src/shared/mount-util.h

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2 #pragma once
   3
   4 #include <mntent.h>
   5 #include <stdio.h>
   6 #include <unistd.h>
   7
   8 #include "alloc-util.h"
   9 #include "dissect-image.h"
  10 #include "errno-util.h"
  11 #include "macro.h"
  12
  13 /* 4MB for contents of regular files, 64k inodes for directories, symbolic links and device specials, using
  14  * large storage array systems as a baseline */
  15 #define TMPFS_LIMITS_DEV             ",size=4m,nr_inodes=64k"
  16
  17 /* Very little, if any use expected */
  18 #define TMPFS_LIMITS_EMPTY_OR_ALMOST ",size=4m,nr_inodes=1k"
  19 #define TMPFS_LIMITS_SYS             TMPFS_LIMITS_EMPTY_OR_ALMOST
  20 #define TMPFS_LIMITS_SYS_FS_CGROUP   TMPFS_LIMITS_EMPTY_OR_ALMOST
  21
  22 /* On an extremely small device with only 256MB of RAM, 20% of RAM should be enough for the re-execution of
  23  * PID1 because 16MB of free space is required. */
  24 #define TMPFS_LIMITS_RUN             ",size=20%,nr_inodes=800k"
  25
  26 /* The limit used for various nested tmpfs mounts, in particular for guests started by systemd-nspawn.
  27  * 10% of RAM (using 16GB of RAM as a baseline) translates to 400k inodes (assuming 4k each) and 25%
  28  * translates to 1M inodes.
  29  * (On the host, /tmp is configured through a .mount unit file.) */
  30 #define NESTED_TMPFS_LIMITS          ",size=10%,nr_inodes=400k"
  31
  32 /* More space for volatile root and /var */
  33 #define TMPFS_LIMITS_VAR             ",size=25%,nr_inodes=1m"
  34 #define TMPFS_LIMITS_ROOTFS          TMPFS_LIMITS_VAR
  35 #define TMPFS_LIMITS_VOLATILE_STATE  TMPFS_LIMITS_VAR
  36
  37 int mount_fd(const char *source, int target_fd, const char *filesystemtype, unsigned long mountflags, const void *data);
  38 int mount_nofollow(const char *source, const char *target, const char *filesystemtype, unsigned long mountflags, const void *data);
  39
  40 int repeat_unmount(const char *path, int flags);
  41 int umount_recursive(const char *target, int flags);
  42 int bind_remount_recursive(const char *prefix, unsigned long new_flags, unsigned long flags_mask, char **deny_list);
  43 int bind_remount_recursive_with_mountinfo(const char *prefix, unsigned long new_flags, unsigned long flags_mask, char **deny_list, FILE *proc_self_mountinfo);
  44 int bind_remount_one_with_mountinfo(const char *path, unsigned long new_flags, unsigned long flags_mask, FILE *proc_self_mountinfo);
  45
  46 int mount_move_root(const char *path);
  47
  48 DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(FILE*, endmntent, NULL);
  49 #define _cleanup_endmntent_ _cleanup_(endmntentp)
  50
  51 int mount_verbose_full(
  52                 int error_log_level,
  53                 const char *what,
  54                 const char *where,
  55                 const char *type,
  56                 unsigned long flags,
  57                 const char *options,
  58                 bool follow_symlink);
  59
  60 static inline int mount_follow_verbose(
  61                 int error_log_level,
  62                 const char *what,
  63                 const char *where,
  64                 const char *type,
  65                 unsigned long flags,
  66                 const char *options) {
  67         return mount_verbose_full(error_log_level, what, where, type, flags, options, true);
  68 }
  69
  70 static inline int mount_nofollow_verbose(
  71                 int error_log_level,
  72                 const char *what,
  73                 const char *where,
  74                 const char *type,
  75                 unsigned long flags,
  76                 const char *options) {
  77         return mount_verbose_full(error_log_level, what, where, type, flags, options, false);
  78 }
  79
  80 int umount_verbose(
  81                 int error_log_level,
  82                 const char *where,
  83                 int flags);
  84
  85 int mount_option_mangle(
  86                 const char *options,
  87                 unsigned long mount_flags,
  88                 unsigned long *ret_mount_flags,
  89                 char **ret_remaining_options);
  90
  91 int mode_to_inaccessible_node(const char *runtime_dir, mode_t mode, char **dest);
  92
  93 /* Useful for usage with _cleanup_(), unmounts, removes a directory and frees the pointer */
  94 static inline char* umount_and_rmdir_and_free(char *p) {
  95         PROTECT_ERRNO;
  96         if (p) {
  97                 (void) umount_recursive(p, 0);
  98                 (void) rmdir(p);
  99         }
 100         return mfree(p);
 101 }
 102 DEFINE_TRIVIAL_CLEANUP_FUNC(char*, umount_and_rmdir_and_free);
 103
 104 int bind_mount_in_namespace(pid_t target, const char *propagate_path, const char *incoming_path, const char *src, const char *dest, bool read_only, bool make_file_or_directory);
 105 int mount_image_in_namespace(pid_t target, const char *propagate_path, const char *incoming_path, const char *src, const char *dest, bool read_only, bool make_file_or_directory, const MountOptions *options);
 106
 107 int make_mount_point(const char *path);
 108
 109 int remount_idmap(const char *p, uid_t uid_shift, uid_t uid_range);