On Thu, Jan 30, 2014 at 2:07 PM, Vivek Goyal <vgo...@redhat.com> wrote: > On Sun, Jan 26, 2014 at 10:51:06PM -0800, H. Peter Anvin wrote: >> On 01/26/2014 10:49 PM, Richard Weinberger wrote: >> >> >> >> No, because that information is available to user space unless we panic. >> > >> > Didn't you mean non-root? >> > I thought one has to set dmesg_restrict anyways if kASLR is used. >> > >> > And isn't the offset available to perf too? >> > Of course only for root, but still user space. >> > >> >> For certain system security levels one want to protect even from a rogue >> root. In those cases, leaking that information via dmesg and perf isn't >> going to work, either. >> >> With lower security settings, by all means... > > I am wondering if kdump functionality is impacted with this change. > > Kexec tools prepares ELF headers for kernel memory ranges and for the > range where kernel text is mapped. So it needs to know virtual address > of the region where kernel is mapped (obtained by /proc/kcore) and > it gets the physical address where kernel is loaded from /proc/iomem. > > So with this change are we planning to hide kernel text virtual address and > physical address information information from root in /proc/kcore and > /proc/iomem in anyway?
I have no intention of that. Mentioned earlier in the thread, hiding it from root will be pretty ugly/hard/pointless: https://lkml.org/lkml/2014/1/27/287 I would like to just keep the offset out of dmesg. -Kees -- Kees Cook Chrome OS Security -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
