diff options
Diffstat (limited to 'tools/testing/selftests/move_mount_set_group/move_mount_set_group_test.c')
| -rw-r--r-- | tools/testing/selftests/move_mount_set_group/move_mount_set_group_test.c | 375 |
1 files changed, 375 insertions, 0 deletions
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..50ed5d475dd1 --- /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 bool 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; +} + +FIXTURE(move_mount_set_group) { +}; + +#define SET_GROUP_A "/tmp/A" + +FIXTURE_SETUP(move_mount_set_group) +{ + bool 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) +{ + bool 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; + bool 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 |