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 typedef int proc_handler (struct ctl_table *ctl, int write, 41 void __user *buffer, size_t *lenp, loff_t *ppos); 42 43 extern int proc_dostring(struct ctl_table *, int, 44 void __user *, size_t *, loff_t *); 45 extern int proc_dointvec(struct ctl_table *, int, 46 void __user *, size_t *, loff_t *); 47 extern int proc_douintvec(struct ctl_table *, int, 48 void __user *, size_t *, loff_t *); 49 extern int proc_dointvec_minmax(struct ctl_table *, int, 50 void __user *, size_t *, loff_t *); 51 extern int proc_douintvec_minmax(struct ctl_table *table, int write, 52 void __user *buffer, size_t *lenp, 53 loff_t *ppos); 54 extern int proc_dointvec_jiffies(struct ctl_table *, int, 55 void __user *, size_t *, loff_t *); 56 extern int proc_dointvec_userhz_jiffies(struct ctl_table *, int, 57 void __user *, size_t *, loff_t *); 58 extern int proc_dointvec_ms_jiffies(struct ctl_table *, int, 59 void __user *, size_t *, loff_t *); 60 extern int proc_doulongvec_minmax(struct ctl_table *, int, 61 void __user *, size_t *, loff_t *); 62 extern int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int, 63 void __user *, size_t *, loff_t *); 64 extern int proc_do_large_bitmap(struct ctl_table *, int, 65 void __user *, size_t *, loff_t *); 66 67 /* 68 * Register a set of sysctl names by calling register_sysctl_table 69 * with an initialised array of struct ctl_table's. An entry with 70 * NULL procname terminates the table. table->de will be 71 * set up by the registration and need not be initialised in advance. 72 * 73 * sysctl names can be mirrored automatically under /proc/sys. The 74 * procname supplied controls /proc naming. 75 * 76 * The table's mode will be honoured both for sys_sysctl(2) and 77 * proc-fs access. 78 * 79 * Leaf nodes in the sysctl tree will be represented by a single file 80 * under /proc; non-leaf nodes will be represented by directories. A 81 * null procname disables /proc mirroring at this node. 82 * 83 * sysctl(2) can automatically manage read and write requests through 84 * the sysctl table. The data and maxlen fields of the ctl_table 85 * struct enable minimal validation of the values being written to be 86 * performed, and the mode field allows minimal authentication. 87 * 88 * There must be a proc_handler routine for any terminal nodes 89 * mirrored under /proc/sys (non-terminals are handled by a built-in 90 * directory handler). Several default handlers are available to 91 * cover common cases. 92 */ 93 94 /* Support for userspace poll() to watch for changes */ 95 struct ctl_table_poll { 96 atomic_t event; 97 wait_queue_head_t wait; 98 }; 99 100 static inline void *proc_sys_poll_event(struct ctl_table_poll *poll) 101 { 102 return (void *)(unsigned long)atomic_read(&poll->event); 103 } 104 105 #define __CTL_TABLE_POLL_INITIALIZER(name) { \ 106 .event = ATOMIC_INIT(0), \ 107 .wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.wait) } 108 109 #define DEFINE_CTL_TABLE_POLL(name) \ 110 struct ctl_table_poll name = __CTL_TABLE_POLL_INITIALIZER(name) 111 112 /* A sysctl table is an array of struct ctl_table: */ 113 struct ctl_table 114 { 115 const char *procname; /* Text ID for /proc/sys, or zero */ 116 void *data; 117 int maxlen; 118 umode_t mode; 119 struct ctl_table *child; /* Deprecated */ 120 proc_handler *proc_handler; /* Callback for text formatting */ 121 struct ctl_table_poll *poll; 122 void *extra1; 123 void *extra2; 124 } __randomize_layout; 125 126 struct ctl_node { 127 struct rb_node node; 128 struct ctl_table_header *header; 129 }; 130 131 /* struct ctl_table_header is used to maintain dynamic lists of 132 struct ctl_table trees. */ 133 struct ctl_table_header 134 { 135 union { 136 struct { 137 struct ctl_table *ctl_table; 138 int used; 139 int count; 140 int nreg; 141 }; 142 struct rcu_head rcu; 143 }; 144 struct completion *unregistering; 145 struct ctl_table *ctl_table_arg; 146 struct ctl_table_root *root; 147 struct ctl_table_set *set; 148 struct ctl_dir *parent; 149 struct ctl_node *node; 150 struct hlist_head inodes; /* head for proc_inode->sysctl_inodes */ 151 }; 152 153 struct ctl_dir { 154 /* Header must be at the start of ctl_dir */ 155 struct ctl_table_header header; 156 struct rb_root root; 157 }; 158 159 struct ctl_table_set { 160 int (*is_seen)(struct ctl_table_set *); 161 struct ctl_dir dir; 162 }; 163 164 struct ctl_table_root { 165 struct ctl_table_set default_set; 166 struct ctl_table_set *(*lookup)(struct ctl_table_root *root); 167 void (*set_ownership)(struct ctl_table_header *head, 168 struct ctl_table *table, 169 kuid_t *uid, kgid_t *gid); 170 int (*permissions)(struct ctl_table_header *head, struct ctl_table *table); 171 }; 172 173 /* struct ctl_path describes where in the hierarchy a table is added */ 174 struct ctl_path { 175 const char *procname; 176 }; 177 178 #ifdef CONFIG_SYSCTL 179 180 void proc_sys_poll_notify(struct ctl_table_poll *poll); 181 182 extern void setup_sysctl_set(struct ctl_table_set *p, 183 struct ctl_table_root *root, 184 int (*is_seen)(struct ctl_table_set *)); 185 extern void retire_sysctl_set(struct ctl_table_set *set); 186 187 struct ctl_table_header *__register_sysctl_table( 188 struct ctl_table_set *set, 189 const char *path, struct ctl_table *table); 190 struct ctl_table_header *__register_sysctl_paths( 191 struct ctl_table_set *set, 192 const struct ctl_path *path, struct ctl_table *table); 193 struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table); 194 struct ctl_table_header *register_sysctl_table(struct ctl_table * table); 195 struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path, 196 struct ctl_table *table); 197 198 void unregister_sysctl_table(struct ctl_table_header * table); 199 200 extern int sysctl_init(void); 201 202 extern struct ctl_table sysctl_mount_point[]; 203 204 #else /* CONFIG_SYSCTL */ 205 static inline struct ctl_table_header *register_sysctl_table(struct ctl_table * table) 206 { 207 return NULL; 208 } 209 210 static inline struct ctl_table_header *register_sysctl_paths( 211 const struct ctl_path *path, struct ctl_table *table) 212 { 213 return NULL; 214 } 215 216 static inline struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table) 217 { 218 return NULL; 219 } 220 221 static inline void unregister_sysctl_table(struct ctl_table_header * table) 222 { 223 } 224 225 static inline void setup_sysctl_set(struct ctl_table_set *p, 226 struct ctl_table_root *root, 227 int (*is_seen)(struct ctl_table_set *)) 228 { 229 } 230 231 #endif /* CONFIG_SYSCTL */ 232 233 int sysctl_max_threads(struct ctl_table *table, int write, 234 void __user *buffer, size_t *lenp, loff_t *ppos); 235 236 #endif /* _LINUX_SYSCTL_H */ 237