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Message-Id: <1503956111-36652-28-git-send-email-keescook@chromium.org>
Date: Mon, 28 Aug 2017 14:35:08 -0700
From: Kees Cook <keescook@...omium.org>
To: linux-kernel@...r.kernel.org
Cc: Kees Cook <keescook@...omium.org>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>,
x86@...nel.org,
Borislav Petkov <bp@...e.de>,
Andy Lutomirski <luto@...nel.org>,
Mathias Krause <minipli@...glemail.com>,
linux-mm@...ck.org,
kernel-hardening@...ts.openwall.com,
David Windsor <dave@...lcore.net>
Subject: [PATCH v2 27/30] x86: Implement thread_struct whitelist for hardened usercopy
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@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: x86@...nel.org
Cc: Borislav Petkov <bp@...e.de>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Mathias Krause <minipli@...glemail.com>
Signed-off-by: Kees Cook <keescook@...omium.org>
---
arch/x86/Kconfig | 1 +
arch/x86/include/asm/processor.h | 8 ++++++++
2 files changed, 9 insertions(+)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 781521b7cf9e..a8793721483c 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -113,6 +113,7 @@ 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 028245e1c42b..dc52ba90f090 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -481,6 +481,14 @@ 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.
*
--
2.7.4
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