rnsl

commit cc551d9d0b836e3137e451938e80e4fb5c06ef20
parent fa57a9f9463e3bd17c96410ba64a286e641781f0
Author: Vincent Forest <vincent.forest@meso-star.com>
Date:   Tue, 31 Oct 2023 11:36:03 +0100

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:
M
Makefile
 | 
16
+++++++---------
M
config.mk
 | 
21
++++++++++++++++-----

2 files changed, 23 insertions(+), 14 deletions(-)
diff --git a/Makefile b/Makefile
@@ -47,7 +47,7 @@ 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): librnsl.o
 	$(AR) -rc $@ $?
@@ -64,10 +64,10 @@ librnsl.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) -DRNSL_SHARED_BUILD -c $< -o $@
+	$(CC) $(CFLAGS_SO) $(RSYS_CFLAGS) -DRNSL_SHARED_BUILD -c $< -o $@
 
 ################################################################################
 # Installation
@@ -143,13 +143,11 @@ clean_test:
 	$(SHELL) make.sh clean_test $(TEST_SRC) file.txt
 
 $(TEST_DEP): config.mk rnsl-local.pc
-	@$(CC) $(CFLAGS) $(RSYS_CFLAGS) $(RNSL_CFLAGS) \
+	@$(CC) $(CFLAGS_EXE) $(RSYS_CFLAGS) $(RNSL_CFLAGS) \
 	-MM -MT "$(@:.d=.o) $@" $(@:.d=.c) -MF $@
 
 $(TEST_OBJ): config.mk rnsl-local.pc
-	$(CC) $(CFLAGS) $(RSYS_CFLAGS) $(RNSL_CFLAGS) -c $(@:.o=.c) -o $@
+	$(CC) $(CFLAGS_EXE) $(RSYS_CFLAGS) $(RNSL_CFLAGS) -c $(@:.o=.c) -o $@
 
-test_rnsl \
-test_rnsl_load \
-: config.mk rnsl-local.pc
-	$(CC) -o $@ src/$@.o $(RSYS_LIBS) $(RNSL_LIBS)
+test_rnsl test_rnsl_load: config.mk rnsl-local.pc
+	$(CC) $(CFLAGS_EXE) -o $@ src/$@.o $(LDFLAGS_EXE) $(RSYS_LIBS) $(RNSL_LIBS)
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 = $(CFLAGS_$(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))