arm64, mm: make randomization selected by generic topdown mmap layout (e7142bf5) · Commits · 戴 / test

This commits selects ARCH_HAS_ELF_RANDOMIZE when an arch uses the generic topdown mmap layout functions so that this security feature is on by default. Note that this commit also removes the possibility for arm64 to have elf randomization and no MMU: without MMU, the security added by randomization is worth nothing. Link: http://lkml.kernel.org/r/20190730055113.23635-6-alex@ghiti.fr Signed-off-by:

Alexandre Ghiti <alex@ghiti.fr> Acked-by:

Catalin Marinas <catalin.marinas@arm.com> Acked-by:

Kees Cook <keescook@chromium.org> Reviewed-by:

Christoph Hellwig <hch@lst.de> Reviewed-by:

Luis Chamberlain <mcgrof@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@infradead.org> Cc: James Hogan <jhogan@kernel.org> Cc: Palmer Dabbelt <palmer@sifive.com> Cc: Paul Burton <paul.burton@mips.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

arch/Kconfig

+1 −0

Original line number	Diff line number	Diff line
		@@ -715,6 +715,7 @@ config HAVE_ARCH_COMPAT_MMAP_BASES
		config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
		bool
		depends on MMU
		select ARCH_HAS_ELF_RANDOMIZE

		config HAVE_COPY_THREAD_TLS
		bool

arch/arm64/Kconfig

+0 −1

Original line number	Diff line number	Diff line
		@@ -15,7 +15,6 @@ config ARM64
		select ARCH_HAS_DMA_COHERENT_TO_PFN
		select ARCH_HAS_DMA_PREP_COHERENT
		select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
		select ARCH_HAS_ELF_RANDOMIZE
		select ARCH_HAS_FAST_MULTIPLIER
		select ARCH_HAS_FORTIFY_SOURCE
		select ARCH_HAS_GCOV_PROFILE_ALL

arch/arm64/kernel/process.c

+0 −8

Original line number	Diff line number	Diff line
		@@ -557,14 +557,6 @@ unsigned long arch_align_stack(unsigned long sp)
		return sp & ~0xf;
		}

		unsigned long arch_randomize_brk(struct mm_struct *mm)
		{
		if (is_compat_task())
		return randomize_page(mm->brk, SZ_32M);
		else
		return randomize_page(mm->brk, SZ_1G);
		}

		/*
		* Called from setup_new_exec() after (COMPAT_)SET_PERSONALITY.
		*/

mm/util.c

+9 −2

Original line number	Diff line number	Diff line
		@@ -321,7 +321,15 @@ unsigned long randomize_stack_top(unsigned long stack_top)
		}

		#ifdef CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
		#ifdef CONFIG_ARCH_HAS_ELF_RANDOMIZE
		unsigned long arch_randomize_brk(struct mm_struct *mm)
		{
		/* Is the current task 32bit ? */
		if (!IS_ENABLED(CONFIG_64BIT) \|\| is_compat_task())
		return randomize_page(mm->brk, SZ_32M);

		return randomize_page(mm->brk, SZ_1G);
		}

		unsigned long arch_mmap_rnd(void)
		{
		unsigned long rnd;
		@@ -335,7 +343,6 @@ unsigned long arch_mmap_rnd(void)

		return rnd << PAGE_SHIFT;
		}
		#endif /* CONFIG_ARCH_HAS_ELF_RANDOMIZE */

		static int mmap_is_legacy(struct rlimit *rlim_stack)
		{

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