linux-kernel - Re: [PATCH 01/12] Security: Add CAP_COMPROMISE

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 19 Mar 2013 18:02:53 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Matthew Garrett <matthew.garrett@...ula.com>
CC:	linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org, linux-efi@...r.kernel.org,
	kexec@...ts.infradead.org, linux-pci@...r.kernel.org
Subject: Re: [PATCH 01/12] Security: Add CAP_COMPROMISE_KERNEL

On 03/18/2013 02:32 PM, Matthew Garrett wrote:
> 
> This means we can return our focus to the kernel. There's currently a number
> of kernel interfaces that permit privileged userspace to modify the running
> kernel. These are currently protected by CAP_SYS_RAWIO, but unfortunately
> the semantics of this capability are poorly defined and it now covers a large
> superset of the desired behaviour.
> 

... except it doesn't.

Looking at it in detail, EVERYTHING in CAP_SYS_RAWIO has the possibility
of compromising the kernel, because they let device drivers be bypassed,
which means arbitrary DMA, which means you have everything.

Now, a lot of the abuses of CAP_SYS_RAWIO have clearly been added by
people who had *no bloody clue* what that capability meant, but it
really doesn't change the fact that pretty much if you have
CAP_SYS_RAWIO you have the machine.

So just reject CAP_SYS_RAWIO.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/