Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Luis R. Rodriguez]

On Tue, May 08, 2018 at 03:38:05PM +, Luis R. Rodriguez wrote:
> On Fri, May 04, 2018 at 12:44:37PM -0700, Martijn Coenen wrote:
> > On Wed, Apr 25, 2018 at 10:55 AM, Luis R. Rodriguez  
> > wrote:
> > > Android became the primary user of CONFIG_FW_LOADER_USER_HELPER_FALLBACK.
> > >
> > > It would be good for us to hear from Android folks if their current use of
> > > request_firmware_into_buf() is designed in practice to *never* use the 
> > > direct
> > > filesystem firmware loading interface, and always rely instead on the
> > > fallback mechanism.
> > 
> > It's hard to answer this question for Android in general. As far as I
> > can tell the reasons we use CONFIG_FW_LOADER_USER_HELPER(_FALLBACK)
> > are:
> > 1) We have multiple different paths on our devices where firmware can
> > be located, and the direct loader only supports one custom path

FWIW I'd love to consider patches to address this, if this is something
you may find a need for in the future to *avoid* the fallback, however
would like a clean solution.

> > 2) Most of those paths are not mounted by the time the corresponding
> > drivers are loaded, because pretty much all Android kernels today are
> > built without module support, and therefore drivers are loaded well
> > before the firmware partition is mounted

I've given this some more thought and you can address this with initramfs,
this is how other Linux distributions are addressing this. One way to
address this automatically is to scrape the drivers built-in or needed early on
boot in initamfs and if the driver has a MODULE_FIRMWARE() its respective
firmware is added to initramfs as well.

If you *don't* use initramfs, then yes you can obviously run into issues
where your firmware may not be accessible if the driver is somehow loaded
early.

> > 3) I think we use _FALLBACK because doing this with uevents is just
> > the easiest thing to do; our init code has a firmware helper that
> > deals with this and searches the paths that we care about
> > 
> > 2) will change at some point, because Android is moving towards a
> > model where device-specific peripheral drivers will be loaded as
> > modules, and since those modules would likely come from the same
> > partition as the firmware, it's possible that the direct load would
> > succeed (depending on whether the custom path is configured there or
> > not). But I don't think we can rely on the direct loader even in those
> > cases, unless we could configure it with multiple custom paths.

Using initramfs will help, but because of the custom path needs -- you're
right, we don't have anything for that yet, its also a bit unclear if
something nice and clean can be drawn up for it. So perhaps dealing with
the fallback mechanism is the way to go for this for sure, since we already
have support for it.

Just keep in mind that the fallback mechanism costs you about ~13436 bytes.

So, if someone comes up with a clean interface for custom paths I'd love
to consider it to avoid those 13436 bytes.

  Luis

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Luis R. Rodriguez]

On Tue, May 08, 2018 at 03:38:05PM +, Luis R. Rodriguez wrote:
> On Fri, May 04, 2018 at 12:44:37PM -0700, Martijn Coenen wrote:
> > On Wed, Apr 25, 2018 at 10:55 AM, Luis R. Rodriguez  
> > wrote:
> > > Android became the primary user of CONFIG_FW_LOADER_USER_HELPER_FALLBACK.
> > >
> > > It would be good for us to hear from Android folks if their current use of
> > > request_firmware_into_buf() is designed in practice to *never* use the 
> > > direct
> > > filesystem firmware loading interface, and always rely instead on the
> > > fallback mechanism.
> > 
> > It's hard to answer this question for Android in general. As far as I
> > can tell the reasons we use CONFIG_FW_LOADER_USER_HELPER(_FALLBACK)
> > are:
> > 1) We have multiple different paths on our devices where firmware can
> > be located, and the direct loader only supports one custom path

FWIW I'd love to consider patches to address this, if this is something
you may find a need for in the future to *avoid* the fallback, however
would like a clean solution.

> > 2) Most of those paths are not mounted by the time the corresponding
> > drivers are loaded, because pretty much all Android kernels today are
> > built without module support, and therefore drivers are loaded well
> > before the firmware partition is mounted

I've given this some more thought and you can address this with initramfs,
this is how other Linux distributions are addressing this. One way to
address this automatically is to scrape the drivers built-in or needed early on
boot in initamfs and if the driver has a MODULE_FIRMWARE() its respective
firmware is added to initramfs as well.

If you *don't* use initramfs, then yes you can obviously run into issues
where your firmware may not be accessible if the driver is somehow loaded
early.

> > 3) I think we use _FALLBACK because doing this with uevents is just
> > the easiest thing to do; our init code has a firmware helper that
> > deals with this and searches the paths that we care about
> > 
> > 2) will change at some point, because Android is moving towards a
> > model where device-specific peripheral drivers will be loaded as
> > modules, and since those modules would likely come from the same
> > partition as the firmware, it's possible that the direct load would
> > succeed (depending on whether the custom path is configured there or
> > not). But I don't think we can rely on the direct loader even in those
> > cases, unless we could configure it with multiple custom paths.

Using initramfs will help, but because of the custom path needs -- you're
right, we don't have anything for that yet, its also a bit unclear if
something nice and clean can be drawn up for it. So perhaps dealing with
the fallback mechanism is the way to go for this for sure, since we already
have support for it.

Just keep in mind that the fallback mechanism costs you about ~13436 bytes.

So, if someone comes up with a clean interface for custom paths I'd love
to consider it to avoid those 13436 bytes.

  Luis

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Luis R. Rodriguez]

On Fri, May 04, 2018 at 12:44:37PM -0700, Martijn Coenen wrote:
> On Wed, Apr 25, 2018 at 10:55 AM, Luis R. Rodriguez  wrote:
> > Android became the primary user of CONFIG_FW_LOADER_USER_HELPER_FALLBACK.
> >
> > It would be good for us to hear from Android folks if their current use of
> > request_firmware_into_buf() is designed in practice to *never* use the 
> > direct
> > filesystem firmware loading interface, and always rely instead on the
> > fallback mechanism.
> 
> It's hard to answer this question for Android in general. As far as I
> can tell the reasons we use CONFIG_FW_LOADER_USER_HELPER(_FALLBACK)
> are:
> 1) We have multiple different paths on our devices where firmware can
> be located, and the direct loader only supports one custom path
> 2) Most of those paths are not mounted by the time the corresponding
> drivers are loaded, because pretty much all Android kernels today are
> built without module support, and therefore drivers are loaded well
> before the firmware partition is mounted
> 3) I think we use _FALLBACK because doing this with uevents is just
> the easiest thing to do; our init code has a firmware helper that
> deals with this and searches the paths that we care about
> 
> 2) will change at some point, because Android is moving towards a
> model where device-specific peripheral drivers will be loaded as
> modules, and since those modules would likely come from the same
> partition as the firmware, it's possible that the direct load would
> succeed (depending on whether the custom path is configured there or
> not). But I don't think we can rely on the direct loader even in those
> cases, unless we could configure it with multiple custom paths.
> 
> I have no reason to believe request_firmware_into_buf() is special in
> this regard; drivers that depend on it may have their corresponding
> firmware in different locations, so just depending on the direct
> loader would not be good enough.

Thanks! This is very useful! This provides yet-another justification and use
case to document for the fallback mechanism. I'll go and extend it.

> >
> > Is ptr below
> >
> > ret = request_firmware_into_buf(_fw, fw_name, dev,
> > ptr, phdr->p_filesz);
> >
> > Also part of the DMA buffer allocated earlier via:
> >
> > ret = qcom_scm_pas_init_image(pas_id, fw->data, fw->size);
> >
> > Android folks?
> 
> I think the Qualcomm folks owning this (Andy, David, Bjorn, already
> cc'd here) are better suited to answer that question.

Andy, David, Bjorn?

  Luis

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Luis R. Rodriguez]

On Fri, May 04, 2018 at 12:44:37PM -0700, Martijn Coenen wrote:
> On Wed, Apr 25, 2018 at 10:55 AM, Luis R. Rodriguez  wrote:
> > Android became the primary user of CONFIG_FW_LOADER_USER_HELPER_FALLBACK.
> >
> > It would be good for us to hear from Android folks if their current use of
> > request_firmware_into_buf() is designed in practice to *never* use the 
> > direct
> > filesystem firmware loading interface, and always rely instead on the
> > fallback mechanism.
> 
> It's hard to answer this question for Android in general. As far as I
> can tell the reasons we use CONFIG_FW_LOADER_USER_HELPER(_FALLBACK)
> are:
> 1) We have multiple different paths on our devices where firmware can
> be located, and the direct loader only supports one custom path
> 2) Most of those paths are not mounted by the time the corresponding
> drivers are loaded, because pretty much all Android kernels today are
> built without module support, and therefore drivers are loaded well
> before the firmware partition is mounted
> 3) I think we use _FALLBACK because doing this with uevents is just
> the easiest thing to do; our init code has a firmware helper that
> deals with this and searches the paths that we care about
> 
> 2) will change at some point, because Android is moving towards a
> model where device-specific peripheral drivers will be loaded as
> modules, and since those modules would likely come from the same
> partition as the firmware, it's possible that the direct load would
> succeed (depending on whether the custom path is configured there or
> not). But I don't think we can rely on the direct loader even in those
> cases, unless we could configure it with multiple custom paths.
> 
> I have no reason to believe request_firmware_into_buf() is special in
> this regard; drivers that depend on it may have their corresponding
> firmware in different locations, so just depending on the direct
> loader would not be good enough.

Thanks! This is very useful! This provides yet-another justification and use
case to document for the fallback mechanism. I'll go and extend it.

> >
> > Is ptr below
> >
> > ret = request_firmware_into_buf(_fw, fw_name, dev,
> > ptr, phdr->p_filesz);
> >
> > Also part of the DMA buffer allocated earlier via:
> >
> > ret = qcom_scm_pas_init_image(pas_id, fw->data, fw->size);
> >
> > Android folks?
> 
> I think the Qualcomm folks owning this (Andy, David, Bjorn, already
> cc'd here) are better suited to answer that question.

Andy, David, Bjorn?

  Luis

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Martijn Coenen]

On Wed, Apr 25, 2018 at 10:55 AM, Luis R. Rodriguez  wrote:
> Android became the primary user of CONFIG_FW_LOADER_USER_HELPER_FALLBACK.
>
> It would be good for us to hear from Android folks if their current use of
> request_firmware_into_buf() is designed in practice to *never* use the direct
> filesystem firmware loading interface, and always rely instead on the
> fallback mechanism.

It's hard to answer this question for Android in general. As far as I
can tell the reasons we use CONFIG_FW_LOADER_USER_HELPER(_FALLBACK)
are:
1) We have multiple different paths on our devices where firmware can
be located, and the direct loader only supports one custom path
2) Most of those paths are not mounted by the time the corresponding
drivers are loaded, because pretty much all Android kernels today are
built without module support, and therefore drivers are loaded well
before the firmware partition is mounted
3) I think we use _FALLBACK because doing this with uevents is just
the easiest thing to do; our init code has a firmware helper that
deals with this and searches the paths that we care about

2) will change at some point, because Android is moving towards a
model where device-specific peripheral drivers will be loaded as
modules, and since those modules would likely come from the same
partition as the firmware, it's possible that the direct load would
succeed (depending on whether the custom path is configured there or
not). But I don't think we can rely on the direct loader even in those
cases, unless we could configure it with multiple custom paths.

I have no reason to believe request_firmware_into_buf() is special in
this regard; drivers that depend on it may have their corresponding
firmware in different locations, so just depending on the direct
loader would not be good enough.

>
> Is ptr below
>
> ret = request_firmware_into_buf(_fw, fw_name, dev,
> ptr, phdr->p_filesz);
>
> Also part of the DMA buffer allocated earlier via:
>
> ret = qcom_scm_pas_init_image(pas_id, fw->data, fw->size);
>
> Android folks?

I think the Qualcomm folks owning this (Andy, David, Bjorn, already
cc'd here) are better suited to answer that question.

Thanks,
Martijn

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Martijn Coenen]

On Wed, Apr 25, 2018 at 10:55 AM, Luis R. Rodriguez  wrote:
> Android became the primary user of CONFIG_FW_LOADER_USER_HELPER_FALLBACK.
>
> It would be good for us to hear from Android folks if their current use of
> request_firmware_into_buf() is designed in practice to *never* use the direct
> filesystem firmware loading interface, and always rely instead on the
> fallback mechanism.

It's hard to answer this question for Android in general. As far as I
can tell the reasons we use CONFIG_FW_LOADER_USER_HELPER(_FALLBACK)
are:
1) We have multiple different paths on our devices where firmware can
be located, and the direct loader only supports one custom path
2) Most of those paths are not mounted by the time the corresponding
drivers are loaded, because pretty much all Android kernels today are
built without module support, and therefore drivers are loaded well
before the firmware partition is mounted
3) I think we use _FALLBACK because doing this with uevents is just
the easiest thing to do; our init code has a firmware helper that
deals with this and searches the paths that we care about

2) will change at some point, because Android is moving towards a
model where device-specific peripheral drivers will be loaded as
modules, and since those modules would likely come from the same
partition as the firmware, it's possible that the direct load would
succeed (depending on whether the custom path is configured there or
not). But I don't think we can rely on the direct loader even in those
cases, unless we could configure it with multiple custom paths.

I have no reason to believe request_firmware_into_buf() is special in
this regard; drivers that depend on it may have their corresponding
firmware in different locations, so just depending on the direct
loader would not be good enough.

>
> Is ptr below
>
> ret = request_firmware_into_buf(_fw, fw_name, dev,
> ptr, phdr->p_filesz);
>
> Also part of the DMA buffer allocated earlier via:
>
> ret = qcom_scm_pas_init_image(pas_id, fw->data, fw->size);
>
> Android folks?

I think the Qualcomm folks owning this (Andy, David, Bjorn, already
cc'd here) are better suited to answer that question.

Thanks,
Martijn

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Martijn Coenen]

On Thu, May 3, 2018 at 5:21 PM, Luis R. Rodriguez  wrote:
> Android folks, poke below. otherwise we'll have no option but to seriously
> consider Mimi's patch to prevent these calls when IMA appraisal is enforced:

Sorry, figuring out who's the right person to answer this, will get
back to you ASAP.

Martijn

>
> http://lkml.kernel.org/r/1525182503-13849-7-git-send-email-zo...@linux.vnet.ibm.com
>
> Please read below
>
> On Wed, Apr 25, 2018 at 05:55:57PM +, Luis R. Rodriguez wrote:
>> On Wed, Apr 25, 2018 at 01:00:09AM -0400, Mimi Zohar wrote:
>> > On Tue, 2018-04-24 at 23:42 +, Luis R. Rodriguez wrote:
>> > > On Tue, Apr 24, 2018 at 12:07:01PM -0400, Mimi Zohar wrote:
>> > > > On Tue, 2018-04-24 at 17:09 +0200, Hans de Goede wrote:
>> > > If its of any help --
>> > >
>> > > drivers/soc/qcom/mdt_loader.c is the only driver currently using
>> > > request_firmware_into_buf() however I'll note qcom_mdt_load() is used in 
>> > > many
>> > > other drivers so they are wrappers around request_firmware_into_buf():
>> > >
>> > > drivers/gpu/drm/msm/adreno/a5xx_gpu.c:   * adreno_request_fw() handles 
>> > > this, but qcom_mdt_load() does
>> > > drivers/gpu/drm/msm/adreno/a5xx_gpu.c:  ret = qcom_mdt_load(dev, 
>> > > fw, fwname, GPU_PAS_ID,
>> > > drivers/gpu/drm/msm/adreno/a5xx_gpu.c:  ret = qcom_mdt_load(dev, 
>> > > fw, newname, GPU_PAS_ID,
>> > > drivers/media/platform/qcom/venus/firmware.c:   ret = qcom_mdt_load(dev, 
>> > > mdt, fwname, VENUS_PAS_ID, mem_va, mem_phys,
>> > > drivers/remoteproc/qcom_adsp_pil.c: return qcom_mdt_load(adsp->dev, 
>> > > fw, rproc->firmware, adsp->pas_id,
>> > > drivers/remoteproc/qcom_wcnss.c:return qcom_mdt_load(wcnss->dev, 
>> > > fw, rproc->firmware, WCNSS_PAS_ID,
>> > >
>> > > > > As such the current IMA code (from v4.17-rc2) actually does
>> > > > > not handle READING_FIRMWARE_PREALLOC_BUFFER at all,
>> > > >
>> > > > Right, it doesn't yet address READING_FIRMWARE_PREALLOC_BUFFER, but
>> > > > should.
>> > > >
>> > > > Depending on whether the device requesting the firmware has access to
>> > > > the DMA memory, before the signature verification,
>> > >
>> > > It would seem from the original patch review about 
>> > > READING_FIRMWARE_PREALLOC_BUFFER
>> > > that this is not a DMA buffer.
>
> To be very clear I believe Stephen implied this was not DMA buffer. Mimi
> asked for READING_FIRMWARE_DMA if it was:
>
> https://patchwork.kernel.org/patch/9074611/
>
>> > The call sequence:
>> > qcom_mdt_load() -> qcom_scm_pas_init_image() -> dma_alloc_coherent()
>> >
>> > If dma_alloc_coherent() isn't allocating a DMA buffer, then the
>> > function name is misleading/confusing.
>>
>> Hah, by *definition* the device *and* processor has immediate access
>> to data written *immediately* when dma_alloc_coherent() is used. From
>> Documentation/DMA-API.txt:
>>
>> ---
>> Part Ia - Using large DMA-coherent buffers
>> --
>>
>> ::
>>
>> void *
>> dma_alloc_coherent(struct device *dev, size_t size,
>>dma_addr_t *dma_handle, gfp_t flag)
>>
>> Consistent memory is memory for which a write by either the device or
>> the processor can immediately be read by the processor or device
>> without having to worry about caching effects.  (You may however need
>> to make sure to flush the processor's write buffers before telling
>> devices to read that memory.)
>> 
>>
>> Is ptr below
>>
>>   ret = request_firmware_into_buf(_fw, fw_name, dev,
>>   ptr, phdr->p_filesz);
>>
>> Also part of the DMA buffer allocated earlier via:
>>
>> ret = qcom_scm_pas_init_image(pas_id, fw->data, fw->size);
>>
>> Android folks?
>
> Android folks?
>
>> > > The device driver should have access to the buffer pointer with write 
>> > > given
>> > > that with request_firmware_into_buf() the driver is giving full write 
>> > > access to
>> > > the memory pointer so that the firmware API can stuff the firmware it 
>> > > finds
>> > > there.
>> > >
>> > > Firmware signature verification would be up to the device hardware to do 
>> > > upon
>> > > load *after* request_firmware_into_buf().
>> >
>> > We're discussing the kernel's signature verification, not the device
>> > hardware's signature verification.  Can the device driver access the
>> > buffer, before IMA-appraisal has verified the firmware's signature?
>>
>> It will depend on the above question.
>
>   Luis

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Martijn Coenen]

On Thu, May 3, 2018 at 5:21 PM, Luis R. Rodriguez  wrote:
> Android folks, poke below. otherwise we'll have no option but to seriously
> consider Mimi's patch to prevent these calls when IMA appraisal is enforced:

Sorry, figuring out who's the right person to answer this, will get
back to you ASAP.

Martijn

>
> http://lkml.kernel.org/r/1525182503-13849-7-git-send-email-zo...@linux.vnet.ibm.com
>
> Please read below
>
> On Wed, Apr 25, 2018 at 05:55:57PM +, Luis R. Rodriguez wrote:
>> On Wed, Apr 25, 2018 at 01:00:09AM -0400, Mimi Zohar wrote:
>> > On Tue, 2018-04-24 at 23:42 +, Luis R. Rodriguez wrote:
>> > > On Tue, Apr 24, 2018 at 12:07:01PM -0400, Mimi Zohar wrote:
>> > > > On Tue, 2018-04-24 at 17:09 +0200, Hans de Goede wrote:
>> > > If its of any help --
>> > >
>> > > drivers/soc/qcom/mdt_loader.c is the only driver currently using
>> > > request_firmware_into_buf() however I'll note qcom_mdt_load() is used in 
>> > > many
>> > > other drivers so they are wrappers around request_firmware_into_buf():
>> > >
>> > > drivers/gpu/drm/msm/adreno/a5xx_gpu.c:   * adreno_request_fw() handles 
>> > > this, but qcom_mdt_load() does
>> > > drivers/gpu/drm/msm/adreno/a5xx_gpu.c:  ret = qcom_mdt_load(dev, 
>> > > fw, fwname, GPU_PAS_ID,
>> > > drivers/gpu/drm/msm/adreno/a5xx_gpu.c:  ret = qcom_mdt_load(dev, 
>> > > fw, newname, GPU_PAS_ID,
>> > > drivers/media/platform/qcom/venus/firmware.c:   ret = qcom_mdt_load(dev, 
>> > > mdt, fwname, VENUS_PAS_ID, mem_va, mem_phys,
>> > > drivers/remoteproc/qcom_adsp_pil.c: return qcom_mdt_load(adsp->dev, 
>> > > fw, rproc->firmware, adsp->pas_id,
>> > > drivers/remoteproc/qcom_wcnss.c:return qcom_mdt_load(wcnss->dev, 
>> > > fw, rproc->firmware, WCNSS_PAS_ID,
>> > >
>> > > > > As such the current IMA code (from v4.17-rc2) actually does
>> > > > > not handle READING_FIRMWARE_PREALLOC_BUFFER at all,
>> > > >
>> > > > Right, it doesn't yet address READING_FIRMWARE_PREALLOC_BUFFER, but
>> > > > should.
>> > > >
>> > > > Depending on whether the device requesting the firmware has access to
>> > > > the DMA memory, before the signature verification,
>> > >
>> > > It would seem from the original patch review about 
>> > > READING_FIRMWARE_PREALLOC_BUFFER
>> > > that this is not a DMA buffer.
>
> To be very clear I believe Stephen implied this was not DMA buffer. Mimi
> asked for READING_FIRMWARE_DMA if it was:
>
> https://patchwork.kernel.org/patch/9074611/
>
>> > The call sequence:
>> > qcom_mdt_load() -> qcom_scm_pas_init_image() -> dma_alloc_coherent()
>> >
>> > If dma_alloc_coherent() isn't allocating a DMA buffer, then the
>> > function name is misleading/confusing.
>>
>> Hah, by *definition* the device *and* processor has immediate access
>> to data written *immediately* when dma_alloc_coherent() is used. From
>> Documentation/DMA-API.txt:
>>
>> ---
>> Part Ia - Using large DMA-coherent buffers
>> --
>>
>> ::
>>
>> void *
>> dma_alloc_coherent(struct device *dev, size_t size,
>>dma_addr_t *dma_handle, gfp_t flag)
>>
>> Consistent memory is memory for which a write by either the device or
>> the processor can immediately be read by the processor or device
>> without having to worry about caching effects.  (You may however need
>> to make sure to flush the processor's write buffers before telling
>> devices to read that memory.)
>> 
>>
>> Is ptr below
>>
>>   ret = request_firmware_into_buf(_fw, fw_name, dev,
>>   ptr, phdr->p_filesz);
>>
>> Also part of the DMA buffer allocated earlier via:
>>
>> ret = qcom_scm_pas_init_image(pas_id, fw->data, fw->size);
>>
>> Android folks?
>
> Android folks?
>
>> > > The device driver should have access to the buffer pointer with write 
>> > > given
>> > > that with request_firmware_into_buf() the driver is giving full write 
>> > > access to
>> > > the memory pointer so that the firmware API can stuff the firmware it 
>> > > finds
>> > > there.
>> > >
>> > > Firmware signature verification would be up to the device hardware to do 
>> > > upon
>> > > load *after* request_firmware_into_buf().
>> >
>> > We're discussing the kernel's signature verification, not the device
>> > hardware's signature verification.  Can the device driver access the
>> > buffer, before IMA-appraisal has verified the firmware's signature?
>>
>> It will depend on the above question.
>
>   Luis

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Luis R. Rodriguez]

Android folks, poke below. otherwise we'll have no option but to seriously
consider Mimi's patch to prevent these calls when IMA appraisal is enforced:

http://lkml.kernel.org/r/1525182503-13849-7-git-send-email-zo...@linux.vnet.ibm.com

Please read below

On Wed, Apr 25, 2018 at 05:55:57PM +, Luis R. Rodriguez wrote:
> On Wed, Apr 25, 2018 at 01:00:09AM -0400, Mimi Zohar wrote:
> > On Tue, 2018-04-24 at 23:42 +, Luis R. Rodriguez wrote:
> > > On Tue, Apr 24, 2018 at 12:07:01PM -0400, Mimi Zohar wrote:
> > > > On Tue, 2018-04-24 at 17:09 +0200, Hans de Goede wrote:
> > > If its of any help --
> > > 
> > > drivers/soc/qcom/mdt_loader.c is the only driver currently using
> > > request_firmware_into_buf() however I'll note qcom_mdt_load() is used in 
> > > many
> > > other drivers so they are wrappers around request_firmware_into_buf():
> > > 
> > > drivers/gpu/drm/msm/adreno/a5xx_gpu.c:   * adreno_request_fw() handles 
> > > this, but qcom_mdt_load() does
> > > drivers/gpu/drm/msm/adreno/a5xx_gpu.c:  ret = qcom_mdt_load(dev, 
> > > fw, fwname, GPU_PAS_ID,
> > > drivers/gpu/drm/msm/adreno/a5xx_gpu.c:  ret = qcom_mdt_load(dev, 
> > > fw, newname, GPU_PAS_ID,
> > > drivers/media/platform/qcom/venus/firmware.c:   ret = qcom_mdt_load(dev, 
> > > mdt, fwname, VENUS_PAS_ID, mem_va, mem_phys,
> > > drivers/remoteproc/qcom_adsp_pil.c: return qcom_mdt_load(adsp->dev, 
> > > fw, rproc->firmware, adsp->pas_id,
> > > drivers/remoteproc/qcom_wcnss.c:return qcom_mdt_load(wcnss->dev, 
> > > fw, rproc->firmware, WCNSS_PAS_ID,
> > > 
> > > > > As such the current IMA code (from v4.17-rc2) actually does
> > > > > not handle READING_FIRMWARE_PREALLOC_BUFFER at all, 
> > > > 
> > > > Right, it doesn't yet address READING_FIRMWARE_PREALLOC_BUFFER, but
> > > > should.
> > > > 
> > > > Depending on whether the device requesting the firmware has access to
> > > > the DMA memory, before the signature verification, 
> > > 
> > > It would seem from the original patch review about 
> > > READING_FIRMWARE_PREALLOC_BUFFER
> > > that this is not a DMA buffer.

To be very clear I believe Stephen implied this was not DMA buffer. Mimi
asked for READING_FIRMWARE_DMA if it was:

https://patchwork.kernel.org/patch/9074611/

> > The call sequence:
> > qcom_mdt_load() -> qcom_scm_pas_init_image() -> dma_alloc_coherent()
> > 
> > If dma_alloc_coherent() isn't allocating a DMA buffer, then the
> > function name is misleading/confusing.
> 
> Hah, by *definition* the device *and* processor has immediate access
> to data written *immediately* when dma_alloc_coherent() is used. From
> Documentation/DMA-API.txt:
> 
> ---
> Part Ia - Using large DMA-coherent buffers
>   
> --
>   
>   
>   
> ::
>   
>   
>   
> void *
>   
> dma_alloc_coherent(struct device *dev, size_t size,   
>   
>dma_addr_t *dma_handle, gfp_t flag)
>   
>   
>   
> Consistent memory is memory for which a write by either the device or 
>   
> the processor can immediately be read by the processor or device  
>   
> without having to worry about caching effects.  (You may however need 
>   
> to make sure to flush the processor's write buffers before telling
>   
> devices to read that memory.)  
> 
> 
> Is ptr below
> 
>   ret = request_firmware_into_buf(_fw, fw_name, dev,  
>   ptr, phdr->p_filesz); 
> 
> Also part of the DMA buffer allocated earlier via:
> 
> ret = qcom_scm_pas_init_image(pas_id, fw->data, fw->size);
>   
> 
> Android folks?

Android folks?

> > > The device driver should have access to the buffer pointer with write 
> > > given
> > > that with request_firmware_into_buf() the driver is giving full write 
> > > access to
> > > the memory pointer so that the firmware API can stuff the firmware it 
> > > finds
> > > there.
> > > 
> > > Firmware signature verification would be up to the device hardware to do 
> > > upon
> > > load *after* request_firmware_into_buf().
> > 
> > We're discussing the kernel's signature verification, not the device
> > hardware's signature verification.  Can the device driver access the
> > buffer, before IMA-appraisal has verified the firmware's signature?
> 
> It will depend on the above question.

  Luis

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Luis R. Rodriguez]

Android folks, poke below. otherwise we'll have no option but to seriously
consider Mimi's patch to prevent these calls when IMA appraisal is enforced:

http://lkml.kernel.org/r/1525182503-13849-7-git-send-email-zo...@linux.vnet.ibm.com

Please read below

On Wed, Apr 25, 2018 at 05:55:57PM +, Luis R. Rodriguez wrote:
> On Wed, Apr 25, 2018 at 01:00:09AM -0400, Mimi Zohar wrote:
> > On Tue, 2018-04-24 at 23:42 +, Luis R. Rodriguez wrote:
> > > On Tue, Apr 24, 2018 at 12:07:01PM -0400, Mimi Zohar wrote:
> > > > On Tue, 2018-04-24 at 17:09 +0200, Hans de Goede wrote:
> > > If its of any help --
> > > 
> > > drivers/soc/qcom/mdt_loader.c is the only driver currently using
> > > request_firmware_into_buf() however I'll note qcom_mdt_load() is used in 
> > > many
> > > other drivers so they are wrappers around request_firmware_into_buf():
> > > 
> > > drivers/gpu/drm/msm/adreno/a5xx_gpu.c:   * adreno_request_fw() handles 
> > > this, but qcom_mdt_load() does
> > > drivers/gpu/drm/msm/adreno/a5xx_gpu.c:  ret = qcom_mdt_load(dev, 
> > > fw, fwname, GPU_PAS_ID,
> > > drivers/gpu/drm/msm/adreno/a5xx_gpu.c:  ret = qcom_mdt_load(dev, 
> > > fw, newname, GPU_PAS_ID,
> > > drivers/media/platform/qcom/venus/firmware.c:   ret = qcom_mdt_load(dev, 
> > > mdt, fwname, VENUS_PAS_ID, mem_va, mem_phys,
> > > drivers/remoteproc/qcom_adsp_pil.c: return qcom_mdt_load(adsp->dev, 
> > > fw, rproc->firmware, adsp->pas_id,
> > > drivers/remoteproc/qcom_wcnss.c:return qcom_mdt_load(wcnss->dev, 
> > > fw, rproc->firmware, WCNSS_PAS_ID,
> > > 
> > > > > As such the current IMA code (from v4.17-rc2) actually does
> > > > > not handle READING_FIRMWARE_PREALLOC_BUFFER at all, 
> > > > 
> > > > Right, it doesn't yet address READING_FIRMWARE_PREALLOC_BUFFER, but
> > > > should.
> > > > 
> > > > Depending on whether the device requesting the firmware has access to
> > > > the DMA memory, before the signature verification, 
> > > 
> > > It would seem from the original patch review about 
> > > READING_FIRMWARE_PREALLOC_BUFFER
> > > that this is not a DMA buffer.

To be very clear I believe Stephen implied this was not DMA buffer. Mimi
asked for READING_FIRMWARE_DMA if it was:

https://patchwork.kernel.org/patch/9074611/

> > The call sequence:
> > qcom_mdt_load() -> qcom_scm_pas_init_image() -> dma_alloc_coherent()
> > 
> > If dma_alloc_coherent() isn't allocating a DMA buffer, then the
> > function name is misleading/confusing.
> 
> Hah, by *definition* the device *and* processor has immediate access
> to data written *immediately* when dma_alloc_coherent() is used. From
> Documentation/DMA-API.txt:
> 
> ---
> Part Ia - Using large DMA-coherent buffers
>   
> --
>   
>   
>   
> ::
>   
>   
>   
> void *
>   
> dma_alloc_coherent(struct device *dev, size_t size,   
>   
>dma_addr_t *dma_handle, gfp_t flag)
>   
>   
>   
> Consistent memory is memory for which a write by either the device or 
>   
> the processor can immediately be read by the processor or device  
>   
> without having to worry about caching effects.  (You may however need 
>   
> to make sure to flush the processor's write buffers before telling
>   
> devices to read that memory.)  
> 
> 
> Is ptr below
> 
>   ret = request_firmware_into_buf(_fw, fw_name, dev,  
>   ptr, phdr->p_filesz); 
> 
> Also part of the DMA buffer allocated earlier via:
> 
> ret = qcom_scm_pas_init_image(pas_id, fw->data, fw->size);
>   
> 
> Android folks?

Android folks?

> > > The device driver should have access to the buffer pointer with write 
> > > given
> > > that with request_firmware_into_buf() the driver is giving full write 
> > > access to
> > > the memory pointer so that the firmware API can stuff the firmware it 
> > > finds
> > > there.
> > > 
> > > Firmware signature verification would be up to the device hardware to do 
> > > upon
> > > load *after* request_firmware_into_buf().
> > 
> > We're discussing the kernel's signature verification, not the device
> > hardware's signature verification.  Can the device driver access the
> > buffer, before IMA-appraisal has verified the firmware's signature?
> 
> It will depend on the above question.

  Luis

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Luis R. Rodriguez]

On Wed, Apr 25, 2018 at 01:00:09AM -0400, Mimi Zohar wrote:
> On Tue, 2018-04-24 at 23:42 +, Luis R. Rodriguez wrote:
> > On Tue, Apr 24, 2018 at 12:07:01PM -0400, Mimi Zohar wrote:
> > > On Tue, 2018-04-24 at 17:09 +0200, Hans de Goede wrote:
> > > > On 23-04-18 23:11, Luis R. Rodriguez wrote:
> > > > > Hans, please see use of READING_FIRMWARE_PREALLOC_BUFFER, we'll need 
> > > > > a new ID
> > > > > and security for this type of request so IMA can reject it if the 
> > > > > policy is
> > > > > configured for it.
> > > > 
> > > > Hmm, interesting, actually it seems like the whole existence
> > > > of READING_FIRMWARE_PREALLOC_BUFFER is a mistake, 
> > 
> > request_firmware_into_buf() was merged without my own review, however,
> > the ID thing did get review from Mimi:
> > 
> > https://patchwork.kernel.org/patch/9074611/
> > 
> > The ID is not for IMA alone, its for any LSM to decide what to do.
> > Note Mimi asked for READING_FIRMWARE_DMA if such buffer was in DMA,
> > otherise READING_FIRMWARE_PREALLOC_BUFFER was suggested.
> > 
> > Mimi why did you want a separate ID for it back before?
> 
> The point of commit a098ecd2fa7d ("firmware: support loading into a
> pre-allocated buffer") is to avoid reading the firmware into kernel
> memory and then copying it "to it's final resting place".  My concern
> is that if the device driver has access to the buffer, it could access
> the buffer prior to the firmware's signature having been verified by
> the kernel.

If request_firmware_into_buf() is used and the firmware was found in
/lib/firmware/ paths then the driver will *not* use the firmware prior
to any LSM doing any firmware signature verification because
kernel_read_file_from_path() and in turn security_kernel_read_file().

The firmware API has a fallback mechanism [0] though, and if that is used then
security_kernel_post_read_file() is used once the firmware is loaded through
the sysfs interface *prior* to handing the firmware data to the driver. As
Hans noted though security_kernel_post_read_file() currently *only* uses
READING_FIRMWARE, so this needs to be fixed. Also note though that LSMs
get a hint of what is going to happen *soon* prior to the fallback
mechanism kicking on as we travere the /lib/firmware/ paths for direct
filesystem loading.

If this is not sufficient to cover LSM appraisals *one* option could be to
have security_kernel_read_file() return a special error of some sort
for READING_FIRMWARE_PREALLOC_BUFFER so that kernel_read_file_from_path()
users could *know* to fatally give up.

Currently the device drivers using request_firmware_into_buf() can end up
getting the buffer with firmware stashed in it without having the kernel do any
firmware signature verification at all through its LSMs. The LSM hooks added to
the firmware loader long ago by Kees via commit 6593d9245bc66 ("firmware_class:
perform new LSM checks") on v3.17 added an LSM for direct filesystem lookups,
but on the fallback mechanism seems to have only added a post LSM hook
security_kernel_fw_from_file().

There is also a custom fallback mechanism [1] which can be used if the path to
the firmware may be out of the /lib/firmware/ paths or perhaps the firmware
requires some very custom fetching of some sort. The only thing this does
though is just *not* issue a uevent when we don't find the firmware and also
sets the timeout to a practically never-ending value. The custom fallback
mechanism is only usable for request_firmware_nowait() though. In retrospect
the custom fallback mechanism is pure crap and these days we've acknowledged
that even in crazy custom firmware fetching cases folks should be able to
accomplish this by relying on uevents and using the firmwared [2] or forking
it, or a different similar proprietary similar solution, which would just
monitor for uevents for firmware and just Do The Right Thing (TM).

Consider some mobile devices which may want to fetch it from some custom
partition which only it can know how to get.

There is a kernel config option which enables the fallback mechanism always,
This is now easily readable as follows:

drivers/base/firmware_loader/fallback_table.c

struct firmware_fallback_config fw_fallback_config = {
.force_sysfs_fallback = 
IS_ENABLED(CONFIG_FW_LOADER_USER_HELPER_FALLBACK),
.loading_timeout = 60,
.old_timeout = 60,
};

Even if this is used we always do direct fs lookups first.

Android became the primary user of CONFIG_FW_LOADER_USER_HELPER_FALLBACK.

It would be good for us to hear from Android folks if their current use of
request_firmware_into_buf() is designed in practice to *never* use the direct
filesystem firmware loading interface, and always rely instead on the
fallback mechanism.

That would answer help your appraisal question in practice today.

[0] 
https://www.kernel.org/doc/html/latest/driver-api/firmware/fallback-mechanisms.html
[1] 

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Luis R. Rodriguez]

On Wed, Apr 25, 2018 at 01:00:09AM -0400, Mimi Zohar wrote:
> On Tue, 2018-04-24 at 23:42 +, Luis R. Rodriguez wrote:
> > On Tue, Apr 24, 2018 at 12:07:01PM -0400, Mimi Zohar wrote:
> > > On Tue, 2018-04-24 at 17:09 +0200, Hans de Goede wrote:
> > > > On 23-04-18 23:11, Luis R. Rodriguez wrote:
> > > > > Hans, please see use of READING_FIRMWARE_PREALLOC_BUFFER, we'll need 
> > > > > a new ID
> > > > > and security for this type of request so IMA can reject it if the 
> > > > > policy is
> > > > > configured for it.
> > > > 
> > > > Hmm, interesting, actually it seems like the whole existence
> > > > of READING_FIRMWARE_PREALLOC_BUFFER is a mistake, 
> > 
> > request_firmware_into_buf() was merged without my own review, however,
> > the ID thing did get review from Mimi:
> > 
> > https://patchwork.kernel.org/patch/9074611/
> > 
> > The ID is not for IMA alone, its for any LSM to decide what to do.
> > Note Mimi asked for READING_FIRMWARE_DMA if such buffer was in DMA,
> > otherise READING_FIRMWARE_PREALLOC_BUFFER was suggested.
> > 
> > Mimi why did you want a separate ID for it back before?
> 
> The point of commit a098ecd2fa7d ("firmware: support loading into a
> pre-allocated buffer") is to avoid reading the firmware into kernel
> memory and then copying it "to it's final resting place".  My concern
> is that if the device driver has access to the buffer, it could access
> the buffer prior to the firmware's signature having been verified by
> the kernel.

If request_firmware_into_buf() is used and the firmware was found in
/lib/firmware/ paths then the driver will *not* use the firmware prior
to any LSM doing any firmware signature verification because
kernel_read_file_from_path() and in turn security_kernel_read_file().

The firmware API has a fallback mechanism [0] though, and if that is used then
security_kernel_post_read_file() is used once the firmware is loaded through
the sysfs interface *prior* to handing the firmware data to the driver. As
Hans noted though security_kernel_post_read_file() currently *only* uses
READING_FIRMWARE, so this needs to be fixed. Also note though that LSMs
get a hint of what is going to happen *soon* prior to the fallback
mechanism kicking on as we travere the /lib/firmware/ paths for direct
filesystem loading.

If this is not sufficient to cover LSM appraisals *one* option could be to
have security_kernel_read_file() return a special error of some sort
for READING_FIRMWARE_PREALLOC_BUFFER so that kernel_read_file_from_path()
users could *know* to fatally give up.

Currently the device drivers using request_firmware_into_buf() can end up
getting the buffer with firmware stashed in it without having the kernel do any
firmware signature verification at all through its LSMs. The LSM hooks added to
the firmware loader long ago by Kees via commit 6593d9245bc66 ("firmware_class:
perform new LSM checks") on v3.17 added an LSM for direct filesystem lookups,
but on the fallback mechanism seems to have only added a post LSM hook
security_kernel_fw_from_file().

There is also a custom fallback mechanism [1] which can be used if the path to
the firmware may be out of the /lib/firmware/ paths or perhaps the firmware
requires some very custom fetching of some sort. The only thing this does
though is just *not* issue a uevent when we don't find the firmware and also
sets the timeout to a practically never-ending value. The custom fallback
mechanism is only usable for request_firmware_nowait() though. In retrospect
the custom fallback mechanism is pure crap and these days we've acknowledged
that even in crazy custom firmware fetching cases folks should be able to
accomplish this by relying on uevents and using the firmwared [2] or forking
it, or a different similar proprietary similar solution, which would just
monitor for uevents for firmware and just Do The Right Thing (TM).

Consider some mobile devices which may want to fetch it from some custom
partition which only it can know how to get.

There is a kernel config option which enables the fallback mechanism always,
This is now easily readable as follows:

drivers/base/firmware_loader/fallback_table.c

struct firmware_fallback_config fw_fallback_config = {
.force_sysfs_fallback = 
IS_ENABLED(CONFIG_FW_LOADER_USER_HELPER_FALLBACK),
.loading_timeout = 60,
.old_timeout = 60,
};

Even if this is used we always do direct fs lookups first.

Android became the primary user of CONFIG_FW_LOADER_USER_HELPER_FALLBACK.

It would be good for us to hear from Android folks if their current use of
request_firmware_into_buf() is designed in practice to *never* use the direct
filesystem firmware loading interface, and always rely instead on the
fallback mechanism.

That would answer help your appraisal question in practice today.

[0] 
https://www.kernel.org/doc/html/latest/driver-api/firmware/fallback-mechanisms.html
[1] 

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Mimi Zohar]

On Tue, 2018-04-24 at 23:42 +, Luis R. Rodriguez wrote:
> On Tue, Apr 24, 2018 at 12:07:01PM -0400, Mimi Zohar wrote:
> > On Tue, 2018-04-24 at 17:09 +0200, Hans de Goede wrote:
> > > Hi,
> > > 
> > > On 23-04-18 23:11, Luis R. Rodriguez wrote:
> > > > Hans, please see use of READING_FIRMWARE_PREALLOC_BUFFER, we'll need a 
> > > > new ID
> > > > and security for this type of request so IMA can reject it if the 
> > > > policy is
> > > > configured for it.
> > > 
> > > Hmm, interesting, actually it seems like the whole existence
> > > of READING_FIRMWARE_PREALLOC_BUFFER is a mistake, 
> 
> request_firmware_into_buf() was merged without my own review, however,
> the ID thing did get review from Mimi:
> 
> https://patchwork.kernel.org/patch/9074611/
> 
> The ID is not for IMA alone, its for any LSM to decide what to do.
> Note Mimi asked for READING_FIRMWARE_DMA if such buffer was in DMA,
> otherise READING_FIRMWARE_PREALLOC_BUFFER was suggested.
> 
> > > the IMA
> > > framework really does not care if we are loading the firmware
> > > into memory allocated by the firmware-loader code, or into
> > > memory allocated by the device-driver requesting the firmware.
> 
> That's up to LSM folks to decide. We have these so far:
> 
> #define __kernel_read_file_id(id) \   
>   
> id(UNKNOWN, unknown)\ 
>   
> id(FIRMWARE, firmware)  \ 
>   
> id(FIRMWARE_PREALLOC_BUFFER, firmware)  \ 
>   
> id(MODULE, kernel-module)   \ 
>   
> id(KEXEC_IMAGE, kexec-image)\ 
>   
> id(KEXEC_INITRAMFS, kexec-initramfs)\ 
>   
> id(POLICY, security-policy) \ 
>   
> id(X509_CERTIFICATE, x509-certificate)  \ 
>   
> id(MAX_ID, )  
> 
> The first type of IDs added was about type of files the kernel
> LSMs may want to do different things for.
> 
> Mimi why did you want a separate ID for it back before?

The point of commit a098ecd2fa7d ("firmware: support loading into a
pre-allocated buffer") is to avoid reading the firmware into kernel
memory and then copying it "to it's final resting place".  My concern
is that if the device driver has access to the buffer, it could access
the buffer prior to the firmware's signature having been verified by
the kernel.

In tightly controlled environments interested in limiting which signed
firmware version is loaded, require's the device driver not having
access to the buffer until after the signature has been verified by
the kernel (eg. IMA-appraisal).

> 
> I should note now that request_firmware_into_buf() and its
> READING_FIRMWARE_PREALLOC_BUFFER was to enable a driver on memory constrained
> devices. The files are large (commit says 16 MiB).
> 
> I've heard of larger possible files with remoteproc and with Android using
> the custom fallback mechanism -- which could mean a proprietary tool
> fetching firmware from a random special place on a device.
> 
> I could perhaps imagine an LSM which may be aware of such type of
> arrangement may want to do its own vetting of some sort, but this
> would not be specific to READING_FIRMWARE_PREALLOC_BUFFER, but rather
> the custom fallback mechaism.
> 
> Whether or not the buffer was preallocated by the driver seems a little
> odd for security folks to do something different with it. Security LSM
> folks please chime in.
> 
> I could see a bit more of a use case for an ID for firmware scraped
> from EFI, which Hans' patch will provide. But that *also* should get
> good review from other LSM folks.
> 
> One of the issues with accepting more IDs loosely is where do we
> stop though? If no one really is using READING_FIRMWARE_PREALLOC_BUFFER
> I'd say lets remove it. Likewise, for this EFI thing I'd like an idea
> if we really are going to have users for it.
> 
> If its of any help --
> 
> drivers/soc/qcom/mdt_loader.c is the only driver currently using
> request_firmware_into_buf() however I'll note qcom_mdt_load() is used in many
> other drivers so they are wrappers around request_firmware_into_buf():
> 
> drivers/gpu/drm/msm/adreno/a5xx_gpu.c:   * adreno_request_fw() handles this, 
> but qcom_mdt_load() does
> drivers/gpu/drm/msm/adreno/a5xx_gpu.c:  ret = qcom_mdt_load(dev, fw, 
> fwname, GPU_PAS_ID,
> drivers/gpu/drm/msm/adreno/a5xx_gpu.c:  ret = qcom_mdt_load(dev, fw, 
> newname, GPU_PAS_ID,
> drivers/media/platform/qcom/venus/firmware.c:   ret = qcom_mdt_load(dev, mdt, 
> fwname, VENUS_PAS_ID, mem_va, mem_phys,
> drivers/remoteproc/qcom_adsp_pil.c: return qcom_mdt_load(adsp->dev, fw, 
> rproc->firmware, adsp->pas_id,
> drivers/remoteproc/qcom_wcnss.c:return qcom_mdt_load(wcnss->dev, fw, 
> rproc->firmware, WCNSS_PAS_ID,

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Mimi Zohar]

On Tue, 2018-04-24 at 23:42 +, Luis R. Rodriguez wrote:
> On Tue, Apr 24, 2018 at 12:07:01PM -0400, Mimi Zohar wrote:
> > On Tue, 2018-04-24 at 17:09 +0200, Hans de Goede wrote:
> > > Hi,
> > > 
> > > On 23-04-18 23:11, Luis R. Rodriguez wrote:
> > > > Hans, please see use of READING_FIRMWARE_PREALLOC_BUFFER, we'll need a 
> > > > new ID
> > > > and security for this type of request so IMA can reject it if the 
> > > > policy is
> > > > configured for it.
> > > 
> > > Hmm, interesting, actually it seems like the whole existence
> > > of READING_FIRMWARE_PREALLOC_BUFFER is a mistake, 
> 
> request_firmware_into_buf() was merged without my own review, however,
> the ID thing did get review from Mimi:
> 
> https://patchwork.kernel.org/patch/9074611/
> 
> The ID is not for IMA alone, its for any LSM to decide what to do.
> Note Mimi asked for READING_FIRMWARE_DMA if such buffer was in DMA,
> otherise READING_FIRMWARE_PREALLOC_BUFFER was suggested.
> 
> > > the IMA
> > > framework really does not care if we are loading the firmware
> > > into memory allocated by the firmware-loader code, or into
> > > memory allocated by the device-driver requesting the firmware.
> 
> That's up to LSM folks to decide. We have these so far:
> 
> #define __kernel_read_file_id(id) \   
>   
> id(UNKNOWN, unknown)\ 
>   
> id(FIRMWARE, firmware)  \ 
>   
> id(FIRMWARE_PREALLOC_BUFFER, firmware)  \ 
>   
> id(MODULE, kernel-module)   \ 
>   
> id(KEXEC_IMAGE, kexec-image)\ 
>   
> id(KEXEC_INITRAMFS, kexec-initramfs)\ 
>   
> id(POLICY, security-policy) \ 
>   
> id(X509_CERTIFICATE, x509-certificate)  \ 
>   
> id(MAX_ID, )  
> 
> The first type of IDs added was about type of files the kernel
> LSMs may want to do different things for.
> 
> Mimi why did you want a separate ID for it back before?

The point of commit a098ecd2fa7d ("firmware: support loading into a
pre-allocated buffer") is to avoid reading the firmware into kernel
memory and then copying it "to it's final resting place".  My concern
is that if the device driver has access to the buffer, it could access
the buffer prior to the firmware's signature having been verified by
the kernel.

In tightly controlled environments interested in limiting which signed
firmware version is loaded, require's the device driver not having
access to the buffer until after the signature has been verified by
the kernel (eg. IMA-appraisal).

> 
> I should note now that request_firmware_into_buf() and its
> READING_FIRMWARE_PREALLOC_BUFFER was to enable a driver on memory constrained
> devices. The files are large (commit says 16 MiB).
> 
> I've heard of larger possible files with remoteproc and with Android using
> the custom fallback mechanism -- which could mean a proprietary tool
> fetching firmware from a random special place on a device.
> 
> I could perhaps imagine an LSM which may be aware of such type of
> arrangement may want to do its own vetting of some sort, but this
> would not be specific to READING_FIRMWARE_PREALLOC_BUFFER, but rather
> the custom fallback mechaism.
> 
> Whether or not the buffer was preallocated by the driver seems a little
> odd for security folks to do something different with it. Security LSM
> folks please chime in.
> 
> I could see a bit more of a use case for an ID for firmware scraped
> from EFI, which Hans' patch will provide. But that *also* should get
> good review from other LSM folks.
> 
> One of the issues with accepting more IDs loosely is where do we
> stop though? If no one really is using READING_FIRMWARE_PREALLOC_BUFFER
> I'd say lets remove it. Likewise, for this EFI thing I'd like an idea
> if we really are going to have users for it.
> 
> If its of any help --
> 
> drivers/soc/qcom/mdt_loader.c is the only driver currently using
> request_firmware_into_buf() however I'll note qcom_mdt_load() is used in many
> other drivers so they are wrappers around request_firmware_into_buf():
> 
> drivers/gpu/drm/msm/adreno/a5xx_gpu.c:   * adreno_request_fw() handles this, 
> but qcom_mdt_load() does
> drivers/gpu/drm/msm/adreno/a5xx_gpu.c:  ret = qcom_mdt_load(dev, fw, 
> fwname, GPU_PAS_ID,
> drivers/gpu/drm/msm/adreno/a5xx_gpu.c:  ret = qcom_mdt_load(dev, fw, 
> newname, GPU_PAS_ID,
> drivers/media/platform/qcom/venus/firmware.c:   ret = qcom_mdt_load(dev, mdt, 
> fwname, VENUS_PAS_ID, mem_va, mem_phys,
> drivers/remoteproc/qcom_adsp_pil.c: return qcom_mdt_load(adsp->dev, fw, 
> rproc->firmware, adsp->pas_id,
> drivers/remoteproc/qcom_wcnss.c:return qcom_mdt_load(wcnss->dev, fw, 
> rproc->firmware, WCNSS_PAS_ID,

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Luis R. Rodriguez]

On Tue, Apr 24, 2018 at 12:07:01PM -0400, Mimi Zohar wrote:
> On Tue, 2018-04-24 at 17:09 +0200, Hans de Goede wrote:
> > Hi,
> > 
> > On 23-04-18 23:11, Luis R. Rodriguez wrote:
> > > Hans, please see use of READING_FIRMWARE_PREALLOC_BUFFER, we'll need a 
> > > new ID
> > > and security for this type of request so IMA can reject it if the policy 
> > > is
> > > configured for it.
> > 
> > Hmm, interesting, actually it seems like the whole existence
> > of READING_FIRMWARE_PREALLOC_BUFFER is a mistake, 

request_firmware_into_buf() was merged without my own review, however,
the ID thing did get review from Mimi:

https://patchwork.kernel.org/patch/9074611/

The ID is not for IMA alone, its for any LSM to decide what to do.
Note Mimi asked for READING_FIRMWARE_DMA if such buffer was in DMA,
otherise READING_FIRMWARE_PREALLOC_BUFFER was suggested.

> > the IMA
> > framework really does not care if we are loading the firmware
> > into memory allocated by the firmware-loader code, or into
> > memory allocated by the device-driver requesting the firmware.

That's up to LSM folks to decide. We have these so far:

#define __kernel_read_file_id(id) \ 
id(UNKNOWN, unknown)\   
id(FIRMWARE, firmware)  \   
id(FIRMWARE_PREALLOC_BUFFER, firmware)  \   
id(MODULE, kernel-module)   \   
id(KEXEC_IMAGE, kexec-image)\   
id(KEXEC_INITRAMFS, kexec-initramfs)\   
id(POLICY, security-policy) \   
id(X509_CERTIFICATE, x509-certificate)  \   
id(MAX_ID, )  

The first type of IDs added was about type of files the kernel
LSMs may want to do different things for.

Mimi why did you want a separate ID for it back before?

I should note now that request_firmware_into_buf() and its
READING_FIRMWARE_PREALLOC_BUFFER was to enable a driver on memory constrained
devices. The files are large (commit says 16 MiB).

I've heard of larger possible files with remoteproc and with Android using
the custom fallback mechanism -- which could mean a proprietary tool
fetching firmware from a random special place on a device.

I could perhaps imagine an LSM which may be aware of such type of
arrangement may want to do its own vetting of some sort, but this
would not be specific to READING_FIRMWARE_PREALLOC_BUFFER, but rather
the custom fallback mechaism.

Whether or not the buffer was preallocated by the driver seems a little
odd for security folks to do something different with it. Security LSM
folks please chime in.

I could see a bit more of a use case for an ID for firmware scraped
from EFI, which Hans' patch will provide. But that *also* should get
good review from other LSM folks.

One of the issues with accepting more IDs loosely is where do we
stop though? If no one really is using READING_FIRMWARE_PREALLOC_BUFFER
I'd say lets remove it. Likewise, for this EFI thing I'd like an idea
if we really are going to have users for it.

If its of any help --

drivers/soc/qcom/mdt_loader.c is the only driver currently using
request_firmware_into_buf() however I'll note qcom_mdt_load() is used in many
other drivers so they are wrappers around request_firmware_into_buf():

drivers/gpu/drm/msm/adreno/a5xx_gpu.c:   * adreno_request_fw() handles this, 
but qcom_mdt_load() does
drivers/gpu/drm/msm/adreno/a5xx_gpu.c:  ret = qcom_mdt_load(dev, fw, 
fwname, GPU_PAS_ID,
drivers/gpu/drm/msm/adreno/a5xx_gpu.c:  ret = qcom_mdt_load(dev, fw, 
newname, GPU_PAS_ID,
drivers/media/platform/qcom/venus/firmware.c:   ret = qcom_mdt_load(dev, mdt, 
fwname, VENUS_PAS_ID, mem_va, mem_phys,
drivers/remoteproc/qcom_adsp_pil.c: return qcom_mdt_load(adsp->dev, fw, 
rproc->firmware, adsp->pas_id,
drivers/remoteproc/qcom_wcnss.c:return qcom_mdt_load(wcnss->dev, fw, 
rproc->firmware, WCNSS_PAS_ID,

Are we going to add more IDs for more types of firmware?
What type of *different* decisions could LSMs take if the firmware
was being written to a buffer? Or in this new case that is coming
up, if the file came scraping EFI, would having that information
be useful?

> > As such the current IMA code (from v4.17-rc2) actually does
> > not handle READING_FIRMWARE_PREALLOC_BUFFER at all, 
> 
> Right, it doesn't yet address READING_FIRMWARE_PREALLOC_BUFFER, but
> should.
> 
> Depending on whether the device requesting the firmware has access to
> the DMA memory, before the signature verification, 

It would seem from the original patch review about 
READING_FIRMWARE_PREALLOC_BUFFER
that this is not a DMA buffer.

The device driver should have access to the buffer pointer with write given
that with request_firmware_into_buf() the driver is giving full write 

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Luis R. Rodriguez]

On Tue, Apr 24, 2018 at 12:07:01PM -0400, Mimi Zohar wrote:
> On Tue, 2018-04-24 at 17:09 +0200, Hans de Goede wrote:
> > Hi,
> > 
> > On 23-04-18 23:11, Luis R. Rodriguez wrote:
> > > Hans, please see use of READING_FIRMWARE_PREALLOC_BUFFER, we'll need a 
> > > new ID
> > > and security for this type of request so IMA can reject it if the policy 
> > > is
> > > configured for it.
> > 
> > Hmm, interesting, actually it seems like the whole existence
> > of READING_FIRMWARE_PREALLOC_BUFFER is a mistake, 

request_firmware_into_buf() was merged without my own review, however,
the ID thing did get review from Mimi:

https://patchwork.kernel.org/patch/9074611/

The ID is not for IMA alone, its for any LSM to decide what to do.
Note Mimi asked for READING_FIRMWARE_DMA if such buffer was in DMA,
otherise READING_FIRMWARE_PREALLOC_BUFFER was suggested.

> > the IMA
> > framework really does not care if we are loading the firmware
> > into memory allocated by the firmware-loader code, or into
> > memory allocated by the device-driver requesting the firmware.

That's up to LSM folks to decide. We have these so far:

#define __kernel_read_file_id(id) \ 
id(UNKNOWN, unknown)\   
id(FIRMWARE, firmware)  \   
id(FIRMWARE_PREALLOC_BUFFER, firmware)  \   
id(MODULE, kernel-module)   \   
id(KEXEC_IMAGE, kexec-image)\   
id(KEXEC_INITRAMFS, kexec-initramfs)\   
id(POLICY, security-policy) \   
id(X509_CERTIFICATE, x509-certificate)  \   
id(MAX_ID, )  

The first type of IDs added was about type of files the kernel
LSMs may want to do different things for.

Mimi why did you want a separate ID for it back before?

I should note now that request_firmware_into_buf() and its
READING_FIRMWARE_PREALLOC_BUFFER was to enable a driver on memory constrained
devices. The files are large (commit says 16 MiB).

I've heard of larger possible files with remoteproc and with Android using
the custom fallback mechanism -- which could mean a proprietary tool
fetching firmware from a random special place on a device.

I could perhaps imagine an LSM which may be aware of such type of
arrangement may want to do its own vetting of some sort, but this
would not be specific to READING_FIRMWARE_PREALLOC_BUFFER, but rather
the custom fallback mechaism.

Whether or not the buffer was preallocated by the driver seems a little
odd for security folks to do something different with it. Security LSM
folks please chime in.

I could see a bit more of a use case for an ID for firmware scraped
from EFI, which Hans' patch will provide. But that *also* should get
good review from other LSM folks.

One of the issues with accepting more IDs loosely is where do we
stop though? If no one really is using READING_FIRMWARE_PREALLOC_BUFFER
I'd say lets remove it. Likewise, for this EFI thing I'd like an idea
if we really are going to have users for it.

If its of any help --

drivers/soc/qcom/mdt_loader.c is the only driver currently using
request_firmware_into_buf() however I'll note qcom_mdt_load() is used in many
other drivers so they are wrappers around request_firmware_into_buf():

drivers/gpu/drm/msm/adreno/a5xx_gpu.c:   * adreno_request_fw() handles this, 
but qcom_mdt_load() does
drivers/gpu/drm/msm/adreno/a5xx_gpu.c:  ret = qcom_mdt_load(dev, fw, 
fwname, GPU_PAS_ID,
drivers/gpu/drm/msm/adreno/a5xx_gpu.c:  ret = qcom_mdt_load(dev, fw, 
newname, GPU_PAS_ID,
drivers/media/platform/qcom/venus/firmware.c:   ret = qcom_mdt_load(dev, mdt, 
fwname, VENUS_PAS_ID, mem_va, mem_phys,
drivers/remoteproc/qcom_adsp_pil.c: return qcom_mdt_load(adsp->dev, fw, 
rproc->firmware, adsp->pas_id,
drivers/remoteproc/qcom_wcnss.c:return qcom_mdt_load(wcnss->dev, fw, 
rproc->firmware, WCNSS_PAS_ID,

Are we going to add more IDs for more types of firmware?
What type of *different* decisions could LSMs take if the firmware
was being written to a buffer? Or in this new case that is coming
up, if the file came scraping EFI, would having that information
be useful?

> > As such the current IMA code (from v4.17-rc2) actually does
> > not handle READING_FIRMWARE_PREALLOC_BUFFER at all, 
> 
> Right, it doesn't yet address READING_FIRMWARE_PREALLOC_BUFFER, but
> should.
> 
> Depending on whether the device requesting the firmware has access to
> the DMA memory, before the signature verification, 

It would seem from the original patch review about 
READING_FIRMWARE_PREALLOC_BUFFER
that this is not a DMA buffer.

The device driver should have access to the buffer pointer with write given
that with request_firmware_into_buf() the driver is giving full write 

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Hans de Goede]

Hi,

On 24-04-18 18:07, Mimi Zohar wrote:

On Tue, 2018-04-24 at 17:09 +0200, Hans de Goede wrote:

Hi,

On 23-04-18 23:11, Luis R. Rodriguez wrote:

Hans, please see use of READING_FIRMWARE_PREALLOC_BUFFER, we'll need a new ID
and security for this type of request so IMA can reject it if the policy is
configured for it.


Hmm, interesting, actually it seems like the whole existence
of READING_FIRMWARE_PREALLOC_BUFFER is a mistake, the IMA
framework really does not care if we are loading the firmware
into memory allocated by the firmware-loader code, or into
memory allocated by the device-driver requesting the firmware.

As such the current IMA code (from v4.17-rc2) actually does
not handle READING_FIRMWARE_PREALLOC_BUFFER at all,


Right, it doesn't yet address READING_FIRMWARE_PREALLOC_BUFFER, but
should.

Depending on whether the device requesting the firmware has access to
the DMA memory, before the signature verification, will determine how
IMA-appraisal addresses READING_FIRMWARE_PREALLOC_BUFFER.


Ah I see. So this probably means that the IMA integration for
my EFI embedded firmware code should also pass READING_FIRMWARE or
READING_FIRMWARE_PREALLOC_BUFFER depending on if a pre-allocated
buffer is used.

Hmm, the security_kernel_post_read_file() call in
drivers/base/firmware_loader/fallback.c

Unconditionally passes READING_FIRMWARE, it should probably check
fw_priv->is_paged_buf and base the id to pass on that.

And yes it is possible AFAICT for the firmware_request_into_buf()
method to fallback to the userspace helper, this can happen if the
fw_fallback_config.force_sysfs_fallback flag is set.

Regards,

Hans

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Hans de Goede]

Hi,

On 24-04-18 18:07, Mimi Zohar wrote:

On Tue, 2018-04-24 at 17:09 +0200, Hans de Goede wrote:

Hi,

On 23-04-18 23:11, Luis R. Rodriguez wrote:

Hans, please see use of READING_FIRMWARE_PREALLOC_BUFFER, we'll need a new ID
and security for this type of request so IMA can reject it if the policy is
configured for it.


Hmm, interesting, actually it seems like the whole existence
of READING_FIRMWARE_PREALLOC_BUFFER is a mistake, the IMA
framework really does not care if we are loading the firmware
into memory allocated by the firmware-loader code, or into
memory allocated by the device-driver requesting the firmware.

As such the current IMA code (from v4.17-rc2) actually does
not handle READING_FIRMWARE_PREALLOC_BUFFER at all,


Right, it doesn't yet address READING_FIRMWARE_PREALLOC_BUFFER, but
should.

Depending on whether the device requesting the firmware has access to
the DMA memory, before the signature verification, will determine how
IMA-appraisal addresses READING_FIRMWARE_PREALLOC_BUFFER.


Ah I see. So this probably means that the IMA integration for
my EFI embedded firmware code should also pass READING_FIRMWARE or
READING_FIRMWARE_PREALLOC_BUFFER depending on if a pre-allocated
buffer is used.

Hmm, the security_kernel_post_read_file() call in
drivers/base/firmware_loader/fallback.c

Unconditionally passes READING_FIRMWARE, it should probably check
fw_priv->is_paged_buf and base the id to pass on that.

And yes it is possible AFAICT for the firmware_request_into_buf()
method to fallback to the userspace helper, this can happen if the
fw_fallback_config.force_sysfs_fallback flag is set.

Regards,

Hans

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Mimi Zohar]

On Tue, 2018-04-24 at 17:09 +0200, Hans de Goede wrote:
> Hi,
> 
> On 23-04-18 23:11, Luis R. Rodriguez wrote:
> > Hans, please see use of READING_FIRMWARE_PREALLOC_BUFFER, we'll need a new 
> > ID
> > and security for this type of request so IMA can reject it if the policy is
> > configured for it.
> 
> Hmm, interesting, actually it seems like the whole existence
> of READING_FIRMWARE_PREALLOC_BUFFER is a mistake, the IMA
> framework really does not care if we are loading the firmware
> into memory allocated by the firmware-loader code, or into
> memory allocated by the device-driver requesting the firmware.
> 
> As such the current IMA code (from v4.17-rc2) actually does
> not handle READING_FIRMWARE_PREALLOC_BUFFER at all, 

Right, it doesn't yet address READING_FIRMWARE_PREALLOC_BUFFER, but
should.

Depending on whether the device requesting the firmware has access to
the DMA memory, before the signature verification, will determine how
IMA-appraisal addresses READING_FIRMWARE_PREALLOC_BUFFER.

Mimi

> here
> are bits of code from: security/integrity/ima/ima_main.c:
> 
> static int read_idmap[READING_MAX_ID] = {
>  [READING_FIRMWARE] = FIRMWARE_CHECK,
>  [READING_MODULE] = MODULE_CHECK,
>  [READING_KEXEC_IMAGE] = KEXEC_KERNEL_CHECK,
>  [READING_KEXEC_INITRAMFS] = KEXEC_INITRAMFS_CHECK,
>  [READING_POLICY] = POLICY_CHECK
> };
> 
> int ima_post_read_file(struct file *file, void *buf, loff_t size,
>   ...
>  if (!file && read_id == READING_FIRMWARE) {
>  if ((ima_appraise & IMA_APPRAISE_FIRMWARE) &&
>  (ima_appraise & IMA_APPRAISE_ENFORCE))
>  return -EACCES; /* INTEGRITY_UNKNOWN */
>  return 0;
>  }
> 
> Which show that the IMA code is not handling
> READING_FIRMWARE_PREALLOC_BUFFER as it should (I believe it
> should handle it the same as READING_FIRMWARE).
> 
> Now we could fix that, but the only user of
> READING_FIRMWARE_PREALLOC_BUFFER is the code which originally
> introduced it:
> 
> https://patchwork.kernel.org/patch/9162011/
> 
> So I believe it might be better to instead replace it
> with just READING_FIRMWARE and find another way to tell
> kernel_read_file() that there is a pre-allocated buffer,
> perhaps the easiest way there is that  *buf must be
> NULL when the caller wants kernel_read_file() to
> vmalloc the mem. This would of course require auditing
> all callers that the buf which the pass in is initialized
> to NULL.
> 
> Either way adding a third READING_FIRMWARE_FOO to the
> kernel_read_file_id enum seems like a bad idea, from
> the IMA pov firmware is firmware.
> 
> What this whole exercise has shown me though is that
> I need to call security_kernel_post_read_file() when
> loading EFI embedded firmware. I will add a call to
> security_kernel_post_read_file() for v4 of the patch-set.
> 
> > Please Cc Kees in future patches.
> 
> Will do.
> 
> Regards,
> 
> Hans
> 

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Mimi Zohar]

On Tue, 2018-04-24 at 17:09 +0200, Hans de Goede wrote:
> Hi,
> 
> On 23-04-18 23:11, Luis R. Rodriguez wrote:
> > Hans, please see use of READING_FIRMWARE_PREALLOC_BUFFER, we'll need a new 
> > ID
> > and security for this type of request so IMA can reject it if the policy is
> > configured for it.
> 
> Hmm, interesting, actually it seems like the whole existence
> of READING_FIRMWARE_PREALLOC_BUFFER is a mistake, the IMA
> framework really does not care if we are loading the firmware
> into memory allocated by the firmware-loader code, or into
> memory allocated by the device-driver requesting the firmware.
> 
> As such the current IMA code (from v4.17-rc2) actually does
> not handle READING_FIRMWARE_PREALLOC_BUFFER at all, 

Right, it doesn't yet address READING_FIRMWARE_PREALLOC_BUFFER, but
should.

Depending on whether the device requesting the firmware has access to
the DMA memory, before the signature verification, will determine how
IMA-appraisal addresses READING_FIRMWARE_PREALLOC_BUFFER.

Mimi

> here
> are bits of code from: security/integrity/ima/ima_main.c:
> 
> static int read_idmap[READING_MAX_ID] = {
>  [READING_FIRMWARE] = FIRMWARE_CHECK,
>  [READING_MODULE] = MODULE_CHECK,
>  [READING_KEXEC_IMAGE] = KEXEC_KERNEL_CHECK,
>  [READING_KEXEC_INITRAMFS] = KEXEC_INITRAMFS_CHECK,
>  [READING_POLICY] = POLICY_CHECK
> };
> 
> int ima_post_read_file(struct file *file, void *buf, loff_t size,
>   ...
>  if (!file && read_id == READING_FIRMWARE) {
>  if ((ima_appraise & IMA_APPRAISE_FIRMWARE) &&
>  (ima_appraise & IMA_APPRAISE_ENFORCE))
>  return -EACCES; /* INTEGRITY_UNKNOWN */
>  return 0;
>  }
> 
> Which show that the IMA code is not handling
> READING_FIRMWARE_PREALLOC_BUFFER as it should (I believe it
> should handle it the same as READING_FIRMWARE).
> 
> Now we could fix that, but the only user of
> READING_FIRMWARE_PREALLOC_BUFFER is the code which originally
> introduced it:
> 
> https://patchwork.kernel.org/patch/9162011/
> 
> So I believe it might be better to instead replace it
> with just READING_FIRMWARE and find another way to tell
> kernel_read_file() that there is a pre-allocated buffer,
> perhaps the easiest way there is that  *buf must be
> NULL when the caller wants kernel_read_file() to
> vmalloc the mem. This would of course require auditing
> all callers that the buf which the pass in is initialized
> to NULL.
> 
> Either way adding a third READING_FIRMWARE_FOO to the
> kernel_read_file_id enum seems like a bad idea, from
> the IMA pov firmware is firmware.
> 
> What this whole exercise has shown me though is that
> I need to call security_kernel_post_read_file() when
> loading EFI embedded firmware. I will add a call to
> security_kernel_post_read_file() for v4 of the patch-set.
> 
> > Please Cc Kees in future patches.
> 
> Will do.
> 
> Regards,
> 
> Hans
> 

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Hans de Goede]

Hi,

On 23-04-18 23:11, Luis R. Rodriguez wrote:

Hans, please see use of READING_FIRMWARE_PREALLOC_BUFFER, we'll need a new ID
and security for this type of request so IMA can reject it if the policy is
configured for it.


Hmm, interesting, actually it seems like the whole existence
of READING_FIRMWARE_PREALLOC_BUFFER is a mistake, the IMA
framework really does not care if we are loading the firmware
into memory allocated by the firmware-loader code, or into
memory allocated by the device-driver requesting the firmware.

As such the current IMA code (from v4.17-rc2) actually does
not handle READING_FIRMWARE_PREALLOC_BUFFER at all, here
are bits of code from: security/integrity/ima/ima_main.c:

static int read_idmap[READING_MAX_ID] = {
[READING_FIRMWARE] = FIRMWARE_CHECK,
[READING_MODULE] = MODULE_CHECK,
[READING_KEXEC_IMAGE] = KEXEC_KERNEL_CHECK,
[READING_KEXEC_INITRAMFS] = KEXEC_INITRAMFS_CHECK,
[READING_POLICY] = POLICY_CHECK
};

int ima_post_read_file(struct file *file, void *buf, loff_t size,
...
if (!file && read_id == READING_FIRMWARE) {
if ((ima_appraise & IMA_APPRAISE_FIRMWARE) &&
(ima_appraise & IMA_APPRAISE_ENFORCE))
return -EACCES; /* INTEGRITY_UNKNOWN */
return 0;
}

Which show that the IMA code is not handling
READING_FIRMWARE_PREALLOC_BUFFER as it should (I believe it
should handle it the same as READING_FIRMWARE).

Now we could fix that, but the only user of
READING_FIRMWARE_PREALLOC_BUFFER is the code which originally
introduced it:

https://patchwork.kernel.org/patch/9162011/

So I believe it might be better to instead replace it
with just READING_FIRMWARE and find another way to tell
kernel_read_file() that there is a pre-allocated buffer,
perhaps the easiest way there is that  *buf must be
NULL when the caller wants kernel_read_file() to
vmalloc the mem. This would of course require auditing
all callers that the buf which the pass in is initialized
to NULL.

Either way adding a third READING_FIRMWARE_FOO to the
kernel_read_file_id enum seems like a bad idea, from
the IMA pov firmware is firmware.

What this whole exercise has shown me though is that
I need to call security_kernel_post_read_file() when
loading EFI embedded firmware. I will add a call to
security_kernel_post_read_file() for v4 of the patch-set.


Please Cc Kees in future patches.


Will do.

Regards,

Hans

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Hans de Goede]

Hi,

On 23-04-18 23:11, Luis R. Rodriguez wrote:

Hans, please see use of READING_FIRMWARE_PREALLOC_BUFFER, we'll need a new ID
and security for this type of request so IMA can reject it if the policy is
configured for it.


Hmm, interesting, actually it seems like the whole existence
of READING_FIRMWARE_PREALLOC_BUFFER is a mistake, the IMA
framework really does not care if we are loading the firmware
into memory allocated by the firmware-loader code, or into
memory allocated by the device-driver requesting the firmware.

As such the current IMA code (from v4.17-rc2) actually does
not handle READING_FIRMWARE_PREALLOC_BUFFER at all, here
are bits of code from: security/integrity/ima/ima_main.c:

static int read_idmap[READING_MAX_ID] = {
[READING_FIRMWARE] = FIRMWARE_CHECK,
[READING_MODULE] = MODULE_CHECK,
[READING_KEXEC_IMAGE] = KEXEC_KERNEL_CHECK,
[READING_KEXEC_INITRAMFS] = KEXEC_INITRAMFS_CHECK,
[READING_POLICY] = POLICY_CHECK
};

int ima_post_read_file(struct file *file, void *buf, loff_t size,
...
if (!file && read_id == READING_FIRMWARE) {
if ((ima_appraise & IMA_APPRAISE_FIRMWARE) &&
(ima_appraise & IMA_APPRAISE_ENFORCE))
return -EACCES; /* INTEGRITY_UNKNOWN */
return 0;
}

Which show that the IMA code is not handling
READING_FIRMWARE_PREALLOC_BUFFER as it should (I believe it
should handle it the same as READING_FIRMWARE).

Now we could fix that, but the only user of
READING_FIRMWARE_PREALLOC_BUFFER is the code which originally
introduced it:

https://patchwork.kernel.org/patch/9162011/

So I believe it might be better to instead replace it
with just READING_FIRMWARE and find another way to tell
kernel_read_file() that there is a pre-allocated buffer,
perhaps the easiest way there is that  *buf must be
NULL when the caller wants kernel_read_file() to
vmalloc the mem. This would of course require auditing
all callers that the buf which the pass in is initialized
to NULL.

Either way adding a third READING_FIRMWARE_FOO to the
kernel_read_file_id enum seems like a bad idea, from
the IMA pov firmware is firmware.

What this whole exercise has shown me though is that
I need to call security_kernel_post_read_file() when
loading EFI embedded firmware. I will add a call to
security_kernel_post_read_file() for v4 of the patch-set.


Please Cc Kees in future patches.


Will do.

Regards,

Hans

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Hans de Goede]

Hi,

On 16-04-18 10:28, Ard Biesheuvel wrote:

On 8 April 2018 at 19:40, Hans de Goede  wrote:

Just like with PCI options ROMs, which we save in the setup_efi_pci*
functions from arch/x86/boot/compressed/eboot.c, the EFI code / ROM itself
sometimes may contain data which is useful/necessary for peripheral drivers
to have access to.

Specifically the EFI code may contain an embedded copy of firmware which
needs to be (re)loaded into the peripheral. Normally such firmware would be
part of linux-firmware, but in some cases this is not feasible, for 2
reasons:

1) The firmware is customized for a specific use-case of the chipset / use
with a specific hardware model, so we cannot have a single firmware file
for the chipset. E.g. touchscreen controller firmwares are compiled
specifically for the hardware model they are used with, as they are
calibrated for a specific model digitizer.

2) Despite repeated attempts we have failed to get permission to
redistribute the firmware. This is especially a problem with customized
firmwares, these get created by the chip vendor for a specific ODM and the
copyright may partially belong with the ODM, so the chip vendor cannot
give a blanket permission to distribute these.

This commit adds support for finding peripheral firmware embedded in the
EFI code and making this available to peripheral drivers through the
standard firmware loading mechanism.

Note we check the EFI_BOOT_SERVICES_CODE for embedded firmware near the end
of start_kernel(), just before calling rest_init(), this is on purpose
because the typical EFI_BOOT_SERVICES_CODE memory-segment is too large for
early_memremap(), so the check must be done after mm_init(). This relies
on EFI_BOOT_SERVICES_CODE not being free-ed until efi_free_boot_services()
is called, which means that this will only work on x86 for now.

Reported-by: Dave Olsthoorn 
Suggested-by: Peter Jones 
Signed-off-by: Hans de Goede 
---
Changes in v2:
-Rebased on driver-core/driver-core-next
-Add documentation describing the EFI embedded firmware mechanism to:
  Documentation/driver-api/firmware/request_firmware.rst
-Add a new EFI_EMBEDDED_FIRMWARE Kconfig bool and only build the embedded
  fw support if this is set. This is an invisible option which should be
  selected by drivers which need this
-Remove the efi_embedded_fw_desc and dmi_system_id-s for known devices
  from the efi-embedded-fw code, instead drivers using this are expected to
  export a dmi_system_id array, with each entries' driver_data pointing to a
  efi_embedded_fw_desc struct and register this with the efi-embedded-fw code
-Use kmemdup to make a copy instead of efi_mem_reserve()-ing the firmware,
  this avoids us messing with the EFI memmap and avoids the need to make
  changes to efi_mem_desc_lookup()
-Make the firmware-loader code only fallback to efi_get_embedded_fw() if the
  passed in device has the "efi-embedded-firmware" device-property bool set
-Skip usermodehelper fallback when "efi-embedded-firmware" device-property
  is set

Changes in v3:
-Fix the docs using "efi-embedded-fw" as property name instead of
  "efi-embedded-firmware"
---
  .../driver-api/firmware/request_firmware.rst  |  70 +
  drivers/base/firmware_loader/main.c   |  33 
  drivers/firmware/efi/Kconfig  |   6 +
  drivers/firmware/efi/Makefile |   1 +
  drivers/firmware/efi/embedded-firmware.c  | 148 ++
  include/linux/efi.h   |   6 +
  include/linux/efi_embedded_fw.h   |  25 +++
  init/main.c   |   1 +
  8 files changed, 290 insertions(+)
  create mode 100644 drivers/firmware/efi/embedded-firmware.c
  create mode 100644 include/linux/efi_embedded_fw.h

diff --git a/Documentation/driver-api/firmware/request_firmware.rst 
b/Documentation/driver-api/firmware/request_firmware.rst
index 20f21ed427a5..189b02f815c9 100644
--- a/Documentation/driver-api/firmware/request_firmware.rst
+++ b/Documentation/driver-api/firmware/request_firmware.rst
@@ -68,3 +68,73 @@ If something went wrong request_firmware() returns non-zero 
and fw_entry
  is set to NULL. Once your driver is done with processing the firmware it
  can call call release_firmware(fw_entry) to release the firmware image
  and any related resource.
+
+EFI embedded firmware support
+=
+
+On some devices the system's EFI code / ROM may contain an embedded copy
+of firmware for some of the system's integrated peripheral devices and
+the peripheral's Linux device-driver needs to access this firmware.
+
+A device driver which needs this can describe the firmware it needs
+using an efi_embedded_fw_desc struct:
+
+.. kernel-doc:: include/linux/efi_embedded_fw.h
+   :functions: efi_embedded_fw_desc
+
+The EFI embedded-fw code works by scanning all EFI_BOOT_SERVICES_CODE memory
+segments for an eight byte sequence 

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Hans de Goede]

Hi,

On 16-04-18 10:28, Ard Biesheuvel wrote:

On 8 April 2018 at 19:40, Hans de Goede  wrote:

Just like with PCI options ROMs, which we save in the setup_efi_pci*
functions from arch/x86/boot/compressed/eboot.c, the EFI code / ROM itself
sometimes may contain data which is useful/necessary for peripheral drivers
to have access to.

Specifically the EFI code may contain an embedded copy of firmware which
needs to be (re)loaded into the peripheral. Normally such firmware would be
part of linux-firmware, but in some cases this is not feasible, for 2
reasons:

1) The firmware is customized for a specific use-case of the chipset / use
with a specific hardware model, so we cannot have a single firmware file
for the chipset. E.g. touchscreen controller firmwares are compiled
specifically for the hardware model they are used with, as they are
calibrated for a specific model digitizer.

2) Despite repeated attempts we have failed to get permission to
redistribute the firmware. This is especially a problem with customized
firmwares, these get created by the chip vendor for a specific ODM and the
copyright may partially belong with the ODM, so the chip vendor cannot
give a blanket permission to distribute these.

This commit adds support for finding peripheral firmware embedded in the
EFI code and making this available to peripheral drivers through the
standard firmware loading mechanism.

Note we check the EFI_BOOT_SERVICES_CODE for embedded firmware near the end
of start_kernel(), just before calling rest_init(), this is on purpose
because the typical EFI_BOOT_SERVICES_CODE memory-segment is too large for
early_memremap(), so the check must be done after mm_init(). This relies
on EFI_BOOT_SERVICES_CODE not being free-ed until efi_free_boot_services()
is called, which means that this will only work on x86 for now.

Reported-by: Dave Olsthoorn 
Suggested-by: Peter Jones 
Signed-off-by: Hans de Goede 
---
Changes in v2:
-Rebased on driver-core/driver-core-next
-Add documentation describing the EFI embedded firmware mechanism to:
  Documentation/driver-api/firmware/request_firmware.rst
-Add a new EFI_EMBEDDED_FIRMWARE Kconfig bool and only build the embedded
  fw support if this is set. This is an invisible option which should be
  selected by drivers which need this
-Remove the efi_embedded_fw_desc and dmi_system_id-s for known devices
  from the efi-embedded-fw code, instead drivers using this are expected to
  export a dmi_system_id array, with each entries' driver_data pointing to a
  efi_embedded_fw_desc struct and register this with the efi-embedded-fw code
-Use kmemdup to make a copy instead of efi_mem_reserve()-ing the firmware,
  this avoids us messing with the EFI memmap and avoids the need to make
  changes to efi_mem_desc_lookup()
-Make the firmware-loader code only fallback to efi_get_embedded_fw() if the
  passed in device has the "efi-embedded-firmware" device-property bool set
-Skip usermodehelper fallback when "efi-embedded-firmware" device-property
  is set

Changes in v3:
-Fix the docs using "efi-embedded-fw" as property name instead of
  "efi-embedded-firmware"
---
  .../driver-api/firmware/request_firmware.rst  |  70 +
  drivers/base/firmware_loader/main.c   |  33 
  drivers/firmware/efi/Kconfig  |   6 +
  drivers/firmware/efi/Makefile |   1 +
  drivers/firmware/efi/embedded-firmware.c  | 148 ++
  include/linux/efi.h   |   6 +
  include/linux/efi_embedded_fw.h   |  25 +++
  init/main.c   |   1 +
  8 files changed, 290 insertions(+)
  create mode 100644 drivers/firmware/efi/embedded-firmware.c
  create mode 100644 include/linux/efi_embedded_fw.h

diff --git a/Documentation/driver-api/firmware/request_firmware.rst 
b/Documentation/driver-api/firmware/request_firmware.rst
index 20f21ed427a5..189b02f815c9 100644
--- a/Documentation/driver-api/firmware/request_firmware.rst
+++ b/Documentation/driver-api/firmware/request_firmware.rst
@@ -68,3 +68,73 @@ If something went wrong request_firmware() returns non-zero 
and fw_entry
  is set to NULL. Once your driver is done with processing the firmware it
  can call call release_firmware(fw_entry) to release the firmware image
  and any related resource.
+
+EFI embedded firmware support
+=
+
+On some devices the system's EFI code / ROM may contain an embedded copy
+of firmware for some of the system's integrated peripheral devices and
+the peripheral's Linux device-driver needs to access this firmware.
+
+A device driver which needs this can describe the firmware it needs
+using an efi_embedded_fw_desc struct:
+
+.. kernel-doc:: include/linux/efi_embedded_fw.h
+   :functions: efi_embedded_fw_desc
+
+The EFI embedded-fw code works by scanning all EFI_BOOT_SERVICES_CODE memory
+segments for an eight byte sequence matching prefix, if the prefix is found it
+then does a crc32 over length bytes 

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Luis R. Rodriguez]

Hans, please see use of READING_FIRMWARE_PREALLOC_BUFFER, we'll need a new ID
and security for this type of request so IMA can reject it if the policy is
configured for it.

Please Cc Kees in future patches.

  Luis

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Luis R. Rodriguez]

Hans, please see use of READING_FIRMWARE_PREALLOC_BUFFER, we'll need a new ID
and security for this type of request so IMA can reject it if the policy is
configured for it.

Please Cc Kees in future patches.

  Luis

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Hans de Goede]

Hi,

On 17-04-18 02:17, Luis R. Rodriguez wrote:

On Sun, Apr 08, 2018 at 07:40:11PM +0200, Hans de Goede wrote:

  static void firmware_free_data(const struct firmware *fw)
  {
@@ -576,6 +600,15 @@ _request_firmware(const struct firmware **firmware_p, 
const char *name,
goto out;
  
  	ret = fw_get_filesystem_firmware(device, fw->priv);

+#ifdef CONFIG_EFI_EMBEDDED_FIRMWARE
+   if (ret && device &&
+   device_property_read_bool(device, "efi-embedded-firmware")) {
+   ret = fw_get_efi_embedded_fw(device, fw->priv, ret);
+   if (ret == 0)
+   ret = assign_fw(fw, device, opt_flags | FW_OPT_NOCACHE);
+   goto out;
+   }
+#endif




So thinking some more about this, I can put the device_property check
inside the fw_get_efi_embedded_fw() call, as well as modify opt_flags
there to or in FW_OPT_NOCACHE on success, then together with the discussed
changed to drop the #ifdef, the code would look like this:

ret = fw_get_filesystem_firmware(device, fw->priv);
if (ret)
fw_get_efi_embedded_fw(device, fw->priv, _flags, ret);
if (ret)
if (!(opt_flags & FW_OPT_NO_WARN))
dev_warn(device,
...

With just these 2 lines being new:

if (ret)
fw_get_efi_embedded_fw(device, fw->priv, _flags, ret);

So the main.c changes will be nice and clean then.

Regards,

Hans

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Hans de Goede]

Hi,

On 17-04-18 02:17, Luis R. Rodriguez wrote:

On Sun, Apr 08, 2018 at 07:40:11PM +0200, Hans de Goede wrote:

  static void firmware_free_data(const struct firmware *fw)
  {
@@ -576,6 +600,15 @@ _request_firmware(const struct firmware **firmware_p, 
const char *name,
goto out;
  
  	ret = fw_get_filesystem_firmware(device, fw->priv);

+#ifdef CONFIG_EFI_EMBEDDED_FIRMWARE
+   if (ret && device &&
+   device_property_read_bool(device, "efi-embedded-firmware")) {
+   ret = fw_get_efi_embedded_fw(device, fw->priv, ret);
+   if (ret == 0)
+   ret = assign_fw(fw, device, opt_flags | FW_OPT_NOCACHE);
+   goto out;
+   }
+#endif




So thinking some more about this, I can put the device_property check
inside the fw_get_efi_embedded_fw() call, as well as modify opt_flags
there to or in FW_OPT_NOCACHE on success, then together with the discussed
changed to drop the #ifdef, the code would look like this:

ret = fw_get_filesystem_firmware(device, fw->priv);
if (ret)
fw_get_efi_embedded_fw(device, fw->priv, _flags, ret);
if (ret)
if (!(opt_flags & FW_OPT_NO_WARN))
dev_warn(device,
...

With just these 2 lines being new:

if (ret)
fw_get_efi_embedded_fw(device, fw->priv, _flags, ret);

So the main.c changes will be nice and clean then.

Regards,

Hans

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Hans de Goede]

Hi,

On 17-04-18 02:17, Luis R. Rodriguez wrote:

On Sun, Apr 08, 2018 at 07:40:11PM +0200, Hans de Goede wrote:

  static void firmware_free_data(const struct firmware *fw)
  {
@@ -576,6 +600,15 @@ _request_firmware(const struct firmware **firmware_p, 
const char *name,
goto out;
  
  	ret = fw_get_filesystem_firmware(device, fw->priv);

+#ifdef CONFIG_EFI_EMBEDDED_FIRMWARE
+   if (ret && device &&
+   device_property_read_bool(device, "efi-embedded-firmware")) {
+   ret = fw_get_efi_embedded_fw(device, fw->priv, ret);
+   if (ret == 0)
+   ret = assign_fw(fw, device, opt_flags | FW_OPT_NOCACHE);
+   goto out;
+   }
+#endif


You mussed what I asked for in terms of adding a new flag, (please work on top
of Andre's patches as those likely will be merged first, and also have kdocs
for the flags)


Ok I will base my next version on top of Andres' series.


and then a new firmware API to wrap the above into a function
which would only do something if the driver *asked* for it on their firmware
API call.
Ie, please add a new firmware_request_efi_fw().


As I tried to explain in the changelog the problem with doing this, is that
this makes it a driver decision, where it really needs to be platform-code 
driven,
not driver driven.

Take for example the drivers/input/touchscreen/silead.c code that is used on
a lot of 32 bit ARM platforms too, which don't have EFI at all, so if that
needs to call request_firmware_efi() then should I add:

#ifdef CONFIG_X86
fw = request_firmware_efi(...);
#else
fw = request_firmware(...);
#endif

? But even on x86 only some devices with a silead touchscreen have EFI
embedded firmware, so then I would need something like:

#ifdef CONFIG_X86
if (device_property_get_bool(dev, "some-prop-name"))
fw = request_firmware_efi(...);
else
#else
fw = request_firmware(...);
#endif

That is assuming I still want the normal fallback path in the
case no EFI firmware is available, which I do because then
something like packagekit may see if the firmware is packaged
in one of the configured distro repositories.

We already have (x86) platform code in place to attach
properties (like a board specific firmware filename) to the
device using device-properties so that drivers like silead.c
don't get filled / polluted with board/platform specific knowledge,
which IMHO is the place where the knowledge fallback to
an EFI embedded firmware copy belongs.

As the further patches in v3 of this series shows, this actually
works quite nicely, because this also allows bundling the
EFI-embedded firmware info (prefix, length, crc, name) together
with the other board specific properties.

TL;DR: using request_firmware_efi() vs request_firmware() is
a driver decision, but whether EFI firmware fallback should be
is board/platform specific not driver specific, therefor I
believe that using a device-property to signal this is better.


If you insist on me adding a request_firmware_efi() I can give
this a shot, but I know that Dmitry (the input maintainer) will
very much dislike the silead.c changes that implies...

Still a question for lets sat we go that route, what do we
then do with request_firmware_efi() when CONFIG_EFI is not set ?
Should it be defined then or not, and if it should be defined
when CONFIG_EFI is not set what should it do then?


Also if you see the
work I've done to remove the ifdefs over fallback mechanism you'll see it helps
split code and make it easier to read. We should strive to not add any more
ifdefery and instead make tehis code read easily.


So looking at how the CONFIG_FW_LOADER_USER_HELPER stuff deals
with this, I should:

1) Move the definition of fw_get_efi_embedded_fw() to a new
drivers/base/firmware_loader/fallback_efi.c,
which only gets build if CONFIG_EFI_EMBEDDED_FIRMWARE is set

2) Put the following in fallback.h:

#ifdef CONFIG_EFI_EMBEDDED_FIRMWARE
int fw_get_efi_embedded_fw(struct device *dev, struct fw_priv *fw_priv, int 
ret);
#else
static inline int
fw_get_efi_embedded_fw(struct device *dev, struct fw_priv *fw_priv, int ret)
{
return ret;
}
#endif

have I got that right?

Regards,

Hans

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Hans de Goede]

Hi,

On 17-04-18 02:17, Luis R. Rodriguez wrote:

On Sun, Apr 08, 2018 at 07:40:11PM +0200, Hans de Goede wrote:

  static void firmware_free_data(const struct firmware *fw)
  {
@@ -576,6 +600,15 @@ _request_firmware(const struct firmware **firmware_p, 
const char *name,
goto out;
  
  	ret = fw_get_filesystem_firmware(device, fw->priv);

+#ifdef CONFIG_EFI_EMBEDDED_FIRMWARE
+   if (ret && device &&
+   device_property_read_bool(device, "efi-embedded-firmware")) {
+   ret = fw_get_efi_embedded_fw(device, fw->priv, ret);
+   if (ret == 0)
+   ret = assign_fw(fw, device, opt_flags | FW_OPT_NOCACHE);
+   goto out;
+   }
+#endif


You mussed what I asked for in terms of adding a new flag, (please work on top
of Andre's patches as those likely will be merged first, and also have kdocs
for the flags)


Ok I will base my next version on top of Andres' series.


and then a new firmware API to wrap the above into a function
which would only do something if the driver *asked* for it on their firmware
API call.
Ie, please add a new firmware_request_efi_fw().


As I tried to explain in the changelog the problem with doing this, is that
this makes it a driver decision, where it really needs to be platform-code 
driven,
not driver driven.

Take for example the drivers/input/touchscreen/silead.c code that is used on
a lot of 32 bit ARM platforms too, which don't have EFI at all, so if that
needs to call request_firmware_efi() then should I add:

#ifdef CONFIG_X86
fw = request_firmware_efi(...);
#else
fw = request_firmware(...);
#endif

? But even on x86 only some devices with a silead touchscreen have EFI
embedded firmware, so then I would need something like:

#ifdef CONFIG_X86
if (device_property_get_bool(dev, "some-prop-name"))
fw = request_firmware_efi(...);
else
#else
fw = request_firmware(...);
#endif

That is assuming I still want the normal fallback path in the
case no EFI firmware is available, which I do because then
something like packagekit may see if the firmware is packaged
in one of the configured distro repositories.

We already have (x86) platform code in place to attach
properties (like a board specific firmware filename) to the
device using device-properties so that drivers like silead.c
don't get filled / polluted with board/platform specific knowledge,
which IMHO is the place where the knowledge fallback to
an EFI embedded firmware copy belongs.

As the further patches in v3 of this series shows, this actually
works quite nicely, because this also allows bundling the
EFI-embedded firmware info (prefix, length, crc, name) together
with the other board specific properties.

TL;DR: using request_firmware_efi() vs request_firmware() is
a driver decision, but whether EFI firmware fallback should be
is board/platform specific not driver specific, therefor I
believe that using a device-property to signal this is better.


If you insist on me adding a request_firmware_efi() I can give
this a shot, but I know that Dmitry (the input maintainer) will
very much dislike the silead.c changes that implies...

Still a question for lets sat we go that route, what do we
then do with request_firmware_efi() when CONFIG_EFI is not set ?
Should it be defined then or not, and if it should be defined
when CONFIG_EFI is not set what should it do then?


Also if you see the
work I've done to remove the ifdefs over fallback mechanism you'll see it helps
split code and make it easier to read. We should strive to not add any more
ifdefery and instead make tehis code read easily.


So looking at how the CONFIG_FW_LOADER_USER_HELPER stuff deals
with this, I should:

1) Move the definition of fw_get_efi_embedded_fw() to a new
drivers/base/firmware_loader/fallback_efi.c,
which only gets build if CONFIG_EFI_EMBEDDED_FIRMWARE is set

2) Put the following in fallback.h:

#ifdef CONFIG_EFI_EMBEDDED_FIRMWARE
int fw_get_efi_embedded_fw(struct device *dev, struct fw_priv *fw_priv, int 
ret);
#else
static inline int
fw_get_efi_embedded_fw(struct device *dev, struct fw_priv *fw_priv, int ret)
{
return ret;
}
#endif

have I got that right?

Regards,

Hans

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Luis R. Rodriguez]

On Sun, Apr 08, 2018 at 07:40:11PM +0200, Hans de Goede wrote:
>  static void firmware_free_data(const struct firmware *fw)
>  {
> @@ -576,6 +600,15 @@ _request_firmware(const struct firmware **firmware_p, 
> const char *name,
>   goto out;
>  
>   ret = fw_get_filesystem_firmware(device, fw->priv);
> +#ifdef CONFIG_EFI_EMBEDDED_FIRMWARE
> + if (ret && device &&
> + device_property_read_bool(device, "efi-embedded-firmware")) {
> + ret = fw_get_efi_embedded_fw(device, fw->priv, ret);
> + if (ret == 0)
> + ret = assign_fw(fw, device, opt_flags | FW_OPT_NOCACHE);
> + goto out;
> + }
> +#endif

You mussed what I asked for in terms of adding a new flag, (please work on top
of Andre's patches as those likely will be merged first, and also have kdocs
for the flags) and then a new firmware API to wrap the above into a function
which would only do something if the driver *asked* for it on their firmware
API call.  Ie, please add a new firmware_request_efi_fw(). Also if you see the
work I've done to remove the ifdefs over fallback mechanism you'll see it helps
split code and make it easier to read. We should strive to not add any more
ifdefery and instead make tehis code read easily.

  Luis

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Luis R. Rodriguez]

On Sun, Apr 08, 2018 at 07:40:11PM +0200, Hans de Goede wrote:
>  static void firmware_free_data(const struct firmware *fw)
>  {
> @@ -576,6 +600,15 @@ _request_firmware(const struct firmware **firmware_p, 
> const char *name,
>   goto out;
>  
>   ret = fw_get_filesystem_firmware(device, fw->priv);
> +#ifdef CONFIG_EFI_EMBEDDED_FIRMWARE
> + if (ret && device &&
> + device_property_read_bool(device, "efi-embedded-firmware")) {
> + ret = fw_get_efi_embedded_fw(device, fw->priv, ret);
> + if (ret == 0)
> + ret = assign_fw(fw, device, opt_flags | FW_OPT_NOCACHE);
> + goto out;
> + }
> +#endif

You mussed what I asked for in terms of adding a new flag, (please work on top
of Andre's patches as those likely will be merged first, and also have kdocs
for the flags) and then a new firmware API to wrap the above into a function
which would only do something if the driver *asked* for it on their firmware
API call.  Ie, please add a new firmware_request_efi_fw(). Also if you see the
work I've done to remove the ifdefs over fallback mechanism you'll see it helps
split code and make it easier to read. We should strive to not add any more
ifdefery and instead make tehis code read easily.

  Luis

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Ard Biesheuvel]

On 8 April 2018 at 19:40, Hans de Goede  wrote:
> Just like with PCI options ROMs, which we save in the setup_efi_pci*
> functions from arch/x86/boot/compressed/eboot.c, the EFI code / ROM itself
> sometimes may contain data which is useful/necessary for peripheral drivers
> to have access to.
>
> Specifically the EFI code may contain an embedded copy of firmware which
> needs to be (re)loaded into the peripheral. Normally such firmware would be
> part of linux-firmware, but in some cases this is not feasible, for 2
> reasons:
>
> 1) The firmware is customized for a specific use-case of the chipset / use
> with a specific hardware model, so we cannot have a single firmware file
> for the chipset. E.g. touchscreen controller firmwares are compiled
> specifically for the hardware model they are used with, as they are
> calibrated for a specific model digitizer.
>
> 2) Despite repeated attempts we have failed to get permission to
> redistribute the firmware. This is especially a problem with customized
> firmwares, these get created by the chip vendor for a specific ODM and the
> copyright may partially belong with the ODM, so the chip vendor cannot
> give a blanket permission to distribute these.
>
> This commit adds support for finding peripheral firmware embedded in the
> EFI code and making this available to peripheral drivers through the
> standard firmware loading mechanism.
>
> Note we check the EFI_BOOT_SERVICES_CODE for embedded firmware near the end
> of start_kernel(), just before calling rest_init(), this is on purpose
> because the typical EFI_BOOT_SERVICES_CODE memory-segment is too large for
> early_memremap(), so the check must be done after mm_init(). This relies
> on EFI_BOOT_SERVICES_CODE not being free-ed until efi_free_boot_services()
> is called, which means that this will only work on x86 for now.
>
> Reported-by: Dave Olsthoorn 
> Suggested-by: Peter Jones 
> Signed-off-by: Hans de Goede 
> ---
> Changes in v2:
> -Rebased on driver-core/driver-core-next
> -Add documentation describing the EFI embedded firmware mechanism to:
>  Documentation/driver-api/firmware/request_firmware.rst
> -Add a new EFI_EMBEDDED_FIRMWARE Kconfig bool and only build the embedded
>  fw support if this is set. This is an invisible option which should be
>  selected by drivers which need this
> -Remove the efi_embedded_fw_desc and dmi_system_id-s for known devices
>  from the efi-embedded-fw code, instead drivers using this are expected to
>  export a dmi_system_id array, with each entries' driver_data pointing to a
>  efi_embedded_fw_desc struct and register this with the efi-embedded-fw code
> -Use kmemdup to make a copy instead of efi_mem_reserve()-ing the firmware,
>  this avoids us messing with the EFI memmap and avoids the need to make
>  changes to efi_mem_desc_lookup()
> -Make the firmware-loader code only fallback to efi_get_embedded_fw() if the
>  passed in device has the "efi-embedded-firmware" device-property bool set
> -Skip usermodehelper fallback when "efi-embedded-firmware" device-property
>  is set
>
> Changes in v3:
> -Fix the docs using "efi-embedded-fw" as property name instead of
>  "efi-embedded-firmware"
> ---
>  .../driver-api/firmware/request_firmware.rst  |  70 +
>  drivers/base/firmware_loader/main.c   |  33 
>  drivers/firmware/efi/Kconfig  |   6 +
>  drivers/firmware/efi/Makefile |   1 +
>  drivers/firmware/efi/embedded-firmware.c  | 148 ++
>  include/linux/efi.h   |   6 +
>  include/linux/efi_embedded_fw.h   |  25 +++
>  init/main.c   |   1 +
>  8 files changed, 290 insertions(+)
>  create mode 100644 drivers/firmware/efi/embedded-firmware.c
>  create mode 100644 include/linux/efi_embedded_fw.h
>
> diff --git a/Documentation/driver-api/firmware/request_firmware.rst 
> b/Documentation/driver-api/firmware/request_firmware.rst
> index 20f21ed427a5..189b02f815c9 100644
> --- a/Documentation/driver-api/firmware/request_firmware.rst
> +++ b/Documentation/driver-api/firmware/request_firmware.rst
> @@ -68,3 +68,73 @@ If something went wrong request_firmware() returns 
> non-zero and fw_entry
>  is set to NULL. Once your driver is done with processing the firmware it
>  can call call release_firmware(fw_entry) to release the firmware image
>  and any related resource.
> +
> +EFI embedded firmware support
> +=
> +
> +On some devices the system's EFI code / ROM may contain an embedded copy
> +of firmware for some of the system's integrated peripheral devices and
> +the peripheral's Linux device-driver needs to access this firmware.
> +
> +A device driver which needs this can describe the firmware it needs
> +using an efi_embedded_fw_desc struct:
> +
> +.. kernel-doc:: include/linux/efi_embedded_fw.h
> +   :functions: efi_embedded_fw_desc
> +
> +The EFI 

Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Ard Biesheuvel]

On 8 April 2018 at 19:40, Hans de Goede  wrote:
> Just like with PCI options ROMs, which we save in the setup_efi_pci*
> functions from arch/x86/boot/compressed/eboot.c, the EFI code / ROM itself
> sometimes may contain data which is useful/necessary for peripheral drivers
> to have access to.
>
> Specifically the EFI code may contain an embedded copy of firmware which
> needs to be (re)loaded into the peripheral. Normally such firmware would be
> part of linux-firmware, but in some cases this is not feasible, for 2
> reasons:
>
> 1) The firmware is customized for a specific use-case of the chipset / use
> with a specific hardware model, so we cannot have a single firmware file
> for the chipset. E.g. touchscreen controller firmwares are compiled
> specifically for the hardware model they are used with, as they are
> calibrated for a specific model digitizer.
>
> 2) Despite repeated attempts we have failed to get permission to
> redistribute the firmware. This is especially a problem with customized
> firmwares, these get created by the chip vendor for a specific ODM and the
> copyright may partially belong with the ODM, so the chip vendor cannot
> give a blanket permission to distribute these.
>
> This commit adds support for finding peripheral firmware embedded in the
> EFI code and making this available to peripheral drivers through the
> standard firmware loading mechanism.
>
> Note we check the EFI_BOOT_SERVICES_CODE for embedded firmware near the end
> of start_kernel(), just before calling rest_init(), this is on purpose
> because the typical EFI_BOOT_SERVICES_CODE memory-segment is too large for
> early_memremap(), so the check must be done after mm_init(). This relies
> on EFI_BOOT_SERVICES_CODE not being free-ed until efi_free_boot_services()
> is called, which means that this will only work on x86 for now.
>
> Reported-by: Dave Olsthoorn 
> Suggested-by: Peter Jones 
> Signed-off-by: Hans de Goede 
> ---
> Changes in v2:
> -Rebased on driver-core/driver-core-next
> -Add documentation describing the EFI embedded firmware mechanism to:
>  Documentation/driver-api/firmware/request_firmware.rst
> -Add a new EFI_EMBEDDED_FIRMWARE Kconfig bool and only build the embedded
>  fw support if this is set. This is an invisible option which should be
>  selected by drivers which need this
> -Remove the efi_embedded_fw_desc and dmi_system_id-s for known devices
>  from the efi-embedded-fw code, instead drivers using this are expected to
>  export a dmi_system_id array, with each entries' driver_data pointing to a
>  efi_embedded_fw_desc struct and register this with the efi-embedded-fw code
> -Use kmemdup to make a copy instead of efi_mem_reserve()-ing the firmware,
>  this avoids us messing with the EFI memmap and avoids the need to make
>  changes to efi_mem_desc_lookup()
> -Make the firmware-loader code only fallback to efi_get_embedded_fw() if the
>  passed in device has the "efi-embedded-firmware" device-property bool set
> -Skip usermodehelper fallback when "efi-embedded-firmware" device-property
>  is set
>
> Changes in v3:
> -Fix the docs using "efi-embedded-fw" as property name instead of
>  "efi-embedded-firmware"
> ---
>  .../driver-api/firmware/request_firmware.rst  |  70 +
>  drivers/base/firmware_loader/main.c   |  33 
>  drivers/firmware/efi/Kconfig  |   6 +
>  drivers/firmware/efi/Makefile |   1 +
>  drivers/firmware/efi/embedded-firmware.c  | 148 ++
>  include/linux/efi.h   |   6 +
>  include/linux/efi_embedded_fw.h   |  25 +++
>  init/main.c   |   1 +
>  8 files changed, 290 insertions(+)
>  create mode 100644 drivers/firmware/efi/embedded-firmware.c
>  create mode 100644 include/linux/efi_embedded_fw.h
>
> diff --git a/Documentation/driver-api/firmware/request_firmware.rst 
> b/Documentation/driver-api/firmware/request_firmware.rst
> index 20f21ed427a5..189b02f815c9 100644
> --- a/Documentation/driver-api/firmware/request_firmware.rst
> +++ b/Documentation/driver-api/firmware/request_firmware.rst
> @@ -68,3 +68,73 @@ If something went wrong request_firmware() returns 
> non-zero and fw_entry
>  is set to NULL. Once your driver is done with processing the firmware it
>  can call call release_firmware(fw_entry) to release the firmware image
>  and any related resource.
> +
> +EFI embedded firmware support
> +=
> +
> +On some devices the system's EFI code / ROM may contain an embedded copy
> +of firmware for some of the system's integrated peripheral devices and
> +the peripheral's Linux device-driver needs to access this firmware.
> +
> +A device driver which needs this can describe the firmware it needs
> +using an efi_embedded_fw_desc struct:
> +
> +.. kernel-doc:: include/linux/efi_embedded_fw.h
> +   :functions: efi_embedded_fw_desc
> +
> +The EFI embedded-fw code works by scanning all EFI_BOOT_SERVICES_CODE memory
> 

[PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Hans de Goede]

Just like with PCI options ROMs, which we save in the setup_efi_pci*
functions from arch/x86/boot/compressed/eboot.c, the EFI code / ROM itself
sometimes may contain data which is useful/necessary for peripheral drivers
to have access to.

Specifically the EFI code may contain an embedded copy of firmware which
needs to be (re)loaded into the peripheral. Normally such firmware would be
part of linux-firmware, but in some cases this is not feasible, for 2
reasons:

1) The firmware is customized for a specific use-case of the chipset / use
with a specific hardware model, so we cannot have a single firmware file
for the chipset. E.g. touchscreen controller firmwares are compiled
specifically for the hardware model they are used with, as they are
calibrated for a specific model digitizer.

2) Despite repeated attempts we have failed to get permission to
redistribute the firmware. This is especially a problem with customized
firmwares, these get created by the chip vendor for a specific ODM and the
copyright may partially belong with the ODM, so the chip vendor cannot
give a blanket permission to distribute these.

This commit adds support for finding peripheral firmware embedded in the
EFI code and making this available to peripheral drivers through the
standard firmware loading mechanism.

Note we check the EFI_BOOT_SERVICES_CODE for embedded firmware near the end
of start_kernel(), just before calling rest_init(), this is on purpose
because the typical EFI_BOOT_SERVICES_CODE memory-segment is too large for
early_memremap(), so the check must be done after mm_init(). This relies
on EFI_BOOT_SERVICES_CODE not being free-ed until efi_free_boot_services()
is called, which means that this will only work on x86 for now.

Reported-by: Dave Olsthoorn 
Suggested-by: Peter Jones 
Signed-off-by: Hans de Goede 
---
Changes in v2:
-Rebased on driver-core/driver-core-next
-Add documentation describing the EFI embedded firmware mechanism to:
 Documentation/driver-api/firmware/request_firmware.rst
-Add a new EFI_EMBEDDED_FIRMWARE Kconfig bool and only build the embedded
 fw support if this is set. This is an invisible option which should be
 selected by drivers which need this
-Remove the efi_embedded_fw_desc and dmi_system_id-s for known devices
 from the efi-embedded-fw code, instead drivers using this are expected to
 export a dmi_system_id array, with each entries' driver_data pointing to a
 efi_embedded_fw_desc struct and register this with the efi-embedded-fw code
-Use kmemdup to make a copy instead of efi_mem_reserve()-ing the firmware,
 this avoids us messing with the EFI memmap and avoids the need to make
 changes to efi_mem_desc_lookup()
-Make the firmware-loader code only fallback to efi_get_embedded_fw() if the
 passed in device has the "efi-embedded-firmware" device-property bool set
-Skip usermodehelper fallback when "efi-embedded-firmware" device-property
 is set

Changes in v3:
-Fix the docs using "efi-embedded-fw" as property name instead of
 "efi-embedded-firmware"
---
 .../driver-api/firmware/request_firmware.rst  |  70 +
 drivers/base/firmware_loader/main.c   |  33 
 drivers/firmware/efi/Kconfig  |   6 +
 drivers/firmware/efi/Makefile |   1 +
 drivers/firmware/efi/embedded-firmware.c  | 148 ++
 include/linux/efi.h   |   6 +
 include/linux/efi_embedded_fw.h   |  25 +++
 init/main.c   |   1 +
 8 files changed, 290 insertions(+)
 create mode 100644 drivers/firmware/efi/embedded-firmware.c
 create mode 100644 include/linux/efi_embedded_fw.h

diff --git a/Documentation/driver-api/firmware/request_firmware.rst 
b/Documentation/driver-api/firmware/request_firmware.rst
index 20f21ed427a5..189b02f815c9 100644
--- a/Documentation/driver-api/firmware/request_firmware.rst
+++ b/Documentation/driver-api/firmware/request_firmware.rst
@@ -68,3 +68,73 @@ If something went wrong request_firmware() returns non-zero 
and fw_entry
 is set to NULL. Once your driver is done with processing the firmware it
 can call call release_firmware(fw_entry) to release the firmware image
 and any related resource.
+
+EFI embedded firmware support
+=
+
+On some devices the system's EFI code / ROM may contain an embedded copy
+of firmware for some of the system's integrated peripheral devices and
+the peripheral's Linux device-driver needs to access this firmware.
+
+A device driver which needs this can describe the firmware it needs
+using an efi_embedded_fw_desc struct:
+
+.. kernel-doc:: include/linux/efi_embedded_fw.h
+   :functions: efi_embedded_fw_desc
+
+The EFI embedded-fw code works by scanning all EFI_BOOT_SERVICES_CODE memory
+segments for an eight byte sequence matching prefix, if the prefix is found it
+then does a crc32 over length bytes and if that matches makes a copy of length
+bytes and adds that to 

[PATCH v3 2/5] efi: Add embedded peripheral firmware support

[Hans de Goede]

Just like with PCI options ROMs, which we save in the setup_efi_pci*
functions from arch/x86/boot/compressed/eboot.c, the EFI code / ROM itself
sometimes may contain data which is useful/necessary for peripheral drivers
to have access to.

Specifically the EFI code may contain an embedded copy of firmware which
needs to be (re)loaded into the peripheral. Normally such firmware would be
part of linux-firmware, but in some cases this is not feasible, for 2
reasons:

1) The firmware is customized for a specific use-case of the chipset / use
with a specific hardware model, so we cannot have a single firmware file
for the chipset. E.g. touchscreen controller firmwares are compiled
specifically for the hardware model they are used with, as they are
calibrated for a specific model digitizer.

2) Despite repeated attempts we have failed to get permission to
redistribute the firmware. This is especially a problem with customized
firmwares, these get created by the chip vendor for a specific ODM and the
copyright may partially belong with the ODM, so the chip vendor cannot
give a blanket permission to distribute these.

This commit adds support for finding peripheral firmware embedded in the
EFI code and making this available to peripheral drivers through the
standard firmware loading mechanism.

Note we check the EFI_BOOT_SERVICES_CODE for embedded firmware near the end
of start_kernel(), just before calling rest_init(), this is on purpose
because the typical EFI_BOOT_SERVICES_CODE memory-segment is too large for
early_memremap(), so the check must be done after mm_init(). This relies
on EFI_BOOT_SERVICES_CODE not being free-ed until efi_free_boot_services()
is called, which means that this will only work on x86 for now.

Reported-by: Dave Olsthoorn 
Suggested-by: Peter Jones 
Signed-off-by: Hans de Goede 
---
Changes in v2:
-Rebased on driver-core/driver-core-next
-Add documentation describing the EFI embedded firmware mechanism to:
 Documentation/driver-api/firmware/request_firmware.rst
-Add a new EFI_EMBEDDED_FIRMWARE Kconfig bool and only build the embedded
 fw support if this is set. This is an invisible option which should be
 selected by drivers which need this
-Remove the efi_embedded_fw_desc and dmi_system_id-s for known devices
 from the efi-embedded-fw code, instead drivers using this are expected to
 export a dmi_system_id array, with each entries' driver_data pointing to a
 efi_embedded_fw_desc struct and register this with the efi-embedded-fw code
-Use kmemdup to make a copy instead of efi_mem_reserve()-ing the firmware,
 this avoids us messing with the EFI memmap and avoids the need to make
 changes to efi_mem_desc_lookup()
-Make the firmware-loader code only fallback to efi_get_embedded_fw() if the
 passed in device has the "efi-embedded-firmware" device-property bool set
-Skip usermodehelper fallback when "efi-embedded-firmware" device-property
 is set

Changes in v3:
-Fix the docs using "efi-embedded-fw" as property name instead of
 "efi-embedded-firmware"
---
 .../driver-api/firmware/request_firmware.rst  |  70 +
 drivers/base/firmware_loader/main.c   |  33 
 drivers/firmware/efi/Kconfig  |   6 +
 drivers/firmware/efi/Makefile |   1 +
 drivers/firmware/efi/embedded-firmware.c  | 148 ++
 include/linux/efi.h   |   6 +
 include/linux/efi_embedded_fw.h   |  25 +++
 init/main.c   |   1 +
 8 files changed, 290 insertions(+)
 create mode 100644 drivers/firmware/efi/embedded-firmware.c
 create mode 100644 include/linux/efi_embedded_fw.h

diff --git a/Documentation/driver-api/firmware/request_firmware.rst 
b/Documentation/driver-api/firmware/request_firmware.rst
index 20f21ed427a5..189b02f815c9 100644
--- a/Documentation/driver-api/firmware/request_firmware.rst
+++ b/Documentation/driver-api/firmware/request_firmware.rst
@@ -68,3 +68,73 @@ If something went wrong request_firmware() returns non-zero 
and fw_entry
 is set to NULL. Once your driver is done with processing the firmware it
 can call call release_firmware(fw_entry) to release the firmware image
 and any related resource.
+
+EFI embedded firmware support
+=
+
+On some devices the system's EFI code / ROM may contain an embedded copy
+of firmware for some of the system's integrated peripheral devices and
+the peripheral's Linux device-driver needs to access this firmware.
+
+A device driver which needs this can describe the firmware it needs
+using an efi_embedded_fw_desc struct:
+
+.. kernel-doc:: include/linux/efi_embedded_fw.h
+   :functions: efi_embedded_fw_desc
+
+The EFI embedded-fw code works by scanning all EFI_BOOT_SERVICES_CODE memory
+segments for an eight byte sequence matching prefix, if the prefix is found it
+then does a crc32 over length bytes and if that matches makes a copy of length
+bytes and adds that to its list with found firmwares.
+
+To avoid doing this