// 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"#include "../filesystems/wrappers.h" 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