projects / linux-2.6-block.git / blame
| Commit | Line | Data |
|---|---|---|
| 468ed2b0 DH |
1 | /* permission.c: key permission determination |
| 2 | * | |
| 3 | * Copyright (C) 2005 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 License | |
| 8 | * as published by the Free Software Foundation; either version | |
| 9 | * 2 of the License, or (at your option) any later version. | |
| 10 | */ | |
| 11 | ||
| 12 | #include <linux/module.h> | |
| 13 | #include "internal.h" | |
| 14 | ||
| 15 | /*****************************************************************************/ | |
| 16 | /* | |
| 17 | * check to see whether permission is granted to use a key in the desired way, | |
| 18 | * but permit the security modules to override | |
| 19 | */ | |
| 20 | int key_task_permission(const key_ref_t key_ref, | |
| 21 | struct task_struct *context, | |
| 22 | key_perm_t perm) | |
| 23 | { | |
| 24 | struct key *key; | |
| 25 | key_perm_t kperm; | |
| 26 | int ret; | |
| 27 | ||
| 28 | key = key_ref_to_ptr(key_ref); | |
| 29 | ||
| 468ed2b0 DH |
30 | /* use the second 8-bits of permissions for keys the caller owns */ |
| 31 | if (key->uid == context->fsuid) { | |
| 32 | kperm = key->perm >> 16; | |
| 33 | goto use_these_perms; | |
| 34 | } | |
| 35 | ||
| 36 | /* use the third 8-bits of permissions for keys the caller has a group | |
| 37 | * membership in common with */ | |
| 38 | if (key->gid != -1 && key->perm & KEY_GRP_ALL) { | |
| 39 | if (key->gid == context->fsgid) { | |
| 40 | kperm = key->perm >> 8; | |
| 41 | goto use_these_perms; | |
| 42 | } | |
| 43 | ||
| 44 | task_lock(context); | |
| 45 | ret = groups_search(context->group_info, key->gid); | |
| 46 | task_unlock(context); | |
| 47 | ||
| 48 | if (ret) { | |
| 49 | kperm = key->perm >> 8; | |
| 50 | goto use_these_perms; | |
| 51 | } | |
| 52 | } | |
| 53 | ||
| 54 | /* otherwise use the least-significant 8-bits */ | |
| 55 | kperm = key->perm; | |
| 56 | ||
| 57 | use_these_perms: | |
| 7ab501db DH |
58 | /* use the top 8-bits of permissions for keys the caller possesses |
| 59 | * - possessor permissions are additive with other permissions | |
| 60 | */ | |
| 61 | if (is_key_possessed(key_ref)) | |
| 62 | kperm |= key->perm >> 24; | |
| 63 | ||
| 468ed2b0 DH |
64 | kperm = kperm & perm & KEY_ALL; |
| 65 | ||
| 66 | return kperm == perm; | |
| 67 | ||
| 68 | } /* end key_task_permission() */ | |
| 69 | ||
| 70 | EXPORT_SYMBOL(key_task_permission); |