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, void *buffer, 48 size_t *lenp, loff_t *ppos); 49 50 int proc_dostring(struct ctl_table *, int, void *, size_t *, loff_t *); 51 int proc_dointvec(struct ctl_table *, int, void *, size_t *, loff_t *); 52 int proc_douintvec(struct ctl_table *, int, void *, size_t *, loff_t *); 53 int proc_dointvec_minmax(struct ctl_table *, int, void *, size_t *, loff_t *); 54 int proc_douintvec_minmax(struct ctl_table *table, int write, void *buffer, 55 size_t *lenp, loff_t *ppos); 56 int proc_dointvec_jiffies(struct ctl_table *, int, void *, size_t *, loff_t *); 57 int proc_dointvec_userhz_jiffies(struct ctl_table *, int, void *, size_t *, 58 loff_t *); 59 int proc_dointvec_ms_jiffies(struct ctl_table *, int, void *, size_t *, 60 loff_t *); 61 int proc_doulongvec_minmax(struct ctl_table *, int, void *, size_t *, loff_t *); 62 int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int, void *, 63 size_t *, loff_t *); 64 int proc_do_large_bitmap(struct ctl_table *, int, void *, size_t *, loff_t *); 65 int proc_do_static_key(struct ctl_table *table, int write, void *buffer, 66 size_t *lenp, loff_t *ppos); 67 68 /* 69 * Register a set of sysctl names by calling register_sysctl_table 70 * with an initialised array of struct ctl_table's. An entry with 71 * NULL procname terminates the table. table->de will be 72 * set up by the registration and need not be initialised in advance. 73 * 74 * sysctl names can be mirrored automatically under /proc/sys. The 75 * procname supplied controls /proc naming. 76 * 77 * The table's mode will be honoured both for sys_sysctl(2) and 78 * proc-fs access. 79 * 80 * Leaf nodes in the sysctl tree will be represented by a single file 81 * under /proc; non-leaf nodes will be represented by directories. A 82 * null procname disables /proc mirroring at this node. 83 * 84 * sysctl(2) can automatically manage read and write requests through 85 * the sysctl table. The data and maxlen fields of the ctl_table 86 * struct enable minimal validation of the values being written to be 87 * performed, and the mode field allows minimal authentication. 88 * 89 * There must be a proc_handler routine for any terminal nodes 90 * mirrored under /proc/sys (non-terminals are handled by a built-in 91 * directory handler). Several default handlers are available to 92 * cover common cases. 93 */ 94 95 /* Support for userspace poll() to watch for changes */ 96 struct ctl_table_poll { 97 atomic_t event; 98 wait_queue_head_t wait; 99 }; 100 101 static inline void *proc_sys_poll_event(struct ctl_table_poll *poll) 102 { 103 return (void *)(unsigned long)atomic_read(&poll->event); 104 } 105 106 #define __CTL_TABLE_POLL_INITIALIZER(name) { \ 107 .event = ATOMIC_INIT(0), \ 108 .wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.wait) } 109 110 #define DEFINE_CTL_TABLE_POLL(name) \ 111 struct ctl_table_poll name = __CTL_TABLE_POLL_INITIALIZER(name) 112 113 /* A sysctl table is an array of struct ctl_table: */ 114 struct ctl_table { 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 union { 135 struct { 136 struct ctl_table *ctl_table; 137 int used; 138 int count; 139 int nreg; 140 }; 141 struct rcu_head rcu; 142 }; 143 struct completion *unregistering; 144 struct ctl_table *ctl_table_arg; 145 struct ctl_table_root *root; 146 struct ctl_table_set *set; 147 struct ctl_dir *parent; 148 struct ctl_node *node; 149 struct hlist_head inodes; /* head for proc_inode->sysctl_inodes */ 150 }; 151 152 struct ctl_dir { 153 /* Header must be at the start of ctl_dir */ 154 struct ctl_table_header header; 155 struct rb_root root; 156 }; 157 158 struct ctl_table_set { 159 int (*is_seen)(struct ctl_table_set *); 160 struct ctl_dir dir; 161 }; 162 163 struct ctl_table_root { 164 struct ctl_table_set default_set; 165 struct ctl_table_set *(*lookup)(struct ctl_table_root *root); 166 void (*set_ownership)(struct ctl_table_header *head, 167 struct ctl_table *table, 168 kuid_t *uid, kgid_t *gid); 169 int (*permissions)(struct ctl_table_header *head, struct ctl_table *table); 170 }; 171 172 /* struct ctl_path describes where in the hierarchy a table is added */ 173 struct ctl_path { 174 const char *procname; 175 }; 176 177 #ifdef CONFIG_SYSCTL 178 179 void proc_sys_poll_notify(struct ctl_table_poll *poll); 180 181 extern void setup_sysctl_set(struct ctl_table_set *p, 182 struct ctl_table_root *root, 183 int (*is_seen)(struct ctl_table_set *)); 184 extern void retire_sysctl_set(struct ctl_table_set *set); 185 186 struct ctl_table_header *__register_sysctl_table( 187 struct ctl_table_set *set, 188 const char *path, struct ctl_table *table); 189 struct ctl_table_header *__register_sysctl_paths( 190 struct ctl_table_set *set, 191 const struct ctl_path *path, struct ctl_table *table); 192 struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table); 193 struct ctl_table_header *register_sysctl_table(struct ctl_table * table); 194 struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path, 195 struct ctl_table *table); 196 197 void unregister_sysctl_table(struct ctl_table_header * table); 198 199 extern int sysctl_init(void); 200 void do_sysctl_args(void); 201 202 extern int pwrsw_enabled; 203 extern int unaligned_enabled; 204 extern int unaligned_dump_stack; 205 extern int no_unaligned_warning; 206 207 extern struct ctl_table sysctl_mount_point[]; 208 extern struct ctl_table random_table[]; 209 extern struct ctl_table firmware_config_table[]; 210 extern struct ctl_table epoll_table[]; 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 static inline void do_sysctl_args(void) 240 { 241 } 242 #endif /* CONFIG_SYSCTL */ 243 244 int sysctl_max_threads(struct ctl_table *table, int write, void *buffer, 245 size_t *lenp, loff_t *ppos); 246 247 #endif /* _LINUX_SYSCTL_H */ 248