Message-ID: <010001621b7a26a3-00b03675-ef19-4b76-9ace-5b6fdc59d441-000000@email.amazonses.com>
Date:   Mon, 12 Mar 2018 18:30:13 +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 01:30 PM, Ard Biesheuvel wrote:
> On 12 March 2018 at 17:01, Jeremy Cline <jeremy@...ine.org> wrote:
>> 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.
>>
> 
> That is *very* surprising, given that the change only affects code
> that executes after that.

Yeah, I triple-checked because I was so surprised.

> I understand how annoying this is for you, and I think we should try
> to fix this, but reverting the patches outright isn't the solution
> either.

Completely understandable and I'm not the least bit annoyed :)

In case you missed it, Hans has the exact same tablet (I got this one
from him) and he can't reproduce it, but the one he sent me isn't using
shim and has a RHEL build of grub. At Thiebaud's request I didn't change
anything about the setup, but I'm guessing if I restore it to use the
Fedora setup the problem won't appear. I'm happy to make a backup and
verify this hypothesis.

> 
> Which UEFI vendor and version does your system report?
> 

It's InsydeH20 version BYT70A.YNCHENG.WIN.007

Regards,
Jeremy

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