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_dopipe_max_size(struct ctl_table *table, int write, 55 void __user *buffer, size_t *lenp, 56 loff_t *ppos); 57 extern int proc_dointvec_jiffies(struct ctl_table *, int, 58 void __user *, size_t *, loff_t *); 59 extern int proc_dointvec_userhz_jiffies(struct ctl_table *, int, 60 void __user *, size_t *, loff_t *); 61 extern int proc_dointvec_ms_jiffies(struct ctl_table *, int, 62 void __user *, size_t *, loff_t *); 63 extern int proc_doulongvec_minmax(struct ctl_table *, int, 64 void __user *, size_t *, loff_t *); 65 extern int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int, 66 void __user *, size_t *, loff_t *); 67 extern int proc_do_large_bitmap(struct ctl_table *, int, 68 void __user *, size_t *, loff_t *); 69 70 /* 71 * Register a set of sysctl names by calling register_sysctl_table 72 * with an initialised array of struct ctl_table's. An entry with 73 * NULL procname terminates the table. table->de will be 74 * set up by the registration and need not be initialised in advance. 75 * 76 * sysctl names can be mirrored automatically under /proc/sys. The 77 * procname supplied controls /proc naming. 78 * 79 * The table's mode will be honoured both for sys_sysctl(2) and 80 * proc-fs access. 81 * 82 * Leaf nodes in the sysctl tree will be represented by a single file 83 * under /proc; non-leaf nodes will be represented by directories. A 84 * null procname disables /proc mirroring at this node. 85 * 86 * sysctl(2) can automatically manage read and write requests through 87 * the sysctl table. The data and maxlen fields of the ctl_table 88 * struct enable minimal validation of the values being written to be 89 * performed, and the mode field allows minimal authentication. 90 * 91 * There must be a proc_handler routine for any terminal nodes 92 * mirrored under /proc/sys (non-terminals are handled by a built-in 93 * directory handler). Several default handlers are available to 94 * cover common cases. 95 */ 96 97 /* Support for userspace poll() to watch for changes */ 98 struct ctl_table_poll { 99 atomic_t event; 100 wait_queue_head_t wait; 101 }; 102 103 static inline void *proc_sys_poll_event(struct ctl_table_poll *poll) 104 { 105 return (void *)(unsigned long)atomic_read(&poll->event); 106 } 107 108 #define __CTL_TABLE_POLL_INITIALIZER(name) { \ 109 .event = ATOMIC_INIT(0), \ 110 .wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.wait) } 111 112 #define DEFINE_CTL_TABLE_POLL(name) \ 113 struct ctl_table_poll name = __CTL_TABLE_POLL_INITIALIZER(name) 114 115 /* A sysctl table is an array of struct ctl_table: */ 116 struct ctl_table 117 { 118 const char *procname; /* Text ID for /proc/sys, or zero */ 119 void *data; 120 int maxlen; 121 umode_t mode; 122 struct ctl_table *child; /* Deprecated */ 123 proc_handler *proc_handler; /* Callback for text formatting */ 124 struct ctl_table_poll *poll; 125 void *extra1; 126 void *extra2; 127 } __randomize_layout; 128 129 struct ctl_node { 130 struct rb_node node; 131 struct ctl_table_header *header; 132 }; 133 134 /* struct ctl_table_header is used to maintain dynamic lists of 135 struct ctl_table trees. */ 136 struct ctl_table_header 137 { 138 union { 139 struct { 140 struct ctl_table *ctl_table; 141 int used; 142 int count; 143 int nreg; 144 }; 145 struct rcu_head rcu; 146 }; 147 struct completion *unregistering; 148 struct ctl_table *ctl_table_arg; 149 struct ctl_table_root *root; 150 struct ctl_table_set *set; 151 struct ctl_dir *parent; 152 struct ctl_node *node; 153 struct hlist_head inodes; /* head for proc_inode->sysctl_inodes */ 154 }; 155 156 struct ctl_dir { 157 /* Header must be at the start of ctl_dir */ 158 struct ctl_table_header header; 159 struct rb_root root; 160 }; 161 162 struct ctl_table_set { 163 int (*is_seen)(struct ctl_table_set *); 164 struct ctl_dir dir; 165 }; 166 167 struct ctl_table_root { 168 struct ctl_table_set default_set; 169 struct ctl_table_set *(*lookup)(struct ctl_table_root *root); 170 void (*set_ownership)(struct ctl_table_header *head, 171 struct ctl_table *table, 172 kuid_t *uid, kgid_t *gid); 173 int (*permissions)(struct ctl_table_header *head, struct ctl_table *table); 174 }; 175 176 /* struct ctl_path describes where in the hierarchy a table is added */ 177 struct ctl_path { 178 const char *procname; 179 }; 180 181 #ifdef CONFIG_SYSCTL 182 183 void proc_sys_poll_notify(struct ctl_table_poll *poll); 184 185 extern void setup_sysctl_set(struct ctl_table_set *p, 186 struct ctl_table_root *root, 187 int (*is_seen)(struct ctl_table_set *)); 188 extern void retire_sysctl_set(struct ctl_table_set *set); 189 190 struct ctl_table_header *__register_sysctl_table( 191 struct ctl_table_set *set, 192 const char *path, struct ctl_table *table); 193 struct ctl_table_header *__register_sysctl_paths( 194 struct ctl_table_set *set, 195 const struct ctl_path *path, struct ctl_table *table); 196 struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table); 197 struct ctl_table_header *register_sysctl_table(struct ctl_table * table); 198 struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path, 199 struct ctl_table *table); 200 201 void unregister_sysctl_table(struct ctl_table_header * table); 202 203 extern int sysctl_init(void); 204 205 extern struct ctl_table sysctl_mount_point[]; 206 207 #else /* CONFIG_SYSCTL */ 208 static inline struct ctl_table_header *register_sysctl_table(struct ctl_table * table) 209 { 210 return NULL; 211 } 212 213 static inline struct ctl_table_header *register_sysctl_paths( 214 const struct ctl_path *path, struct ctl_table *table) 215 { 216 return NULL; 217 } 218 219 static inline struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table) 220 { 221 return NULL; 222 } 223 224 static inline void unregister_sysctl_table(struct ctl_table_header * table) 225 { 226 } 227 228 static inline void setup_sysctl_set(struct ctl_table_set *p, 229 struct ctl_table_root *root, 230 int (*is_seen)(struct ctl_table_set *)) 231 { 232 } 233 234 #endif /* CONFIG_SYSCTL */ 235 236 int sysctl_max_threads(struct ctl_table *table, int write, 237 void __user *buffer, size_t *lenp, loff_t *ppos); 238 239 #endif /* _LINUX_SYSCTL_H */ 240