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_INT_MAX ((void *)&sysctl_vals[2])
44
45 extern const int sysctl_vals[];
46
47 typedef int proc_handler(struct ctl_table *ctl, int write, void *buffer,
48 size_t *lenp, loff_t *ppos);
49
50 int proc_dostring(struct ctl_table *, int, void *, size_t *, loff_t *);
51 int proc_dobool(struct ctl_table *table, int write, void *buffer,
52 size_t *lenp, loff_t *ppos);
53 int proc_dointvec(struct ctl_table *, int, void *, size_t *, loff_t *);
54 int proc_douintvec(struct ctl_table *, int, void *, size_t *, loff_t *);
55 int proc_dointvec_minmax(struct ctl_table *, int, void *, size_t *, loff_t *);
56 int proc_douintvec_minmax(struct ctl_table *table, int write, void *buffer,
57 size_t *lenp, loff_t *ppos);
58 int proc_dou8vec_minmax(struct ctl_table *table, int write, void *buffer,
59 size_t *lenp, loff_t *ppos);
60 int proc_dointvec_jiffies(struct ctl_table *, int, void *, size_t *, loff_t *);
61 int proc_dointvec_userhz_jiffies(struct ctl_table *, int, void *, size_t *,
62 loff_t *);
63 int proc_dointvec_ms_jiffies(struct ctl_table *, int, void *, size_t *,
64 loff_t *);
65 int proc_doulongvec_minmax(struct ctl_table *, int, void *, size_t *, loff_t *);
66 int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int, void *,
67 size_t *, loff_t *);
68 int proc_do_large_bitmap(struct ctl_table *, int, void *, size_t *, loff_t *);
69 int proc_do_static_key(struct ctl_table *table, int write, void *buffer,
70 size_t *lenp, loff_t *ppos);
71
72 /*
73 * Register a set of sysctl names by calling register_sysctl_table
74 * with an initialised array of struct ctl_table's. An entry with
75 * NULL procname terminates the table. table->de will be
76 * set up by the registration and need not be initialised in advance.
77 *
78 * sysctl names can be mirrored automatically under /proc/sys. The
79 * procname supplied controls /proc naming.
80 *
81 * The table's mode will be honoured for proc-fs access.
82 *
83 * Leaf nodes in the sysctl tree will be represented by a single file
84 * under /proc; non-leaf nodes will be represented by directories. A
85 * null procname disables /proc mirroring at this node.
86 *
87 * The data and maxlen fields of the ctl_table
88 * struct enable minimal validation of the values being written to be
89 * performed, and the mode field allows minimal authentication.
90 *
91 * There must be a proc_handler routine for any terminal nodes
92 * mirrored under /proc/sys (non-terminals are handled by a built-in
93 * directory handler). Several default handlers are available to
94 * cover common cases.
95 */
96
97 /* Support for userspace poll() to watch for changes */
98 struct ctl_table_poll {
99 atomic_t event;
100 wait_queue_head_t wait;
101 };
102
proc_sys_poll_event(struct ctl_table_poll * poll)103 static inline void *proc_sys_poll_event(struct ctl_table_poll *poll)
104 {
105 return (void *)(unsigned long)atomic_read(&poll->event);
106 }
107
108 #define __CTL_TABLE_POLL_INITIALIZER(name) { \
109 .event = ATOMIC_INIT(0), \
110 .wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.wait) }
111
112 #define DEFINE_CTL_TABLE_POLL(name) \
113 struct ctl_table_poll name = __CTL_TABLE_POLL_INITIALIZER(name)
114
115 /* A sysctl table is an array of struct ctl_table: */
116 struct ctl_table {
117 const char *procname; /* Text ID for /proc/sys, or zero */
118 void *data;
119 int maxlen;
120 umode_t mode;
121 struct ctl_table *child; /* Deprecated */
122 proc_handler *proc_handler; /* Callback for text formatting */
123 struct ctl_table_poll *poll;
124 void *extra1;
125 void *extra2;
126 } __randomize_layout;
127
128 struct ctl_node {
129 struct rb_node node;
130 struct ctl_table_header *header;
131 };
132
133 /* struct ctl_table_header is used to maintain dynamic lists of
134 struct ctl_table trees. */
135 struct ctl_table_header {
136 union {
137 struct {
138 struct ctl_table *ctl_table;
139 int used;
140 int count;
141 int nreg;
142 };
143 struct rcu_head rcu;
144 };
145 struct completion *unregistering;
146 struct ctl_table *ctl_table_arg;
147 struct ctl_table_root *root;
148 struct ctl_table_set *set;
149 struct ctl_dir *parent;
150 struct ctl_node *node;
151 struct hlist_head inodes; /* head for proc_inode->sysctl_inodes */
152 };
153
154 struct ctl_dir {
155 /* Header must be at the start of ctl_dir */
156 struct ctl_table_header header;
157 struct rb_root root;
158 };
159
160 struct ctl_table_set {
161 int (*is_seen)(struct ctl_table_set *);
162 struct ctl_dir dir;
163 };
164
165 struct ctl_table_root {
166 struct ctl_table_set default_set;
167 struct ctl_table_set *(*lookup)(struct ctl_table_root *root);
168 void (*set_ownership)(struct ctl_table_header *head,
169 struct ctl_table *table,
170 kuid_t *uid, kgid_t *gid);
171 int (*permissions)(struct ctl_table_header *head, struct ctl_table *table);
172 };
173
174 /* struct ctl_path describes where in the hierarchy a table is added */
175 struct ctl_path {
176 const char *procname;
177 };
178
179 #ifdef CONFIG_SYSCTL
180
181 void proc_sys_poll_notify(struct ctl_table_poll *poll);
182
183 extern void setup_sysctl_set(struct ctl_table_set *p,
184 struct ctl_table_root *root,
185 int (*is_seen)(struct ctl_table_set *));
186 extern void retire_sysctl_set(struct ctl_table_set *set);
187
188 struct ctl_table_header *__register_sysctl_table(
189 struct ctl_table_set *set,
190 const char *path, struct ctl_table *table);
191 struct ctl_table_header *__register_sysctl_paths(
192 struct ctl_table_set *set,
193 const struct ctl_path *path, struct ctl_table *table);
194 struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table);
195 struct ctl_table_header *register_sysctl_table(struct ctl_table * table);
196 struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
197 struct ctl_table *table);
198
199 void unregister_sysctl_table(struct ctl_table_header * table);
200
201 extern int sysctl_init(void);
202 void do_sysctl_args(void);
203
204 extern int pwrsw_enabled;
205 extern int unaligned_enabled;
206 extern int unaligned_dump_stack;
207 extern int no_unaligned_warning;
208
209 extern struct ctl_table sysctl_mount_point[];
210 extern struct ctl_table random_table[];
211 extern struct ctl_table firmware_config_table[];
212 extern struct ctl_table epoll_table[];
213
214 #else /* CONFIG_SYSCTL */
register_sysctl_table(struct ctl_table * table)215 static inline struct ctl_table_header *register_sysctl_table(struct ctl_table * table)
216 {
217 return NULL;
218 }
219
register_sysctl_paths(const struct ctl_path * path,struct ctl_table * table)220 static inline struct ctl_table_header *register_sysctl_paths(
221 const struct ctl_path *path, struct ctl_table *table)
222 {
223 return NULL;
224 }
225
register_sysctl(const char * path,struct ctl_table * table)226 static inline struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table)
227 {
228 return NULL;
229 }
230
unregister_sysctl_table(struct ctl_table_header * table)231 static inline void unregister_sysctl_table(struct ctl_table_header * table)
232 {
233 }
234
setup_sysctl_set(struct ctl_table_set * p,struct ctl_table_root * root,int (* is_seen)(struct ctl_table_set *))235 static inline void setup_sysctl_set(struct ctl_table_set *p,
236 struct ctl_table_root *root,
237 int (*is_seen)(struct ctl_table_set *))
238 {
239 }
240
do_sysctl_args(void)241 static inline void do_sysctl_args(void)
242 {
243 }
244 #endif /* CONFIG_SYSCTL */
245
246 int sysctl_max_threads(struct ctl_table *table, int write, void *buffer,
247 size_t *lenp, loff_t *ppos);
248
249 #endif /* _LINUX_SYSCTL_H */
250