fortify: Add compile-time FORTIFY_SOURCE tests

While the run-time testing of FORTIFY_SOURCE is already present in
LKDTM, there is no testing of the expected compile-time detections. In
preparation for correctly supporting FORTIFY_SOURCE under Clang, adding
additional FORTIFY_SOURCE defenses, and making sure FORTIFY_SOURCE
doesn't silently regress with GCC, introduce a build-time test suite that
checks each expected compile-time failure condition.

As this is relatively backwards from standard build rules in the
sense that a successful test is actually a compile _failure_, create
a wrapper script to check for the correct errors, and wire it up as
a dummy dependency to lib/string.o, collecting the results into a log
file artifact.

Signed-off-by: Kees Cook <keescook@chromium.org>
This commit is contained in:
Kees Cook
2021-04-20 23:22:52 -07:00
parent 3009f891bb
commit be58f71037
22 changed files with 226 additions and 0 deletions

View File

@@ -360,3 +360,36 @@ obj-$(CONFIG_CMDLINE_KUNIT_TEST) += cmdline_kunit.o
obj-$(CONFIG_SLUB_KUNIT_TEST) += slub_kunit.o
obj-$(CONFIG_GENERIC_LIB_DEVMEM_IS_ALLOWED) += devmem_is_allowed.o
# FORTIFY_SOURCE compile-time behavior tests
TEST_FORTIFY_SRCS = $(wildcard $(srctree)/$(src)/test_fortify/*-*.c)
TEST_FORTIFY_LOGS = $(patsubst $(srctree)/$(src)/%.c, %.log, $(TEST_FORTIFY_SRCS))
TEST_FORTIFY_LOG = test_fortify.log
quiet_cmd_test_fortify = TEST $@
cmd_test_fortify = $(CONFIG_SHELL) $(srctree)/scripts/test_fortify.sh \
$< $@ "$(NM)" $(CC) $(c_flags) \
$(call cc-disable-warning,fortify-source)
targets += $(TEST_FORTIFY_LOGS)
clean-files += $(TEST_FORTIFY_LOGS)
clean-files += $(addsuffix .o, $(TEST_FORTIFY_LOGS))
$(obj)/test_fortify/%.log: $(src)/test_fortify/%.c \
$(src)/test_fortify/test_fortify.h \
$(srctree)/include/linux/fortify-string.h \
$(srctree)/scripts/test_fortify.sh \
FORCE
$(call if_changed,test_fortify)
quiet_cmd_gen_fortify_log = GEN $@
cmd_gen_fortify_log = cat </dev/null $(filter-out FORCE,$^) 2>/dev/null > $@ || true
targets += $(TEST_FORTIFY_LOG)
clean-files += $(TEST_FORTIFY_LOG)
$(obj)/$(TEST_FORTIFY_LOG): $(addprefix $(obj)/, $(TEST_FORTIFY_LOGS)) FORCE
$(call if_changed,gen_fortify_log)
# Fake dependency to trigger the fortify tests.
ifeq ($(CONFIG_FORTIFY_SOURCE),y)
$(obj)/string.o: $(obj)/$(TEST_FORTIFY_LOG)
endif