linux-kernel - Re: Regression from efi: call get_event

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Date:   Mon, 12 Mar 2018 17:01:01 +0000
From:   Jeremy Cline <jeremy@...ine.org>
To:     Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc:     Thiebaud Weksteen <tweek@...gle.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Javier Martinez Canillas <javierm@...hat.com>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        linux-efi@...r.kernel.org, linux-integrity@...r.kernel.org,
        tpmdd-devel@...ts.sourceforge.net,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Regression from efi: call get_event_log before ExitBootServices

On 03/12/2018 10:56 AM, Ard Biesheuvel wrote:
> On 12 March 2018 at 14:30, Jeremy Cline <jeremy@...ine.org> wrote:
>> On 03/12/2018 07:08 AM, Ard Biesheuvel wrote:
>>> On 10 March 2018 at 10:45, Thiebaud Weksteen <tweek@...gle.com> wrote:
>>>> On Fri, Mar 9, 2018 at 5:54 PM Jeremy Cline <jeremy@...ine.org> wrote:
>>>>
>>>>> On Fri, Mar 09, 2018 at 10:43:50AM +0000, Thiebaud Weksteen wrote:
>>>>>> Thanks a lot for trying out the patch!
>>>>>>
>>>>>> Please don't modify your install at this stage, I think we are hitting a
>>>>>> firmware bug and that would be awesome if we can fix how we are
>>>> handling it.
>>>>>> So, if we reach that stage in the function it could either be that:
>>>>>> * The allocation did not succeed, somehow, but the firmware still
>>>> returned
>>>>>> EFI_SUCCEED.
>>>>>> * The size requested is incorrect (I'm thinking something like a 1G of
>>>>>> log). This would be due to either a miscalculation of log_size
>>>> (possible)
>>>>>> or; the returned values of GetEventLog are not correct.
>>>>>> I'm sending a patch to add checks for these. Could you please apply and
>>>>>> retest?
>>>>>> Again, thanks for helping debugging this.
>>>>
>>>>> No problem, thanks for the help :)
>>>>
>>>>> With the new patch:
>>>>
>>>>> Locating the TCG2Protocol
>>>>> Calling GetEventLog on TCG2Protocol
>>>>> Log returned
>>>>> log_location is not empty
>>>>> log_size != 0
>>>>> log_size < 1M
>>>>> Allocating memory for storing the logs
>>>>> Returned from memory allocation
>>>>> Copying log to new location
>>>>
>>>>> And then it hangs. I added a couple more print statements:
>>>>
>>>>> diff --git a/drivers/firmware/efi/libstub/tpm.c
>>>> b/drivers/firmware/efi/libstub/tpm.c
>>>>> index ee3fac109078..1ab5638bc50e 100644
>>>>> --- a/drivers/firmware/efi/libstub/tpm.c
>>>>> +++ b/drivers/firmware/efi/libstub/tpm.c
>>>>> @@ -148,8 +148,11 @@ void
>>>> efi_retrieve_tpm2_eventlog_1_2(efi_system_table_t *sys_table_arg)
>>>>>          efi_printk(sys_table_arg, "Copying log to new location\n");
>>>>
>>>>>          memset(log_tbl, 0, sizeof(*log_tbl) + log_size);
>>>>> +       efi_printk(sys_table_arg, "Successfully memset log_tbl to 0\n");
>>>>>          log_tbl->size = log_size;
>>>>> +       efi_printk(sys_table_arg, "Set log_tbl->size\n");
>>>>>          log_tbl->version = EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2;
>>>>> +       efi_printk(sys_table_arg, "Set log_tbl-version\n");
>>>>>          memcpy(log_tbl->log, (void *) first_entry_addr, log_size);
>>>>
>>>>>          efi_printk(sys_table_arg, "Installing the log into the
>>>> configuration table\n");
>>>>
>>>>> and it's hanging at "memset(log_tbl, 0, sizeof(*log_tbl) + log_size);"
>>>>
>>>> Thanks. Well, it looks like the memory that is supposedly allocated is not
>>>> usable. I'm thinking this is a firmware bug.
>>>> Ard, would you agree on this assumption? Thoughts on how to proceed?
>>>>
>>>
>>> I am rather puzzled why the allocate_pool() should succeed and the
>>> subsequent memset() should fail. This does not look like an issue that
>>> is intimately related to TPM2 support, rather an issue in the firmware
>>> that happens to get tickled after the change.
>>>
>>> Would you mind trying replacing EFI_LOADER_DATA with
>>> EFI_BOOT_SERVICES_DATA in the allocate_pool() call?
>>
>> Replacing EFI_LOADER_DATA with EFI_BOOT_SERVICES_DATA still hangs at the
>> memset() call.
>>
> 
> Could you try the following please? (attached as well in case gmail mangles it)
> 
> diff --git a/drivers/firmware/efi/libstub/tpm.c
> b/drivers/firmware/efi/libstub/tpm.c
> index 2298560cea72..30d960a344b7 100644
> --- a/drivers/firmware/efi/libstub/tpm.c
> +++ b/drivers/firmware/efi/libstub/tpm.c
> @@ -70,6 +70,8 @@ void
> efi_retrieve_tpm2_eventlog_1_2(efi_system_table_t *sys_table_arg)
>         size_t log_size, last_entry_size;
>         efi_bool_t truncated;
>         void *tcg2_protocol;
> +       unsigned long num_pages;
> +       efi_physical_addr_t log_tbl_alloc;
> 
>         status = efi_call_early(locate_protocol, &tcg2_guid, NULL,
>                                 &tcg2_protocol);
> @@ -104,9 +106,12 @@ void
> efi_retrieve_tpm2_eventlog_1_2(efi_system_table_t *sys_table_arg)
>         }
> 
>         /* 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);
> +       num_pages = DIV_ROUND_UP(sizeof(*log_tbl) + log_size, EFI_PAGE_SIZE);
> +       status = efi_call_early(allocate_pages,
> +                               EFI_ALLOCATE_ANY_PAGES,
> +                               EFI_LOADER_DATA,
> +                               num_pages,
> +                               &log_tbl_alloc);
> 
>         if (status != EFI_SUCCESS) {
>                 efi_printk(sys_table_arg,
> @@ -114,6 +119,7 @@ void
> efi_retrieve_tpm2_eventlog_1_2(efi_system_table_t *sys_table_arg)
>                 return;
>         }
> 
> +       log_tbl = (struct linux_efi_tpm_eventlog *)(unsigned long)log_tbl_alloc;
>         memset(log_tbl, 0, sizeof(*log_tbl) + log_size);
>         log_tbl->size = log_size;
>         log_tbl->version = EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2;
> @@ -126,7 +132,7 @@ void
> efi_retrieve_tpm2_eventlog_1_2(efi_system_table_t *sys_table_arg)
>         return;
> 
>  err_free:
> -       efi_call_early(free_pool, log_tbl);
> +       efi_call_early(free_pages, log_tbl_alloc, num_pages);
>  }
> 
>  void efi_retrieve_tpm2_eventlog(efi_system_table_t *sys_table_arg)
> 

Hi Ard,

When I apply this, it starts hanging at

status = efi_call_proto(efi_tcg2_protocol, get_event_log, tcg2_protocol,
                        EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2,
                        &log_location, &log_last_entry, &truncated);

rather than at the memset() call.

Regards,
Jeremy