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: David Daney <[email protected]> Cc: Russell King <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: Alexander Viro <[email protected]> Acked-by: H. Peter Anvin <[email protected]> Cc: Ralf Baechle <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
alberto-fc · Jan 11, 2012 · e39f560 · e39f560
1 parent 5742332
commit e39f560
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Showing 4 changed files with 6 additions and 1 deletion.
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
@@ -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

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
@@ -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

diff --git a/fs/Kconfig.binfmt b/fs/Kconfig.binfmt
@@ -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

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
@@ -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