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1/*
2 * sysctl.h: General linux system control interface
3 *
4 * Begun 24 March 1995, Stephen Tweedie
5 *
6 ****************************************************************
7 ****************************************************************
8 **
9 ** WARNING:
10 ** The values in this file are exported to user space via
11 ** the sysctl() binary interface. Do *NOT* change the
12 ** numbering of any existing values here, and do not change
13 ** any numbers within any one set of values. If you have to
14 ** redefine an existing interface, use a new number for it.
15 ** The kernel will then return -ENOTDIR to any application using
16 ** the old binary interface.
17 **
18 ****************************************************************
19 ****************************************************************
20 */
21#ifndef _LINUX_SYSCTL_H
22#define _LINUX_SYSCTL_H
23
24#include <linux/list.h>
25#include <linux/rcupdate.h>
26#include <linux/wait.h>
27#include <linux/rbtree.h>
28#include <linux/uidgid.h>
29#include <uapi/linux/sysctl.h>
30
31/* For the /proc/sys support */
32struct completion;
33struct ctl_table;
34struct nsproxy;
35struct ctl_table_root;
36struct ctl_table_header;
37struct ctl_dir;
38
39typedef int proc_handler (struct ctl_table *ctl, int write,
40 void __user *buffer, size_t *lenp, loff_t *ppos);
41
42extern int proc_dostring(struct ctl_table *, int,
43 void __user *, size_t *, loff_t *);
44extern int proc_dointvec(struct ctl_table *, int,
45 void __user *, size_t *, loff_t *);
46extern int proc_douintvec(struct ctl_table *, int,
47 void __user *, size_t *, loff_t *);
48extern int proc_dointvec_minmax(struct ctl_table *, int,
49 void __user *, size_t *, loff_t *);
50extern int proc_douintvec_minmax(struct ctl_table *table, int write,
51 void __user *buffer, size_t *lenp,
52 loff_t *ppos);
53extern int proc_dointvec_jiffies(struct ctl_table *, int,
54 void __user *, size_t *, loff_t *);
55extern int proc_dointvec_userhz_jiffies(struct ctl_table *, int,
56 void __user *, size_t *, loff_t *);
57extern int proc_dointvec_ms_jiffies(struct ctl_table *, int,
58 void __user *, size_t *, loff_t *);
59extern int proc_doulongvec_minmax(struct ctl_table *, int,
60 void __user *, size_t *, loff_t *);
61extern int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int,
62 void __user *, size_t *, loff_t *);
63extern int proc_do_large_bitmap(struct ctl_table *, int,
64 void __user *, size_t *, loff_t *);
65
66/*
67 * Register a set of sysctl names by calling register_sysctl_table
68 * with an initialised array of struct ctl_table's. An entry with
69 * NULL procname terminates the table. table->de will be
70 * set up by the registration and need not be initialised in advance.
71 *
72 * sysctl names can be mirrored automatically under /proc/sys. The
73 * procname supplied controls /proc naming.
74 *
75 * The table's mode will be honoured both for sys_sysctl(2) and
76 * proc-fs access.
77 *
78 * Leaf nodes in the sysctl tree will be represented by a single file
79 * under /proc; non-leaf nodes will be represented by directories. A
80 * null procname disables /proc mirroring at this node.
81 *
82 * sysctl(2) can automatically manage read and write requests through
83 * the sysctl table. The data and maxlen fields of the ctl_table
84 * struct enable minimal validation of the values being written to be
85 * performed, and the mode field allows minimal authentication.
86 *
87 * There must be a proc_handler routine for any terminal nodes
88 * mirrored under /proc/sys (non-terminals are handled by a built-in
89 * directory handler). Several default handlers are available to
90 * cover common cases.
91 */
92
93/* Support for userspace poll() to watch for changes */
94struct ctl_table_poll {
95 atomic_t event;
96 wait_queue_head_t wait;
97};
98
99static inline void *proc_sys_poll_event(struct ctl_table_poll *poll)
100{
101 return (void *)(unsigned long)atomic_read(&poll->event);
102}
103
104#define __CTL_TABLE_POLL_INITIALIZER(name) { \
105 .event = ATOMIC_INIT(0), \
106 .wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.wait) }
107
108#define DEFINE_CTL_TABLE_POLL(name) \
109 struct ctl_table_poll name = __CTL_TABLE_POLL_INITIALIZER(name)
110
111/* A sysctl table is an array of struct ctl_table: */
112struct ctl_table
113{
114 const char *procname; /* Text ID for /proc/sys, or zero */
115 void *data;
116 int maxlen;
117 umode_t mode;
118 struct ctl_table *child; /* Deprecated */
119 proc_handler *proc_handler; /* Callback for text formatting */
120 struct ctl_table_poll *poll;
121 void *extra1;
122 void *extra2;
123} __randomize_layout;
124
125struct ctl_node {
126 struct rb_node node;
127 struct ctl_table_header *header;
128};
129
130/* struct ctl_table_header is used to maintain dynamic lists of
131 struct ctl_table trees. */
132struct ctl_table_header
133{
134 union {
135 struct {
136 struct ctl_table *ctl_table;
137 int used;
138 int count;
139 int nreg;
140 };
141 struct rcu_head rcu;
142 };
143 struct completion *unregistering;
144 struct ctl_table *ctl_table_arg;
145 struct ctl_table_root *root;
146 struct ctl_table_set *set;
147 struct ctl_dir *parent;
148 struct ctl_node *node;
149 struct hlist_head inodes; /* head for proc_inode->sysctl_inodes */
150};
151
152struct ctl_dir {
153 /* Header must be at the start of ctl_dir */
154 struct ctl_table_header header;
155 struct rb_root root;
156};
157
158struct ctl_table_set {
159 int (*is_seen)(struct ctl_table_set *);
160 struct ctl_dir dir;
161};
162
163struct ctl_table_root {
164 struct ctl_table_set default_set;
165 struct ctl_table_set *(*lookup)(struct ctl_table_root *root);
166 void (*set_ownership)(struct ctl_table_header *head,
167 struct ctl_table *table,
168 kuid_t *uid, kgid_t *gid);
169 int (*permissions)(struct ctl_table_header *head, struct ctl_table *table);
170};
171
172/* struct ctl_path describes where in the hierarchy a table is added */
173struct ctl_path {
174 const char *procname;
175};
176
177#ifdef CONFIG_SYSCTL
178
179void proc_sys_poll_notify(struct ctl_table_poll *poll);
180
181extern void setup_sysctl_set(struct ctl_table_set *p,
182 struct ctl_table_root *root,
183 int (*is_seen)(struct ctl_table_set *));
184extern void retire_sysctl_set(struct ctl_table_set *set);
185
186struct ctl_table_header *__register_sysctl_table(
187 struct ctl_table_set *set,
188 const char *path, struct ctl_table *table);
189struct ctl_table_header *__register_sysctl_paths(
190 struct ctl_table_set *set,
191 const struct ctl_path *path, struct ctl_table *table);
192struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table);
193struct ctl_table_header *register_sysctl_table(struct ctl_table * table);
194struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
195 struct ctl_table *table);
196
197void unregister_sysctl_table(struct ctl_table_header * table);
198
199extern int sysctl_init(void);
200
201extern struct ctl_table sysctl_mount_point[];
202
203#else /* CONFIG_SYSCTL */
204static inline struct ctl_table_header *register_sysctl_table(struct ctl_table * table)
205{
206 return NULL;
207}
208
209static inline struct ctl_table_header *register_sysctl_paths(
210 const struct ctl_path *path, struct ctl_table *table)
211{
212 return NULL;
213}
214
215static inline void unregister_sysctl_table(struct ctl_table_header * table)
216{
217}
218
219static inline void setup_sysctl_set(struct ctl_table_set *p,
220 struct ctl_table_root *root,
221 int (*is_seen)(struct ctl_table_set *))
222{
223}
224
225#endif /* CONFIG_SYSCTL */
226
227int sysctl_max_threads(struct ctl_table *table, int write,
228 void __user *buffer, size_t *lenp, loff_t *ppos);
229
230#endif /* _LINUX_SYSCTL_H */