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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2014 Red Hat, Inc.
* Copyright (C) 2021 SUSE LLC Andrea Cervesato <andrea.cervesato@suse.com>
*/
/*\
* [Description]
*
* Tests a shared mount: shared mount can be replicated to as many
* mountpoints and all the replicas continue to be exactly same.
*
* [Algorithm]
*
* - Creates directories DIR_A, DIR_B and files DIR_A/"A", DIR_B/"B"
* - Unshares mount namespace and makes it private (so mounts/umounts have no
* effect on a real system)
* - Bind mounts directory DIR_A to DIR_A
* - Makes directory DIR_A shared
* - Clones a new child process with CLONE_NEWNS flag
* - There are two test cases (where X is parent namespace and Y child namespace):
* 1. First test case
* .. X: bind mounts DIR_B to DIR_A
* .. Y: must see DIR_A/"B"
* .. X: umounts DIR_A
* 2. Second test case
* .. Y: bind mounts DIR_B to DIR_A
* .. X: must see DIR_A/"B"
* .. Y: umounts DIR_A
*/
#include <sys/wait.h>
#include <sys/mount.h>
#include "mountns.h"
#include "tst_test.h"
#include "lapi/sched.h"
static void child_func(void)
{
TST_CHECKPOINT_WAIT(0);
if (access(DIRA "/B", F_OK) == 0)
tst_res(TPASS, "shared mount in parent passed");
else
tst_res(TFAIL, "shared mount in parent failed");
TST_CHECKPOINT_WAKE_AND_WAIT(0);
/* bind mounts DIRB to DIRA making contents of DIRB visible in DIRA */
SAFE_MOUNT(DIRB, DIRA, "none", MS_BIND, NULL);
TST_CHECKPOINT_WAKE_AND_WAIT(0);
SAFE_UMOUNT(DIRA);
}
static void run(void)
{
const struct tst_clone_args args = {
.flags = CLONE_NEWNS,
.exit_signal = SIGCHLD,
};
SAFE_UNSHARE(CLONE_NEWNS);
/* makes sure parent mounts/umounts have no effect on a real system */
SAFE_MOUNT("none", "/", "none", MS_REC | MS_PRIVATE, NULL);
SAFE_MOUNT(DIRA, DIRA, "none", MS_BIND, NULL);
SAFE_MOUNT("none", DIRA, "none", MS_SHARED, NULL);
if (!SAFE_CLONE(&args)) {
child_func();
return;
}
SAFE_MOUNT(DIRB, DIRA, "none", MS_BIND, NULL);
TST_CHECKPOINT_WAKE_AND_WAIT(0);
SAFE_UMOUNT(DIRA);
TST_CHECKPOINT_WAKE_AND_WAIT(0);
if (access(DIRA "/B", F_OK) == 0)
tst_res(TPASS, "shared mount in child passed");
else
tst_res(TFAIL, "shared mount in child failed");
TST_CHECKPOINT_WAKE(0);
SAFE_WAIT(NULL);
SAFE_UMOUNT(DIRA);
}
static void setup(void)
{
create_folders();
}
static void cleanup(void)
{
umount_folders();
}
static struct tst_test test = {
.setup = setup,
.cleanup = cleanup,
.test_all = run,
.needs_root = 1,
.forks_child = 1,
.needs_checkpoints = 1,
.needs_kconfigs = (const char *[]) {
"CONFIG_USER_NS",
NULL,
},
};
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