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   1 /* Credentials management
   2  *
   3  * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public Licence
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the Licence, or (at your option) any later version.
  10  */
  11
  12 #ifndef _LINUX_CRED_H
  13 #define _LINUX_CRED_H
  14
  15 #include <linux/capability.h>
  16 #include <linux/key.h>
  17 #include <asm/atomic.h>
  18
  19 struct user_struct;
  20 struct cred;
  21
  22 /*
  23  * COW Supplementary groups list
  24  */
  25 #define NGROUPS_SMALL           32
  26 #define NGROUPS_PER_BLOCK       ((unsigned int)(PAGE_SIZE / sizeof(gid_t)))
  27
  28 struct group_info {
  29         atomic_t        usage;
  30         int             ngroups;
  31         int             nblocks;
  32         gid_t           small_block[NGROUPS_SMALL];
  33         gid_t           *blocks[0];
  34 };
  35
  36 /**
  37  * get_group_info - Get a reference to a group info structure
  38  * @group_info: The group info to reference
  39  *
  40  * This must be called with the owning task locked (via task_lock()) when task
  41  * != current.  The reason being that the vast majority of callers are looking
  42  * at current->group_info, which can not be changed except by the current task.
  43  * Changing current->group_info requires the task lock, too.
  44  */
  45 #define get_group_info(group_info)              \
  46 do {                                            \
  47         atomic_inc(&(group_info)->usage);       \
  48 } while (0)
  49
  50 /**
  51  * put_group_info - Release a reference to a group info structure
  52  * @group_info: The group info to release
  53  */
  54 #define put_group_info(group_info)                      \
  55 do {                                                    \
  56         if (atomic_dec_and_test(&(group_info)->usage))  \
  57                 groups_free(group_info);                \
  58 } while (0)
  59
  60 extern struct group_info *groups_alloc(int);
  61 extern void groups_free(struct group_info *);
  62 extern int set_current_groups(struct group_info *);
  63 extern int set_groups(struct cred *, struct group_info *);
  64 extern int groups_search(struct group_info *, gid_t);
  65
  66 /* access the groups "array" with this macro */
  67 #define GROUP_AT(gi, i) \
  68         ((gi)->blocks[(i) / NGROUPS_PER_BLOCK][(i) % NGROUPS_PER_BLOCK])
  69
  70 extern int in_group_p(gid_t);
  71 extern int in_egroup_p(gid_t);
  72
  73 /*
  74  * The security context of a task
  75  *
  76  * The parts of the context break down into two categories:
  77  *
  78  *  (1) The objective context of a task.  These parts are used when some other
  79  *      task is attempting to affect this one.
  80  *
  81  *  (2) The subjective context.  These details are used when the task is acting
  82  *      upon another object, be that a file, a task, a key or whatever.
  83  *
  84  * Note that some members of this structure belong to both categories - the
  85  * LSM security pointer for instance.
  86  *
  87  * A task has two security pointers.  task->real_cred points to the objective
  88  * context that defines that task's actual details.  The objective part of this
  89  * context is used whenever that task is acted upon.
  90  *
  91  * task->cred points to the subjective context that defines the details of how
  92  * that task is going to act upon another object.  This may be overridden
  93  * temporarily to point to another security context, but normally points to the
  94  * same context as task->real_cred.
  95  */
  96 struct cred {
  97         atomic_t        usage;
  98         uid_t           uid;            /* real UID of the task */
  99         gid_t           gid;            /* real GID of the task */
 100         uid_t           suid;           /* saved UID of the task */
 101         gid_t           sgid;           /* saved GID of the task */
 102         uid_t           euid;           /* effective UID of the task */
 103         gid_t           egid;           /* effective GID of the task */
 104         uid_t           fsuid;          /* UID for VFS ops */
 105         gid_t           fsgid;          /* GID for VFS ops */
 106         unsigned        securebits;     /* SUID-less security management */
 107         kernel_cap_t    cap_inheritable; /* caps our children can inherit */
 108         kernel_cap_t    cap_permitted;  /* caps we're permitted */
 109         kernel_cap_t    cap_effective;  /* caps we can actually use */
 110         kernel_cap_t    cap_bset;       /* capability bounding set */
 111 #ifdef CONFIG_KEYS
 112         unsigned char   jit_keyring;    /* default keyring to attach requested
 113                                          * keys to */
 114         struct key      *thread_keyring; /* keyring private to this thread */
 115         struct key      *request_key_auth; /* assumed request_key authority */
 116 #endif
 117 #ifdef CONFIG_SECURITY
 118         void            *security;      /* subjective LSM security */
 119 #endif
 120         struct user_struct *user;       /* real user ID subscription */
 121         struct group_info *group_info;  /* supplementary groups for euid/fsgid */
 122         struct rcu_head rcu;            /* RCU deletion hook */
 123         spinlock_t      lock;           /* lock for pointer changes */
 124 };
 125
 126 #define get_current_user()      (get_uid(current->cred->user))
 127
 128 #define task_uid(task)          ((task)->cred->uid)
 129 #define task_gid(task)          ((task)->cred->gid)
 130 #define task_euid(task)         ((task)->cred->euid)
 131 #define task_egid(task)         ((task)->cred->egid)
 132
 133 #define current_uid()           (current->cred->uid)
 134 #define current_gid()           (current->cred->gid)
 135 #define current_euid()          (current->cred->euid)
 136 #define current_egid()          (current->cred->egid)
 137 #define current_suid()          (current->cred->suid)
 138 #define current_sgid()          (current->cred->sgid)
 139 #define current_fsuid()         (current->cred->fsuid)
 140 #define current_fsgid()         (current->cred->fsgid)
 141 #define current_cap()           (current->cred->cap_effective)
 142
 143 #define current_uid_gid(_uid, _gid)             \
 144 do {                                            \
 145         *(_uid) = current->cred->uid;           \
 146         *(_gid) = current->cred->gid;           \
 147 } while(0)
 148
 149 #define current_euid_egid(_uid, _gid)           \
 150 do {                                            \
 151         *(_uid) = current->cred->euid;          \
 152         *(_gid) = current->cred->egid;          \
 153 } while(0)
 154
 155 #define current_fsuid_fsgid(_uid, _gid)         \
 156 do {                                            \
 157         *(_uid) = current->cred->fsuid;         \
 158         *(_gid) = current->cred->fsgid;         \
 159 } while(0)
 160
 161 #endif /* _LINUX_CRED_H */