David Howells | 9e2b2dc | 2008-08-13 16:20:04 +0100 | [diff] [blame] | 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 | |
David Howells | b6dff3e | 2008-11-14 10:39:16 +1100 | [diff] [blame] | 15 | #include <linux/capability.h> |
| 16 | #include <linux/key.h> |
| 17 | #include <asm/atomic.h> |
David Howells | 9e2b2dc | 2008-08-13 16:20:04 +0100 | [diff] [blame] | 18 | |
David Howells | b6dff3e | 2008-11-14 10:39:16 +1100 | [diff] [blame] | 19 | struct user_struct; |
| 20 | struct cred; |
David Howells | 9e2b2dc | 2008-08-13 16:20:04 +0100 | [diff] [blame] | 21 | |
David Howells | b6dff3e | 2008-11-14 10:39:16 +1100 | [diff] [blame] | 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) |
David Howells | 9e2b2dc | 2008-08-13 16:20:04 +0100 | [diff] [blame] | 142 | |
| 143 | #define current_uid_gid(_uid, _gid) \ |
| 144 | do { \ |
David Howells | b6dff3e | 2008-11-14 10:39:16 +1100 | [diff] [blame] | 145 | *(_uid) = current->cred->uid; \ |
| 146 | *(_gid) = current->cred->gid; \ |
David Howells | 9e2b2dc | 2008-08-13 16:20:04 +0100 | [diff] [blame] | 147 | } while(0) |
| 148 | |
| 149 | #define current_euid_egid(_uid, _gid) \ |
| 150 | do { \ |
David Howells | b6dff3e | 2008-11-14 10:39:16 +1100 | [diff] [blame] | 151 | *(_uid) = current->cred->euid; \ |
| 152 | *(_gid) = current->cred->egid; \ |
David Howells | 9e2b2dc | 2008-08-13 16:20:04 +0100 | [diff] [blame] | 153 | } while(0) |
| 154 | |
| 155 | #define current_fsuid_fsgid(_uid, _gid) \ |
| 156 | do { \ |
David Howells | b6dff3e | 2008-11-14 10:39:16 +1100 | [diff] [blame] | 157 | *(_uid) = current->cred->fsuid; \ |
| 158 | *(_gid) = current->cred->fsgid; \ |
David Howells | 9e2b2dc | 2008-08-13 16:20:04 +0100 | [diff] [blame] | 159 | } while(0) |
| 160 | |
David Howells | f1752ee | 2008-11-14 10:39:17 +1100 | [diff] [blame^] | 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 | |
David Howells | 9e2b2dc | 2008-08-13 16:20:04 +0100 | [diff] [blame] | 190 | #endif /* _LINUX_CRED_H */ |