Commit e39f5602 authored by David Daney's avatar David Daney Committed by Linus Torvalds
Browse files

fs: binfmt_elf: create Kconfig variable for PIE randomization 



Randomization of PIE load address is hard coded in binfmt_elf.c for X86
and ARM.  Create a new Kconfig variable
(CONFIG_ARCH_BINFMT_ELF_RANDOMIZE_PIE) for this and use it instead.  Thus
architecture specific policy is pushed out of the generic binfmt_elf.c and
into the architecture Kconfig files.

X86 and ARM Kconfigs are modified to select the new variable so there is
no change in behavior.  A follow on patch will select it for MIPS too.

Signed-off-by: default avatarDavid Daney <david.daney@cavium.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Acked-by: default avatarH. Peter Anvin <hpa@zytor.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 5742332d

arch/arm/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ config ARM 
	select HAVE_FTRACE_MCOUNT_RECORD if (!XIP_KERNEL)

	select HAVE_DYNAMIC_FTRACE if (!XIP_KERNEL)

	select HAVE_FUNCTION_GRAPH_TRACER if (!THUMB2_KERNEL)

	select ARCH_BINFMT_ELF_RANDOMIZE_PIE

	select HAVE_GENERIC_DMA_COHERENT

	select HAVE_KERNEL_GZIP

	select HAVE_KERNEL_LZO

arch/x86/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -62,6 +62,7 @@ config X86 
	select ANON_INODES

	select HAVE_ARCH_KMEMCHECK

	select HAVE_USER_RETURN_NOTIFIER

	select ARCH_BINFMT_ELF_RANDOMIZE_PIE

	select HAVE_ARCH_JUMP_LABEL

	select HAVE_TEXT_POKE_SMP

	select HAVE_GENERIC_HARDIRQS

fs/Kconfig.binfmt

+3 −0
Original line number Diff line number Diff line
@@ -27,6 +27,9 @@ config COMPAT_BINFMT_ELF 
	bool

	depends on COMPAT && BINFMT_ELF



config ARCH_BINFMT_ELF_RANDOMIZE_PIE

	bool



config BINFMT_ELF_FDPIC

	bool "Kernel support for FDPIC ELF binaries"

	default y

fs/binfmt_elf.c

+1 −1
Original line number Diff line number Diff line
@@ -794,7 +794,7 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs) 
			 * default mmap base, as well as whatever program they

			 * might try to exec.  This is because the brk will

			 * follow the loader, and is not movable.  */

#if defined(CONFIG_X86) || defined(CONFIG_ARM)

#ifdef CONFIG_ARCH_BINFMT_ELF_RANDOMIZE_PIE

			/* Memory randomization might have been switched off

			 * in runtime via sysctl.

			 * If that is the case, retain the original non-zero

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