[PATCH v6 0/3] ALSA: pcm: anonymous dup implementation

[PATCH v6 0/3] ALSA: pcm: anonymous dup implementation

[Jaroslav Kysela]

This patchset contains the anonymous dup implementation with permissions
checking for the ALSA's PCM interface in kernel to enable the restricted
DMA sound buffer sharing for the restricted tasks.

The code was tested through qemu and it seems to be pretty stable.

The initial tinyalsa implementation can be found here:

  https://github.com/perexg/tinyalsa/commits/anondup

The filtering might be refined. It depends on the real requirements.
Perhaps, we may create more ioctl groups. Any comments are more than
welcome.

v2 of the patches:

- change clone parameter to subdevice number for the pcm attach
- change SNDRV_PCM_PERM_MAX to SNDRV_PCM_PERM_MASK
- the tinyalsa implementation was a little updated (restructured)

v3 of the patches:

- group integer declarations in snd_pcm_anonymous_dup()
- replaced substream->pcm with pcm in snd_pcm_anonymous_dup()
- added SNDRV_PCM_PERM_RW check for read/write/readv/writev syscalls

v4 of the patches:

- more simple restriction control (only two modes - full/buffer)
- the tinyalsa implementation follows this change

v5 of the patches:

- merge pcm_..._mmap_allowed fcns to the snd_pcm_mmap_... fcns

v6:

- add proper open_mutex protection for snd_pcm_open_file()

Cc: Phil Burk <philburk@google.com>
Cc: Zach Riggle <riggle@google.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Baolin Wang <baolin.wang@linaro.org>

Jaroslav Kysela (3):
  ALSA: pcm: implement the anonymous dup (inode file descriptor)
  ALSA: pcm: merge pcm_..._mmap_allowed fcns to the snd_pcm_mmap_...
    fcns
  ALSA: pcm: implement the mmap buffer mode for the anonymous dup

 include/sound/pcm.h         |  10 +--
 include/uapi/sound/asound.h |   6 +-
 sound/core/oss/pcm_oss.c    |   2 +-
 sound/core/pcm.c            |  13 ++--
 sound/core/pcm_compat.c     |   1 +
 sound/core/pcm_native.c     | 154 +++++++++++++++++++++++++++++++++-----------
 6 files changed, 133 insertions(+), 53 deletions(-)

-- 
2.13.6

Re: [PATCH v6 0/3] ALSA: pcm: anonymous dup implementation

[Ricardo Biehl Pasquali]

What about file sealing?

See:

Jonathan Corbet's article about sealed files (2014-04-09).
<https://lwn.net/Articles/593918/>.

Theodore Ts'o reply to file sealing patch suggesting an
implementation on VFS (2014-03-20).
Re: [PATCH 0/6] File Sealing & memfd_create()
<https://lwn.net/Articles/593963/>.

	pasquali

Re: [PATCH v6 0/3] ALSA: pcm: anonymous dup implementation

[Mark Brown]

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On Mon, Feb 04, 2019 at 07:38:14PM +0100, Jaroslav Kysela wrote:
> This patchset contains the anonymous dup implementation with permissions
> checking for the ALSA's PCM interface in kernel to enable the restricted
> DMA sound buffer sharing for the restricted tasks.

Reviewed-by: Mark Brown <broonie@kernel.org>

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Re: [PATCH v6 0/3] ALSA: pcm: anonymous dup implementation

[Takashi Iwai]

On Mon, 04 Feb 2019 19:38:14 +0100,
Jaroslav Kysela wrote:
> 
> This patchset contains the anonymous dup implementation with permissions
> checking for the ALSA's PCM interface in kernel to enable the restricted
> DMA sound buffer sharing for the restricted tasks.
> 
> The code was tested through qemu and it seems to be pretty stable.
> 
> The initial tinyalsa implementation can be found here:
> 
>   https://github.com/perexg/tinyalsa/commits/anondup
> 
> The filtering might be refined. It depends on the real requirements.
> Perhaps, we may create more ioctl groups. Any comments are more than
> welcome.

Is this patchset targeted for 5.1 merge?

I hesitate to merge it for now, as the new API hasn't been tested much
yet...  If it's for 5.1, we need test coverage and more reviews
quickly.


thanks,

Takashi

> 
> v2 of the patches:
> 
> - change clone parameter to subdevice number for the pcm attach
> - change SNDRV_PCM_PERM_MAX to SNDRV_PCM_PERM_MASK
> - the tinyalsa implementation was a little updated (restructured)
> 
> v3 of the patches:
> 
> - group integer declarations in snd_pcm_anonymous_dup()
> - replaced substream->pcm with pcm in snd_pcm_anonymous_dup()
> - added SNDRV_PCM_PERM_RW check for read/write/readv/writev syscalls
> 
> v4 of the patches:
> 
> - more simple restriction control (only two modes - full/buffer)
> - the tinyalsa implementation follows this change
> 
> v5 of the patches:
> 
> - merge pcm_..._mmap_allowed fcns to the snd_pcm_mmap_... fcns
> 
> v6:
> 
> - add proper open_mutex protection for snd_pcm_open_file()
> 
> Cc: Phil Burk <philburk@google.com>
> Cc: Zach Riggle <riggle@google.com>
> Cc: Mark Brown <broonie@kernel.org>
> Cc: Leo Yan <leo.yan@linaro.org>
> Cc: Baolin Wang <baolin.wang@linaro.org>
> 
> Jaroslav Kysela (3):
>   ALSA: pcm: implement the anonymous dup (inode file descriptor)
>   ALSA: pcm: merge pcm_..._mmap_allowed fcns to the snd_pcm_mmap_...
>     fcns
>   ALSA: pcm: implement the mmap buffer mode for the anonymous dup
> 
>  include/sound/pcm.h         |  10 +--
>  include/uapi/sound/asound.h |   6 +-
>  sound/core/oss/pcm_oss.c    |   2 +-
>  sound/core/pcm.c            |  13 ++--
>  sound/core/pcm_compat.c     |   1 +
>  sound/core/pcm_native.c     | 154 +++++++++++++++++++++++++++++++++-----------
>  6 files changed, 133 insertions(+), 53 deletions(-)
> 
> -- 
> 2.13.6
>