Date: Wed, 29 Nov 2017 13:46:12 +0000 From: Alan Cox <gnomes@...rguk.ukuu.org.uk> To: Kees Cook <keescook@...omium.org> Cc: "Luis R. Rodriguez" <mcgrof@...nel.org>, Djalal Harouni <tixxdz@...il.com>, Andy Lutomirski <luto@...nel.org>, Andrew Morton <akpm@...ux-foundation.org>, James Morris <james.l.morris@...cle.com>, Ben Hutchings <ben.hutchings@...ethink.co.uk>, Solar Designer <solar@...nwall.com>, Serge Hallyn <serge@...lyn.com>, Jessica Yu <jeyu@...nel.org>, Rusty Russell <rusty@...tcorp.com.au>, LKML <linux-kernel@...r.kernel.org>, linux-security-module <linux-security-module@...r.kernel.org>, kernel-hardening@...ts.openwall.com, Jonathan Corbet <corbet@....net>, Ingo Molnar <mingo@...nel.org>, "David S. Miller" <davem@...emloft.net>, Network Development <netdev@...r.kernel.org>, Peter Zijlstra <peterz@...radead.org>, Linus Torvalds <torvalds@...ux-foundation.org> Subject: Re: [PATCH v5 next 1/5] modules:capabilities: add request_module_cap() On Tue, 28 Nov 2017 13:39:58 -0800 Kees Cook <keescook@...omium.org> wrote: > On Tue, Nov 28, 2017 at 1:16 PM, Luis R. Rodriguez <mcgrof@...nel.org> wrote: > > And *all* auto-loading uses aliases? What's the difference between auto-loading > > and direct-loading? > > The difference is the process privileges. Unprivilged autoloading > (e.g. int n_hdlc = N_HDLC; ioctl(fd, > TIOCSETD, &n_hdlc)), triggers a privileged call to finit_module() > under CAP_SYS_MODULE. If you have CAP_SYS_DAC you can rename any module to ppp.ko and ask the network manager (which has the right permissions) to init a ppp connection. Capabilities alone are simply not enough to do any kind of useful protection on a current system and the Linux capability model is broken architecturally and not fixable because fixing it would break lots of real systems. I really don't care what the module loading rules end up with and whether we add CAP_SYS_YET_ANOTHER_MEANINGLESS_FLAG but what is actually needed is to properly incorporate it into securiy ruiles for whatever LSM you are using. Alan
Powered by blists - more mailing lists
Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.