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// SPDX-License-Identifier: GPL-2.0-or-later
// Copyright (c) 2024 Christian Brauner <brauner@kernel.org>
#define _GNU_SOURCE
#include <fcntl.h>
#include <limits.h>
#include <sched.h>
#include <stdio.h>
#include <string.h>
#include <linux/fs.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/mount.h>
#include <unistd.h>
#include "pidfd.h"
#include "../kselftest_harness.h"
#ifndef __NR_open_tree
#if defined __alpha__
#define __NR_open_tree 538
#elif defined _MIPS_SIM
#if _MIPS_SIM == _MIPS_SIM_ABI32 /* o32 */
#define __NR_open_tree 4428
#endif
#if _MIPS_SIM == _MIPS_SIM_NABI32 /* n32 */
#define __NR_open_tree 6428
#endif
#if _MIPS_SIM == _MIPS_SIM_ABI64 /* n64 */
#define __NR_open_tree 5428
#endif
#elif defined __ia64__
#define __NR_open_tree (428 + 1024)
#else
#define __NR_open_tree 428
#endif
#endif
#ifndef __NR_move_mount
#if defined __alpha__
#define __NR_move_mount 539
#elif defined _MIPS_SIM
#if _MIPS_SIM == _MIPS_SIM_ABI32 /* o32 */
#define __NR_move_mount 4429
#endif
#if _MIPS_SIM == _MIPS_SIM_NABI32 /* n32 */
#define __NR_move_mount 6429
#endif
#if _MIPS_SIM == _MIPS_SIM_ABI64 /* n64 */
#define __NR_move_mount 5429
#endif
#elif defined __ia64__
#define __NR_move_mount (428 + 1024)
#else
#define __NR_move_mount 429
#endif
#endif
#ifndef MOVE_MOUNT_F_EMPTY_PATH
#define MOVE_MOUNT_F_EMPTY_PATH 0x00000004 /* Empty from path permitted */
#endif
#ifndef MOVE_MOUNT_F_EMPTY_PATH
#define MOVE_MOUNT_T_EMPTY_PATH 0x00000040 /* Empty to path permitted */
#endif
static inline int sys_move_mount(int from_dfd, const char *from_pathname,
int to_dfd, const char *to_pathname,
unsigned int flags)
{
return syscall(__NR_move_mount, from_dfd, from_pathname, to_dfd,
to_pathname, flags);
}
#ifndef OPEN_TREE_CLONE
#define OPEN_TREE_CLONE 1
#endif
#ifndef OPEN_TREE_CLOEXEC
#define OPEN_TREE_CLOEXEC O_CLOEXEC
#endif
#ifndef AT_RECURSIVE
#define AT_RECURSIVE 0x8000 /* Apply to the entire subtree */
#endif
static inline int sys_open_tree(int dfd, const char *filename, unsigned int flags)
{
return syscall(__NR_open_tree, dfd, filename, flags);
}
FIXTURE(pidfd_bind_mount) {
char template[PATH_MAX];
int fd_tmp;
int pidfd;
struct stat st1;
struct stat st2;
__u32 gen1;
__u32 gen2;
bool must_unmount;
};
FIXTURE_SETUP(pidfd_bind_mount)
{
self->fd_tmp = -EBADF;
self->must_unmount = false;
ASSERT_EQ(unshare(CLONE_NEWNS), 0);
ASSERT_LE(snprintf(self->template, PATH_MAX, "%s", P_tmpdir "/pidfd_bind_mount_XXXXXX"), PATH_MAX);
self->fd_tmp = mkstemp(self->template);
ASSERT_GE(self->fd_tmp, 0);
self->pidfd = sys_pidfd_open(getpid(), 0);
ASSERT_GE(self->pidfd, 0);
ASSERT_GE(fstat(self->pidfd, &self->st1), 0);
ASSERT_EQ(ioctl(self->pidfd, FS_IOC_GETVERSION, &self->gen1), 0);
}
FIXTURE_TEARDOWN(pidfd_bind_mount)
{
ASSERT_EQ(close(self->fd_tmp), 0);
if (self->must_unmount)
ASSERT_EQ(umount2(self->template, 0), 0);
ASSERT_EQ(unlink(self->template), 0);
}
/*
* Test that a detached mount can be created for a pidfd and then
* attached to the filesystem hierarchy.
*/
TEST_F(pidfd_bind_mount, bind_mount)
{
int fd_tree;
fd_tree = sys_open_tree(self->pidfd, "", OPEN_TREE_CLONE | OPEN_TREE_CLOEXEC | AT_EMPTY_PATH);
ASSERT_GE(fd_tree, 0);
ASSERT_EQ(move_mount(fd_tree, "", self->fd_tmp, "", MOVE_MOUNT_F_EMPTY_PATH | MOVE_MOUNT_T_EMPTY_PATH), 0);
self->must_unmount = true;
ASSERT_EQ(close(fd_tree), 0);
}
/* Test that a pidfd can be reopened through procfs. */
TEST_F(pidfd_bind_mount, reopen)
{
int pidfd;
char proc_path[PATH_MAX];
sprintf(proc_path, "/proc/self/fd/%d", self->pidfd);
pidfd = open(proc_path, O_RDONLY | O_NOCTTY | O_CLOEXEC);
ASSERT_GE(pidfd, 0);
ASSERT_GE(fstat(self->pidfd, &self->st2), 0);
ASSERT_EQ(ioctl(self->pidfd, FS_IOC_GETVERSION, &self->gen2), 0);
ASSERT_TRUE(self->st1.st_dev == self->st2.st_dev && self->st1.st_ino == self->st2.st_ino);
ASSERT_TRUE(self->gen1 == self->gen2);
ASSERT_EQ(close(pidfd), 0);
}
/*
* Test that a detached mount can be created for a pidfd and then
* attached to the filesystem hierarchy and reopened.
*/
TEST_F(pidfd_bind_mount, bind_mount_reopen)
{
int fd_tree, fd_pidfd_mnt;
fd_tree = sys_open_tree(self->pidfd, "", OPEN_TREE_CLONE | OPEN_TREE_CLOEXEC | AT_EMPTY_PATH);
ASSERT_GE(fd_tree, 0);
ASSERT_EQ(move_mount(fd_tree, "", self->fd_tmp, "", MOVE_MOUNT_F_EMPTY_PATH | MOVE_MOUNT_T_EMPTY_PATH), 0);
self->must_unmount = true;
fd_pidfd_mnt = openat(-EBADF, self->template, O_RDONLY | O_NOCTTY | O_CLOEXEC);
ASSERT_GE(fd_pidfd_mnt, 0);
ASSERT_GE(fstat(fd_tree, &self->st2), 0);
ASSERT_EQ(ioctl(fd_pidfd_mnt, FS_IOC_GETVERSION, &self->gen2), 0);
ASSERT_TRUE(self->st1.st_dev == self->st2.st_dev && self->st1.st_ino == self->st2.st_ino);
ASSERT_TRUE(self->gen1 == self->gen2);
ASSERT_EQ(close(fd_tree), 0);
ASSERT_EQ(close(fd_pidfd_mnt), 0);
}
TEST_HARNESS_MAIN
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