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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: Kees Cook <keescook@chromium.org>
Acked-by: Rik van Riel <riel@redhat.com>
This commit is contained in:
Kees Cook 2017-08-16 13:26:03 -07:00
parent 5905429ad8
commit f7d83c1cf3
2 changed files with 9 additions and 0 deletions
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1
arch/x86/Kconfig
View File

@ -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

8
arch/x86/include/asm/processor.h
View File

@ -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.
*