[PATCH 3.19.y-ckt 15/54] mm: fold arch_randomize_brk into ARCH_HAS_ELF_RANDOMIZE

From: Kamal Mostafa
Date: Mon May 09 2016 - 20:06:52 EST

3.19.8-ckt21 -stable review patch. If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Kees Cook <keescook@xxxxxxxxxxxx>

commit 204db6ed17743000691d930368a5abd6ea541c58 upstream.

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@xxxxxxxxxxxx>
Cc: Hector Marco-Gisbert <hecmargi@xxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
Reviewed-by: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: "David A. Long" <dave.long@xxxxxxxxxx>
Cc: Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx>
Cc: Arun Chandran <achandran@xxxxxxxxxx>
Cc: Yann Droneaud <ydroneaud@xxxxxxxxxx>
Cc: Min-Hua Chen <orca.chen@xxxxxxxxx>
Cc: Paul Burton <paul.burton@xxxxxxxxxx>
Cc: Alex Smith <alex@xxxxxxxxxxxxxxxx>
Cc: Markos Chandras <markos.chandras@xxxxxxxxxx>
Cc: Vineeth Vijayan <vvijayan@xxxxxxxxxx>
Cc: Jeff Bailey <jeffbailey@xxxxxxxxxx>
Cc: Michael Holzheu <holzheu@xxxxxxxxxxxxxxxxxx>
Cc: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Cc: Behan Webster <behanw@xxxxxxxxxxxxxxxxxx>
Cc: Ismael Ripoll <iripoll@xxxxxx>
Cc: Jan-Simon Mller <dl9pf@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
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 9ff5aa8..d4f270a 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 674d03f..1984a92 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 f724db0..faad6df 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 eb4d95d..a4a2b07 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 57d289a..ee46ffe 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 d0db9d9..fdda72e 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 ca3347a..bbdace2 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 41bf972..03ca452 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1050,15 +1050,13 @@ 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 7a4eda0..b5f0bda 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
--
2.7.4