Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932946AbbKERsa (ORCPT ); Thu, 5 Nov 2015 12:48:30 -0500 Received: from tschil.ethgen.ch ([5.9.7.51]:46699 "EHLO tschil.ethgen.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932525AbbKERs3 (ORCPT ); Thu, 5 Nov 2015 12:48:29 -0500 Date: Thu, 5 Nov 2015 18:48:24 +0100 From: Klaus Ethgen To: "Serge E. Hallyn" Cc: Andy Lutomirski , Linus Torvalds , Richard Weinberger , LKML , Christoph Lameter , Andy Lutomirski , Serge Hallyn , Kees Cook , Andrew Morton Subject: Re: [KERNEL] Re: [KERNEL] Re: [KERNEL] Re: [KERNEL] Re: Kernel 4.3 breaks security in systems using capabilities Message-ID: <20151105174823.GD9307@ikki.ethgen.ch> References: <20151102191616.GA2158@ikki.ethgen.ch> <20151105101953.GA15293@ikki.ethgen.ch> <20151105161512.GA2180@mail.hallyn.com> <20151105171701.GB9307@ikki.ethgen.ch> <20151105173438.GA3378@mail.hallyn.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1; x-action=pgp-signed In-Reply-To: <20151105173438.GA3378@mail.hallyn.com> OpenPGP: id=79D0B06F4E20AF1C; url=http://www.ethgen.ch/~klaus/79D0B06F4E20AF1C.txt; preference=signencrypt User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2554 Lines: 57 -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 Am Do den 5. Nov 2015 um 18:34 schrieb Serge E. Hallyn: > > Am Do den 5. Nov 2015 um 17:15 schrieb Serge E. Hallyn: > > > I think if you follow your idea to its logical conclusions, you end > > > up wanting set SECURE_ALL_BITS | SECURE_ALL_LOCKS, which will include > > > SECURE_NO_CAP_AMBIENT_RAISE, disabling ambient capabilities. > > > > That I did miss out and seems to be the solution for the problem. So > > adding cap_secure_all_bits,cap_secure_all_locks=ep to every binary that > > gets other caps should solve it? > > No that doesn't work, you have to use prctl to set those bits. If you > can get your system to be fully rootless, you can have init or initramfs > do this for you. It'll mean that root and setuid-root binaries have no > automatic privileges beside owning host (proc/sys) files. So this is not helping much. But for me it is at least an idea to how to have abient capabilities _and_ full control for admin. It would be an un-capability but at least would allow the admin to change the behaviour. Another one, that would be much better would be something like cap_ambient_cap capability to explicitly allow the use of ambient capabilities. I have to say that I do not know much about prctl. Just reading the man page currently. But this seems to be about the second way of taking away rights from UID 0 instead of explicitly giving rights to selective binaries. Regards Klaus - -- Klaus Ethgen http://www.ethgen.ch/ pub 4096R/4E20AF1C 2011-05-16 Klaus Ethgen Fingerprint: 85D4 CA42 952C 949B 1753 62B3 79D0 B06F 4E20 AF1C -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQGcBAEBCgAGBQJWO5ZiAAoJEKZ8CrGAGfasxrYMALQUBljC4ZECnt8C+kjADz+p Myqlotr5LZ70+UdOGAnd6ldDyomFKoQZB+IHOm8NIqx+HH8IivLPUVHePyJt7Zlj t1fgjlYRlDx5Zourbw8eGW/diQF8FBPF+JKG08XHqh25DiLTijevgrC7TnavQuQm RQaYqnVyPCBaEMUqE4iIaJ7hz/GY6hPX/hQlBU5z26Z/0QLa/DNQwyP0RJWoGp2q rzCgU0K1pemtoik0HSEdm3li9rFicWBpJsz+5mSsJUx01q30zMzBCHan/IOaPseZ 476+OWY/AGWtA4qpcC4MLAqfC2atYkVZ2/xiEarRdl71SAepV3n4ZPInIsJZ1/3k mUs/EJ1pBMKkrcU9Nry9Hra+uMl77Gin8eG+5RE5B2IdeyKGEr1lCRVe4Dd27M0t H3hy6WhB4lFg/k2TWZK5Haz/6Nn2chSPntiOWnyw+vN7M1q6yiiIo82GI1Du0T0W vhwgISmEqtAa8CAaSZQuW6VpJ1Z9ztN5+qnhE6mzKg== =T9bn -----END PGP SIGNATURE----- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/