Re: [PATCH 01/12] Security: Add CAP_COMPROMISE_KERNEL

[H. Peter Anvin]

CAP_SYS_RAWIO is definitely inappropriate there.

Matthew Garrett <matthew.garrett@xxxxxxxxxx> wrote:

>On Tue, 2013-03-19 at 18:02 -0700, H. Peter Anvin wrote:
>
>> 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.
>
>Having checked again, I don't think this is true. The most obvious case
>is libata, which uses CAP_SYS_RAWIO to limit the ability to send raw
>ATA
>commands. Being able to do so clearly permits userspace to avoid any
>kind of policy the vfs has put in place, but there's no obvious way for
>the user to modify the running kernel. Are you suggesting that removing
>the CAP_SYS_RAWIO check there would be reasonable?

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