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