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buildsystem: Make PIE ASLR option tristate 

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 <hauke@hauke-m.de>
Acked-by: Petr Štetiar <ynezz@true.cz>
master
Hauke Mehrtens 2019-10-27 14:37:45 +01:00 committed by Petr Štetiar
parent 3446702cdb
commit 19cbac7d26
2 changed files with 26 additions and 5 deletions
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22
config/Config-build.in
View File

@ -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"

9
include/hardening.mk
View File

@ -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