| 1 | |
| 2 | *
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| 3 | * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
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| 4 | * Written by David Howells ([email protected])
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| 5 | *
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| 6 | * This program is free software; you can redistribute it and/or
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| 7 | * modify it under the terms of the GNU General Public Licence
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| 8 | * as published by the Free Software Foundation; either version
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| 9 | * 2 of the Licence, or (at your option) any later version.
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| 10 |
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| 11 |
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| 12 | #ifndef _LINUX_CRED_H
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| 13 | #define _LINUX_CRED_H
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| 14 |
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| 15 | #include <linux/capability.h>
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| 16 | #include <linux/init.h>
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| 17 | #include <linux/key.h>
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| 18 | #include <linux/selinux.h>
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| 19 | #include <linux/atomic.h>
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| 20 | #include <linux/uidgid.h>
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| 21 |
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| 22 | struct user_struct;
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| 23 | struct cred;
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| 24 | struct inode;
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| 25 |
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| 26 | |
| 27 | * COW Supplementary groups list
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| 28 |
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| 29 | #define NGROUPS_SMALL 32
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| 30 | #define NGROUPS_PER_BLOCK ((unsigned int)(PAGE_SIZE / sizeof(kgid_t)))
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| 31 |
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| 32 | struct group_info {
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| 33 | atomic_t usage;
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| 34 | int ngroups;
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| 35 | int nblocks;
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| 36 | kgid_t small_block[NGROUPS_SMALL];
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| 37 | kgid_t *blocks[0];
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| 38 | };
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| 39 |
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| 40 | |
| 41 | * get_group_info - Get a reference to a group info structure
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| 42 | * @group_info: The group info to reference
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| 43 | *
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| 44 | * This gets a reference to a set of supplementary groups.
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| 45 | *
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| 46 | * If the caller is accessing a task's credentials, they must hold the RCU read
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| 47 | * lock when reading.
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| 48 |
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| 49 | static inline struct group_info *get_group_info(struct group_info *gi)
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| 50 | {
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| 51 | atomic_inc(&gi->usage);
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| 52 | return gi;
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| 53 | }
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| 54 |
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| 55 | |
| 56 | * put_group_info - Release a reference to a group info structure
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| 57 | * @group_info: The group info to release
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| 58 |
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| 59 | #define put_group_info(group_info) \
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| 60 | do { \
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| 61 | if (atomic_dec_and_test(&(group_info)->usage)) \
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| 62 | groups_free(group_info); \
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| 63 | } while (0)
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| 64 |
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| 65 | extern struct group_info *groups_alloc(int);
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| 66 | extern struct group_info init_groups;
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| 67 | extern void groups_free(struct group_info *);
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| 68 | extern int set_current_groups(struct group_info *);
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| 69 | extern void set_groups(struct cred *, struct group_info *);
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| 70 | extern int groups_search(const struct group_info *, kgid_t);
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| 71 |
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| 72 |
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| 73 | #define GROUP_AT(gi, i) \
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| 74 | ((gi)->blocks[(i) / NGROUPS_PER_BLOCK][(i) % NGROUPS_PER_BLOCK])
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| 75 |
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| 76 | extern int in_group_p(kgid_t);
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| 77 | extern int in_egroup_p(kgid_t);
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| 78 |
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| 79 | |
| 80 | * The security context of a task
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| 81 | *
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| 82 | * The parts of the context break down into two categories:
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| 83 | *
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| 84 | * (1) The objective context of a task. These parts are used when some other
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| 85 | * task is attempting to affect this one.
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| 86 | *
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| 87 | * (2) The subjective context. These details are used when the task is acting
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| 88 | * upon another object, be that a file, a task, a key or whatever.
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| 89 | *
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| 90 | * Note that some members of this structure belong to both categories - the
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| 91 | * LSM security pointer for instance.
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| 92 | *
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| 93 | * A task has two security pointers. task->real_cred points to the objective
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| 94 | * context that defines that task's actual details. The objective part of this
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| 95 | * context is used whenever that task is acted upon.
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| 96 | *
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| 97 | * task->cred points to the subjective context that defines the details of how
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| 98 | * that task is going to act upon another object. This may be overridden
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| 99 | * temporarily to point to another security context, but normally points to the
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| 100 | * same context as task->real_cred.
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| 101 |
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| 102 | struct cred {
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| 103 | atomic_t usage;
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| 104 | #ifdef CONFIG_DEBUG_CREDENTIALS
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| 105 | atomic_t subscribers;
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| 106 | void *put_addr;
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| 107 | unsigned magic;
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| 108 | #define CRED_MAGIC 0x43736564
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| 109 | #define CRED_MAGIC_DEAD 0x44656144
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| 110 | #endif
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| 111 | kuid_t uid;
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| 112 | kgid_t gid;
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| 113 | kuid_t suid;
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| 114 | kgid_t sgid;
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| 115 | kuid_t euid;
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| 116 | kgid_t egid;
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| 117 | kuid_t fsuid;
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| 118 | kgid_t fsgid;
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| 119 | unsigned securebits;
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| 120 | kernel_cap_t cap_inheritable;
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| 121 | kernel_cap_t cap_permitted;
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| 122 | kernel_cap_t cap_effective;
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| 123 | kernel_cap_t cap_bset;
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| 124 | #ifdef CONFIG_KEYS
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| 125 | unsigned char jit_keyring; |
| 126 | * keys to
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| 127 | struct key __rcu *session_keyring;
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| 128 | struct key *process_keyring;
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| 129 | struct key *thread_keyring;
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| 130 | struct key *request_key_auth;
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| 131 | #endif
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| 132 | #ifdef CONFIG_SECURITY
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| 133 | void *security;
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| 134 | #endif
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| 135 | struct user_struct *user;
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| 136 | struct user_namespace *user_ns;
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| 137 | struct group_info *group_info;
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| 138 | struct rcu_head rcu;
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| 139 | };
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| 140 |
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| 141 | extern void __put_cred(struct cred *);
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| 142 | extern void exit_creds(struct task_struct *);
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| 143 | extern int copy_creds(struct task_struct *, unsigned long);
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| 144 | extern const struct cred *get_task_cred(struct task_struct *);
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| 145 | extern struct cred *cred_alloc_blank(void);
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| 146 | extern struct cred *prepare_creds(void);
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| 147 | extern struct cred *prepare_exec_creds(void);
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| 148 | extern int commit_creds(struct cred *);
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| 149 | extern void abort_creds(struct cred *);
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| 150 | extern const struct cred *override_creds(const struct cred *);
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| 151 | extern void revert_creds(const struct cred *);
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| 152 | extern struct cred *prepare_kernel_cred(struct task_struct *);
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| 153 | extern int change_create_files_as(struct cred *, struct inode *);
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| 154 | extern int set_security_override(struct cred *, u32);
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| 155 | extern int set_security_override_from_ctx(struct cred *, const char *);
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| 156 | extern int set_create_files_as(struct cred *, struct inode *);
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| 157 | extern void __init cred_init(void);
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| 158 |
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| 159 | |
| 160 | * check for validity of credentials
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| 161 |
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| 162 | #ifdef CONFIG_DEBUG_CREDENTIALS
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| 163 | extern void __invalid_creds(const struct cred *, const char *, unsigned);
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| 164 | extern void __validate_process_creds(struct task_struct *,
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| 165 | const char *, unsigned);
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| 166 |
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| 167 | extern bool creds_are_invalid(const struct cred *cred);
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| 168 |
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| 169 | static inline void __validate_creds(const struct cred *cred,
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| 170 | const char *file, unsigned line)
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| 171 | {
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| 172 | if (unlikely(creds_are_invalid(cred)))
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| 173 | __invalid_creds(cred, file, line);
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| 174 | }
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| 175 |
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| 176 | #define validate_creds(cred) \
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| 177 | do { \
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| 178 | __validate_creds((cred), __FILE__, __LINE__); \
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| 179 | } while(0)
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| 180 |
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| 181 | #define validate_process_creds() \
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| 182 | do { \
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| 183 | __validate_process_creds(current, __FILE__, __LINE__); \
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| 184 | } while(0)
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| 185 |
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| 186 | extern void validate_creds_for_do_exit(struct task_struct *);
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| 187 | #else
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| 188 | static inline void validate_creds(const struct cred *cred)
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| 189 | {
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| 190 | }
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| 191 | static inline void validate_creds_for_do_exit(struct task_struct *tsk)
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| 192 | {
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| 193 | }
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| 194 | static inline void validate_process_creds(void)
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| 195 | {
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| 196 | }
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| 197 | #endif
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| 198 |
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| 199 | |
| 200 | * get_new_cred - Get a reference on a new set of credentials
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| 201 | * @cred: The new credentials to reference
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| 202 | *
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| 203 | * Get a reference on the specified set of new credentials. The caller must
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| 204 | * release the reference.
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| 205 |
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| 206 | static inline struct cred *get_new_cred(struct cred *cred)
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| 207 | {
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| 208 | atomic_inc(&cred->usage);
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| 209 | return cred;
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| 210 | }
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| 211 |
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| 212 | |
| 213 | * get_cred - Get a reference on a set of credentials
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| 214 | * @cred: The credentials to reference
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| 215 | *
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| 216 | * Get a reference on the specified set of credentials. The caller must
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| 217 | * release the reference.
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| 218 | *
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| 219 | * This is used to deal with a committed set of credentials. Although the
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| 220 | * pointer is const, this will temporarily discard the const and increment the
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| 221 | * usage count. The purpose of this is to attempt to catch at compile time the
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| 222 | * accidental alteration of a set of credentials that should be considered
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| 223 | * immutable.
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| 224 |
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| 225 | static inline const struct cred *get_cred(const struct cred *cred)
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| 226 | {
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| 227 | struct cred *nonconst_cred = (struct cred *) cred;
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| 228 | validate_creds(cred);
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| 229 | return get_new_cred(nonconst_cred);
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| 230 | }
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| 231 |
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| 232 | |
| 233 | * put_cred - Release a reference to a set of credentials
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| 234 | * @cred: The credentials to release
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| 235 | *
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| 236 | * Release a reference to a set of credentials, deleting them when the last ref
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| 237 | * is released.
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| 238 | *
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| 239 | * This takes a const pointer to a set of credentials because the credentials
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| 240 | * on task_struct are attached by const pointers to prevent accidental
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| 241 | * alteration of otherwise immutable credential sets.
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| 242 |
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| 243 | static inline void put_cred(const struct cred *_cred)
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| 244 | {
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| 245 | struct cred *cred = (struct cred *) _cred;
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| 246 |
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| 247 | validate_creds(cred);
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| 248 | if (atomic_dec_and_test(&(cred)->usage))
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| 249 | __put_cred(cred);
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| 250 | }
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| 251 |
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| 252 | |
| 253 | * current_cred - Access the current task's subjective credentials
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| 254 | *
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| 255 | * Access the subjective credentials of the current task. RCU-safe,
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| 256 | * since nobody else can modify it.
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| 257 |
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| 258 | #define current_cred() \
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| 259 | rcu_dereference_protected(current->cred, 1)
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| 260 |
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| 261 | |
| 262 | * __task_cred - Access a task's objective credentials
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| 263 | * @task: The task to query
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| 264 | *
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| 265 | * Access the objective credentials of a task. The caller must hold the RCU
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| 266 | * readlock.
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| 267 | *
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| 268 | * The result of this function should not be passed directly to get_cred();
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| 269 | * rather get_task_cred() should be used instead.
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| 270 |
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| 271 | #define __task_cred(task) \
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| 272 | rcu_dereference((task)->real_cred)
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| 273 |
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| 274 | |
| 275 | * get_current_cred - Get the current task's subjective credentials
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| 276 | *
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| 277 | * Get the subjective credentials of the current task, pinning them so that
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| 278 | * they can't go away. Accessing the current task's credentials directly is
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| 279 | * not permitted.
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| 280 |
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| 281 | #define get_current_cred() \
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| 282 | (get_cred(current_cred()))
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| 283 |
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| 284 | |
| 285 | * get_current_user - Get the current task's user_struct
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| 286 | *
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| 287 | * Get the user record of the current task, pinning it so that it can't go
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| 288 | * away.
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| 289 |
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| 290 | #define get_current_user() \
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| 291 | ({ \
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| 292 | struct user_struct *__u; \
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| 293 | const struct cred *__cred; \
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| 294 | __cred = current_cred(); \
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| 295 | __u = get_uid(__cred->user); \
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| 296 | __u; \
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| 297 | })
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| 298 |
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| 299 | |
| 300 | * get_current_groups - Get the current task's supplementary group list
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| 301 | *
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| 302 | * Get the supplementary group list of the current task, pinning it so that it
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| 303 | * can't go away.
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| 304 |
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| 305 | #define get_current_groups() \
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| 306 | ({ \
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| 307 | struct group_info *__groups; \
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| 308 | const struct cred *__cred; \
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| 309 | __cred = current_cred(); \
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| 310 | __groups = get_group_info(__cred->group_info); \
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| 311 | __groups; \
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| 312 | })
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| 313 |
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| 314 | #define task_cred_xxx(task, xxx) \
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| 315 | ({ \
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| 316 | __typeof__(((struct cred *)NULL)->xxx) ___val; \
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| 317 | rcu_read_lock(); \
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| 318 | ___val = __task_cred((task))->xxx; \
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| 319 | rcu_read_unlock(); \
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| 320 | ___val; \
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| 321 | })
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| 322 |
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| 323 | #define task_uid(task) (task_cred_xxx((task), uid))
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| 324 | #define task_euid(task) (task_cred_xxx((task), euid))
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| 325 |
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| 326 | #define current_cred_xxx(xxx) \
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| 327 | ({ \
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| 328 | current_cred()->xxx; \
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| 329 | })
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| 330 |
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| 331 | #define current_uid() (current_cred_xxx(uid))
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| 332 | #define current_gid() (current_cred_xxx(gid))
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| 333 | #define current_euid() (current_cred_xxx(euid))
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| 334 | #define current_egid() (current_cred_xxx(egid))
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| 335 | #define current_suid() (current_cred_xxx(suid))
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| 336 | #define current_sgid() (current_cred_xxx(sgid))
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| 337 | #define current_fsuid() (current_cred_xxx(fsuid))
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| 338 | #define current_fsgid() (current_cred_xxx(fsgid))
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| 339 | #define current_cap() (current_cred_xxx(cap_effective))
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| 340 | #define current_user() (current_cred_xxx(user))
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| 341 | #define current_security() (current_cred_xxx(security))
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| 342 |
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| 343 | extern struct user_namespace init_user_ns;
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| 344 | #ifdef CONFIG_USER_NS
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| 345 | #define current_user_ns() (current_cred_xxx(user_ns))
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| 346 | #else
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| 347 | #define current_user_ns() (&init_user_ns)
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| 348 | #endif
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| 349 |
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| 350 |
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| 351 | #define current_uid_gid(_uid, _gid) \
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| 352 | do { \
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| 353 | const struct cred *__cred; \
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| 354 | __cred = current_cred(); \
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| 355 | *(_uid) = __cred->uid; \
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| 356 | *(_gid) = __cred->gid; \
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| 357 | } while(0)
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| 358 |
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| 359 | #define current_euid_egid(_euid, _egid) \
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| 360 | do { \
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| 361 | const struct cred *__cred; \
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| 362 | __cred = current_cred(); \
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| 363 | *(_euid) = __cred->euid; \
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| 364 | *(_egid) = __cred->egid; \
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| 365 | } while(0)
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| 366 |
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| 367 | #define current_fsuid_fsgid(_fsuid, _fsgid) \
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| 368 | do { \
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| 369 | const struct cred *__cred; \
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| 370 | __cred = current_cred(); \
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| 371 | *(_fsuid) = __cred->fsuid; \
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| 372 | *(_fsgid) = __cred->fsgid; \
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| 373 | } while(0)
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| 374 |
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| 375 | #endif
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