Resguardo inicial

linux-7.2.3/tools/testing/selftests/filesystems/overlayfs/.gitignore

@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0-only
+dev_in_maps
+set_layers_via_fds

linux-7.2.3/tools/testing/selftests/filesystems/overlayfs/Makefile

@@ -0,0 +1,14 @@
+# SPDX-License-Identifier: GPL-2.0
+
+CFLAGS += -Wall
+CFLAGS += $(KHDR_INCLUDES)
+LDLIBS += -lcap
+
+LOCAL_HDRS += ../wrappers.h log.h
+
+TEST_GEN_PROGS := dev_in_maps
+TEST_GEN_PROGS += set_layers_via_fds
+
+include ../../lib.mk
+
+$(OUTPUT)/set_layers_via_fds: ../utils.c

linux-7.2.3/tools/testing/selftests/filesystems/overlayfs/dev_in_maps.c

@@ -0,0 +1,160 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#define __SANE_USERSPACE_TYPES__ // Use ll64
+
+#include <inttypes.h>
+#include <unistd.h>
+#include <stdio.h>
+
+#include <linux/unistd.h>
+#include <linux/types.h>
+#include <linux/mount.h>
+#include <sys/syscall.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+#include <sched.h>
+#include <fcntl.h>
+
+#include "kselftest.h"
+#include "log.h"
+#include "../wrappers.h"
+
+static long get_file_dev_and_inode(void *addr, struct statx *stx)
+{
+	char buf[4096];
+	FILE *mapf;
+
+	mapf = fopen("/proc/self/maps", "r");
+	if (mapf == NULL)
+		return pr_perror("fopen(/proc/self/maps)");
+
+	while (fgets(buf, sizeof(buf), mapf)) {
+		unsigned long start, end;
+		uint32_t maj, min;
+		__u64 ino;
+
+		if (sscanf(buf, "%lx-%lx %*s %*s %x:%x %llu",
+				&start, &end, &maj, &min, &ino) != 5)
+			return pr_perror("unable to parse: %s", buf);
+		if (start == (unsigned long)addr) {
+			stx->stx_dev_major = maj;
+			stx->stx_dev_minor = min;
+			stx->stx_ino = ino;
+			return 0;
+		}
+	}
+
+	return pr_err("unable to find the mapping");
+}
+
+static int ovl_mount(void)
+{
+	int tmpfs, fsfd, ovl;
+
+	fsfd = sys_fsopen("tmpfs", 0);
+	if (fsfd == -1)
+		return pr_perror("fsopen(tmpfs)");
+
+	if (sys_fsconfig(fsfd, FSCONFIG_CMD_CREATE, NULL, NULL, 0) == -1)
+		return pr_perror("FSCONFIG_CMD_CREATE");
+
+	tmpfs = sys_fsmount(fsfd, 0, 0);
+	if (tmpfs == -1)
+		return pr_perror("fsmount");
+
+	close(fsfd);
+
+	/* overlayfs can't be constructed on top of a detached mount. */
+	if (sys_move_mount(tmpfs, "", AT_FDCWD, "/tmp", MOVE_MOUNT_F_EMPTY_PATH))
+		return pr_perror("move_mount");
+	close(tmpfs);
+
+	if (mkdir("/tmp/w", 0755) == -1 ||
+	    mkdir("/tmp/u", 0755) == -1 ||
+	    mkdir("/tmp/l", 0755) == -1)
+		return pr_perror("mkdir");
+
+	fsfd = sys_fsopen("overlay", 0);
+	if (fsfd == -1)
+		return pr_perror("fsopen(overlay)");
+	if (sys_fsconfig(fsfd, FSCONFIG_SET_STRING, "source", "test", 0) == -1 ||
+	    sys_fsconfig(fsfd, FSCONFIG_SET_STRING, "lowerdir", "/tmp/l", 0) == -1 ||
+	    sys_fsconfig(fsfd, FSCONFIG_SET_STRING, "upperdir", "/tmp/u", 0) == -1 ||
+	    sys_fsconfig(fsfd, FSCONFIG_SET_STRING, "workdir", "/tmp/w", 0) == -1)
+		return pr_perror("fsconfig");
+	if (sys_fsconfig(fsfd, FSCONFIG_CMD_CREATE, NULL, NULL, 0) == -1)
+		return pr_perror("fsconfig");
+	ovl = sys_fsmount(fsfd, 0, 0);
+	if (ovl == -1)
+		return pr_perror("fsmount");
+
+	return ovl;
+}
+
+/*
+ * Check that the file device and inode shown in /proc/pid/maps match values
+ * returned by stat(2).
+ */
+static int test(void)
+{
+	struct statx stx, mstx;
+	int ovl, fd;
+	void *addr;
+
+	ovl = ovl_mount();
+	if (ovl == -1)
+		return -1;
+
+	fd = openat(ovl, "test", O_RDWR | O_CREAT, 0644);
+	if (fd == -1)
+		return pr_perror("openat");
+
+	addr = mmap(NULL, 4096, PROT_READ | PROT_WRITE, MAP_FILE | MAP_SHARED, fd, 0);
+	if (addr == MAP_FAILED)
+		return pr_perror("mmap");
+
+	if (get_file_dev_and_inode(addr, &mstx))
+		return -1;
+	if (statx(fd, "", AT_EMPTY_PATH | AT_STATX_SYNC_AS_STAT, STATX_INO, &stx))
+		return pr_perror("statx");
+
+	if (stx.stx_dev_major != mstx.stx_dev_major ||
+	    stx.stx_dev_minor != mstx.stx_dev_minor ||
+	    stx.stx_ino != mstx.stx_ino)
+		return pr_fail("unmatched dev:ino %x:%x:%llx (expected %x:%x:%llx)\n",
+			mstx.stx_dev_major, mstx.stx_dev_minor, mstx.stx_ino,
+			stx.stx_dev_major, stx.stx_dev_minor, stx.stx_ino);
+
+	ksft_test_result_pass("devices are matched\n");
+	return 0;
+}
+
+int main(int argc, char **argv)
+{
+	int fsfd;
+
+	fsfd = sys_fsopen("overlay", 0);
+	if (fsfd == -1) {
+		ksft_test_result_skip("unable to create overlay mount\n");
+		return 1;
+	}
+	close(fsfd);
+
+	/* Create a new mount namespace to not care about cleaning test mounts. */
+	if (unshare(CLONE_NEWNS) == -1) {
+		ksft_test_result_skip("unable to create a new mount namespace\n");
+		return 1;
+	}
+	if (sys_mount(NULL, "/", NULL, MS_SLAVE | MS_REC, NULL) == -1) {
+		pr_perror("mount");
+		return 1;
+	}
+
+	ksft_set_plan(1);
+
+	if (test())
+		return 1;
+
+	ksft_exit_pass();
+	return 0;
+}

linux-7.2.3/tools/testing/selftests/filesystems/overlayfs/log.h

@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __SELFTEST_TIMENS_LOG_H__
+#define __SELFTEST_TIMENS_LOG_H__
+
+#define pr_msg(fmt, lvl, ...)						\
+	ksft_print_msg("[%s] (%s:%d)\t" fmt "\n",			\
+			lvl, __FILE__, __LINE__, ##__VA_ARGS__)
+
+#define pr_p(func, fmt, ...)	func(fmt ": %m", ##__VA_ARGS__)
+
+#define pr_err(fmt, ...)						\
+	({								\
+		ksft_test_result_error(fmt "\n", ##__VA_ARGS__);		\
+		-1;							\
+	})
+
+#define pr_fail(fmt, ...)					\
+	({							\
+		ksft_test_result_fail(fmt, ##__VA_ARGS__);	\
+		-1;						\
+	})
+
+#define pr_perror(fmt, ...)	pr_p(pr_err, fmt, ##__VA_ARGS__)
+
+#endif

linux-7.2.3/tools/testing/selftests/filesystems/overlayfs/set_layers_via_fds.c

@@ -0,0 +1,720 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#define __SANE_USERSPACE_TYPES__ // Use ll64
+
+#include <fcntl.h>
+#include <sched.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/sysmacros.h>
+#include <sys/mount.h>
+#include <unistd.h>
+
+#include "kselftest_harness.h"
+#include "../../pidfd/pidfd.h"
+#include "log.h"
+#include "../utils.h"
+#include "../wrappers.h"
+
+FIXTURE(set_layers_via_fds) {
+	int pidfd;
+};
+
+FIXTURE_SETUP(set_layers_via_fds)
+{
+	self->pidfd = -EBADF;
+	EXPECT_EQ(mkdir("/set_layers_via_fds", 0755), 0);
+	EXPECT_EQ(mkdir("/set_layers_via_fds_tmpfs", 0755), 0);
+}
+
+FIXTURE_TEARDOWN(set_layers_via_fds)
+{
+	if (self->pidfd >= 0) {
+		EXPECT_EQ(sys_pidfd_send_signal(self->pidfd, SIGKILL, NULL, 0), 0);
+		EXPECT_EQ(close(self->pidfd), 0);
+	}
+	umount2("/set_layers_via_fds", 0);
+	EXPECT_EQ(rmdir("/set_layers_via_fds"), 0);
+
+	umount2("/set_layers_via_fds_tmpfs", 0);
+	EXPECT_EQ(rmdir("/set_layers_via_fds_tmpfs"), 0);
+}
+
+TEST_F(set_layers_via_fds, set_layers_via_fds)
+{
+	int fd_context, fd_tmpfs, fd_overlay;
+	int layer_fds[] = { [0 ... 8] = -EBADF };
+	bool layers_found[] = { [0 ... 8] =  false };
+	size_t len = 0;
+	char *line = NULL;
+	FILE *f_mountinfo;
+
+	ASSERT_EQ(unshare(CLONE_NEWNS), 0);
+	ASSERT_EQ(sys_mount(NULL, "/", NULL, MS_SLAVE | MS_REC, NULL), 0);
+
+	fd_context = sys_fsopen("tmpfs", 0);
+	ASSERT_GE(fd_context, 0);
+
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_CMD_CREATE, NULL, NULL, 0), 0);
+	fd_tmpfs = sys_fsmount(fd_context, 0, 0);
+	ASSERT_GE(fd_tmpfs, 0);
+	ASSERT_EQ(close(fd_context), 0);
+
+	ASSERT_EQ(mkdirat(fd_tmpfs, "w", 0755), 0);
+	ASSERT_EQ(mkdirat(fd_tmpfs, "u", 0755), 0);
+	ASSERT_EQ(mkdirat(fd_tmpfs, "l1", 0755), 0);
+	ASSERT_EQ(mkdirat(fd_tmpfs, "l2", 0755), 0);
+	ASSERT_EQ(mkdirat(fd_tmpfs, "l3", 0755), 0);
+	ASSERT_EQ(mkdirat(fd_tmpfs, "l4", 0755), 0);
+	ASSERT_EQ(mkdirat(fd_tmpfs, "d1", 0755), 0);
+	ASSERT_EQ(mkdirat(fd_tmpfs, "d2", 0755), 0);
+	ASSERT_EQ(mkdirat(fd_tmpfs, "d3", 0755), 0);
+
+	layer_fds[0] = openat(fd_tmpfs, "w", O_DIRECTORY);
+	ASSERT_GE(layer_fds[0], 0);
+
+	layer_fds[1] = openat(fd_tmpfs, "u", O_DIRECTORY);
+	ASSERT_GE(layer_fds[1], 0);
+
+	layer_fds[2] = openat(fd_tmpfs, "l1", O_DIRECTORY);
+	ASSERT_GE(layer_fds[2], 0);
+
+	layer_fds[3] = openat(fd_tmpfs, "l2", O_DIRECTORY);
+	ASSERT_GE(layer_fds[3], 0);
+
+	layer_fds[4] = openat(fd_tmpfs, "l3", O_DIRECTORY);
+	ASSERT_GE(layer_fds[4], 0);
+
+	layer_fds[5] = openat(fd_tmpfs, "l4", O_DIRECTORY);
+	ASSERT_GE(layer_fds[5], 0);
+
+	layer_fds[6] = openat(fd_tmpfs, "d1", O_DIRECTORY);
+	ASSERT_GE(layer_fds[6], 0);
+
+	layer_fds[7] = openat(fd_tmpfs, "d2", O_DIRECTORY);
+	ASSERT_GE(layer_fds[7], 0);
+
+	layer_fds[8] = openat(fd_tmpfs, "d3", O_DIRECTORY);
+	ASSERT_GE(layer_fds[8], 0);
+
+	ASSERT_EQ(sys_move_mount(fd_tmpfs, "", -EBADF, "/tmp", MOVE_MOUNT_F_EMPTY_PATH), 0);
+	ASSERT_EQ(close(fd_tmpfs), 0);
+
+	fd_context = sys_fsopen("overlay", 0);
+	ASSERT_GE(fd_context, 0);
+
+	ASSERT_NE(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir", NULL, layer_fds[2]), 0);
+
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "workdir",   NULL, layer_fds[0]), 0);
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "upperdir",  NULL, layer_fds[1]), 0);
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir+", NULL, layer_fds[2]), 0);
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir+", NULL, layer_fds[3]), 0);
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir+", NULL, layer_fds[4]), 0);
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir+", NULL, layer_fds[5]), 0);
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "datadir+",  NULL, layer_fds[6]), 0);
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "datadir+",  NULL, layer_fds[7]), 0);
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "datadir+",  NULL, layer_fds[8]), 0);
+
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_STRING, "metacopy", "on", 0), 0);
+
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_CMD_CREATE, NULL, NULL, 0), 0);
+
+	fd_overlay = sys_fsmount(fd_context, 0, 0);
+	ASSERT_GE(fd_overlay, 0);
+
+	ASSERT_EQ(sys_move_mount(fd_overlay, "", -EBADF, "/set_layers_via_fds", MOVE_MOUNT_F_EMPTY_PATH), 0);
+
+	f_mountinfo = fopen("/proc/self/mountinfo", "r");
+	ASSERT_NE(f_mountinfo, NULL);
+
+	while (getline(&line, &len, f_mountinfo) != -1) {
+		char *haystack = line;
+
+		if (strstr(haystack, "workdir=/tmp/w"))
+			layers_found[0] = true;
+		if (strstr(haystack, "upperdir=/tmp/u"))
+			layers_found[1] = true;
+		if (strstr(haystack, "lowerdir+=/tmp/l1"))
+			layers_found[2] = true;
+		if (strstr(haystack, "lowerdir+=/tmp/l2"))
+			layers_found[3] = true;
+		if (strstr(haystack, "lowerdir+=/tmp/l3"))
+			layers_found[4] = true;
+		if (strstr(haystack, "lowerdir+=/tmp/l4"))
+			layers_found[5] = true;
+		if (strstr(haystack, "datadir+=/tmp/d1"))
+			layers_found[6] = true;
+		if (strstr(haystack, "datadir+=/tmp/d2"))
+			layers_found[7] = true;
+		if (strstr(haystack, "datadir+=/tmp/d3"))
+			layers_found[8] = true;
+	}
+	free(line);
+
+	for (int i = 0; i < ARRAY_SIZE(layer_fds); i++) {
+		ASSERT_EQ(layers_found[i], true);
+		ASSERT_EQ(close(layer_fds[i]), 0);
+	}
+
+	ASSERT_EQ(close(fd_context), 0);
+	ASSERT_EQ(close(fd_overlay), 0);
+	ASSERT_EQ(fclose(f_mountinfo), 0);
+}
+
+TEST_F(set_layers_via_fds, set_500_layers_via_fds)
+{
+	int fd_context, fd_tmpfs, fd_overlay, fd_work, fd_upper, fd_lower;
+	int layer_fds[500] = { [0 ... 499] = -EBADF };
+
+	ASSERT_EQ(unshare(CLONE_NEWNS), 0);
+	ASSERT_EQ(sys_mount(NULL, "/", NULL, MS_SLAVE | MS_REC, NULL), 0);
+
+	fd_context = sys_fsopen("tmpfs", 0);
+	ASSERT_GE(fd_context, 0);
+
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_CMD_CREATE, NULL, NULL, 0), 0);
+	fd_tmpfs = sys_fsmount(fd_context, 0, 0);
+	ASSERT_GE(fd_tmpfs, 0);
+	ASSERT_EQ(close(fd_context), 0);
+
+	for (int i = 0; i < ARRAY_SIZE(layer_fds); i++) {
+		char path[100];
+
+		sprintf(path, "l%d", i);
+		ASSERT_EQ(mkdirat(fd_tmpfs, path, 0755), 0);
+		layer_fds[i] = openat(fd_tmpfs, path, O_DIRECTORY);
+		ASSERT_GE(layer_fds[i], 0);
+	}
+
+	ASSERT_EQ(mkdirat(fd_tmpfs, "w", 0755), 0);
+	fd_work = openat(fd_tmpfs, "w", O_DIRECTORY);
+	ASSERT_GE(fd_work, 0);
+
+	ASSERT_EQ(mkdirat(fd_tmpfs, "u", 0755), 0);
+	fd_upper = openat(fd_tmpfs, "u", O_DIRECTORY);
+	ASSERT_GE(fd_upper, 0);
+
+	ASSERT_EQ(mkdirat(fd_tmpfs, "l501", 0755), 0);
+	fd_lower = openat(fd_tmpfs, "l501", O_DIRECTORY);
+	ASSERT_GE(fd_lower, 0);
+
+	ASSERT_EQ(sys_move_mount(fd_tmpfs, "", -EBADF, "/tmp", MOVE_MOUNT_F_EMPTY_PATH), 0);
+	ASSERT_EQ(close(fd_tmpfs), 0);
+
+	fd_context = sys_fsopen("overlay", 0);
+	ASSERT_GE(fd_context, 0);
+
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "workdir",   NULL, fd_work), 0);
+	ASSERT_EQ(close(fd_work), 0);
+
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "upperdir",  NULL, fd_upper), 0);
+	ASSERT_EQ(close(fd_upper), 0);
+
+	for (int i = 0; i < ARRAY_SIZE(layer_fds); i++) {
+		ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir+", NULL, layer_fds[i]), 0);
+		ASSERT_EQ(close(layer_fds[i]), 0);
+	}
+
+	ASSERT_NE(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir+", NULL, fd_lower), 0);
+	ASSERT_EQ(close(fd_lower), 0);
+
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_CMD_CREATE, NULL, NULL, 0), 0);
+
+	fd_overlay = sys_fsmount(fd_context, 0, 0);
+	ASSERT_GE(fd_overlay, 0);
+	ASSERT_EQ(close(fd_context), 0);
+	ASSERT_EQ(close(fd_overlay), 0);
+}
+
+TEST_F(set_layers_via_fds, set_override_creds)
+{
+	int fd_context, fd_tmpfs, fd_overlay;
+	int layer_fds[] = { [0 ... 3] = -EBADF };
+	pid_t pid;
+	int pidfd;
+
+	ASSERT_EQ(unshare(CLONE_NEWNS), 0);
+	ASSERT_EQ(sys_mount(NULL, "/", NULL, MS_SLAVE | MS_REC, NULL), 0);
+
+	fd_context = sys_fsopen("tmpfs", 0);
+	ASSERT_GE(fd_context, 0);
+
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_CMD_CREATE, NULL, NULL, 0), 0);
+	fd_tmpfs = sys_fsmount(fd_context, 0, 0);
+	ASSERT_GE(fd_tmpfs, 0);
+	ASSERT_EQ(close(fd_context), 0);
+
+	ASSERT_EQ(mkdirat(fd_tmpfs, "w", 0755), 0);
+	ASSERT_EQ(mkdirat(fd_tmpfs, "u", 0755), 0);
+	ASSERT_EQ(mkdirat(fd_tmpfs, "l1", 0755), 0);
+	ASSERT_EQ(mkdirat(fd_tmpfs, "l2", 0755), 0);
+
+	layer_fds[0] = openat(fd_tmpfs, "w", O_DIRECTORY);
+	ASSERT_GE(layer_fds[0], 0);
+
+	layer_fds[1] = openat(fd_tmpfs, "u", O_DIRECTORY);
+	ASSERT_GE(layer_fds[1], 0);
+
+	layer_fds[2] = openat(fd_tmpfs, "l1", O_DIRECTORY);
+	ASSERT_GE(layer_fds[2], 0);
+
+	layer_fds[3] = openat(fd_tmpfs, "l2", O_DIRECTORY);
+	ASSERT_GE(layer_fds[3], 0);
+
+	ASSERT_EQ(sys_move_mount(fd_tmpfs, "", -EBADF, "/tmp", MOVE_MOUNT_F_EMPTY_PATH), 0);
+	ASSERT_EQ(close(fd_tmpfs), 0);
+
+	fd_context = sys_fsopen("overlay", 0);
+	ASSERT_GE(fd_context, 0);
+
+	ASSERT_NE(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir", NULL, layer_fds[2]), 0);
+
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "workdir",   NULL, layer_fds[0]), 0);
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "upperdir",  NULL, layer_fds[1]), 0);
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir+", NULL, layer_fds[2]), 0);
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir+", NULL, layer_fds[3]), 0);
+
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_STRING, "metacopy", "on", 0), 0);
+
+	pid = create_child(&pidfd, 0);
+	ASSERT_GE(pid, 0);
+	if (pid == 0) {
+		if (sys_fsconfig(fd_context, FSCONFIG_SET_FLAG, "override_creds", NULL, 0)) {
+			TH_LOG("sys_fsconfig should have succeeded");
+			_exit(EXIT_FAILURE);
+		}
+
+		_exit(EXIT_SUCCESS);
+	}
+	ASSERT_GE(sys_waitid(P_PID, pid, NULL, WEXITED), 0);
+	ASSERT_GE(close(pidfd), 0);
+
+	pid = create_child(&pidfd, 0);
+	ASSERT_GE(pid, 0);
+	if (pid == 0) {
+		if (sys_fsconfig(fd_context, FSCONFIG_SET_FLAG, "nooverride_creds", NULL, 0)) {
+			TH_LOG("sys_fsconfig should have succeeded");
+			_exit(EXIT_FAILURE);
+		}
+
+		_exit(EXIT_SUCCESS);
+	}
+	ASSERT_GE(sys_waitid(P_PID, pid, NULL, WEXITED), 0);
+	ASSERT_GE(close(pidfd), 0);
+
+	pid = create_child(&pidfd, 0);
+	ASSERT_GE(pid, 0);
+	if (pid == 0) {
+		if (sys_fsconfig(fd_context, FSCONFIG_SET_FLAG, "override_creds", NULL, 0)) {
+			TH_LOG("sys_fsconfig should have succeeded");
+			_exit(EXIT_FAILURE);
+		}
+
+		_exit(EXIT_SUCCESS);
+	}
+	ASSERT_GE(sys_waitid(P_PID, pid, NULL, WEXITED), 0);
+	ASSERT_GE(close(pidfd), 0);
+
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_CMD_CREATE, NULL, NULL, 0), 0);
+
+	fd_overlay = sys_fsmount(fd_context, 0, 0);
+	ASSERT_GE(fd_overlay, 0);
+
+	ASSERT_EQ(sys_move_mount(fd_overlay, "", -EBADF, "/set_layers_via_fds", MOVE_MOUNT_F_EMPTY_PATH), 0);
+
+	ASSERT_EQ(close(fd_context), 0);
+	ASSERT_EQ(close(fd_overlay), 0);
+}
+
+TEST_F(set_layers_via_fds, set_override_creds_invalid)
+{
+	int fd_context, fd_tmpfs, fd_overlay, ret;
+	int layer_fds[] = { [0 ... 3] = -EBADF };
+	pid_t pid;
+	int fd_userns1, fd_userns2;
+	int ipc_sockets[2];
+	char c;
+	const unsigned int predictable_fd_context_nr = 123;
+
+	fd_userns1 = get_userns_fd(0, 0, 10000);
+	ASSERT_GE(fd_userns1, 0);
+
+	fd_userns2 = get_userns_fd(0, 1234, 10000);
+	ASSERT_GE(fd_userns2, 0);
+
+	ret = socketpair(AF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, ipc_sockets);
+	ASSERT_GE(ret, 0);
+
+	pid = create_child(&self->pidfd, 0);
+	ASSERT_GE(pid, 0);
+	if (pid == 0) {
+		if (close(ipc_sockets[0])) {
+			TH_LOG("close should have succeeded");
+			_exit(EXIT_FAILURE);
+		}
+
+		if (!switch_userns(fd_userns2, 0, 0, false)) {
+			TH_LOG("switch_userns should have succeeded");
+			_exit(EXIT_FAILURE);
+		}
+
+		if (read_nointr(ipc_sockets[1], &c, 1) != 1) {
+			TH_LOG("read_nointr should have succeeded");
+			_exit(EXIT_FAILURE);
+		}
+
+		if (close(ipc_sockets[1])) {
+			TH_LOG("close should have succeeded");
+			_exit(EXIT_FAILURE);
+		}
+
+		if (!sys_fsconfig(predictable_fd_context_nr, FSCONFIG_SET_FLAG, "override_creds", NULL, 0)) {
+			TH_LOG("sys_fsconfig should have failed");
+			_exit(EXIT_FAILURE);
+		}
+
+		_exit(EXIT_SUCCESS);
+	}
+
+	ASSERT_EQ(close(ipc_sockets[1]), 0);
+	ASSERT_EQ(switch_userns(fd_userns1, 0, 0, false), true);
+	ASSERT_EQ(unshare(CLONE_NEWNS), 0);
+	ASSERT_EQ(sys_mount(NULL, "/", NULL, MS_SLAVE | MS_REC, NULL), 0);
+
+	fd_context = sys_fsopen("tmpfs", 0);
+	ASSERT_GE(fd_context, 0);
+
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_CMD_CREATE, NULL, NULL, 0), 0);
+	fd_tmpfs = sys_fsmount(fd_context, 0, 0);
+	ASSERT_GE(fd_tmpfs, 0);
+	ASSERT_EQ(close(fd_context), 0);
+
+	ASSERT_EQ(mkdirat(fd_tmpfs, "w", 0755), 0);
+	ASSERT_EQ(mkdirat(fd_tmpfs, "u", 0755), 0);
+	ASSERT_EQ(mkdirat(fd_tmpfs, "l1", 0755), 0);
+	ASSERT_EQ(mkdirat(fd_tmpfs, "l2", 0755), 0);
+
+	layer_fds[0] = openat(fd_tmpfs, "w", O_DIRECTORY);
+	ASSERT_GE(layer_fds[0], 0);
+
+	layer_fds[1] = openat(fd_tmpfs, "u", O_DIRECTORY);
+	ASSERT_GE(layer_fds[1], 0);
+
+	layer_fds[2] = openat(fd_tmpfs, "l1", O_DIRECTORY);
+	ASSERT_GE(layer_fds[2], 0);
+
+	layer_fds[3] = openat(fd_tmpfs, "l2", O_DIRECTORY);
+	ASSERT_GE(layer_fds[3], 0);
+
+	ASSERT_EQ(sys_move_mount(fd_tmpfs, "", -EBADF, "/tmp", MOVE_MOUNT_F_EMPTY_PATH), 0);
+	ASSERT_EQ(close(fd_tmpfs), 0);
+
+	fd_context = sys_fsopen("overlay", 0);
+	ASSERT_GE(fd_context, 0);
+	ASSERT_EQ(dup3(fd_context, predictable_fd_context_nr, 0), predictable_fd_context_nr);
+	ASSERT_EQ(close(fd_context), 0);
+	fd_context = predictable_fd_context_nr;
+	ASSERT_EQ(write_nointr(ipc_sockets[0], "1", 1), 1);
+	ASSERT_EQ(close(ipc_sockets[0]), 0);
+
+	ASSERT_EQ(wait_for_pid(pid), 0);
+	ASSERT_EQ(close(self->pidfd), 0);
+	self->pidfd = -EBADF;
+
+	ASSERT_NE(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir", NULL, layer_fds[2]), 0);
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "workdir",   NULL, layer_fds[0]), 0);
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "upperdir",  NULL, layer_fds[1]), 0);
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir+", NULL, layer_fds[2]), 0);
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir+", NULL, layer_fds[3]), 0);
+
+	for (int i = 0; i < ARRAY_SIZE(layer_fds); i++)
+		ASSERT_EQ(close(layer_fds[i]), 0);
+
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FLAG, "userxattr", NULL, 0), 0);
+
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_CMD_CREATE, NULL, NULL, 0), 0);
+
+	fd_overlay = sys_fsmount(fd_context, 0, 0);
+	ASSERT_GE(fd_overlay, 0);
+
+	ASSERT_EQ(sys_move_mount(fd_overlay, "", -EBADF, "/set_layers_via_fds", MOVE_MOUNT_F_EMPTY_PATH), 0);
+
+	ASSERT_EQ(close(fd_context), 0);
+	ASSERT_EQ(close(fd_overlay), 0);
+	ASSERT_EQ(close(fd_userns1), 0);
+	ASSERT_EQ(close(fd_userns2), 0);
+}
+
+TEST_F(set_layers_via_fds, set_override_creds_nomknod)
+{
+	int fd_context, fd_tmpfs, fd_overlay;
+	int layer_fds[] = { [0 ... 3] = -EBADF };
+	pid_t pid;
+	int pidfd;
+
+	ASSERT_EQ(unshare(CLONE_NEWNS), 0);
+	ASSERT_EQ(sys_mount(NULL, "/", NULL, MS_SLAVE | MS_REC, NULL), 0);
+
+	fd_context = sys_fsopen("tmpfs", 0);
+	ASSERT_GE(fd_context, 0);
+
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_CMD_CREATE, NULL, NULL, 0), 0);
+	fd_tmpfs = sys_fsmount(fd_context, 0, 0);
+	ASSERT_GE(fd_tmpfs, 0);
+	ASSERT_EQ(close(fd_context), 0);
+
+	ASSERT_EQ(mkdirat(fd_tmpfs, "w", 0755), 0);
+	ASSERT_EQ(mkdirat(fd_tmpfs, "u", 0755), 0);
+	ASSERT_EQ(mkdirat(fd_tmpfs, "l1", 0755), 0);
+	ASSERT_EQ(mkdirat(fd_tmpfs, "l2", 0755), 0);
+
+	layer_fds[0] = openat(fd_tmpfs, "w", O_DIRECTORY);
+	ASSERT_GE(layer_fds[0], 0);
+
+	layer_fds[1] = openat(fd_tmpfs, "u", O_DIRECTORY);
+	ASSERT_GE(layer_fds[1], 0);
+
+	layer_fds[2] = openat(fd_tmpfs, "l1", O_DIRECTORY);
+	ASSERT_GE(layer_fds[2], 0);
+
+	layer_fds[3] = openat(fd_tmpfs, "l2", O_DIRECTORY);
+	ASSERT_GE(layer_fds[3], 0);
+
+	ASSERT_EQ(sys_move_mount(fd_tmpfs, "", -EBADF, "/tmp", MOVE_MOUNT_F_EMPTY_PATH), 0);
+	ASSERT_EQ(close(fd_tmpfs), 0);
+
+	fd_context = sys_fsopen("overlay", 0);
+	ASSERT_GE(fd_context, 0);
+
+	ASSERT_NE(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir", NULL, layer_fds[2]), 0);
+
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "workdir",   NULL, layer_fds[0]), 0);
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "upperdir",  NULL, layer_fds[1]), 0);
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir+", NULL, layer_fds[2]), 0);
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir+", NULL, layer_fds[3]), 0);
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FLAG, "userxattr", NULL, 0), 0);
+
+	pid = create_child(&pidfd, 0);
+	ASSERT_GE(pid, 0);
+	if (pid == 0) {
+		if (!cap_down(CAP_MKNOD))
+			_exit(EXIT_FAILURE);
+
+		if (!cap_down(CAP_SYS_ADMIN))
+			_exit(EXIT_FAILURE);
+
+		if (sys_fsconfig(fd_context, FSCONFIG_SET_FLAG, "override_creds", NULL, 0))
+			_exit(EXIT_FAILURE);
+
+		_exit(EXIT_SUCCESS);
+	}
+	ASSERT_EQ(sys_waitid(P_PID, pid, NULL, WEXITED), 0);
+	ASSERT_GE(close(pidfd), 0);
+
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_CMD_CREATE, NULL, NULL, 0), 0);
+
+	fd_overlay = sys_fsmount(fd_context, 0, 0);
+	ASSERT_GE(fd_overlay, 0);
+
+	ASSERT_EQ(sys_move_mount(fd_overlay, "", -EBADF, "/set_layers_via_fds", MOVE_MOUNT_F_EMPTY_PATH), 0);
+	ASSERT_EQ(mknodat(fd_overlay, "dev-zero", S_IFCHR | 0644, makedev(1, 5)), -1);
+	ASSERT_EQ(errno, EPERM);
+
+	ASSERT_EQ(close(fd_context), 0);
+	ASSERT_EQ(close(fd_overlay), 0);
+}
+
+TEST_F(set_layers_via_fds, set_500_layers_via_opath_fds)
+{
+	int fd_context, fd_tmpfs, fd_overlay, fd_work, fd_upper, fd_lower;
+	int layer_fds[500] = { [0 ... 499] = -EBADF };
+
+	ASSERT_EQ(unshare(CLONE_NEWNS), 0);
+	ASSERT_EQ(sys_mount(NULL, "/", NULL, MS_SLAVE | MS_REC, NULL), 0);
+
+	fd_context = sys_fsopen("tmpfs", 0);
+	ASSERT_GE(fd_context, 0);
+
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_CMD_CREATE, NULL, NULL, 0), 0);
+	fd_tmpfs = sys_fsmount(fd_context, 0, 0);
+	ASSERT_GE(fd_tmpfs, 0);
+	ASSERT_EQ(close(fd_context), 0);
+
+	for (int i = 0; i < ARRAY_SIZE(layer_fds); i++) {
+		char path[100];
+
+		sprintf(path, "l%d", i);
+		ASSERT_EQ(mkdirat(fd_tmpfs, path, 0755), 0);
+		layer_fds[i] = openat(fd_tmpfs, path, O_DIRECTORY | O_PATH);
+		ASSERT_GE(layer_fds[i], 0);
+	}
+
+	ASSERT_EQ(mkdirat(fd_tmpfs, "w", 0755), 0);
+	fd_work = openat(fd_tmpfs, "w", O_DIRECTORY | O_PATH);
+	ASSERT_GE(fd_work, 0);
+
+	ASSERT_EQ(mkdirat(fd_tmpfs, "u", 0755), 0);
+	fd_upper = openat(fd_tmpfs, "u", O_DIRECTORY | O_PATH);
+	ASSERT_GE(fd_upper, 0);
+
+	ASSERT_EQ(mkdirat(fd_tmpfs, "l501", 0755), 0);
+	fd_lower = openat(fd_tmpfs, "l501", O_DIRECTORY | O_PATH);
+	ASSERT_GE(fd_lower, 0);
+
+	ASSERT_EQ(sys_move_mount(fd_tmpfs, "", -EBADF, "/tmp", MOVE_MOUNT_F_EMPTY_PATH), 0);
+	ASSERT_EQ(close(fd_tmpfs), 0);
+
+	fd_context = sys_fsopen("overlay", 0);
+	ASSERT_GE(fd_context, 0);
+
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "workdir",   NULL, fd_work), 0);
+	ASSERT_EQ(close(fd_work), 0);
+
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "upperdir",  NULL, fd_upper), 0);
+	ASSERT_EQ(close(fd_upper), 0);
+
+	for (int i = 0; i < ARRAY_SIZE(layer_fds); i++) {
+		ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir+", NULL, layer_fds[i]), 0);
+		ASSERT_EQ(close(layer_fds[i]), 0);
+	}
+
+	ASSERT_NE(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir+", NULL, fd_lower), 0);
+	ASSERT_EQ(close(fd_lower), 0);
+
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_CMD_CREATE, NULL, NULL, 0), 0);
+
+	fd_overlay = sys_fsmount(fd_context, 0, 0);
+	ASSERT_GE(fd_overlay, 0);
+	ASSERT_EQ(close(fd_context), 0);
+	ASSERT_EQ(close(fd_overlay), 0);
+}
+
+TEST_F(set_layers_via_fds, set_layers_via_detached_mount_fds)
+{
+	int fd_context, fd_tmpfs, fd_overlay, fd_tmp;
+	int layer_fds[] = { [0 ... 8] = -EBADF };
+	bool layers_found[] = { [0 ... 8] =  false };
+	size_t len = 0;
+	char *line = NULL;
+	FILE *f_mountinfo;
+
+	ASSERT_EQ(unshare(CLONE_NEWNS), 0);
+	ASSERT_EQ(sys_mount(NULL, "/", NULL, MS_SLAVE | MS_REC, NULL), 0);
+
+	fd_context = sys_fsopen("tmpfs", 0);
+	ASSERT_GE(fd_context, 0);
+
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_CMD_CREATE, NULL, NULL, 0), 0);
+	fd_tmpfs = sys_fsmount(fd_context, 0, 0);
+	ASSERT_GE(fd_tmpfs, 0);
+	ASSERT_EQ(close(fd_context), 0);
+
+	ASSERT_EQ(mkdirat(fd_tmpfs, "u", 0755), 0);
+	ASSERT_EQ(mkdirat(fd_tmpfs, "u/upper", 0755), 0);
+	ASSERT_EQ(mkdirat(fd_tmpfs, "u/work", 0755), 0);
+	ASSERT_EQ(mkdirat(fd_tmpfs, "l1", 0755), 0);
+	ASSERT_EQ(mkdirat(fd_tmpfs, "l2", 0755), 0);
+	ASSERT_EQ(mkdirat(fd_tmpfs, "l3", 0755), 0);
+	ASSERT_EQ(mkdirat(fd_tmpfs, "l4", 0755), 0);
+	ASSERT_EQ(mkdirat(fd_tmpfs, "d1", 0755), 0);
+	ASSERT_EQ(mkdirat(fd_tmpfs, "d2", 0755), 0);
+	ASSERT_EQ(mkdirat(fd_tmpfs, "d3", 0755), 0);
+
+	ASSERT_EQ(sys_move_mount(fd_tmpfs, "", -EBADF, "/set_layers_via_fds_tmpfs", MOVE_MOUNT_F_EMPTY_PATH), 0);
+
+	fd_tmp = open_tree(fd_tmpfs, "u", OPEN_TREE_CLONE | OPEN_TREE_CLOEXEC);
+	ASSERT_GE(fd_tmp, 0);
+
+	layer_fds[0] = openat(fd_tmp, "upper", O_CLOEXEC | O_DIRECTORY | O_PATH);
+	ASSERT_GE(layer_fds[0], 0);
+
+	layer_fds[1] = openat(fd_tmp, "work", O_CLOEXEC | O_DIRECTORY | O_PATH);
+	ASSERT_GE(layer_fds[1], 0);
+
+	layer_fds[2] = open_tree(fd_tmpfs, "l1", OPEN_TREE_CLONE | OPEN_TREE_CLOEXEC);
+	ASSERT_GE(layer_fds[2], 0);
+
+	layer_fds[3] = open_tree(fd_tmpfs, "l2", OPEN_TREE_CLONE | OPEN_TREE_CLOEXEC);
+	ASSERT_GE(layer_fds[3], 0);
+
+	layer_fds[4] = open_tree(fd_tmpfs, "l3", OPEN_TREE_CLONE | OPEN_TREE_CLOEXEC);
+	ASSERT_GE(layer_fds[4], 0);
+
+	layer_fds[5] = open_tree(fd_tmpfs, "l4", OPEN_TREE_CLONE | OPEN_TREE_CLOEXEC);
+	ASSERT_GE(layer_fds[5], 0);
+
+	layer_fds[6] = open_tree(fd_tmpfs, "d1", OPEN_TREE_CLONE | OPEN_TREE_CLOEXEC);
+	ASSERT_GE(layer_fds[6], 0);
+
+	layer_fds[7] = open_tree(fd_tmpfs, "d2", OPEN_TREE_CLONE | OPEN_TREE_CLOEXEC);
+	ASSERT_GE(layer_fds[7], 0);
+
+	layer_fds[8] = open_tree(fd_tmpfs, "d3", OPEN_TREE_CLONE | OPEN_TREE_CLOEXEC);
+	ASSERT_GE(layer_fds[8], 0);
+
+	ASSERT_EQ(close(fd_tmpfs), 0);
+
+	fd_context = sys_fsopen("overlay", 0);
+	ASSERT_GE(fd_context, 0);
+
+	ASSERT_NE(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir", NULL, layer_fds[2]), 0);
+
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "upperdir",  NULL, layer_fds[0]), 0);
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "workdir",   NULL, layer_fds[1]), 0);
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir+", NULL, layer_fds[2]), 0);
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir+", NULL, layer_fds[3]), 0);
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir+", NULL, layer_fds[4]), 0);
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir+", NULL, layer_fds[5]), 0);
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "datadir+",  NULL, layer_fds[6]), 0);
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "datadir+",  NULL, layer_fds[7]), 0);
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "datadir+",  NULL, layer_fds[8]), 0);
+
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_STRING, "metacopy", "on", 0), 0);
+
+	ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_CMD_CREATE, NULL, NULL, 0), 0);
+
+	fd_overlay = sys_fsmount(fd_context, 0, 0);
+	ASSERT_GE(fd_overlay, 0);
+
+	ASSERT_EQ(sys_move_mount(fd_overlay, "", -EBADF, "/set_layers_via_fds", MOVE_MOUNT_F_EMPTY_PATH), 0);
+
+	f_mountinfo = fopen("/proc/self/mountinfo", "r");
+	ASSERT_NE(f_mountinfo, NULL);
+
+	while (getline(&line, &len, f_mountinfo) != -1) {
+		char *haystack = line;
+
+		if (strstr(haystack, "workdir=/tmp/w"))
+			layers_found[0] = true;
+		if (strstr(haystack, "upperdir=/tmp/u"))
+			layers_found[1] = true;
+		if (strstr(haystack, "lowerdir+=/tmp/l1"))
+			layers_found[2] = true;
+		if (strstr(haystack, "lowerdir+=/tmp/l2"))
+			layers_found[3] = true;
+		if (strstr(haystack, "lowerdir+=/tmp/l3"))
+			layers_found[4] = true;
+		if (strstr(haystack, "lowerdir+=/tmp/l4"))
+			layers_found[5] = true;
+		if (strstr(haystack, "datadir+=/tmp/d1"))
+			layers_found[6] = true;
+		if (strstr(haystack, "datadir+=/tmp/d2"))
+			layers_found[7] = true;
+		if (strstr(haystack, "datadir+=/tmp/d3"))
+			layers_found[8] = true;
+	}
+	free(line);
+
+	for (int i = 0; i < ARRAY_SIZE(layer_fds); i++) {
+		ASSERT_EQ(layers_found[i], true);
+		ASSERT_EQ(close(layer_fds[i]), 0);
+	}
+
+	ASSERT_EQ(close(fd_context), 0);
+	ASSERT_EQ(close(fd_overlay), 0);
+	ASSERT_EQ(fclose(f_mountinfo), 0);
+}
+
+TEST_HARNESS_MAIN