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