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[PATCH v5 0/3] RFC: Secure Memory Allocation Framework

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  [PATCH v5 0/3] RFC: Secure Memory Allocation Framework Benjamin Gaignard <benjamin.gaignard@linaro.org> - 2015-10-21 11:30 +0200
    Re: [PATCH v5 0/3] RFC: Secure Memory Allocation Framework James Morris <jmorris@namei.org> - 2015-10-21 16:40 +0200
      Re: [PATCH v5 0/3] RFC: Secure Memory Allocation Framework Benjamin Gaignard <benjamin.gaignard@linaro.org> - 2015-10-21 18:00 +0200

#1252618 — [PATCH v5 0/3] RFC: Secure Memory Allocation Framework

version 5 changes:
 - rebased on kernel 4.3-rc6
 - rework locking schema and make handle status use an atomic_t
 - add a fake secure module to allow performing tests without trusted
   environment

version 4 changes:
 - rebased on kernel 4.3-rc3
 - fix missing EXPORT_SYMBOL for smaf_create_handle()

version 3 changes:
 - Remove ioctl for allocator selection instead provide the name of
   the targeted allocator with allocation request.
   Selecting allocator from userland isn't the prefered way of working
   but is needed when the first user of the buffer is a software component.
 - Fix issues in case of error while creating smaf handle.
 - Fix module license.
 - Update libsmaf and tests to care of the SMAF API evolution
   https://git.linaro.org/people/benjamin.gaignard/libsmaf.git

version 2 changes:
 - Add one ioctl to allow allocator selection from userspace.
   This is required for the uses case where the first user of
   the buffer is a software IP which can't perform dma_buf attachement.
 - Add name and ranking to allocator structure to be able to sort them.
 - Create a tiny library to test SMAF:
   https://git.linaro.org/people/benjamin.gaignard/libsmaf.git
 - Fix one issue when try to secure buffer without secure module registered

The outcome of the previous RFC about how do secure data path was the need
of a secure memory allocator (https://lkml.org/lkml/2015/5/5/551)

SMAF goal is to provide a framework that allow allocating and securing
memory by using dma_buf. Each platform have it own way to perform those two
features so SMAF design allow to register helper modules to perform them.

To be sure to select the best allocation method for devices SMAF implement
deferred allocation mechanism: memory allocation is only done when the first
device effectively required it.
Allocator modules have to implement a match() to let SMAF know if they are
compatibles with devices needs.
This patch set provide an example of allocator module which use
dma_{alloc/free/mmap}_attrs() and check if at least one device have
coherent_dma_mask set to DMA_BIT_MASK(32) in match function. 
I have named smaf-cma.c like it is done for drm_gem_cma_helper.c even if 
a better name could be found for this file.

Secure modules are responsibles of granting and revoking devices access rights
on the memory. Secure module is also called to check if CPU map memory into
kernel and user address spaces.
An example of secure module implementation can be found here:
http://git.linaro.org/people/benjamin.gaignard/optee-sdp.git
This code isn't yet part of the patch set because it depends on generic TEE
which is still under discussion (https://lwn.net/Articles/644646/)

For allocation part of SMAF code I get inspirated by Sumit Semwal work about
constraint aware allocator.


Benjamin Gaignard (3):
  create SMAF module
  SMAF: add CMA allocator
  SMAF: add fake secure module

 drivers/Kconfig                |   2 +
 drivers/Makefile               |   1 +
 drivers/smaf/Kconfig           |  17 +
 drivers/smaf/Makefile          |   3 +
 drivers/smaf/smaf-cma.c        | 200 +++++++++++
 drivers/smaf/smaf-core.c       | 753 +++++++++++++++++++++++++++++++++++++++++
 drivers/smaf/smaf-fakesecure.c |  92 +++++
 include/linux/smaf-allocator.h |  54 +++
 include/linux/smaf-secure.h    |  75 ++++
 include/uapi/linux/smaf.h      |  52 +++
 10 files changed, 1249 insertions(+)
 create mode 100644 drivers/smaf/Kconfig
 create mode 100644 drivers/smaf/Makefile
 create mode 100644 drivers/smaf/smaf-cma.c
 create mode 100644 drivers/smaf/smaf-core.c
 create mode 100644 drivers/smaf/smaf-fakesecure.c
 create mode 100644 include/linux/smaf-allocator.h
 create mode 100644 include/linux/smaf-secure.h
 create mode 100644 include/uapi/linux/smaf.h

-- 
1.9.1

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#1252882

On Wed, 21 Oct 2015, Benjamin Gaignard wrote:

> 
> The outcome of the previous RFC about how do secure data path was the need
> of a secure memory allocator (https://lkml.org/lkml/2015/5/5/551)
> 

Have you addressed all the questions raised by Alan here:

https://lkml.org/lkml/2015/5/8/629

Also, is there any application of this beyond DRM?


- James
-- 
James Morris
<jmorris@namei.org>

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#1252984

2015-10-21 16:34 GMT+02:00 James Morris <jmorris@namei.org>:
> On Wed, 21 Oct 2015, Benjamin Gaignard wrote:
>
>>
>> The outcome of the previous RFC about how do secure data path was the need
>> of a secure memory allocator (https://lkml.org/lkml/2015/5/5/551)
>>
>
> Have you addressed all the questions raised by Alan here:
>
> https://lkml.org/lkml/2015/5/8/629

SMAF create /dev/smaf where all allocations could be done and is the
owner of the dmabuf.
Secure module is called to check permissions before that the CPU could
access to the memory.

I hope this cover what Alan expected but I can't speak form him.

>
> Also, is there any application of this beyond DRM?
>

If you don't use the secure part you can consider that SMAF is a
central allocator with helpers to select
the best allocator for your hardware devices.
While SMAF doesn't rely on DRM concepts (crypto, CENC, keys etc...) we
can use it outside this context but obviously it that been first
designed for DRM uses cases.

>
> - James
> --
> James Morris
> <jmorris@namei.org>
>



-- 
Benjamin Gaignard

Graphic Working Group

Linaro.org │ Open source software for ARM SoCs

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