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 */
33 struct completion;
34 struct ctl_table;
35 struct nsproxy;
36 struct ctl_table_root;
37 struct ctl_table_header;
38 struct 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
56 extern 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
62 extern const unsigned long sysctl_long_vals[];
63
64 typedef int proc_handler(struct ctl_table *ctl, int write, void *buffer,
65 size_t *lenp, loff_t *ppos);
66
67 int proc_dostring(struct ctl_table *, int, void *, size_t *, loff_t *);
68 int proc_dobool(struct ctl_table *table, int write, void *buffer,
69 size_t *lenp, loff_t *ppos);
70 int proc_dointvec(struct ctl_table *, int, void *, size_t *, loff_t *);
71 int proc_douintvec(struct ctl_table *, int, void *, size_t *, loff_t *);
72 int proc_dointvec_minmax(struct ctl_table *, int, void *, size_t *, loff_t *);
73 int proc_douintvec_minmax(struct ctl_table *table, int write, void *buffer,
74 size_t *lenp, loff_t *ppos);
75 int proc_dou8vec_minmax(struct ctl_table *table, int write, void *buffer,
76 size_t *lenp, loff_t *ppos);
77 int proc_dointvec_jiffies(struct ctl_table *, int, void *, size_t *, loff_t *);
78 int proc_dointvec_ms_jiffies_minmax(struct ctl_table *table, int write,
79 void *buffer, size_t *lenp, loff_t *ppos);
80 int proc_dointvec_userhz_jiffies(struct ctl_table *, int, void *, size_t *,
81 loff_t *);
82 int proc_dointvec_ms_jiffies(struct ctl_table *, int, void *, size_t *,
83 loff_t *);
84 int proc_doulongvec_minmax(struct ctl_table *, int, void *, size_t *, loff_t *);
85 int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int, void *,
86 size_t *, loff_t *);
87 int proc_do_large_bitmap(struct ctl_table *, int, void *, size_t *, loff_t *);
88 int proc_do_static_key(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_table
93 * with an initialised array of struct ctl_table's. An entry with
94 * NULL procname terminates the table. table->de will be
95 * set up by the registration and need not be initialised in advance.
96 *
97 * sysctl names can be mirrored automatically under /proc/sys. The
98 * procname supplied controls /proc naming.
99 *
100 * The table's mode will be honoured for proc-fs access.
101 *
102 * Leaf nodes in the sysctl tree will be represented by a single file
103 * under /proc; non-leaf nodes will be represented by directories. A
104 * null procname disables /proc mirroring at this node.
105 *
106 * The data and maxlen fields of the ctl_table
107 * struct enable minimal validation of the values being written to be
108 * performed, and the mode field allows minimal authentication.
109 *
110 * There must be a proc_handler routine for any terminal nodes
111 * mirrored under /proc/sys (non-terminals are handled by a built-in
112 * directory handler). Several default handlers are available to
113 * cover common cases.
114 */
115
116 /* Support for userspace poll() to watch for changes */
117 struct ctl_table_poll {
118 atomic_t event;
119 wait_queue_head_t wait;
120 };
121
proc_sys_poll_event(struct ctl_table_poll * poll)122 static inline void *proc_sys_poll_event(struct ctl_table_poll *poll)
123 {
124 return (void *)(unsigned long)atomic_read(&poll->event);
125 }
126
127 #define __CTL_TABLE_POLL_INITIALIZER(name) { \
128 .event = ATOMIC_INIT(0), \
129 .wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.wait) }
130
131 #define DEFINE_CTL_TABLE_POLL(name) \
132 struct ctl_table_poll name = __CTL_TABLE_POLL_INITIALIZER(name)
133
134 /* A sysctl table is an array of struct ctl_table: */
135 struct ctl_table {
136 const char *procname; /* Text ID for /proc/sys, or zero */
137 void *data;
138 int maxlen;
139 umode_t mode;
140 struct ctl_table *child; /* Deprecated */
141 proc_handler *proc_handler; /* Callback for text formatting */
142 struct ctl_table_poll *poll;
143 void *extra1;
144 void *extra2;
145 } __randomize_layout;
146
147 struct ctl_node {
148 struct rb_node node;
149 struct ctl_table_header *header;
150 };
151
152 /* struct ctl_table_header is used to maintain dynamic lists of
153 struct ctl_table trees. */
154 struct ctl_table_header {
155 union {
156 struct {
157 struct ctl_table *ctl_table;
158 int used;
159 int count;
160 int nreg;
161 };
162 struct rcu_head rcu;
163 };
164 struct completion *unregistering;
165 struct ctl_table *ctl_table_arg;
166 struct ctl_table_root *root;
167 struct ctl_table_set *set;
168 struct ctl_dir *parent;
169 struct ctl_node *node;
170 struct hlist_head inodes; /* head for proc_inode->sysctl_inodes */
171 };
172
173 struct ctl_dir {
174 /* Header must be at the start of ctl_dir */
175 struct ctl_table_header header;
176 struct rb_root root;
177 };
178
179 struct ctl_table_set {
180 int (*is_seen)(struct ctl_table_set *);
181 struct ctl_dir dir;
182 };
183
184 struct ctl_table_root {
185 struct ctl_table_set default_set;
186 struct ctl_table_set *(*lookup)(struct ctl_table_root *root);
187 void (*set_ownership)(struct ctl_table_header *head,
188 struct ctl_table *table,
189 kuid_t *uid, kgid_t *gid);
190 int (*permissions)(struct ctl_table_header *head, struct ctl_table *table);
191 };
192
193 /* struct ctl_path describes where in the hierarchy a table is added */
194 struct ctl_path {
195 const char *procname;
196 };
197
198 #ifdef CONFIG_SYSCTL
199
200 #define DECLARE_SYSCTL_BASE(_name, _table) \
201 static struct ctl_table _name##_base_table[] = { \
202 { \
203 .procname = #_name, \
204 .mode = 0555, \
205 .child = _table, \
206 }, \
207 { }, \
208 }
209
210 extern int __register_sysctl_base(struct ctl_table *base_table);
211
212 #define register_sysctl_base(_name) __register_sysctl_base(_name##_base_table)
213
214 void proc_sys_poll_notify(struct ctl_table_poll *poll);
215
216 extern void setup_sysctl_set(struct ctl_table_set *p,
217 struct ctl_table_root *root,
218 int (*is_seen)(struct ctl_table_set *));
219 extern void retire_sysctl_set(struct ctl_table_set *set);
220
221 struct ctl_table_header *__register_sysctl_table(
222 struct ctl_table_set *set,
223 const char *path, struct ctl_table *table);
224 struct ctl_table_header *__register_sysctl_paths(
225 struct ctl_table_set *set,
226 const struct ctl_path *path, struct ctl_table *table);
227 struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table);
228 struct ctl_table_header *register_sysctl_table(struct ctl_table * table);
229 struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
230 struct ctl_table *table);
231
232 void unregister_sysctl_table(struct ctl_table_header * table);
233
234 extern int sysctl_init_bases(void);
235 extern void __register_sysctl_init(const char *path, struct ctl_table *table,
236 const char *table_name);
237 #define register_sysctl_init(path, table) __register_sysctl_init(path, table, #table)
238 extern struct ctl_table_header *register_sysctl_mount_point(const char *path);
239
240 void do_sysctl_args(void);
241 int do_proc_douintvec(struct ctl_table *table, int write,
242 void *buffer, size_t *lenp, loff_t *ppos,
243 int (*conv)(unsigned long *lvalp,
244 unsigned int *valp,
245 int write, void *data),
246 void *data);
247
248 extern int pwrsw_enabled;
249 extern int unaligned_enabled;
250 extern int unaligned_dump_stack;
251 extern int no_unaligned_warning;
252
253 extern struct ctl_table sysctl_mount_point[];
254
255 #else /* CONFIG_SYSCTL */
256
257 #define DECLARE_SYSCTL_BASE(_name, _table)
258
__register_sysctl_base(struct ctl_table * base_table)259 static inline int __register_sysctl_base(struct ctl_table *base_table)
260 {
261 return 0;
262 }
263
264 #define register_sysctl_base(table) __register_sysctl_base(table)
265
register_sysctl_table(struct ctl_table * table)266 static inline struct ctl_table_header *register_sysctl_table(struct ctl_table * table)
267 {
268 return NULL;
269 }
270
register_sysctl_init(const char * path,struct ctl_table * table)271 static inline void register_sysctl_init(const char *path, struct ctl_table *table)
272 {
273 }
274
register_sysctl_mount_point(const char * path)275 static inline struct ctl_table_header *register_sysctl_mount_point(const char *path)
276 {
277 return NULL;
278 }
279
register_sysctl_paths(const struct ctl_path * path,struct ctl_table * table)280 static inline struct ctl_table_header *register_sysctl_paths(
281 const struct ctl_path *path, struct ctl_table *table)
282 {
283 return NULL;
284 }
285
register_sysctl(const char * path,struct ctl_table * table)286 static inline struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table)
287 {
288 return NULL;
289 }
290
unregister_sysctl_table(struct ctl_table_header * table)291 static inline void unregister_sysctl_table(struct ctl_table_header * table)
292 {
293 }
294
setup_sysctl_set(struct ctl_table_set * p,struct ctl_table_root * root,int (* is_seen)(struct ctl_table_set *))295 static inline void setup_sysctl_set(struct ctl_table_set *p,
296 struct ctl_table_root *root,
297 int (*is_seen)(struct ctl_table_set *))
298 {
299 }
300
do_sysctl_args(void)301 static inline void do_sysctl_args(void)
302 {
303 }
304 #endif /* CONFIG_SYSCTL */
305
306 int sysctl_max_threads(struct ctl_table *table, int write, void *buffer,
307 size_t *lenp, loff_t *ppos);
308
309 #endif /* _LINUX_SYSCTL_H */
310