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authorAlexandre Ghiti <alex@ghiti.fr>2019-09-23 15:38:50 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-09-24 15:54:11 -0700
commite7142bf5d231f3ccdf6ea6764d5080999b8e299d (patch)
tree3401d4fe9800da087ab54c7c7bc4189c1b6b0d49
parent67f3977f805b34cf0e41090679800d2091d41d49 (diff)
downloadlinux-e7142bf5d231f3ccdf6ea6764d5080999b8e299d.tar.gz
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>
-rw-r--r--arch/Kconfig1
-rw-r--r--arch/arm64/Kconfig1
-rw-r--r--arch/arm64/kernel/process.c8
-rw-r--r--mm/util.c11
4 files changed, 10 insertions, 11 deletions
diff --git a/arch/Kconfig b/arch/Kconfig
index dfce421b8e8a..5f8a5d84dbbe 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -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
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 2d4b7044063c..866e05882799 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -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
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 03689c0beb34..a47462def04b 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -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.
*/
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)
{