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_TWO ((void *)&sysctl_vals[2]) 44 #define SYSCTL_THREE ((void *)&sysctl_vals[3]) 45 #define SYSCTL_FOUR ((void *)&sysctl_vals[4]) 46 #define SYSCTL_ONE_HUNDRED ((void *)&sysctl_vals[5]) 47 #define SYSCTL_TWO_HUNDRED ((void *)&sysctl_vals[6]) 48 #define SYSCTL_ONE_THOUSAND ((void *)&sysctl_vals[7]) 49 #define SYSCTL_THREE_THOUSAND ((void *)&sysctl_vals[8]) 50 #define SYSCTL_INT_MAX ((void *)&sysctl_vals[9]) 51 52 /* this is needed for the proc_dointvec_minmax for [fs_]overflow UID and GID */ 53 #define SYSCTL_MAXOLDUID ((void *)&sysctl_vals[10]) 54 #define SYSCTL_NEG_ONE ((void *)&sysctl_vals[11]) 55 56 extern const int sysctl_vals[]; 57 58 #define SYSCTL_LONG_ZERO ((void *)&sysctl_long_vals[0]) 59 #define SYSCTL_LONG_ONE ((void *)&sysctl_long_vals[1]) 60 #define SYSCTL_LONG_MAX ((void *)&sysctl_long_vals[2]) 61 62 extern const unsigned long sysctl_long_vals[]; 63 64 typedef int proc_handler(struct ctl_table *ctl, int write, void *buffer, 65 size_t *lenp, loff_t *ppos); 66 67 int proc_dostring(struct ctl_table *, int, void *, size_t *, loff_t *); 68 int proc_dobool(struct ctl_table *table, int write, void *buffer, 69 size_t *lenp, loff_t *ppos); 70 int proc_dointvec(struct ctl_table *, int, void *, size_t *, loff_t *); 71 int proc_douintvec(struct ctl_table *, int, void *, size_t *, loff_t *); 72 int proc_dointvec_minmax(struct ctl_table *, int, void *, size_t *, loff_t *); 73 int proc_douintvec_minmax(struct ctl_table *table, int write, void *buffer, 74 size_t *lenp, loff_t *ppos); 75 int proc_dou8vec_minmax(struct ctl_table *table, int write, void *buffer, 76 size_t *lenp, loff_t *ppos); 77 int proc_dointvec_jiffies(struct ctl_table *, int, void *, size_t *, loff_t *); 78 int proc_dointvec_ms_jiffies_minmax(struct ctl_table *table, int write, 79 void *buffer, size_t *lenp, loff_t *ppos); 80 int proc_dointvec_userhz_jiffies(struct ctl_table *, int, void *, size_t *, 81 loff_t *); 82 int proc_dointvec_ms_jiffies(struct ctl_table *, int, void *, size_t *, 83 loff_t *); 84 int proc_doulongvec_minmax(struct ctl_table *, int, void *, size_t *, loff_t *); 85 int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int, void *, 86 size_t *, loff_t *); 87 int proc_do_large_bitmap(struct ctl_table *, int, void *, size_t *, loff_t *); 88 int proc_do_static_key(struct ctl_table *table, int write, void *buffer, 89 size_t *lenp, loff_t *ppos); 90 91 /* 92 * Register a set of sysctl names by calling register_sysctl 93 * with an initialised array of struct ctl_table's. An entry with 94 * NULL procname terminates the table. table->de will be 95 * set up by the registration and need not be initialised in advance. 96 * 97 * sysctl names can be mirrored automatically under /proc/sys. The 98 * procname supplied controls /proc naming. 99 * 100 * The table's mode will be honoured for proc-fs access. 101 * 102 * Leaf nodes in the sysctl tree will be represented by a single file 103 * under /proc; non-leaf nodes will be represented by directories. A 104 * null procname disables /proc mirroring at this node. 105 * 106 * The data and maxlen fields of the ctl_table 107 * struct enable minimal validation of the values being written to be 108 * performed, and the mode field allows minimal authentication. 109 * 110 * There must be a proc_handler routine for any terminal nodes 111 * mirrored under /proc/sys (non-terminals are handled by a built-in 112 * directory handler). Several default handlers are available to 113 * cover common cases. 114 */ 115 116 /* Support for userspace poll() to watch for changes */ 117 struct ctl_table_poll { 118 atomic_t event; 119 wait_queue_head_t wait; 120 }; 121 122 static inline void *proc_sys_poll_event(struct ctl_table_poll *poll) 123 { 124 return (void *)(unsigned long)atomic_read(&poll->event); 125 } 126 127 #define __CTL_TABLE_POLL_INITIALIZER(name) { \ 128 .event = ATOMIC_INIT(0), \ 129 .wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.wait) } 130 131 #define DEFINE_CTL_TABLE_POLL(name) \ 132 struct ctl_table_poll name = __CTL_TABLE_POLL_INITIALIZER(name) 133 134 /* A sysctl table is an array of struct ctl_table: */ 135 struct ctl_table { 136 const char *procname; /* Text ID for /proc/sys, or zero */ 137 void *data; 138 int maxlen; 139 umode_t mode; 140 /** 141 * enum type - Enumeration to differentiate between ctl target types 142 * @SYSCTL_TABLE_TYPE_DEFAULT: ctl target with no special considerations 143 * @SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY: Used to identify a permanently 144 * empty directory target to serve 145 * as mount point. 146 */ 147 enum { 148 SYSCTL_TABLE_TYPE_DEFAULT, 149 SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY 150 } type; 151 proc_handler *proc_handler; /* Callback for text formatting */ 152 struct ctl_table_poll *poll; 153 void *extra1; 154 void *extra2; 155 } __randomize_layout; 156 157 struct ctl_node { 158 struct rb_node node; 159 struct ctl_table_header *header; 160 }; 161 162 /** 163 * struct ctl_table_header - maintains dynamic lists of struct ctl_table trees 164 * @ctl_table: pointer to the first element in ctl_table array 165 * @ctl_table_size: number of elements pointed by @ctl_table 166 * @used: The entry will never be touched when equal to 0. 167 * @count: Upped every time something is added to @inodes and downed every time 168 * something is removed from inodes 169 * @nreg: When nreg drops to 0 the ctl_table_header will be unregistered. 170 * @rcu: Delays the freeing of the inode. Introduced with "unfuck proc_sysctl ->d_compare()" 171 * 172 */ 173 struct ctl_table_header { 174 union { 175 struct { 176 struct ctl_table *ctl_table; 177 int ctl_table_size; 178 int used; 179 int count; 180 int nreg; 181 }; 182 struct rcu_head rcu; 183 }; 184 struct completion *unregistering; 185 struct ctl_table *ctl_table_arg; 186 struct ctl_table_root *root; 187 struct ctl_table_set *set; 188 struct ctl_dir *parent; 189 struct ctl_node *node; 190 struct hlist_head inodes; /* head for proc_inode->sysctl_inodes */ 191 }; 192 193 struct ctl_dir { 194 /* Header must be at the start of ctl_dir */ 195 struct ctl_table_header header; 196 struct rb_root root; 197 }; 198 199 struct ctl_table_set { 200 int (*is_seen)(struct ctl_table_set *); 201 struct ctl_dir dir; 202 }; 203 204 struct ctl_table_root { 205 struct ctl_table_set default_set; 206 struct ctl_table_set *(*lookup)(struct ctl_table_root *root); 207 void (*set_ownership)(struct ctl_table_header *head, 208 struct ctl_table *table, 209 kuid_t *uid, kgid_t *gid); 210 int (*permissions)(struct ctl_table_header *head, struct ctl_table *table); 211 }; 212 213 /* struct ctl_path describes where in the hierarchy a table is added */ 214 struct ctl_path { 215 const char *procname; 216 }; 217 218 #define register_sysctl(path, table) \ 219 register_sysctl_sz(path, table, ARRAY_SIZE(table)) 220 221 #ifdef CONFIG_SYSCTL 222 223 void proc_sys_poll_notify(struct ctl_table_poll *poll); 224 225 extern void setup_sysctl_set(struct ctl_table_set *p, 226 struct ctl_table_root *root, 227 int (*is_seen)(struct ctl_table_set *)); 228 extern void retire_sysctl_set(struct ctl_table_set *set); 229 230 struct ctl_table_header *__register_sysctl_table( 231 struct ctl_table_set *set, 232 const char *path, struct ctl_table *table, size_t table_size); 233 struct ctl_table_header *register_sysctl_sz(const char *path, struct ctl_table *table, 234 size_t table_size); 235 void unregister_sysctl_table(struct ctl_table_header * table); 236 237 extern int sysctl_init_bases(void); 238 extern void __register_sysctl_init(const char *path, struct ctl_table *table, 239 const char *table_name, size_t table_size); 240 #define register_sysctl_init(path, table) \ 241 __register_sysctl_init(path, table, #table, ARRAY_SIZE(table)) 242 extern struct ctl_table_header *register_sysctl_mount_point(const char *path); 243 244 void do_sysctl_args(void); 245 int do_proc_douintvec(struct ctl_table *table, int write, 246 void *buffer, size_t *lenp, loff_t *ppos, 247 int (*conv)(unsigned long *lvalp, 248 unsigned int *valp, 249 int write, void *data), 250 void *data); 251 252 extern int pwrsw_enabled; 253 extern int unaligned_enabled; 254 extern int unaligned_dump_stack; 255 extern int no_unaligned_warning; 256 257 #define SYSCTL_PERM_EMPTY_DIR (1 << 0) 258 259 #else /* CONFIG_SYSCTL */ 260 261 static inline void register_sysctl_init(const char *path, struct ctl_table *table) 262 { 263 } 264 265 static inline struct ctl_table_header *register_sysctl_mount_point(const char *path) 266 { 267 return NULL; 268 } 269 270 static inline struct ctl_table_header *register_sysctl_sz(const char *path, 271 struct ctl_table *table, 272 size_t table_size) 273 { 274 return NULL; 275 } 276 277 static inline void unregister_sysctl_table(struct ctl_table_header * table) 278 { 279 } 280 281 static inline void setup_sysctl_set(struct ctl_table_set *p, 282 struct ctl_table_root *root, 283 int (*is_seen)(struct ctl_table_set *)) 284 { 285 } 286 287 static inline void do_sysctl_args(void) 288 { 289 } 290 #endif /* CONFIG_SYSCTL */ 291 292 int sysctl_max_threads(struct ctl_table *table, int write, void *buffer, 293 size_t *lenp, loff_t *ppos); 294 295 #endif /* _LINUX_SYSCTL_H */ 296