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Date: Tue, 18 Apr 2023 00:53:30 +0200
From: Steffen Nurpmeso <steffen@...oden.eu>
To: oss-security@...ts.openwall.com
Subject: Re: CVE-2023-2002: Linux Bluetooth:
Unauthorized management command execution
Jakub Wilk wrote in
<20230417064047.dhrrkuzjmtx4yhgj@...lk.net>:
|* Steffen Nurpmeso <steffen@...oden.eu>, 2023-04-16 22:57:
|>have you verified that they do not use isatty(3)
|
|I'm pretty sure they do. But isatty(3) is implemented using the TCGETS
|ioctl, so that doesn't help.
Well everbody knows how this is implemented, most of the time.
There never was any systemcall that comes otherwise near of doing
that (except maybe fcntl). Plan9, maybe.
By the way out of interest and because of ringing in my ear for
one target i implemented sandboxing for an iteration of a very
simple non-front-line server to be released tomorrow,
pledge/unveil, seccomp(2) (glibc and musl), and capsicum(4) on
FreeBSD. seccomp(2) i find so expensive (i'd wish there would be
a first-level bitset or so), and very hard to do (argument
checking rather constant-only, of course: one could dynamically
build the filter, even use a library that aids in doing so, but
still), that i though the enormous capabilities of Linux regarding
"ip netns", "unshare" and "capsh", in conjunction with overlayfs,
ie containment, and keeping the server lean, seems more appealing.
All the libraries one has to use today, mostly evolving targets,
and blockboxes from my application's point of view. Yes,
i wondered how to create a bigger one i have on my TODO list,
which requires DNS lookups (and that potentially leads to the
black hole of TLS, HTTP, HTTP/2, QUIC). How to write this
securely with containment as above?
The musl client of the simple even needs a SYS_ioctl clearance for
normal writing to stdout (__stdout_write()).
Ciao!
(P.S.: it is great that QUIC will come "for free" with OpenSSL!)
--steffen
|
|Der Kragenbaer, The moon bear,
|der holt sich munter he cheerfully and one by one
|einen nach dem anderen runter wa.ks himself off
|(By Robert Gernhardt)
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