mount-util: introduce remount_sysfs()

[thirdparty/systemd.git] / src / shared / mount-util.h

diff --git a/src/shared/mount-util.h b/src/shared/mount-util.h
index d9fb801e6109582f8efd5bf831ad8c09436fb461..84ea4b6392773f388e132b7f0c5f877ccd1c9043 100644 (file)
--- a/src/shared/mount-util.h
+++ b/src/shared/mount-util.h
@@ -11,33 +11,6 @@
 #include "errno-util.h"
 #include "macro.h"
 
-/* 4MB for contents of regular files, 64k inodes for directories, symbolic links and device specials, using
- * large storage array systems as a baseline */
-#define TMPFS_LIMITS_DEV             ",size=4m,nr_inodes=64k"
-
-/* Very little, if any use expected */
-#define TMPFS_LIMITS_EMPTY_OR_ALMOST ",size=4m,nr_inodes=1k"
-#define TMPFS_LIMITS_SYS             TMPFS_LIMITS_EMPTY_OR_ALMOST
-#define TMPFS_LIMITS_SYS_FS_CGROUP   TMPFS_LIMITS_EMPTY_OR_ALMOST
-
-/* On an extremely small device with only 256MB of RAM, 20% of RAM should be enough for the re-execution of
- * PID1 because 16MB of free space is required. */
-#define TMPFS_LIMITS_RUN             ",size=20%,nr_inodes=800k"
-
-/* The limit used for various nested tmpfs mounts, in particular for guests started by systemd-nspawn.
- * 10% of RAM (using 16GB of RAM as a baseline) translates to 400k inodes (assuming 4k each) and 25%
- * translates to 1M inodes.
- * (On the host, /tmp is configured through a .mount unit file.) */
-#define NESTED_TMPFS_LIMITS          ",size=10%,nr_inodes=400k"
-
-/* More space for volatile root and /var */
-#define TMPFS_LIMITS_VAR             ",size=25%,nr_inodes=1m"
-#define TMPFS_LIMITS_ROOTFS          TMPFS_LIMITS_VAR
-#define TMPFS_LIMITS_VOLATILE_STATE  TMPFS_LIMITS_VAR
-
-int mount_fd(const char *source, int target_fd, const char *filesystemtype, unsigned long mountflags, const void *data);
-int mount_nofollow(const char *source, const char *target, const char *filesystemtype, unsigned long mountflags, const void *data);
-
 int repeat_unmount(const char *path, int flags);
 int umount_recursive(const char *target, int flags);
 
@@ -48,7 +21,7 @@ static inline int bind_remount_recursive(const char *prefix, unsigned long new_f
 
 int bind_remount_one_with_mountinfo(const char *path, unsigned long new_flags, unsigned long flags_mask, FILE *proc_self_mountinfo);
 
-int mount_move_root(const char *path);
+int mount_switch_root(const char *path, unsigned long mount_propagation_flag);
 
 DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(FILE*, endmntent, NULL);
 #define _cleanup_endmntent_ _cleanup_(endmntentp)
@@ -94,7 +67,7 @@ int mount_option_mangle(
                 char **ret_remaining_options);
 
 int mode_to_inaccessible_node(const char *runtime_dir, mode_t mode, char **dest);
-int mount_flags_to_string(long unsigned flags, char **ret);
+int mount_flags_to_string(unsigned long flags, char **ret);
 
 /* Useful for usage with _cleanup_(), unmounts, removes a directory and frees the pointer */
 static inline char* umount_and_rmdir_and_free(char *p) {
@@ -112,7 +85,33 @@ int mount_image_in_namespace(pid_t target, const char *propagate_path, const cha
 
 int make_mount_point(const char *path);
 
-int remount_idmap(const char *p, uid_t uid_shift, uid_t uid_range);
+typedef enum RemountIdmapping {
+        REMOUNT_IDMAPPING_NONE,
+        /* Include a mapping from UID_MAPPED_ROOT (i.e. UID 2^31-2) on the backing fs to UID 0 on the
+         * uidmapped fs. This is useful to ensure that the host root user can safely add inodes to the
+         * uidmapped fs (which otherwise wouldn't work as the host root user is not defined on the uidmapped
+         * mount and any attempts to create inodes will then be refused with EOVERFLOW). The idea is that
+         * these inodes are quickly re-chown()ed to more suitable UIDs/GIDs. Any code that intends to be able
+         * to add inodes to file systems mapped this way should set this flag, but given it comes with
+         * certain security implications defaults to off, and requires explicit opt-in. */
+        REMOUNT_IDMAPPING_HOST_ROOT,
+        /* Define a mapping from root user within the container to the owner of the bind mounted directory.
+         * This ensure no root-owned files will be written in a bind-mounted directory owned by a different
+         * user. No other users are mapped. */
+        REMOUNT_IDMAPPING_HOST_OWNER,
+        _REMOUNT_IDMAPPING_MAX,
+        _REMOUNT_IDMAPPING_INVALID = -EINVAL,
+} RemountIdmapping;
+
+int remount_idmap(const char *p, uid_t uid_shift, uid_t uid_range, uid_t owner, RemountIdmapping idmapping);
+
+int remount_and_move_sub_mounts(
+                const char *what,
+                const char *where,
+                const char *type,
+                unsigned long flags,
+                const char *options);
+int remount_sysfs(const char *where);
 
 /* Creates a mount point (not parents) based on the source path or stat - ie, a file or a directory */
 int make_mount_point_inode_from_stat(const struct stat *st, const char *dest, mode_t mode);