From b750101eb236130cf056c675997decbac904cc49 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 17:35:18 +0200 Subject: Adding upstream version 252.22. Signed-off-by: Daniel Baumann --- src/shared/mount-util.h | 143 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 143 insertions(+) create mode 100644 src/shared/mount-util.h (limited to 'src/shared/mount-util.h') diff --git a/src/shared/mount-util.h b/src/shared/mount-util.h new file mode 100644 index 0000000..8b07611 --- /dev/null +++ b/src/shared/mount-util.h @@ -0,0 +1,143 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ +#pragma once + +#include +#include +#include +#include + +#include "alloc-util.h" +#include "dissect-image.h" +#include "errno-util.h" +#include "macro.h" + +/* The limit used for /dev itself. 4MB should be enough since device nodes and symlinks don't + * consume any space and udev isn't supposed to create regular file either. There's no limit on the + * max number of inodes since such limit is hard to guess especially on large storage array + * systems. */ +#define TMPFS_LIMITS_DEV ",size=4m" + +/* The limit used for /dev in private namespaces. 4MB for contents of regular files. The number of + * inodes should be relatively low in private namespaces but for now use a 64k limit. */ +#define TMPFS_LIMITS_PRIVATE_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); + +int bind_remount_recursive_with_mountinfo(const char *prefix, unsigned long new_flags, unsigned long flags_mask, char **deny_list, FILE *proc_self_mountinfo); +static inline int bind_remount_recursive(const char *prefix, unsigned long new_flags, unsigned long flags_mask, char **deny_list) { + return bind_remount_recursive_with_mountinfo(prefix, new_flags, flags_mask, deny_list, NULL); +} + +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); + +DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(FILE*, endmntent, NULL); +#define _cleanup_endmntent_ _cleanup_(endmntentp) + +int mount_verbose_full( + int error_log_level, + const char *what, + const char *where, + const char *type, + unsigned long flags, + const char *options, + bool follow_symlink); + +static inline int mount_follow_verbose( + int error_log_level, + const char *what, + const char *where, + const char *type, + unsigned long flags, + const char *options) { + return mount_verbose_full(error_log_level, what, where, type, flags, options, true); +} + +static inline int mount_nofollow_verbose( + int error_log_level, + const char *what, + const char *where, + const char *type, + unsigned long flags, + const char *options) { + return mount_verbose_full(error_log_level, what, where, type, flags, options, false); +} + +int umount_verbose( + int error_log_level, + const char *where, + int flags); + +int mount_option_mangle( + const char *options, + unsigned long mount_flags, + unsigned long *ret_mount_flags, + char **ret_remaining_options); + +int mode_to_inaccessible_node(const char *runtime_dir, mode_t mode, char **dest); +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) { + PROTECT_ERRNO; + if (p) { + (void) umount_recursive(p, 0); + (void) rmdir(p); + } + return mfree(p); +} +DEFINE_TRIVIAL_CLEANUP_FUNC(char*, umount_and_rmdir_and_free); + +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); +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); + +int make_mount_point(const char *path); + +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); + +/* 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); +int make_mount_point_inode_from_path(const char *source, const char *dest, mode_t mode); -- cgit v1.2.3