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1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * sysctl.h: General linux system control interface
4 *
5 * Begun 24 March 1995, Stephen Tweedie
6 *
7 ****************************************************************
8 ****************************************************************
9 **
10 ** WARNING:
11 ** The values in this file are exported to user space via
12 ** the sysctl() binary interface. Do *NOT* change the
13 ** numbering of any existing values here, and do not change
14 ** any numbers within any one set of values. If you have to
15 ** redefine an existing interface, use a new number for it.
16 ** The kernel will then return -ENOTDIR to any application using
17 ** the old binary interface.
18 **
19 ****************************************************************
20 ****************************************************************
21 */
22#ifndef _LINUX_SYSCTL_H
23#define _LINUX_SYSCTL_H
24
25#include <linux/list.h>
26#include <linux/rcupdate.h>
27#include <linux/wait.h>
28#include <linux/rbtree.h>
29#include <linux/uidgid.h>
30#include <uapi/linux/sysctl.h>
31
32/* For the /proc/sys support */
33struct completion;
34struct ctl_table;
35struct nsproxy;
36struct ctl_table_root;
37struct ctl_table_header;
38struct ctl_dir;
39
40/* Keep the same order as in fs/proc/proc_sysctl.c */
41#define SYSCTL_ZERO ((void *)&sysctl_vals[0])
42#define SYSCTL_ONE ((void *)&sysctl_vals[1])
43#define SYSCTL_INT_MAX ((void *)&sysctl_vals[2])
44
45extern const int sysctl_vals[];
46
47typedef int proc_handler (struct ctl_table *ctl, int write,
48 void __user *buffer, size_t *lenp, loff_t *ppos);
49
50extern int proc_dostring(struct ctl_table *, int,
51 void __user *, size_t *, loff_t *);
52extern int proc_dointvec(struct ctl_table *, int,
53 void __user *, size_t *, loff_t *);
54extern int proc_douintvec(struct ctl_table *, int,
55 void __user *, size_t *, loff_t *);
56extern int proc_dointvec_minmax(struct ctl_table *, int,
57 void __user *, size_t *, loff_t *);
58extern int proc_douintvec_minmax(struct ctl_table *table, int write,
59 void __user *buffer, size_t *lenp,
60 loff_t *ppos);
61extern int proc_dointvec_jiffies(struct ctl_table *, int,
62 void __user *, size_t *, loff_t *);
63extern int proc_dointvec_userhz_jiffies(struct ctl_table *, int,
64 void __user *, size_t *, loff_t *);
65extern int proc_dointvec_ms_jiffies(struct ctl_table *, int,
66 void __user *, size_t *, loff_t *);
67extern int proc_doulongvec_minmax(struct ctl_table *, int,
68 void __user *, size_t *, loff_t *);
69extern int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int,
70 void __user *, size_t *, loff_t *);
71extern int proc_do_large_bitmap(struct ctl_table *, int,
72 void __user *, size_t *, loff_t *);
73extern int proc_do_static_key(struct ctl_table *table, int write,
74 void __user *buffer, size_t *lenp,
75 loff_t *ppos);
76
77/*
78 * Register a set of sysctl names by calling register_sysctl_table
79 * with an initialised array of struct ctl_table's. An entry with
80 * NULL procname terminates the table. table->de will be
81 * set up by the registration and need not be initialised in advance.
82 *
83 * sysctl names can be mirrored automatically under /proc/sys. The
84 * procname supplied controls /proc naming.
85 *
86 * The table's mode will be honoured both for sys_sysctl(2) and
87 * proc-fs access.
88 *
89 * Leaf nodes in the sysctl tree will be represented by a single file
90 * under /proc; non-leaf nodes will be represented by directories. A
91 * null procname disables /proc mirroring at this node.
92 *
93 * sysctl(2) can automatically manage read and write requests through
94 * the sysctl table. The data and maxlen fields of the ctl_table
95 * struct enable minimal validation of the values being written to be
96 * performed, and the mode field allows minimal authentication.
97 *
98 * There must be a proc_handler routine for any terminal nodes
99 * mirrored under /proc/sys (non-terminals are handled by a built-in
100 * directory handler). Several default handlers are available to
101 * cover common cases.
102 */
103
104/* Support for userspace poll() to watch for changes */
105struct ctl_table_poll {
106 atomic_t event;
107 wait_queue_head_t wait;
108};
109
110static inline void *proc_sys_poll_event(struct ctl_table_poll *poll)
111{
112 return (void *)(unsigned long)atomic_read(&poll->event);
113}
114
115#define __CTL_TABLE_POLL_INITIALIZER(name) { \
116 .event = ATOMIC_INIT(0), \
117 .wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.wait) }
118
119#define DEFINE_CTL_TABLE_POLL(name) \
120 struct ctl_table_poll name = __CTL_TABLE_POLL_INITIALIZER(name)
121
122/* A sysctl table is an array of struct ctl_table: */
123struct ctl_table {
124 const char *procname; /* Text ID for /proc/sys, or zero */
125 void *data;
126 int maxlen;
127 umode_t mode;
128 struct ctl_table *child; /* Deprecated */
129 proc_handler *proc_handler; /* Callback for text formatting */
130 struct ctl_table_poll *poll;
131 void *extra1;
132 void *extra2;
133} __randomize_layout;
134
135struct ctl_node {
136 struct rb_node node;
137 struct ctl_table_header *header;
138};
139
140/* struct ctl_table_header is used to maintain dynamic lists of
141 struct ctl_table trees. */
142struct ctl_table_header {
143 union {
144 struct {
145 struct ctl_table *ctl_table;
146 int used;
147 int count;
148 int nreg;
149 };
150 struct rcu_head rcu;
151 };
152 struct completion *unregistering;
153 struct ctl_table *ctl_table_arg;
154 struct ctl_table_root *root;
155 struct ctl_table_set *set;
156 struct ctl_dir *parent;
157 struct ctl_node *node;
158 struct hlist_head inodes; /* head for proc_inode->sysctl_inodes */
159};
160
161struct ctl_dir {
162 /* Header must be at the start of ctl_dir */
163 struct ctl_table_header header;
164 struct rb_root root;
165};
166
167struct ctl_table_set {
168 int (*is_seen)(struct ctl_table_set *);
169 struct ctl_dir dir;
170};
171
172struct ctl_table_root {
173 struct ctl_table_set default_set;
174 struct ctl_table_set *(*lookup)(struct ctl_table_root *root);
175 void (*set_ownership)(struct ctl_table_header *head,
176 struct ctl_table *table,
177 kuid_t *uid, kgid_t *gid);
178 int (*permissions)(struct ctl_table_header *head, struct ctl_table *table);
179};
180
181/* struct ctl_path describes where in the hierarchy a table is added */
182struct ctl_path {
183 const char *procname;
184};
185
186#ifdef CONFIG_SYSCTL
187
188void proc_sys_poll_notify(struct ctl_table_poll *poll);
189
190extern void setup_sysctl_set(struct ctl_table_set *p,
191 struct ctl_table_root *root,
192 int (*is_seen)(struct ctl_table_set *));
193extern void retire_sysctl_set(struct ctl_table_set *set);
194
195struct ctl_table_header *__register_sysctl_table(
196 struct ctl_table_set *set,
197 const char *path, struct ctl_table *table);
198struct ctl_table_header *__register_sysctl_paths(
199 struct ctl_table_set *set,
200 const struct ctl_path *path, struct ctl_table *table);
201struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table);
202struct ctl_table_header *register_sysctl_table(struct ctl_table * table);
203struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
204 struct ctl_table *table);
205
206void unregister_sysctl_table(struct ctl_table_header * table);
207
208extern int sysctl_init(void);
209
210extern struct ctl_table sysctl_mount_point[];
211
212#else /* CONFIG_SYSCTL */
213static inline struct ctl_table_header *register_sysctl_table(struct ctl_table * table)
214{
215 return NULL;
216}
217
218static inline struct ctl_table_header *register_sysctl_paths(
219 const struct ctl_path *path, struct ctl_table *table)
220{
221 return NULL;
222}
223
224static inline struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table)
225{
226 return NULL;
227}
228
229static inline void unregister_sysctl_table(struct ctl_table_header * table)
230{
231}
232
233static inline void setup_sysctl_set(struct ctl_table_set *p,
234 struct ctl_table_root *root,
235 int (*is_seen)(struct ctl_table_set *))
236{
237}
238
239#endif /* CONFIG_SYSCTL */
240
241int sysctl_max_threads(struct ctl_table *table, int write,
242 void __user *buffer, size_t *lenp, loff_t *ppos);
243
244#endif /* _LINUX_SYSCTL_H */