Re: Changing uid of another process?

bofh@diegeekdie.com
Mon, 13 Jul 1998 08:13:24 +0200


On Sat, Jul 11, 1998 at 05:59:33AM +0200, Rik van Riel wrote:
>
> Passing credentials by means of a Unix domain socket would
> open up such an awful lot of security holes that we'd be
> better of having just PID identification :)

Please tell us about them.

I've been thinking about this and I really can't find out how that is
supposed to happen. In order to recieve a filedescriptor you have to tell
recvmsg that you want to recieve one. In order to recieve the credentials
you would have to say that you want to recieve them. No existing program
does say so today so they wouldn't be affected.

There are two ways of abusing a program that wants to recieve credentials:
1) If all uids are allowed to send credentials then a program may perhapps
connect to the wrong server and that server sends its uid. That in turn
would make it possible for that uid to look through the servers memory
which may be bad for some applications.

2) If only root (or programs with the right capability) is allowed to send
credentials then a program could get the wrong uid. But then again,
if someone got hold of your root account you usualy don't have much
protection.

/Sebastian

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