diff mbox

[v3,27/31] x86: Implement thread_struct whitelist for hardened usercopy

Message ID 1505940337-79069-28-git-send-email-keescook@chromium.org (mailing list archive)
State New, archived
Headers show

Commit Message

Kees Cook Sept. 20, 2017, 8:45 p.m. UTC 
This whitelists the FPU register state portion of the thread_struct for
copying to userspace, instead of the default entire struct.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Cc: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Mathias Krause <minipli@googlemail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Rik van Riel <riel@redhat.com>
---
 arch/x86/Kconfig                 | 1 +
 arch/x86/include/asm/processor.h | 8 ++++++++
 2 files changed, 9 insertions(+)
diff mbox

Patch

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 971feac13506..6642e8eaff45 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -114,6 +114,7 @@  config X86
 	select HAVE_ARCH_MMAP_RND_COMPAT_BITS	if MMU && COMPAT
 	select HAVE_ARCH_COMPAT_MMAP_BASES	if MMU && COMPAT
 	select HAVE_ARCH_SECCOMP_FILTER
+	select HAVE_ARCH_THREAD_STRUCT_WHITELIST
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 3fa26a61eabc..868235b967ed 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -488,6 +488,14 @@  struct thread_struct {
 	 */
 };
 
+/* Whitelist the FPU state from the task_struct for hardened usercopy. */
+static inline void arch_thread_struct_whitelist(unsigned long *offset,
+						unsigned long *size)
+{
+	*offset = offsetof(struct thread_struct, fpu.state);
+	*size = fpu_kernel_xstate_size;
+}
+
 /*
  * Thread-synchronous status.
  *