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