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| author | Alexandre Ghiti <alex@ghiti.fr> | 2019-09-24 00:38:50 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-09-25 00:54:11 +0200 |
| commit | e7142bf5d231f3ccdf6ea6764d5080999b8e299d (patch) | |
| tree | 3401d4fe9800da087ab54c7c7bc4189c1b6b0d49 /mm | |
| parent | arm64, mm: move generic mmap layout functions to mm (diff) | |
| download | linux-e7142bf5d231f3ccdf6ea6764d5080999b8e299d.tar.xz linux-e7142bf5d231f3ccdf6ea6764d5080999b8e299d.zip | |
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>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/util.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/mm/util.c b/mm/util.c index 7922726f0a8f..3ad6db9a722e 100644 --- a/mm/util.c +++ b/mm/util.c @@ -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) { |