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 #include "pidref.h"
  14
  15 int repeat_unmount(const char *path, int flags);
  16
  17 int umount_recursive_full(const char *target, int flags, char **keep);
  18
  19 static inline int umount_recursive(const char *target, int flags) {
  20         return umount_recursive_full(target, flags, NULL);
  21 }
  22
  23 int bind_remount_recursive_with_mountinfo(const char *prefix, unsigned long new_flags, unsigned long flags_mask, char **deny_list, FILE *proc_self_mountinfo);
  24 static inline int bind_remount_recursive(const char *prefix, unsigned long new_flags, unsigned long flags_mask, char **deny_list) {
  25         return bind_remount_recursive_with_mountinfo(prefix, new_flags, flags_mask, deny_list, NULL);
  26 }
  27
  28 int bind_remount_one_with_mountinfo(const char *path, unsigned long new_flags, unsigned long flags_mask, FILE *proc_self_mountinfo);
  29
  30 int mount_switch_root_full(const char *path, unsigned long mount_propagation_flag, bool force_ms_move);
  31 static inline int mount_switch_root(const char *path, unsigned long mount_propagation_flag) {
  32         return mount_switch_root_full(path, mount_propagation_flag, false);
  33 }
  34
  35 DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(FILE*, endmntent, NULL);
  36 #define _cleanup_endmntent_ _cleanup_(endmntentp)
  37
  38 int mount_verbose_full(
  39                 int error_log_level,
  40                 const char *what,
  41                 const char *where,
  42                 const char *type,
  43                 unsigned long flags,
  44                 const char *options,
  45                 bool follow_symlink);
  46
  47 static inline int mount_follow_verbose(
  48                 int error_log_level,
  49                 const char *what,
  50                 const char *where,
  51                 const char *type,
  52                 unsigned long flags,
  53                 const char *options) {
  54         return mount_verbose_full(error_log_level, what, where, type, flags, options, true);
  55 }
  56
  57 static inline int mount_nofollow_verbose(
  58                 int error_log_level,
  59                 const char *what,
  60                 const char *where,
  61                 const char *type,
  62                 unsigned long flags,
  63                 const char *options) {
  64         return mount_verbose_full(error_log_level, what, where, type, flags, options, false);
  65 }
  66
  67 int umount_verbose(
  68                 int error_log_level,
  69                 const char *where,
  70                 int flags);
  71
  72 int mount_exchange_graceful(int fsmount_fd, const char *dest, bool mount_beneath);
  73
  74 int mount_option_mangle(
  75                 const char *options,
  76                 unsigned long mount_flags,
  77                 unsigned long *ret_mount_flags,
  78                 char **ret_remaining_options);
  79
  80 int mode_to_inaccessible_node(const char *runtime_dir, mode_t mode, char **dest);
  81 int mount_flags_to_string(unsigned long flags, char **ret);
  82
  83 /* Useful for usage with _cleanup_(), unmounts, removes a directory and frees the pointer */
  84 static inline char* umount_and_rmdir_and_free(char *p) {
  85         PROTECT_ERRNO;
  86         if (p) {
  87                 (void) umount_recursive(p, 0);
  88                 (void) rmdir(p);
  89         }
  90         return mfree(p);
  91 }
  92 DEFINE_TRIVIAL_CLEANUP_FUNC(char*, umount_and_rmdir_and_free);
  93
  94 static inline char *umount_and_free(char *p) {
  95         PROTECT_ERRNO;
  96         if (p)
  97                 (void) umount_recursive(p, 0);
  98         return mfree(p);
  99 }
 100 DEFINE_TRIVIAL_CLEANUP_FUNC(char*, umount_and_free);
 101
 102 int bind_mount_in_namespace(PidRef *target, const char *propagate_path, const char *incoming_path, const char *src, const char *dest, bool read_only, bool make_file_or_directory);
 103 int mount_image_in_namespace(PidRef *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, const ImagePolicy *image_policy);
 104
 105 int make_mount_point(const char *path);
 106 int fd_make_mount_point(int fd);
 107
 108 typedef enum RemountIdmapping {
 109         REMOUNT_IDMAPPING_NONE,
 110         /* Include a mapping from UID_MAPPED_ROOT (i.e. UID 2^31-2) on the backing fs to UID 0 on the
 111          * uidmapped fs. This is useful to ensure that the host root user can safely add inodes to the
 112          * uidmapped fs (which otherwise wouldn't work as the host root user is not defined on the uidmapped
 113          * mount and any attempts to create inodes will then be refused with EOVERFLOW). The idea is that
 114          * these inodes are quickly re-chown()ed to more suitable UIDs/GIDs. Any code that intends to be able
 115          * to add inodes to file systems mapped this way should set this flag, but given it comes with
 116          * certain security implications defaults to off, and requires explicit opt-in. */
 117         REMOUNT_IDMAPPING_HOST_ROOT,
 118         /* Define a mapping from root user within the container to the owner of the bind mounted directory.
 119          * This ensure no root-owned files will be written in a bind-mounted directory owned by a different
 120          * user. No other users are mapped. */
 121         REMOUNT_IDMAPPING_HOST_OWNER,
 122         _REMOUNT_IDMAPPING_MAX,
 123         _REMOUNT_IDMAPPING_INVALID = -EINVAL,
 124 } RemountIdmapping;
 125
 126 int make_userns(uid_t uid_shift, uid_t uid_range, uid_t owner, RemountIdmapping idmapping);
 127 int remount_idmap_fd(const char *p, int userns_fd);
 128 int remount_idmap(const char *p, uid_t uid_shift, uid_t uid_range, uid_t owner, RemountIdmapping idmapping);
 129
 130 int bind_mount_submounts(
 131                 const char *source,
 132                 const char *target);
 133
 134 /* Creates a mount point (not parents) based on the source path or stat - ie, a file or a directory */
 135 int make_mount_point_inode_from_stat(const struct stat *st, const char *dest, mode_t mode);
 136 int make_mount_point_inode_from_path(const char *source, const char *dest, mode_t mode);
 137
 138 int trigger_automount_at(int dir_fd, const char *path);
 139
 140 unsigned long credentials_fs_mount_flags(bool ro);
 141 int mount_credentials_fs(const char *path, size_t size, bool ro);
 142
 143 int make_fsmount(int error_log_level, const char *what, const char *type, unsigned long flags, const char *options, int userns_fd);