samples/vfs/test-list-all-mounts.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 // Copyright (c) 2024 Christian Brauner <[email protected]>
   3
   4 #define _GNU_SOURCE
   5 #include <errno.h>
   6 #include <limits.h>
   7 #include <linux/types.h>
   8 #include <inttypes.h>
   9 #include <stdio.h>
  10
  11 #include "../../tools/testing/selftests/pidfd/pidfd.h"
  12 #include "samples-vfs.h"
  13
  14 static int __statmount(__u64 mnt_id, __u64 mnt_ns_id, __u64 mask,
  15                        struct statmount *stmnt, size_t bufsize,
  16                        unsigned int flags)
  17 {
  18         struct mnt_id_req req = {
  19                 .size           = MNT_ID_REQ_SIZE_VER1,
  20                 .mnt_id         = mnt_id,
  21                 .param          = mask,
  22                 .mnt_ns_id      = mnt_ns_id,
  23         };
  24
  25         return syscall(__NR_statmount, &req, stmnt, bufsize, flags);
  26 }
  27
  28 static struct statmount *sys_statmount(__u64 mnt_id, __u64 mnt_ns_id,
  29                                        __u64 mask, unsigned int flags)
  30 {
  31         size_t bufsize = 1 << 15;
  32         struct statmount *stmnt = NULL, *tmp = NULL;
  33         int ret;
  34
  35         for (;;) {
  36                 tmp = realloc(stmnt, bufsize);
  37                 if (!tmp)
  38                         goto out;
  39
  40                 stmnt = tmp;
  41                 ret = __statmount(mnt_id, mnt_ns_id, mask, stmnt, bufsize, flags);
  42                 if (!ret)
  43                         return stmnt;
  44
  45                 if (errno != EOVERFLOW)
  46                         goto out;
  47
  48                 bufsize <<= 1;
  49                 if (bufsize >= UINT_MAX / 2)
  50                         goto out;
  51         }
  52
  53 out:
  54         free(stmnt);
  55         return NULL;
  56 }
  57
  58 static ssize_t sys_listmount(__u64 mnt_id, __u64 last_mnt_id, __u64 mnt_ns_id,
  59                              __u64 list[], size_t num, unsigned int flags)
  60 {
  61         struct mnt_id_req req = {
  62                 .size           = MNT_ID_REQ_SIZE_VER1,
  63                 .mnt_id         = mnt_id,
  64                 .param          = last_mnt_id,
  65                 .mnt_ns_id      = mnt_ns_id,
  66         };
  67
  68         return syscall(__NR_listmount, &req, list, num, flags);
  69 }
  70
  71 int main(int argc, char *argv[])
  72 {
  73 #define LISTMNT_BUFFER 10
  74         __u64 list[LISTMNT_BUFFER], last_mnt_id = 0;
  75         int ret, pidfd, fd_mntns;
  76         struct mnt_ns_info info = {};
  77
  78         pidfd = sys_pidfd_open(getpid(), 0);
  79         if (pidfd < 0)
  80                 die_errno("pidfd_open failed");
  81
  82         fd_mntns = ioctl(pidfd, PIDFD_GET_MNT_NAMESPACE, 0);
  83         if (fd_mntns < 0)
  84                 die_errno("ioctl(PIDFD_GET_MNT_NAMESPACE) failed");
  85
  86         ret = ioctl(fd_mntns, NS_MNT_GET_INFO, &info);
  87         if (ret < 0)
  88                 die_errno("ioctl(NS_GET_MNTNS_ID) failed");
  89
  90         printf("Listing %u mounts for mount namespace %" PRIu64 "\n",
  91                info.nr_mounts, (uint64_t)info.mnt_ns_id);
  92         for (;;) {
  93                 ssize_t nr_mounts;
  94 next:
  95                 nr_mounts = sys_listmount(LSMT_ROOT, last_mnt_id,
  96                                           info.mnt_ns_id, list, LISTMNT_BUFFER,
  97                                           0);
  98                 if (nr_mounts <= 0) {
  99                         int fd_mntns_next;
 100
 101                         printf("Finished listing %u mounts for mount namespace %" PRIu64 "\n\n",
 102                                info.nr_mounts, (uint64_t)info.mnt_ns_id);
 103                         fd_mntns_next = ioctl(fd_mntns, NS_MNT_GET_NEXT, &info);
 104                         if (fd_mntns_next < 0) {
 105                                 if (errno == ENOENT) {
 106                                         printf("Finished listing all mount namespaces\n");
 107                                         exit(0);
 108                                 }
 109                                 die_errno("ioctl(NS_MNT_GET_NEXT) failed");
 110                         }
 111                         close(fd_mntns);
 112                         fd_mntns = fd_mntns_next;
 113                         last_mnt_id = 0;
 114                         printf("Listing %u mounts for mount namespace %" PRIu64 "\n",
 115                                info.nr_mounts, (uint64_t)info.mnt_ns_id);
 116                         goto next;
 117                 }
 118
 119                 for (size_t cur = 0; cur < nr_mounts; cur++) {
 120                         struct statmount *stmnt;
 121
 122                         last_mnt_id = list[cur];
 123
 124                         stmnt = sys_statmount(last_mnt_id, info.mnt_ns_id,
 125                                               STATMOUNT_SB_BASIC |
 126                                               STATMOUNT_MNT_BASIC |
 127                                               STATMOUNT_MNT_ROOT |
 128                                               STATMOUNT_MNT_POINT |
 129                                               STATMOUNT_MNT_NS_ID |
 130                                               STATMOUNT_MNT_OPTS |
 131                                               STATMOUNT_FS_TYPE, 0);
 132                         if (!stmnt) {
 133                                 printf("Failed to statmount(%" PRIu64 ") in mount namespace(%" PRIu64 ")\n",
 134                                        (uint64_t)last_mnt_id, (uint64_t)info.mnt_ns_id);
 135                                 continue;
 136                         }
 137
 138                         printf("mnt_id:\t\t%" PRIu64 "\nmnt_parent_id:\t%" PRIu64 "\nfs_type:\t%s\nmnt_root:\t%s\nmnt_point:\t%s\nmnt_opts:\t%s\n\n",
 139                                (uint64_t)stmnt->mnt_id,
 140                                (uint64_t)stmnt->mnt_parent_id,
 141                                stmnt->str + stmnt->fs_type,
 142                                stmnt->str + stmnt->mnt_root,
 143                                stmnt->str + stmnt->mnt_point,
 144                                stmnt->str + stmnt->mnt_opts);
 145                         free(stmnt);
 146                 }
 147         }
 148
 149         exit(0);
 150 }