Re: [RFC 0/8] Additional kmsg devices

Andy Lutomirski
2015-07-03T16:58:20Z

On Fri, Jul 3, 2015 at 8:09 AM, Marcin Niesluchowski
<m.niesluchow@samsung.com> 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