Re: getpeereid() for Linux

[Michael Bacarella <mbac@nyct.net>]

> Would anyone like to give me a helping hand in implementing the
> getpeereid() syscall for Linux?  See the following page for the
> documentation of the OpenBSD implementation:
> 
> http://www.openbsd.org/cgi-bin/man.cgi?query=getpeereid&sektion=2&apropos=0&manpath=OpenBSD+Current
> 
> I think I could work out the kernel data structures to gather the
> relevant data from, however, I won't get all the locking stuff right.
>
> OTOH, is there any chance that the addition of such a syscall would be
> accepted?

There's no need. The equivalent functionality can already be
implemented in userspace.

------

#include <sys/socket.h>

uid_t getpeereuid(int sd)
{
	struct ucred cred;
	int len = sizeof (cred);

	if (getsockopt(sd,SOL_SOCKET,SO_PEERCRED,&cred,&len))
		return -1;

	return cred.uid;
}

------

The same can be done for gid, and even pid.

Yes, Linux rules.

-- 
Michael Bacarella <mbac@nyct.net>
Technical Staff / System Development,
New York Connect.Net, Ltd.