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 const char *procname; /* Text ID for /proc/sys, or zero */ 125 void *data; 126 int maxlen; 127 umode_t mode; 128 struct ctl_table *child; /* Deprecated */ 129 proc_handler *proc_handler; /* Callback for text formatting */ 130 struct ctl_table_poll *poll; 131 void *extra1; 132 void *extra2; 133 } __randomize_layout; 134 135 struct ctl_node { 136 struct rb_node node; 137 struct ctl_table_header *header; 138 }; 139 140 /* struct ctl_table_header is used to maintain dynamic lists of 141 struct ctl_table trees. */ 142 struct ctl_table_header { 143 union { 144 struct { 145 struct ctl_table *ctl_table; 146 int used; 147 int count; 148 int nreg; 149 }; 150 struct rcu_head rcu; 151 }; 152 struct completion *unregistering; 153 struct ctl_table *ctl_table_arg; 154 struct ctl_table_root *root; 155 struct ctl_table_set *set; 156 struct ctl_dir *parent; 157 struct ctl_node *node; 158 struct hlist_head inodes; /* head for proc_inode->sysctl_inodes */ 159 }; 160 161 struct ctl_dir { 162 /* Header must be at the start of ctl_dir */ 163 struct ctl_table_header header; 164 struct rb_root root; 165 }; 166 167 struct ctl_table_set { 168 int (*is_seen)(struct ctl_table_set *); 169 struct ctl_dir dir; 170 }; 171 172 struct ctl_table_root { 173 struct ctl_table_set default_set; 174 struct ctl_table_set *(*lookup)(struct ctl_table_root *root); 175 void (*set_ownership)(struct ctl_table_header *head, 176 struct ctl_table *table, 177 kuid_t *uid, kgid_t *gid); 178 int (*permissions)(struct ctl_table_header *head, struct ctl_table *table); 179 }; 180 181 /* struct ctl_path describes where in the hierarchy a table is added */ 182 struct ctl_path { 183 const char *procname; 184 }; 185 186 #ifdef CONFIG_SYSCTL 187 188 void proc_sys_poll_notify(struct ctl_table_poll *poll); 189 190 extern void setup_sysctl_set(struct ctl_table_set *p, 191 struct ctl_table_root *root, 192 int (*is_seen)(struct ctl_table_set *)); 193 extern void retire_sysctl_set(struct ctl_table_set *set); 194 195 struct ctl_table_header *__register_sysctl_table( 196 struct ctl_table_set *set, 197 const char *path, struct ctl_table *table); 198 struct ctl_table_header *__register_sysctl_paths( 199 struct ctl_table_set *set, 200 const struct ctl_path *path, struct ctl_table *table); 201 struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table); 202 struct ctl_table_header *register_sysctl_table(struct ctl_table * table); 203 struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path, 204 struct ctl_table *table); 205 206 void unregister_sysctl_table(struct ctl_table_header * table); 207 208 extern int sysctl_init(void); 209 210 extern struct ctl_table sysctl_mount_point[]; 211 212 #else /* CONFIG_SYSCTL */ 213 static inline struct ctl_table_header *register_sysctl_table(struct ctl_table * table) 214 { 215 return NULL; 216 } 217 218 static inline struct ctl_table_header *register_sysctl_paths( 219 const struct ctl_path *path, struct ctl_table *table) 220 { 221 return NULL; 222 } 223 224 static inline struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table) 225 { 226 return NULL; 227 } 228 229 static inline void unregister_sysctl_table(struct ctl_table_header * table) 230 { 231 } 232 233 static inline void setup_sysctl_set(struct ctl_table_set *p, 234 struct ctl_table_root *root, 235 int (*is_seen)(struct ctl_table_set *)) 236 { 237 } 238 239 #endif /* CONFIG_SYSCTL */ 240 241 int sysctl_max_threads(struct ctl_table *table, int write, 242 void __user *buffer, size_t *lenp, loff_t *ppos); 243 244 #endif /* _LINUX_SYSCTL_H */ 245