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_TWO ((void *)&sysctl_vals[2])
44#define SYSCTL_THREE ((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#define SYSCTL_NEG_ONE ((void *)&sysctl_vals[11])
55
56extern const int sysctl_vals[];
57
58#define SYSCTL_LONG_ZERO ((void *)&sysctl_long_vals[0])
59#define SYSCTL_LONG_ONE ((void *)&sysctl_long_vals[1])
60#define SYSCTL_LONG_MAX ((void *)&sysctl_long_vals[2])
61
62extern const unsigned long sysctl_long_vals[];
63
64typedef int proc_handler(const struct ctl_table *ctl, int write, void *buffer,
65 size_t *lenp, loff_t *ppos);
66
67int proc_dostring(const struct ctl_table *, int, void *, size_t *, loff_t *);
68int proc_dobool(const struct ctl_table *table, int write, void *buffer,
69 size_t *lenp, loff_t *ppos);
70int proc_dointvec(const struct ctl_table *, int, void *, size_t *, loff_t *);
71int proc_douintvec(const struct ctl_table *, int, void *, size_t *, loff_t *);
72int proc_dointvec_minmax(const struct ctl_table *, int, void *, size_t *, loff_t *);
73int proc_douintvec_minmax(const struct ctl_table *table, int write, void *buffer,
74 size_t *lenp, loff_t *ppos);
75int proc_dou8vec_minmax(const struct ctl_table *table, int write, void *buffer,
76 size_t *lenp, loff_t *ppos);
77int proc_dointvec_jiffies(const struct ctl_table *, int, void *, size_t *, loff_t *);
78int proc_dointvec_ms_jiffies_minmax(const struct ctl_table *table, int write,
79 void *buffer, size_t *lenp, loff_t *ppos);
80int proc_dointvec_userhz_jiffies(const struct ctl_table *, int, void *, size_t *,
81 loff_t *);
82int proc_dointvec_ms_jiffies(const struct ctl_table *, int, void *, size_t *,
83 loff_t *);
84int proc_doulongvec_minmax(const struct ctl_table *, int, void *, size_t *, loff_t *);
85int proc_doulongvec_ms_jiffies_minmax(const struct ctl_table *table, int, void *,
86 size_t *, loff_t *);
87int proc_do_large_bitmap(const struct ctl_table *, int, void *, size_t *, loff_t *);
88int proc_do_static_key(const struct ctl_table *table, int write, void *buffer,
89 size_t *lenp, loff_t *ppos);
90
91/*
92 * Register a set of sysctl names by calling register_sysctl
93 * with an initialised array of struct ctl_table's.
94 *
95 * sysctl names can be mirrored automatically under /proc/sys. The
96 * procname supplied controls /proc naming.
97 *
98 * The table's mode will be honoured for proc-fs access.
99 *
100 * Leaf nodes in the sysctl tree will be represented by a single file
101 * under /proc; non-leaf nodes will be represented by directories. A
102 * null procname disables /proc mirroring at this node.
103 *
104 * The data and maxlen fields of the ctl_table
105 * struct enable minimal validation of the values being written to be
106 * performed, and the mode field allows minimal authentication.
107 *
108 * There must be a proc_handler routine for any terminal nodes
109 * mirrored under /proc/sys (non-terminals are handled by a built-in
110 * directory handler). Several default handlers are available to
111 * cover common cases.
112 */
113
114/* Support for userspace poll() to watch for changes */
115struct ctl_table_poll {
116 atomic_t event;
117 wait_queue_head_t wait;
118};
119
120static inline void *proc_sys_poll_event(struct ctl_table_poll *poll)
121{
122 return (void *)(unsigned long)atomic_read(v: &poll->event);
123}
124
125#define __CTL_TABLE_POLL_INITIALIZER(name) { \
126 .event = ATOMIC_INIT(0), \
127 .wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.wait) }
128
129#define DEFINE_CTL_TABLE_POLL(name) \
130 struct ctl_table_poll name = __CTL_TABLE_POLL_INITIALIZER(name)
131
132/* A sysctl table is an array of struct ctl_table: */
133struct ctl_table {
134 const char *procname; /* Text ID for /proc/sys */
135 void *data;
136 int maxlen;
137 umode_t mode;
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/**
150 * struct ctl_table_header - maintains dynamic lists of struct ctl_table trees
151 * @ctl_table: pointer to the first element in ctl_table array
152 * @ctl_table_size: number of elements pointed by @ctl_table
153 * @used: The entry will never be touched when equal to 0.
154 * @count: Upped every time something is added to @inodes and downed every time
155 * something is removed from inodes
156 * @nreg: When nreg drops to 0 the ctl_table_header will be unregistered.
157 * @rcu: Delays the freeing of the inode. Introduced with "unfuck proc_sysctl ->d_compare()"
158 *
159 */
160struct ctl_table_header {
161 union {
162 struct {
163 const struct ctl_table *ctl_table;
164 int ctl_table_size;
165 int used;
166 int count;
167 int nreg;
168 };
169 struct rcu_head rcu;
170 };
171 struct completion *unregistering;
172 const struct ctl_table *ctl_table_arg;
173 struct ctl_table_root *root;
174 struct ctl_table_set *set;
175 struct ctl_dir *parent;
176 struct ctl_node *node;
177 struct hlist_head inodes; /* head for proc_inode->sysctl_inodes */
178 /**
179 * enum type - Enumeration to differentiate between ctl target types
180 * @SYSCTL_TABLE_TYPE_DEFAULT: ctl target with no special considerations
181 * @SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY: Used to identify a permanently
182 * empty directory target to serve
183 * as mount point.
184 */
185 enum {
186 SYSCTL_TABLE_TYPE_DEFAULT,
187 SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY,
188 } type;
189};
190
191struct ctl_dir {
192 /* Header must be at the start of ctl_dir */
193 struct ctl_table_header header;
194 struct rb_root root;
195};
196
197struct ctl_table_set {
198 int (*is_seen)(struct ctl_table_set *);
199 struct ctl_dir dir;
200};
201
202struct ctl_table_root {
203 struct ctl_table_set default_set;
204 struct ctl_table_set *(*lookup)(struct ctl_table_root *root);
205 void (*set_ownership)(struct ctl_table_header *head,
206 kuid_t *uid, kgid_t *gid);
207 int (*permissions)(struct ctl_table_header *head, const struct ctl_table *table);
208};
209
210#define register_sysctl(path, table) \
211 register_sysctl_sz(path, table, ARRAY_SIZE(table))
212
213#ifdef CONFIG_SYSCTL
214
215void proc_sys_poll_notify(struct ctl_table_poll *poll);
216
217extern void setup_sysctl_set(struct ctl_table_set *p,
218 struct ctl_table_root *root,
219 int (*is_seen)(struct ctl_table_set *));
220extern void retire_sysctl_set(struct ctl_table_set *set);
221
222struct ctl_table_header *__register_sysctl_table(
223 struct ctl_table_set *set,
224 const char *path, const struct ctl_table *table, size_t table_size);
225struct ctl_table_header *register_sysctl_sz(const char *path, const struct ctl_table *table,
226 size_t table_size);
227void unregister_sysctl_table(struct ctl_table_header * table);
228
229extern int sysctl_init_bases(void);
230extern void __register_sysctl_init(const char *path, const struct ctl_table *table,
231 const char *table_name, size_t table_size);
232#define register_sysctl_init(path, table) \
233 __register_sysctl_init(path, table, #table, ARRAY_SIZE(table))
234extern struct ctl_table_header *register_sysctl_mount_point(const char *path);
235
236void do_sysctl_args(void);
237bool sysctl_is_alias(char *param);
238int do_proc_douintvec(const 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
250#else /* CONFIG_SYSCTL */
251
252static inline void register_sysctl_init(const char *path, const struct ctl_table *table)
253{
254}
255
256static inline struct ctl_table_header *register_sysctl_mount_point(const char *path)
257{
258 return NULL;
259}
260
261static inline struct ctl_table_header *register_sysctl_sz(const char *path,
262 const struct ctl_table *table,
263 size_t table_size)
264{
265 return NULL;
266}
267
268static inline void unregister_sysctl_table(struct ctl_table_header * table)
269{
270}
271
272static inline void setup_sysctl_set(struct ctl_table_set *p,
273 struct ctl_table_root *root,
274 int (*is_seen)(struct ctl_table_set *))
275{
276}
277
278static inline void do_sysctl_args(void)
279{
280}
281
282static inline bool sysctl_is_alias(char *param)
283{
284 return false;
285}
286#endif /* CONFIG_SYSCTL */
287
288int sysctl_max_threads(const struct ctl_table *table, int write, void *buffer,
289 size_t *lenp, loff_t *ppos);
290
291#endif /* _LINUX_SYSCTL_H */
292

source code of linux/include/linux/sysctl.h

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