[PATCH 0/3] selftests: openat2: migrate to kselftests harness

[PATCH 0/3] selftests: openat2: migrate to kselftests harness

[Aleksa Sarai]

These tests were written in the early days of selftests' TAP support,
the more modern kselftest harness is much easier to follow and maintain.
The actual contents of the tests are unchanged by this change.

Signed-off-by: Aleksa Sarai <aleksa@amutable.com>
---
Aleksa Sarai (3):
      selftests: openat2: move helpers to header
      selftests: openat2: switch from custom ARRAY_LEN to ARRAY_SIZE
      selftests: openat2: migrate to kselftest harness

 tools/testing/selftests/openat2/Makefile           |   2 -
 tools/testing/selftests/openat2/helpers.c          | 109 ------
 tools/testing/selftests/openat2/helpers.h          | 164 ++++++---
 tools/testing/selftests/openat2/openat2_test.c     | 223 ++++++-------
 .../testing/selftests/openat2/rename_attack_test.c | 161 +++++----
 tools/testing/selftests/openat2/resolve_test.c     | 368 ++++++++++++---------
 6 files changed, 494 insertions(+), 533 deletions(-)
---
base-commit: 5e4e16d498eccca363db526433803932921dd74f
change-id: 20260317-openat2-selftests-kunit-6939af23ee27


Kind regards,
-- 
Aleksa Sarai
https://www.cyphar.com/

[PATCH 1/3] selftests: openat2: move helpers to header

[Aleksa Sarai]

This is a bit ugly, but in the next patch we will move to using
kselftest_harness.h -- which doesn't play well with being included in
multiple compilation units due to duplicate function definitions.

Not including kselftest_harness.h would let us avoid this patch, but the
helpers will need include kselftest_harness.h in order to switch to
TH_LOG.

Signed-off-by: Aleksa Sarai <aleksa@amutable.com>
---
 tools/testing/selftests/openat2/Makefile  |   2 -
 tools/testing/selftests/openat2/helpers.c | 109 --------------------------
 tools/testing/selftests/openat2/helpers.h | 125 +++++++++++++++++++++++++-----
 3 files changed, 107 insertions(+), 129 deletions(-)

diff --git a/tools/testing/selftests/openat2/Makefile b/tools/testing/selftests/openat2/Makefile
index 185dc76ebb5f..3100b4d8d1b2 100644
--- a/tools/testing/selftests/openat2/Makefile
+++ b/tools/testing/selftests/openat2/Makefile
@@ -14,5 +14,3 @@ endif
 LOCAL_HDRS += helpers.h
 
 include ../lib.mk
-
-$(TEST_GEN_PROGS): helpers.c
diff --git a/tools/testing/selftests/openat2/helpers.c b/tools/testing/selftests/openat2/helpers.c
deleted file mode 100644
index 5074681ffdc9..000000000000
--- a/tools/testing/selftests/openat2/helpers.c
+++ /dev/null
@@ -1,109 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
-/*
- * Author: Aleksa Sarai <cyphar@cyphar.com>
- * Copyright (C) 2018-2019 SUSE LLC.
- */
-
-#define _GNU_SOURCE
-#include <errno.h>
-#include <fcntl.h>
-#include <stdbool.h>
-#include <string.h>
-#include <syscall.h>
-#include <limits.h>
-
-#include "helpers.h"
-
-bool needs_openat2(const struct open_how *how)
-{
-	return how->resolve != 0;
-}
-
-int raw_openat2(int dfd, const char *path, void *how, size_t size)
-{
-	int ret = syscall(__NR_openat2, dfd, path, how, size);
-	return ret >= 0 ? ret : -errno;
-}
-
-int sys_openat2(int dfd, const char *path, struct open_how *how)
-{
-	return raw_openat2(dfd, path, how, sizeof(*how));
-}
-
-int sys_openat(int dfd, const char *path, struct open_how *how)
-{
-	int ret = openat(dfd, path, how->flags, how->mode);
-	return ret >= 0 ? ret : -errno;
-}
-
-int sys_renameat2(int olddirfd, const char *oldpath,
-		  int newdirfd, const char *newpath, unsigned int flags)
-{
-	int ret = syscall(__NR_renameat2, olddirfd, oldpath,
-					  newdirfd, newpath, flags);
-	return ret >= 0 ? ret : -errno;
-}
-
-int touchat(int dfd, const char *path)
-{
-	int fd = openat(dfd, path, O_CREAT, 0700);
-	if (fd >= 0)
-		close(fd);
-	return fd;
-}
-
-char *fdreadlink(int fd)
-{
-	char *target, *tmp;
-
-	E_asprintf(&tmp, "/proc/self/fd/%d", fd);
-
-	target = malloc(PATH_MAX);
-	if (!target)
-		ksft_exit_fail_msg("fdreadlink: malloc failed\n");
-	memset(target, 0, PATH_MAX);
-
-	E_readlink(tmp, target, PATH_MAX);
-	free(tmp);
-	return target;
-}
-
-bool fdequal(int fd, int dfd, const char *path)
-{
-	char *fdpath, *dfdpath, *other;
-	bool cmp;
-
-	fdpath = fdreadlink(fd);
-	dfdpath = fdreadlink(dfd);
-
-	if (!path)
-		E_asprintf(&other, "%s", dfdpath);
-	else if (*path == '/')
-		E_asprintf(&other, "%s", path);
-	else
-		E_asprintf(&other, "%s/%s", dfdpath, path);
-
-	cmp = !strcmp(fdpath, other);
-
-	free(fdpath);
-	free(dfdpath);
-	free(other);
-	return cmp;
-}
-
-bool openat2_supported = false;
-
-void __attribute__((constructor)) init(void)
-{
-	struct open_how how = {};
-	int fd;
-
-	BUILD_BUG_ON(sizeof(struct open_how) != OPEN_HOW_SIZE_VER0);
-
-	/* Check openat2(2) support. */
-	fd = sys_openat2(AT_FDCWD, ".", &how);
-	openat2_supported = (fd >= 0);
-
-	if (fd >= 0)
-		close(fd);
-}
diff --git a/tools/testing/selftests/openat2/helpers.h b/tools/testing/selftests/openat2/helpers.h
index 510e60602511..975de513af86 100644
--- a/tools/testing/selftests/openat2/helpers.h
+++ b/tools/testing/selftests/openat2/helpers.h
@@ -2,6 +2,7 @@
 /*
  * Author: Aleksa Sarai <cyphar@cyphar.com>
  * Copyright (C) 2018-2019 SUSE LLC.
+ * Copyright (C) 2026 Amutable GmbH
  */
 
 #ifndef __RESOLVEAT_H__
@@ -11,19 +12,14 @@
 #include <stdint.h>
 #include <stdbool.h>
 #include <errno.h>
+#include <limits.h>
 #include <linux/types.h>
+#include <linux/unistd.h>
 #include "kselftest.h"
 
 #define ARRAY_LEN(X) (sizeof (X) / sizeof (*(X)))
 #define BUILD_BUG_ON(e) ((void)(sizeof(struct { int:(-!!(e)); })))
 
-#ifndef SYS_openat2
-#ifndef __NR_openat2
-#define __NR_openat2 437
-#endif /* __NR_openat2 */
-#define SYS_openat2 __NR_openat2
-#endif /* SYS_openat2 */
-
 /*
  * Arguments for how openat2(2) should open the target path. If @resolve is
  * zero, then openat2(2) operates very similarly to openat(2).
@@ -45,8 +41,6 @@ struct open_how {
 #define OPEN_HOW_SIZE_VER0	24 /* sizeof first published struct */
 #define OPEN_HOW_SIZE_LATEST	OPEN_HOW_SIZE_VER0
 
-bool needs_openat2(const struct open_how *how);
-
 #ifndef RESOLVE_IN_ROOT
 /* how->resolve flags for openat2(2). */
 #define RESOLVE_NO_XDEV		0x01 /* Block mount-point crossings
@@ -93,16 +87,111 @@ bool needs_openat2(const struct open_how *how);
 					   __FILE__, __LINE__, #expr, ##__VA_ARGS__); \
 	} while (0)
 
-int raw_openat2(int dfd, const char *path, void *how, size_t size);
-int sys_openat2(int dfd, const char *path, struct open_how *how);
-int sys_openat(int dfd, const char *path, struct open_how *how);
-int sys_renameat2(int olddirfd, const char *oldpath,
-		  int newdirfd, const char *newpath, unsigned int flags);
+__maybe_unused
+static bool needs_openat2(const struct open_how *how)
+{
+	return how->resolve != 0;
+}
+
+__maybe_unused
+static int raw_openat2(int dfd, const char *path, void *how, size_t size)
+{
+	int ret = syscall(__NR_openat2, dfd, path, how, size);
+
+	return ret >= 0 ? ret : -errno;
+}
+
+__maybe_unused
+static int sys_openat2(int dfd, const char *path, struct open_how *how)
+{
+	return raw_openat2(dfd, path, how, sizeof(*how));
+}
+
+__maybe_unused
+static int sys_openat(int dfd, const char *path, struct open_how *how)
+{
+	int ret = openat(dfd, path, how->flags, how->mode);
+
+	return ret >= 0 ? ret : -errno;
+}
+
+__maybe_unused
+static int sys_renameat2(int olddirfd, const char *oldpath,
+			 int newdirfd, const char *newpath, unsigned int flags)
+{
+	int ret = syscall(__NR_renameat2, olddirfd, oldpath,
+					  newdirfd, newpath, flags);
+
+	return ret >= 0 ? ret : -errno;
+}
+
+__maybe_unused
+static int touchat(int dfd, const char *path)
+{
+	int fd = openat(dfd, path, O_CREAT, 0700);
+
+	if (fd >= 0)
+		close(fd);
+	return fd;
+}
+
+__maybe_unused
+static char *fdreadlink(int fd)
+{
+	char *target, *tmp;
+
+	E_asprintf(&tmp, "/proc/self/fd/%d", fd);
+
+	target = malloc(PATH_MAX);
+	if (!target)
+		ksft_exit_fail_msg("fdreadlink: malloc failed\n");
+	memset(target, 0, PATH_MAX);
+
+	E_readlink(tmp, target, PATH_MAX);
+	free(tmp);
+	return target;
+}
+
+__maybe_unused
+static bool fdequal(int fd, int dfd, const char *path)
+{
+	char *fdpath, *dfdpath, *other;
+	bool cmp;
+
+	fdpath = fdreadlink(fd);
+	dfdpath = fdreadlink(dfd);
+
+	if (!path)
+		E_asprintf(&other, "%s", dfdpath);
+	else if (*path == '/')
+		E_asprintf(&other, "%s", path);
+	else
+		E_asprintf(&other, "%s/%s", dfdpath, path);
+
+	cmp = !strcmp(fdpath, other);
+
+	free(fdpath);
+	free(dfdpath);
+	free(other);
+	return cmp;
+}
+
+static bool openat2_supported = false;
+
+__attribute__((constructor))
+static void __detect_openat2_supported(void)
+{
+	struct open_how how = {};
+	int fd;
+
+	BUILD_BUG_ON(sizeof(struct open_how) != OPEN_HOW_SIZE_VER0);
 
-int touchat(int dfd, const char *path);
-char *fdreadlink(int fd);
-bool fdequal(int fd, int dfd, const char *path);
+	/* Check openat2(2) support. */
+	fd = sys_openat2(AT_FDCWD, ".", &how);
+	openat2_supported = (fd >= 0);
 
-extern bool openat2_supported;
+	if (fd >= 0)
+		close(fd);
+}
 
 #endif /* __RESOLVEAT_H__ */

-- 
2.53.0

[PATCH 2/3] selftests: openat2: switch from custom ARRAY_LEN to ARRAY_SIZE

[Aleksa Sarai]

For whatever reason, the original version of the tests used a custom
version of ARRAY_SIZE, but ARRAY_SIZE works just as well.

Signed-off-by: Aleksa Sarai <aleksa@amutable.com>
---
 tools/testing/selftests/openat2/helpers.h      |  1 -
 tools/testing/selftests/openat2/openat2_test.c | 12 ++++++------
 tools/testing/selftests/openat2/resolve_test.c |  4 ++--
 3 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/tools/testing/selftests/openat2/helpers.h b/tools/testing/selftests/openat2/helpers.h
index 975de513af86..f56c0c6e3ad1 100644
--- a/tools/testing/selftests/openat2/helpers.h
+++ b/tools/testing/selftests/openat2/helpers.h
@@ -17,7 +17,6 @@
 #include <linux/unistd.h>
 #include "kselftest.h"
 
-#define ARRAY_LEN(X) (sizeof (X) / sizeof (*(X)))
 #define BUILD_BUG_ON(e) ((void)(sizeof(struct { int:(-!!(e)); })))
 
 /*
diff --git a/tools/testing/selftests/openat2/openat2_test.c b/tools/testing/selftests/openat2/openat2_test.c
index 0e161ef9e9e4..c6c26652ac1b 100644
--- a/tools/testing/selftests/openat2/openat2_test.c
+++ b/tools/testing/selftests/openat2/openat2_test.c
@@ -83,14 +83,14 @@ void test_openat2_struct(void)
 		  .size = sizeof(struct open_how_ext), .err = -E2BIG },
 	};
 
-	BUILD_BUG_ON(ARRAY_LEN(misalignments) != NUM_OPENAT2_STRUCT_VARIATIONS);
-	BUILD_BUG_ON(ARRAY_LEN(tests) != NUM_OPENAT2_STRUCT_TESTS);
+	BUILD_BUG_ON(ARRAY_SIZE(misalignments) != NUM_OPENAT2_STRUCT_VARIATIONS);
+	BUILD_BUG_ON(ARRAY_SIZE(tests) != NUM_OPENAT2_STRUCT_TESTS);
 
-	for (int i = 0; i < ARRAY_LEN(tests); i++) {
+	for (int i = 0; i < ARRAY_SIZE(tests); i++) {
 		struct struct_test *test = &tests[i];
 		struct open_how_ext how_ext = test->arg;
 
-		for (int j = 0; j < ARRAY_LEN(misalignments); j++) {
+		for (int j = 0; j < ARRAY_SIZE(misalignments); j++) {
 			int fd, misalign = misalignments[j];
 			char *fdpath = NULL;
 			bool failed;
@@ -241,9 +241,9 @@ void test_openat2_flags(void)
 		  .how.resolve = 0, .err = -EINVAL },
 	};
 
-	BUILD_BUG_ON(ARRAY_LEN(tests) != NUM_OPENAT2_FLAG_TESTS);
+	BUILD_BUG_ON(ARRAY_SIZE(tests) != NUM_OPENAT2_FLAG_TESTS);
 
-	for (int i = 0; i < ARRAY_LEN(tests); i++) {
+	for (int i = 0; i < ARRAY_SIZE(tests); i++) {
 		int fd, fdflags = -1;
 		char *path, *fdpath = NULL;
 		bool failed = false;
diff --git a/tools/testing/selftests/openat2/resolve_test.c b/tools/testing/selftests/openat2/resolve_test.c
index a76ef15ceb90..f7acb4300641 100644
--- a/tools/testing/selftests/openat2/resolve_test.c
+++ b/tools/testing/selftests/openat2/resolve_test.c
@@ -436,9 +436,9 @@ void test_openat2_opath_tests(void)
 		  .out.err = -ELOOP,		.pass = false },
 	};
 
-	BUILD_BUG_ON(ARRAY_LEN(tests) != NUM_OPENAT2_OPATH_TESTS);
+	BUILD_BUG_ON(ARRAY_SIZE(tests) != NUM_OPENAT2_OPATH_TESTS);
 
-	for (int i = 0; i < ARRAY_LEN(tests); i++) {
+	for (int i = 0; i < ARRAY_SIZE(tests); i++) {
 		int dfd, fd;
 		char *fdpath = NULL;
 		bool failed;

-- 
2.53.0

[PATCH 3/3] selftests: openat2: migrate to kselftest harness

[Aleksa Sarai]

These tests were written in the early days of selftests' TAP support,
the more modern kselftest harness is much easier to follow and maintain.
The actual contents of the tests are unchanged by this change. Most of
the diff involves switching from the E_* syscall wrappers we previously
used to ASSERT_EQ(fn(...), 0) in tests and helper functions.

The first pass of the migration was done using Claude, followed by a
manual rework and review.

Assisted-by: Claude:claude-4.6-opus
Signed-off-by: Aleksa Sarai <aleksa@amutable.com>
---
 tools/testing/selftests/openat2/helpers.h          |  62 +---
 tools/testing/selftests/openat2/openat2_test.c     | 217 ++++++------
 .../testing/selftests/openat2/rename_attack_test.c | 161 +++++----
 tools/testing/selftests/openat2/resolve_test.c     | 368 ++++++++++++---------
 4 files changed, 396 insertions(+), 412 deletions(-)

diff --git a/tools/testing/selftests/openat2/helpers.h b/tools/testing/selftests/openat2/helpers.h
index f56c0c6e3ad1..7ca54c718c45 100644
--- a/tools/testing/selftests/openat2/helpers.h
+++ b/tools/testing/selftests/openat2/helpers.h
@@ -15,7 +15,7 @@
 #include <limits.h>
 #include <linux/types.h>
 #include <linux/unistd.h>
-#include "kselftest.h"
+#include "kselftest_harness.h"
 
 #define BUILD_BUG_ON(e) ((void)(sizeof(struct { int:(-!!(e)); })))
 
@@ -56,36 +56,6 @@ struct open_how {
 					(similar to chroot(2)). */
 #endif /* RESOLVE_IN_ROOT */
 
-#define E_func(func, ...)						      \
-	do {								      \
-		errno = 0;						      \
-		if (func(__VA_ARGS__) < 0)				      \
-			ksft_exit_fail_msg("%s:%d %s failed - errno:%d\n",    \
-					   __FILE__, __LINE__, #func, errno); \
-	} while (0)
-
-#define E_asprintf(...)		E_func(asprintf,	__VA_ARGS__)
-#define E_chmod(...)		E_func(chmod,		__VA_ARGS__)
-#define E_dup2(...)		E_func(dup2,		__VA_ARGS__)
-#define E_fchdir(...)		E_func(fchdir,		__VA_ARGS__)
-#define E_fstatat(...)		E_func(fstatat,		__VA_ARGS__)
-#define E_kill(...)		E_func(kill,		__VA_ARGS__)
-#define E_mkdirat(...)		E_func(mkdirat,		__VA_ARGS__)
-#define E_mount(...)		E_func(mount,		__VA_ARGS__)
-#define E_prctl(...)		E_func(prctl,		__VA_ARGS__)
-#define E_readlink(...)		E_func(readlink,	__VA_ARGS__)
-#define E_setresuid(...)	E_func(setresuid,	__VA_ARGS__)
-#define E_symlinkat(...)	E_func(symlinkat,	__VA_ARGS__)
-#define E_touchat(...)		E_func(touchat,		__VA_ARGS__)
-#define E_unshare(...)		E_func(unshare,		__VA_ARGS__)
-
-#define E_assert(expr, msg, ...)					\
-	do {								\
-		if (!(expr))						\
-			ksft_exit_fail_msg("ASSERT(%s:%d) failed (%s): " msg "\n", \
-					   __FILE__, __LINE__, #expr, ##__VA_ARGS__); \
-	} while (0)
-
 __maybe_unused
 static bool needs_openat2(const struct open_how *how)
 {
@@ -135,37 +105,39 @@ static int touchat(int dfd, const char *path)
 }
 
 __maybe_unused
-static char *fdreadlink(int fd)
+static char *fdreadlink(struct __test_metadata *_metadata, int fd)
 {
 	char *target, *tmp;
 
-	E_asprintf(&tmp, "/proc/self/fd/%d", fd);
+	ASSERT_GT(asprintf(&tmp, "/proc/self/fd/%d", fd), 0);
 
 	target = malloc(PATH_MAX);
-	if (!target)
-		ksft_exit_fail_msg("fdreadlink: malloc failed\n");
+	ASSERT_NE(target, NULL);
 	memset(target, 0, PATH_MAX);
 
-	E_readlink(tmp, target, PATH_MAX);
+	ASSERT_GT(readlink(tmp, target, PATH_MAX), 0);
+
 	free(tmp);
 	return target;
 }
 
 __maybe_unused
-static bool fdequal(int fd, int dfd, const char *path)
+static bool fdequal(struct __test_metadata *_metadata, int fd,
+		    int dfd, const char *path)
 {
 	char *fdpath, *dfdpath, *other;
 	bool cmp;
 
-	fdpath = fdreadlink(fd);
-	dfdpath = fdreadlink(dfd);
+	fdpath = fdreadlink(_metadata, fd);
+	dfdpath = fdreadlink(_metadata, dfd);
 
-	if (!path)
-		E_asprintf(&other, "%s", dfdpath);
-	else if (*path == '/')
-		E_asprintf(&other, "%s", path);
-	else
-		E_asprintf(&other, "%s/%s", dfdpath, path);
+	if (!path) {
+		ASSERT_GT(asprintf(&other, "%s", dfdpath), 0);
+	} else if (*path == '/') {
+		ASSERT_GT(asprintf(&other, "%s", path), 0);
+	} else {
+		ASSERT_GT(asprintf(&other, "%s/%s", dfdpath, path), 0);
+	}
 
 	cmp = !strcmp(fdpath, other);
 
diff --git a/tools/testing/selftests/openat2/openat2_test.c b/tools/testing/selftests/openat2/openat2_test.c
index c6c26652ac1b..5ea3eebb7b59 100644
--- a/tools/testing/selftests/openat2/openat2_test.c
+++ b/tools/testing/selftests/openat2/openat2_test.c
@@ -15,8 +15,8 @@
 #include <stdbool.h>
 #include <string.h>
 
-#include "kselftest.h"
 #include "helpers.h"
+#include "kselftest_harness.h"
 
 /*
  * O_LARGEFILE is set to 0 by glibc.
@@ -45,13 +45,29 @@ struct struct_test {
 	int err;
 };
 
-#define NUM_OPENAT2_STRUCT_TESTS 7
-#define NUM_OPENAT2_STRUCT_VARIATIONS 13
+struct flag_test {
+	const char *name;
+	struct open_how how;
+	int err;
+};
+
+FIXTURE(openat2) {};
 
-void test_openat2_struct(void)
+FIXTURE_SETUP(openat2)
 {
-	int misalignments[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 17, 87 };
+	if (!openat2_supported)
+		SKIP(return, "openat2(2) not supported");
+}
+
+FIXTURE_TEARDOWN(openat2) {}
 
+/*
+ * Verify that the struct size and misalignment handling for openat2(2) is
+ * correct, including that is_zeroed_user() works.
+ */
+TEST_F(openat2, struct_argument_sizes)
+{
+	int misalignments[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 17, 87 };
 	struct struct_test tests[] = {
 		/* Normal struct. */
 		{ .name = "normal struct",
@@ -83,26 +99,14 @@ void test_openat2_struct(void)
 		  .size = sizeof(struct open_how_ext), .err = -E2BIG },
 	};
 
-	BUILD_BUG_ON(ARRAY_SIZE(misalignments) != NUM_OPENAT2_STRUCT_VARIATIONS);
-	BUILD_BUG_ON(ARRAY_SIZE(tests) != NUM_OPENAT2_STRUCT_TESTS);
-
 	for (int i = 0; i < ARRAY_SIZE(tests); i++) {
 		struct struct_test *test = &tests[i];
 		struct open_how_ext how_ext = test->arg;
 
 		for (int j = 0; j < ARRAY_SIZE(misalignments); j++) {
 			int fd, misalign = misalignments[j];
-			char *fdpath = NULL;
-			bool failed;
-			void (*resultfn)(const char *msg, ...) = ksft_test_result_pass;
-
 			void *copy = NULL, *how_copy = &how_ext;
-
-			if (!openat2_supported) {
-				ksft_print_msg("openat2(2) unsupported\n");
-				resultfn = ksft_test_result_skip;
-				goto skip;
-			}
+			char *fdpath = NULL;
 
 			if (misalign) {
 				/*
@@ -119,50 +123,42 @@ void test_openat2_struct(void)
 			}
 
 			fd = raw_openat2(AT_FDCWD, ".", how_copy, test->size);
-			if (test->err >= 0)
-				failed = (fd < 0);
-			else
-				failed = (fd != test->err);
 			if (fd >= 0) {
-				fdpath = fdreadlink(fd);
+				fdpath = fdreadlink(_metadata, fd);
 				close(fd);
 			}
 
-			if (failed) {
-				resultfn = ksft_test_result_fail;
-
-				ksft_print_msg("openat2 unexpectedly returned ");
-				if (fdpath)
-					ksft_print_msg("%d['%s']\n", fd, fdpath);
-				else
-					ksft_print_msg("%d (%s)\n", fd, strerror(-fd));
+			if (test->err >= 0) {
+				EXPECT_GE(fd, 0) {
+					TH_LOG("openat2 with %s [misalign=%d] should succeed, got %d (%s)",
+					       test->name, misalign,
+					       fd, strerror(-fd));
+				}
+			} else {
+				EXPECT_EQ(test->err, fd) {
+					if (fdpath)
+						TH_LOG("openat2 with %s [misalign=%d] should fail with %d (%s), got %d['%s']",
+						       test->name, misalign,
+						       test->err,
+						       strerror(-test->err),
+						       fd, fdpath);
+					else
+						TH_LOG("openat2 with %s [misalign=%d] should fail with %d (%s), got %d (%s)",
+						       test->name, misalign,
+						       test->err,
+						       strerror(-test->err),
+						       fd, strerror(-fd));
+				}
 			}
 
-skip:
-			if (test->err >= 0)
-				resultfn("openat2 with %s argument [misalign=%d] succeeds\n",
-					 test->name, misalign);
-			else
-				resultfn("openat2 with %s argument [misalign=%d] fails with %d (%s)\n",
-					 test->name, misalign, test->err,
-					 strerror(-test->err));
-
 			free(copy);
 			free(fdpath);
-			fflush(stdout);
 		}
 	}
 }
 
-struct flag_test {
-	const char *name;
-	struct open_how how;
-	int err;
-};
-
-#define NUM_OPENAT2_FLAG_TESTS 25
-
-void test_openat2_flags(void)
+/* Verify openat2(2) flag and mode validation. */
+TEST_F(openat2, flag_validation)
 {
 	struct flag_test tests[] = {
 		/* O_TMPFILE is incompatible with O_PATH and O_CREAT. */
@@ -241,20 +237,10 @@ void test_openat2_flags(void)
 		  .how.resolve = 0, .err = -EINVAL },
 	};
 
-	BUILD_BUG_ON(ARRAY_SIZE(tests) != NUM_OPENAT2_FLAG_TESTS);
-
 	for (int i = 0; i < ARRAY_SIZE(tests); i++) {
 		int fd, fdflags = -1;
 		char *path, *fdpath = NULL;
-		bool failed = false;
 		struct flag_test *test = &tests[i];
-		void (*resultfn)(const char *msg, ...) = ksft_test_result_pass;
-
-		if (!openat2_supported) {
-			ksft_print_msg("openat2(2) unsupported\n");
-			resultfn = ksft_test_result_skip;
-			goto skip;
-		}
 
 		path = (test->how.flags & O_CREAT) ? "/tmp/ksft.openat2_tmpfile" : ".";
 		unlink(path);
@@ -265,74 +251,63 @@ void test_openat2_flags(void)
 			 * Skip the testcase if it failed because not supported
 			 * by FS. (e.g. a valid O_TMPFILE combination on NFS)
 			 */
-			ksft_test_result_skip("openat2 with %s fails with %d (%s)\n",
-					      test->name, fd, strerror(-fd));
-			goto next;
+			TH_LOG("openat2 with %s not supported by FS -- skipping",
+			       test->name);
+			continue;
 		}
 
-		if (test->err >= 0)
-			failed = (fd < 0);
-		else
-			failed = (fd != test->err);
-		if (fd >= 0) {
-			int otherflags;
-
-			fdpath = fdreadlink(fd);
-			fdflags = fcntl(fd, F_GETFL);
-			otherflags = fcntl(fd, F_GETFD);
-			close(fd);
-
-			E_assert(fdflags >= 0, "fcntl F_GETFL of new fd");
-			E_assert(otherflags >= 0, "fcntl F_GETFD of new fd");
-
-			/* O_CLOEXEC isn't shown in F_GETFL. */
-			if (otherflags & FD_CLOEXEC)
-				fdflags |= O_CLOEXEC;
-			/* O_CREAT is hidden from F_GETFL. */
-			if (test->how.flags & O_CREAT)
-				fdflags |= O_CREAT;
-			if (!(test->how.flags & O_LARGEFILE))
-				fdflags &= ~O_LARGEFILE;
-			failed |= (fdflags != test->how.flags);
-		}
+		if (test->err >= 0) {
+			EXPECT_GE(fd, 0) {
+				TH_LOG("openat2 with %s should succeed, got %d (%s)",
+				       test->name, fd, strerror(-fd));
+			}
+			if (fd >= 0) {
+				int otherflags;
 
-		if (failed) {
-			resultfn = ksft_test_result_fail;
+				fdpath = fdreadlink(_metadata, fd);
+				fdflags = fcntl(fd, F_GETFL);
+				otherflags = fcntl(fd, F_GETFD);
+				close(fd);
 
-			ksft_print_msg("openat2 unexpectedly returned ");
-			if (fdpath)
-				ksft_print_msg("%d['%s'] with %X (!= %llX)\n",
-					       fd, fdpath, fdflags,
-					       test->how.flags);
-			else
-				ksft_print_msg("%d (%s)\n", fd, strerror(-fd));
+				ASSERT_GE(fdflags, 0);
+				ASSERT_GE(otherflags, 0);
+
+				/* O_CLOEXEC isn't shown in F_GETFL. */
+				if (otherflags & FD_CLOEXEC)
+					fdflags |= O_CLOEXEC;
+				/* O_CREAT is hidden from F_GETFL. */
+				if (test->how.flags & O_CREAT)
+					fdflags |= O_CREAT;
+				if (!(test->how.flags & O_LARGEFILE))
+					fdflags &= ~O_LARGEFILE;
+
+				EXPECT_EQ(fdflags, (int)test->how.flags) {
+					TH_LOG("openat2 with %s: flags mismatch %X != %llX",
+					       test->name, fdflags,
+					       (unsigned long long)test->how.flags);
+				}
+			}
+		} else {
+			EXPECT_EQ(test->err, fd) {
+				if (fd >= 0) {
+					fdpath = fdreadlink(_metadata, fd);
+					TH_LOG("openat2 with %s should fail with %d (%s), got %d['%s']",
+					       test->name, test->err,
+					       strerror(-test->err),
+					       fd, fdpath);
+				} else {
+					TH_LOG("openat2 with %s should fail with %d (%s), got %d (%s)",
+					       test->name, test->err,
+					       strerror(-test->err),
+					       fd, strerror(-fd));
+				}
+			}
+			if (fd >= 0)
+				close(fd);
 		}
 
-skip:
-		if (test->err >= 0)
-			resultfn("openat2 with %s succeeds\n", test->name);
-		else
-			resultfn("openat2 with %s fails with %d (%s)\n",
-				 test->name, test->err, strerror(-test->err));
-next:
 		free(fdpath);
-		fflush(stdout);
 	}
 }
 
-#define NUM_TESTS (NUM_OPENAT2_STRUCT_VARIATIONS * NUM_OPENAT2_STRUCT_TESTS + \
-		   NUM_OPENAT2_FLAG_TESTS)
-
-int main(int argc, char **argv)
-{
-	ksft_print_header();
-	ksft_set_plan(NUM_TESTS);
-
-	test_openat2_struct();
-	test_openat2_flags();
-
-	if (ksft_get_fail_cnt() + ksft_get_error_cnt() > 0)
-		ksft_exit_fail();
-	else
-		ksft_exit_pass();
-}
+TEST_HARNESS_MAIN
diff --git a/tools/testing/selftests/openat2/rename_attack_test.c b/tools/testing/selftests/openat2/rename_attack_test.c
index aa5699e45729..1f33c34f56be 100644
--- a/tools/testing/selftests/openat2/rename_attack_test.c
+++ b/tools/testing/selftests/openat2/rename_attack_test.c
@@ -22,44 +22,21 @@
 #include <limits.h>
 #include <unistd.h>
 
-#include "kselftest.h"
 #include "helpers.h"
+#include "kselftest_harness.h"
 
-/* Construct a test directory with the following structure:
- *
- * root/
- * |-- a/
- * |   `-- c/
- * `-- b/
- */
-int setup_testdir(void)
-{
-	int dfd;
-	char dirname[] = "/tmp/ksft-openat2-rename-attack.XXXXXX";
-
-	/* Make the top-level directory. */
-	if (!mkdtemp(dirname))
-		ksft_exit_fail_msg("setup_testdir: failed to create tmpdir\n");
-	dfd = open(dirname, O_PATH | O_DIRECTORY);
-	if (dfd < 0)
-		ksft_exit_fail_msg("setup_testdir: failed to open tmpdir\n");
-
-	E_mkdirat(dfd, "a", 0755);
-	E_mkdirat(dfd, "b", 0755);
-	E_mkdirat(dfd, "a/c", 0755);
-
-	return dfd;
-}
+#define ROUNDS 400000
 
 /* Swap @dirfd/@a and @dirfd/@b constantly. Parent must kill this process. */
-pid_t spawn_attack(int dirfd, char *a, char *b)
+pid_t spawn_attack(struct __test_metadata *_metadata,
+		   int dirfd, char *a, char *b)
 {
 	pid_t child = fork();
 	if (child != 0)
 		return child;
 
 	/* If the parent (the test process) dies, kill ourselves too. */
-	E_prctl(PR_SET_PDEATHSIG, SIGKILL);
+	ASSERT_EQ(prctl(PR_SET_PDEATHSIG, SIGKILL), 0);
 
 	/* Swap @a and @b. */
 	for (;;)
@@ -67,52 +44,90 @@ pid_t spawn_attack(int dirfd, char *a, char *b)
 	exit(1);
 }
 
-#define NUM_RENAME_TESTS 2
-#define ROUNDS 400000
+/*
+ * Construct a test directory with the following structure:
+ *
+ * root/
+ * |-- a/
+ * |   `-- c/
+ * `-- b/
+ */
+FIXTURE(rename_attack) {
+	int dfd;
+	int afd;
+	pid_t child;
+};
 
-const char *flagname(int resolve)
+FIXTURE_SETUP(rename_attack)
 {
-	switch (resolve) {
-	case RESOLVE_IN_ROOT:
-		return "RESOLVE_IN_ROOT";
-	case RESOLVE_BENEATH:
-		return "RESOLVE_BENEATH";
-	}
-	return "(unknown)";
+	char dirname[] = "/tmp/ksft-openat2-rename-attack.XXXXXX";
+
+	self->dfd = -1;
+	self->afd = -1;
+	self->child = 0;
+
+	/* Make the top-level directory. */
+	ASSERT_NE(mkdtemp(dirname), NULL);
+	self->dfd = open(dirname, O_PATH | O_DIRECTORY);
+	ASSERT_GE(self->dfd, 0);
+
+	ASSERT_EQ(mkdirat(self->dfd, "a", 0755), 0);
+	ASSERT_EQ(mkdirat(self->dfd, "b", 0755), 0);
+	ASSERT_EQ(mkdirat(self->dfd, "a/c", 0755), 0);
+
+	self->afd = openat(self->dfd, "a", O_PATH);
+	ASSERT_GE(self->afd, 0);
+
+	self->child = spawn_attack(_metadata, self->dfd, "a/c", "b");
+	ASSERT_GT(self->child, 0);
 }
 
-void test_rename_attack(int resolve)
+FIXTURE_TEARDOWN(rename_attack)
 {
-	int dfd, afd;
-	pid_t child;
-	void (*resultfn)(const char *msg, ...) = ksft_test_result_pass;
-	int escapes = 0, other_errs = 0, exdevs = 0, eagains = 0, successes = 0;
+	if (self->child > 0)
+		kill(self->child, SIGKILL);
+	if (self->afd >= 0)
+		close(self->afd);
+	if (self->dfd >= 0)
+		close(self->dfd);
+}
+
+FIXTURE_VARIANT(rename_attack) {
+	int resolve;
+	const char *name;
+};
 
+FIXTURE_VARIANT_ADD(rename_attack, resolve_beneath) {
+	.resolve = RESOLVE_BENEATH,
+	.name = "RESOLVE_BENEATH",
+};
+
+FIXTURE_VARIANT_ADD(rename_attack, resolve_in_root) {
+	.resolve = RESOLVE_IN_ROOT,
+	.name = "RESOLVE_IN_ROOT",
+};
+
+TEST_F_TIMEOUT(rename_attack, test, 120)
+{
+	int escapes = 0, successes = 0, other_errs = 0, exdevs = 0, eagains = 0;
+	char *victim_path = "c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../..";
 	struct open_how how = {
 		.flags = O_PATH,
-		.resolve = resolve,
+		.resolve = variant->resolve,
 	};
 
 	if (!openat2_supported) {
 		how.resolve = 0;
-		ksft_print_msg("openat2(2) unsupported -- using openat(2) instead\n");
+		TH_LOG("openat2(2) unsupported -- using openat(2) instead");
 	}
 
-	dfd = setup_testdir();
-	afd = openat(dfd, "a", O_PATH);
-	if (afd < 0)
-		ksft_exit_fail_msg("test_rename_attack: failed to open 'a'\n");
-
-	child = spawn_attack(dfd, "a/c", "b");
-
 	for (int i = 0; i < ROUNDS; i++) {
 		int fd;
-		char *victim_path = "c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../..";
 
 		if (openat2_supported)
-			fd = sys_openat2(afd, victim_path, &how);
+			fd = sys_openat2(self->afd, victim_path, &how);
 		else
-			fd = sys_openat(afd, victim_path, &how);
+			fd = sys_openat(self->afd, victim_path, &how);
 
 		if (fd < 0) {
 			if (fd == -EAGAIN)
@@ -124,37 +139,21 @@ void test_rename_attack(int resolve)
 			else
 				other_errs++; /* unexpected error */
 		} else {
-			if (fdequal(fd, afd, NULL))
+			if (fdequal(_metadata, fd, self->afd, NULL))
 				successes++;
 			else
 				escapes++; /* we got an unexpected fd */
 		}
-		close(fd);
+		if (fd >= 0)
+			close(fd);
 	}
 
-	if (escapes > 0)
-		resultfn = ksft_test_result_fail;
-	ksft_print_msg("non-escapes: EAGAIN=%d EXDEV=%d E<other>=%d success=%d\n",
-		       eagains, exdevs, other_errs, successes);
-	resultfn("rename attack with %s (%d runs, got %d escapes)\n",
-		 flagname(resolve), ROUNDS, escapes);
-
-	/* Should be killed anyway, but might as well make sure. */
-	E_kill(child, SIGKILL);
+	TH_LOG("non-escapes: EAGAIN=%d EXDEV=%d E<other>=%d success=%d",
+	       eagains, exdevs, other_errs, successes);
+	ASSERT_EQ(escapes, 0) {
+		TH_LOG("rename attack with %s (%d runs, got %d escapes)",
+		       variant->name, ROUNDS, escapes);
+	}
 }
 
-#define NUM_TESTS NUM_RENAME_TESTS
-
-int main(int argc, char **argv)
-{
-	ksft_print_header();
-	ksft_set_plan(NUM_TESTS);
-
-	test_rename_attack(RESOLVE_BENEATH);
-	test_rename_attack(RESOLVE_IN_ROOT);
-
-	if (ksft_get_fail_cnt() + ksft_get_error_cnt() > 0)
-		ksft_exit_fail();
-	else
-		ksft_exit_pass();
-}
+TEST_HARNESS_MAIN
diff --git a/tools/testing/selftests/openat2/resolve_test.c b/tools/testing/selftests/openat2/resolve_test.c
index f7acb4300641..eacde59ce158 100644
--- a/tools/testing/selftests/openat2/resolve_test.c
+++ b/tools/testing/selftests/openat2/resolve_test.c
@@ -14,8 +14,81 @@
 #include <stdbool.h>
 #include <string.h>
 
-#include "kselftest.h"
 #include "helpers.h"
+#include "kselftest_harness.h"
+
+struct resolve_test {
+	const char *name;
+	const char *dir;
+	const char *path;
+	struct open_how how;
+	bool pass;
+	union {
+		int err;
+		const char *path;
+	} out;
+};
+
+/*
+ * Verify a single resolve test case. This must be called from within a TEST_F
+ * function with _metadata in scope.
+ */
+static void verify_resolve_test(struct __test_metadata *_metadata,
+				int rootfd, int hardcoded_fd,
+				const struct resolve_test *test)
+{
+	struct open_how how = test->how;
+	int dfd, fd;
+	char *fdpath = NULL;
+
+	/* Auto-set O_PATH. */
+	if (!(how.flags & O_CREAT))
+		how.flags |= O_PATH;
+
+	if (test->dir)
+		dfd = openat(rootfd, test->dir, O_PATH | O_DIRECTORY);
+	else
+		dfd = dup(rootfd);
+	ASSERT_GE(dfd, 0) TH_LOG("failed to open dir '%s': %m", test->dir ?: ".");
+	ASSERT_EQ(dup2(dfd, hardcoded_fd), hardcoded_fd);
+
+	fd = sys_openat2(dfd, test->path, &how);
+
+	if (test->pass) {
+		EXPECT_GE(fd, 0) {
+			TH_LOG("%s: expected success, got %d (%s)",
+			       test->name, fd, strerror(-fd));
+		}
+		if (fd >= 0) {
+			EXPECT_TRUE(fdequal(_metadata, fd, rootfd, test->out.path)) {
+				fdpath = fdreadlink(_metadata, fd);
+				TH_LOG("%s: wrong path '%s', expected '%s'",
+				       test->name, fdpath,
+				       test->out.path ?: ".");
+				free(fdpath);
+			}
+		}
+	} else {
+		EXPECT_EQ(test->out.err, fd) {
+			if (fd >= 0) {
+				fdpath = fdreadlink(_metadata, fd);
+				TH_LOG("%s: expected %d (%s), got %d['%s']",
+				       test->name, test->out.err,
+				       strerror(-test->out.err), fd, fdpath);
+				free(fdpath);
+			} else {
+				TH_LOG("%s: expected %d (%s), got %d (%s)",
+				       test->name, test->out.err,
+				       strerror(-test->out.err),
+				       fd, strerror(-fd));
+			}
+		}
+	}
+
+	if (fd >= 0)
+		close(fd);
+	close(dfd);
+}
 
 /*
  * Construct a test directory with the following structure:
@@ -39,101 +112,110 @@
  *     |-- absself -> /
  *     |-- self -> ../../root/
  *     |-- garbageself -> /../../root/
- *     |-- passwd -> ../cheeky/../cheeky/../etc/../etc/passwd
- *     |-- abspasswd -> /../cheeky/../cheeky/../etc/../etc/passwd
+ *     |-- passwd -> ../cheeky/../etc/../etc/passwd
+ *     |-- abspasswd -> /../cheeky/../etc/../etc/passwd
  *     |-- dotdotlink -> ../../../../../../../../../../../../../../etc/passwd
  *     `-- garbagelink -> /../../../../../../../../../../../../../../etc/passwd
  */
-int setup_testdir(void)
+FIXTURE(openat2_resolve) {
+	int rootfd;
+	int hardcoded_fd;
+	char *hardcoded_fdpath;
+	char *procselfexe;
+};
+
+FIXTURE_SETUP(openat2_resolve)
 {
-	int dfd, tmpfd;
 	char dirname[] = "/tmp/ksft-openat2-testdir.XXXXXX";
+	int dfd, tmpfd;
+
+	self->rootfd = -1;
+	self->hardcoded_fd = -1;
+	self->hardcoded_fdpath = NULL;
+	self->procselfexe = NULL;
+
+	/* NOTE: We should be checking for CAP_SYS_ADMIN here... */
+	if (geteuid() != 0)
+		SKIP(return, "all tests require euid == 0");
+	if (!openat2_supported)
+		SKIP(return, "openat2(2) not supported");
 
 	/* Unshare and make /tmp a new directory. */
-	E_unshare(CLONE_NEWNS);
-	E_mount("", "/tmp", "", MS_PRIVATE, "");
+	ASSERT_EQ(unshare(CLONE_NEWNS), 0);
+	ASSERT_EQ(mount("", "/tmp", "", MS_PRIVATE, ""), 0);
 
 	/* Make the top-level directory. */
-	if (!mkdtemp(dirname))
-		ksft_exit_fail_msg("setup_testdir: failed to create tmpdir\n");
+	ASSERT_NE(mkdtemp(dirname), NULL);
 	dfd = open(dirname, O_PATH | O_DIRECTORY);
-	if (dfd < 0)
-		ksft_exit_fail_msg("setup_testdir: failed to open tmpdir\n");
+	ASSERT_GE(dfd, 0);
 
 	/* A sub-directory which is actually used for tests. */
-	E_mkdirat(dfd, "root", 0755);
+	ASSERT_EQ(mkdirat(dfd, "root", 0755), 0);
 	tmpfd = openat(dfd, "root", O_PATH | O_DIRECTORY);
-	if (tmpfd < 0)
-		ksft_exit_fail_msg("setup_testdir: failed to open tmpdir\n");
+	ASSERT_GE(tmpfd, 0);
 	close(dfd);
 	dfd = tmpfd;
 
-	E_symlinkat("/proc/self/exe", dfd, "procexe");
-	E_symlinkat("/proc/self/root", dfd, "procroot");
-	E_mkdirat(dfd, "root", 0755);
+	ASSERT_EQ(symlinkat("/proc/self/exe", dfd, "procexe"), 0);
+	ASSERT_EQ(symlinkat("/proc/self/root", dfd, "procroot"), 0);
+	ASSERT_EQ(mkdirat(dfd, "root", 0755), 0);
 
 	/* There is no mountat(2), so use chdir. */
-	E_mkdirat(dfd, "mnt", 0755);
-	E_fchdir(dfd);
-	E_mount("tmpfs", "./mnt", "tmpfs", MS_NOSUID | MS_NODEV, "");
-	E_symlinkat("../mnt/", dfd, "mnt/self");
-	E_symlinkat("/mnt/", dfd, "mnt/absself");
-
-	E_mkdirat(dfd, "etc", 0755);
-	E_touchat(dfd, "etc/passwd");
-
-	E_symlinkat("/newfile3", dfd, "creatlink");
-	E_symlinkat("etc/", dfd, "reletc");
-	E_symlinkat("etc/passwd", dfd, "relsym");
-	E_symlinkat("/etc/", dfd, "absetc");
-	E_symlinkat("/etc/passwd", dfd, "abssym");
-	E_symlinkat("/cheeky", dfd, "abscheeky");
-
-	E_mkdirat(dfd, "cheeky", 0755);
-
-	E_symlinkat("/", dfd, "cheeky/absself");
-	E_symlinkat("../../root/", dfd, "cheeky/self");
-	E_symlinkat("/../../root/", dfd, "cheeky/garbageself");
-
-	E_symlinkat("../cheeky/../etc/../etc/passwd", dfd, "cheeky/passwd");
-	E_symlinkat("/../cheeky/../etc/../etc/passwd", dfd, "cheeky/abspasswd");
-
-	E_symlinkat("../../../../../../../../../../../../../../etc/passwd",
-		    dfd, "cheeky/dotdotlink");
-	E_symlinkat("/../../../../../../../../../../../../../../etc/passwd",
-		    dfd, "cheeky/garbagelink");
-
-	return dfd;
+	ASSERT_EQ(mkdirat(dfd, "mnt", 0755), 0);
+	ASSERT_EQ(fchdir(dfd), 0);
+	ASSERT_EQ(mount("tmpfs", "./mnt", "tmpfs", MS_NOSUID | MS_NODEV, ""), 0);
+	ASSERT_EQ(symlinkat("../mnt/", dfd, "mnt/self"), 0);
+	ASSERT_EQ(symlinkat("/mnt/", dfd, "mnt/absself"), 0);
+
+	ASSERT_EQ(mkdirat(dfd, "etc", 0755), 0);
+	ASSERT_GE(touchat(dfd, "etc/passwd"), 0);
+
+	ASSERT_EQ(symlinkat("/newfile3", dfd, "creatlink"), 0);
+	ASSERT_EQ(symlinkat("etc/", dfd, "reletc"), 0);
+	ASSERT_EQ(symlinkat("etc/passwd", dfd, "relsym"), 0);
+	ASSERT_EQ(symlinkat("/etc/", dfd, "absetc"), 0);
+	ASSERT_EQ(symlinkat("/etc/passwd", dfd, "abssym"), 0);
+	ASSERT_EQ(symlinkat("/cheeky", dfd, "abscheeky"), 0);
+
+	ASSERT_EQ(mkdirat(dfd, "cheeky", 0755), 0);
+
+	ASSERT_EQ(symlinkat("/", dfd, "cheeky/absself"), 0);
+	ASSERT_EQ(symlinkat("../../root/", dfd, "cheeky/self"), 0);
+	ASSERT_EQ(symlinkat("/../../root/", dfd, "cheeky/garbageself"), 0);
+
+	ASSERT_EQ(symlinkat("../cheeky/../etc/../etc/passwd",
+			    dfd, "cheeky/passwd"), 0);
+	ASSERT_EQ(symlinkat("/../cheeky/../etc/../etc/passwd",
+			    dfd, "cheeky/abspasswd"), 0);
+
+	ASSERT_EQ(symlinkat("../../../../../../../../../../../../../../etc/passwd",
+			    dfd, "cheeky/dotdotlink"), 0);
+	ASSERT_EQ(symlinkat("/../../../../../../../../../../../../../../etc/passwd",
+			    dfd, "cheeky/garbagelink"), 0);
+
+	self->rootfd = dfd;
+
+	self->hardcoded_fd = open("/dev/null", O_RDONLY);
+	ASSERT_GE(self->hardcoded_fd, 0);
+	ASSERT_GE(asprintf(&self->hardcoded_fdpath, "self/fd/%d",
+			   self->hardcoded_fd), 0);
+	ASSERT_GE(asprintf(&self->procselfexe, "/proc/%d/exe", getpid()), 0);
 }
 
-struct basic_test {
-	const char *name;
-	const char *dir;
-	const char *path;
-	struct open_how how;
-	bool pass;
-	union {
-		int err;
-		const char *path;
-	} out;
-};
-
-#define NUM_OPENAT2_OPATH_TESTS 88
-
-void test_openat2_opath_tests(void)
+FIXTURE_TEARDOWN(openat2_resolve)
 {
-	int rootfd, hardcoded_fd;
-	char *procselfexe, *hardcoded_fdpath;
-
-	E_asprintf(&procselfexe, "/proc/%d/exe", getpid());
-	rootfd = setup_testdir();
-
-	hardcoded_fd = open("/dev/null", O_RDONLY);
-	E_assert(hardcoded_fd >= 0, "open fd to hardcode");
-	E_asprintf(&hardcoded_fdpath, "self/fd/%d", hardcoded_fd);
+	free(self->procselfexe);
+	free(self->hardcoded_fdpath);
+	if (self->hardcoded_fd >= 0)
+		close(self->hardcoded_fd);
+	if (self->rootfd >= 0)
+		close(self->rootfd);
+}
 
-	struct basic_test tests[] = {
-		/** RESOLVE_BENEATH **/
+/* Attempts to cross the dirfd should be blocked with -EXDEV. */
+TEST_F(openat2_resolve, resolve_beneath)
+{
+	struct resolve_test tests[] = {
 		/* Attempts to cross dirfd should be blocked. */
 		{ .name = "[beneath] jump to /",
 		  .path = "/",			.how.resolve = RESOLVE_BENEATH,
@@ -206,9 +288,17 @@ void test_openat2_opath_tests(void)
 		{ .name = "[beneath] tricky absolute + garbage link outside $root",
 		  .path = "abscheeky/garbagelink", .how.resolve = RESOLVE_BENEATH,
 		  .out.err = -EXDEV,		.pass = false },
+	};
+
+	for (int i = 0; i < ARRAY_SIZE(tests); i++)
+		verify_resolve_test(_metadata, self->rootfd,
+				    self->hardcoded_fd, &tests[i]);
+}
 
-		/** RESOLVE_IN_ROOT **/
-		/* All attempts to cross the dirfd will be scoped-to-root. */
+/* All attempts to cross the dirfd will be scoped-to-root. */
+TEST_F(openat2_resolve, resolve_in_root)
+{
+	struct resolve_test tests[] = {
 		{ .name = "[in_root] jump to /",
 		  .path = "/",			.how.resolve = RESOLVE_IN_ROOT,
 		  .out.path = NULL,		.pass = true },
@@ -297,8 +387,17 @@ void test_openat2_opath_tests(void)
 						.how.mode = 0700,
 						.how.resolve = RESOLVE_IN_ROOT,
 		  .out.path = "newfile3",	.pass = true },
+	};
 
-		/** RESOLVE_NO_XDEV **/
+	for (int i = 0; i < ARRAY_SIZE(tests); i++)
+		verify_resolve_test(_metadata, self->rootfd,
+				    self->hardcoded_fd, &tests[i]);
+}
+
+/* Crossing mount boundaries should be blocked. */
+TEST_F(openat2_resolve, resolve_no_xdev)
+{
+	struct resolve_test tests[] = {
 		/* Crossing *down* into a mountpoint is disallowed. */
 		{ .name = "[no_xdev] cross into $mnt",
 		  .path = "mnt",		.how.resolve = RESOLVE_NO_XDEV,
@@ -347,10 +446,19 @@ void test_openat2_opath_tests(void)
 		  .out.err = -EXDEV,			.pass = false },
 		/* Except magic-link jumps inside the same vfsmount. */
 		{ .name = "[no_xdev] jump through magic-link to same procfs",
-		  .dir = "/proc", .path = hardcoded_fdpath, .how.resolve = RESOLVE_NO_XDEV,
-		  .out.path = "/proc",			    .pass = true, },
+		  .dir = "/proc", .path = self->hardcoded_fdpath, .how.resolve = RESOLVE_NO_XDEV,
+		  .out.path = "/proc",				  .pass = true, },
+	};
+
+	for (int i = 0; i < ARRAY_SIZE(tests); i++)
+		verify_resolve_test(_metadata, self->rootfd,
+				    self->hardcoded_fd, &tests[i]);
+}
 
-		/** RESOLVE_NO_MAGICLINKS **/
+/* Procfs-style magic-link resolution should be blocked. */
+TEST_F(openat2_resolve, resolve_no_magiclinks)
+{
+	struct resolve_test tests[] = {
 		/* Regular symlinks should work. */
 		{ .name = "[no_magiclinks] ordinary relative symlink",
 		  .path = "relsym",		.how.resolve = RESOLVE_NO_MAGICLINKS,
@@ -365,7 +473,7 @@ void test_openat2_opath_tests(void)
 		{ .name = "[no_magiclinks] normal path to magic-link with O_NOFOLLOW",
 		  .path = "/proc/self/exe",	.how.flags = O_NOFOLLOW,
 						.how.resolve = RESOLVE_NO_MAGICLINKS,
-		  .out.path = procselfexe,	.pass = true },
+		  .out.path = self->procselfexe, .pass = true },
 		{ .name = "[no_magiclinks] symlink to magic-link path component",
 		  .path = "procroot/etc",	.how.resolve = RESOLVE_NO_MAGICLINKS,
 		  .out.err = -ELOOP,		.pass = false },
@@ -376,8 +484,17 @@ void test_openat2_opath_tests(void)
 		  .path = "/proc/self/root/etc", .how.flags = O_NOFOLLOW,
 						 .how.resolve = RESOLVE_NO_MAGICLINKS,
 		  .out.err = -ELOOP,		.pass = false },
+	};
+
+	for (int i = 0; i < ARRAY_SIZE(tests); i++)
+		verify_resolve_test(_metadata, self->rootfd,
+				    self->hardcoded_fd, &tests[i]);
+}
 
-		/** RESOLVE_NO_SYMLINKS **/
+/* All symlink resolution should be blocked. */
+TEST_F(openat2_resolve, resolve_no_symlinks)
+{
+	struct resolve_test tests[] = {
 		/* Normal paths should work. */
 		{ .name = "[no_symlinks] ordinary path to '.'",
 		  .path = ".",			.how.resolve = RESOLVE_NO_SYMLINKS,
@@ -436,88 +553,9 @@ void test_openat2_opath_tests(void)
 		  .out.err = -ELOOP,		.pass = false },
 	};
 
-	BUILD_BUG_ON(ARRAY_SIZE(tests) != NUM_OPENAT2_OPATH_TESTS);
-
-	for (int i = 0; i < ARRAY_SIZE(tests); i++) {
-		int dfd, fd;
-		char *fdpath = NULL;
-		bool failed;
-		void (*resultfn)(const char *msg, ...) = ksft_test_result_pass;
-		struct basic_test *test = &tests[i];
-
-		if (!openat2_supported) {
-			ksft_print_msg("openat2(2) unsupported\n");
-			resultfn = ksft_test_result_skip;
-			goto skip;
-		}
-
-		/* Auto-set O_PATH. */
-		if (!(test->how.flags & O_CREAT))
-			test->how.flags |= O_PATH;
-
-		if (test->dir)
-			dfd = openat(rootfd, test->dir, O_PATH | O_DIRECTORY);
-		else
-			dfd = dup(rootfd);
-		E_assert(dfd, "failed to openat root '%s': %m", test->dir);
-
-		E_dup2(dfd, hardcoded_fd);
-
-		fd = sys_openat2(dfd, test->path, &test->how);
-		if (test->pass)
-			failed = (fd < 0 || !fdequal(fd, rootfd, test->out.path));
-		else
-			failed = (fd != test->out.err);
-		if (fd >= 0) {
-			fdpath = fdreadlink(fd);
-			close(fd);
-		}
-		close(dfd);
-
-		if (failed) {
-			resultfn = ksft_test_result_fail;
-
-			ksft_print_msg("openat2 unexpectedly returned ");
-			if (fdpath)
-				ksft_print_msg("%d['%s']\n", fd, fdpath);
-			else
-				ksft_print_msg("%d (%s)\n", fd, strerror(-fd));
-		}
-
-skip:
-		if (test->pass)
-			resultfn("%s gives path '%s'\n", test->name,
-				 test->out.path ?: ".");
-		else
-			resultfn("%s fails with %d (%s)\n", test->name,
-				 test->out.err, strerror(-test->out.err));
-
-		fflush(stdout);
-		free(fdpath);
-	}
-
-	free(procselfexe);
-	close(rootfd);
-
-	free(hardcoded_fdpath);
-	close(hardcoded_fd);
+	for (int i = 0; i < ARRAY_SIZE(tests); i++)
+		verify_resolve_test(_metadata, self->rootfd,
+				    self->hardcoded_fd, &tests[i]);
 }
 
-#define NUM_TESTS NUM_OPENAT2_OPATH_TESTS
-
-int main(int argc, char **argv)
-{
-	ksft_print_header();
-	ksft_set_plan(NUM_TESTS);
-
-	/* NOTE: We should be checking for CAP_SYS_ADMIN here... */
-	if (geteuid() != 0)
-		ksft_exit_skip("all tests require euid == 0\n");
-
-	test_openat2_opath_tests();
-
-	if (ksft_get_fail_cnt() + ksft_get_error_cnt() > 0)
-		ksft_exit_fail();
-	else
-		ksft_exit_pass();
-}
+TEST_HARNESS_MAIN

-- 
2.53.0

Re: [PATCH 0/3] selftests: openat2: migrate to kselftests harness

[Christian Brauner]

On Wed, Apr 01, 2026 at 12:43:30AM +1100, Aleksa Sarai wrote:
> These tests were written in the early days of selftests' TAP support,
> the more modern kselftest harness is much easier to follow and maintain.
> The actual contents of the tests are unchanged by this change.
> 
> Signed-off-by: Aleksa Sarai <aleksa@amutable.com>
> ---

Looks all good to me. Do you want to maybe migrate the tests to the
filesystems/ subfolder as well?

Re: [PATCH 0/3] selftests: openat2: migrate to kselftests harness

[Aleksa Sarai]

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On 2026-03-31, Christian Brauner <brauner@kernel.org> wrote:
> On Wed, Apr 01, 2026 at 12:43:30AM +1100, Aleksa Sarai wrote:
> > These tests were written in the early days of selftests' TAP support,
> > the more modern kselftest harness is much easier to follow and maintain.
> > The actual contents of the tests are unchanged by this change.
> > 
> > Signed-off-by: Aleksa Sarai <aleksa@amutable.com>
> > ---
> 
> Looks all good to me. Do you want to maybe migrate the tests to the
> filesystems/ subfolder as well?

Good point, I'll move it over in v2.

-- 
Aleksa Sarai
https://www.cyphar.com/

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Re: [PATCH 0/3] selftests: openat2: migrate to kselftests harness

[Christian Brauner]

On Wed, Apr 01, 2026 at 02:10:16AM +1100, Aleksa Sarai wrote:
> On 2026-03-31, Christian Brauner <brauner@kernel.org> wrote:
> > On Wed, Apr 01, 2026 at 12:43:30AM +1100, Aleksa Sarai wrote:
> > > These tests were written in the early days of selftests' TAP support,
> > > the more modern kselftest harness is much easier to follow and maintain.
> > > The actual contents of the tests are unchanged by this change.
> > > 
> > > Signed-off-by: Aleksa Sarai <aleksa@amutable.com>
> > > ---
> > 
> > Looks all good to me. Do you want to maybe migrate the tests to the
> > filesystems/ subfolder as well?
> 
> Good point, I'll move it over in v2.

Thank you!