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From: Ben Hutchings <ben@decadent.org.uk>
To: Djalal Harouni <tixxdz@gmail.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Andy Lutomirski <luto@kernel.org>,
	Kees Cook <keescook@chromium.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	serge@hallyn.com, kernel-hardening@lists.openwall.com,
	linux-security-module@vger.kernel.org
Cc: Linux API <linux-api@vger.kernel.org>,
	Dongsu Park <dpark@posteo.net>,
	Casey Schaufler <casey@schaufler-ca.com>,
	James Morris <james.l.morris@oracle.com>,
	Paul Moore <paul@paul-moore.com>,
	Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jonathan Corbet <corbet@lwn.net>, Jessica Yu <jeyu@redhat.com>,
	Rusty Russell <rusty@rustcorp.com.au>,
	Arnaldo Carvalho de Melo <acme@redhat.com>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	Ingo Molnar <mingo@kernel.org>,
	zendyani@gmail.com, Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH v3 1/2] modules:capabilities: automatic module loading restriction
Date: Thu, 20 Apr 2017 03:22:22 +0100	[thread overview]
Message-ID: <1492654942.31767.21.camel@decadent.org.uk> (raw)
In-Reply-To: <1492640420-27345-2-git-send-email-tixxdz@gmail.com>

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On Thu, 2017-04-20 at 00:20 +0200, Djalal Harouni wrote:
[...] 
> +modules_autoload:
> +
> +A sysctl to control if modules auto-load feature is allowed or not.
> +This sysctl complements "modules_disabled" which is for all module
> +operations where this flag applies only to automatic module loading.
> +Automatic module loading happens when programs request a kernel feature
> +that is implemented by an unloaded module, the kernel automatically
> +runs the program pointed by "modprobe" sysctl in order to load the
> +corresponding module.
> +
> +When modules_autoload is set to (0), the default, there are no
> +restrictions.
> +
> +When modules_autoload is set to (1), processes must have CAP_SYS_MODULE
> +to be able to trigger a module auto-load operation, or CAP_NET_ADMIN
> +for modules with a 'netdev-%s' alias.
> +
> +When modules_autoload is set to (2), automatic module loading is
> +disabled for all. Once set, this value can not be changed.

I would expect a parameter 'modules_autoload' to be a boolean, so this
behaviour would be surprising.

What is the point of mode 2?  Why would someone want to set
modules_disabled=0 and modules_autoload=2?

[...]
> --- a/kernel/module.c
> +++ b/kernel/module.c
[...]
> +static int modules_autoload_privileged_access(const char *name)
> +{
> +	if (capable(CAP_SYS_MODULE))
> +		return 0;
> +	else if (name && strstr(name, "netdev-") && capable(CAP_NET_ADMIN))
[...]

We want a prefix match, so use strncmp() not strstr().

Ben.

-- 
Ben Hutchings
It is easier to change the specification to fit the program than vice
versa.


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  parent reply	other threads:[~2017-04-20  2:22 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-19 22:20 [PATCH v3 0/2] modules:capabilities: automatic module loading restrictions Djalal Harouni
2017-04-19 22:20 ` [PATCH v3 1/2] modules:capabilities: automatic module loading restriction Djalal Harouni
2017-04-19 23:16   ` Andy Lutomirski
2017-04-20  2:22   ` Ben Hutchings [this message]
2017-04-20 12:44     ` [kernel-hardening] " Djalal Harouni
2017-04-20 15:02       ` Ben Hutchings
     [not found]         ` <1492700543.31767.23.camel-/+tVBieCtBitmTQ+vhA3Yw@public.gmane.org>
2017-04-20 20:39           ` [kernel-hardening] " Djalal Harouni
     [not found]             ` <CAEiveUdFL53XyQpacmN6f8F28M0bLQDcetpRXJjrJ10vDmQi8Q-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-04-20 21:28               ` Kees Cook
2017-04-19 22:20 ` [PATCH v3 2/2] modules:capabilities: add a per-task modules autoload restriction Djalal Harouni
2017-04-19 23:15   ` Andy Lutomirski
2017-04-19 23:43     ` Kees Cook
2017-04-20  2:41       ` Andy Lutomirski
     [not found]         ` <CALCETrUueOx1tqj+Ru93KGpy2HHR-A_GQ6DrAppiomkPTtX7Lw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-04-21 23:19           ` Kees Cook
2017-04-21 23:28             ` Andy Lutomirski
2017-04-21 23:40               ` Kees Cook
2017-04-21 23:51                 ` Andy Lutomirski
2017-04-22  0:12                   ` Djalal Harouni
     [not found]                     ` <CAEiveUcx8fwQgXdLPeMNsTjX2KPhQKH__a-XzcHko_1aCmh4sg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-04-22  1:19                       ` Djalal Harouni
2017-04-22  6:51                       ` Andy Lutomirski
     [not found]                         ` <CALCETrUT73CcPQx2T=1zWbOUhw9r-c_YqXw5-KTwxgWPgXuTwA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-04-22 19:29                           ` Kees Cook
     [not found]                             ` <CAGXu5jLV+WZyj+xnxVFkFEgEthNt6eXdcSgHT-=85mJ1ECZ1Rw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-04-24 14:25                               ` Djalal Harouni
2017-04-24 18:02                                 ` Kees Cook
     [not found]                                   ` <CAGXu5jL_-cxidy_O4ORaN0iX9o7=hsi3DYTRvQs5w5363Z+MVg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-04-24 18:35                                     ` Djalal Harouni
2017-04-21 23:52               ` Casey Schaufler
2017-04-22  0:00                 ` Andy Lutomirski
2017-04-22  0:13                   ` Casey Schaufler
2017-04-22  6:45                     ` Andy Lutomirski
2017-04-22 12:17               ` Djalal Harouni
     [not found]                 ` <CAEiveUdbQcfn1xC5xWMv91vL_uR1MGTvARqw-E4GDTMUZ6t=bA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-04 13:07                   ` Djalal Harouni
2017-05-04 14:58                     ` Serge E. Hallyn
2017-05-05 13:06                       ` Djalal Harouni
2017-05-05 16:18                     ` Andy Lutomirski
2017-04-20  1:57   ` kbuild test robot
     [not found]   ` <1492640420-27345-3-git-send-email-tixxdz-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2017-04-19 22:38     ` Djalal Harouni
2017-04-24  4:29     ` Rusty Russell
2017-04-26  9:06       ` Djalal Harouni
2017-04-27  2:07         ` Rusty Russell
     [not found]           ` <87k266hacq.fsf-8n+1lVoiYb80n/F98K4Iww@public.gmane.org>
2017-04-27 13:16             ` Djalal Harouni

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