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(const struct ctl_table *ctl, int write, void *buffer, 65 size_t *lenp, loff_t *ppos); 66 67 int proc_dostring(const struct ctl_table *, int, void *, size_t *, loff_t *); 68 int proc_dobool(const struct ctl_table *table, int write, void *buffer, 69 size_t *lenp, loff_t *ppos); 70 int proc_dointvec(const struct ctl_table *, int, void *, size_t *, loff_t *); 71 int proc_douintvec(const struct ctl_table *, int, void *, size_t *, loff_t *); 72 int proc_dointvec_minmax(const struct ctl_table *, int, void *, size_t *, loff_t *); 73 int proc_douintvec_minmax(const struct ctl_table *table, int write, void *buffer, 74 size_t *lenp, loff_t *ppos); 75 int proc_dou8vec_minmax(const struct ctl_table *table, int write, void *buffer, 76 size_t *lenp, loff_t *ppos); 77 int proc_dointvec_jiffies(const struct ctl_table *, int, void *, size_t *, loff_t *); 78 int proc_dointvec_ms_jiffies_minmax(const struct ctl_table *table, int write, 79 void *buffer, size_t *lenp, loff_t *ppos); 80 int proc_dointvec_userhz_jiffies(const struct ctl_table *, int, void *, size_t *, 81 loff_t *); 82 int proc_dointvec_ms_jiffies(const struct ctl_table *, int, void *, size_t *, 83 loff_t *); 84 int proc_doulongvec_minmax(const struct ctl_table *, int, void *, size_t *, loff_t *); 85 int proc_doulongvec_ms_jiffies_minmax(const struct ctl_table *table, int, void *, 86 size_t *, loff_t *); 87 int proc_do_large_bitmap(const struct ctl_table *, int, void *, size_t *, loff_t *); 88 int proc_do_static_key(const 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. 94 * 95 * sysctl names can be mirrored automatically under /proc/sys. The 96 * procname supplied controls /proc naming. 97 * 98 * The table's mode will be honoured for proc-fs access. 99 * 100 * Leaf nodes in the sysctl tree will be represented by a single file 101 * under /proc; non-leaf nodes will be represented by directories. A 102 * null procname disables /proc mirroring at this node. 103 * 104 * The data and maxlen fields of the ctl_table 105 * struct enable minimal validation of the values being written to be 106 * performed, and the mode field allows minimal authentication. 107 * 108 * There must be a proc_handler routine for any terminal nodes 109 * mirrored under /proc/sys (non-terminals are handled by a built-in 110 * directory handler). Several default handlers are available to 111 * cover common cases. 112 */ 113 114 /* Support for userspace poll() to watch for changes */ 115 struct ctl_table_poll { 116 atomic_t event; 117 wait_queue_head_t wait; 118 }; 119 120 static inline void *proc_sys_poll_event(struct ctl_table_poll *poll) 121 { 122 return (void *)(unsigned long)atomic_read(&poll->event); 123 } 124 125 #define __CTL_TABLE_POLL_INITIALIZER(name) { \ 126 .event = ATOMIC_INIT(0), \ 127 .wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.wait) } 128 129 #define DEFINE_CTL_TABLE_POLL(name) \ 130 struct ctl_table_poll name = __CTL_TABLE_POLL_INITIALIZER(name) 131 132 /* A sysctl table is an array of struct ctl_table: */ 133 struct ctl_table { 134 const char *procname; /* Text ID for /proc/sys */ 135 void *data; 136 int maxlen; 137 umode_t mode; 138 proc_handler *proc_handler; /* Callback for text formatting */ 139 struct ctl_table_poll *poll; 140 void *extra1; 141 void *extra2; 142 } __randomize_layout; 143 144 struct ctl_node { 145 struct rb_node node; 146 struct ctl_table_header *header; 147 }; 148 149 /** 150 * struct ctl_table_header - maintains dynamic lists of struct ctl_table trees 151 * @ctl_table: pointer to the first element in ctl_table array 152 * @ctl_table_size: number of elements pointed by @ctl_table 153 * @used: The entry will never be touched when equal to 0. 154 * @count: Upped every time something is added to @inodes and downed every time 155 * something is removed from inodes 156 * @nreg: When nreg drops to 0 the ctl_table_header will be unregistered. 157 * @rcu: Delays the freeing of the inode. Introduced with "unfuck proc_sysctl ->d_compare()" 158 * 159 */ 160 struct ctl_table_header { 161 union { 162 struct { 163 const struct ctl_table *ctl_table; 164 int ctl_table_size; 165 int used; 166 int count; 167 int nreg; 168 }; 169 struct rcu_head rcu; 170 }; 171 struct completion *unregistering; 172 const struct ctl_table *ctl_table_arg; 173 struct ctl_table_root *root; 174 struct ctl_table_set *set; 175 struct ctl_dir *parent; 176 struct ctl_node *node; 177 struct hlist_head inodes; /* head for proc_inode->sysctl_inodes */ 178 /** 179 * enum type - Enumeration to differentiate between ctl target types 180 * @SYSCTL_TABLE_TYPE_DEFAULT: ctl target with no special considerations 181 * @SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY: Used to identify a permanently 182 * empty directory target to serve 183 * as mount point. 184 */ 185 enum { 186 SYSCTL_TABLE_TYPE_DEFAULT, 187 SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY, 188 } type; 189 }; 190 191 struct ctl_dir { 192 /* Header must be at the start of ctl_dir */ 193 struct ctl_table_header header; 194 struct rb_root root; 195 }; 196 197 struct ctl_table_set { 198 int (*is_seen)(struct ctl_table_set *); 199 struct ctl_dir dir; 200 }; 201 202 struct ctl_table_root { 203 struct ctl_table_set default_set; 204 struct ctl_table_set *(*lookup)(struct ctl_table_root *root); 205 void (*set_ownership)(struct ctl_table_header *head, 206 kuid_t *uid, kgid_t *gid); 207 int (*permissions)(struct ctl_table_header *head, const struct ctl_table *table); 208 }; 209 210 #define register_sysctl(path, table) \ 211 register_sysctl_sz(path, table, ARRAY_SIZE(table)) 212 213 #ifdef CONFIG_SYSCTL 214 215 void proc_sys_poll_notify(struct ctl_table_poll *poll); 216 217 extern void setup_sysctl_set(struct ctl_table_set *p, 218 struct ctl_table_root *root, 219 int (*is_seen)(struct ctl_table_set *)); 220 extern void retire_sysctl_set(struct ctl_table_set *set); 221 222 struct ctl_table_header *__register_sysctl_table( 223 struct ctl_table_set *set, 224 const char *path, const struct ctl_table *table, size_t table_size); 225 struct ctl_table_header *register_sysctl_sz(const char *path, const struct ctl_table *table, 226 size_t table_size); 227 void unregister_sysctl_table(struct ctl_table_header * table); 228 229 extern int sysctl_init_bases(void); 230 extern void __register_sysctl_init(const char *path, const struct ctl_table *table, 231 const char *table_name, size_t table_size); 232 #define register_sysctl_init(path, table) \ 233 __register_sysctl_init(path, table, #table, ARRAY_SIZE(table)) 234 extern struct ctl_table_header *register_sysctl_mount_point(const char *path); 235 236 void do_sysctl_args(void); 237 bool sysctl_is_alias(char *param); 238 int do_proc_douintvec(const struct ctl_table *table, int write, 239 void *buffer, size_t *lenp, loff_t *ppos, 240 int (*conv)(unsigned long *lvalp, 241 unsigned int *valp, 242 int write, void *data), 243 void *data); 244 245 extern int pwrsw_enabled; 246 extern int unaligned_enabled; 247 extern int unaligned_dump_stack; 248 extern int no_unaligned_warning; 249 250 #else /* CONFIG_SYSCTL */ 251 252 static inline void register_sysctl_init(const char *path, const struct ctl_table *table) 253 { 254 } 255 256 static inline struct ctl_table_header *register_sysctl_mount_point(const char *path) 257 { 258 return NULL; 259 } 260 261 static inline struct ctl_table_header *register_sysctl_sz(const char *path, 262 const struct ctl_table *table, 263 size_t table_size) 264 { 265 return NULL; 266 } 267 268 static inline void unregister_sysctl_table(struct ctl_table_header * table) 269 { 270 } 271 272 static inline void setup_sysctl_set(struct ctl_table_set *p, 273 struct ctl_table_root *root, 274 int (*is_seen)(struct ctl_table_set *)) 275 { 276 } 277 278 static inline void do_sysctl_args(void) 279 { 280 } 281 282 static inline bool sysctl_is_alias(char *param) 283 { 284 return false; 285 } 286 #endif /* CONFIG_SYSCTL */ 287 288 int sysctl_max_threads(const struct ctl_table *table, int write, void *buffer, 289 size_t *lenp, loff_t *ppos); 290 291 #endif /* _LINUX_SYSCTL_H */ 292