On Tue, Oct 2, 2012 at 10:12 PM, David Rientjes <rient...@google.com> wrote: > On Tue, 2 Oct 2012, Kees Cook wrote: > >> In the paranoid case of sysctl kernel.kptr_restrict=2, mask the kernel >> virtual addresses in /proc/vmallocinfo too. >> >> Reported-by: Brad Spengler <spen...@grsecurity.net> >> Signed-off-by: Kees Cook <keesc...@chromium.org> > > /proc/vmallocinfo is S_IRUSR, not S_IRUGO, so exactly what are you trying > to protect?
Trying to block the root user from seeing virtual memory addresses (mode 2 of kptr_restrict). Documentation/sysctl/kernel.txt: "This toggle indicates whether restrictions are placed on exposing kernel addresses via /proc and other interfaces. When kptr_restrict is set to (0), there are no restrictions. When kptr_restrict is set to (1), the default, kernel pointers printed using the %pK format specifier will be replaced with 0's unless the user has CAP_SYSLOG. When kptr_restrict is set to (2), kernel pointers printed using %pK will be replaced with 0's regardless of privileges." Even though it's S_IRUSR, it still needs %pK for the paranoid case. -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/
