linux-kernel - Re: [PATCH v6 05/14] x86: Secure Launch main header file

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Date:   Tue, 31 Oct 2023 17:37:47 -0400
From:   ross.philipson@...cle.com
To:     Matthew Garrett <mjg59@...f.ucam.org>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        linux-integrity@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-crypto@...r.kernel.org, iommu@...ts.linux-foundation.org,
        kexec@...ts.infradead.org, linux-efi@...r.kernel.org,
        dpsmith@...rtussolutions.com, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, hpa@...or.com, ardb@...nel.org,
        James.Bottomley@...senpartnership.com, luto@...capital.net,
        nivedita@...m.mit.edu, kanth.ghatraju@...cle.com,
        trenchboot-devel@...glegroups.com
Subject: Re: [PATCH v6 05/14] x86: Secure Launch main header file

On 5/12/23 9:10 AM, Ross Philipson wrote:
> On 5/12/23 07:00, Matthew Garrett wrote:
>> On Thu, May 04, 2023 at 02:50:14PM +0000, Ross Philipson wrote:
>>
>>> +static inline int tpm12_log_event(void *evtlog_base, u32 evtlog_size,
>>> +                  u32 event_size, void *event)
>>> +{
>>> +    struct tpm12_event_log_header *evtlog =
>>> +        (struct tpm12_event_log_header *)evtlog_base;
>>> +
>>> +    if (memcmp(evtlog->signature, TPM12_EVTLOG_SIGNATURE,
>>> +           sizeof(TPM12_EVTLOG_SIGNATURE)))
>>> +        return -EINVAL;
>>> +
>>> +    if (evtlog->container_size > evtlog_size)
>>> +        return -EINVAL;
>>> +
>>> +    if (evtlog->next_event_offset + event_size > 
>>> evtlog->container_size)
>>> +        return -E2BIG;
>>> +
>>> +    memcpy(evtlog_base + evtlog->next_event_offset, event, event_size);
>>> +    evtlog->next_event_offset += event_size;
>>> +
>>> +    return 0;
>>> +}
>>> +
>>> +static inline int tpm20_log_event(struct 
>>> txt_heap_event_log_pointer2_1_element *elem,
>>> +                  void *evtlog_base, u32 evtlog_size,
>>> +                  u32 event_size, void *event)
>>> +{
>>> +    struct tcg_pcr_event *header =
>>> +        (struct tcg_pcr_event *)evtlog_base;
>>> +
>>> +    /* Has to be at least big enough for the signature */
>>> +    if (header->event_size < sizeof(TCG_SPECID_SIG))
>>> +        return -EINVAL;
>>> +
>>> +    if (memcmp((u8 *)header + sizeof(struct tcg_pcr_event),
>>> +           TCG_SPECID_SIG, sizeof(TCG_SPECID_SIG)))
>>> +        return -EINVAL;
>>> +
>>> +    if (elem->allocated_event_container_size > evtlog_size)
>>> +        return -EINVAL;
>>> +
>>> +    if (elem->next_record_offset + event_size >
>>> +        elem->allocated_event_container_size)
>>> +        return -E2BIG;
>>> +
>>> +    memcpy(evtlog_base + elem->next_record_offset, event, event_size);
>>> +    elem->next_record_offset += event_size;
>>> +
>>> +    return 0;
>>> +}
>>> +
>>
>> These seem like they'd potentially be useful outside the context of SL,
>> maybe put them in a more generic location? Very much a nice to have, not
>> a blocker from my side.
> 
> Yea we can look into finding a nice home somewhere in the TPM event log 
> code for these.

After looking at it, it seems we would have to drag a whole bunch of TXT 
related structures into the TPM event log code. I don't think this is 
really worth it for what these functions do.

Thanks
Ross

> 
>>
>>> +/*
>>> + * External functions avalailable in mainline kernel.
>>
>> Nit: "available"
> 
> Ack
> 
> Thanks
> 
>>
>