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