perfetto: allow producers to supply shared memory
This concerns the data transfer between an untrusted producer process,
and the tracing service (traced daemon). They communicate over a
combination of a unix socket and shared memory.
Normally, the service creates the shared memory region, and hands it off
to the producer process (see perfetto_producer() macro). This patch
allows for an alternative scheme, where the producer process is allowed
to create the shared memory region, which will then be adopted by the
tracing service. The service already inherently doesn't trust the
producer, so it'll validate that the shared memory is appropriately
sealed before using it.
The immediate use-case is chrome's go/perfetto-startup-tracing-v2. But
this mode has advantages (e.g. being able to write to the shared memory
before connecting) for other producer domains as well.
Bug: 148841422
Change-Id: I90f864b900958792553f0208f4a0041dbf2892cc
3 files changed