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arm64, mm: make randomization selected by generic topdown mmap layout 

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>
This commit is contained in:
Alexandre Ghiti 2019-09-23 15:38:50 -07:00 committed by Linus Torvalds
parent 67f3977f80
commit e7142bf5d2
4 changed files with 10 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/Kconfig
View File

@ -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

1
arch/arm64/Kconfig
View File

@ -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

8
arch/arm64/kernel/process.c
View File

@ -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.
*/

11
mm/util.c
View File

@ -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)
{