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