1 // SPDX-License-Identifier: GPL-2.0-or-later 2 // Copyright (c) 2024 Christian Brauner <brauner@kernel.org> 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 19 #ifndef __NR_open_tree 20 #if defined __alpha__ 21 #define __NR_open_tree 538 22 #elif defined _MIPS_SIM 23 #if _MIPS_SIM == _MIPS_SIM_ABI32 /* o32 */ 24 #define __NR_open_tree 4428 25 #endif 26 #if _MIPS_SIM == _MIPS_SIM_NABI32 /* n32 */ 27 #define __NR_open_tree 6428 28 #endif 29 #if _MIPS_SIM == _MIPS_SIM_ABI64 /* n64 */ 30 #define __NR_open_tree 5428 31 #endif 32 #elif defined __ia64__ 33 #define __NR_open_tree (428 + 1024) 34 #else 35 #define __NR_open_tree 428 36 #endif 37 #endif 38 39 #ifndef __NR_move_mount 40 #if defined __alpha__ 41 #define __NR_move_mount 539 42 #elif defined _MIPS_SIM 43 #if _MIPS_SIM == _MIPS_SIM_ABI32 /* o32 */ 44 #define __NR_move_mount 4429 45 #endif 46 #if _MIPS_SIM == _MIPS_SIM_NABI32 /* n32 */ 47 #define __NR_move_mount 6429 48 #endif 49 #if _MIPS_SIM == _MIPS_SIM_ABI64 /* n64 */ 50 #define __NR_move_mount 5429 51 #endif 52 #elif defined __ia64__ 53 #define __NR_move_mount (428 + 1024) 54 #else 55 #define __NR_move_mount 429 56 #endif 57 #endif 58 59 #ifndef MOVE_MOUNT_F_EMPTY_PATH 60 #define MOVE_MOUNT_F_EMPTY_PATH 0x00000004 /* Empty from path permitted */ 61 #endif 62 63 #ifndef MOVE_MOUNT_F_EMPTY_PATH 64 #define MOVE_MOUNT_T_EMPTY_PATH 0x00000040 /* Empty to path permitted */ 65 #endif 66 67 static inline int sys_move_mount(int from_dfd, const char *from_pathname, 68 int to_dfd, const char *to_pathname, 69 unsigned int flags) 70 { 71 return syscall(__NR_move_mount, from_dfd, from_pathname, to_dfd, 72 to_pathname, flags); 73 } 74 75 #ifndef OPEN_TREE_CLONE 76 #define OPEN_TREE_CLONE 1 77 #endif 78 79 #ifndef OPEN_TREE_CLOEXEC 80 #define OPEN_TREE_CLOEXEC O_CLOEXEC 81 #endif 82 83 #ifndef AT_RECURSIVE 84 #define AT_RECURSIVE 0x8000 /* Apply to the entire subtree */ 85 #endif 86 87 static inline int sys_open_tree(int dfd, const char *filename, unsigned int flags) 88 { 89 return syscall(__NR_open_tree, dfd, filename, flags); 90 } 91 92 FIXTURE(pidfd_bind_mount) { 93 char template[PATH_MAX]; 94 int fd_tmp; 95 int pidfd; 96 struct stat st1; 97 struct stat st2; 98 __u32 gen1; 99 __u32 gen2; 100 bool must_unmount; 101 }; 102 103 FIXTURE_SETUP(pidfd_bind_mount) 104 { 105 self->fd_tmp = -EBADF; 106 self->must_unmount = false; 107 ASSERT_EQ(unshare(CLONE_NEWNS), 0); 108 ASSERT_LE(snprintf(self->template, PATH_MAX, "%s", P_tmpdir "/pidfd_bind_mount_XXXXXX"), PATH_MAX); 109 self->fd_tmp = mkstemp(self->template); 110 ASSERT_GE(self->fd_tmp, 0); 111 self->pidfd = sys_pidfd_open(getpid(), 0); 112 ASSERT_GE(self->pidfd, 0); 113 ASSERT_GE(fstat(self->pidfd, &self->st1), 0); 114 ASSERT_EQ(ioctl(self->pidfd, FS_IOC_GETVERSION, &self->gen1), 0); 115 } 116 117 FIXTURE_TEARDOWN(pidfd_bind_mount) 118 { 119 ASSERT_EQ(close(self->fd_tmp), 0); 120 if (self->must_unmount) 121 ASSERT_EQ(umount2(self->template, 0), 0); 122 ASSERT_EQ(unlink(self->template), 0); 123 } 124 125 /* 126 * Test that a detached mount can be created for a pidfd and then 127 * attached to the filesystem hierarchy. 128 */ 129 TEST_F(pidfd_bind_mount, bind_mount) 130 { 131 int fd_tree; 132 133 fd_tree = sys_open_tree(self->pidfd, "", OPEN_TREE_CLONE | OPEN_TREE_CLOEXEC | AT_EMPTY_PATH); 134 ASSERT_GE(fd_tree, 0); 135 136 ASSERT_EQ(move_mount(fd_tree, "", self->fd_tmp, "", MOVE_MOUNT_F_EMPTY_PATH | MOVE_MOUNT_T_EMPTY_PATH), 0); 137 self->must_unmount = true; 138 139 ASSERT_EQ(close(fd_tree), 0); 140 } 141 142 /* Test that a pidfd can be reopened through procfs. */ 143 TEST_F(pidfd_bind_mount, reopen) 144 { 145 int pidfd; 146 char proc_path[PATH_MAX]; 147 148 sprintf(proc_path, "/proc/self/fd/%d", self->pidfd); 149 pidfd = open(proc_path, O_RDONLY | O_NOCTTY | O_CLOEXEC); 150 ASSERT_GE(pidfd, 0); 151 152 ASSERT_GE(fstat(self->pidfd, &self->st2), 0); 153 ASSERT_EQ(ioctl(self->pidfd, FS_IOC_GETVERSION, &self->gen2), 0); 154 155 ASSERT_TRUE(self->st1.st_dev == self->st2.st_dev && self->st1.st_ino == self->st2.st_ino); 156 ASSERT_TRUE(self->gen1 == self->gen2); 157 158 ASSERT_EQ(close(pidfd), 0); 159 } 160 161 /* 162 * Test that a detached mount can be created for a pidfd and then 163 * attached to the filesystem hierarchy and reopened. 164 */ 165 TEST_F(pidfd_bind_mount, bind_mount_reopen) 166 { 167 int fd_tree, fd_pidfd_mnt; 168 169 fd_tree = sys_open_tree(self->pidfd, "", OPEN_TREE_CLONE | OPEN_TREE_CLOEXEC | AT_EMPTY_PATH); 170 ASSERT_GE(fd_tree, 0); 171 172 ASSERT_EQ(move_mount(fd_tree, "", self->fd_tmp, "", MOVE_MOUNT_F_EMPTY_PATH | MOVE_MOUNT_T_EMPTY_PATH), 0); 173 self->must_unmount = true; 174 175 fd_pidfd_mnt = openat(-EBADF, self->template, O_RDONLY | O_NOCTTY | O_CLOEXEC); 176 ASSERT_GE(fd_pidfd_mnt, 0); 177 178 ASSERT_GE(fstat(fd_tree, &self->st2), 0); 179 ASSERT_EQ(ioctl(fd_pidfd_mnt, FS_IOC_GETVERSION, &self->gen2), 0); 180 181 ASSERT_TRUE(self->st1.st_dev == self->st2.st_dev && self->st1.st_ino == self->st2.st_ino); 182 ASSERT_TRUE(self->gen1 == self->gen2); 183 184 ASSERT_EQ(close(fd_tree), 0); 185 ASSERT_EQ(close(fd_pidfd_mnt), 0); 186 } 187 188 TEST_HARNESS_MAIN 189