• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
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