398 lines
13 KiB
C
398 lines
13 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* sysctl.h: General linux system control interface
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*
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* Begun 24 March 1995, Stephen Tweedie
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*
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****************************************************************
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****************************************************************
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**
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** WARNING:
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** The values in this file are exported to user space via
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** the sysctl() binary interface. Do *NOT* change the
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** numbering of any existing values here, and do not change
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** any numbers within any one set of values. If you have to
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** redefine an existing interface, use a new number for it.
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** The kernel will then return -ENOTDIR to any application using
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** the old binary interface.
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**
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****************************************************************
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****************************************************************
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*/
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#ifndef _LINUX_SYSCTL_H
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#define _LINUX_SYSCTL_H
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#include <linux/list.h>
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#include <linux/rcupdate.h>
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#include <linux/wait.h>
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#include <linux/rbtree.h>
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#include <linux/uidgid.h>
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#include <uapi/linux/sysctl.h>
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/* For the /proc/sys support */
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struct completion;
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struct ctl_table;
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struct nsproxy;
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struct ctl_table_root;
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struct ctl_table_header;
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struct ctl_dir;
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/* Keep the same order as in fs/proc/proc_sysctl.c */
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#define SYSCTL_ZERO ((void *)&sysctl_vals[0])
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#define SYSCTL_ONE ((void *)&sysctl_vals[1])
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#define SYSCTL_TWO ((void *)&sysctl_vals[2])
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#define SYSCTL_THREE ((void *)&sysctl_vals[3])
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#define SYSCTL_FOUR ((void *)&sysctl_vals[4])
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#define SYSCTL_ONE_HUNDRED ((void *)&sysctl_vals[5])
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#define SYSCTL_TWO_HUNDRED ((void *)&sysctl_vals[6])
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#define SYSCTL_ONE_THOUSAND ((void *)&sysctl_vals[7])
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#define SYSCTL_THREE_THOUSAND ((void *)&sysctl_vals[8])
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#define SYSCTL_INT_MAX ((void *)&sysctl_vals[9])
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/* this is needed for the proc_dointvec_minmax for [fs_]overflow UID and GID */
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#define SYSCTL_MAXOLDUID ((void *)&sysctl_vals[10])
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#define SYSCTL_NEG_ONE ((void *)&sysctl_vals[11])
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extern const int sysctl_vals[];
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#define SYSCTL_LONG_ZERO ((void *)&sysctl_long_vals[0])
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#define SYSCTL_LONG_ONE ((void *)&sysctl_long_vals[1])
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#define SYSCTL_LONG_MAX ((void *)&sysctl_long_vals[2])
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#define SYSCTL_CONV_IDENTITY(val) (val)
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/**
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*
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* "dir" originates from read_iter (dir = 0) or write_iter (dir = 1)
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* in the file_operations struct at proc/proc_sysctl.c. Its value means
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* one of two things for sysctl:
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* 1. SYSCTL_USER_TO_KERN(dir) Writing to an internal kernel variable from user
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* space (dir > 0)
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* 2. SYSCTL_KERN_TO_USER(dir) Writing to a user space buffer from a kernel
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* variable (dir == 0).
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*/
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#define SYSCTL_USER_TO_KERN(dir) (!!(dir))
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#define SYSCTL_KERN_TO_USER(dir) (!dir)
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#define SYSCTL_USER_TO_KERN_INT_CONV(name, u_ptr_op) \
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int sysctl_user_to_kern_int_conv##name(const bool *negp, \
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const unsigned long *u_ptr,\
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int *k_ptr) \
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{ \
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unsigned long u = u_ptr_op(*u_ptr); \
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if (*negp) { \
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if (u > (unsigned long) INT_MAX + 1) \
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return -EINVAL; \
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WRITE_ONCE(*k_ptr, -u); \
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} else { \
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if (u > (unsigned long) INT_MAX) \
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return -EINVAL; \
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WRITE_ONCE(*k_ptr, u); \
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} \
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return 0; \
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}
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#define SYSCTL_KERN_TO_USER_INT_CONV(name, k_ptr_op) \
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int sysctl_kern_to_user_int_conv##name(bool *negp, \
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unsigned long *u_ptr, \
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const int *k_ptr) \
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{ \
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int val = READ_ONCE(*k_ptr); \
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if (val < 0) { \
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*negp = true; \
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*u_ptr = -k_ptr_op((unsigned long)val); \
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} else { \
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*negp = false; \
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*u_ptr = k_ptr_op((unsigned long)val); \
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} \
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return 0; \
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}
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/**
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* To range check on a converted value, use a temp k_ptr
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* When checking range, value should be within (tbl->extra1, tbl->extra2)
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*/
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#define SYSCTL_INT_CONV_CUSTOM(name, user_to_kern, kern_to_user, \
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k_ptr_range_check) \
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int do_proc_int_conv##name(bool *negp, unsigned long *u_ptr, int *k_ptr,\
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int dir, const struct ctl_table *tbl) \
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{ \
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if (SYSCTL_KERN_TO_USER(dir)) \
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return kern_to_user(negp, u_ptr, k_ptr); \
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\
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if (k_ptr_range_check) { \
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int tmp_k, ret; \
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if (!tbl) \
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return -EINVAL; \
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ret = user_to_kern(negp, u_ptr, &tmp_k); \
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if (ret) \
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return ret; \
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if ((tbl->extra1 && *(int *)tbl->extra1 > tmp_k) || \
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(tbl->extra2 && *(int *)tbl->extra2 < tmp_k)) \
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return -EINVAL; \
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WRITE_ONCE(*k_ptr, tmp_k); \
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} else \
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return user_to_kern(negp, u_ptr, k_ptr); \
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return 0; \
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}
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#define SYSCTL_USER_TO_KERN_UINT_CONV(name, u_ptr_op) \
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int sysctl_user_to_kern_uint_conv##name(const unsigned long *u_ptr,\
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unsigned int *k_ptr) \
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{ \
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unsigned long u = u_ptr_op(*u_ptr); \
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if (u > UINT_MAX) \
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return -EINVAL; \
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WRITE_ONCE(*k_ptr, u); \
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return 0; \
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}
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#define SYSCTL_UINT_CONV_CUSTOM(name, user_to_kern, kern_to_user, \
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k_ptr_range_check) \
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int do_proc_uint_conv##name(unsigned long *u_ptr, unsigned int *k_ptr, \
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int dir, const struct ctl_table *tbl) \
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{ \
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if (SYSCTL_KERN_TO_USER(dir)) \
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return kern_to_user(u_ptr, k_ptr); \
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\
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if (k_ptr_range_check) { \
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unsigned int tmp_k; \
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int ret; \
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if (!tbl) \
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return -EINVAL; \
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ret = user_to_kern(u_ptr, &tmp_k); \
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if (ret) \
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return ret; \
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if ((tbl->extra1 && \
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*(unsigned int *)tbl->extra1 > tmp_k) || \
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(tbl->extra2 && \
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*(unsigned int *)tbl->extra2 < tmp_k)) \
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return -ERANGE; \
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WRITE_ONCE(*k_ptr, tmp_k); \
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} else \
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return user_to_kern(u_ptr, k_ptr); \
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return 0; \
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}
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extern const unsigned long sysctl_long_vals[];
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typedef int proc_handler(const struct ctl_table *ctl, int write, void *buffer,
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size_t *lenp, loff_t *ppos);
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int proc_dostring(const struct ctl_table *, int, void *, size_t *, loff_t *);
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int proc_dobool(const struct ctl_table *table, int write, void *buffer,
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size_t *lenp, loff_t *ppos);
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int proc_dointvec(const struct ctl_table *, int, void *, size_t *, loff_t *);
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int proc_dointvec_minmax(const struct ctl_table *table, int dir, void *buffer,
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size_t *lenp, loff_t *ppos);
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int proc_dointvec_conv(const struct ctl_table *table, int dir, void *buffer,
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size_t *lenp, loff_t *ppos,
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int (*conv)(bool *negp, unsigned long *u_ptr, int *k_ptr,
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int dir, const struct ctl_table *table));
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int proc_douintvec(const struct ctl_table *, int, void *, size_t *, loff_t *);
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int proc_douintvec_minmax(const struct ctl_table *table, int write, void *buffer,
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size_t *lenp, loff_t *ppos);
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int proc_douintvec_conv(const struct ctl_table *table, int write, void *buffer,
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size_t *lenp, loff_t *ppos,
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int (*conv)(unsigned long *lvalp, unsigned int *valp,
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int write, const struct ctl_table *table));
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int proc_dou8vec_minmax(const struct ctl_table *table, int write, void *buffer,
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size_t *lenp, loff_t *ppos);
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int proc_doulongvec_minmax(const struct ctl_table *, int, void *, size_t *, loff_t *);
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int proc_doulongvec_minmax_conv(const struct ctl_table *table, int dir,
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void *buffer, size_t *lenp, loff_t *ppos,
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unsigned long convmul, unsigned long convdiv);
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int proc_do_large_bitmap(const struct ctl_table *, int, void *, size_t *, loff_t *);
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int proc_do_static_key(const struct ctl_table *table, int write, void *buffer,
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size_t *lenp, loff_t *ppos);
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int sysctl_kern_to_user_uint_conv(unsigned long *u_ptr, const unsigned int *k_ptr);
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/*
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* Register a set of sysctl names by calling register_sysctl
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* with an initialised array of struct ctl_table's.
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*
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* sysctl names can be mirrored automatically under /proc/sys. The
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* procname supplied controls /proc naming.
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*
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* The table's mode will be honoured for proc-fs access.
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*
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* Leaf nodes in the sysctl tree will be represented by a single file
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* under /proc; non-leaf nodes will be represented by directories. A
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* null procname disables /proc mirroring at this node.
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*
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* The data and maxlen fields of the ctl_table
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* struct enable minimal validation of the values being written to be
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* performed, and the mode field allows minimal authentication.
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*
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* There must be a proc_handler routine for any terminal nodes
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* mirrored under /proc/sys (non-terminals are handled by a built-in
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* directory handler). Several default handlers are available to
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* cover common cases.
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*/
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/* Support for userspace poll() to watch for changes */
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struct ctl_table_poll {
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atomic_t event;
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wait_queue_head_t wait;
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};
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static inline void *proc_sys_poll_event(struct ctl_table_poll *poll)
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{
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return (void *)(unsigned long)atomic_read(&poll->event);
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}
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#define __CTL_TABLE_POLL_INITIALIZER(name) { \
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.event = ATOMIC_INIT(0), \
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.wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.wait) }
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#define DEFINE_CTL_TABLE_POLL(name) \
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struct ctl_table_poll name = __CTL_TABLE_POLL_INITIALIZER(name)
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/* A sysctl table is an array of struct ctl_table: */
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struct ctl_table {
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const char *procname; /* Text ID for /proc/sys */
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void *data;
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int maxlen;
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umode_t mode;
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proc_handler *proc_handler; /* Callback for text formatting */
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struct ctl_table_poll *poll;
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void *extra1;
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void *extra2;
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} __randomize_layout;
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struct ctl_node {
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struct rb_node node;
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struct ctl_table_header *header;
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};
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/**
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* struct ctl_table_header - maintains dynamic lists of struct ctl_table trees
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* @ctl_table: pointer to the first element in ctl_table array
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* @ctl_table_size: number of elements pointed by @ctl_table
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* @used: The entry will never be touched when equal to 0.
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* @count: Upped every time something is added to @inodes and downed every time
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* something is removed from inodes
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* @nreg: When nreg drops to 0 the ctl_table_header will be unregistered.
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* @rcu: Delays the freeing of the inode. Introduced with "unfuck proc_sysctl ->d_compare()"
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*
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* @type: Enumeration to differentiate between ctl target types
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* @type.SYSCTL_TABLE_TYPE_DEFAULT: ctl target with no special considerations
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* @type.SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY: Identifies a permanently empty dir
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* target to serve as a mount point
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*/
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struct ctl_table_header {
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union {
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struct {
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const struct ctl_table *ctl_table;
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int ctl_table_size;
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int used;
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int count;
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int nreg;
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};
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struct rcu_head rcu;
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};
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struct completion *unregistering;
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const struct ctl_table *ctl_table_arg;
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struct ctl_table_root *root;
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struct ctl_table_set *set;
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struct ctl_dir *parent;
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struct ctl_node *node;
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struct hlist_head inodes; /* head for proc_inode->sysctl_inodes */
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enum {
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SYSCTL_TABLE_TYPE_DEFAULT,
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SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY,
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} type;
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};
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struct ctl_dir {
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/* Header must be at the start of ctl_dir */
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struct ctl_table_header header;
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struct rb_root root;
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};
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struct ctl_table_set {
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int (*is_seen)(struct ctl_table_set *);
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struct ctl_dir dir;
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};
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struct ctl_table_root {
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struct ctl_table_set default_set;
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struct ctl_table_set *(*lookup)(struct ctl_table_root *root);
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void (*set_ownership)(struct ctl_table_header *head,
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kuid_t *uid, kgid_t *gid);
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int (*permissions)(struct ctl_table_header *head, const struct ctl_table *table);
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};
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#define register_sysctl(path, table) \
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register_sysctl_sz(path, table, ARRAY_SIZE(table))
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#ifdef CONFIG_SYSCTL
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void proc_sys_poll_notify(struct ctl_table_poll *poll);
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extern void setup_sysctl_set(struct ctl_table_set *p,
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struct ctl_table_root *root,
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int (*is_seen)(struct ctl_table_set *));
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extern void retire_sysctl_set(struct ctl_table_set *set);
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struct ctl_table_header *__register_sysctl_table(
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struct ctl_table_set *set,
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const char *path, const struct ctl_table *table, size_t table_size);
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struct ctl_table_header *register_sysctl_sz(const char *path, const struct ctl_table *table,
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size_t table_size);
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void unregister_sysctl_table(struct ctl_table_header * table);
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extern int sysctl_init_bases(void);
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extern void __register_sysctl_init(const char *path, const struct ctl_table *table,
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const char *table_name, size_t table_size);
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#define register_sysctl_init(path, table) \
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__register_sysctl_init(path, table, #table, ARRAY_SIZE(table))
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extern struct ctl_table_header *register_sysctl_mount_point(const char *path);
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void do_sysctl_args(void);
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bool sysctl_is_alias(char *param);
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extern int unaligned_enabled;
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extern int no_unaligned_warning;
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#else /* CONFIG_SYSCTL */
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static inline void register_sysctl_init(const char *path, const struct ctl_table *table)
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{
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}
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static inline struct ctl_table_header *register_sysctl_mount_point(const char *path)
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{
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return NULL;
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}
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static inline struct ctl_table_header *register_sysctl_sz(const char *path,
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const struct ctl_table *table,
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size_t table_size)
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{
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return NULL;
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}
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static inline void unregister_sysctl_table(struct ctl_table_header * table)
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{
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}
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static inline void setup_sysctl_set(struct ctl_table_set *p,
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struct ctl_table_root *root,
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int (*is_seen)(struct ctl_table_set *))
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{
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}
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static inline void do_sysctl_args(void)
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{
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}
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static inline bool sysctl_is_alias(char *param)
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{
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return false;
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}
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#endif /* CONFIG_SYSCTL */
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#endif /* _LINUX_SYSCTL_H */
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