From mboxrd@z Thu Jan 1 00:00:00 1970 Reply-To: kernel-hardening@lists.openwall.com From: Kees Cook Date: Wed, 25 Nov 2015 15:31:22 -0800 Message-Id: <1448494286-16029-1-git-send-email-keescook@chromium.org> Subject: [kernel-hardening] [PATCH v2 0/4] introduce post-init read-only memory To: linux-kernel@vger.kernel.org Cc: Kees Cook , Andy Lutomirski , "H. Peter Anvin" , Michael Ellerman , Mathias Krause , Ingo Molnar , Thomas Gleixner , x86@kernel.org, Arnd Bergmann , PaX Team , Emese Revfy , kernel-hardening@lists.openwall.com, linux-arch List-ID: One of the easiest ways to protect the kernel from attack is to reduce the internal attack surface exposed when a "write" flaw is available. By making as much of the kernel read-only as possible, we reduce the attack surface. Many things are written to only during __init, and never changed again. These cannot be made "const" since the compiler will do the wrong thing (we do actually need to write to them). Instead, move these items into a memory region that will be made read-only during mark_rodata_ro() which happens after all kernel __init code has finished. This introduces __ro_after_init as a way to mark such memory, and uses it on the x86 vDSO to kill an extant kernel exploitation method. Also adds a new kernel parameter to help debug future use and adds an lkdtm test to check the results. -Kees