Some basic tests to verify sealing on memfds works as expected and
guarantees the advertised semantics.
Signed-off-by: David Herrmann <dh.herrmann@xxxxxxxxx>
---
tools/testing/selftests/Makefile | 1 +
tools/testing/selftests/memfd/.gitignore | 2 +
tools/testing/selftests/memfd/Makefile | 29 +
tools/testing/selftests/memfd/memfd_test.c | 972 +++++++++++++++++++++++++++++
4 files changed, 1004 insertions(+)
create mode 100644 tools/testing/selftests/memfd/.gitignore
create mode 100644 tools/testing/selftests/memfd/Makefile
create mode 100644 tools/testing/selftests/memfd/memfd_test.c
diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 32487ed..c57325a 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -2,6 +2,7 @@ TARGETS = breakpoints
TARGETS += cpu-hotplug
TARGETS += efivarfs
TARGETS += kcmp
+TARGETS += memfd
TARGETS += memory-hotplug
TARGETS += mqueue
TARGETS += net
diff --git a/tools/testing/selftests/memfd/.gitignore b/tools/testing/selftests/memfd/.gitignore
new file mode 100644
index 0000000..bcc8ee2
--- /dev/null
+++ b/tools/testing/selftests/memfd/.gitignore
@@ -0,0 +1,2 @@
+memfd_test
+memfd-test-file
diff --git a/tools/testing/selftests/memfd/Makefile b/tools/testing/selftests/memfd/Makefile
new file mode 100644
index 0000000..36653b9
--- /dev/null
+++ b/tools/testing/selftests/memfd/Makefile
@@ -0,0 +1,29 @@
+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
diff --git a/tools/testing/selftests/memfd/memfd_test.c b/tools/testing/selftests/memfd/memfd_test.c
new file mode 100644
index 0000000..41bac6f
--- /dev/null
+++ b/tools/testing/selftests/memfd/memfd_test.c
@@ -0,0 +1,972 @@
+#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,
+ __u64 size,
+ __u64 flags)
+{
+ return syscall(__NR_memfd_create, name, size, flags);
+}
+
+static int mfd_assert_new(const char *name, __u64 sz, __u64 flags)
+{
+ int r;
+
+ r = sys_memfd_create(name, sz, flags);
+ if (r < 0) {
+ printf("memfd_create(\"%s\", %llu, %llu) failed: %m\n",
+ name, (unsigned long long)sz,
+ (unsigned long long)flags);
+ abort();
+ }
+
+ return r;
+}
+
+static void mfd_fail_new(const char *name, __u64 size, __u64 flags)
+{
+ int r;
+
+ r = sys_memfd_create(name, size, flags);
+ if (r >= 0) {
+ printf("memfd_create(\"%s\", %llu, %llu) succeeded, but failure expected\n",
+ name, (unsigned long long)size,
+ (unsigned long long)flags);
+ close(r);
+ abort();
+ }
+}
+
+static __u64 mfd_assert_get_seals(int fd)
+{
+ long r;
+
+ r = fcntl(fd, SHMEM_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_set_seals(int fd, __u64 seals)
+{
+ long r;
+ __u64 s;
+
+ s = mfd_assert_get_seals(fd);
+ r = fcntl(fd, SHMEM_SET_SEALS, seals);
+ if (r < 0) {
+ printf("SET_SEALS(%d, %llu -> %llu) failed: %m\n",
+ fd, (unsigned long long)s, (unsigned long long)seals);
+ abort();
+ }
+}
+
+static void mfd_fail_set_seals(int fd, __u64 seals)
+{
+ long r;
+ __u64 s;
+
+ s = mfd_assert_get_seals(fd);
+ r = fcntl(fd, SHMEM_SET_SEALS, seals);
+ if (r >= 0) {
+ printf("SET_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 is not allowed */
+ p = mmap(NULL,
+ MFD_DEF_SIZE,
+ PROT_READ,
+ MAP_SHARED,
+ fd,
+ 0);
+ if (p != MAP_FAILED) {
+ printf("mmap() 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(void)
+{
+ 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,
+ CLONE_FILES | CLONE_FS | CLONE_VM | SIGCHLD,
+ 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);
+}
+
+static pid_t spawn_idle_proc(void)
+{
+ pid_t pid;
+ sigset_t set;
+ int sig;
+
+ pid = fork();
+ if (pid < 0) {
+ printf("fork() failed: %m\n");
+ abort();
+ } else if (!pid) {
+ /* dummy waiter; SIGTERM terminates us anyway */
+ sigemptyset(&set);
+ sigaddset(&set, SIGTERM);
+ sigwait(&set, &sig);
+ exit(0);
+ }
+
+ return pid;
+}
+
+static void join_idle_proc(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, 0);
+
+ /* test over-long name (not zero-terminated) */
+ memset(buf, 0xff, sizeof(buf));
+ mfd_fail_new(buf, 0, 0);
+
+ /* test over-long zero-terminated name */
+ memset(buf, 0xff, sizeof(buf));
+ buf[sizeof(buf) - 1] = 0;
+ mfd_fail_new(buf, 0, 0);
+
+ /* verify "" is a valid name */
+ fd = mfd_assert_new("", 0, 0);
+ close(fd);
+
+ /* verify invalid O_* open flags */
+ mfd_fail_new("", 0, 0x0100);
+ mfd_fail_new("", 0, ~MFD_CLOEXEC);
+ mfd_fail_new("", 0, ~0);
+ mfd_fail_new("", 0, 0x8000000000000000ULL);
+
+ /* verify MFD_CLOEXEC is allowed */
+ fd = mfd_assert_new("", 0, 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_assert_has_seals(fd, 0);
+ mfd_assert_set_seals(fd, SHMEM_SEAL_SHRINK |
+ SHMEM_SEAL_GROW |
+ SHMEM_SEAL_WRITE);
+ mfd_assert_has_seals(fd, SHMEM_SEAL_SHRINK |
+ SHMEM_SEAL_GROW |
+ SHMEM_SEAL_WRITE);
+ 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_assert_has_seals(fd, 0);
+ mfd_assert_set_seals(fd, SHMEM_SEAL_WRITE);
+ mfd_assert_has_seals(fd, SHMEM_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_assert_has_seals(fd, 0);
+ mfd_assert_set_seals(fd, SHMEM_SEAL_SHRINK);
+ mfd_assert_has_seals(fd, SHMEM_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_assert_has_seals(fd, 0);
+ mfd_assert_set_seals(fd, SHMEM_SEAL_GROW);
+ mfd_assert_has_seals(fd, SHMEM_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_assert_has_seals(fd, 0);
+ mfd_assert_set_seals(fd, SHMEM_SEAL_SHRINK | SHMEM_SEAL_GROW);
+ mfd_assert_has_seals(fd, SHMEM_SEAL_SHRINK | SHMEM_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 whether seal-modifications are correctly discarded if multiple FDs for
+ * the same file exist.
+ */
+static void test_share_dup(void)
+{
+ int fd, fd2;
+
+ fd = mfd_assert_new("kern_memfd_share_dup",
+ MFD_DEF_SIZE,
+ MFD_CLOEXEC);
+ mfd_assert_has_seals(fd, 0);
+
+ fd2 = mfd_assert_dup(fd);
+ mfd_assert_set_seals(fd, SHMEM_SEAL_WRITE);
+ mfd_assert_has_seals(fd, SHMEM_SEAL_WRITE);
+
+ mfd_fail_set_seals(fd, SHMEM_SEAL_WRITE | SHMEM_SEAL_SHRINK);
+ mfd_assert_has_seals(fd, SHMEM_SEAL_WRITE);
+
+ mfd_fail_set_seals(fd, SHMEM_SEAL_SHRINK);
+ mfd_assert_has_seals(fd, SHMEM_SEAL_WRITE);
+
+ mfd_fail_set_seals(fd, 0);
+ mfd_assert_has_seals(fd, SHMEM_SEAL_WRITE);
+
+ close(fd2);
+
+ mfd_assert_set_seals(fd, SHMEM_SEAL_WRITE | SHMEM_SEAL_SHRINK);
+ mfd_assert_has_seals(fd, SHMEM_SEAL_WRITE | SHMEM_SEAL_SHRINK);
+
+ mfd_assert_set_seals(fd, SHMEM_SEAL_GROW);
+ mfd_assert_has_seals(fd, SHMEM_SEAL_GROW);
+
+ mfd_assert_set_seals(fd, 0);
+ mfd_assert_has_seals(fd, 0);
+
+ /* try again but switch FDs to test that they're equal */
+
+ fd2 = mfd_assert_dup(fd);
+ mfd_assert_set_seals(fd2, SHMEM_SEAL_WRITE);
+ mfd_assert_has_seals(fd2, SHMEM_SEAL_WRITE);
+
+ mfd_fail_set_seals(fd2, SHMEM_SEAL_WRITE | SHMEM_SEAL_SHRINK);
+ mfd_assert_has_seals(fd2, SHMEM_SEAL_WRITE);
+
+ mfd_fail_set_seals(fd2, SHMEM_SEAL_SHRINK);
+ mfd_assert_has_seals(fd2, SHMEM_SEAL_WRITE);
+
+ mfd_fail_set_seals(fd2, 0);
+ mfd_assert_has_seals(fd2, SHMEM_SEAL_WRITE);
+
+ close(fd);
+
+ mfd_assert_set_seals(fd2, SHMEM_SEAL_WRITE | SHMEM_SEAL_SHRINK);
+ mfd_assert_has_seals(fd2, SHMEM_SEAL_WRITE | SHMEM_SEAL_SHRINK);
+
+ mfd_assert_set_seals(fd2, SHMEM_SEAL_GROW);
+ mfd_assert_has_seals(fd2, SHMEM_SEAL_GROW);
+
+ mfd_assert_set_seals(fd2, 0);
+ mfd_assert_has_seals(fd2, 0);
+
+ close(fd2);
+}
+
+/*
+ * Test sealing with active mmap()s
+ * Modifying seals is only allowed if no other mmap() refs exist, except for
+ * initial sealing, which allows read-only mappings. Test for the different
+ * combinations here.
+ */
+static void test_share_mmap(void)
+{
+ int fd;
+ void *p;
+
+ fd = mfd_assert_new("kern_memfd_share_mmap",
+ MFD_DEF_SIZE,
+ MFD_CLOEXEC);
+ mfd_assert_has_seals(fd, 0);
+
+ /* shared/writable ref prevents sealing */
+ p = mfd_assert_mmap_shared(fd);
+ mfd_fail_set_seals(fd, SHMEM_SEAL_SHRINK);
+ mfd_assert_has_seals(fd, 0);
+ munmap(p, MFD_DEF_SIZE);
+
+ /* readable ref allows initial sealing, but prevents modifications */
+ p = mfd_assert_mmap_private(fd);
+ mfd_assert_set_seals(fd, SHMEM_SEAL_SHRINK);
+ mfd_assert_has_seals(fd, SHMEM_SEAL_SHRINK);
+ mfd_fail_set_seals(fd, SHMEM_SEAL_WRITE);
+ mfd_assert_has_seals(fd, SHMEM_SEAL_SHRINK);
+ munmap(p, MFD_DEF_SIZE);
+
+ /* dropping all additional refs allows modifications again */
+ mfd_assert_set_seals(fd, 0);
+ mfd_assert_has_seals(fd, 0);
+
+ 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_assert_has_seals(fd, 0);
+
+ fd2 = mfd_assert_open(fd, O_RDONLY, 0);
+ mfd_assert_set_seals(fd, SHMEM_SEAL_WRITE);
+ mfd_assert_has_seals(fd, SHMEM_SEAL_WRITE);
+
+ mfd_fail_set_seals(fd, SHMEM_SEAL_WRITE | SHMEM_SEAL_SHRINK);
+ mfd_assert_has_seals(fd, SHMEM_SEAL_WRITE);
+
+ mfd_fail_set_seals(fd, SHMEM_SEAL_SHRINK);
+ mfd_assert_has_seals(fd, SHMEM_SEAL_WRITE);
+
+ mfd_fail_set_seals(fd, 0);
+ mfd_assert_has_seals(fd, SHMEM_SEAL_WRITE);
+
+ close(fd2);
+
+ mfd_assert_set_seals(fd, SHMEM_SEAL_WRITE | SHMEM_SEAL_SHRINK);
+ mfd_assert_has_seals(fd, SHMEM_SEAL_WRITE | SHMEM_SEAL_SHRINK);
+
+ mfd_assert_set_seals(fd, SHMEM_SEAL_GROW);
+ mfd_assert_has_seals(fd, SHMEM_SEAL_GROW);
+
+ mfd_assert_set_seals(fd, 0);
+ mfd_assert_has_seals(fd, 0);
+
+ /* test that RDONLY doesn't allow setting seals, even if exclusive */
+
+ fd2 = mfd_assert_open(fd, O_RDONLY, 0);
+ mfd_fail_set_seals(fd2, SHMEM_SEAL_WRITE);
+ mfd_assert_has_seals(fd2, 0);
+
+ close(fd);
+
+ mfd_fail_set_seals(fd2, SHMEM_SEAL_WRITE);
+ mfd_assert_has_seals(fd2, 0);
+
+ close(fd2);
+
+ /* same again but with writable open */
+
+ fd = mfd_assert_new("kern_memfd_share_open",
+ MFD_DEF_SIZE,
+ MFD_CLOEXEC);
+ mfd_assert_has_seals(fd, 0);
+
+ fd2 = mfd_assert_open(fd, O_RDWR, 0);
+ mfd_assert_set_seals(fd2, SHMEM_SEAL_WRITE);
+ mfd_assert_has_seals(fd2, SHMEM_SEAL_WRITE);
+
+ close(fd);
+
+ mfd_assert_set_seals(fd2, SHMEM_SEAL_WRITE | SHMEM_SEAL_SHRINK);
+ mfd_assert_has_seals(fd2, SHMEM_SEAL_WRITE | SHMEM_SEAL_SHRINK);
+
+ mfd_assert_set_seals(fd2, SHMEM_SEAL_GROW);
+ mfd_assert_has_seals(fd2, SHMEM_SEAL_GROW);
+
+ mfd_assert_set_seals(fd2, 0);
+ mfd_assert_has_seals(fd2, 0);
+
+ close(fd2);
+}
+
+/*
+ * Test sharing via fork()
+ * Test whether seal-modifications are correctly discarded if multiple FDs for
+ * the same file exist.
+ */
+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_assert_has_seals(fd, 0);
+
+ pid = spawn_idle_proc();
+ mfd_assert_set_seals(fd, SHMEM_SEAL_WRITE);
+ mfd_assert_has_seals(fd, SHMEM_SEAL_WRITE);
+
+ mfd_fail_set_seals(fd, SHMEM_SEAL_WRITE | SHMEM_SEAL_SHRINK);
+ mfd_assert_has_seals(fd, SHMEM_SEAL_WRITE);
+
+ mfd_fail_set_seals(fd, SHMEM_SEAL_SHRINK);
+ mfd_assert_has_seals(fd, SHMEM_SEAL_WRITE);
+
+ mfd_fail_set_seals(fd, 0);
+ mfd_assert_has_seals(fd, SHMEM_SEAL_WRITE);
+
+ join_idle_proc(pid);
+
+ mfd_assert_set_seals(fd, SHMEM_SEAL_WRITE | SHMEM_SEAL_SHRINK);
+ mfd_assert_has_seals(fd, SHMEM_SEAL_WRITE | SHMEM_SEAL_SHRINK);
+
+ mfd_assert_set_seals(fd, SHMEM_SEAL_GROW);
+ mfd_assert_has_seals(fd, SHMEM_SEAL_GROW);
+
+ mfd_assert_set_seals(fd, 0);
+ mfd_assert_has_seals(fd, 0);
+
+ 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. This triggers the slow-path in fdget() in the kernel. */
+ pid = spawn_idle_thread();
+ 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;
+}
--
1.9.0
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