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