Commit 9e8084d3 authored Aug 16, 2017 by Kees Cook

arm64: Implement thread_struct whitelist for hardened usercopy

While ARM64 carries FPU state in the thread structure that is saved and
restored during signal handling, it doesn't need to declare a usercopy
whitelist, since existing accessors are all either using a bounce buffer
(for which whitelisting isn't checking the slab), are statically sized
(which will bypass the hardened usercopy check), or both.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: James Morse <james.morse@arm.com>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Dave Martin <Dave.Martin@arm.com>
Cc: zijun_hu <zijun_hu@htc.com>
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Kees Cook <keescook@chromium.org>

parent f7d83c1c

arch/arm64/Kconfig

+1 −0

Original line number	Diff line number	Diff line
		@@ -90,6 +90,7 @@ config ARM64
		select HAVE_ARCH_MMAP_RND_BITS
		select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
		select HAVE_ARCH_SECCOMP_FILTER
		select HAVE_ARCH_THREAD_STRUCT_WHITELIST
		select HAVE_ARCH_TRACEHOOK
		select HAVE_ARCH_TRANSPARENT_HUGEPAGE
		select HAVE_ARCH_VMAP_STACK

arch/arm64/include/asm/processor.h

+10 −0

Original line number	Diff line number	Diff line
		@@ -113,6 +113,16 @@ struct thread_struct {
		struct debug_info debug; /* debugging */
		};

		/*
		* Everything usercopied to/from thread_struct is statically-sized, so
		* no hardened usercopy whitelist is needed.
		*/
		static inline void arch_thread_struct_whitelist(unsigned long *offset,
		unsigned long *size)
		{
		offset = size = 0;
		}

		#ifdef CONFIG_COMPAT
		#define task_user_tls(t) \
		({ \

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