Replace uid==0 tests with capability checks

[Corinna Vinschen]

On Mar 19 02:08, Peter Stuge wrote:
> Corinna Vinschen wrote:
> > Is there any chance this can be discussed at one point?
> 
> I approve too, even though I am not really affected.
> 
> Maybe it could take advantage of capabilities in Linux though.

That's the idea.  I'm not asking for Cygwin's benefit alone.  A couple
of OSes have finer grained capabilities.  And, as far as I'm concerned,
code like this:

  if (uid_has_capability(getuid(), CAP_SWITCH_USER))

is much more instructive than

  if (getuid() == 0)

Likewise, this:

  if (channel_input_port_forward_request(
      uid_has_capability(s->pw->pw_uid, CAP_RSVD_PORTS),
      options.gateway_ports) < 0) {

is more instructive than this:

  if (channel_input_port_forward_request(s->pw->pw_uid == 0,
      options.gateway_ports) < 0) { 

So, in my eyes this change would make the code clearer even in the
upstream OpenBSD-only code.  Given that the uid_has_capability function
would be a no-brainer on BSD and other systems having no capabilities
model

  int
  uid_has_capability (uid_t uid, int capability __attribute ((unused)))
  {
    return uid == 0;
  }

I only see advantages here.


Corinna

-- 
Corinna Vinschen
Cygwin Project Co-Leader
Red Hat