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-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
