selftests: add memfd_create() + sealing tests (4f5ce5e8) · Commits · 戴 / test

tools/testing/selftests/Makefile

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	@@ -2,6 +2,7 @@ TARGETS = breakpoints
	TARGETS += cpu-hotplug		TARGETS += cpu-hotplug
	TARGETS += efivarfs		TARGETS += efivarfs
	TARGETS += kcmp		TARGETS += kcmp
			TARGETS += memfd
	TARGETS += memory-hotplug		TARGETS += memory-hotplug
	TARGETS += mqueue		TARGETS += mqueue
	TARGETS += net		TARGETS += net

tools/testing/selftests/memfd/.gitignore

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			memfd_test
			memfd-test-file

tools/testing/selftests/memfd/Makefile

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			uname_M := $(shell uname -m 2>/dev/null \|\| echo not)
			ARCH ?= $(shell echo $(uname_M) \| sed -e s/i.86/i386/)
			ifeq ($(ARCH),i386)
			ARCH := X86
			endif
			ifeq ($(ARCH),x86_64)
			ARCH := X86
			endif

			CFLAGS += -I../../../../arch/x86/include/generated/uapi/
			CFLAGS += -I../../../../arch/x86/include/uapi/
			CFLAGS += -I../../../../include/uapi/
			CFLAGS += -I../../../../include/

			all:
			ifeq ($(ARCH),X86)
			gcc $(CFLAGS) memfd_test.c -o memfd_test
			else
			echo "Not an x86 target, can't build memfd selftest"
			endif

			run_tests: all
			ifeq ($(ARCH),X86)
			gcc $(CFLAGS) memfd_test.c -o memfd_test
			endif
			@./memfd_test \|\| echo "memfd_test: [FAIL]"

			clean:
			$(RM) memfd_test

tools/testing/selftests/memfd/memfd_test.c

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+913 −0

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			#define _GNU_SOURCE
			#define __EXPORTED_HEADERS__

			#include <errno.h>
			#include <inttypes.h>
			#include <limits.h>
			#include <linux/falloc.h>
			#include <linux/fcntl.h>
			#include <linux/memfd.h>
			#include <sched.h>
			#include <stdio.h>
			#include <stdlib.h>
			#include <signal.h>
			#include <string.h>
			#include <sys/mman.h>
			#include <sys/stat.h>
			#include <sys/syscall.h>
			#include <unistd.h>

			#define MFD_DEF_SIZE 8192
			#define STACK_SIZE 65535

			static int sys_memfd_create(const char *name,
			unsigned int flags)
			{
			return syscall(__NR_memfd_create, name, flags);
			}

			static int mfd_assert_new(const char *name, loff_t sz, unsigned int flags)
			{
			int r, fd;

			fd = sys_memfd_create(name, flags);
			if (fd < 0) {
			printf("memfd_create(\"%s\", %u) failed: %m\n",
			name, flags);
			abort();
			}

			r = ftruncate(fd, sz);
			if (r < 0) {
			printf("ftruncate(%llu) failed: %m\n", (unsigned long long)sz);
			abort();
			}

			return fd;
			}

			static void mfd_fail_new(const char *name, unsigned int flags)
			{
			int r;

			r = sys_memfd_create(name, flags);
			if (r >= 0) {
			printf("memfd_create(\"%s\", %u) succeeded, but failure expected\n",
			name, flags);
			close(r);
			abort();
			}
			}

			static __u64 mfd_assert_get_seals(int fd)
			{
			long r;

			r = fcntl(fd, F_GET_SEALS);
			if (r < 0) {
			printf("GET_SEALS(%d) failed: %m\n", fd);
			abort();
			}

			return r;
			}

			static void mfd_assert_has_seals(int fd, __u64 seals)
			{
			__u64 s;

			s = mfd_assert_get_seals(fd);
			if (s != seals) {
			printf("%llu != %llu = GET_SEALS(%d)\n",
			(unsigned long long)seals, (unsigned long long)s, fd);
			abort();
			}
			}

			static void mfd_assert_add_seals(int fd, __u64 seals)
			{
			long r;
			__u64 s;

			s = mfd_assert_get_seals(fd);
			r = fcntl(fd, F_ADD_SEALS, seals);
			if (r < 0) {
			printf("ADD_SEALS(%d, %llu -> %llu) failed: %m\n",
			fd, (unsigned long long)s, (unsigned long long)seals);
			abort();
			}
			}

			static void mfd_fail_add_seals(int fd, __u64 seals)
			{
			long r;
			__u64 s;

			r = fcntl(fd, F_GET_SEALS);
			if (r < 0)
			s = 0;
			else
			s = r;

			r = fcntl(fd, F_ADD_SEALS, seals);
			if (r >= 0) {
			printf("ADD_SEALS(%d, %llu -> %llu) didn't fail as expected\n",
			fd, (unsigned long long)s, (unsigned long long)seals);
			abort();
			}
			}

			static void mfd_assert_size(int fd, size_t size)
			{
			struct stat st;
			int r;

			r = fstat(fd, &st);
			if (r < 0) {
			printf("fstat(%d) failed: %m\n", fd);
			abort();
			} else if (st.st_size != size) {
			printf("wrong file size %lld, but expected %lld\n",
			(long long)st.st_size, (long long)size);
			abort();
			}
			}

			static int mfd_assert_dup(int fd)
			{
			int r;

			r = dup(fd);
			if (r < 0) {
			printf("dup(%d) failed: %m\n", fd);
			abort();
			}

			return r;
			}

			static void *mfd_assert_mmap_shared(int fd)
			{
			void *p;

			p = mmap(NULL,
			MFD_DEF_SIZE,
			PROT_READ \| PROT_WRITE,
			MAP_SHARED,
			fd,
			0);
			if (p == MAP_FAILED) {
			printf("mmap() failed: %m\n");
			abort();
			}

			return p;
			}

			static void *mfd_assert_mmap_private(int fd)
			{
			void *p;

			p = mmap(NULL,
			MFD_DEF_SIZE,
			PROT_READ,
			MAP_PRIVATE,
			fd,
			0);
			if (p == MAP_FAILED) {
			printf("mmap() failed: %m\n");
			abort();
			}

			return p;
			}

			static int mfd_assert_open(int fd, int flags, mode_t mode)
			{
			char buf[512];
			int r;

			sprintf(buf, "/proc/self/fd/%d", fd);
			r = open(buf, flags, mode);
			if (r < 0) {
			printf("open(%s) failed: %m\n", buf);
			abort();
			}

			return r;
			}

			static void mfd_fail_open(int fd, int flags, mode_t mode)
			{
			char buf[512];
			int r;

			sprintf(buf, "/proc/self/fd/%d", fd);
			r = open(buf, flags, mode);
			if (r >= 0) {
			printf("open(%s) didn't fail as expected\n");
			abort();
			}
			}

			static void mfd_assert_read(int fd)
			{
			char buf[16];
			void *p;
			ssize_t l;

			l = read(fd, buf, sizeof(buf));
			if (l != sizeof(buf)) {
			printf("read() failed: %m\n");
			abort();
			}

			/* verify PROT_READ is allowed */
			p = mmap(NULL,
			MFD_DEF_SIZE,
			PROT_READ,
			MAP_PRIVATE,
			fd,
			0);
			if (p == MAP_FAILED) {
			printf("mmap() failed: %m\n");
			abort();
			}
			munmap(p, MFD_DEF_SIZE);

			/* verify MAP_PRIVATE is always allowed (even writable) */
			p = mmap(NULL,
			MFD_DEF_SIZE,
			PROT_READ \| PROT_WRITE,
			MAP_PRIVATE,
			fd,
			0);
			if (p == MAP_FAILED) {
			printf("mmap() failed: %m\n");
			abort();
			}
			munmap(p, MFD_DEF_SIZE);
			}

			static void mfd_assert_write(int fd)
			{
			ssize_t l;
			void *p;
			int r;

			/* verify write() succeeds */
			l = write(fd, "\0\0\0\0", 4);
			if (l != 4) {
			printf("write() failed: %m\n");
			abort();
			}

			/* verify PROT_READ \| PROT_WRITE is allowed */
			p = mmap(NULL,
			MFD_DEF_SIZE,
			PROT_READ \| PROT_WRITE,
			MAP_SHARED,
			fd,
			0);
			if (p == MAP_FAILED) {
			printf("mmap() failed: %m\n");
			abort();
			}
			(char )p = 0;
			munmap(p, MFD_DEF_SIZE);

			/* verify PROT_WRITE is allowed */
			p = mmap(NULL,
			MFD_DEF_SIZE,
			PROT_WRITE,
			MAP_SHARED,
			fd,
			0);
			if (p == MAP_FAILED) {
			printf("mmap() failed: %m\n");
			abort();
			}
			(char )p = 0;
			munmap(p, MFD_DEF_SIZE);

			/* verify PROT_READ with MAP_SHARED is allowed and a following
			* mprotect(PROT_WRITE) allows writing */
			p = mmap(NULL,
			MFD_DEF_SIZE,
			PROT_READ,
			MAP_SHARED,
			fd,
			0);
			if (p == MAP_FAILED) {
			printf("mmap() failed: %m\n");
			abort();
			}

			r = mprotect(p, MFD_DEF_SIZE, PROT_READ \| PROT_WRITE);
			if (r < 0) {
			printf("mprotect() failed: %m\n");
			abort();
			}

			(char )p = 0;
			munmap(p, MFD_DEF_SIZE);

			/* verify PUNCH_HOLE works */
			r = fallocate(fd,
			FALLOC_FL_PUNCH_HOLE \| FALLOC_FL_KEEP_SIZE,
			0,
			MFD_DEF_SIZE);
			if (r < 0) {
			printf("fallocate(PUNCH_HOLE) failed: %m\n");
			abort();
			}
			}

			static void mfd_fail_write(int fd)
			{
			ssize_t l;
			void *p;
			int r;

			/* verify write() fails */
			l = write(fd, "data", 4);
			if (l != -EPERM) {
			printf("expected EPERM on write(), but got %d: %m\n", (int)l);
			abort();
			}

			/* verify PROT_READ \| PROT_WRITE is not allowed */
			p = mmap(NULL,
			MFD_DEF_SIZE,
			PROT_READ \| PROT_WRITE,
			MAP_SHARED,
			fd,
			0);
			if (p != MAP_FAILED) {
			printf("mmap() didn't fail as expected\n");
			abort();
			}

			/* verify PROT_WRITE is not allowed */
			p = mmap(NULL,
			MFD_DEF_SIZE,
			PROT_WRITE,
			MAP_SHARED,
			fd,
			0);
			if (p != MAP_FAILED) {
			printf("mmap() didn't fail as expected\n");
			abort();
			}

			/* Verify PROT_READ with MAP_SHARED with a following mprotect is not
			* allowed. Note that for r/w the kernel already prevents the mmap. */
			p = mmap(NULL,
			MFD_DEF_SIZE,
			PROT_READ,
			MAP_SHARED,
			fd,
			0);
			if (p != MAP_FAILED) {
			r = mprotect(p, MFD_DEF_SIZE, PROT_READ \| PROT_WRITE);
			if (r >= 0) {
			printf("mmap()+mprotect() didn't fail as expected\n");
			abort();
			}
			}

			/* verify PUNCH_HOLE fails */
			r = fallocate(fd,
			FALLOC_FL_PUNCH_HOLE \| FALLOC_FL_KEEP_SIZE,
			0,
			MFD_DEF_SIZE);
			if (r >= 0) {
			printf("fallocate(PUNCH_HOLE) didn't fail as expected\n");
			abort();
			}
			}

			static void mfd_assert_shrink(int fd)
			{
			int r, fd2;

			r = ftruncate(fd, MFD_DEF_SIZE / 2);
			if (r < 0) {
			printf("ftruncate(SHRINK) failed: %m\n");
			abort();
			}

			mfd_assert_size(fd, MFD_DEF_SIZE / 2);

			fd2 = mfd_assert_open(fd,
			O_RDWR \| O_CREAT \| O_TRUNC,
			S_IRUSR \| S_IWUSR);
			close(fd2);

			mfd_assert_size(fd, 0);
			}

			static void mfd_fail_shrink(int fd)
			{
			int r;

			r = ftruncate(fd, MFD_DEF_SIZE / 2);
			if (r >= 0) {
			printf("ftruncate(SHRINK) didn't fail as expected\n");
			abort();
			}

			mfd_fail_open(fd,
			O_RDWR \| O_CREAT \| O_TRUNC,
			S_IRUSR \| S_IWUSR);
			}

			static void mfd_assert_grow(int fd)
			{
			int r;

			r = ftruncate(fd, MFD_DEF_SIZE * 2);
			if (r < 0) {
			printf("ftruncate(GROW) failed: %m\n");
			abort();
			}

			mfd_assert_size(fd, MFD_DEF_SIZE * 2);

			r = fallocate(fd,
			0,
			0,
			MFD_DEF_SIZE * 4);
			if (r < 0) {
			printf("fallocate(ALLOC) failed: %m\n");
			abort();
			}

			mfd_assert_size(fd, MFD_DEF_SIZE * 4);
			}

			static void mfd_fail_grow(int fd)
			{
			int r;

			r = ftruncate(fd, MFD_DEF_SIZE * 2);
			if (r >= 0) {
			printf("ftruncate(GROW) didn't fail as expected\n");
			abort();
			}

			r = fallocate(fd,
			0,
			0,
			MFD_DEF_SIZE * 4);
			if (r >= 0) {
			printf("fallocate(ALLOC) didn't fail as expected\n");
			abort();
			}
			}

			static void mfd_assert_grow_write(int fd)
			{
			static char buf[MFD_DEF_SIZE * 8];
			ssize_t l;

			l = pwrite(fd, buf, sizeof(buf), 0);
			if (l != sizeof(buf)) {
			printf("pwrite() failed: %m\n");
			abort();
			}

			mfd_assert_size(fd, MFD_DEF_SIZE * 8);
			}

			static void mfd_fail_grow_write(int fd)
			{
			static char buf[MFD_DEF_SIZE * 8];
			ssize_t l;

			l = pwrite(fd, buf, sizeof(buf), 0);
			if (l == sizeof(buf)) {
			printf("pwrite() didn't fail as expected\n");
			abort();
			}
			}

			static int idle_thread_fn(void *arg)
			{
			sigset_t set;
			int sig;

			/* dummy waiter; SIGTERM terminates us anyway */
			sigemptyset(&set);
			sigaddset(&set, SIGTERM);
			sigwait(&set, &sig);

			return 0;
			}

			static pid_t spawn_idle_thread(unsigned int flags)
			{
			uint8_t *stack;
			pid_t pid;

			stack = malloc(STACK_SIZE);
			if (!stack) {
			printf("malloc(STACK_SIZE) failed: %m\n");
			abort();
			}

			pid = clone(idle_thread_fn,
			stack + STACK_SIZE,
			SIGCHLD \| flags,
			NULL);
			if (pid < 0) {
			printf("clone() failed: %m\n");
			abort();
			}

			return pid;
			}

			static void join_idle_thread(pid_t pid)
			{
			kill(pid, SIGTERM);
			waitpid(pid, NULL, 0);
			}

			/*
			* Test memfd_create() syscall
			* Verify syscall-argument validation, including name checks, flag validation
			* and more.
			*/
			static void test_create(void)
			{
			char buf[2048];
			int fd;

			/* test NULL name */
			mfd_fail_new(NULL, 0);

			/* test over-long name (not zero-terminated) */
			memset(buf, 0xff, sizeof(buf));
			mfd_fail_new(buf, 0);

			/* test over-long zero-terminated name */
			memset(buf, 0xff, sizeof(buf));
			buf[sizeof(buf) - 1] = 0;
			mfd_fail_new(buf, 0);

			/* verify "" is a valid name */
			fd = mfd_assert_new("", 0, 0);
			close(fd);

			/* verify invalid O_* open flags */
			mfd_fail_new("", 0x0100);
			mfd_fail_new("", ~MFD_CLOEXEC);
			mfd_fail_new("", ~MFD_ALLOW_SEALING);
			mfd_fail_new("", ~0);
			mfd_fail_new("", 0x80000000U);

			/* verify MFD_CLOEXEC is allowed */
			fd = mfd_assert_new("", 0, MFD_CLOEXEC);
			close(fd);

			/* verify MFD_ALLOW_SEALING is allowed */
			fd = mfd_assert_new("", 0, MFD_ALLOW_SEALING);
			close(fd);

			/* verify MFD_ALLOW_SEALING \| MFD_CLOEXEC is allowed */
			fd = mfd_assert_new("", 0, MFD_ALLOW_SEALING \| MFD_CLOEXEC);
			close(fd);
			}

			/*
			* Test basic sealing
			* A very basic sealing test to see whether setting/retrieving seals works.
			*/
			static void test_basic(void)
			{
			int fd;

			fd = mfd_assert_new("kern_memfd_basic",
			MFD_DEF_SIZE,
			MFD_CLOEXEC \| MFD_ALLOW_SEALING);

			/* add basic seals */
			mfd_assert_has_seals(fd, 0);
			mfd_assert_add_seals(fd, F_SEAL_SHRINK \|
			F_SEAL_WRITE);
			mfd_assert_has_seals(fd, F_SEAL_SHRINK \|
			F_SEAL_WRITE);

			/* add them again */
			mfd_assert_add_seals(fd, F_SEAL_SHRINK \|
			F_SEAL_WRITE);
			mfd_assert_has_seals(fd, F_SEAL_SHRINK \|
			F_SEAL_WRITE);

			/* add more seals and seal against sealing */
			mfd_assert_add_seals(fd, F_SEAL_GROW \| F_SEAL_SEAL);
			mfd_assert_has_seals(fd, F_SEAL_SHRINK \|
			F_SEAL_GROW \|
			F_SEAL_WRITE \|
			F_SEAL_SEAL);

			/* verify that sealing no longer works */
			mfd_fail_add_seals(fd, F_SEAL_GROW);
			mfd_fail_add_seals(fd, 0);

			close(fd);

			/* verify sealing does not work without MFD_ALLOW_SEALING */
			fd = mfd_assert_new("kern_memfd_basic",
			MFD_DEF_SIZE,
			MFD_CLOEXEC);
			mfd_assert_has_seals(fd, F_SEAL_SEAL);
			mfd_fail_add_seals(fd, F_SEAL_SHRINK \|
			F_SEAL_GROW \|
			F_SEAL_WRITE);
			mfd_assert_has_seals(fd, F_SEAL_SEAL);
			close(fd);
			}

			/*
			* Test SEAL_WRITE
			* Test whether SEAL_WRITE actually prevents modifications.
			*/
			static void test_seal_write(void)
			{
			int fd;

			fd = mfd_assert_new("kern_memfd_seal_write",
			MFD_DEF_SIZE,
			MFD_CLOEXEC \| MFD_ALLOW_SEALING);
			mfd_assert_has_seals(fd, 0);
			mfd_assert_add_seals(fd, F_SEAL_WRITE);
			mfd_assert_has_seals(fd, F_SEAL_WRITE);

			mfd_assert_read(fd);
			mfd_fail_write(fd);
			mfd_assert_shrink(fd);
			mfd_assert_grow(fd);
			mfd_fail_grow_write(fd);

			close(fd);
			}

			/*
			* Test SEAL_SHRINK
			* Test whether SEAL_SHRINK actually prevents shrinking
			*/
			static void test_seal_shrink(void)
			{
			int fd;

			fd = mfd_assert_new("kern_memfd_seal_shrink",
			MFD_DEF_SIZE,
			MFD_CLOEXEC \| MFD_ALLOW_SEALING);
			mfd_assert_has_seals(fd, 0);
			mfd_assert_add_seals(fd, F_SEAL_SHRINK);
			mfd_assert_has_seals(fd, F_SEAL_SHRINK);

			mfd_assert_read(fd);
			mfd_assert_write(fd);
			mfd_fail_shrink(fd);
			mfd_assert_grow(fd);
			mfd_assert_grow_write(fd);

			close(fd);
			}

			/*
			* Test SEAL_GROW
			* Test whether SEAL_GROW actually prevents growing
			*/
			static void test_seal_grow(void)
			{
			int fd;

			fd = mfd_assert_new("kern_memfd_seal_grow",
			MFD_DEF_SIZE,
			MFD_CLOEXEC \| MFD_ALLOW_SEALING);
			mfd_assert_has_seals(fd, 0);
			mfd_assert_add_seals(fd, F_SEAL_GROW);
			mfd_assert_has_seals(fd, F_SEAL_GROW);

			mfd_assert_read(fd);
			mfd_assert_write(fd);
			mfd_assert_shrink(fd);
			mfd_fail_grow(fd);
			mfd_fail_grow_write(fd);

			close(fd);
			}

			/*
			* Test SEAL_SHRINK \| SEAL_GROW
			* Test whether SEAL_SHRINK \| SEAL_GROW actually prevents resizing
			*/
			static void test_seal_resize(void)
			{
			int fd;

			fd = mfd_assert_new("kern_memfd_seal_resize",
			MFD_DEF_SIZE,
			MFD_CLOEXEC \| MFD_ALLOW_SEALING);
			mfd_assert_has_seals(fd, 0);
			mfd_assert_add_seals(fd, F_SEAL_SHRINK \| F_SEAL_GROW);
			mfd_assert_has_seals(fd, F_SEAL_SHRINK \| F_SEAL_GROW);

			mfd_assert_read(fd);
			mfd_assert_write(fd);
			mfd_fail_shrink(fd);
			mfd_fail_grow(fd);
			mfd_fail_grow_write(fd);

			close(fd);
			}

			/*
			* Test sharing via dup()
			* Test that seals are shared between dupped FDs and they're all equal.
			*/
			static void test_share_dup(void)
			{
			int fd, fd2;

			fd = mfd_assert_new("kern_memfd_share_dup",
			MFD_DEF_SIZE,
			MFD_CLOEXEC \| MFD_ALLOW_SEALING);
			mfd_assert_has_seals(fd, 0);

			fd2 = mfd_assert_dup(fd);
			mfd_assert_has_seals(fd2, 0);

			mfd_assert_add_seals(fd, F_SEAL_WRITE);
			mfd_assert_has_seals(fd, F_SEAL_WRITE);
			mfd_assert_has_seals(fd2, F_SEAL_WRITE);

			mfd_assert_add_seals(fd2, F_SEAL_SHRINK);
			mfd_assert_has_seals(fd, F_SEAL_WRITE \| F_SEAL_SHRINK);
			mfd_assert_has_seals(fd2, F_SEAL_WRITE \| F_SEAL_SHRINK);

			mfd_assert_add_seals(fd, F_SEAL_SEAL);
			mfd_assert_has_seals(fd, F_SEAL_WRITE \| F_SEAL_SHRINK \| F_SEAL_SEAL);
			mfd_assert_has_seals(fd2, F_SEAL_WRITE \| F_SEAL_SHRINK \| F_SEAL_SEAL);

			mfd_fail_add_seals(fd, F_SEAL_GROW);
			mfd_fail_add_seals(fd2, F_SEAL_GROW);
			mfd_fail_add_seals(fd, F_SEAL_SEAL);
			mfd_fail_add_seals(fd2, F_SEAL_SEAL);

			close(fd2);

			mfd_fail_add_seals(fd, F_SEAL_GROW);
			close(fd);
			}

			/*
			* Test sealing with active mmap()s
			* Modifying seals is only allowed if no other mmap() refs exist.
			*/
			static void test_share_mmap(void)
			{
			int fd;
			void *p;

			fd = mfd_assert_new("kern_memfd_share_mmap",
			MFD_DEF_SIZE,
			MFD_CLOEXEC \| MFD_ALLOW_SEALING);
			mfd_assert_has_seals(fd, 0);

			/* shared/writable ref prevents sealing WRITE, but allows others */
			p = mfd_assert_mmap_shared(fd);
			mfd_fail_add_seals(fd, F_SEAL_WRITE);
			mfd_assert_has_seals(fd, 0);
			mfd_assert_add_seals(fd, F_SEAL_SHRINK);
			mfd_assert_has_seals(fd, F_SEAL_SHRINK);
			munmap(p, MFD_DEF_SIZE);

			/* readable ref allows sealing */
			p = mfd_assert_mmap_private(fd);
			mfd_assert_add_seals(fd, F_SEAL_WRITE);
			mfd_assert_has_seals(fd, F_SEAL_WRITE \| F_SEAL_SHRINK);
			munmap(p, MFD_DEF_SIZE);

			close(fd);
			}

			/*
			* Test sealing with open(/proc/self/fd/%d)
			* Via /proc we can get access to a separate file-context for the same memfd.
			* This is not like dup(), but like a real separate open(). Make sure the
			* semantics are as expected and we correctly check for RDONLY / WRONLY / RDWR.
			*/
			static void test_share_open(void)
			{
			int fd, fd2;

			fd = mfd_assert_new("kern_memfd_share_open",
			MFD_DEF_SIZE,
			MFD_CLOEXEC \| MFD_ALLOW_SEALING);
			mfd_assert_has_seals(fd, 0);

			fd2 = mfd_assert_open(fd, O_RDWR, 0);
			mfd_assert_add_seals(fd, F_SEAL_WRITE);
			mfd_assert_has_seals(fd, F_SEAL_WRITE);
			mfd_assert_has_seals(fd2, F_SEAL_WRITE);

			mfd_assert_add_seals(fd2, F_SEAL_SHRINK);
			mfd_assert_has_seals(fd, F_SEAL_WRITE \| F_SEAL_SHRINK);
			mfd_assert_has_seals(fd2, F_SEAL_WRITE \| F_SEAL_SHRINK);

			close(fd);
			fd = mfd_assert_open(fd2, O_RDONLY, 0);

			mfd_fail_add_seals(fd, F_SEAL_SEAL);
			mfd_assert_has_seals(fd, F_SEAL_WRITE \| F_SEAL_SHRINK);
			mfd_assert_has_seals(fd2, F_SEAL_WRITE \| F_SEAL_SHRINK);

			close(fd2);
			fd2 = mfd_assert_open(fd, O_RDWR, 0);

			mfd_assert_add_seals(fd2, F_SEAL_SEAL);
			mfd_assert_has_seals(fd, F_SEAL_WRITE \| F_SEAL_SHRINK \| F_SEAL_SEAL);
			mfd_assert_has_seals(fd2, F_SEAL_WRITE \| F_SEAL_SHRINK \| F_SEAL_SEAL);

			close(fd2);
			close(fd);
			}

			/*
			* Test sharing via fork()
			* Test whether seal-modifications work as expected with forked childs.
			*/
			static void test_share_fork(void)
			{
			int fd;
			pid_t pid;

			fd = mfd_assert_new("kern_memfd_share_fork",
			MFD_DEF_SIZE,
			MFD_CLOEXEC \| MFD_ALLOW_SEALING);
			mfd_assert_has_seals(fd, 0);

			pid = spawn_idle_thread(0);
			mfd_assert_add_seals(fd, F_SEAL_SEAL);
			mfd_assert_has_seals(fd, F_SEAL_SEAL);

			mfd_fail_add_seals(fd, F_SEAL_WRITE);
			mfd_assert_has_seals(fd, F_SEAL_SEAL);

			join_idle_thread(pid);

			mfd_fail_add_seals(fd, F_SEAL_WRITE);
			mfd_assert_has_seals(fd, F_SEAL_SEAL);

			close(fd);
			}

			int main(int argc, char **argv)
			{
			pid_t pid;

			printf("memfd: CREATE\n");
			test_create();
			printf("memfd: BASIC\n");
			test_basic();

			printf("memfd: SEAL-WRITE\n");
			test_seal_write();
			printf("memfd: SEAL-SHRINK\n");
			test_seal_shrink();
			printf("memfd: SEAL-GROW\n");
			test_seal_grow();
			printf("memfd: SEAL-RESIZE\n");
			test_seal_resize();

			printf("memfd: SHARE-DUP\n");
			test_share_dup();
			printf("memfd: SHARE-MMAP\n");
			test_share_mmap();
			printf("memfd: SHARE-OPEN\n");
			test_share_open();
			printf("memfd: SHARE-FORK\n");
			test_share_fork();

			/* Run test-suite in a multi-threaded environment with a shared
			* file-table. */
			pid = spawn_idle_thread(CLONE_FILES \| CLONE_FS \| CLONE_VM);
			printf("memfd: SHARE-DUP (shared file-table)\n");
			test_share_dup();
			printf("memfd: SHARE-MMAP (shared file-table)\n");
			test_share_mmap();
			printf("memfd: SHARE-OPEN (shared file-table)\n");
			test_share_open();
			printf("memfd: SHARE-FORK (shared file-table)\n");
			test_share_fork();
			join_idle_thread(pid);

			printf("memfd: DONE\n");

			return 0;
			}

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