Re: OpenBSD Security Advisory: BSD I/O Signals

[alan () LXORGUK UKUU ORG UK (Alan Cox)]

> systems, including BSDI, NetBSD, OpenBSD, and FreeBSD, in their most
> recent release revisions. Additionally, this problem is known to affect
> SGI IRIX, and may affect other operating systems as well.

The recycling the PID version of the bug is present in Linux. We fixed the
other version of it last time this lot came up on security lists (2 ? 3 years
ago).

> interface to I/O notification must be modified to check credentials when
> the TIOCSPGRP (or equivalent) ioctl() is used to set notificatio PID; the
> OpenBSD patch resolves all currently known occurances of this in that

I don't believe the fix is correct in a "not changing behaviour" way. It
does seem right in a security way. Assigning version stamps (eg a timestamp)
to processes on creation time and using that as an authentication key would
be as simple and preserve the existing setup which allows suid programs
to set up signal delivery to another and drop priviledges.

Alan