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 --- lib/.gitignore | 2 + lib/Makefile | 33 +++++++++++ lib/test_fortify/read_overflow-memchr.c | 5 ++ lib/test_fortify/read_overflow-memchr_inv.c | 5 ++ lib/test_fortify/read_overflow-memcmp.c | 5 ++ lib/test_fortify/read_overflow-memscan.c | 5 ++ lib/test_fortify/read_overflow2-memcmp.c | 5 ++ lib/test_fortify/read_overflow2-memcpy.c | 5 ++ lib/test_fortify/read_overflow2-memmove.c | 5 ++ lib/test_fortify/test_fortify.h | 35 +++++++++++ lib/test_fortify/write_overflow-memcpy.c | 5 ++ lib/test_fortify/write_overflow-memmove.c | 5 ++ lib/test_fortify/write_overflow-memset.c | 5 ++ lib/test_fortify/write_overflow-strcpy-lit.c | 5 ++ lib/test_fortify/write_overflow-strcpy.c | 5 ++ lib/test_fortify/write_overflow-strlcpy-src.c | 5 ++ lib/test_fortify/write_overflow-strlcpy.c | 5 ++ lib/test_fortify/write_overflow-strncpy-src.c | 5 ++ lib/test_fortify/write_overflow-strncpy.c | 5 ++ lib/test_fortify/write_overflow-strscpy.c | 5 ++ scripts/test_fortify.sh | 59 +++++++++++++++++++ 21 files changed, 214 insertions(+) create mode 100644 lib/test_fortify/read_overflow-memchr.c create mode 100644 lib/test_fortify/read_overflow-memchr_inv.c create mode 100644 lib/test_fortify/read_overflow-memcmp.c create mode 100644 lib/test_fortify/read_overflow-memscan.c create mode 100644 lib/test_fortify/read_overflow2-memcmp.c create mode 100644 lib/test_fortify/read_overflow2-memcpy.c create mode 100644 lib/test_fortify/read_overflow2-memmove.c create mode 100644 lib/test_fortify/test_fortify.h create mode 100644 lib/test_fortify/write_overflow-memcpy.c create mode 100644 lib/test_fortify/write_overflow-memmove.c create mode 100644 lib/test_fortify/write_overflow-memset.c create mode 100644 lib/test_fortify/write_overflow-strcpy-lit.c create mode 100644 lib/test_fortify/write_overflow-strcpy.c create mode 100644 lib/test_fortify/write_overflow-strlcpy-src.c create mode 100644 lib/test_fortify/write_overflow-strlcpy.c create mode 100644 lib/test_fortify/write_overflow-strncpy-src.c create mode 100644 lib/test_fortify/write_overflow-strncpy.c create mode 100644 lib/test_fortify/write_overflow-strscpy.c create mode 100644 scripts/test_fortify.sh
diff --git a/lib/.gitignore b/lib/.gitignore index 5e7fa54c4536..e5e217b8307b 100644 --- a/lib/.gitignore +++ b/lib/.gitignore @@ -4,3 +4,5 @@ /gen_crc32table /gen_crc64table /oid_registry_data.c +/test_fortify.log +/test_fortify/*.log diff --git a/lib/Makefile b/lib/Makefile index 5efd1b435a37..bd17c2bf43e1 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -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 diff --git a/lib/test_fortify/read_overflow-memchr.c b/lib/test_fortify/read_overflow-memchr.c new file mode 100644 index 000000000000..2743084b32af --- /dev/null +++ b/lib/test_fortify/read_overflow-memchr.c @@ -0,0 +1,5 @@ +// SPDX-License-Identifier: GPL-2.0-only +#define TEST \ + memchr(small, 0x7A, sizeof(small) + 1) + +#include "test_fortify.h" diff --git a/lib/test_fortify/read_overflow-memchr_inv.c b/lib/test_fortify/read_overflow-memchr_inv.c new file mode 100644 index 000000000000..b26e1f1bc217 --- /dev/null +++ b/lib/test_fortify/read_overflow-memchr_inv.c @@ -0,0 +1,5 @@ +// SPDX-License-Identifier: GPL-2.0-only +#define TEST \ + memchr_inv(small, 0x7A, sizeof(small) + 1) + +#include "test_fortify.h" diff --git a/lib/test_fortify/read_overflow-memcmp.c b/lib/test_fortify/read_overflow-memcmp.c new file mode 100644 index 000000000000..d5d301ff64ef --- /dev/null +++ b/lib/test_fortify/read_overflow-memcmp.c @@ -0,0 +1,5 @@ +// SPDX-License-Identifier: GPL-2.0-only +#define TEST \ + memcmp(small, large, sizeof(small) + 1) + +#include "test_fortify.h" diff --git a/lib/test_fortify/read_overflow-memscan.c b/lib/test_fortify/read_overflow-memscan.c new file mode 100644 index 000000000000..c1a97f2df0f0 --- /dev/null +++ b/lib/test_fortify/read_overflow-memscan.c @@ -0,0 +1,5 @@ +// SPDX-License-Identifier: GPL-2.0-only +#define TEST \ + memscan(small, 0x7A, sizeof(small) + 1) + +#include "test_fortify.h" diff --git a/lib/test_fortify/read_overflow2-memcmp.c b/lib/test_fortify/read_overflow2-memcmp.c new file mode 100644 index 000000000000..c6091e640f76 --- /dev/null +++ b/lib/test_fortify/read_overflow2-memcmp.c @@ -0,0 +1,5 @@ +// SPDX-License-Identifier: GPL-2.0-only +#define TEST \ + memcmp(large, small, sizeof(small) + 1) + +#include "test_fortify.h" diff --git a/lib/test_fortify/read_overflow2-memcpy.c b/lib/test_fortify/read_overflow2-memcpy.c new file mode 100644 index 000000000000..07b62e56cf16 --- /dev/null +++ b/lib/test_fortify/read_overflow2-memcpy.c @@ -0,0 +1,5 @@ +// SPDX-License-Identifier: GPL-2.0-only +#define TEST \ + memcpy(large, instance.buf, sizeof(large)) + +#include "test_fortify.h" diff --git a/lib/test_fortify/read_overflow2-memmove.c b/lib/test_fortify/read_overflow2-memmove.c new file mode 100644 index 000000000000..34edfab040a3 --- /dev/null +++ b/lib/test_fortify/read_overflow2-memmove.c @@ -0,0 +1,5 @@ +// SPDX-License-Identifier: GPL-2.0-only +#define TEST \ + memmove(large, instance.buf, sizeof(large)) + +#include "test_fortify.h" diff --git a/lib/test_fortify/test_fortify.h b/lib/test_fortify/test_fortify.h new file mode 100644 index 000000000000..e1dfe64d79a3 --- /dev/null +++ b/lib/test_fortify/test_fortify.h @@ -0,0 +1,35 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include <linux/kernel.h> +#include <linux/printk.h> +#include <linux/slab.h> +#include <linux/string.h> + +void do_fortify_tests(void); + +#define __BUF_SMALL 16 +#define __BUF_LARGE 32 +struct fortify_object { + int a; + char buf[__BUF_SMALL]; + int c; +}; + +#define LITERAL_SMALL "AAAAAAAAAAAAAAA" +#define LITERAL_LARGE "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA" +const char small_src[__BUF_SMALL] = LITERAL_SMALL; +const char large_src[__BUF_LARGE] = LITERAL_LARGE; + +char small[__BUF_SMALL]; +char large[__BUF_LARGE]; +struct fortify_object instance; +size_t size; + +void do_fortify_tests(void) +{ + /* Normal initializations. */ + memset(&instance, 0x32, sizeof(instance)); + memset(small, 0xA5, sizeof(small)); + memset(large, 0x5A, sizeof(large)); + + TEST; +} diff --git a/lib/test_fortify/write_overflow-memcpy.c b/lib/test_fortify/write_overflow-memcpy.c new file mode 100644 index 000000000000..3b3984e428fb --- /dev/null +++ b/lib/test_fortify/write_overflow-memcpy.c @@ -0,0 +1,5 @@ +// SPDX-License-Identifier: GPL-2.0-only +#define TEST \ + memcpy(instance.buf, large_src, sizeof(large_src)) + +#include "test_fortify.h" diff --git a/lib/test_fortify/write_overflow-memmove.c b/lib/test_fortify/write_overflow-memmove.c new file mode 100644 index 000000000000..640437c3b3e0 --- /dev/null +++ b/lib/test_fortify/write_overflow-memmove.c @@ -0,0 +1,5 @@ +// SPDX-License-Identifier: GPL-2.0-only +#define TEST \ + memmove(instance.buf, large_src, sizeof(large_src)) + +#include "test_fortify.h" diff --git a/lib/test_fortify/write_overflow-memset.c b/lib/test_fortify/write_overflow-memset.c new file mode 100644 index 000000000000..36e34908cfb3 --- /dev/null +++ b/lib/test_fortify/write_overflow-memset.c @@ -0,0 +1,5 @@ +// SPDX-License-Identifier: GPL-2.0-only +#define TEST \ + memset(instance.buf, 0x5A, sizeof(large_src)) + +#include "test_fortify.h" diff --git a/lib/test_fortify/write_overflow-strcpy-lit.c b/lib/test_fortify/write_overflow-strcpy-lit.c new file mode 100644 index 000000000000..51effb3e50f9 --- /dev/null +++ b/lib/test_fortify/write_overflow-strcpy-lit.c @@ -0,0 +1,5 @@ +// SPDX-License-Identifier: GPL-2.0-only +#define TEST \ + strcpy(small, LITERAL_LARGE) + +#include "test_fortify.h" diff --git a/lib/test_fortify/write_overflow-strcpy.c b/lib/test_fortify/write_overflow-strcpy.c new file mode 100644 index 000000000000..84f1c56a64c8 --- /dev/null +++ b/lib/test_fortify/write_overflow-strcpy.c @@ -0,0 +1,5 @@ +// SPDX-License-Identifier: GPL-2.0-only +#define TEST \ + strcpy(small, large_src) + +#include "test_fortify.h" diff --git a/lib/test_fortify/write_overflow-strlcpy-src.c b/lib/test_fortify/write_overflow-strlcpy-src.c new file mode 100644 index 000000000000..91bf83ebd34a --- /dev/null +++ b/lib/test_fortify/write_overflow-strlcpy-src.c @@ -0,0 +1,5 @@ +// SPDX-License-Identifier: GPL-2.0-only +#define TEST \ + strlcpy(small, large_src, sizeof(small) + 1) + +#include "test_fortify.h" diff --git a/lib/test_fortify/write_overflow-strlcpy.c b/lib/test_fortify/write_overflow-strlcpy.c new file mode 100644 index 000000000000..1883db7c0cd6 --- /dev/null +++ b/lib/test_fortify/write_overflow-strlcpy.c @@ -0,0 +1,5 @@ +// SPDX-License-Identifier: GPL-2.0-only +#define TEST \ + strlcpy(instance.buf, large_src, sizeof(instance.buf) + 1) + +#include "test_fortify.h" diff --git a/lib/test_fortify/write_overflow-strncpy-src.c b/lib/test_fortify/write_overflow-strncpy-src.c new file mode 100644 index 000000000000..8dcfb8c788dd --- /dev/null +++ b/lib/test_fortify/write_overflow-strncpy-src.c @@ -0,0 +1,5 @@ +// SPDX-License-Identifier: GPL-2.0-only +#define TEST \ + strncpy(small, large_src, sizeof(small) + 1) + +#include "test_fortify.h" diff --git a/lib/test_fortify/write_overflow-strncpy.c b/lib/test_fortify/write_overflow-strncpy.c new file mode 100644 index 000000000000..b85f079c815d --- /dev/null +++ b/lib/test_fortify/write_overflow-strncpy.c @@ -0,0 +1,5 @@ +// SPDX-License-Identifier: GPL-2.0-only +#define TEST \ + strncpy(instance.buf, large_src, sizeof(instance.buf) + 1) + +#include "test_fortify.h" diff --git a/lib/test_fortify/write_overflow-strscpy.c b/lib/test_fortify/write_overflow-strscpy.c new file mode 100644 index 000000000000..38feddf377dc --- /dev/null +++ b/lib/test_fortify/write_overflow-strscpy.c @@ -0,0 +1,5 @@ +// SPDX-License-Identifier: GPL-2.0-only +#define TEST \ + strscpy(instance.buf, large_src, sizeof(instance.buf) + 1) + +#include "test_fortify.h" diff --git a/scripts/test_fortify.sh b/scripts/test_fortify.sh new file mode 100644 index 000000000000..a6d63871738b --- /dev/null +++ b/scripts/test_fortify.sh @@ -0,0 +1,59 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0-only +set -e + +# Argument 1: Source file to build. +IN="$1" +shift +# Extract just the filename for error messages below. +FILE="${IN##*/}" +# Extract the function name for error messages below. +FUNC="${FILE#*-}" +FUNC="${FUNC%%-*}" +FUNC="${FUNC%%.*}" +# Extract the symbol to test for in build/symbol test below. +WANT="__${FILE%%-*}" + +# Argument 2: Where to write the build log. +OUT="$1" +shift +TMP="${OUT}.tmp" + +# Argument 3: Path to "nm" tool. +NM="$1" +shift + +# Remaining arguments are: $(CC) $(c_flags) + +# Clean up temporary file at exit. +__cleanup() { + rm -f "$TMP" +} +trap __cleanup EXIT + +status= +# Attempt to build a source that is expected to fail with a specific warning. +if "$@" -Werror -c "$IN" -o "$OUT".o 2> "$TMP" ; then + # If the build succeeds, either the test has failed or the the + # warning may only happen at link time (Clang). In that case, + # make sure the expected symbol is unresolved in the symbol list. + # If so, FORTIFY is working for this case. + if ! $NM -A "$OUT".o | grep -m1 "\bU ${WANT}$" >>"$TMP" ; then + status="warning: unsafe ${FUNC}() usage lacked '$WANT' symbol in $IN" + fi +else + # If the build failed, check for the warning in the stderr (gcc). + if ! grep -q -m1 "error:.*\b${WANT}'" "$TMP" ; then + status="warning: unsafe ${FUNC}() usage lacked '$WANT' warning in $IN" + fi +fi + +if [ -n "$status" ]; then + # Report on failure results, including compilation warnings. + echo "$status" | tee "$OUT" >&2 + cat "$TMP" | tee -a "$OUT" >&2 +else + # Report on good results, and save any compilation output to log. + echo "ok: unsafe ${FUNC}() usage correctly detected with '$WANT' in $IN" >"$OUT" + cat "$TMP" >>"$OUT" +fi