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_NEG_ONE			((void *)&sysctl_vals[0])
42#define SYSCTL_ZERO			((void *)&sysctl_vals[1])
43#define SYSCTL_ONE			((void *)&sysctl_vals[2])
44#define SYSCTL_TWO			((void *)&sysctl_vals[3])
45#define SYSCTL_FOUR			((void *)&sysctl_vals[4])
46#define SYSCTL_ONE_HUNDRED		((void *)&sysctl_vals[5])
47#define SYSCTL_TWO_HUNDRED		((void *)&sysctl_vals[6])
48#define SYSCTL_ONE_THOUSAND		((void *)&sysctl_vals[7])
49#define SYSCTL_THREE_THOUSAND		((void *)&sysctl_vals[8])
50#define SYSCTL_INT_MAX			((void *)&sysctl_vals[9])
51
52/* this is needed for the proc_dointvec_minmax for [fs_]overflow UID and GID */
53#define SYSCTL_MAXOLDUID		((void *)&sysctl_vals[10])
54
55extern const int sysctl_vals[];
56
57#define SYSCTL_LONG_ZERO	((void *)&sysctl_long_vals[0])
58#define SYSCTL_LONG_ONE		((void *)&sysctl_long_vals[1])
59#define SYSCTL_LONG_MAX		((void *)&sysctl_long_vals[2])
60
61extern const unsigned long sysctl_long_vals[];
62
63typedef int proc_handler(struct ctl_table *ctl, int write, void *buffer,
64		size_t *lenp, loff_t *ppos);
65
66int proc_dostring(struct ctl_table *, int, void *, size_t *, loff_t *);
67int proc_dobool(struct ctl_table *table, int write, void *buffer,
68		size_t *lenp, loff_t *ppos);
69int proc_dointvec(struct ctl_table *, int, void *, size_t *, loff_t *);
70int proc_douintvec(struct ctl_table *, int, void *, size_t *, loff_t *);
71int proc_dointvec_minmax(struct ctl_table *, int, void *, size_t *, loff_t *);
72int proc_douintvec_minmax(struct ctl_table *table, int write, void *buffer,
73		size_t *lenp, loff_t *ppos);
74int proc_dou8vec_minmax(struct ctl_table *table, int write, void *buffer,
75			size_t *lenp, loff_t *ppos);
76int proc_dointvec_jiffies(struct ctl_table *, int, void *, size_t *, loff_t *);
77int proc_dointvec_userhz_jiffies(struct ctl_table *, int, void *, size_t *,
78		loff_t *);
79int proc_dointvec_ms_jiffies(struct ctl_table *, int, void *, size_t *,
80		loff_t *);
81int proc_doulongvec_minmax(struct ctl_table *, int, void *, size_t *, loff_t *);
82int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int, void *,
83		size_t *, loff_t *);
84int proc_do_large_bitmap(struct ctl_table *, int, void *, size_t *, loff_t *);
85int proc_do_static_key(struct ctl_table *table, int write, void *buffer,
86		size_t *lenp, loff_t *ppos);
87
88/*
89 * Register a set of sysctl names by calling register_sysctl_table
90 * with an initialised array of struct ctl_table's.  An entry with
91 * NULL procname terminates the table.  table->de will be
92 * set up by the registration and need not be initialised in advance.
93 *
94 * sysctl names can be mirrored automatically under /proc/sys.  The
95 * procname supplied controls /proc naming.
96 *
97 * The table's mode will be honoured for proc-fs access.
98 *
99 * Leaf nodes in the sysctl tree will be represented by a single file
100 * under /proc; non-leaf nodes will be represented by directories.  A
101 * null procname disables /proc mirroring at this node.
102 *
103 * The data and maxlen fields of the ctl_table
104 * struct enable minimal validation of the values being written to be
105 * performed, and the mode field allows minimal authentication.
106 *
107 * There must be a proc_handler routine for any terminal nodes
108 * mirrored under /proc/sys (non-terminals are handled by a built-in
109 * directory handler).  Several default handlers are available to
110 * cover common cases.
111 */
112
113/* Support for userspace poll() to watch for changes */
114struct ctl_table_poll {
115	atomic_t event;
116	wait_queue_head_t wait;
117};
118
119static inline void *proc_sys_poll_event(struct ctl_table_poll *poll)
120{
121	return (void *)(unsigned long)atomic_read(&poll->event);
122}
123
124#define __CTL_TABLE_POLL_INITIALIZER(name) {				\
125	.event = ATOMIC_INIT(0),					\
126	.wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.wait) }
127
128#define DEFINE_CTL_TABLE_POLL(name)					\
129	struct ctl_table_poll name = __CTL_TABLE_POLL_INITIALIZER(name)
130
131/* A sysctl table is an array of struct ctl_table: */
132struct ctl_table {
133	const char *procname;		/* Text ID for /proc/sys, or zero */
134	void *data;
135	int maxlen;
136	umode_t mode;
137	struct ctl_table *child;	/* Deprecated */
138	proc_handler *proc_handler;	/* Callback for text formatting */
139	struct ctl_table_poll *poll;
140	void *extra1;
141	void *extra2;
142} __randomize_layout;
143
144struct ctl_node {
145	struct rb_node node;
146	struct ctl_table_header *header;
147};
148
149/* struct ctl_table_header is used to maintain dynamic lists of
150   struct ctl_table trees. */
151struct ctl_table_header {
152	union {
153		struct {
154			struct ctl_table *ctl_table;
155			int used;
156			int count;
157			int nreg;
158		};
159		struct rcu_head rcu;
160	};
161	struct completion *unregistering;
162	struct ctl_table *ctl_table_arg;
163	struct ctl_table_root *root;
164	struct ctl_table_set *set;
165	struct ctl_dir *parent;
166	struct ctl_node *node;
167	struct hlist_head inodes; /* head for proc_inode->sysctl_inodes */
168};
169
170struct ctl_dir {
171	/* Header must be at the start of ctl_dir */
172	struct ctl_table_header header;
173	struct rb_root root;
174};
175
176struct ctl_table_set {
177	int (*is_seen)(struct ctl_table_set *);
178	struct ctl_dir dir;
179};
180
181struct ctl_table_root {
182	struct ctl_table_set default_set;
183	struct ctl_table_set *(*lookup)(struct ctl_table_root *root);
184	void (*set_ownership)(struct ctl_table_header *head,
185			      struct ctl_table *table,
186			      kuid_t *uid, kgid_t *gid);
187	int (*permissions)(struct ctl_table_header *head, struct ctl_table *table);
188};
189
190/* struct ctl_path describes where in the hierarchy a table is added */
191struct ctl_path {
192	const char *procname;
193};
194
195#ifdef CONFIG_SYSCTL
196
197#define DECLARE_SYSCTL_BASE(_name, _table)				\
198static struct ctl_table _name##_base_table[] = {			\
199	{								\
200		.procname	= #_name,				\
201		.mode		= 0555,					\
202		.child		= _table,				\
203	},								\
204	{ },								\
205}
206
207extern int __register_sysctl_base(struct ctl_table *base_table);
208
209#define register_sysctl_base(_name) __register_sysctl_base(_name##_base_table)
210
211void proc_sys_poll_notify(struct ctl_table_poll *poll);
212
213extern void setup_sysctl_set(struct ctl_table_set *p,
214	struct ctl_table_root *root,
215	int (*is_seen)(struct ctl_table_set *));
216extern void retire_sysctl_set(struct ctl_table_set *set);
217
218struct ctl_table_header *__register_sysctl_table(
219	struct ctl_table_set *set,
220	const char *path, struct ctl_table *table);
221struct ctl_table_header *__register_sysctl_paths(
222	struct ctl_table_set *set,
223	const struct ctl_path *path, struct ctl_table *table);
224struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table);
225struct ctl_table_header *register_sysctl_table(struct ctl_table * table);
226struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
227						struct ctl_table *table);
228
229void unregister_sysctl_table(struct ctl_table_header * table);
230
231extern int sysctl_init_bases(void);
232extern void __register_sysctl_init(const char *path, struct ctl_table *table,
233				 const char *table_name);
234#define register_sysctl_init(path, table) __register_sysctl_init(path, table, #table)
235extern struct ctl_table_header *register_sysctl_mount_point(const char *path);
236
237void do_sysctl_args(void);
238int do_proc_douintvec(struct ctl_table *table, int write,
239		      void *buffer, size_t *lenp, loff_t *ppos,
240		      int (*conv)(unsigned long *lvalp,
241				  unsigned int *valp,
242				  int write, void *data),
243		      void *data);
244
245extern int pwrsw_enabled;
246extern int unaligned_enabled;
247extern int unaligned_dump_stack;
248extern int no_unaligned_warning;
249
250extern struct ctl_table sysctl_mount_point[];
251
252#else /* CONFIG_SYSCTL */
253
254#define DECLARE_SYSCTL_BASE(_name, _table)
255
256static inline int __register_sysctl_base(struct ctl_table *base_table)
257{
258	return 0;
259}
260
261#define register_sysctl_base(table) __register_sysctl_base(table)
262
263static inline struct ctl_table_header *register_sysctl_table(struct ctl_table * table)
264{
265	return NULL;
266}
267
268static inline struct sysctl_header *register_sysctl_mount_point(const char *path)
269{
270	return NULL;
271}
272
273static inline struct ctl_table_header *register_sysctl_paths(
274			const struct ctl_path *path, struct ctl_table *table)
275{
276	return NULL;
277}
278
279static inline struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table)
280{
281	return NULL;
282}
283
284static inline void unregister_sysctl_table(struct ctl_table_header * table)
285{
286}
287
288static inline void setup_sysctl_set(struct ctl_table_set *p,
289	struct ctl_table_root *root,
290	int (*is_seen)(struct ctl_table_set *))
291{
292}
293
294static inline void do_sysctl_args(void)
295{
296}
297#endif /* CONFIG_SYSCTL */
298
299int sysctl_max_threads(struct ctl_table *table, int write, void *buffer,
300		size_t *lenp, loff_t *ppos);
301
302#endif /* _LINUX_SYSCTL_H */
303