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From: Thiebaud Weksteen <tweek-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
To: Javier Martinez Canillas
	<javierm-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Cc: linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Ard Biesheuvel
	<ard.biesheuvel-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>,
	Matt Fleming
	<matt-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Matthew Garrett <mjg59-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
	Jason Gunthorpe
	<jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>,
	tpmdd-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org,
	jarkko.sakkinen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org,
	Peter Jones <pjones-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Subject: Re: [tpmdd-devel] [PATCH v2 2/3] efi: call get_event_log before ExitBootServices
Date: Mon, 18 Sep 2017 14:11:23 +0200	[thread overview]
Message-ID: <CA+zpnLfewoD7H1hZzCnVKi09a6+DvfGY8ZhFTYuKKFTBgSgoOA@mail.gmail.com> (raw)
In-Reply-To: <1f25ebdc-ab90-517f-b580-991a7cb5e25a-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>

On Thu, Sep 14, 2017 at 12:24 PM, Javier Martinez Canillas
<javierm-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
> On 09/11/2017 12:00 PM, Thiebaud Weksteen via tpmdd-devel wrote:
>> With TPM 2.0 specification, the event logs may only be accessible by
>> calling an EFI Boot Service. Modify the EFI stub to copy the log area to
>> a new Linux-specific EFI configuration table so it remains accessible
>> once booted.
>>
>> When calling this service, it is possible to specify the expected format
>> of the logs: TPM 1.2 (SHA1) or TPM 2.0 ("Crypto Agile"). For now, only the
>> first format is retrieved.
>>
>> Signed-off-by: Thiebaud Weksteen <tweek-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
>> ---
>
> [snip]
>
>> +void efi_retrieve_tpm2_eventlog_1_2(efi_system_table_t *sys_table_arg)
>> +{
>
> [snip]
>
>> +
>> +     /* Allocate space for the logs and copy them. */
>> +     status = efi_call_early(allocate_pool, EFI_LOADER_DATA,
>> +                             sizeof(*log_tbl) + log_size,
>> +                             (void **) &log_tbl);
>> +
>> +     if (status != EFI_SUCCESS) {
>> +             efi_printk(sys_table_arg,
>> +                        "Unable to allocate memory for event log\n");
>> +             return;
>> +     }
>
> If this fails or any previous error that will prevent the event log table + logs
> to be allocated, shouldn't tpm_read_log_efi() be notified somehow? Since AFAICT
> it will still try to access them even if the EFI allocate_pool did not succeed.
>

The implicit part that covers this case is in
drivers/firmware/efi/efi.c. The match_config_table function will go
through all the installed configuration tables and only fill up the
associated member of the efi structure if it exists. In this case,
.tpm_log will remains at EFI_INVALID_TABLE_ADDR unless
efi_call_early(install_configuration_table, ...) is called. So no
further processing is to be expected should the allocation failed.

>> + */
>> +int __init efi_tpm_eventlog_init(void)
>> +{
>> +     struct linux_efi_tpm_eventlog *tbl;
>> +     unsigned int tbl_size;
>> +
>
> The functions efi_retrieve_tpm2_eventlog_1_2() and tpm_read_log_efi() are using
> log_tbl as variable name, so I would use it here too for consistency.
>

Done.

>> +     if (efi.tpm_log == EFI_INVALID_TABLE_ADDR)
>> +             return 0;
>> +
>> +     tbl = early_memremap(efi.tpm_log, sizeof(*tbl));
>> +     if (!tbl) {
>> +             pr_err("Failed to map TPM Event Log table @ 0x%lx\n",
>> +                     efi.tpm_log);
>> +             return -ENOMEM;
>> +     }
>> +
>
> Same question than before, if this fails then the table + logs memory won't be
> reserved but tpm_read_log_efi() will still try to access it. I'm not sure what
> is the correct way to notify though, maybe setting efi.tpm_log to 0 and then in
> tpm_read_log_efi() check efi.tpm_log for 0 or EFI_INVALID_TABLE_ADDR instead?
>

That's right. To keep it simple, it might be easier to just set
tpm_log to EFI_INVALID_TABLE_ADDR if that happens. Added in the next
version of the patch set.

>> +     tbl_size = sizeof(*tbl) + tbl->size;
>> +     memblock_reserve(efi.tpm_log, tbl_size);
>> +     early_memunmap(tbl, sizeof(*tbl));
>> +     return 0;
>
> Best regards,
> --
> Javier Martinez Canillas
> Software Engineer - Desktop Hardware Enablement
> Red Hat

  parent reply	other threads:[~2017-09-18 12:11 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-09-11 10:00 [PATCH v2 0/3] Call GetEventLog " Thiebaud Weksteen
2017-09-11 10:00 ` [PATCH v2 1/3] tpm: move tpm_eventlog.h outside of drivers folder Thiebaud Weksteen
2017-09-11 10:00 ` [PATCH v2 2/3] efi: call get_event_log before ExitBootServices Thiebaud Weksteen
     [not found]   ` <20170911100022.7251-3-tweek-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2017-09-13 14:49     ` kbuild test robot
     [not found]       ` <201709132252.uZyTCtDz%fengguang.wu-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
2017-09-13 16:28         ` Thiebaud Weksteen via tpmdd-devel
2017-09-14 10:24     ` [tpmdd-devel] " Javier Martinez Canillas
     [not found]       ` <1f25ebdc-ab90-517f-b580-991a7cb5e25a-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2017-09-18 12:11         ` Thiebaud Weksteen [this message]
2017-09-18 12:49           ` Javier Martinez Canillas
2017-09-14 18:43     ` Jarkko Sakkinen
     [not found]       ` <20170914184126.eevnstwq3i6fiq4j-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2017-09-14 18:48         ` Matthew Garrett
2017-09-14 19:02           ` Jarkko Sakkinen
     [not found]             ` <20170914190247.rrbdzdexjjywxipf-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2017-09-15  4:06               ` Jarkko Sakkinen
2017-09-18 12:28               ` Thiebaud Weksteen
     [not found]                 ` <CA+zpnLfs=DhW6kgbLV63_XzmKS7VnGGE0ecbFBZ0bu4wx3Jf+w-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-09-18 17:56                   ` Jarkko Sakkinen
2017-09-11 10:00 ` [PATCH v2 3/3] tpm: parse TPM event logs based on EFI table Thiebaud Weksteen
     [not found]   ` <20170911100022.7251-4-tweek-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2017-09-11 16:47     ` Jason Gunthorpe
2017-09-12  8:48       ` Thiebaud Weksteen
     [not found]         ` <20170912084851.z3ednbeojawnyxk2-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2017-09-18 12:38           ` Thiebaud Weksteen
2017-09-18 16:28             ` Jason Gunthorpe
2017-09-13 16:27     ` kbuild test robot
     [not found]       ` <201709140034.ESdZA8H8%fengguang.wu-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
2017-09-13 16:43         ` Thiebaud Weksteen
2017-09-14 18:47   ` Jarkko Sakkinen
     [not found]     ` <20170914184732.uiypaz4yft777oc7-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2017-09-18 12:33       ` Thiebaud Weksteen
     [not found] ` <20170911100022.7251-1-tweek-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2017-09-13 18:59   ` [PATCH v2 0/3] Call GetEventLog before ExitBootServices Jarkko Sakkinen
2017-11-03 15:27   ` Jarkko Sakkinen
2017-09-14 10:21 ` [tpmdd-devel] " Javier Martinez Canillas

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