include/linux/sysctl.h

   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 completion;
  32 struct ctl_table;
  33 struct nsproxy;
  34 struct ctl_table_root;
  35 struct ctl_table_header;
  36 struct ctl_dir;
  37
  38 typedef int proc_handler (struct ctl_table *ctl, int write,
  39                           void __user *buffer, size_t *lenp, loff_t *ppos);
  40
  41 extern int proc_dostring(struct ctl_table *, int,
  42                          void __user *, size_t *, loff_t *);
  43 extern int proc_dointvec(struct ctl_table *, int,
  44                          void __user *, size_t *, loff_t *);
  45 extern int proc_douintvec(struct ctl_table *, int,
  46                          void __user *, size_t *, loff_t *);
  47 extern int proc_dointvec_minmax(struct ctl_table *, int,
  48                                 void __user *, size_t *, loff_t *);
  49 extern int proc_dointvec_jiffies(struct ctl_table *, int,
  50                                  void __user *, size_t *, loff_t *);
  51 extern int proc_dointvec_userhz_jiffies(struct ctl_table *, int,
  52                                         void __user *, size_t *, loff_t *);
  53 extern int proc_dointvec_ms_jiffies(struct ctl_table *, int,
  54                                     void __user *, size_t *, loff_t *);
  55 extern int proc_doulongvec_minmax(struct ctl_table *, int,
  56                                   void __user *, size_t *, loff_t *);
  57 extern int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int,
  58                                       void __user *, size_t *, loff_t *);
  59 extern 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 */
  90 struct ctl_table_poll {
  91         atomic_t event;
  92         wait_queue_head_t wait;
  93 };
  94
  95 static 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: */
 108 struct 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
 121 struct 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. */
 128 struct 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
 147 struct 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
 153 struct ctl_table_set {
 154         int (*is_seen)(struct ctl_table_set *);
 155         struct ctl_dir dir;
 156 };
 157
 158 struct 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 */
 166 struct ctl_path {
 167         const char *procname;
 168 };
 169
 170 #ifdef CONFIG_SYSCTL
 171
 172 void proc_sys_poll_notify(struct ctl_table_poll *poll);
 173
 174 extern void setup_sysctl_set(struct ctl_table_set *p,
 175         struct ctl_table_root *root,
 176         int (*is_seen)(struct ctl_table_set *));
 177 extern void retire_sysctl_set(struct ctl_table_set *set);
 178
 179 void register_sysctl_root(struct ctl_table_root *root);
 180 struct ctl_table_header *__register_sysctl_table(
 181         struct ctl_table_set *set,
 182         const char *path, struct ctl_table *table);
 183 struct ctl_table_header *__register_sysctl_paths(
 184         struct ctl_table_set *set,
 185         const struct ctl_path *path, struct ctl_table *table);
 186 struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table);
 187 struct ctl_table_header *register_sysctl_table(struct ctl_table * table);
 188 struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
 189                                                 struct ctl_table *table);
 190
 191 void unregister_sysctl_table(struct ctl_table_header * table);
 192
 193 extern int sysctl_init(void);
 194
 195 extern struct ctl_table sysctl_mount_point[];
 196
 197 #else /* CONFIG_SYSCTL */
 198 static inline struct ctl_table_header *register_sysctl_table(struct ctl_table * table)
 199 {
 200         return NULL;
 201 }
 202
 203 static inline struct ctl_table_header *register_sysctl_paths(
 204                         const struct ctl_path *path, struct ctl_table *table)
 205 {
 206         return NULL;
 207 }
 208
 209 static inline void unregister_sysctl_table(struct ctl_table_header * table)
 210 {
 211 }
 212
 213 static 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
 221 int 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 */