commit 6c8b0c06c5306fad8f970656ab109cafee888ccc
parent 247793d0b14b3a4fb82f6ae056d3324b44710f48
Author: Vincent Forest <vincent.forest@meso-star.com>
Date: Wed, 18 Oct 2023 14:25:04 +0200
Make generated binaries safer and more robust
Define the CFLAGS_HARDENED and LDFLAGS_HARDENED macros, which list
compiler and linker options that activate various hardening features
aimed at increasing the security and robustness of generated binaries.
The link editor options have all been available since at least ld 2.25.
So you don't have to worry about compatibility issues.
The compiler options are in fact some of those that will be enabled by
the -fhardened option to be introduced in GCC 14. In the following, we
list them and indicate the version of GCC from which they are documented
in the manual, i.e. from which version of GCC they would appear to be
available:
-D_FORTIFY_SOURCE [GCC 5.5]
-fcf-protection options [GCC 8.5]
-fstack-protector-strong [GCC 6.5]
-fstack-clash-protection [GCC 8.5]
-ftrivial-auto-var-init [GCC 12.3]
The latter, -ftrivial-auto-var-init, is too recent. To avoid any
compatibility problems, we haven't activated it yet.
Diffstat:
2 files changed, 22 insertions(+), 11 deletions(-)
diff --git a/Makefile b/Makefile
@@ -40,7 +40,7 @@ build_library: .config $(DEP)
$(DEP) $(OBJ): config.mk
$(LIBNAME_SHARED): $(OBJ)
- $(CC) $(CFLAGS) $(DPDC_CFLAGS) -o $@ $(OBJ) $(LDFLAGS) $(SOFLAGS) $(DPDC_LIBS)
+ $(CC) $(CFLAGS_SO) $(DPDC_CFLAGS) -o $@ $(OBJ) $(LDFLAGS_SO) $(DPDC_LIBS)
$(LIBNAME_STATIC): libpolygon.o
$(AR) -rc $@ $?
@@ -57,10 +57,10 @@ libpolygon.o: $(OBJ)
.SUFFIXES: .c .d .o
.c.d:
- @$(CC) $(CFLAGS) $(DPDC_CFLAGS) -MM -MT "$(@:.d=.o) $@" $< -MF $@
+ @$(CC) $(CFLAGS_SO) $(DPDC_CFLAGS) -MM -MT "$(@:.d=.o) $@" $< -MF $@
.c.o:
- $(CC) $(CFLAGS) $(DPDC_CFLAGS) -DPOLYGON_SHARED_BUILD -c $< -o $@
+ $(CC) $(CFLAGS_SO) $(DPDC_CFLAGS) -DPOLYGON_SHARED_BUILD -c $< -o $@
################################################################################
# Installation
@@ -135,10 +135,11 @@ clean_test:
$(TEST_DEP) $(TEST_OBJ): config.mk polygon-local.pc
$(TEST_DEP):
- @$(CC) $(CFLAGS) $(POLYGON_CFLAGS) $(RSYS_CFLAGS) -MM -MT "$(@:.d=.o) $@" $(@:.d=.c) -MF $@
+ @$(CC) $(CFLAGS_EXE) $(POLYGON_CFLAGS) $(RSYS_CFLAGS) \
+ -MM -MT "$(@:.d=.o) $@" $(@:.d=.c) -MF $@
$(TEST_OBJ): config.mk polygon-local.pc
- $(CC) $(CFLAGS) $(POLYGON_CFLAGS) $(RSYS_CFLAGS) -c $(@:.o=.c) -o $@
+ $(CC) $(CFLAGS_EXE) $(POLYGON_CFLAGS) $(RSYS_CFLAGS) -c $(@:.o=.c) -o $@
test_polygon test_polygon1: config.mk polygon-local.pc
- $(CC) -o $@ src/$@.o $(LDFLAGS) $(POLYGON_LIBS) $(RSYS_LIBS) -lm
+ $(CC) $(CFLAGS_EXE) -o $@ src/$@.o $(LDFLAGS_EXE) $(POLYGON_LIBS) $(RSYS_LIBS) -lm
diff --git a/config.mk b/config.mk
@@ -42,27 +42,37 @@ WFLAGS =\
-Wmissing-prototypes\
-Wshadow
+CFLAGS_HARDENED =\
+ -D_FORTIFY_SOURCES=2\
+ -fcf-protection=full\
+ -fstack-clash-protection\
+ -fstack-protector-strong
+
CFLAGS_COMMON =\
-std=c89\
-pedantic\
- -fPIC\
-fvisibility=hidden\
-fstrict-aliasing\
+ $(CFLAGS_HARDENED)\
$(WFLAGS)
CFLAGS_RELEASE = -O2 -DNDEBUG $(CFLAGS_COMMON)
CFLAGS_DEBUG = -g $(CFLAGS_COMMON)
CFLAGS = $(CFLAGS_$(BUILD_TYPE))
+CFLAGS_SO = $(CFLAGS) -fPIC
+CFLAGS_EXE = $(CFLAGS) -fPIE
################################################################################
# Linker options
################################################################################
-SOFLAGS = -shared -Wl,--no-undefined
-
-LDFLAGS_DEBUG =
-LDFLAGS_RELEASE = -s
+LDFLAGS_HARDENED = -Wl,-z,relro,-z,now
+LDFLAGS_DEBUG = $(LDFLAGS_HARDENED)
+LDFLAGS_RELEASE = -s $(LDFLAGS_HARDENED)
LDFLAGS = $(LDFLAGS_$(BUILD_TYPE))
+LDFLAGS_SO = $(LDFLAGS) -shared -Wl,--no-undefined
+LDFLAGS_EXE = $(LDFLAGS) -pie
+
OCPFLAGS_DEBUG = --localize-hidden
OCPFLAGS_RELEASE = --localize-hidden --strip-unneeded
OCPFLAGS = $(OCPFLAGS_$(BUILD_TYPE))
