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Commit f7d83c1c authored by Kees Cook's avatar Kees Cook
Browse files

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. This is needed
because FPU register state is dynamically sized, so it doesn't bypass the
hardened usercopy checks.

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: default avatarKees Cook <keescook@chromium.org>
Acked-by: default avatarRik van Riel <riel@redhat.com>
parent 5905429a

arch/x86/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -116,6 +116,7 @@ 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

arch/x86/include/asm/processor.h

+8 −0
Original line number Diff line number Diff line
@@ -492,6 +492,14 @@ 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.

 *