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 <errno.h> 6 #include <limits.h> 7 #include <linux/types.h> 8 #include <stdio.h> 9 #include <sys/ioctl.h> 10 #include <sys/syscall.h> 11 12 #include "../../tools/testing/selftests/pidfd/pidfd.h" 13 14 #define die_errno(format, ...) \ 15 do { \ 16 fprintf(stderr, "%m | %s: %d: %s: " format "\n", __FILE__, \ 17 __LINE__, __func__, ##__VA_ARGS__); \ 18 exit(EXIT_FAILURE); \ 19 } while (0) 20 21 /* Get the id for a mount namespace */ 22 #define NS_GET_MNTNS_ID _IO(0xb7, 0x5) 23 /* Get next mount namespace. */ 24 25 struct mnt_ns_info { 26 __u32 size; 27 __u32 nr_mounts; 28 __u64 mnt_ns_id; 29 }; 30 31 #define MNT_NS_INFO_SIZE_VER0 16 /* size of first published struct */ 32 33 /* Get information about namespace. */ 34 #define NS_MNT_GET_INFO _IOR(0xb7, 10, struct mnt_ns_info) 35 /* Get next namespace. */ 36 #define NS_MNT_GET_NEXT _IOR(0xb7, 11, struct mnt_ns_info) 37 /* Get previous namespace. */ 38 #define NS_MNT_GET_PREV _IOR(0xb7, 12, struct mnt_ns_info) 39 40 #define PIDFD_GET_MNT_NAMESPACE _IO(0xFF, 3) 41 42 #ifndef __NR_listmount 43 #define __NR_listmount 458 44 #endif 45 46 #ifndef __NR_statmount 47 #define __NR_statmount 457 48 #endif 49 50 /* @mask bits for statmount(2) */ 51 #define STATMOUNT_SB_BASIC 0x00000001U /* Want/got sb_... */ 52 #define STATMOUNT_MNT_BASIC 0x00000002U /* Want/got mnt_... */ 53 #define STATMOUNT_PROPAGATE_FROM 0x00000004U /* Want/got propagate_from */ 54 #define STATMOUNT_MNT_ROOT 0x00000008U /* Want/got mnt_root */ 55 #define STATMOUNT_MNT_POINT 0x00000010U /* Want/got mnt_point */ 56 #define STATMOUNT_FS_TYPE 0x00000020U /* Want/got fs_type */ 57 #define STATMOUNT_MNT_NS_ID 0x00000040U /* Want/got mnt_ns_id */ 58 #define STATMOUNT_MNT_OPTS 0x00000080U /* Want/got mnt_opts */ 59 60 #define STATX_MNT_ID_UNIQUE 0x00004000U /* Want/got extended stx_mount_id */ 61 62 struct statmount { 63 __u32 size; 64 __u32 mnt_opts; 65 __u64 mask; 66 __u32 sb_dev_major; 67 __u32 sb_dev_minor; 68 __u64 sb_magic; 69 __u32 sb_flags; 70 __u32 fs_type; 71 __u64 mnt_id; 72 __u64 mnt_parent_id; 73 __u32 mnt_id_old; 74 __u32 mnt_parent_id_old; 75 __u64 mnt_attr; 76 __u64 mnt_propagation; 77 __u64 mnt_peer_group; 78 __u64 mnt_master; 79 __u64 propagate_from; 80 __u32 mnt_root; 81 __u32 mnt_point; 82 __u64 mnt_ns_id; 83 __u64 __spare2[49]; 84 char str[]; 85 }; 86 87 struct mnt_id_req { 88 __u32 size; 89 __u32 spare; 90 __u64 mnt_id; 91 __u64 param; 92 __u64 mnt_ns_id; 93 }; 94 95 #define MNT_ID_REQ_SIZE_VER1 32 /* sizeof second published struct */ 96 97 #define LSMT_ROOT 0xffffffffffffffff /* root mount */ 98 99 static int __statmount(__u64 mnt_id, __u64 mnt_ns_id, __u64 mask, 100 struct statmount *stmnt, size_t bufsize, 101 unsigned int flags) 102 { 103 struct mnt_id_req req = { 104 .size = MNT_ID_REQ_SIZE_VER1, 105 .mnt_id = mnt_id, 106 .param = mask, 107 .mnt_ns_id = mnt_ns_id, 108 }; 109 110 return syscall(__NR_statmount, &req, stmnt, bufsize, flags); 111 } 112 113 static struct statmount *sys_statmount(__u64 mnt_id, __u64 mnt_ns_id, 114 __u64 mask, unsigned int flags) 115 { 116 size_t bufsize = 1 << 15; 117 struct statmount *stmnt = NULL, *tmp = NULL; 118 int ret; 119 120 for (;;) { 121 tmp = realloc(stmnt, bufsize); 122 if (!tmp) 123 goto out; 124 125 stmnt = tmp; 126 ret = __statmount(mnt_id, mnt_ns_id, mask, stmnt, bufsize, flags); 127 if (!ret) 128 return stmnt; 129 130 if (errno != EOVERFLOW) 131 goto out; 132 133 bufsize <<= 1; 134 if (bufsize >= UINT_MAX / 2) 135 goto out; 136 } 137 138 out: 139 free(stmnt); 140 return NULL; 141 } 142 143 static ssize_t sys_listmount(__u64 mnt_id, __u64 last_mnt_id, __u64 mnt_ns_id, 144 __u64 list[], size_t num, unsigned int flags) 145 { 146 struct mnt_id_req req = { 147 .size = MNT_ID_REQ_SIZE_VER1, 148 .mnt_id = mnt_id, 149 .param = last_mnt_id, 150 .mnt_ns_id = mnt_ns_id, 151 }; 152 153 return syscall(__NR_listmount, &req, list, num, flags); 154 } 155 156 int main(int argc, char *argv[]) 157 { 158 #define LISTMNT_BUFFER 10 159 __u64 list[LISTMNT_BUFFER], last_mnt_id = 0; 160 int ret, pidfd, fd_mntns; 161 struct mnt_ns_info info = {}; 162 163 pidfd = sys_pidfd_open(getpid(), 0); 164 if (pidfd < 0) 165 die_errno("pidfd_open failed"); 166 167 fd_mntns = ioctl(pidfd, PIDFD_GET_MNT_NAMESPACE, 0); 168 if (fd_mntns < 0) 169 die_errno("ioctl(PIDFD_GET_MNT_NAMESPACE) failed"); 170 171 ret = ioctl(fd_mntns, NS_MNT_GET_INFO, &info); 172 if (ret < 0) 173 die_errno("ioctl(NS_GET_MNTNS_ID) failed"); 174 175 printf("Listing %u mounts for mount namespace %llu\n", 176 info.nr_mounts, info.mnt_ns_id); 177 for (;;) { 178 ssize_t nr_mounts; 179 next: 180 nr_mounts = sys_listmount(LSMT_ROOT, last_mnt_id, 181 info.mnt_ns_id, list, LISTMNT_BUFFER, 182 0); 183 if (nr_mounts <= 0) { 184 int fd_mntns_next; 185 186 printf("Finished listing %u mounts for mount namespace %llu\n\n", 187 info.nr_mounts, info.mnt_ns_id); 188 fd_mntns_next = ioctl(fd_mntns, NS_MNT_GET_NEXT, &info); 189 if (fd_mntns_next < 0) { 190 if (errno == ENOENT) { 191 printf("Finished listing all mount namespaces\n"); 192 exit(0); 193 } 194 die_errno("ioctl(NS_MNT_GET_NEXT) failed"); 195 } 196 close(fd_mntns); 197 fd_mntns = fd_mntns_next; 198 last_mnt_id = 0; 199 printf("Listing %u mounts for mount namespace %llu\n", 200 info.nr_mounts, info.mnt_ns_id); 201 goto next; 202 } 203 204 for (size_t cur = 0; cur < nr_mounts; cur++) { 205 struct statmount *stmnt; 206 207 last_mnt_id = list[cur]; 208 209 stmnt = sys_statmount(last_mnt_id, info.mnt_ns_id, 210 STATMOUNT_SB_BASIC | 211 STATMOUNT_MNT_BASIC | 212 STATMOUNT_MNT_ROOT | 213 STATMOUNT_MNT_POINT | 214 STATMOUNT_MNT_NS_ID | 215 STATMOUNT_MNT_OPTS | 216 STATMOUNT_FS_TYPE, 0); 217 if (!stmnt) { 218 printf("Failed to statmount(%llu) in mount namespace(%llu)\n", 219 last_mnt_id, info.mnt_ns_id); 220 continue; 221 } 222 223 printf("mnt_id:\t\t%llu\nmnt_parent_id:\t%llu\nfs_type:\t%s\nmnt_root:\t%s\nmnt_point:\t%s\nmnt_opts:\t%s\n\n", 224 stmnt->mnt_id, 225 stmnt->mnt_parent_id, 226 stmnt->str + stmnt->fs_type, 227 stmnt->str + stmnt->mnt_root, 228 stmnt->str + stmnt->mnt_point, 229 stmnt->str + stmnt->mnt_opts); 230 free(stmnt); 231 } 232 } 233 234 exit(0); 235 } 236