From e9ea1e7f53b852147cbd568b0568c7ad97ec21a3 Mon Sep 17 00:00:00 2001 From: Kyle Huey Date: Mon, 20 Mar 2017 01:16:26 -0700 Subject: x86/arch_prctl: Add ARCH_[GET|SET]_CPUID MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Intel supports faulting on the CPUID instruction beginning with Ivy Bridge. When enabled, the processor will fault on attempts to execute the CPUID instruction with CPL>0. Exposing this feature to userspace will allow a ptracer to trap and emulate the CPUID instruction. When supported, this feature is controlled by toggling bit 0 of MSR_MISC_FEATURES_ENABLES. It is documented in detail in Section 2.3.2 of https://bugzilla.kernel.org/attachment.cgi?id=243991 Implement a new pair of arch_prctls, available on both x86-32 and x86-64. ARCH_GET_CPUID: Returns the current CPUID state, either 0 if CPUID faulting is enabled (and thus the CPUID instruction is not available) or 1 if CPUID faulting is not enabled. ARCH_SET_CPUID: Set the CPUID state to the second argument. If cpuid_enabled is 0 CPUID faulting will be activated, otherwise it will be deactivated. Returns ENODEV if CPUID faulting is not supported on this system. The state of the CPUID faulting flag is propagated across forks, but reset upon exec. Signed-off-by: Kyle Huey Cc: Grzegorz Andrejczuk Cc: kvm@vger.kernel.org Cc: Radim Krčmář Cc: Peter Zijlstra Cc: Dave Hansen Cc: Andi Kleen Cc: linux-kselftest@vger.kernel.org Cc: Nadav Amit Cc: Robert O'Callahan Cc: Richard Weinberger Cc: "Rafael J. Wysocki" Cc: Borislav Petkov Cc: Andy Lutomirski Cc: Len Brown Cc: Shuah Khan Cc: user-mode-linux-devel@lists.sourceforge.net Cc: Jeff Dike Cc: Alexander Viro Cc: user-mode-linux-user@lists.sourceforge.net Cc: David Matlack Cc: Boris Ostrovsky Cc: Dmitry Safonov Cc: linux-fsdevel@vger.kernel.org Cc: Paolo Bonzini Link: http://lkml.kernel.org/r/20170320081628.18952-9-khuey@kylehuey.com Signed-off-by: Thomas Gleixner --- include/linux/thread_info.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include/linux/thread_info.h') diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h index 58373875e8ee..55125d674338 100644 --- a/include/linux/thread_info.h +++ b/include/linux/thread_info.h @@ -101,6 +101,10 @@ static inline void check_object_size(const void *ptr, unsigned long n, { } #endif /* CONFIG_HARDENED_USERCOPY */ +#ifndef arch_setup_new_exec +static inline void arch_setup_new_exec(void) { } +#endif + #endif /* __KERNEL__ */ #endif /* _LINUX_THREAD_INFO_H */ -- cgit v1.2.3 From 96dc4f9fb64690fc34410415fd1fc609cf803f61 Mon Sep 17 00:00:00 2001 From: Sahara Date: Thu, 16 Feb 2017 18:29:15 +0000 Subject: usercopy: Move enum for arch_within_stack_frames() This patch moves the arch_within_stack_frames() return value enum up in the header files so that per-architecture implementations can reuse the same return values. Signed-off-by: Sahara Signed-off-by: James Morse [kees: adjusted naming and commit log] Signed-off-by: Kees Cook --- arch/x86/include/asm/thread_info.h | 13 +++++++------ include/linux/thread_info.h | 12 ++++++++++++ mm/usercopy.c | 8 +------- 3 files changed, 20 insertions(+), 13 deletions(-) (limited to 'include/linux/thread_info.h') diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h index ad6f5eb07a95..920ca1f7adea 100644 --- a/arch/x86/include/asm/thread_info.h +++ b/arch/x86/include/asm/thread_info.h @@ -168,9 +168,9 @@ static inline unsigned long current_stack_pointer(void) * entirely contained by a single stack frame. * * Returns: - * 1 if within a frame - * -1 if placed across a frame boundary (or outside stack) - * 0 unable to determine (no frame pointers, etc) + * GOOD_FRAME if within a frame + * BAD_STACK if placed across a frame boundary (or outside stack) + * NOT_STACK unable to determine (no frame pointers, etc) */ static inline int arch_within_stack_frames(const void * const stack, const void * const stackend, @@ -197,13 +197,14 @@ static inline int arch_within_stack_frames(const void * const stack, * the copy as invalid. */ if (obj + len <= frame) - return obj >= oldframe + 2 * sizeof(void *) ? 1 : -1; + return obj >= oldframe + 2 * sizeof(void *) ? + GOOD_FRAME : BAD_STACK; oldframe = frame; frame = *(const void * const *)frame; } - return -1; + return BAD_STACK; #else - return 0; + return NOT_STACK; #endif } diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h index 58373875e8ee..0dbe41be6181 100644 --- a/include/linux/thread_info.h +++ b/include/linux/thread_info.h @@ -22,6 +22,18 @@ #endif #include + +/* + * For per-arch arch_within_stack_frames() implementations, defined in + * asm/thread_info.h. + */ +enum { + BAD_STACK = -1, + NOT_STACK = 0, + GOOD_FRAME, + GOOD_STACK, +}; + #include #ifdef __KERNEL__ diff --git a/mm/usercopy.c b/mm/usercopy.c index d155e12563b1..1eba99baf1cf 100644 --- a/mm/usercopy.c +++ b/mm/usercopy.c @@ -19,15 +19,9 @@ #include #include #include +#include #include -enum { - BAD_STACK = -1, - NOT_STACK = 0, - GOOD_FRAME, - GOOD_STACK, -}; - /* * Checks if a given pointer and length is contained by the current * stack frame (if possible). -- cgit v1.2.3