linux-kernel - Re: [Patch] kexec_load: check CAP_SYS

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Message-ID: <m1bp3uifln.fsf@fess.ebiederm.org>
Date:	Thu, 06 Jan 2011 00:47:00 -0800
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Amerigo Wang <amwang@...hat.com>
Cc:	linux-kernel@...r.kernel.org, kexec@...ts.infradead.org
Subject: Re: [Patch] kexec_load: check CAP_SYS_MODULE

Amerigo Wang <amwang@...hat.com> writes:

> Eric pointed out that kexec_load() actually allows you to
> run any code you want in ring0, this is more like CAP_SYS_MODULE.

Let me get this straight you want to make the permission checks
less stringent by allowing either CAP_SYS_MODULE or CAP_SYS_BOOT?

CAP_SYS_BOOT is the correct capability.  Sure you can run any
code but only after rebooting.  I don't see how this differs
from any other reboot scenario.

Eric

> Reported-by: Eric Paris <eparis@...hat.com>
> Signed-off-by: WANG Cong <amwang@...hat.com>
>
> ---
> diff --git a/kernel/kexec.c b/kernel/kexec.c
> index b55045b..c30d613 100644
> --- a/kernel/kexec.c
> +++ b/kernel/kexec.c
> @@ -945,7 +945,7 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments,
>  	int result;
>  
>  	/* We only trust the superuser with rebooting the system. */
> -	if (!capable(CAP_SYS_BOOT))
> +	if (!capable(CAP_SYS_BOOT) || !capable(CAP_SYS_MODULE))
>  		return -EPERM;
>  
>  	/*
--
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