Re: Signal handling different for root and others

From: Andi Kleen (ak@suse.de)
Date: Mon Sep 11 2000 - 19:33:27 EST


On Tue, Sep 12, 2000 at 02:20:02AM +0200, jury gerold wrote:
> I ran into a problem with 2.2.x kernels, posix signals and sockets.
>
> I have a program that creates a serversocket, puts it into listen state,
> attaches the socket to a realtime signal and simply waits for the signal.
>
> When i create a connection (telnet a.b.c.d port) the signal is delivered depending
> on the user that does the telnet.
> If root creates the socket, then only root or another machine is able to trigger the signal
> by connecting to the socket.
> Normal users are only able to create a SIGIO signal when connecting.

That's very unlikely. TCP does not propagate gid/uid information over sockets,
not even over localhost.
There was probably some other factor during your tests. When you overflow
the rt signal queue then the kernel will fall back to sending SIGIO. In
this case you have to collect outstanding events using poll.

-Andi
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