tests: add move_mount(MOVE_MOUNT_SET_GROUP) selftest
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 Link: https://lore.kernel.org/r/20210715100714.120228-2-ptikhomirov@virtuozzo.com Cc: Shuah Khan <shuah@kernel.org> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Christian Brauner <christian.brauner@ubuntu.com> Cc: Mattias Nissler <mnissler@chromium.org> Cc: Aleksa Sarai <cyphar@cyphar.com> Cc: Andrei Vagin <avagin@gmail.com> Cc: linux-fsdevel@vger.kernel.org Cc: linux-kselftest@vger.kernel.org Cc: lkml <linux-kernel@vger.kernel.org> Signed-off-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
This commit is contained in:
Pavel Tikhomirov
Christian Brauner
parent
9ffb14ef61
commit
8374f43123
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@ -35,6 +35,7 @@ TARGETS += memory-hotplug
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TARGETS += mincore
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TARGETS += mount
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TARGETS += mount_setattr
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TARGETS += move_mount_set_group
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TARGETS += mqueue
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TARGETS += nci
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TARGETS += net
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@ -0,0 +1 @@
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move_mount_set_group_test
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@ -0,0 +1,7 @@
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# SPDX-License-Identifier: GPL-2.0
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# Makefile for mount selftests.
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CFLAGS = -g -I../../../../usr/include/ -Wall -O2
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TEST_GEN_FILES += move_mount_set_group_test
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include ../lib.mk
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@ -0,0 +1 @@
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CONFIG_USER_NS=y
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@ -0,0 +1,375 @@
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// SPDX-License-Identifier: GPL-2.0
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#define _GNU_SOURCE
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#include <sched.h>
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#include <stdio.h>
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#include <errno.h>
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#include <string.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <sys/mount.h>
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#include <sys/wait.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <stdbool.h>
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#include <stdarg.h>
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#include <sys/syscall.h>
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#include "../kselftest_harness.h"
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#ifndef CLONE_NEWNS
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#define CLONE_NEWNS 0x00020000
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#endif
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#ifndef CLONE_NEWUSER
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#define CLONE_NEWUSER 0x10000000
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#endif
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#ifndef MS_SHARED
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#define MS_SHARED (1 << 20)
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#endif
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#ifndef MS_PRIVATE
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#define MS_PRIVATE (1<<18)
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#endif
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#ifndef MOVE_MOUNT_SET_GROUP
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#define MOVE_MOUNT_SET_GROUP 0x00000100
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#endif
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#ifndef MOVE_MOUNT_F_EMPTY_PATH
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#define MOVE_MOUNT_F_EMPTY_PATH 0x00000004
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#endif
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#ifndef MOVE_MOUNT_T_EMPTY_PATH
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#define MOVE_MOUNT_T_EMPTY_PATH 0x00000040
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#endif
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static ssize_t write_nointr(int fd, const void *buf, size_t count)
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{
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ssize_t ret;
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do {
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ret = write(fd, buf, count);
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} while (ret < 0 && errno == EINTR);
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return ret;
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}
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static int write_file(const char *path, const void *buf, size_t count)
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{
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int fd;
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ssize_t ret;
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fd = open(path, O_WRONLY | O_CLOEXEC | O_NOCTTY | O_NOFOLLOW);
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if (fd < 0)
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return -1;
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ret = write_nointr(fd, buf, count);
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close(fd);
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if (ret < 0 || (size_t)ret != count)
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return -1;
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return 0;
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}
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static int create_and_enter_userns(void)
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{
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uid_t uid;
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gid_t gid;
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char map[100];
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uid = getuid();
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gid = getgid();
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if (unshare(CLONE_NEWUSER))
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return -1;
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if (write_file("/proc/self/setgroups", "deny", sizeof("deny") - 1) &&
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errno != ENOENT)
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return -1;
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snprintf(map, sizeof(map), "0 %d 1", uid);
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if (write_file("/proc/self/uid_map", map, strlen(map)))
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return -1;
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snprintf(map, sizeof(map), "0 %d 1", gid);
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if (write_file("/proc/self/gid_map", map, strlen(map)))
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return -1;
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if (setgid(0))
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return -1;
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if (setuid(0))
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return -1;
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return 0;
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}
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static int prepare_unpriv_mountns(void)
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{
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if (create_and_enter_userns())
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return -1;
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if (unshare(CLONE_NEWNS))
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return -1;
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if (mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, 0))
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return -1;
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return 0;
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}
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static char *get_field(char *src, int nfields)
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{
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int i;
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char *p = src;
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for (i = 0; i < nfields; i++) {
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while (*p && *p != ' ' && *p != '\t')
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p++;
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if (!*p)
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break;
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p++;
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}
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return p;
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}
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static void null_endofword(char *word)
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{
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while (*word && *word != ' ' && *word != '\t')
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word++;
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*word = '\0';
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}
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static bool is_shared_mount(const char *path)
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{
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size_t len = 0;
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char *line = NULL;
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FILE *f = NULL;
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f = fopen("/proc/self/mountinfo", "re");
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if (!f)
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return false;
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while (getline(&line, &len, f) != -1) {
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char *opts, *target;
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target = get_field(line, 4);
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if (!target)
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continue;
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opts = get_field(target, 2);
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if (!opts)
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continue;
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null_endofword(target);
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if (strcmp(target, path) != 0)
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continue;
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null_endofword(opts);
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if (strstr(opts, "shared:"))
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return true;
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}
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free(line);
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fclose(f);
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return false;
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}
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/* Attempt to de-conflict with the selftests tree. */
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#ifndef SKIP
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#define SKIP(s, ...) XFAIL(s, ##__VA_ARGS__)
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#endif
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#define SET_GROUP_FROM "/tmp/move_mount_set_group_supported_from"
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#define SET_GROUP_TO "/tmp/move_mount_set_group_supported_to"
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static int move_mount_set_group_supported(void)
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{
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int ret;
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if (mount("testing", "/tmp", "tmpfs", MS_NOATIME | MS_NODEV,
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"size=100000,mode=700"))
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return -1;
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if (mount(NULL, "/tmp", NULL, MS_PRIVATE, 0))
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return -1;
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if (mkdir(SET_GROUP_FROM, 0777))
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return -1;
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if (mkdir(SET_GROUP_TO, 0777))
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return -1;
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if (mount("testing", SET_GROUP_FROM, "tmpfs", MS_NOATIME | MS_NODEV,
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"size=100000,mode=700"))
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return -1;
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if (mount(SET_GROUP_FROM, SET_GROUP_TO, NULL, MS_BIND, NULL))
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return -1;
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if (mount(NULL, SET_GROUP_FROM, NULL, MS_SHARED, 0))
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return -1;
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ret = syscall(SYS_move_mount, AT_FDCWD, SET_GROUP_FROM,
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AT_FDCWD, SET_GROUP_TO, MOVE_MOUNT_SET_GROUP);
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umount2("/tmp", MNT_DETACH);
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return ret < 0 ? false : true;
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}
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FIXTURE(move_mount_set_group) {
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};
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#define SET_GROUP_A "/tmp/A"
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FIXTURE_SETUP(move_mount_set_group)
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{
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int ret;
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ASSERT_EQ(prepare_unpriv_mountns(), 0);
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ret = move_mount_set_group_supported();
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ASSERT_GE(ret, 0);
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if (!ret)
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SKIP(return, "move_mount(MOVE_MOUNT_SET_GROUP) is not supported");
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umount2("/tmp", MNT_DETACH);
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ASSERT_EQ(mount("testing", "/tmp", "tmpfs", MS_NOATIME | MS_NODEV,
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"size=100000,mode=700"), 0);
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ASSERT_EQ(mkdir(SET_GROUP_A, 0777), 0);
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ASSERT_EQ(mount("testing", SET_GROUP_A, "tmpfs", MS_NOATIME | MS_NODEV,
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"size=100000,mode=700"), 0);
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}
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FIXTURE_TEARDOWN(move_mount_set_group)
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{
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int ret;
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ret = move_mount_set_group_supported();
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ASSERT_GE(ret, 0);
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if (!ret)
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SKIP(return, "move_mount(MOVE_MOUNT_SET_GROUP) is not supported");
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umount2("/tmp", MNT_DETACH);
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}
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#define __STACK_SIZE (8 * 1024 * 1024)
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static pid_t do_clone(int (*fn)(void *), void *arg, int flags)
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{
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void *stack;
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stack = malloc(__STACK_SIZE);
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if (!stack)
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return -ENOMEM;
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#ifdef __ia64__
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return __clone2(fn, stack, __STACK_SIZE, flags | SIGCHLD, arg, NULL);
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#else
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return clone(fn, stack + __STACK_SIZE, flags | SIGCHLD, arg, NULL);
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#endif
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}
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static int wait_for_pid(pid_t pid)
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{
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int status, ret;
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again:
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ret = waitpid(pid, &status, 0);
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if (ret == -1) {
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if (errno == EINTR)
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goto again;
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return -1;
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}
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if (!WIFEXITED(status))
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return -1;
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return WEXITSTATUS(status);
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}
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struct child_args {
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int unsfd;
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int mntnsfd;
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bool shared;
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int mntfd;
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};
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static int get_nestedns_mount_cb(void *data)
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{
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struct child_args *ca = (struct child_args *)data;
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int ret;
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ret = prepare_unpriv_mountns();
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if (ret)
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return 1;
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if (ca->shared) {
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ret = mount(NULL, SET_GROUP_A, NULL, MS_SHARED, 0);
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if (ret)
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return 1;
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}
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ret = open("/proc/self/ns/user", O_RDONLY);
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if (ret < 0)
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return 1;
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ca->unsfd = ret;
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ret = open("/proc/self/ns/mnt", O_RDONLY);
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if (ret < 0)
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return 1;
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ca->mntnsfd = ret;
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ret = open(SET_GROUP_A, O_RDONLY);
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if (ret < 0)
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return 1;
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ca->mntfd = ret;
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return 0;
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}
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TEST_F(move_mount_set_group, complex_sharing_copying)
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{
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struct child_args ca_from = {
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.shared = true,
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};
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struct child_args ca_to = {
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.shared = false,
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};
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pid_t pid;
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int ret;
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ret = move_mount_set_group_supported();
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ASSERT_GE(ret, 0);
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if (!ret)
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SKIP(return, "move_mount(MOVE_MOUNT_SET_GROUP) is not supported");
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pid = do_clone(get_nestedns_mount_cb, (void *)&ca_from, CLONE_VFORK |
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CLONE_VM | CLONE_FILES); ASSERT_GT(pid, 0);
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ASSERT_EQ(wait_for_pid(pid), 0);
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pid = do_clone(get_nestedns_mount_cb, (void *)&ca_to, CLONE_VFORK |
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CLONE_VM | CLONE_FILES); ASSERT_GT(pid, 0);
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ASSERT_EQ(wait_for_pid(pid), 0);
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ASSERT_EQ(syscall(SYS_move_mount, ca_from.mntfd, "",
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ca_to.mntfd, "", MOVE_MOUNT_SET_GROUP
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| MOVE_MOUNT_F_EMPTY_PATH | MOVE_MOUNT_T_EMPTY_PATH),
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0);
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ASSERT_EQ(setns(ca_to.mntnsfd, CLONE_NEWNS), 0);
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ASSERT_EQ(is_shared_mount(SET_GROUP_A), 1);
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}
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TEST_HARNESS_MAIN
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