Messages in this thread Patch in this message | | | Date | Tue, 24 Apr 2018 01:08:37 -0700 | From | tip-bot for Dave Hansen <> | Subject | [tip:x86/pti] x86/pti: Disallow global kernel text with RANDSTRUCT |
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Commit-ID: 26d35ca6c3776784f8156e1d6f80cc60d9a2a915 Gitweb: https://git.kernel.org/tip/26d35ca6c3776784f8156e1d6f80cc60d9a2a915 Author: Dave Hansen <dave.hansen@linux.intel.com> AuthorDate: Fri, 20 Apr 2018 15:20:26 -0700 Committer: Thomas Gleixner <tglx@linutronix.de> 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 <keescook@google.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Ingo Molnar <mingo@kernel.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Hugh Dickins <hughd@google.com> Cc: linux-mm@kvack.org Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Nadav Amit <namit@vmware.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Link: https://lkml.kernel.org/r/20180420222026.D0B4AAC9@viggo.jf.intel.com
--- 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; }
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