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 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
  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 */
 194 static inline struct ctl_table_header *register_sysctl_table(struct ctl_table * table)
 195 {
 196         return NULL;
 197 }
 198
 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
 205 static inline void unregister_sysctl_table(struct ctl_table_header * table)
 206 {
 207 }
 208
 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 */