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 /* 4MB for contents of regular files, 1m inodes for directories, symbolic links and device nodes, using
15 * large storage array systems as a baseline */
16 #define TMPFS_LIMITS_DEV ",size=4m,nr_inodes=1m"
17
18 /* Very little, if any use expected */
19 #define TMPFS_LIMITS_EMPTY_OR_ALMOST ",size=4m,nr_inodes=1k"
20 #define TMPFS_LIMITS_SYS TMPFS_LIMITS_EMPTY_OR_ALMOST
21 #define TMPFS_LIMITS_SYS_FS_CGROUP TMPFS_LIMITS_EMPTY_OR_ALMOST
22
23 /* On an extremely small device with only 256MB of RAM, 20% of RAM should be enough for the re-execution of
24 * PID1 because 16MB of free space is required. */
25 #define TMPFS_LIMITS_RUN ",size=20%,nr_inodes=800k"
26
27 /* The limit used for various nested tmpfs mounts, in particular for guests started by systemd-nspawn.
28 * 10% of RAM (using 16GB of RAM as a baseline) translates to 400k inodes (assuming 4k each) and 25%
29 * translates to 1M inodes.
30 * (On the host, /tmp is configured through a .mount unit file.) */
31 #define NESTED_TMPFS_LIMITS ",size=10%,nr_inodes=400k"
32
33 /* More space for volatile root and /var */
34 #define TMPFS_LIMITS_VAR ",size=25%,nr_inodes=1m"
35 #define TMPFS_LIMITS_ROOTFS TMPFS_LIMITS_VAR
36 #define TMPFS_LIMITS_VOLATILE_STATE TMPFS_LIMITS_VAR
37
38 int mount_fd(const char *source, int target_fd, const char *filesystemtype, unsigned long mountflags, const void *data);
39 int mount_nofollow(const char *source, const char *target, const char *filesystemtype, unsigned long mountflags, const void *data);
40
41 int repeat_unmount(const char *path, int flags);
42 int umount_recursive(const char *target, int flags);
43
44 int bind_remount_recursive_with_mountinfo(const char *prefix, unsigned long new_flags, unsigned long flags_mask, char **deny_list, FILE *proc_self_mountinfo);
bind_remount_recursive(const char * prefix,unsigned long new_flags,unsigned long flags_mask,char ** deny_list)45 static inline int bind_remount_recursive(const char *prefix, unsigned long new_flags, unsigned long flags_mask, char **deny_list) {
46 return bind_remount_recursive_with_mountinfo(prefix, new_flags, flags_mask, deny_list, NULL);
47 }
48
49 int bind_remount_one_with_mountinfo(const char *path, unsigned long new_flags, unsigned long flags_mask, FILE *proc_self_mountinfo);
50
51 int mount_move_root(const char *path);
52
53 DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(FILE*, endmntent, NULL);
54 #define _cleanup_endmntent_ _cleanup_(endmntentp)
55
56 int mount_verbose_full(
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 bool follow_symlink);
64
mount_follow_verbose(int error_log_level,const char * what,const char * where,const char * type,unsigned long flags,const char * options)65 static inline int mount_follow_verbose(
66 int error_log_level,
67 const char *what,
68 const char *where,
69 const char *type,
70 unsigned long flags,
71 const char *options) {
72 return mount_verbose_full(error_log_level, what, where, type, flags, options, true);
73 }
74
mount_nofollow_verbose(int error_log_level,const char * what,const char * where,const char * type,unsigned long flags,const char * options)75 static inline int mount_nofollow_verbose(
76 int error_log_level,
77 const char *what,
78 const char *where,
79 const char *type,
80 unsigned long flags,
81 const char *options) {
82 return mount_verbose_full(error_log_level, what, where, type, flags, options, false);
83 }
84
85 int umount_verbose(
86 int error_log_level,
87 const char *where,
88 int flags);
89
90 int mount_option_mangle(
91 const char *options,
92 unsigned long mount_flags,
93 unsigned long *ret_mount_flags,
94 char **ret_remaining_options);
95
96 int mode_to_inaccessible_node(const char *runtime_dir, mode_t mode, char **dest);
97 int mount_flags_to_string(unsigned long flags, char **ret);
98
99 /* Useful for usage with _cleanup_(), unmounts, removes a directory and frees the pointer */
umount_and_rmdir_and_free(char * p)100 static inline char* umount_and_rmdir_and_free(char *p) {
101 PROTECT_ERRNO;
102 if (p) {
103 (void) umount_recursive(p, 0);
104 (void) rmdir(p);
105 }
106 return mfree(p);
107 }
108 DEFINE_TRIVIAL_CLEANUP_FUNC(char*, umount_and_rmdir_and_free);
109
110 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);
111 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);
112
113 int make_mount_point(const char *path);
114
115 typedef enum RemountIdmapFlags {
116 /* Include a mapping from UID_MAPPED_ROOT (i.e. UID 2^31-2) on the backing fs to UID 0 on the
117 * uidmapped fs. This is useful to ensure that the host root user can safely add inodes to the
118 * uidmapped fs (which otherwise wouldn't work as the host root user is not defined on the uidmapped
119 * mount and any attempts to create inodes will then be refused with EOVERFLOW). The idea is that
120 * these inodes are quickly re-chown()ed to more suitable UIDs/GIDs. Any code that intends to be able
121 * to add inodes to file systems mapped this way should set this flag, but given it comes with
122 * certain security implications defaults to off, and requires explicit opt-in. */
123 REMOUNT_IDMAP_HOST_ROOT = 1 << 0,
124 } RemountIdmapFlags;
125
126 int remount_idmap(const char *p, uid_t uid_shift, uid_t uid_range, RemountIdmapFlags flags);
127
128 /* Creates a mount point (not parents) based on the source path or stat - ie, a file or a directory */
129 int make_mount_point_inode_from_stat(const struct stat *st, const char *dest, mode_t mode);
130 int make_mount_point_inode_from_path(const char *source, const char *dest, mode_t mode);
131