Message-ID: <CA+M3ks6BkGuwKMYZXHPBeawB-5m+O1HxZvPpfbjO6voyoVJyZg@mail.gmail.com>
Date:   Fri, 7 Oct 2016 15:54:41 +0200
From:   Benjamin Gaignard <benjamin.gaignard@...aro.org>
To:     Rob Clark <robdclark@...il.com>
Cc:     "linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        Cc Ma <cc.ma@...iatek.com>,
        Joakim Bech <joakim.bech@...aro.org>,
        Burt Lien <burt.lien@...aro.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Linaro MM SIG Mailman List <linaro-mm-sig@...ts.linaro.org>,
        Linaro Kernel Mailman List <linaro-kernel@...ts.linaro.org>
Subject: Re: [PATCH v10 0/3] Secure Memory Allocation Framework

Rob,

how do you know which devices are concerned when listing the constraints ?
Does combine_capabilities is done from each allocation or can it be cached ?

Regards,
Benjmain

2016-10-06 18:54 GMT+02:00 Rob Clark <robdclark@...il.com>:
> so there is discussion about a "central userspace allocator" (ie. more
> like a common userspace API that could be implemented on top of
> various devices/APIs) to decide in a generic way which device could
> allocate.
>
>   https://github.com/cubanismo/allocator
>
> and I wrote up some rough thoughts/proposal about how the usage might
> look.. just rough, so don't try to compile it or anything, and not
> consensus yet so it will probably change/evolve..
>
>   https://github.com/robclark/allocator/blob/master/USAGE.md
>
> I think ion could be just another device to share buffers with, which
> happens to not impose any specific constraints.  How "liballoc-ion.so"
> backend figures out how to map constraints/usage to a heap is a bit
> hand-wavey at the moment.
>
> BR,
> -R
>
> On Wed, Oct 5, 2016 at 9:40 AM, Benjamin Gaignard
> <benjamin.gaignard@...aro.org> wrote:
>> because with ion it is up to userland to decide which heap to use
>> and until now userland doesn't have any way to get device constraints...
>>
>> I will prefer let a central allocator (in kernel) decide from the
>> attached devices
>> which allocator is the best. It is what I have implemented in smaf.
>>
>> Benjamin
>>
>>
>> 2016-10-05 15:19 GMT+02:00 Daniel Vetter <daniel@...ll.ch>:
>>> On Tue, Oct 04, 2016 at 01:47:21PM +0200, Benjamin Gaignard wrote:
>>>> version 10 changes:
>>>>  - rebased on kernel 4.8 tag
>>>>  - minor typo fix
>>>>
>>>> version 9 changes:
>>>>  - rebased on 4.8-rc5
>>>>  - struct dma_attrs doesn't exist anymore so update CMA allocator
>>>>    to compile with new dma_*_attr functions
>>>>  - add example SMAF use case in cover letter
>>>>
>>>> version 8 changes:
>>>>  - rework of the structures used within ioctl
>>>>    by adding a version field and padding to be futur proof
>>>>  - rename fake secure moduel to test secure module
>>>>  - fix the various remarks done on the previous patcheset
>>>>
>>>> version 7 changes:
>>>>  - rebased on kernel 4.6-rc7
>>>>  - simplify secure module API
>>>>  - add vma ops to be able to detect mmap/munmap calls
>>>>  - add ioctl to get number and allocator names
>>>>  - update libsmaf with adding tests
>>>>    https://git.linaro.org/people/benjamin.gaignard/libsmaf.git
>>>>  - add debug log in fake secure module
>>>>
>>>> version 6 changes:
>>>>  - rebased on kernel 4.5-rc4
>>>>  - fix mmapping bug while requested allocation size isn't a a multiple of
>>>>    PAGE_SIZE (add a test for this in libsmaf)
>>>>
>>>> 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
>>>>
>>>> SMAF aim to solve two problems: allocating memory that fit with hardware IPs
>>>> constraints and secure those data from bus point of view.
>>>>
>>>> One example of SMAF usage is camera preview: on SoC you may use either an USB
>>>> webcam or the built-in camera interface and the frames could be send directly
>>>> to the dipslay Ip or handle by GPU.
>>>> Most of USB interfaces and GPU have mmu but almost all built-in camera
>>>> interace and display Ips don't have mmu so when selecting how allocate
>>>> buffer you need to be aware of each devices constraints (contiguous memroy,
>>>> stride, boundary, alignment ...).
>>>> ION has solve this problem by let userland decide which allocator (heap) to use
>>>> but this require to adapt userland for each platform and sometime for each
>>>> use case.
>>>>
>>>> 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.
>>>>
>>>> In the same camera preview use case, SMAF allow to protect the data from being
>>>> read by unauthorized IPs (i.e. a malware to dump camera stream).
>>>> Until now I have only see access rights protection at process/thread level
>>>> (PKeys/MPK) or on file (SELinux) but nothing allow to drive data bus firewalls.
>>>> SMAF propose an interface to control and implement those firewalls.
>>>> Like IOMMU, firewalls IPs can help to protect memory from malicious/faulty devices
>>>> that are attempting DMA attacks.
>>>>
>>>> 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.
>>>
>>> semi-random review comment, and a bit late: Why not implement smaf as a
>>> new heap in ion? I think consensus is pretty much that we'll be stuck with
>>> ion forever, and I think it's better to have 1 central buffer allocater
>>> than lots of them ...
>>> -Daniel
>>>
>>>>
>>>> Benjamin Gaignard (3):
>>>>   create SMAF module
>>>>   SMAF: add CMA allocator
>>>>   SMAF: add test secure module
>>>>
>>>>  drivers/Kconfig                |   2 +
>>>>  drivers/Makefile               |   1 +
>>>>  drivers/smaf/Kconfig           |  17 +
>>>>  drivers/smaf/Makefile          |   3 +
>>>>  drivers/smaf/smaf-cma.c        | 186 ++++++++++
>>>>  drivers/smaf/smaf-core.c       | 818 +++++++++++++++++++++++++++++++++++++++++
>>>>  drivers/smaf/smaf-testsecure.c |  90 +++++
>>>>  include/linux/smaf-allocator.h |  45 +++
>>>>  include/linux/smaf-secure.h    |  65 ++++
>>>>  include/uapi/linux/smaf.h      |  85 +++++
>>>>  10 files changed, 1312 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-testsecure.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
>>>>
>>>> _______________________________________________
>>>> dri-devel mailing list
>>>> dri-devel@...ts.freedesktop.org
>>>> https://lists.freedesktop.org/mailman/listinfo/dri-devel
>>>
>>> --
>>> Daniel Vetter
>>> Software Engineer, Intel Corporation
>>> http://blog.ffwll.ch
>>
>>
>>
>> --
>> Benjamin Gaignard
>>
>> Graphic Study Group
>>
>> Linaro.org │ Open source software for ARM SoCs
>>
>> Follow Linaro: Facebook | Twitter | Blog
>> _______________________________________________
>> dri-devel mailing list
>> dri-devel@...ts.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/dri-devel



-- 
Benjamin Gaignard

Graphic Study Group

Linaro.org │ Open source software for ARM SoCs

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