Re: [PATCH v4 2/2] tests: add move_mount(MOVE_MOUNT_SET_GROUP) selftest
From: Pavel Tikhomirov
Date: Thu Jul 15 2021 - 05:51:23 EST
Adding everybody back to CC, sorry I accidentally dropped all CC in the
2/2 selftest patch.
On 14.07.2021 19:10, Pavel Tikhomirov wrote:
Add a simple selftest for a move_mount(MOVE_MOUNT_SET_GROUP). This tests
that one can copy sharing from one mount from nested mntns with nested
userns owner to another mount from other nested mntns with other nested
userns owner while in their parent userns.
TAP version 13
1..1
# Starting 1 tests from 2 test cases.
# RUN move_mount_set_group.complex_sharing_copying ...
# OK move_mount_set_group.complex_sharing_copying
ok 1 move_mount_set_group.complex_sharing_copying
# PASSED: 1 / 1 tests passed.
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
Signed-off-by: Pavel Tikhomirov <ptikhomirov@xxxxxxxxxxxxx>
---
I took mount_setattr test as an example, I'm not to experienced in
selftests so hope I'm not doing something wrong here.
I implemented a testcase having in mind the way how I plan to use this
interface in criu, so it's not simply copying sharing between two nearby
mounts but it also adds some userns+mntns-es to test cross-namespace
copying.
Note: One can also test MOVE_MOUNT_SET_GROUP via zdtm tests on criu
mount-v2 POC: https://github.com/Snorch/criu/commits/mount-v2-poc
v3: add some test
---
tools/testing/selftests/Makefile | 1 +
.../selftests/move_mount_set_group/.gitignore | 1 +
.../selftests/move_mount_set_group/Makefile | 7 +
.../selftests/move_mount_set_group/config | 1 +
.../move_mount_set_group_test.c | 375 ++++++++++++++++++
5 files changed, 385 insertions(+)
create mode 100644 tools/testing/selftests/move_mount_set_group/.gitignore
create mode 100644 tools/testing/selftests/move_mount_set_group/Makefile
create mode 100644 tools/testing/selftests/move_mount_set_group/config
create mode 100644 tools/testing/selftests/move_mount_set_group/move_mount_set_group_test.c
diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index fb010a35d61a..dd0388eab94d 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -35,6 +35,7 @@ TARGETS += memory-hotplug
TARGETS += mincore
TARGETS += mount
TARGETS += mount_setattr
+TARGETS += move_mount_set_group
TARGETS += mqueue
TARGETS += nci
TARGETS += net
diff --git a/tools/testing/selftests/move_mount_set_group/.gitignore b/tools/testing/selftests/move_mount_set_group/.gitignore
new file mode 100644
index 000000000000..f5e339268720
--- /dev/null
+++ b/tools/testing/selftests/move_mount_set_group/.gitignore
@@ -0,0 +1 @@
+move_mount_set_group_test
diff --git a/tools/testing/selftests/move_mount_set_group/Makefile b/tools/testing/selftests/move_mount_set_group/Makefile
new file mode 100644
index 000000000000..80c2d86812b0
--- /dev/null
+++ b/tools/testing/selftests/move_mount_set_group/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0
+# Makefile for mount selftests.
+CFLAGS = -g -I../../../../usr/include/ -Wall -O2
+
+TEST_GEN_FILES += move_mount_set_group_test
+
+include ../lib.mk
diff --git a/tools/testing/selftests/move_mount_set_group/config b/tools/testing/selftests/move_mount_set_group/config
new file mode 100644
index 000000000000..416bd53ce982
--- /dev/null
+++ b/tools/testing/selftests/move_mount_set_group/config
@@ -0,0 +1 @@
+CONFIG_USER_NS=y
diff --git a/tools/testing/selftests/move_mount_set_group/move_mount_set_group_test.c b/tools/testing/selftests/move_mount_set_group/move_mount_set_group_test.c
new file mode 100644
index 000000000000..ca0c0c2db991
--- /dev/null
+++ b/tools/testing/selftests/move_mount_set_group/move_mount_set_group_test.c
@@ -0,0 +1,375 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <sched.h>
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/mount.h>
+#include <sys/wait.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <stdarg.h>
+#include <sys/syscall.h>
+
+#include "../kselftest_harness.h"
+
+#ifndef CLONE_NEWNS
+#define CLONE_NEWNS 0x00020000
+#endif
+
+#ifndef CLONE_NEWUSER
+#define CLONE_NEWUSER 0x10000000
+#endif
+
+#ifndef MS_SHARED
+#define MS_SHARED (1 << 20)
+#endif
+
+#ifndef MS_PRIVATE
+#define MS_PRIVATE (1<<18)
+#endif
+
+#ifndef MOVE_MOUNT_SET_GROUP
+#define MOVE_MOUNT_SET_GROUP 0x00000100
+#endif
+
+#ifndef MOVE_MOUNT_F_EMPTY_PATH
+#define MOVE_MOUNT_F_EMPTY_PATH 0x00000004
+#endif
+
+#ifndef MOVE_MOUNT_T_EMPTY_PATH
+#define MOVE_MOUNT_T_EMPTY_PATH 0x00000040
+#endif
+
+static ssize_t write_nointr(int fd, const void *buf, size_t count)
+{
+ ssize_t ret;
+
+ do {
+ ret = write(fd, buf, count);
+ } while (ret < 0 && errno == EINTR);
+
+ return ret;
+}
+
+static int write_file(const char *path, const void *buf, size_t count)
+{
+ int fd;
+ ssize_t ret;
+
+ fd = open(path, O_WRONLY | O_CLOEXEC | O_NOCTTY | O_NOFOLLOW);
+ if (fd < 0)
+ return -1;
+
+ ret = write_nointr(fd, buf, count);
+ close(fd);
+ if (ret < 0 || (size_t)ret != count)
+ return -1;
+
+ return 0;
+}
+
+static int create_and_enter_userns(void)
+{
+ uid_t uid;
+ gid_t gid;
+ char map[100];
+
+ uid = getuid();
+ gid = getgid();
+
+ if (unshare(CLONE_NEWUSER))
+ return -1;
+
+ if (write_file("/proc/self/setgroups", "deny", sizeof("deny") - 1) &&
+ errno != ENOENT)
+ return -1;
+
+ snprintf(map, sizeof(map), "0 %d 1", uid);
+ if (write_file("/proc/self/uid_map", map, strlen(map)))
+ return -1;
+
+
+ snprintf(map, sizeof(map), "0 %d 1", gid);
+ if (write_file("/proc/self/gid_map", map, strlen(map)))
+ return -1;
+
+ if (setgid(0))
+ return -1;
+
+ if (setuid(0))
+ return -1;
+
+ return 0;
+}
+
+static int prepare_unpriv_mountns(void)
+{
+ if (create_and_enter_userns())
+ return -1;
+
+ if (unshare(CLONE_NEWNS))
+ return -1;
+
+ if (mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, 0))
+ return -1;
+
+ return 0;
+}
+
+static char *get_field(char *src, int nfields)
+{
+ int i;
+ char *p = src;
+
+ for (i = 0; i < nfields; i++) {
+ while (*p && *p != ' ' && *p != '\t')
+ p++;
+
+ if (!*p)
+ break;
+
+ p++;
+ }
+
+ return p;
+}
+
+static void null_endofword(char *word)
+{
+ while (*word && *word != ' ' && *word != '\t')
+ word++;
+ *word = '\0';
+}
+
+static bool is_shared_mount(const char *path)
+{
+ size_t len = 0;
+ char *line = NULL;
+ FILE *f = NULL;
+
+ f = fopen("/proc/self/mountinfo", "re");
+ if (!f)
+ return false;
+
+ while (getline(&line, &len, f) != -1) {
+ char *opts, *target;
+
+ target = get_field(line, 4);
+ if (!target)
+ continue;
+
+ opts = get_field(target, 2);
+ if (!opts)
+ continue;
+
+ null_endofword(target);
+
+ if (strcmp(target, path) != 0)
+ continue;
+
+ null_endofword(opts);
+ if (strstr(opts, "shared:"))
+ return true;
+ }
+
+ free(line);
+ fclose(f);
+
+ return false;
+}
+
+/* Attempt to de-conflict with the selftests tree. */
+#ifndef SKIP
+#define SKIP(s, ...) XFAIL(s, ##__VA_ARGS__)
+#endif
+
+#define SET_GROUP_FROM "/tmp/move_mount_set_group_supported_from"
+#define SET_GROUP_TO "/tmp/move_mount_set_group_supported_to"
+
+static int move_mount_set_group_supported(void)
+{
+ int ret;
+
+ if (mount("testing", "/tmp", "tmpfs", MS_NOATIME | MS_NODEV,
+ "size=100000,mode=700"))
+ return -1;
+
+ if (mount(NULL, "/tmp", NULL, MS_PRIVATE, 0))
+ return -1;
+
+ if (mkdir(SET_GROUP_FROM, 0777))
+ return -1;
+
+ if (mkdir(SET_GROUP_TO, 0777))
+ return -1;
+
+ if (mount("testing", SET_GROUP_FROM, "tmpfs", MS_NOATIME | MS_NODEV,
+ "size=100000,mode=700"))
+ return -1;
+
+ if (mount(SET_GROUP_FROM, SET_GROUP_TO, NULL, MS_BIND, NULL))
+ return -1;
+
+ if (mount(NULL, SET_GROUP_FROM, NULL, MS_SHARED, 0))
+ return -1;
+
+ ret = syscall(SYS_move_mount, AT_FDCWD, SET_GROUP_FROM,
+ AT_FDCWD, SET_GROUP_TO, MOVE_MOUNT_SET_GROUP);
+ umount2("/tmp", MNT_DETACH);
+
+ return ret < 0 ? false : true;
+}
+
+FIXTURE(move_mount_set_group) {
+};
+
+#define SET_GROUP_A "/tmp/A"
+
+FIXTURE_SETUP(move_mount_set_group)
+{
+ int ret;
+
+ ASSERT_EQ(prepare_unpriv_mountns(), 0);
+
+ ret = move_mount_set_group_supported();
+ ASSERT_GE(ret, 0);
+ if (!ret)
+ SKIP(return, "move_mount(MOVE_MOUNT_SET_GROUP) is not supported");
+
+ umount2("/tmp", MNT_DETACH);
+
+ ASSERT_EQ(mount("testing", "/tmp", "tmpfs", MS_NOATIME | MS_NODEV,
+ "size=100000,mode=700"), 0);
+
+ ASSERT_EQ(mkdir(SET_GROUP_A, 0777), 0);
+
+ ASSERT_EQ(mount("testing", SET_GROUP_A, "tmpfs", MS_NOATIME | MS_NODEV,
+ "size=100000,mode=700"), 0);
+}
+
+FIXTURE_TEARDOWN(move_mount_set_group)
+{
+ int ret;
+
+ ret = move_mount_set_group_supported();
+ ASSERT_GE(ret, 0);
+ if (!ret)
+ SKIP(return, "move_mount(MOVE_MOUNT_SET_GROUP) is not supported");
+
+ umount2("/tmp", MNT_DETACH);
+}
+
+#define __STACK_SIZE (8 * 1024 * 1024)
+static pid_t do_clone(int (*fn)(void *), void *arg, int flags)
+{
+ void *stack;
+
+ stack = malloc(__STACK_SIZE);
+ if (!stack)
+ return -ENOMEM;
+
+#ifdef __ia64__
+ return __clone2(fn, stack, __STACK_SIZE, flags | SIGCHLD, arg, NULL);
+#else
+ return clone(fn, stack + __STACK_SIZE, flags | SIGCHLD, arg, NULL);
+#endif
+}
+
+static int wait_for_pid(pid_t pid)
+{
+ int status, ret;
+
+again:
+ ret = waitpid(pid, &status, 0);
+ if (ret == -1) {
+ if (errno == EINTR)
+ goto again;
+
+ return -1;
+ }
+
+ if (!WIFEXITED(status))
+ return -1;
+
+ return WEXITSTATUS(status);
+}
+
+struct child_args {
+ int unsfd;
+ int mntnsfd;
+ bool shared;
+ int mntfd;
+};
+
+static int get_nestedns_mount_cb(void *data)
+{
+ struct child_args *ca = (struct child_args *)data;
+ int ret;
+
+ ret = prepare_unpriv_mountns();
+ if (ret)
+ return 1;
+
+ if (ca->shared) {
+ ret = mount(NULL, SET_GROUP_A, NULL, MS_SHARED, 0);
+ if (ret)
+ return 1;
+ }
+
+ ret = open("/proc/self/ns/user", O_RDONLY);
+ if (ret < 0)
+ return 1;
+ ca->unsfd = ret;
+
+ ret = open("/proc/self/ns/mnt", O_RDONLY);
+ if (ret < 0)
+ return 1;
+ ca->mntnsfd = ret;
+
+ ret = open(SET_GROUP_A, O_RDONLY);
+ if (ret < 0)
+ return 1;
+ ca->mntfd = ret;
+
+ return 0;
+}
+
+TEST_F(move_mount_set_group, complex_sharing_copying)
+{
+ struct child_args ca_from = {
+ .shared = true,
+ };
+ struct child_args ca_to = {
+ .shared = false,
+ };
+ pid_t pid;
+ int ret;
+
+ ret = move_mount_set_group_supported();
+ ASSERT_GE(ret, 0);
+ if (!ret)
+ SKIP(return, "move_mount(MOVE_MOUNT_SET_GROUP) is not supported");
+
+ pid = do_clone(get_nestedns_mount_cb, (void *)&ca_from, CLONE_VFORK |
+ CLONE_VM | CLONE_FILES); ASSERT_GT(pid, 0);
+ ASSERT_EQ(wait_for_pid(pid), 0);
+
+ pid = do_clone(get_nestedns_mount_cb, (void *)&ca_to, CLONE_VFORK |
+ CLONE_VM | CLONE_FILES); ASSERT_GT(pid, 0);
+ ASSERT_EQ(wait_for_pid(pid), 0);
+
+ ASSERT_EQ(syscall(SYS_move_mount, ca_from.mntfd, "",
+ ca_to.mntfd, "", MOVE_MOUNT_SET_GROUP
+ | MOVE_MOUNT_F_EMPTY_PATH | MOVE_MOUNT_T_EMPTY_PATH),
+ 0);
+
+ ASSERT_EQ(setns(ca_to.mntnsfd, CLONE_NEWNS), 0);
+ ASSERT_EQ(is_shared_mount(SET_GROUP_A), 1);
+}
+
+TEST_HARNESS_MAIN
--
Best regards, Tikhomirov Pavel
Software Developer, Virtuozzo.