Re: [PATCH] coredump - as root not only if euid switched

From: Peter Wächtler
Date: Fri Apr 23 2004 - 14:13:28 EST

Am Fr, 2004-04-23 um 17.35 schrieb Albert Cahalan:
> > While it's more secure to not dump core at all if the
> > program has switched euid, it's also very unpractical.
> > Since only programs started from root, being setuid
> > root or have CAP_SETUID it's far more practical to
> > dump as root.root mode 600. This is the bahavior
> > of Solaris.
> Solaris can keep their security holes.

I checked (older) versions on

HP-UX, True64, AiX, MacOsX

HP-UX didn't dump core on a seteuid 0->n prog
Aix,MacOsX and True64 dumped core with ownership of user
I could check Irix

> Consider a setuid core dump on removable media which
> is user-controlled.

boot into rescue system...

> Also consider filesystems that don't store full security
> data, like vfat and smb/cifs.
> Core dumps to remote filesystems are a problem in
> general, because the server might not implement the
> type of security you expect it to implement.

mkdir /var/cores
chmod a+rwx,o+t /var/cores
echo /var/cores/%e.core.%p > /proc/sys/kernel/core_pattern

> Here's a better idea: add a sysctl for insecure core
> dumps. When set, dump all cores as root.root mode 444.
> Ignore directory permissions when doing so, so that
> forcing dumps into a MacOS-style /cores directory does
> not require that users be able to access it normally.
> This lets appropriately authorized users debug setuid
> apps and get support for them without adding security
> holes like Solaris has.

It's tunable via coreadm

troll, troll

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