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 */ 33struct completion; 34struct ctl_table; 35struct nsproxy; 36struct ctl_table_root; 37struct ctl_table_header; 38struct 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 56extern 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 62extern const unsigned long sysctl_long_vals[]; 63 64typedef int proc_handler(struct ctl_table *ctl, int write, void *buffer, 65 size_t *lenp, loff_t *ppos); 66 67int proc_dostring(struct ctl_table *, int, void *, size_t *, loff_t *); 68int proc_dobool(struct ctl_table *table, int write, void *buffer, 69 size_t *lenp, loff_t *ppos); 70int proc_dointvec(struct ctl_table *, int, void *, size_t *, loff_t *); 71int proc_douintvec(struct ctl_table *, int, void *, size_t *, loff_t *); 72int proc_dointvec_minmax(struct ctl_table *, int, void *, size_t *, loff_t *); 73int proc_douintvec_minmax(struct ctl_table *table, int write, void *buffer, 74 size_t *lenp, loff_t *ppos); 75int proc_dou8vec_minmax(struct ctl_table *table, int write, void *buffer, 76 size_t *lenp, loff_t *ppos); 77int proc_dointvec_jiffies(struct ctl_table *, int, void *, size_t *, loff_t *); 78int proc_dointvec_ms_jiffies_minmax(struct ctl_table *table, int write, 79 void *buffer, size_t *lenp, loff_t *ppos); 80int proc_dointvec_userhz_jiffies(struct ctl_table *, int, void *, size_t *, 81 loff_t *); 82int proc_dointvec_ms_jiffies(struct ctl_table *, int, void *, size_t *, 83 loff_t *); 84int proc_doulongvec_minmax(struct ctl_table *, int, void *, size_t *, loff_t *); 85int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int, void *, 86 size_t *, loff_t *); 87int proc_do_large_bitmap(struct ctl_table *, int, void *, size_t *, loff_t *); 88int 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 */ 117struct ctl_table_poll { 118 atomic_t event; 119 wait_queue_head_t wait; 120}; 121 122static 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: */ 135struct ctl_table { 136 const char *procname; /* Text ID for /proc/sys, or zero */ 137 void *data; 138 int maxlen; 139 umode_t mode; 140 proc_handler *proc_handler; /* Callback for text formatting */ 141 struct ctl_table_poll *poll; 142 void *extra1; 143 void *extra2; 144} __randomize_layout; 145 146struct ctl_node { 147 struct rb_node node; 148 struct ctl_table_header *header; 149}; 150 151/** 152 * struct ctl_table_header - maintains dynamic lists of struct ctl_table trees 153 * @ctl_table: pointer to the first element in ctl_table array 154 * @ctl_table_size: number of elements pointed by @ctl_table 155 * @used: The entry will never be touched when equal to 0. 156 * @count: Upped every time something is added to @inodes and downed every time 157 * something is removed from inodes 158 * @nreg: When nreg drops to 0 the ctl_table_header will be unregistered. 159 * @rcu: Delays the freeing of the inode. Introduced with "unfuck proc_sysctl ->d_compare()" 160 * 161 */ 162struct ctl_table_header { 163 union { 164 struct { 165 struct ctl_table *ctl_table; 166 int ctl_table_size; 167 int used; 168 int count; 169 int nreg; 170 }; 171 struct rcu_head rcu; 172 }; 173 struct completion *unregistering; 174 const struct ctl_table *ctl_table_arg; 175 struct ctl_table_root *root; 176 struct ctl_table_set *set; 177 struct ctl_dir *parent; 178 struct ctl_node *node; 179 struct hlist_head inodes; /* head for proc_inode->sysctl_inodes */ 180 /** 181 * enum type - Enumeration to differentiate between ctl target types 182 * @SYSCTL_TABLE_TYPE_DEFAULT: ctl target with no special considerations 183 * @SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY: Used to identify a permanently 184 * empty directory target to serve 185 * as mount point. 186 */ 187 enum { 188 SYSCTL_TABLE_TYPE_DEFAULT, 189 SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY, 190 } type; 191}; 192 193struct 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 199struct ctl_table_set { 200 int (*is_seen)(struct ctl_table_set *); 201 struct ctl_dir dir; 202}; 203 204struct 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 kuid_t *uid, kgid_t *gid); 209 int (*permissions)(struct ctl_table_header *head, const struct ctl_table *table); 210}; 211 212#define register_sysctl(path, table) \ 213 register_sysctl_sz(path, table, ARRAY_SIZE(table)) 214 215#ifdef CONFIG_SYSCTL 216 217void proc_sys_poll_notify(struct ctl_table_poll *poll); 218 219extern void setup_sysctl_set(struct ctl_table_set *p, 220 struct ctl_table_root *root, 221 int (*is_seen)(struct ctl_table_set *)); 222extern void retire_sysctl_set(struct ctl_table_set *set); 223 224struct ctl_table_header *__register_sysctl_table( 225 struct ctl_table_set *set, 226 const char *path, struct ctl_table *table, size_t table_size); 227struct ctl_table_header *register_sysctl_sz(const char *path, struct ctl_table *table, 228 size_t table_size); 229void unregister_sysctl_table(struct ctl_table_header * table); 230 231extern int sysctl_init_bases(void); 232extern void __register_sysctl_init(const char *path, struct ctl_table *table, 233 const char *table_name, size_t table_size); 234#define register_sysctl_init(path, table) \ 235 __register_sysctl_init(path, table, #table, ARRAY_SIZE(table)) 236extern struct ctl_table_header *register_sysctl_mount_point(const char *path); 237 238void do_sysctl_args(void); 239bool sysctl_is_alias(char *param); 240int do_proc_douintvec(struct ctl_table *table, int write, 241 void *buffer, size_t *lenp, loff_t *ppos, 242 int (*conv)(unsigned long *lvalp, 243 unsigned int *valp, 244 int write, void *data), 245 void *data); 246 247extern int pwrsw_enabled; 248extern int unaligned_enabled; 249extern int unaligned_dump_stack; 250extern int no_unaligned_warning; 251 252#else /* CONFIG_SYSCTL */ 253 254static inline void register_sysctl_init(const char *path, struct ctl_table *table) 255{ 256} 257 258static inline struct ctl_table_header *register_sysctl_mount_point(const char *path) 259{ 260 return NULL; 261} 262 263static inline struct ctl_table_header *register_sysctl_sz(const char *path, 264 struct ctl_table *table, 265 size_t table_size) 266{ 267 return NULL; 268} 269 270static inline void unregister_sysctl_table(struct ctl_table_header * table) 271{ 272} 273 274static inline void setup_sysctl_set(struct ctl_table_set *p, 275 struct ctl_table_root *root, 276 int (*is_seen)(struct ctl_table_set *)) 277{ 278} 279 280static inline void do_sysctl_args(void) 281{ 282} 283 284static inline bool sysctl_is_alias(char *param) 285{ 286 return false; 287} 288#endif /* CONFIG_SYSCTL */ 289 290int sysctl_max_threads(struct ctl_table *table, int write, void *buffer, 291 size_t *lenp, loff_t *ppos); 292 293#endif /* _LINUX_SYSCTL_H */ 294