src/lxc/mount_utils.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #ifndef _GNU_SOURCE
   4 #define _GNU_SOURCE 1
   5 #endif
   6 #include <fcntl.h>
   7 #include <stdio.h>
   8 #include <stdlib.h>
   9 #include <sys/mount.h>
  10 #include <sys/stat.h>
  11 #include <sys/types.h>
  12
  13 #include "log.h"
  14 #include "macro.h"
  15 #include "memory_utils.h"
  16 #include "mount_utils.h"
  17 #include "syscall_numbers.h"
  18 #include "syscall_wrappers.h"
  19
  20 lxc_log_define(mount_utils, lxc);
  21
  22 int mnt_attributes_new(unsigned int old_flags, unsigned int *new_flags)
  23 {
  24         unsigned int flags = 0;
  25
  26         if (old_flags & MS_RDONLY) {
  27                 flags |= MOUNT_ATTR_RDONLY;
  28                 old_flags &= ~MS_RDONLY;
  29         }
  30
  31         if (old_flags & MS_NOSUID) {
  32                 flags |= MOUNT_ATTR_NOSUID;
  33                 old_flags &= ~MS_NOSUID;
  34         }
  35
  36         if (old_flags & MS_NODEV) {
  37                 flags |= MOUNT_ATTR_NODEV;
  38                 old_flags &= ~MS_NODEV;
  39         }
  40
  41         if (old_flags & MS_NOEXEC) {
  42                 flags |= MOUNT_ATTR_NOEXEC;
  43                 old_flags &= ~MS_NOEXEC;
  44         }
  45
  46         if (old_flags & MS_RELATIME) {
  47                 flags |= MOUNT_ATTR_RELATIME;
  48                 old_flags &= ~MS_RELATIME;
  49         }
  50
  51         if (old_flags & MS_NOATIME) {
  52                 flags |= MOUNT_ATTR_NOATIME;
  53                 old_flags &= ~MS_NOATIME;
  54         }
  55
  56         if (old_flags & MS_STRICTATIME) {
  57                 flags |= MOUNT_ATTR_STRICTATIME;
  58                 old_flags &= ~MS_STRICTATIME;
  59         }
  60
  61         if (old_flags & MS_NODIRATIME) {
  62                 flags |= MOUNT_ATTR_NODIRATIME;
  63                 old_flags &= ~MS_NODIRATIME;
  64         }
  65
  66         *new_flags |= flags;
  67         return old_flags;
  68 }
  69
  70 int mnt_attributes_old(unsigned int new_flags, unsigned int *old_flags)
  71 {
  72         unsigned int flags = 0;
  73
  74         if (new_flags & MOUNT_ATTR_RDONLY) {
  75                 flags |= MS_RDONLY;
  76                 new_flags &= ~MOUNT_ATTR_RDONLY;
  77         }
  78
  79         if (new_flags & MOUNT_ATTR_NOSUID) {
  80                 flags |= MS_NOSUID;
  81                 new_flags &= ~MOUNT_ATTR_NOSUID;
  82         }
  83
  84         if (new_flags & MS_NODEV) {
  85                 flags |= MOUNT_ATTR_NODEV;
  86                 new_flags &= ~MS_NODEV;
  87         }
  88
  89         if (new_flags & MOUNT_ATTR_NOEXEC) {
  90                 flags |= MS_NOEXEC;
  91                 new_flags &= ~MOUNT_ATTR_NOEXEC;
  92         }
  93
  94         if (new_flags & MS_RELATIME) {
  95                 flags |= MS_RELATIME;
  96                 new_flags &= ~MOUNT_ATTR_RELATIME;
  97         }
  98
  99         if (new_flags & MS_NOATIME) {
 100                 flags |= MS_NOATIME;
 101                 new_flags &= ~MOUNT_ATTR_NOATIME;
 102         }
 103
 104         if (new_flags & MS_STRICTATIME) {
 105                 flags |= MS_STRICTATIME;
 106                 new_flags &= ~MOUNT_ATTR_STRICTATIME;
 107         }
 108
 109         if (new_flags & MS_NODIRATIME) {
 110                 flags |= MS_NODIRATIME;
 111                 new_flags &= ~MOUNT_ATTR_NODIRATIME;
 112         }
 113
 114         *old_flags |= flags;
 115         return new_flags;
 116 }
 117
 118 int mount_filesystem(const char *fs_name, const char *path, unsigned int attr_flags)
 119 {
 120         __do_close int fsfd = -EBADF;
 121         unsigned int old_flags = 0;
 122
 123         fsfd = fsopen(fs_name, FSOPEN_CLOEXEC);
 124         if (fsfd >= 0) {
 125                 __do_close int mfd = -EBADF;
 126
 127                 if (fsconfig(fsfd, FSCONFIG_CMD_CREATE, NULL, NULL, 0))
 128                         return -1;
 129
 130                 mfd = fsmount(fsfd, FSMOUNT_CLOEXEC, attr_flags);
 131                 if (mfd < 0)
 132                         return -1;
 133
 134                 return move_mount(mfd, "", AT_FDCWD, path, MOVE_MOUNT_F_EMPTY_PATH);
 135         }
 136
 137         TRACE("Falling back to old mount api");
 138         mnt_attributes_old(attr_flags, &old_flags);
 139         return mount("none", path, fs_name, old_flags, NULL);
 140 }