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(const struct ctl_table *ctl, int write, void *buffer,
65 size_t *lenp, loff_t *ppos);
66
67 int proc_dostring(const struct ctl_table *, int, void *, size_t *, loff_t *);
68 int proc_dobool(const struct ctl_table *table, int write, void *buffer,
69 size_t *lenp, loff_t *ppos);
70 int proc_dointvec(const struct ctl_table *, int, void *, size_t *, loff_t *);
71 int proc_douintvec(const struct ctl_table *, int, void *, size_t *, loff_t *);
72 int proc_dointvec_minmax(const struct ctl_table *, int, void *, size_t *, loff_t *);
73 int proc_douintvec_minmax(const struct ctl_table *table, int write, void *buffer,
74 size_t *lenp, loff_t *ppos);
75 int proc_dou8vec_minmax(const struct ctl_table *table, int write, void *buffer,
76 size_t *lenp, loff_t *ppos);
77 int proc_dointvec_jiffies(const struct ctl_table *, int, void *, size_t *, loff_t *);
78 int proc_dointvec_ms_jiffies_minmax(const struct ctl_table *table, int write,
79 void *buffer, size_t *lenp, loff_t *ppos);
80 int proc_dointvec_userhz_jiffies(const struct ctl_table *, int, void *, size_t *,
81 loff_t *);
82 int proc_dointvec_ms_jiffies(const struct ctl_table *, int, void *, size_t *,
83 loff_t *);
84 int proc_doulongvec_minmax(const struct ctl_table *, int, void *, size_t *, loff_t *);
85 int proc_doulongvec_ms_jiffies_minmax(const struct ctl_table *table, int, void *,
86 size_t *, loff_t *);
87 int proc_do_large_bitmap(const struct ctl_table *, int, void *, size_t *, loff_t *);
88 int proc_do_static_key(const struct ctl_table *table, int write, void *buffer,
89 size_t *lenp, loff_t *ppos);
90
91 /*
92 * Register a set of sysctl names by calling register_sysctl
93 * with an initialised array of struct ctl_table's. An entry with
94 * NULL procname terminates the table. table->de will be
95 * set up by the registration and need not be initialised in advance.
96 *
97 * sysctl names can be mirrored automatically under /proc/sys. The
98 * procname supplied controls /proc naming.
99 *
100 * The table's mode will be honoured for proc-fs access.
101 *
102 * Leaf nodes in the sysctl tree will be represented by a single file
103 * under /proc; non-leaf nodes will be represented by directories. A
104 * null procname disables /proc mirroring at this node.
105 *
106 * The data and maxlen fields of the ctl_table
107 * struct enable minimal validation of the values being written to be
108 * performed, and the mode field allows minimal authentication.
109 *
110 * There must be a proc_handler routine for any terminal nodes
111 * mirrored under /proc/sys (non-terminals are handled by a built-in
112 * directory handler). Several default handlers are available to
113 * cover common cases.
114 */
115
116 /* Support for userspace poll() to watch for changes */
117 struct ctl_table_poll {
118 atomic_t event;
119 wait_queue_head_t wait;
120 };
121
122 static inline void *proc_sys_poll_event(struct ctl_table_poll *poll)
123 {
124 return (void *)(unsigned long)atomic_read(&poll->event);
125 }
126
127 #define __CTL_TABLE_POLL_INITIALIZER(name) { \
128 .event = ATOMIC_INIT(0), \
129 .wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.wait) }
130
131 #define DEFINE_CTL_TABLE_POLL(name) \
132 struct ctl_table_poll name = __CTL_TABLE_POLL_INITIALIZER(name)
133
134 /* A sysctl table is an array of struct ctl_table: */
135 struct ctl_table {
136 const char *procname; /* Text ID for /proc/sys, or zero */
137 void *data;
138 int maxlen;
139 umode_t mode;
140 proc_handler *proc_handler; /* Callback for text formatting */
141 struct ctl_table_poll *poll;
142 void *extra1;
143 void *extra2;
144 } __randomize_layout;
145
146 struct ctl_node {
147 struct rb_node node;
148 struct ctl_table_header *header;
149 };
150
151 /**
152 * struct ctl_table_header - maintains dynamic lists of struct ctl_table trees
153 * @ctl_table: pointer to the first element in ctl_table array
154 * @ctl_table_size: number of elements pointed by @ctl_table
155 * @used: The entry will never be touched when equal to 0.
156 * @count: Upped every time something is added to @inodes and downed every time
157 * something is removed from inodes
158 * @nreg: When nreg drops to 0 the ctl_table_header will be unregistered.
159 * @rcu: Delays the freeing of the inode. Introduced with "unfuck proc_sysctl ->d_compare()"
160 *
161 */
162 struct ctl_table_header {
163 union {
164 struct {
165 struct ctl_table *ctl_table;
166 int ctl_table_size;
167 int used;
168 int count;
169 int nreg;
170 };
171 struct rcu_head rcu;
172 };
173 struct completion *unregistering;
174 const struct ctl_table *ctl_table_arg;
175 struct ctl_table_root *root;
176 struct ctl_table_set *set;
177 struct ctl_dir *parent;
178 struct ctl_node *node;
179 struct hlist_head inodes; /* head for proc_inode->sysctl_inodes */
180 /**
181 * enum type - Enumeration to differentiate between ctl target types
182 * @SYSCTL_TABLE_TYPE_DEFAULT: ctl target with no special considerations
183 * @SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY: Used to identify a permanently
184 * empty directory target to serve
185 * as mount point.
186 */
187 enum {
188 SYSCTL_TABLE_TYPE_DEFAULT,
189 SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY,
190 } type;
191 };
192
193 struct ctl_dir {
194 /* Header must be at the start of ctl_dir */
195 struct ctl_table_header header;
196 struct rb_root root;
197 };
198
199 struct ctl_table_set {
200 int (*is_seen)(struct ctl_table_set *);
201 struct ctl_dir dir;
202 };
203
204 struct ctl_table_root {
205 struct ctl_table_set default_set;
206 struct ctl_table_set *(*lookup)(struct ctl_table_root *root);
207 void (*set_ownership)(struct ctl_table_header *head,
208 kuid_t *uid, kgid_t *gid);
209 int (*permissions)(struct ctl_table_header *head, const struct ctl_table *table);
210 };
211
212 #define register_sysctl(path, table) \
213 register_sysctl_sz(path, table, ARRAY_SIZE(table))
214
215 #ifdef CONFIG_SYSCTL
216
217 void proc_sys_poll_notify(struct ctl_table_poll *poll);
218
219 extern void setup_sysctl_set(struct ctl_table_set *p,
220 struct ctl_table_root *root,
221 int (*is_seen)(struct ctl_table_set *));
222 extern void retire_sysctl_set(struct ctl_table_set *set);
223
224 struct ctl_table_header *__register_sysctl_table(
225 struct ctl_table_set *set,
226 const char *path, struct ctl_table *table, size_t table_size);
227 struct ctl_table_header *register_sysctl_sz(const char *path, struct ctl_table *table,
228 size_t table_size);
229 void unregister_sysctl_table(struct ctl_table_header * table);
230
231 extern int sysctl_init_bases(void);
232 extern void __register_sysctl_init(const char *path, struct ctl_table *table,
233 const char *table_name, size_t table_size);
234 #define register_sysctl_init(path, table) \
235 __register_sysctl_init(path, table, #table, ARRAY_SIZE(table))
236 extern struct ctl_table_header *register_sysctl_mount_point(const char *path);
237
238 void do_sysctl_args(void);
239 bool sysctl_is_alias(char *param);
240 int do_proc_douintvec(const struct ctl_table *table, int write,
241 void *buffer, size_t *lenp, loff_t *ppos,
242 int (*conv)(unsigned long *lvalp,
243 unsigned int *valp,
244 int write, void *data),
245 void *data);
246
247 extern int pwrsw_enabled;
248 extern int unaligned_enabled;
249 extern int unaligned_dump_stack;
250 extern int no_unaligned_warning;
251
252 #else /* CONFIG_SYSCTL */
253
254 static inline void register_sysctl_init(const char *path, struct ctl_table *table)
255 {
256 }
257
258 static inline struct ctl_table_header *register_sysctl_mount_point(const char *path)
259 {
260 return NULL;
261 }
262
263 static inline struct ctl_table_header *register_sysctl_sz(const char *path,
264 struct ctl_table *table,
265 size_t table_size)
266 {
267 return NULL;
268 }
269
270 static inline void unregister_sysctl_table(struct ctl_table_header * table)
271 {
272 }
273
274 static inline void setup_sysctl_set(struct ctl_table_set *p,
275 struct ctl_table_root *root,
276 int (*is_seen)(struct ctl_table_set *))
277 {
278 }
279
280 static inline void do_sysctl_args(void)
281 {
282 }
283
284 static inline bool sysctl_is_alias(char *param)
285 {
286 return false;
287 }
288 #endif /* CONFIG_SYSCTL */
289
290 int sysctl_max_threads(const struct ctl_table *table, int write, void *buffer,
291 size_t *lenp, loff_t *ppos);
292
293 #endif /* _LINUX_SYSCTL_H */
294
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