CRED: Detach the credentials from task_struct
[linux-2.6.git] / include / linux / cred.h
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 extern void __put_cred(struct cred *);
162 extern int copy_creds(struct task_struct *, unsigned long);
163
164 /**
165  * get_cred - Get a reference on a set of credentials
166  * @cred: The credentials to reference
167  *
168  * Get a reference on the specified set of credentials.  The caller must
169  * release the reference.
170  */
171 static inline struct cred *get_cred(struct cred *cred)
172 {
173         atomic_inc(&cred->usage);
174         return cred;
175 }
176
177 /**
178  * put_cred - Release a reference to a set of credentials
179  * @cred: The credentials to release
180  *
181  * Release a reference to a set of credentials, deleting them when the last ref
182  * is released.
183  */
184 static inline void put_cred(struct cred *cred)
185 {
186         if (atomic_dec_and_test(&(cred)->usage))
187                 __put_cred(cred);
188 }
189
190 #endif /* _LINUX_CRED_H */