Re: [libdc] Broadcast write requests desired in the kernel interface?

[Stefan R. <st...@s5...>]

Damien Douxchamps wrote:
> OK, so if eth and sbp2 are "safe" by not using bcast, then what else
> could use it besides libdc1394? dv1394?

There is not much harm that can be done by talking to DV devices, or 
AV/C devices in general.  Their character device file permissions would 
usually be set rather lax, e.g. writable by a video group to which 
normal users belong to.

I don't know AV/C well enough; the question is whether devices accept 
broadcast write requests to the FCP_COMMAND register.  If yes, a program 
could for example start video streaming or things like that.  The 
program would then have to have write permission on at least one 
arbitrary device file for a node on the same bus to use that one for 
reception or transmission of a video or audio stream.

However, I find it unlikely that any FireWire device file will get 
looser permissions than a device file for an AV/C device.

A general issue is whether devices accept broadcast write requests into 
CSR architecture core registers, notably RESET_START.  I should test 
this with the various SBP-2 devices I got.
-- 
Stefan Richter
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http://arcgraph.de/sr/