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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, void *buffer,
48 size_t *lenp, loff_t *ppos);
49
50int proc_dostring(struct ctl_table *, int, void *, size_t *, loff_t *);
51int proc_dointvec(struct ctl_table *, int, void *, size_t *, loff_t *);
52int proc_douintvec(struct ctl_table *, int, void *, size_t *, loff_t *);
53int proc_dointvec_minmax(struct ctl_table *, int, void *, size_t *, loff_t *);
54int proc_douintvec_minmax(struct ctl_table *table, int write, void *buffer,
55 size_t *lenp, loff_t *ppos);
56int proc_dou8vec_minmax(struct ctl_table *table, int write, void *buffer,
57 size_t *lenp, loff_t *ppos);
58int proc_dointvec_jiffies(struct ctl_table *, int, void *, size_t *, loff_t *);
59int proc_dointvec_userhz_jiffies(struct ctl_table *, int, void *, size_t *,
60 loff_t *);
61int proc_dointvec_ms_jiffies(struct ctl_table *, int, void *, size_t *,
62 loff_t *);
63int proc_doulongvec_minmax(struct ctl_table *, int, void *, size_t *, loff_t *);
64int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int, void *,
65 size_t *, loff_t *);
66int proc_do_large_bitmap(struct ctl_table *, int, void *, size_t *, loff_t *);
67int proc_do_static_key(struct ctl_table *table, int write, void *buffer,
68 size_t *lenp, loff_t *ppos);
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 for proc-fs access.
80 *
81 * Leaf nodes in the sysctl tree will be represented by a single file
82 * under /proc; non-leaf nodes will be represented by directories. A
83 * null procname disables /proc mirroring at this node.
84 *
85 * The data and maxlen fields of the ctl_table
86 * struct enable minimal validation of the values being written to be
87 * performed, and the mode field allows minimal authentication.
88 *
89 * There must be a proc_handler routine for any terminal nodes
90 * mirrored under /proc/sys (non-terminals are handled by a built-in
91 * directory handler). Several default handlers are available to
92 * cover common cases.
93 */
94
95/* Support for userspace poll() to watch for changes */
96struct ctl_table_poll {
97 atomic_t event;
98 wait_queue_head_t wait;
99};
100
101static inline void *proc_sys_poll_event(struct ctl_table_poll *poll)
102{
103 return (void *)(unsigned long)atomic_read(&poll->event);
104}
105
106#define __CTL_TABLE_POLL_INITIALIZER(name) { \
107 .event = ATOMIC_INIT(0), \
108 .wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.wait) }
109
110#define DEFINE_CTL_TABLE_POLL(name) \
111 struct ctl_table_poll name = __CTL_TABLE_POLL_INITIALIZER(name)
112
113/* A sysctl table is an array of struct ctl_table: */
114struct ctl_table {
115 const char *procname; /* Text ID for /proc/sys, or zero */
116 void *data;
117 int maxlen;
118 umode_t mode;
119 struct ctl_table *child; /* Deprecated */
120 proc_handler *proc_handler; /* Callback for text formatting */
121 struct ctl_table_poll *poll;
122 void *extra1;
123 void *extra2;
124} __randomize_layout;
125
126struct ctl_node {
127 struct rb_node node;
128 struct ctl_table_header *header;
129};
130
131/* struct ctl_table_header is used to maintain dynamic lists of
132 struct ctl_table trees. */
133struct ctl_table_header {
134 union {
135 struct {
136 struct ctl_table *ctl_table;
137 int used;
138 int count;
139 int nreg;
140 };
141 struct rcu_head rcu;
142 };
143 struct completion *unregistering;
144 struct ctl_table *ctl_table_arg;
145 struct ctl_table_root *root;
146 struct ctl_table_set *set;
147 struct ctl_dir *parent;
148 struct ctl_node *node;
149 struct hlist_head inodes; /* head for proc_inode->sysctl_inodes */
150};
151
152struct ctl_dir {
153 /* Header must be at the start of ctl_dir */
154 struct ctl_table_header header;
155 struct rb_root root;
156};
157
158struct ctl_table_set {
159 int (*is_seen)(struct ctl_table_set *);
160 struct ctl_dir dir;
161};
162
163struct ctl_table_root {
164 struct ctl_table_set default_set;
165 struct ctl_table_set *(*lookup)(struct ctl_table_root *root);
166 void (*set_ownership)(struct ctl_table_header *head,
167 struct ctl_table *table,
168 kuid_t *uid, kgid_t *gid);
169 int (*permissions)(struct ctl_table_header *head, struct ctl_table *table);
170};
171
172/* struct ctl_path describes where in the hierarchy a table is added */
173struct ctl_path {
174 const char *procname;
175};
176
177#ifdef CONFIG_SYSCTL
178
179void proc_sys_poll_notify(struct ctl_table_poll *poll);
180
181extern void setup_sysctl_set(struct ctl_table_set *p,
182 struct ctl_table_root *root,
183 int (*is_seen)(struct ctl_table_set *));
184extern void retire_sysctl_set(struct ctl_table_set *set);
185
186struct ctl_table_header *__register_sysctl_table(
187 struct ctl_table_set *set,
188 const char *path, struct ctl_table *table);
189struct ctl_table_header *__register_sysctl_paths(
190 struct ctl_table_set *set,
191 const struct ctl_path *path, struct ctl_table *table);
192struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table);
193struct ctl_table_header *register_sysctl_table(struct ctl_table * table);
194struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
195 struct ctl_table *table);
196
197void unregister_sysctl_table(struct ctl_table_header * table);
198
199extern int sysctl_init(void);
200void do_sysctl_args(void);
201
202extern int pwrsw_enabled;
203extern int unaligned_enabled;
204extern int unaligned_dump_stack;
205extern int no_unaligned_warning;
206
207extern struct ctl_table sysctl_mount_point[];
208extern struct ctl_table random_table[];
209extern struct ctl_table firmware_config_table[];
210extern struct ctl_table epoll_table[];
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
239static inline void do_sysctl_args(void)
240{
241}
242#endif /* CONFIG_SYSCTL */
243
244int sysctl_max_threads(struct ctl_table *table, int write, void *buffer,
245 size_t *lenp, loff_t *ppos);
246
247#endif /* _LINUX_SYSCTL_H */