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 <sys/stat.h>
   7 #include <unistd.h>
   8
   9 #include "alloc-util.h"
  10 #include "dissect-image.h"
  11 #include "errno-util.h"
  12 #include "macro.h"
  13
  14 /* 4MB for contents of regular files, 64k inodes for directories, symbolic links and device specials, using
  15  * large storage array systems as a baseline */
  16 #define TMPFS_LIMITS_DEV             ",size=4m,nr_inodes=64k"
  17
  18 /* Very little, if any use expected */
  19 #define TMPFS_LIMITS_EMPTY_OR_ALMOST ",size=4m,nr_inodes=1k"
  20 #define TMPFS_LIMITS_SYS             TMPFS_LIMITS_EMPTY_OR_ALMOST
  21 #define TMPFS_LIMITS_SYS_FS_CGROUP   TMPFS_LIMITS_EMPTY_OR_ALMOST
  22
  23 /* On an extremely small device with only 256MB of RAM, 20% of RAM should be enough for the re-execution of
  24  * PID1 because 16MB of free space is required. */
  25 #define TMPFS_LIMITS_RUN             ",size=20%,nr_inodes=800k"
  26
  27 /* The limit used for various nested tmpfs mounts, in particular for guests started by systemd-nspawn.
  28  * 10% of RAM (using 16GB of RAM as a baseline) translates to 400k inodes (assuming 4k each) and 25%
  29  * translates to 1M inodes.
  30  * (On the host, /tmp is configured through a .mount unit file.) */
  31 #define NESTED_TMPFS_LIMITS          ",size=10%,nr_inodes=400k"
  32
  33 /* More space for volatile root and /var */
  34 #define TMPFS_LIMITS_VAR             ",size=25%,nr_inodes=1m"
  35 #define TMPFS_LIMITS_ROOTFS          TMPFS_LIMITS_VAR
  36 #define TMPFS_LIMITS_VOLATILE_STATE  TMPFS_LIMITS_VAR
  37
  38 int mount_fd(const char *source, int target_fd, const char *filesystemtype, unsigned long mountflags, const void *data);
  39 int mount_nofollow(const char *source, const char *target, const char *filesystemtype, unsigned long mountflags, const void *data);
  40
  41 int repeat_unmount(const char *path, int flags);
  42 int umount_recursive(const char *target, int flags);
  43 int bind_remount_recursive(const char *prefix, unsigned long new_flags, unsigned long flags_mask, char **deny_list);
  44 int bind_remount_recursive_with_mountinfo(const char *prefix, unsigned long new_flags, unsigned long flags_mask, char **deny_list, FILE *proc_self_mountinfo);
  45 int bind_remount_one_with_mountinfo(const char *path, unsigned long new_flags, unsigned long flags_mask, FILE *proc_self_mountinfo);
  46
  47 int mount_move_root(const char *path);
  48
  49 DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(FILE*, endmntent, NULL);
  50 #define _cleanup_endmntent_ _cleanup_(endmntentp)
  51
  52 int mount_verbose_full(
  53                 int error_log_level,
  54                 const char *what,
  55                 const char *where,
  56                 const char *type,
  57                 unsigned long flags,
  58                 const char *options,
  59                 bool follow_symlink);
  60
  61 static inline int mount_follow_verbose(
  62                 int error_log_level,
  63                 const char *what,
  64                 const char *where,
  65                 const char *type,
  66                 unsigned long flags,
  67                 const char *options) {
  68         return mount_verbose_full(error_log_level, what, where, type, flags, options, true);
  69 }
  70
  71 static inline int mount_nofollow_verbose(
  72                 int error_log_level,
  73                 const char *what,
  74                 const char *where,
  75                 const char *type,
  76                 unsigned long flags,
  77                 const char *options) {
  78         return mount_verbose_full(error_log_level, what, where, type, flags, options, false);
  79 }
  80
  81 int umount_verbose(
  82                 int error_log_level,
  83                 const char *where,
  84                 int flags);
  85
  86 int mount_option_mangle(
  87                 const char *options,
  88                 unsigned long mount_flags,
  89                 unsigned long *ret_mount_flags,
  90                 char **ret_remaining_options);
  91
  92 int mode_to_inaccessible_node(const char *runtime_dir, mode_t mode, char **dest);
  93 int mount_flags_to_string(long unsigned flags, char **ret);
  94
  95 /* Useful for usage with _cleanup_(), unmounts, removes a directory and frees the pointer */
  96 static inline char* umount_and_rmdir_and_free(char *p) {
  97         PROTECT_ERRNO;
  98         if (p) {
  99                 (void) umount_recursive(p, 0);
 100                 (void) rmdir(p);
 101         }
 102         return mfree(p);
 103 }
 104 DEFINE_TRIVIAL_CLEANUP_FUNC(char*, umount_and_rmdir_and_free);
 105
 106 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);
 107 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);
 108
 109 int make_mount_point(const char *path);
 110
 111 int remount_idmap(const char *p, uid_t uid_shift, uid_t uid_range);
 112
 113 /* Creates a mount point (not parents) based on the source path or stat - ie, a file or a directory */
 114 int make_mount_point_inode_from_stat(const struct stat *st, const char *dest, mode_t mode);
 115 int make_mount_point_inode_from_path(const char *source, const char *dest, mode_t mode);