[PATCH v4 10/10] mm: fold arch_randomize_brk into ARCH_HAS_ELF_RANDOMIZE

Kees Cook
2015-03-04T21:13:13Z

The arch_randomize_brk() function is used on several architectures,
even those that don't support ET_DYN ASLR. To avoid bulky extern/#define
tricks, consolidate the support under CONFIG_ARCH_HAS_ELF_RANDOMIZE for
the architectures that support it, while still handling CONFIG_COMPAT_BRK.

Signed-off-by: Kees Cook <keescook@chromium.org>
---
arch/Kconfig | 1 +
arch/arm/include/asm/elf.h | 4 ----
arch/arm64/include/asm/elf.h | 4 ----
arch/mips/include/asm/elf.h | 4 ----
arch/powerpc/include/asm/elf.h | 4 ----
arch/s390/include/asm/elf.h | 3 ---
arch/x86/include/asm/elf.h | 3 ---
fs/binfmt_elf.c | 4 +---
include/linux/elf-randomize.h | 12 ++++++++++++
9 files changed, 14 insertions(+), 25 deletions(-)

diff --git a/arch/Kconfig b/arch/Kconfig
index 9ff5aa8fa2c1..d4f270a54fe6 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -490,6 +490,7 @@ config ARCH_HAS_ELF_RANDOMIZE
An architecture supports choosing randomized locations for
stack, mmap, brk, and ET_DYN. Defined functions:
- arch_mmap_rnd()
+ - arch_randomize_brk()

#
# ABI hall of shame
diff --git a/arch/arm/include/asm/elf.h b/arch/arm/include/asm/elf.h
index afb9cafd3786..c1ff8ab12914 100644
--- a/arch/arm/include/asm/elf.h
+++ b/arch/arm/include/asm/elf.h
@@ -125,10 +125,6 @@ int dump_task_regs(struct task_struct *t, elf_gregset_t *elfregs);
extern void elf_set_personality(const struct elf32_hdr *);
#define SET_PERSONALITY(ex) elf_set_personality(&(ex))

-struct mm_struct;
-extern unsigned long arch_randomize_brk(struct mm_struct *mm);
-#define arch_randomize_brk arch_randomize_brk
-
#ifdef CONFIG_MMU
#define ARCH_HAS_SETUP_ADDITIONAL_PAGES 1
struct linux_binprm;
diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h
index f724db00b235..faad6df49e5b 100644
--- a/arch/arm64/include/asm/elf.h
+++ b/arch/arm64/include/asm/elf.h
@@ -156,10 +156,6 @@ extern int arch_setup_additional_pages(struct linux_binprm *bprm,
#define STACK_RND_MASK (0x3ffff >> (PAGE_SHIFT - 12))
#endif

-struct mm_struct;
-extern unsigned long arch_randomize_brk(struct mm_struct *mm);
-#define arch_randomize_brk arch_randomize_brk
-
#ifdef CONFIG_COMPAT

#ifdef __AARCH64EB__
diff --git a/arch/mips/include/asm/elf.h b/arch/mips/include/asm/elf.h
index 535f196ffe02..31d747d46a23 100644
--- a/arch/mips/include/asm/elf.h
+++ b/arch/mips/include/asm/elf.h
@@ -410,10 +410,6 @@ struct linux_binprm;
extern int arch_setup_additional_pages(struct linux_binprm *bprm,
int uses_interp);

-struct mm_struct;
-extern unsigned long arch_randomize_brk(struct mm_struct *mm);
-#define arch_randomize_brk arch_randomize_brk
-
struct arch_elf_state {
int fp_abi;
int interp_fp_abi;
diff --git a/arch/powerpc/include/asm/elf.h b/arch/powerpc/include/asm/elf.h
index 57d289acb803..ee46ffef608e 100644
--- a/arch/powerpc/include/asm/elf.h
+++ b/arch/powerpc/include/asm/elf.h
@@ -128,10 +128,6 @@ extern int arch_setup_additional_pages(struct linux_binprm *bprm,
(0x7ff >> (PAGE_SHIFT - 12)) : \
(0x3ffff >> (PAGE_SHIFT - 12)))

-extern unsigned long arch_randomize_brk(struct mm_struct *mm);
-#define arch_randomize_brk arch_randomize_brk
-
-
#ifdef CONFIG_SPU_BASE
/* Notes used in ET_CORE. Note name is "SPU/<fd>/<filename>". */
#define NT_SPU 1
diff --git a/arch/s390/include/asm/elf.h b/arch/s390/include/asm/elf.h
index d0db9d944b6d..fdda72e56404 100644
--- a/arch/s390/include/asm/elf.h
+++ b/arch/s390/include/asm/elf.h
@@ -226,9 +226,6 @@ struct linux_binprm;
#define ARCH_HAS_SETUP_ADDITIONAL_PAGES 1
int arch_setup_additional_pages(struct linux_binprm *, int);

-extern unsigned long arch_randomize_brk(struct mm_struct *mm);
-#define arch_randomize_brk arch_randomize_brk
-
void *fill_cpu_elf_notes(void *ptr, struct save_area *sa, __vector128 *vxrs);

#endif
diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
index ca3347a9dab5..bbdace22daf8 100644
--- a/arch/x86/include/asm/elf.h
+++ b/arch/x86/include/asm/elf.h
@@ -338,9 +338,6 @@ extern int compat_arch_setup_additional_pages(struct linux_binprm *bprm,
int uses_interp);
#define compat_arch_setup_additional_pages compat_arch_setup_additional_pages

-extern unsigned long arch_randomize_brk(struct mm_struct *mm);
-#define arch_randomize_brk arch_randomize_brk
-
/*
* True on X86_32 or when emulating IA32 on X86_64
*/
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 6f08f5fa99dc..a115da230ce0 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1043,15 +1043,13 @@ static int load_elf_binary(struct linux_binprm *bprm)
current->mm->end_data = end_data;
current->mm->start_stack = bprm->p;

-#ifdef arch_randomize_brk
if ((current->flags & PF_RANDOMIZE) && (randomize_va_space > 1)) {
current->mm->brk = current->mm->start_brk =
arch_randomize_brk(current->mm);
-#ifdef CONFIG_COMPAT_BRK
+#ifdef compat_brk_randomized
current->brk_randomized = 1;
#endif
}
-#endif

if (current->personality & MMAP_PAGE_ZERO) {
/* Why this, you ask??? Well SVr4 maps page 0 as read-only,
diff --git a/include/linux/elf-randomize.h b/include/linux/elf-randomize.h
index 7a4eda02d2b1..b5f0bda9472e 100644
--- a/include/linux/elf-randomize.h
+++ b/include/linux/elf-randomize.h
@@ -1,10 +1,22 @@
#ifndef _ELF_RANDOMIZE_H
#define _ELF_RANDOMIZE_H

+struct mm_struct;
+
#ifndef CONFIG_ARCH_HAS_ELF_RANDOMIZE
static inline unsigned long arch_mmap_rnd(void) { return 0; }
+# if defined(arch_randomize_brk) && defined(CONFIG_COMPAT_BRK)
+# define compat_brk_randomized
+# endif
+# ifndef arch_randomize_brk
+# define arch_randomize_brk(mm) (mm->brk)
+# endif
#else
extern unsigned long arch_mmap_rnd(void);
+extern unsigned long arch_randomize_brk(struct mm_struct *mm);
+# ifdef CONFIG_COMPAT_BRK
+# define compat_brk_randomized
+# endif
#endif

#endif
--
1.9.1