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 <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: H. Peter Anvin <hpa@zytor.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 561e33aac6c06f41c1d7e2ea5050e5ddbee16279..1e17b6cd28053f202546656bfac59dc591d38c8f 100644 (file)
--- 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
index 576bd084b0daabdccc7a5a42a4a219d29b6b5ee1..07b28c4346e9310542d2dfda3fff2dc31ef84f15 100644 (file)
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -65,6 +65,7 @@ config X86
        select HAVE_CMPXCHG_DOUBLE
        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
index 79e2ca7973b7a2b503a7f7fc168f716a5f6c0284..e95d1b64082cae708f3213a453ea3275f6afbb57 100644 (file)
--- 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
index 21ac5ee4b43f3e767b56aff2f54c6018175bc6af..bcb884e2d613e76d94570dd81b99ba27e3906a66 100644 (file)
--- 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