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_userhz_jiffies(struct ctl_table *, int, void *, size_t *,
79 loff_t *);
80 int proc_dointvec_ms_jiffies(struct ctl_table *, int, void *, size_t *,
81 loff_t *);
82 int proc_doulongvec_minmax(struct ctl_table *, int, void *, size_t *, loff_t *);
83 int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int, void *,
84 size_t *, loff_t *);
85 int proc_do_large_bitmap(struct ctl_table *, int, void *, size_t *, loff_t *);
86 int proc_do_static_key(struct ctl_table *table, int write, void *buffer,
87 size_t *lenp, loff_t *ppos);
88
89 /*
90 * Register a set of sysctl names by calling register_sysctl_table
91 * with an initialised array of struct ctl_table's. An entry with
92 * NULL procname terminates the table. table->de will be
93 * set up by the registration and need not be initialised in advance.
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 */
115 struct ctl_table_poll {
116 atomic_t event;
117 wait_queue_head_t wait;
118 };
119
proc_sys_poll_event(struct ctl_table_poll * poll)120 static inline void *proc_sys_poll_event(struct ctl_table_poll *poll)
121 {
122 return (void *)(unsigned long)atomic_read(&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: */
133 struct ctl_table {
134 const char *procname; /* Text ID for /proc/sys, or zero */
135 void *data;
136 int maxlen;
137 umode_t mode;
138 struct ctl_table *child; /* Deprecated */
139 proc_handler *proc_handler; /* Callback for text formatting */
140 struct ctl_table_poll *poll;
141 void *extra1;
142 void *extra2;
143 } __randomize_layout;
144
145 struct ctl_node {
146 struct rb_node node;
147 struct ctl_table_header *header;
148 };
149
150 /* struct ctl_table_header is used to maintain dynamic lists of
151 struct ctl_table trees. */
152 struct ctl_table_header {
153 union {
154 struct {
155 struct ctl_table *ctl_table;
156 int used;
157 int count;
158 int nreg;
159 };
160 struct rcu_head rcu;
161 };
162 struct completion *unregistering;
163 struct ctl_table *ctl_table_arg;
164 struct ctl_table_root *root;
165 struct ctl_table_set *set;
166 struct ctl_dir *parent;
167 struct ctl_node *node;
168 struct hlist_head inodes; /* head for proc_inode->sysctl_inodes */
169 };
170
171 struct ctl_dir {
172 /* Header must be at the start of ctl_dir */
173 struct ctl_table_header header;
174 struct rb_root root;
175 };
176
177 struct ctl_table_set {
178 int (*is_seen)(struct ctl_table_set *);
179 struct ctl_dir dir;
180 };
181
182 struct ctl_table_root {
183 struct ctl_table_set default_set;
184 struct ctl_table_set *(*lookup)(struct ctl_table_root *root);
185 void (*set_ownership)(struct ctl_table_header *head,
186 struct ctl_table *table,
187 kuid_t *uid, kgid_t *gid);
188 int (*permissions)(struct ctl_table_header *head, struct ctl_table *table);
189 };
190
191 /* struct ctl_path describes where in the hierarchy a table is added */
192 struct ctl_path {
193 const char *procname;
194 };
195
196 #ifdef CONFIG_SYSCTL
197
198 #define DECLARE_SYSCTL_BASE(_name, _table) \
199 static struct ctl_table _name##_base_table[] = { \
200 { \
201 .procname = #_name, \
202 .mode = 0555, \
203 .child = _table, \
204 }, \
205 { }, \
206 }
207
208 extern int __register_sysctl_base(struct ctl_table *base_table);
209
210 #define register_sysctl_base(_name) __register_sysctl_base(_name##_base_table)
211
212 void proc_sys_poll_notify(struct ctl_table_poll *poll);
213
214 extern void setup_sysctl_set(struct ctl_table_set *p,
215 struct ctl_table_root *root,
216 int (*is_seen)(struct ctl_table_set *));
217 extern void retire_sysctl_set(struct ctl_table_set *set);
218
219 struct ctl_table_header *__register_sysctl_table(
220 struct ctl_table_set *set,
221 const char *path, struct ctl_table *table);
222 struct ctl_table_header *__register_sysctl_paths(
223 struct ctl_table_set *set,
224 const struct ctl_path *path, struct ctl_table *table);
225 struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table);
226 struct ctl_table_header *register_sysctl_table(struct ctl_table * table);
227 struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
228 struct ctl_table *table);
229
230 void unregister_sysctl_table(struct ctl_table_header * table);
231
232 extern int sysctl_init_bases(void);
233 extern void __register_sysctl_init(const char *path, struct ctl_table *table,
234 const char *table_name);
235 #define register_sysctl_init(path, table) __register_sysctl_init(path, table, #table)
236 extern struct ctl_table_header *register_sysctl_mount_point(const char *path);
237
238 void do_sysctl_args(void);
239 int do_proc_douintvec(struct ctl_table *table, int write,
240 void *buffer, size_t *lenp, loff_t *ppos,
241 int (*conv)(unsigned long *lvalp,
242 unsigned int *valp,
243 int write, void *data),
244 void *data);
245
246 extern int pwrsw_enabled;
247 extern int unaligned_enabled;
248 extern int unaligned_dump_stack;
249 extern int no_unaligned_warning;
250
251 extern struct ctl_table sysctl_mount_point[];
252
253 #else /* CONFIG_SYSCTL */
254
255 #define DECLARE_SYSCTL_BASE(_name, _table)
256
__register_sysctl_base(struct ctl_table * base_table)257 static inline int __register_sysctl_base(struct ctl_table *base_table)
258 {
259 return 0;
260 }
261
262 #define register_sysctl_base(table) __register_sysctl_base(table)
263
register_sysctl_table(struct ctl_table * table)264 static inline struct ctl_table_header *register_sysctl_table(struct ctl_table * table)
265 {
266 return NULL;
267 }
268
register_sysctl_mount_point(const char * path)269 static inline struct ctl_table_header *register_sysctl_mount_point(const char *path)
270 {
271 return NULL;
272 }
273
register_sysctl_paths(const struct ctl_path * path,struct ctl_table * table)274 static inline struct ctl_table_header *register_sysctl_paths(
275 const struct ctl_path *path, struct ctl_table *table)
276 {
277 return NULL;
278 }
279
register_sysctl(const char * path,struct ctl_table * table)280 static inline struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table)
281 {
282 return NULL;
283 }
284
unregister_sysctl_table(struct ctl_table_header * table)285 static inline void unregister_sysctl_table(struct ctl_table_header * table)
286 {
287 }
288
setup_sysctl_set(struct ctl_table_set * p,struct ctl_table_root * root,int (* is_seen)(struct ctl_table_set *))289 static inline void setup_sysctl_set(struct ctl_table_set *p,
290 struct ctl_table_root *root,
291 int (*is_seen)(struct ctl_table_set *))
292 {
293 }
294
do_sysctl_args(void)295 static inline void do_sysctl_args(void)
296 {
297 }
298 #endif /* CONFIG_SYSCTL */
299
300 int sysctl_max_threads(struct ctl_table *table, int write, void *buffer,
301 size_t *lenp, loff_t *ppos);
302
303 #endif /* _LINUX_SYSCTL_H */
304