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 int bind_remount_one(const char *path, unsigned long new_flags, unsigned long flags_mask);
  30
  31 int mount_switch_root_full(const char *path, unsigned long mount_propagation_flag, bool force_ms_move);
  32 static inline int mount_switch_root(const char *path, unsigned long mount_propagation_flag) {
  33         return mount_switch_root_full(path, mount_propagation_flag, false);
  34 }
  35
  36 DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(FILE*, endmntent, NULL);
  37 #define _cleanup_endmntent_ _cleanup_(endmntentp)
  38
  39 int mount_verbose_full(
  40                 int error_log_level,
  41                 const char *what,
  42                 const char *where,
  43                 const char *type,
  44                 unsigned long flags,
  45                 const char *options,
  46                 bool follow_symlink);
  47
  48 static inline int mount_follow_verbose(
  49                 int error_log_level,
  50                 const char *what,
  51                 const char *where,
  52                 const char *type,
  53                 unsigned long flags,
  54                 const char *options) {
  55         return mount_verbose_full(error_log_level, what, where, type, flags, options, true);
  56 }
  57
  58 static inline int mount_nofollow_verbose(
  59                 int error_log_level,
  60                 const char *what,
  61                 const char *where,
  62                 const char *type,
  63                 unsigned long flags,
  64                 const char *options) {
  65         return mount_verbose_full(error_log_level, what, where, type, flags, options, false);
  66 }
  67
  68 int umount_verbose(
  69                 int error_log_level,
  70                 const char *where,
  71                 int flags);
  72
  73 int mount_exchange_graceful(int fsmount_fd, const char *dest, bool mount_beneath);
  74
  75 int mount_option_mangle(
  76                 const char *options,
  77                 unsigned long mount_flags,
  78                 unsigned long *ret_mount_flags,
  79                 char **ret_remaining_options);
  80
  81 int mode_to_inaccessible_node(const char *runtime_dir, mode_t mode, char **dest);
  82 int mount_flags_to_string(unsigned long flags, char **ret);
  83
  84 /* Useful for usage with _cleanup_(), unmounts, removes a directory and frees the pointer */
  85 static inline char* umount_and_rmdir_and_free(char *p) {
  86         PROTECT_ERRNO;
  87         if (p) {
  88                 (void) umount_recursive(p, 0);
  89                 (void) rmdir(p);
  90         }
  91         return mfree(p);
  92 }
  93 DEFINE_TRIVIAL_CLEANUP_FUNC(char*, umount_and_rmdir_and_free);
  94
  95 static inline char *umount_and_free(char *p) {
  96         PROTECT_ERRNO;
  97         if (p)
  98                 (void) umount_recursive(p, 0);
  99         return mfree(p);
 100 }
 101 DEFINE_TRIVIAL_CLEANUP_FUNC(char*, umount_and_free);
 102
 103 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);
 104 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);
 105
 106 int make_mount_point(const char *path);
 107 int fd_make_mount_point(int fd);
 108
 109 typedef enum RemountIdmapping {
 110         REMOUNT_IDMAPPING_NONE,
 111         /* Include a mapping from UID_MAPPED_ROOT (i.e. UID 2^31-2) on the backing fs to UID 0 on the
 112          * uidmapped fs. This is useful to ensure that the host root user can safely add inodes to the
 113          * uidmapped fs (which otherwise wouldn't work as the host root user is not defined on the uidmapped
 114          * mount and any attempts to create inodes will then be refused with EOVERFLOW). The idea is that
 115          * these inodes are quickly re-chown()ed to more suitable UIDs/GIDs. Any code that intends to be able
 116          * to add inodes to file systems mapped this way should set this flag, but given it comes with
 117          * certain security implications defaults to off, and requires explicit opt-in. */
 118         REMOUNT_IDMAPPING_HOST_ROOT,
 119         /* Define a mapping from root user within the container to the owner of the bind mounted directory.
 120          * This ensures no root-owned files will be written in a bind-mounted directory owned by a different
 121          * user. No other users are mapped. */
 122         REMOUNT_IDMAPPING_HOST_OWNER,
 123         /* Define a mapping from bind-target owner within the container to the host owner of the bind mounted
 124          * directory. No other users are mapped. */
 125         REMOUNT_IDMAPPING_HOST_OWNER_TO_TARGET_OWNER,
 126         _REMOUNT_IDMAPPING_MAX,
 127         _REMOUNT_IDMAPPING_INVALID = -EINVAL,
 128 } RemountIdmapping;
 129
 130 int make_userns(uid_t uid_shift, uid_t uid_range, uid_t host_owner, uid_t dest_owner, RemountIdmapping idmapping);
 131 int remount_idmap_fd(char **p, int userns_fd);
 132 int remount_idmap(char **p, uid_t uid_shift, uid_t uid_range, uid_t host_owner, uid_t dest_owner, RemountIdmapping idmapping);
 133
 134 int bind_mount_submounts(
 135                 const char *source,
 136                 const char *target);
 137
 138 /* Creates a mount point (not parents) based on the source path or stat - ie, a file or a directory */
 139 int make_mount_point_inode_from_stat(const struct stat *st, const char *dest, mode_t mode);
 140 int make_mount_point_inode_from_path(const char *source, const char *dest, mode_t mode);
 141
 142 int trigger_automount_at(int dir_fd, const char *path);
 143
 144 unsigned long credentials_fs_mount_flags(bool ro);
 145 int mount_credentials_fs(const char *path, size_t size, bool ro);
 146
 147 int make_fsmount(int error_log_level, const char *what, const char *type, unsigned long flags, const char *options, int userns_fd);