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1// SPDX-License-Identifier: GPL-2.0-or-later
2// Copyright (c) 2024 Christian Brauner <[email protected]>
3
4#define _GNU_SOURCE
5#include <fcntl.h>
6#include <limits.h>
7#include <sched.h>
8#include <stdio.h>
9#include <string.h>
10#include <linux/fs.h>
11#include <sys/ioctl.h>
12#include <sys/stat.h>
13#include <sys/mount.h>
14#include <unistd.h>
15
16#include "pidfd.h"
17#include "kselftest_harness.h"
18#include "../filesystems/wrappers.h"
19
20FIXTURE(pidfd_bind_mount) {
21 char template[PATH_MAX];
22 int fd_tmp;
23 int pidfd;
24 struct stat st1;
25 struct stat st2;
26 __u32 gen1;
27 __u32 gen2;
28 bool must_unmount;
29};
30
31FIXTURE_SETUP(pidfd_bind_mount)
32{
33 self->fd_tmp = -EBADF;
34 self->must_unmount = false;
35 ASSERT_EQ(unshare(CLONE_NEWNS), 0);
36 ASSERT_LE(snprintf(self->template, PATH_MAX, "%s", P_tmpdir "/pidfd_bind_mount_XXXXXX"), PATH_MAX);
37 self->fd_tmp = mkstemp(self->template);
38 ASSERT_GE(self->fd_tmp, 0);
39 self->pidfd = sys_pidfd_open(getpid(), 0);
40 ASSERT_GE(self->pidfd, 0);
41 ASSERT_GE(fstat(self->pidfd, &self->st1), 0);
42 ASSERT_EQ(ioctl(self->pidfd, FS_IOC_GETVERSION, &self->gen1), 0);
43}
44
45FIXTURE_TEARDOWN(pidfd_bind_mount)
46{
47 ASSERT_EQ(close(self->fd_tmp), 0);
48 if (self->must_unmount)
49 ASSERT_EQ(umount2(self->template, 0), 0);
50 ASSERT_EQ(unlink(self->template), 0);
51}
52
53/*
54 * Test that a detached mount can be created for a pidfd and then
55 * attached to the filesystem hierarchy.
56 */
57TEST_F(pidfd_bind_mount, bind_mount)
58{
59 int fd_tree;
60
61 fd_tree = sys_open_tree(self->pidfd, "", OPEN_TREE_CLONE | OPEN_TREE_CLOEXEC | AT_EMPTY_PATH);
62 ASSERT_GE(fd_tree, 0);
63
64 ASSERT_EQ(move_mount(fd_tree, "", self->fd_tmp, "", MOVE_MOUNT_F_EMPTY_PATH | MOVE_MOUNT_T_EMPTY_PATH), 0);
65 self->must_unmount = true;
66
67 ASSERT_EQ(close(fd_tree), 0);
68}
69
70/* Test that a pidfd can be reopened through procfs. */
71TEST_F(pidfd_bind_mount, reopen)
72{
73 int pidfd;
74 char proc_path[PATH_MAX];
75
76 sprintf(proc_path, "/proc/self/fd/%d", self->pidfd);
77 pidfd = open(proc_path, O_RDONLY | O_NOCTTY | O_CLOEXEC);
78 ASSERT_GE(pidfd, 0);
79
80 ASSERT_GE(fstat(self->pidfd, &self->st2), 0);
81 ASSERT_EQ(ioctl(self->pidfd, FS_IOC_GETVERSION, &self->gen2), 0);
82
83 ASSERT_TRUE(self->st1.st_dev == self->st2.st_dev && self->st1.st_ino == self->st2.st_ino);
84 ASSERT_TRUE(self->gen1 == self->gen2);
85
86 ASSERT_EQ(close(pidfd), 0);
87}
88
89/*
90 * Test that a detached mount can be created for a pidfd and then
91 * attached to the filesystem hierarchy and reopened.
92 */
93TEST_F(pidfd_bind_mount, bind_mount_reopen)
94{
95 int fd_tree, fd_pidfd_mnt;
96
97 fd_tree = sys_open_tree(self->pidfd, "", OPEN_TREE_CLONE | OPEN_TREE_CLOEXEC | AT_EMPTY_PATH);
98 ASSERT_GE(fd_tree, 0);
99
100 ASSERT_EQ(move_mount(fd_tree, "", self->fd_tmp, "", MOVE_MOUNT_F_EMPTY_PATH | MOVE_MOUNT_T_EMPTY_PATH), 0);
101 self->must_unmount = true;
102
103 fd_pidfd_mnt = openat(-EBADF, self->template, O_RDONLY | O_NOCTTY | O_CLOEXEC);
104 ASSERT_GE(fd_pidfd_mnt, 0);
105
106 ASSERT_GE(fstat(fd_tree, &self->st2), 0);
107 ASSERT_EQ(ioctl(fd_pidfd_mnt, FS_IOC_GETVERSION, &self->gen2), 0);
108
109 ASSERT_TRUE(self->st1.st_dev == self->st2.st_dev && self->st1.st_ino == self->st2.st_ino);
110 ASSERT_TRUE(self->gen1 == self->gen2);
111
112 ASSERT_EQ(close(fd_tree), 0);
113 ASSERT_EQ(close(fd_pidfd_mnt), 0);
114}
115
116TEST_HARNESS_MAIN