On Thu, Nov 30, 2017 at 6:18 AM, Frank Rowand <[email protected]> wrote:
> On 11/29/17 08:31, Rob Herring wrote:
>> On Wed, Nov 29, 2017 at 3:20 AM, Frank Rowand <[email protected]> wrote:
>>> On 11/27/17 15:58, Alan Tull wrote:
>>>> Here's a proposal for a whitelist to lock down the dynamic device tree.
>>>>
>>>> For an overlay to be accepted, all of its targets are required to be
>>>> on a target node whitelist.
>>>>
>>>> Currently the only way I have to get on the whitelist is calling a
>>>> function to add a node. That works for fpga regions, but I think
>>>> other uses will need a way of having adding specific nodes from the
>>>> base device tree, such as by adding a property like 'allow-overlay;'
>>>> or 'allow-overlay = "okay";' If that is acceptable, I could use some
>>>> advice on where that particular code should go.
>>>>
>>>> Alan
>>>>
>>>> Alan Tull (2):
>>>> of: overlay: add whitelist
>>>> fpga: of region: add of-fpga-region to whitelist
>>>>
>>>> drivers/fpga/of-fpga-region.c | 9 ++++++
>>>> drivers/of/overlay.c | 73 +++++++++++++++++++++++++++++++++++++++++++
>>>> include/linux/of.h | 12 +++++++
>>>> 3 files changed, 94 insertions(+)
>>>>
>>>
>>> The plan was to use connectors to restrict where an overlay could be applied.
>>> I would prefer not to have multiple methods for accomplishing the same thing
>>> unless there is a compelling reason to do so.
>>
>> Connector nodes need a mechanism to enable themselves, too. I don't
>> think connector nodes are going to solve every usecase.
>>
>> Rob
>>
>
> The overlay code related to connectors does not exist yet, so my comment
> is going to be theoretical.
>
> I would expect the overlay code to check that the target of the overlay
> fragment is a connector node, so there is no need to explicitly "enable"
> applying an overlay to a connector node.
This will depend on how connectors are implemented. My proposal in v1
is that device nodes can have a flag bit. If its not set, then an
overlay that contains fragments that target that node can't be
applied. There's probably other ways a connector node could be marked
as different from other nodes, but a flag bit seems simple. The
advantage to this scheme is that it gives me something I can use while
connectors don't exist yet and it will still will be useful later for
the implementation of connectors (giving connector drivers a way of
marking their device nodes as valid targets).
>
> -Frank
On 12/05/17 11:55, Alan Tull wrote:
> On Thu, Nov 30, 2017 at 6:18 AM, Frank Rowand <[email protected]> wrote:
>> On 11/29/17 08:31, Rob Herring wrote:
>>> On Wed, Nov 29, 2017 at 3:20 AM, Frank Rowand <[email protected]> wrote:
>>>> On 11/27/17 15:58, Alan Tull wrote:
>>>>> Here's a proposal for a whitelist to lock down the dynamic device tree.
>>>>>
>>>>> For an overlay to be accepted, all of its targets are required to be
>>>>> on a target node whitelist.
>>>>>
>>>>> Currently the only way I have to get on the whitelist is calling a
>>>>> function to add a node. That works for fpga regions, but I think
>>>>> other uses will need a way of having adding specific nodes from the
>>>>> base device tree, such as by adding a property like 'allow-overlay;'
>>>>> or 'allow-overlay = "okay";' If that is acceptable, I could use some
>>>>> advice on where that particular code should go.
>>>>>
>>>>> Alan
>>>>>
>>>>> Alan Tull (2):
>>>>> of: overlay: add whitelist
>>>>> fpga: of region: add of-fpga-region to whitelist
>>>>>
>>>>> drivers/fpga/of-fpga-region.c | 9 ++++++
>>>>> drivers/of/overlay.c | 73 +++++++++++++++++++++++++++++++++++++++++++
>>>>> include/linux/of.h | 12 +++++++
>>>>> 3 files changed, 94 insertions(+)
>>>>>
>>>>
>>>> The plan was to use connectors to restrict where an overlay could be applied.
>>>> I would prefer not to have multiple methods for accomplishing the same thing
>>>> unless there is a compelling reason to do so.
>>>
>>> Connector nodes need a mechanism to enable themselves, too. I don't
>>> think connector nodes are going to solve every usecase.
>>>
>>> Rob
>>>
>>
>> The overlay code related to connectors does not exist yet, so my comment
>> is going to be theoretical.
>>
>> I would expect the overlay code to check that the target of the overlay
>> fragment is a connector node, so there is no need to explicitly "enable"
>> applying an overlay to a connector node.
>
> This will depend on how connectors are implemented. My proposal in v1
> is that device nodes can have a flag bit. If its not set, then an
> overlay that contains fragments that target that node can't be
> applied. There's probably other ways a connector node could be marked
> as different from other nodes, but a flag bit seems simple. The
> advantage to this scheme is that it gives me something I can use while
> connectors don't exist yet and it will still will be useful later for
> the implementation of connectors (giving connector drivers a way of
> marking their device nodes as valid targets).
I think it is premature to add this code to the kernel when we don't
have an agreed upon architecture for what we are trying to achieve.
>
>>
>> -Frank
>