Commit-ID: 26d35ca6c3776784f8156e1d6f80cc60d9a2a915 Gitweb: https://git.kernel.org/tip/26d35ca6c3776784f8156e1d6f80cc60d9a2a915 Author: Dave Hansen <[email protected]> AuthorDate: Fri, 20 Apr 2018 15:20:26 -0700 Committer: Thomas Gleixner <[email protected]> CommitDate: Tue, 24 Apr 2018 09:50:54 +0200
x86/pti: Disallow global kernel text with RANDSTRUCT RANDSTRUCT derives its hardening benefits from the attacker's lack of knowledge about the layout of kernel data structures. Keep the kernel image non-global in cases where RANDSTRUCT is in use to help keep the layout a secret. Fixes: 8c06c7740 (x86/pti: Leave kernel text global for !PCID) Reported-by: Kees Cook <[email protected]> Signed-off-by: Dave Hansen <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Acked-by: Ingo Molnar <[email protected]> Cc: Andrea Arcangeli <[email protected]> Cc: Juergen Gross <[email protected]> Cc: Josh Poimboeuf <[email protected]> Cc: Greg Kroah-Hartman <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: David Woodhouse <[email protected]> Cc: Hugh Dickins <[email protected]> Cc: [email protected] Cc: Linus Torvalds <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Nadav Amit <[email protected]> Cc: Dan Williams <[email protected]> Cc: Arjan van de Ven <[email protected]> Cc: Vlastimil Babka <[email protected]> Link: https://lkml.kernel.org/r/[email protected] --- arch/x86/mm/pti.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c index ae3eb4f5d53b..4d418e705878 100644 --- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -421,6 +421,16 @@ static inline bool pti_kernel_image_global_ok(void) if (boot_cpu_has(X86_FEATURE_K8)) return false; + /* + * RANDSTRUCT derives its hardening benefits from the + * attacker's lack of knowledge about the layout of kernel + * data structures. Keep the kernel image non-global in + * cases where RANDSTRUCT is in use to help keep the layout a + * secret. + */ + if (IS_ENABLED(CONFIG_GCC_PLUGIN_RANDSTRUCT)) + return false; + return true; }
