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