commit ef6ccea88981825b96477b49957acbf42ceee767
parent 6f68ea147c8f99fc481b167d0e0c555c6dcac90e
Author: Vincent Forest <vincent.forest@meso-star.com>
Date: Fri, 27 Oct 2023 16:14:29 +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, 24 insertions(+), 13 deletions(-)
diff --git a/Makefile b/Makefile
@@ -40,7 +40,7 @@ build_library: .config $(DEP)
$(DEP) $(OBJ): config.mk
$(LIBNAME_SHARED): $(OBJ)
- $(CC) $(CFLAGS) $(RSYS_CFLAGS) -o $@ $(OBJ) $(LDFLAGS) $(SOFLAGS) $(RSYS_LIBS)
+ $(CC) $(CFLAGS_SO) $(RSYS_CFLAGS) -o $@ $(OBJ) $(LDFLAGS_SO) $(RSYS_LIBS)
$(LIBNAME_STATIC): libscmap.o
$(AR) -rc $@ $?
@@ -57,10 +57,10 @@ libscmap.o: $(OBJ)
.SUFFIXES: .c .d .o
.c.d:
- @$(CC) $(CFLAGS) $(RSYS_CFLAGS) -MM -MT "$(@:.d=.o) $@" $< -MF $@
+ @$(CC) $(CFLAGS_SO) $(RSYS_CFLAGS) -MM -MT "$(@:.d=.o) $@" $< -MF $@
.c.o:
- $(CC) $(CFLAGS) $(RSYS_CFLAGS) -DSCMAP_SHARED_BUILD -c $< -o $@
+ $(CC) $(CFLAGS_SO) $(RSYS_CFLAGS) -DSCMAP_SHARED_BUILD -c $< -o $@
################################################################################
# Installation
@@ -189,14 +189,14 @@ clean_test:
while read -r i; do rm -f "$${i}.ppm"; done
$(TEST_DEP): config.mk scmap-local.pc
- @$(CC) $(CFLAGS) $(RSYS_CFLAGS) $(SCMAP_CFLAGS) \
+ @$(CC) $(CFLAGS_EXE) $(RSYS_CFLAGS) $(SCMAP_CFLAGS) \
-MM -MT "$(@:.d=.o) $@" $(@:.d=.c) -MF $@
$(TEST_OBJ): config.mk scmap-local.pc
- $(CC) $(CFLAGS) $(RSYS_CFLAGS) $(SCMAP_CFLAGS) -c $(@:.o=.c) -o $@
+ $(CC) $(CFLAGS_EXE) $(RSYS_CFLAGS) $(SCMAP_CFLAGS) -c $(@:.o=.c) -o $@
test_scmap test_scmap_palettes: config.mk scmap-local.pc
- $(CC) -o $@ src/$@.o $(SCMAP_LIBS) $(RSYS_LIBS)
+ $(CC) $(CFLAGS_EXE) -o $@ src/$@.o $(LDFLAGS_EXE) $(SCMAP_LIBS) $(RSYS_LIBS)
test_scmap_fetch_color: config.mk scmap-local.pc
- $(CC) -o $@ src/$@.o $(SCMAP_LIBS) $(RSYS_LIBS) -lm
+ $(CC) $(CFLAGS_EXE) -o $@ src/$@.o $(LDFLAGS_EXE) $(SCMAP_LIBS) $(RSYS_LIBS) -lm
diff --git a/config.mk b/config.mk
@@ -40,27 +40,38 @@ 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_RELEASE = -O2 -DNDEBUG $(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))
