi Zohar <zohar@linux.ibm.com> >Sent: Monday, March 25, 2019 12:28 PM >To: Lakshmi Ramasubramanian <nramas@microsoft.com>; linux-integrity@vger.kernel.org; linux-kernel@vger.kernel.org >Subject: Re: Portable Executable (PE) Signature Validation and Measurement for KEXEC system call using IMA
>Hi Lakshmi,
>On Fri, 2019-03-22 at 17:39 +0000, Lakshmi Ramasubramanian wrote: >> Hello, >> >> When loading the new kernel image file for executing KEXEC system call, >> we would like to verify that the kernel image file is signed and >> the signer certificate is valid. >>
> I'm not sure what is meant by "and the signer certificate is valid".
> The kexec kernel image signature can be verified by keys either on the > IMA keyring or the platform keyring. The current method of verifying > keys being added to the IMA keyring is by requiring them to be signed > by a key on the builtin trusted keyring. This provides a signature > chain of trust from boot to the kernel, based on a HW root of trust, > and then transitions to the kernel image's embedded keys. You > probably already know as to why/how the platform keys are trusted.
[Lakshmi] By "signer certificate is valid" I meant, the key used to sign the kexec kernel image is trusted. We will verify the signature using the key in the IMA keyring (like the way you have described above)
>> >> If the kernel image file is in Portable Executable (PE) format we want to >> validate the PE Signature and measure the signer X.509 certificate >> (Extend as part of IMA Template defaulting to PCR 10, if not otherwise set, >> and the IMA measurement log).
> How/when do you plan to "measure the signer X.509 certificate"? Is > this when the certificate is being loaded onto the keyring or at use? > I'm not sure how much of the certificate is available once loaded > onto the keyring.
[Lakshmi] We will measure the signer certificate when the file is loaded - in other words, "at use". The kernel image signer information measured in to the IMA log will then be used as one of the attestation criteria.
>> >> We plan to use Integrity Measurement Architecture (IMA) for the above. >> >> Please let us know if anyone is already working on a patch set >> for such a functionality. >> >> I am aware of the work that Thiago Jung Bauermann @ IBM is doing for >> "Appended signatures support for IMA appraisal" >> (Web link given below) >> >> https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Flkml.org%2Flkml%2F2018%2F12%2F12%2F1049&data=02%7C01%7Cnramas%40microsoft.com%7Cc36d42cb91214cc3ca1308d6b157f962%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636891388745548879&sdata=OLtkuptXQYZHuvlVmn3ej%2FpEk501TxzToEcbOref0UU%3D&reserved=0
> Other than Thiago, I'm not aware of anyone else working on this. > Thiago is actively working on these patches and will be re-posting > them shortly.
[Lakshmi] Thanks for the information.
> Mimi
Thanks, -lakshmi
| |