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 typedef int proc_handler (struct ctl_table *ctl, int write,
41 void __user *buffer, size_t *lenp, loff_t *ppos);
42
43 extern int proc_dostring(struct ctl_table *, int,
44 void __user *, size_t *, loff_t *);
45 extern int proc_dointvec(struct ctl_table *, int,
46 void __user *, size_t *, loff_t *);
47 extern int proc_douintvec(struct ctl_table *, int,
48 void __user *, size_t *, loff_t *);
49 extern int proc_dointvec_minmax(struct ctl_table *, int,
50 void __user *, size_t *, loff_t *);
51 extern int proc_douintvec_minmax(struct ctl_table *table, int write,
52 void __user *buffer, size_t *lenp,
53 loff_t *ppos);
54 extern int proc_dointvec_jiffies(struct ctl_table *, int,
55 void __user *, size_t *, loff_t *);
56 extern int proc_dointvec_userhz_jiffies(struct ctl_table *, int,
57 void __user *, size_t *, loff_t *);
58 extern int proc_dointvec_ms_jiffies(struct ctl_table *, int,
59 void __user *, size_t *, loff_t *);
60 extern int proc_doulongvec_minmax(struct ctl_table *, int,
61 void __user *, size_t *, loff_t *);
62 extern int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int,
63 void __user *, size_t *, loff_t *);
64 extern int proc_do_large_bitmap(struct ctl_table *, int,
65 void __user *, size_t *, loff_t *);
66
67 /*
68 * Register a set of sysctl names by calling register_sysctl_table
69 * with an initialised array of struct ctl_table's. An entry with
70 * NULL procname terminates the table. table->de will be
71 * set up by the registration and need not be initialised in advance.
72 *
73 * sysctl names can be mirrored automatically under /proc/sys. The
74 * procname supplied controls /proc naming.
75 *
76 * The table's mode will be honoured both for sys_sysctl(2) and
77 * proc-fs access.
78 *
79 * Leaf nodes in the sysctl tree will be represented by a single file
80 * under /proc; non-leaf nodes will be represented by directories. A
81 * null procname disables /proc mirroring at this node.
82 *
83 * sysctl(2) can automatically manage read and write requests through
84 * the sysctl table. The data and maxlen fields of the ctl_table
85 * struct enable minimal validation of the values being written to be
86 * performed, and the mode field allows minimal authentication.
87 *
88 * There must be a proc_handler routine for any terminal nodes
89 * mirrored under /proc/sys (non-terminals are handled by a built-in
90 * directory handler). Several default handlers are available to
91 * cover common cases.
92 */
93
94 /* Support for userspace poll() to watch for changes */
95 struct ctl_table_poll {
96 atomic_t event;
97 wait_queue_head_t wait;
98 };
99
proc_sys_poll_event(struct ctl_table_poll * poll)100 static inline void *proc_sys_poll_event(struct ctl_table_poll *poll)
101 {
102 return (void *)(unsigned long)atomic_read(&poll->event);
103 }
104
105 #define __CTL_TABLE_POLL_INITIALIZER(name) { \
106 .event = ATOMIC_INIT(0), \
107 .wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.wait) }
108
109 #define DEFINE_CTL_TABLE_POLL(name) \
110 struct ctl_table_poll name = __CTL_TABLE_POLL_INITIALIZER(name)
111
112 /* A sysctl table is an array of struct ctl_table: */
113 struct ctl_table
114 {
115 const char *procname; /* Text ID for /proc/sys, or zero */
116 void *data;
117 int maxlen;
118 umode_t mode;
119 struct ctl_table *child; /* Deprecated */
120 proc_handler *proc_handler; /* Callback for text formatting */
121 struct ctl_table_poll *poll;
122 void *extra1;
123 void *extra2;
124 } __randomize_layout;
125
126 struct ctl_node {
127 struct rb_node node;
128 struct ctl_table_header *header;
129 };
130
131 /* struct ctl_table_header is used to maintain dynamic lists of
132 struct ctl_table trees. */
133 struct ctl_table_header
134 {
135 union {
136 struct {
137 struct ctl_table *ctl_table;
138 int used;
139 int count;
140 int nreg;
141 };
142 struct rcu_head rcu;
143 };
144 struct completion *unregistering;
145 struct ctl_table *ctl_table_arg;
146 struct ctl_table_root *root;
147 struct ctl_table_set *set;
148 struct ctl_dir *parent;
149 struct ctl_node *node;
150 struct hlist_head inodes; /* head for proc_inode->sysctl_inodes */
151 };
152
153 struct ctl_dir {
154 /* Header must be at the start of ctl_dir */
155 struct ctl_table_header header;
156 struct rb_root root;
157 };
158
159 struct ctl_table_set {
160 int (*is_seen)(struct ctl_table_set *);
161 struct ctl_dir dir;
162 };
163
164 struct ctl_table_root {
165 struct ctl_table_set default_set;
166 struct ctl_table_set *(*lookup)(struct ctl_table_root *root);
167 void (*set_ownership)(struct ctl_table_header *head,
168 struct ctl_table *table,
169 kuid_t *uid, kgid_t *gid);
170 int (*permissions)(struct ctl_table_header *head, struct ctl_table *table);
171 };
172
173 /* struct ctl_path describes where in the hierarchy a table is added */
174 struct ctl_path {
175 const char *procname;
176 };
177
178 #ifdef CONFIG_SYSCTL
179
180 void proc_sys_poll_notify(struct ctl_table_poll *poll);
181
182 extern void setup_sysctl_set(struct ctl_table_set *p,
183 struct ctl_table_root *root,
184 int (*is_seen)(struct ctl_table_set *));
185 extern void retire_sysctl_set(struct ctl_table_set *set);
186
187 struct ctl_table_header *__register_sysctl_table(
188 struct ctl_table_set *set,
189 const char *path, struct ctl_table *table);
190 struct ctl_table_header *__register_sysctl_paths(
191 struct ctl_table_set *set,
192 const struct ctl_path *path, struct ctl_table *table);
193 struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table);
194 struct ctl_table_header *register_sysctl_table(struct ctl_table * table);
195 struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
196 struct ctl_table *table);
197
198 void unregister_sysctl_table(struct ctl_table_header * table);
199
200 extern int sysctl_init(void);
201 extern void __register_sysctl_init(const char *path, struct ctl_table *table,
202 const char *table_name);
203 #define register_sysctl_init(path, table) __register_sysctl_init(path, table, #table)
204
205 extern struct ctl_table sysctl_mount_point[];
206
207 #else /* CONFIG_SYSCTL */
register_sysctl_table(struct ctl_table * table)208 static inline struct ctl_table_header *register_sysctl_table(struct ctl_table * table)
209 {
210 return NULL;
211 }
212
register_sysctl_paths(const struct ctl_path * path,struct ctl_table * table)213 static inline struct ctl_table_header *register_sysctl_paths(
214 const struct ctl_path *path, struct ctl_table *table)
215 {
216 return NULL;
217 }
218
register_sysctl(const char * path,struct ctl_table * table)219 static inline struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table)
220 {
221 return NULL;
222 }
223
unregister_sysctl_table(struct ctl_table_header * table)224 static inline void unregister_sysctl_table(struct ctl_table_header * table)
225 {
226 }
227
setup_sysctl_set(struct ctl_table_set * p,struct ctl_table_root * root,int (* is_seen)(struct ctl_table_set *))228 static inline void setup_sysctl_set(struct ctl_table_set *p,
229 struct ctl_table_root *root,
230 int (*is_seen)(struct ctl_table_set *))
231 {
232 }
233
234 #endif /* CONFIG_SYSCTL */
235
236 int sysctl_max_threads(struct ctl_table *table, int write,
237 void __user *buffer, size_t *lenp, loff_t *ppos);
238
239 #endif /* _LINUX_SYSCTL_H */
240