On Fri, Mar 15, 2013 at 9:55 AM, Johannes Weiner <hannes@xxxxxxxxxxx> wrote: > On Fri, Mar 15, 2013 at 08:48:49AM -0700, Luigi Semenzato wrote: >> On Fri, Mar 15, 2013 at 2:04 AM, Ric Mason <ric.masonn@xxxxxxxxx> wrote: >> > On 03/12/2013 07:57 AM, Luigi Semenzato wrote: >> >> >> >> Greetings linux-mmers, >> >> >> >> before we can fully deploy zram, we must ensure it conforms to the >> >> Chrome OS security requirements. In particular, we do not want to >> >> allow user space to read/write the swap device---not even root-owned >> >> processes. >> > >> > >> > Interesting. >> >> Thank you. >> >> >> >> >> A similar restriction is available for /dev/mem under >> >> CONFIG_STRICT_DEVMEM. >> > >> > >> > Sorry, what's /dev/mem used for? and why relevant your topic? >> >> I don't know what it's used for Chrome OS, but I don't think it >> matters. The point is that /dev/mem is compiled in the kernel, and >> without CONFIG_STRICT_DEVMEM it offers a way for a root-owned process >> to read/write all of physical memory. The situation is not as dire >> with a swap device, but currently a root-owned process can open a >> block device used for swap and peek and poke its data, which means >> that a root-owned process has now potential access to the data segment >> of any other process, among other things. > > How do you handle /proc/<pid>/mem? Right. We do not. But... we might! We could turn it off and see if it breaks anything important. In any case, we don't like expanding the attack surface. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>