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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_dointvec_jiffies(struct ctl_table *, int, void *, size_t *, loff_t *);
57int proc_dointvec_userhz_jiffies(struct ctl_table *, int, void *, size_t *,
58 loff_t *);
59int proc_dointvec_ms_jiffies(struct ctl_table *, int, void *, size_t *,
60 loff_t *);
61int proc_doulongvec_minmax(struct ctl_table *, int, void *, size_t *, loff_t *);
62int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int, void *,
63 size_t *, loff_t *);
64int proc_do_large_bitmap(struct ctl_table *, int, void *, size_t *, loff_t *);
65int proc_do_static_key(struct ctl_table *table, int write, void *buffer,
66 size_t *lenp, loff_t *ppos);
67
68/*
69 * Register a set of sysctl names by calling register_sysctl_table
70 * with an initialised array of struct ctl_table's. An entry with
71 * NULL procname terminates the table. table->de will be
72 * set up by the registration and need not be initialised in advance.
73 *
74 * sysctl names can be mirrored automatically under /proc/sys. The
75 * procname supplied controls /proc naming.
76 *
77 * The table's mode will be honoured for proc-fs access.
78 *
79 * Leaf nodes in the sysctl tree will be represented by a single file
80 * under /proc; non-leaf nodes will be represented by directories. A
81 * null procname disables /proc mirroring at this node.
82 *
83 * The data and maxlen fields of the ctl_table
84 * struct enable minimal validation of the values being written to be
85 * performed, and the mode field allows minimal authentication.
86 *
87 * There must be a proc_handler routine for any terminal nodes
88 * mirrored under /proc/sys (non-terminals are handled by a built-in
89 * directory handler). Several default handlers are available to
90 * cover common cases.
91 */
92
93/* Support for userspace poll() to watch for changes */
94struct ctl_table_poll {
95 atomic_t event;
96 wait_queue_head_t wait;
97};
98
99static inline void *proc_sys_poll_event(struct ctl_table_poll *poll)
100{
101 return (void *)(unsigned long)atomic_read(&poll->event);
102}
103
104#define __CTL_TABLE_POLL_INITIALIZER(name) { \
105 .event = ATOMIC_INIT(0), \
106 .wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.wait) }
107
108#define DEFINE_CTL_TABLE_POLL(name) \
109 struct ctl_table_poll name = __CTL_TABLE_POLL_INITIALIZER(name)
110
111/* A sysctl table is an array of struct ctl_table: */
112struct ctl_table {
113 const char *procname; /* Text ID for /proc/sys, or zero */
114 void *data;
115 int maxlen;
116 umode_t mode;
117 struct ctl_table *child; /* Deprecated */
118 proc_handler *proc_handler; /* Callback for text formatting */
119 struct ctl_table_poll *poll;
120 void *extra1;
121 void *extra2;
122} __randomize_layout;
123
124struct ctl_node {
125 struct rb_node node;
126 struct ctl_table_header *header;
127};
128
129/* struct ctl_table_header is used to maintain dynamic lists of
130 struct ctl_table trees. */
131struct ctl_table_header {
132 union {
133 struct {
134 struct ctl_table *ctl_table;
135 int used;
136 int count;
137 int nreg;
138 };
139 struct rcu_head rcu;
140 };
141 struct completion *unregistering;
142 struct ctl_table *ctl_table_arg;
143 struct ctl_table_root *root;
144 struct ctl_table_set *set;
145 struct ctl_dir *parent;
146 struct ctl_node *node;
147 struct hlist_head inodes; /* head for proc_inode->sysctl_inodes */
148};
149
150struct ctl_dir {
151 /* Header must be at the start of ctl_dir */
152 struct ctl_table_header header;
153 struct rb_root root;
154};
155
156struct ctl_table_set {
157 int (*is_seen)(struct ctl_table_set *);
158 struct ctl_dir dir;
159};
160
161struct ctl_table_root {
162 struct ctl_table_set default_set;
163 struct ctl_table_set *(*lookup)(struct ctl_table_root *root);
164 void (*set_ownership)(struct ctl_table_header *head,
165 struct ctl_table *table,
166 kuid_t *uid, kgid_t *gid);
167 int (*permissions)(struct ctl_table_header *head, struct ctl_table *table);
168};
169
170/* struct ctl_path describes where in the hierarchy a table is added */
171struct ctl_path {
172 const char *procname;
173};
174
175#ifdef CONFIG_SYSCTL
176
177void proc_sys_poll_notify(struct ctl_table_poll *poll);
178
179extern void setup_sysctl_set(struct ctl_table_set *p,
180 struct ctl_table_root *root,
181 int (*is_seen)(struct ctl_table_set *));
182extern void retire_sysctl_set(struct ctl_table_set *set);
183
184struct ctl_table_header *__register_sysctl_table(
185 struct ctl_table_set *set,
186 const char *path, struct ctl_table *table);
187struct ctl_table_header *__register_sysctl_paths(
188 struct ctl_table_set *set,
189 const struct ctl_path *path, struct ctl_table *table);
190struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table);
191struct ctl_table_header *register_sysctl_table(struct ctl_table * table);
192struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
193 struct ctl_table *table);
194
195void unregister_sysctl_table(struct ctl_table_header * table);
196
197extern int sysctl_init(void);
198void do_sysctl_args(void);
199
200extern int pwrsw_enabled;
201extern int unaligned_enabled;
202extern int unaligned_dump_stack;
203extern int no_unaligned_warning;
204
205extern struct ctl_table sysctl_mount_point[];
206extern struct ctl_table random_table[];
207extern struct ctl_table firmware_config_table[];
208extern struct ctl_table epoll_table[];
209
210#else /* CONFIG_SYSCTL */
211static inline struct ctl_table_header *register_sysctl_table(struct ctl_table * table)
212{
213 return NULL;
214}
215
216static inline struct ctl_table_header *register_sysctl_paths(
217 const struct ctl_path *path, struct ctl_table *table)
218{
219 return NULL;
220}
221
222static inline struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table)
223{
224 return NULL;
225}
226
227static inline void unregister_sysctl_table(struct ctl_table_header * table)
228{
229}
230
231static inline void setup_sysctl_set(struct ctl_table_set *p,
232 struct ctl_table_root *root,
233 int (*is_seen)(struct ctl_table_set *))
234{
235}
236
237static inline void do_sysctl_args(void)
238{
239}
240#endif /* CONFIG_SYSCTL */
241
242int sysctl_max_threads(struct ctl_table *table, int write, void *buffer,
243 size_t *lenp, loff_t *ppos);
244
245#endif /* _LINUX_SYSCTL_H */