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