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 <linux/uidgid.h>
  29 #include <uapi/linux/sysctl.h>
  30
  31 /* For the /proc/sys support */
  32 struct completion;
  33 struct ctl_table;
  34 struct nsproxy;
  35 struct ctl_table_root;
  36 struct ctl_table_header;
  37 struct ctl_dir;
  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_douintvec(struct ctl_table *, int,
  47                          void __user *, size_t *, loff_t *);
  48 extern int proc_dointvec_minmax(struct ctl_table *, int,
  49                                 void __user *, size_t *, loff_t *);
  50 extern int proc_douintvec_minmax(struct ctl_table *table, int write,
  51                                  void __user *buffer, size_t *lenp,
  52                                  loff_t *ppos);
  53 extern int proc_dointvec_jiffies(struct ctl_table *, int,
  54                                  void __user *, size_t *, loff_t *);
  55 extern int proc_dointvec_userhz_jiffies(struct ctl_table *, int,
  56                                         void __user *, size_t *, loff_t *);
  57 extern int proc_dointvec_ms_jiffies(struct ctl_table *, int,
  58                                     void __user *, size_t *, loff_t *);
  59 extern int proc_doulongvec_minmax(struct ctl_table *, int,
  60                                   void __user *, size_t *, loff_t *);
  61 extern int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int,
  62                                       void __user *, size_t *, loff_t *);
  63 extern int proc_do_large_bitmap(struct ctl_table *, int,
  64                                 void __user *, size_t *, loff_t *);
  65
  66 /*
  67  * Register a set of sysctl names by calling register_sysctl_table
  68  * with an initialised array of struct ctl_table's.  An entry with
  69  * NULL procname terminates the table.  table->de will be
  70  * set up by the registration and need not be initialised in advance.
  71  *
  72  * sysctl names can be mirrored automatically under /proc/sys.  The
  73  * procname supplied controls /proc naming.
  74  *
  75  * The table's mode will be honoured both for sys_sysctl(2) and
  76  * proc-fs access.
  77  *
  78  * Leaf nodes in the sysctl tree will be represented by a single file
  79  * under /proc; non-leaf nodes will be represented by directories.  A
  80  * null procname disables /proc mirroring at this node.
  81  *
  82  * sysctl(2) can automatically manage read and write requests through
  83  * the sysctl table.  The data and maxlen fields of the ctl_table
  84  * struct enable minimal validation of the values being written to be
  85  * performed, and the mode field allows minimal authentication.
  86  *
  87  * There must be a proc_handler routine for any terminal nodes
  88  * mirrored under /proc/sys (non-terminals are handled by a built-in
  89  * directory handler).  Several default handlers are available to
  90  * cover common cases.
  91  */
  92
  93 /* Support for userspace poll() to watch for changes */
  94 struct ctl_table_poll {
  95         atomic_t event;
  96         wait_queue_head_t wait;
  97 };
  98
  99 static inline void *proc_sys_poll_event(struct ctl_table_poll *poll)
 100 {
 101         return (void *)(unsigned long)atomic_read(&poll->event);
 102 }
 103
 104 #define __CTL_TABLE_POLL_INITIALIZER(name) {                            \
 105         .event = ATOMIC_INIT(0),                                        \
 106         .wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.wait) }
 107
 108 #define DEFINE_CTL_TABLE_POLL(name)                                     \
 109         struct ctl_table_poll name = __CTL_TABLE_POLL_INITIALIZER(name)
 110
 111 /* A sysctl table is an array of struct ctl_table: */
 112 struct ctl_table
 113 {
 114         const char *procname;           /* Text ID for /proc/sys, or zero */
 115         void *data;
 116         int maxlen;
 117         umode_t mode;
 118         struct ctl_table *child;        /* Deprecated */
 119         proc_handler *proc_handler;     /* Callback for text formatting */
 120         struct ctl_table_poll *poll;
 121         void *extra1;
 122         void *extra2;
 123 };
 124
 125 struct ctl_node {
 126         struct rb_node node;
 127         struct ctl_table_header *header;
 128 };
 129
 130 /* struct ctl_table_header is used to maintain dynamic lists of
 131    struct ctl_table trees. */
 132 struct ctl_table_header
 133 {
 134         union {
 135                 struct {
 136                         struct ctl_table *ctl_table;
 137                         int used;
 138                         int count;
 139                         int nreg;
 140                 };
 141                 struct rcu_head rcu;
 142         };
 143         struct completion *unregistering;
 144         struct ctl_table *ctl_table_arg;
 145         struct ctl_table_root *root;
 146         struct ctl_table_set *set;
 147         struct ctl_dir *parent;
 148         struct ctl_node *node;
 149         struct hlist_head inodes; /* head for proc_inode->sysctl_inodes */
 150 };
 151
 152 struct ctl_dir {
 153         /* Header must be at the start of ctl_dir */
 154         struct ctl_table_header header;
 155         struct rb_root root;
 156 };
 157
 158 struct ctl_table_set {
 159         int (*is_seen)(struct ctl_table_set *);
 160         struct ctl_dir dir;
 161 };
 162
 163 struct ctl_table_root {
 164         struct ctl_table_set default_set;
 165         struct ctl_table_set *(*lookup)(struct ctl_table_root *root);
 166         void (*set_ownership)(struct ctl_table_header *head,
 167                               struct ctl_table *table,
 168                               kuid_t *uid, kgid_t *gid);
 169         int (*permissions)(struct ctl_table_header *head, struct ctl_table *table);
 170 };
 171
 172 /* struct ctl_path describes where in the hierarchy a table is added */
 173 struct ctl_path {
 174         const char *procname;
 175 };
 176
 177 #ifdef CONFIG_SYSCTL
 178
 179 void proc_sys_poll_notify(struct ctl_table_poll *poll);
 180
 181 extern void setup_sysctl_set(struct ctl_table_set *p,
 182         struct ctl_table_root *root,
 183         int (*is_seen)(struct ctl_table_set *));
 184 extern void retire_sysctl_set(struct ctl_table_set *set);
 185
 186 struct ctl_table_header *__register_sysctl_table(
 187         struct ctl_table_set *set,
 188         const char *path, struct ctl_table *table);
 189 struct ctl_table_header *__register_sysctl_paths(
 190         struct ctl_table_set *set,
 191         const struct ctl_path *path, struct ctl_table *table);
 192 struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table);
 193 struct ctl_table_header *register_sysctl_table(struct ctl_table * table);
 194 struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
 195                                                 struct ctl_table *table);
 196
 197 void unregister_sysctl_table(struct ctl_table_header * table);
 198
 199 extern int sysctl_init(void);
 200
 201 extern struct ctl_table sysctl_mount_point[];
 202
 203 #else /* CONFIG_SYSCTL */
 204 static inline struct ctl_table_header *register_sysctl_table(struct ctl_table * table)
 205 {
 206         return NULL;
 207 }
 208
 209 static inline struct ctl_table_header *register_sysctl_paths(
 210                         const struct ctl_path *path, struct ctl_table *table)
 211 {
 212         return NULL;
 213 }
 214
 215 static inline void unregister_sysctl_table(struct ctl_table_header * table)
 216 {
 217 }
 218
 219 static inline void setup_sysctl_set(struct ctl_table_set *p,
 220         struct ctl_table_root *root,
 221         int (*is_seen)(struct ctl_table_set *))
 222 {
 223 }
 224
 225 #endif /* CONFIG_SYSCTL */
 226
 227 int sysctl_max_threads(struct ctl_table *table, int write,
 228                        void __user *buffer, size_t *lenp, loff_t *ppos);
 229
 230 #endif /* _LINUX_SYSCTL_H */