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 int proc_handler (struct ctl_table *ctl, int write, 38 void __user *buffer, size_t *lenp, loff_t *ppos); 39 40 extern int proc_dostring(struct ctl_table *, int, 41 void __user *, size_t *, loff_t *); 42 extern int proc_dointvec(struct ctl_table *, int, 43 void __user *, size_t *, loff_t *); 44 extern int proc_dointvec_minmax(struct ctl_table *, int, 45 void __user *, size_t *, loff_t *); 46 extern int proc_dointvec_jiffies(struct ctl_table *, int, 47 void __user *, size_t *, loff_t *); 48 extern int proc_dointvec_userhz_jiffies(struct ctl_table *, int, 49 void __user *, size_t *, loff_t *); 50 extern int proc_dointvec_ms_jiffies(struct ctl_table *, int, 51 void __user *, size_t *, loff_t *); 52 extern int proc_doulongvec_minmax(struct ctl_table *, int, 53 void __user *, size_t *, loff_t *); 54 extern int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int, 55 void __user *, size_t *, loff_t *); 56 extern int proc_do_large_bitmap(struct ctl_table *, int, 57 void __user *, size_t *, loff_t *); 58 59 /* 60 * Register a set of sysctl names by calling register_sysctl_table 61 * with an initialised array of struct ctl_table's. An entry with 62 * NULL procname terminates the table. table->de will be 63 * set up by the registration and need not be initialised in advance. 64 * 65 * sysctl names can be mirrored automatically under /proc/sys. The 66 * procname supplied controls /proc naming. 67 * 68 * The table's mode will be honoured both for sys_sysctl(2) and 69 * proc-fs access. 70 * 71 * Leaf nodes in the sysctl tree will be represented by a single file 72 * under /proc; non-leaf nodes will be represented by directories. A 73 * null procname disables /proc mirroring at this node. 74 * 75 * sysctl(2) can automatically manage read and write requests through 76 * the sysctl table. The data and maxlen fields of the ctl_table 77 * struct enable minimal validation of the values being written to be 78 * performed, and the mode field allows minimal authentication. 79 * 80 * There must be a proc_handler routine for any terminal nodes 81 * mirrored under /proc/sys (non-terminals are handled by a built-in 82 * directory handler). Several default handlers are available to 83 * cover common cases. 84 */ 85 86 /* Support for userspace poll() to watch for changes */ 87 struct ctl_table_poll { 88 atomic_t event; 89 wait_queue_head_t wait; 90 }; 91 92 static inline void *proc_sys_poll_event(struct ctl_table_poll *poll) 93 { 94 return (void *)(unsigned long)atomic_read(&poll->event); 95 } 96 97 #define __CTL_TABLE_POLL_INITIALIZER(name) { \ 98 .event = ATOMIC_INIT(0), \ 99 .wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.wait) } 100 101 #define DEFINE_CTL_TABLE_POLL(name) \ 102 struct ctl_table_poll name = __CTL_TABLE_POLL_INITIALIZER(name) 103 104 /* A sysctl table is an array of struct ctl_table: */ 105 struct ctl_table 106 { 107 const char *procname; /* Text ID for /proc/sys, or zero */ 108 void *data; 109 int maxlen; 110 umode_t mode; 111 struct ctl_table *child; /* Deprecated */ 112 proc_handler *proc_handler; /* Callback for text formatting */ 113 struct ctl_table_poll *poll; 114 void *extra1; 115 void *extra2; 116 }; 117 118 struct ctl_node { 119 struct rb_node node; 120 struct ctl_table_header *header; 121 }; 122 123 /* struct ctl_table_header is used to maintain dynamic lists of 124 struct ctl_table trees. */ 125 struct ctl_table_header 126 { 127 union { 128 struct { 129 struct ctl_table *ctl_table; 130 int used; 131 int count; 132 int nreg; 133 }; 134 struct rcu_head rcu; 135 }; 136 struct completion *unregistering; 137 struct ctl_table *ctl_table_arg; 138 struct ctl_table_root *root; 139 struct ctl_table_set *set; 140 struct ctl_dir *parent; 141 struct ctl_node *node; 142 }; 143 144 struct ctl_dir { 145 /* Header must be at the start of ctl_dir */ 146 struct ctl_table_header header; 147 struct rb_root root; 148 }; 149 150 struct ctl_table_set { 151 int (*is_seen)(struct ctl_table_set *); 152 struct ctl_dir dir; 153 }; 154 155 struct ctl_table_root { 156 struct ctl_table_set default_set; 157 struct ctl_table_set *(*lookup)(struct ctl_table_root *root, 158 struct nsproxy *namespaces); 159 int (*permissions)(struct ctl_table_header *head, struct ctl_table *table); 160 }; 161 162 /* struct ctl_path describes where in the hierarchy a table is added */ 163 struct ctl_path { 164 const char *procname; 165 }; 166 167 #ifdef CONFIG_SYSCTL 168 169 void proc_sys_poll_notify(struct ctl_table_poll *poll); 170 171 extern void setup_sysctl_set(struct ctl_table_set *p, 172 struct ctl_table_root *root, 173 int (*is_seen)(struct ctl_table_set *)); 174 extern void retire_sysctl_set(struct ctl_table_set *set); 175 176 void register_sysctl_root(struct ctl_table_root *root); 177 struct ctl_table_header *__register_sysctl_table( 178 struct ctl_table_set *set, 179 const char *path, struct ctl_table *table); 180 struct ctl_table_header *__register_sysctl_paths( 181 struct ctl_table_set *set, 182 const struct ctl_path *path, struct ctl_table *table); 183 struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table); 184 struct ctl_table_header *register_sysctl_table(struct ctl_table * table); 185 struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path, 186 struct ctl_table *table); 187 188 void unregister_sysctl_table(struct ctl_table_header * table); 189 190 extern int sysctl_init(void); 191 192 extern struct ctl_table sysctl_mount_point[]; 193 194 #else /* CONFIG_SYSCTL */ 195 static inline struct ctl_table_header *register_sysctl_table(struct ctl_table * table) 196 { 197 return NULL; 198 } 199 200 static inline struct ctl_table_header *register_sysctl_paths( 201 const struct ctl_path *path, struct ctl_table *table) 202 { 203 return NULL; 204 } 205 206 static inline void unregister_sysctl_table(struct ctl_table_header * table) 207 { 208 } 209 210 static inline void setup_sysctl_set(struct ctl_table_set *p, 211 struct ctl_table_root *root, 212 int (*is_seen)(struct ctl_table_set *)) 213 { 214 } 215 216 #endif /* CONFIG_SYSCTL */ 217 218 int sysctl_max_threads(struct ctl_table *table, int write, 219 void __user *buffer, size_t *lenp, loff_t *ppos); 220 221 #endif /* _LINUX_SYSCTL_H */ 222