LXR linux/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 */
  32struct completion;
  33struct ctl_table;
  34struct nsproxy;
  35struct ctl_table_root;
  36struct ctl_table_header;
  37struct ctl_dir;
  38
  39typedef int proc_handler (struct ctl_table *ctl, int write,
  40                          void __user *buffer, size_t *lenp, loff_t *ppos);
  41
  42extern int proc_dostring(struct ctl_table *, int,
  43                         void __user *, size_t *, loff_t *);
  44extern int proc_dointvec(struct ctl_table *, int,
  45                         void __user *, size_t *, loff_t *);
  46extern int proc_douintvec(struct ctl_table *, int,
  47                         void __user *, size_t *, loff_t *);
  48extern int proc_dointvec_minmax(struct ctl_table *, int,
  49                                void __user *, size_t *, loff_t *);
  50extern int proc_dointvec_jiffies(struct ctl_table *, int,
  51                                 void __user *, size_t *, loff_t *);
  52extern int proc_dointvec_userhz_jiffies(struct ctl_table *, int,
  53                                        void __user *, size_t *, loff_t *);
  54extern int proc_dointvec_ms_jiffies(struct ctl_table *, int,
  55                                    void __user *, size_t *, loff_t *);
  56extern int proc_doulongvec_minmax(struct ctl_table *, int,
  57                                  void __user *, size_t *, loff_t *);
  58extern int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int,
  59                                      void __user *, size_t *, loff_t *);
  60extern 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 */
  91struct ctl_table_poll {
  92        atomic_t event;
  93        wait_queue_head_t wait;
  94};
  95
  96static 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: */
 109struct 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
 122struct 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. */
 129struct 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        struct list_head inodes; /* head for proc_inode->sysctl_inodes */
 147};
 148
 149struct ctl_dir {
 150        /* Header must be at the start of ctl_dir */
 151        struct ctl_table_header header;
 152        struct rb_root root;
 153};
 154
 155struct ctl_table_set {
 156        int (*is_seen)(struct ctl_table_set *);
 157        struct ctl_dir dir;
 158};
 159
 160struct ctl_table_root {
 161        struct ctl_table_set default_set;
 162        struct ctl_table_set *(*lookup)(struct ctl_table_root *root);
 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 */
 170struct ctl_path {
 171        const char *procname;
 172};
 173
 174#ifdef CONFIG_SYSCTL
 175
 176void proc_sys_poll_notify(struct ctl_table_poll *poll);
 177
 178extern void setup_sysctl_set(struct ctl_table_set *p,
 179        struct ctl_table_root *root,
 180        int (*is_seen)(struct ctl_table_set *));
 181extern void retire_sysctl_set(struct ctl_table_set *set);
 182
 183struct ctl_table_header *__register_sysctl_table(
 184        struct ctl_table_set *set,
 185        const char *path, struct ctl_table *table);
 186struct ctl_table_header *__register_sysctl_paths(
 187        struct ctl_table_set *set,
 188        const struct ctl_path *path, struct ctl_table *table);
 189struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table);
 190struct ctl_table_header *register_sysctl_table(struct ctl_table * table);
 191struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
 192                                                struct ctl_table *table);
 193
 194void unregister_sysctl_table(struct ctl_table_header * table);
 195
 196extern int sysctl_init(void);
 197
 198extern struct ctl_table sysctl_mount_point[];
 199
 200#else /* CONFIG_SYSCTL */
 201static inline struct ctl_table_header *register_sysctl_table(struct ctl_table * table)
 202{
 203        return NULL;
 204}
 205
 206static inline struct ctl_table_header *register_sysctl_paths(
 207                        const struct ctl_path *path, struct ctl_table *table)
 208{
 209        return NULL;
 210}
 211
 212static inline void unregister_sysctl_table(struct ctl_table_header * table)
 213{
 214}
 215
 216static inline void setup_sysctl_set(struct ctl_table_set *p,
 217        struct ctl_table_root *root,
 218        int (*is_seen)(struct ctl_table_set *))
 219{
 220}
 221
 222#endif /* CONFIG_SYSCTL */
 223
 224int sysctl_max_threads(struct ctl_table *table, int write,
 225                       void __user *buffer, size_t *lenp, loff_t *ppos);
 226
 227#endif /* _LINUX_SYSCTL_H */
 228