From 19cbac7d264dfca1f75849de64beb98830fbb1e4 Mon Sep 17 00:00:00 2001 From: Hauke Mehrtens Date: Sun, 27 Oct 2019 14:37:45 +0100 Subject: [PATCH] buildsystem: Make PIE ASLR option tristate MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit This tristate choose allows to select to build only some applications with PIE enabled. On MIPS binaries are getting about 30% bigger when PIE is activated for the, which is a huge increase. Network exposed applications like dnsmasq should then be build with PIE enabled, but some applications which are normally not parsing data from the network do not have it activated. The regular option should give a good trade off between extra flash and RAM memory usage and security. This changes the default from building no applications with PIE to build some specifically marked applications with PIE enabled. This option is only activated for targets with bigger flash and RAM to not consume extra memory on the very small targets. On SDK builds the Regular option should always be selected, because some tiny targets share the applications with big targets and only the images for the tiny targets should contain the none PIE applications, but the images for the normal targets should use PIE. The shared packages should always use PIE when it should be normally activated. Signed-off-by: Hauke Mehrtens Acked-by: Petr Å tetiar --- config/Config-build.in | 22 ++++++++++++++++++---- include/hardening.mk | 9 ++++++++- 2 files changed, 26 insertions(+), 5 deletions(-) diff --git a/config/Config-build.in b/config/Config-build.in index c0e4d869f873..59dfaea8bb9b 100644 --- a/config/Config-build.in +++ b/config/Config-build.in @@ -216,11 +216,10 @@ menu "Global build settings" this per package by adding PKG_CHECK_FORMAT_SECURITY:=0 in the package Makefile. - config PKG_ASLR_PIE - bool + choice prompt "User space ASLR PIE compilation" - select BUSYBOX_DEFAULT_PIE - default n + default PKG_ASLR_PIE_NONE if ((SMALL_FLASH || LOW_MEMORY_FOOTPRINT) && !SDK) + default PKG_ASLR_PIE_REGULAR help Add -fPIC to CFLAGS and -specs=hardened-build-ld to LDFLAGS. This enables package build as Position Independent Executables (PIE) @@ -231,6 +230,21 @@ menu "Global build settings" to predict when an attacker is attempting a memory-corruption exploit. You can disable this per package by adding PKG_ASLR_PIE:=0 in the package Makefile. + Be ware that ASLR increases the binary size. + config PKG_ASLR_PIE_NONE + bool "None" + help + PIE is deactivated for all applications + config PKG_ASLR_PIE_REGULAR + bool "Regular" + help + PIE is activated for some binaries, mostly network exposed applications + config PKG_ASLR_PIE_ALL + bool "All" + select BUSYBOX_DEFAULT_PIE + help + PIE is activated for all applications + endchoice choice prompt "User space Stack-Smashing Protection" diff --git a/include/hardening.mk b/include/hardening.mk index 60f39428e83e..4e49e6b1b904 100644 --- a/include/hardening.mk +++ b/include/hardening.mk @@ -7,6 +7,7 @@ PKG_CHECK_FORMAT_SECURITY ?= 1 PKG_ASLR_PIE ?= 1 +PKG_ASLR_PIE_REGULAR ?= 0 PKG_SSP ?= 1 PKG_FORTIFY_SOURCE ?= 1 PKG_RELRO ?= 1 @@ -16,12 +17,18 @@ ifdef CONFIG_PKG_CHECK_FORMAT_SECURITY TARGET_CFLAGS += -Wformat -Werror=format-security endif endif -ifdef CONFIG_PKG_ASLR_PIE +ifdef CONFIG_PKG_ASLR_PIE_ALL ifeq ($(strip $(PKG_ASLR_PIE)),1) TARGET_CFLAGS += $(FPIC) TARGET_LDFLAGS += $(FPIC) -specs=$(INCLUDE_DIR)/hardened-ld-pie.specs endif endif +ifdef CONFIG_PKG_ASLR_PIE_REGULAR + ifeq ($(strip $(PKG_ASLR_PIE_REGULAR)),1) + TARGET_CFLAGS += $(FPIC) + TARGET_LDFLAGS += $(FPIC) -specs=$(INCLUDE_DIR)/hardened-ld-pie.specs + endif +endif ifdef CONFIG_PKG_CC_STACKPROTECTOR_REGULAR ifeq ($(strip $(PKG_SSP)),1) TARGET_CFLAGS += -fstack-protector -- 2.30.2