On Monday 18 June 2018 03:52 PM, Pekka Paalanen wrote:
On Mon, 18 Jun 2018 14:32:32 +0530
Ramalingam C <ramalinga...@intel.com> wrote:
On Monday 18 June 2018 02:23 PM, Pekka Paalanen wrote:
On Mon, 18 Jun 2018 13:38:09 +0530
Ramalingam C <ramalinga...@intel.com> wrote:
On Monday 18 June 2018 01:34 PM, Pekka Paalanen wrote:
On Sat, 16 Jun 2018 12:50:52 +0530
Ramalingam C <ramalinga...@intel.com> wrote:
The SRM table smells very much like compositor configuration,
especially because a) it is global state: you cannot program two
different tables to the same connector, and b) the compositor is
required to save it and use it later for all clients(?). One can also
envision a security issue, if a system allows third party apps: an app
could install a fake SRM table with a fake date.
Compositor is expected to store the latest SRM in the non-volatile and
update with only newest versions.
And it will supply the latest version to kernel(irrespective of what
version is provided by app). This caching is not per connector.
SRM table itself provides the version of it. and The validity of an SRM
is established by verifying the integrity of its
signature with the Digital Content Protection LLC public key, which is
specified by the Digital
Content Protection LLC. So no fake SRM will be accepted.
Right, so I would propose to make that completely separate.
Ok. So how that should be implemented? As another protocol extension?
I don't know. Is there a reason to do it by Wayland?
Yes. As we need to supply the SRM table through drm connector properties
to each ports HDCP authentication.
At the least we need to receive the signature validated latest SRM from
client and program into drm connector property.
Means storing SRM could be kept within the wayland client but only
drm_master can set the blob for the connectors.
And AFAIK signature verification also a crypto calculation with DCP LLC
public Key.
Thanks
Ram
Requesting content protection is a good fit to do by Wayland, because
it is per-window. Uploading a new SRB table is not tied to any window
or even a Wayland client, so why should it be a Wayland extension?
Is maintaining the SRB table the compositor's job, or is it a separate
service in the system that the compositor contacts?
I think this digs into the system design, and there is no obvious
benefit from using Wayland for it, that I don't think I can make a
recommendation.
For instance, if installing a new SRB table optionally uses internet
access to e.g. verify the signing key is still valid, then I don't
think it should be the compositor in charge of maintaining the SRB
table.
Thanks,
pq
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