root/include/linux/sysctl.h

INCLUDED FROM

DEFINITIONS

1. proc_sys_poll_event
2. register_sysctl_table
3. register_sysctl_paths
4. register_sysctl
5. unregister_sysctl_table
6. setup_sysctl_set

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * sysctl.h: General linux system control interface
   4  *
   5  * Begun 24 March 1995, Stephen Tweedie
   6  *
   7  ****************************************************************
   8  ****************************************************************
   9  **
  10  **  WARNING:
  11  **  The values in this file are exported to user space via 
  12  **  the sysctl() binary interface.  Do *NOT* change the
  13  **  numbering of any existing values here, and do not change
  14  **  any numbers within any one set of values.  If you have to
  15  **  redefine an existing interface, use a new number for it.
  16  **  The kernel will then return -ENOTDIR to any application using
  17  **  the old binary interface.
  18  **
  19  ****************************************************************
  20  ****************************************************************
  21  */
  22 #ifndef _LINUX_SYSCTL_H
  23 #define _LINUX_SYSCTL_H
  24 
  25 #include <linux/list.h>
  26 #include <linux/rcupdate.h>
  27 #include <linux/wait.h>
  28 #include <linux/rbtree.h>
  29 #include <linux/uidgid.h>
  30 #include <uapi/linux/sysctl.h>
  31 
  32 /* For the /proc/sys support */
  33 struct completion;
  34 struct ctl_table;
  35 struct nsproxy;
  36 struct ctl_table_root;
  37 struct ctl_table_header;
  38 struct ctl_dir;
  39 
  40 /* Keep the same order as in fs/proc/proc_sysctl.c */
  41 #define SYSCTL_ZERO     ((void *)&sysctl_vals[0])
  42 #define SYSCTL_ONE      ((void *)&sysctl_vals[1])
  43 #define SYSCTL_INT_MAX  ((void *)&sysctl_vals[2])
  44 
  45 extern const int sysctl_vals[];
  46 
  47 typedef int proc_handler (struct ctl_table *ctl, int write,
  48                           void __user *buffer, size_t *lenp, loff_t *ppos);
  49 
  50 extern int proc_dostring(struct ctl_table *, int,
  51                          void __user *, size_t *, loff_t *);
  52 extern int proc_dointvec(struct ctl_table *, int,
  53                          void __user *, size_t *, loff_t *);
  54 extern int proc_douintvec(struct ctl_table *, int,
  55                          void __user *, size_t *, loff_t *);
  56 extern int proc_dointvec_minmax(struct ctl_table *, int,
  57                                 void __user *, size_t *, loff_t *);
  58 extern int proc_douintvec_minmax(struct ctl_table *table, int write,
  59                                  void __user *buffer, size_t *lenp,
  60                                  loff_t *ppos);
  61 extern int proc_dointvec_jiffies(struct ctl_table *, int,
  62                                  void __user *, size_t *, loff_t *);
  63 extern int proc_dointvec_userhz_jiffies(struct ctl_table *, int,
  64                                         void __user *, size_t *, loff_t *);
  65 extern int proc_dointvec_ms_jiffies(struct ctl_table *, int,
  66                                     void __user *, size_t *, loff_t *);
  67 extern int proc_doulongvec_minmax(struct ctl_table *, int,
  68                                   void __user *, size_t *, loff_t *);
  69 extern int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int,
  70                                       void __user *, size_t *, loff_t *);
  71 extern int proc_do_large_bitmap(struct ctl_table *, int,
  72                                 void __user *, size_t *, loff_t *);
  73 extern int proc_do_static_key(struct ctl_table *table, int write,
  74                               void __user *buffer, size_t *lenp,
  75                               loff_t *ppos);
  76 
  77 /*
  78  * Register a set of sysctl names by calling register_sysctl_table
  79  * with an initialised array of struct ctl_table's.  An entry with 
  80  * NULL procname terminates the table.  table->de will be
  81  * set up by the registration and need not be initialised in advance.
  82  *
  83  * sysctl names can be mirrored automatically under /proc/sys.  The
  84  * procname supplied controls /proc naming.
  85  *
  86  * The table's mode will be honoured both for sys_sysctl(2) and
  87  * proc-fs access.
  88  *
  89  * Leaf nodes in the sysctl tree will be represented by a single file
  90  * under /proc; non-leaf nodes will be represented by directories.  A
  91  * null procname disables /proc mirroring at this node.
  92  *
  93  * sysctl(2) can automatically manage read and write requests through
  94  * the sysctl table.  The data and maxlen fields of the ctl_table
  95  * struct enable minimal validation of the values being written to be
  96  * performed, and the mode field allows minimal authentication.
  97  * 
  98  * There must be a proc_handler routine for any terminal nodes
  99  * mirrored under /proc/sys (non-terminals are handled by a built-in
 100  * directory handler).  Several default handlers are available to
 101  * cover common cases.
 102  */
 103 
 104 /* Support for userspace poll() to watch for changes */
 105 struct ctl_table_poll {
 106         atomic_t event;
 107         wait_queue_head_t wait;
 108 };
 109 
 110 static inline void *proc_sys_poll_event(struct ctl_table_poll *poll)
 111 {
 112         return (void *)(unsigned long)atomic_read(&poll->event);
 113 }
 114 
 115 #define __CTL_TABLE_POLL_INITIALIZER(name) {                            \
 116         .event = ATOMIC_INIT(0),                                        \
 117         .wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.wait) }
 118 
 119 #define DEFINE_CTL_TABLE_POLL(name)                                     \
 120         struct ctl_table_poll name = __CTL_TABLE_POLL_INITIALIZER(name)
 121 
 122 /* A sysctl table is an array of struct ctl_table: */
 123 struct ctl_table 
 124 {
 125         const char *procname;           /* Text ID for /proc/sys, or zero */
 126         void *data;
 127         int maxlen;
 128         umode_t mode;
 129         struct ctl_table *child;        /* Deprecated */
 130         proc_handler *proc_handler;     /* Callback for text formatting */
 131         struct ctl_table_poll *poll;
 132         void *extra1;
 133         void *extra2;
 134 } __randomize_layout;
 135 
 136 struct ctl_node {
 137         struct rb_node node;
 138         struct ctl_table_header *header;
 139 };
 140 
 141 /* struct ctl_table_header is used to maintain dynamic lists of
 142    struct ctl_table trees. */
 143 struct ctl_table_header
 144 {
 145         union {
 146                 struct {
 147                         struct ctl_table *ctl_table;
 148                         int used;
 149                         int count;
 150                         int nreg;
 151                 };
 152                 struct rcu_head rcu;
 153         };
 154         struct completion *unregistering;
 155         struct ctl_table *ctl_table_arg;
 156         struct ctl_table_root *root;
 157         struct ctl_table_set *set;
 158         struct ctl_dir *parent;
 159         struct ctl_node *node;
 160         struct hlist_head inodes; /* head for proc_inode->sysctl_inodes */
 161 };
 162 
 163 struct ctl_dir {
 164         /* Header must be at the start of ctl_dir */
 165         struct ctl_table_header header;
 166         struct rb_root root;
 167 };
 168 
 169 struct ctl_table_set {
 170         int (*is_seen)(struct ctl_table_set *);
 171         struct ctl_dir dir;
 172 };
 173 
 174 struct ctl_table_root {
 175         struct ctl_table_set default_set;
 176         struct ctl_table_set *(*lookup)(struct ctl_table_root *root);
 177         void (*set_ownership)(struct ctl_table_header *head,
 178                               struct ctl_table *table,
 179                               kuid_t *uid, kgid_t *gid);
 180         int (*permissions)(struct ctl_table_header *head, struct ctl_table *table);
 181 };
 182 
 183 /* struct ctl_path describes where in the hierarchy a table is added */
 184 struct ctl_path {
 185         const char *procname;
 186 };
 187 
 188 #ifdef CONFIG_SYSCTL
 189 
 190 void proc_sys_poll_notify(struct ctl_table_poll *poll);
 191 
 192 extern void setup_sysctl_set(struct ctl_table_set *p,
 193         struct ctl_table_root *root,
 194         int (*is_seen)(struct ctl_table_set *));
 195 extern void retire_sysctl_set(struct ctl_table_set *set);
 196 
 197 struct ctl_table_header *__register_sysctl_table(
 198         struct ctl_table_set *set,
 199         const char *path, struct ctl_table *table);
 200 struct ctl_table_header *__register_sysctl_paths(
 201         struct ctl_table_set *set,
 202         const struct ctl_path *path, struct ctl_table *table);
 203 struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table);
 204 struct ctl_table_header *register_sysctl_table(struct ctl_table * table);
 205 struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
 206                                                 struct ctl_table *table);
 207 
 208 void unregister_sysctl_table(struct ctl_table_header * table);
 209 
 210 extern int sysctl_init(void);
 211 
 212 extern struct ctl_table sysctl_mount_point[];
 213 
 214 #else /* CONFIG_SYSCTL */
 215 static inline struct ctl_table_header *register_sysctl_table(struct ctl_table * table)
 216 {
 217         return NULL;
 218 }
 219 
 220 static inline struct ctl_table_header *register_sysctl_paths(
 221                         const struct ctl_path *path, struct ctl_table *table)
 222 {
 223         return NULL;
 224 }
 225 
 226 static inline struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table)
 227 {
 228         return NULL;
 229 }
 230 
 231 static inline void unregister_sysctl_table(struct ctl_table_header * table)
 232 {
 233 }
 234 
 235 static inline void setup_sysctl_set(struct ctl_table_set *p,
 236         struct ctl_table_root *root,
 237         int (*is_seen)(struct ctl_table_set *))
 238 {
 239 }
 240 
 241 #endif /* CONFIG_SYSCTL */
 242 
 243 int sysctl_max_threads(struct ctl_table *table, int write,
 244                        void __user *buffer, size_t *lenp, loff_t *ppos);
 245 
 246 #endif /* _LINUX_SYSCTL_H */