Re: [RFC 0/8] Additional kmsg devices

On Fri, Jul 3, 2015 at 8:09 AM, Marcin Niesluchowski
[off-list ref] wrote:

* Message credibility: Lets imagine simple service which collects logs via
unix sockets. There is no reliable way of identifying logging process.
getsockopt() with SO_PEERCRED option would give pid form cred structure, but
according to manual it may not be of actual logging process:
  "The returned credentials are those that were in effect at the time of the
call to connect(2) or socketpair(2)."
      - select(7)

There's SCM_CREDENTIALS, which is dangerous, but it's dangerous in
exactly the same way that your patches are dangerous.  You're
collecting PID/TID when write(2) is called, and it's very easy to get
another process to call write(2) on your behalf, because write(2)
isn't supposed to collect credentials.

--Andy