projects / deliverable / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| 9ae326a6 DH |
1 | /* CacheFiles security management |
| 2 | * | |
| 3 | * Copyright (C) 2007 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 | #include <linux/fs.h> | |
| 13 | #include <linux/cred.h> | |
| 14 | #include "internal.h" | |
| 15 | ||
| 16 | /* | |
| 17 | * determine the security context within which we access the cache from within | |
| 18 | * the kernel | |
| 19 | */ | |
| 20 | int cachefiles_get_security_ID(struct cachefiles_cache *cache) | |
| 21 | { | |
| 22 | struct cred *new; | |
| 23 | int ret; | |
| 24 | ||
| 25 | _enter("{%s}", cache->secctx); | |
| 26 | ||
| 27 | new = prepare_kernel_cred(current); | |
| 28 | if (!new) { | |
| 29 | ret = -ENOMEM; | |
| 30 | goto error; | |
| 31 | } | |
| 32 | ||
| 33 | if (cache->secctx) { | |
| 34 | ret = set_security_override_from_ctx(new, cache->secctx); | |
| 35 | if (ret < 0) { | |
| 36 | put_cred(new); | |
| 37 | printk(KERN_ERR "CacheFiles:" | |
| 38 | " Security denies permission to nominate" | |
| 39 | " security context: error %d\n", | |
| 40 | ret); | |
| 41 | goto error; | |
| 42 | } | |
| 43 | } | |
| 44 | ||
| 45 | cache->cache_cred = new; | |
| 46 | ret = 0; | |
| 47 | error: | |
| 48 | _leave(" = %d", ret); | |
| 49 | return ret; | |
| 50 | } | |
| 51 | ||
| 52 | /* | |
| 53 | * see if mkdir and create can be performed in the root directory | |
| 54 | */ | |
| 55 | static int cachefiles_check_cache_dir(struct cachefiles_cache *cache, | |
| 56 | struct dentry *root) | |
| 57 | { | |
| 58 | int ret; | |
| 59 | ||
| 60 | ret = security_inode_mkdir(root->d_inode, root, 0); | |
| 61 | if (ret < 0) { | |
| 62 | printk(KERN_ERR "CacheFiles:" | |
| 63 | " Security denies permission to make dirs: error %d", | |
| 64 | ret); | |
| 65 | return ret; | |
| 66 | } | |
| 67 | ||
| 68 | ret = security_inode_create(root->d_inode, root, 0); | |
| 69 | if (ret < 0) | |
| 70 | printk(KERN_ERR "CacheFiles:" | |
| 71 | " Security denies permission to create files: error %d", | |
| 72 | ret); | |
| 73 | ||
| 74 | return ret; | |
| 75 | } | |
| 76 | ||
| 77 | /* | |
| 78 | * check the security details of the on-disk cache | |
| 79 | * - must be called with security override in force | |
| 80 | */ | |
| 81 | int cachefiles_determine_cache_security(struct cachefiles_cache *cache, | |
| 82 | struct dentry *root, | |
| 83 | const struct cred **_saved_cred) | |
| 84 | { | |
| 85 | struct cred *new; | |
| 86 | int ret; | |
| 87 | ||
| 88 | _enter(""); | |
| 89 | ||
| 90 | /* duplicate the cache creds for COW (the override is currently in | |
| 91 | * force, so we can use prepare_creds() to do this) */ | |
| 92 | new = prepare_creds(); | |
| 93 | if (!new) | |
| 94 | return -ENOMEM; | |
| 95 | ||
| 96 | cachefiles_end_secure(cache, *_saved_cred); | |
| 97 | ||
| 98 | /* use the cache root dir's security context as the basis with | |
| 99 | * which create files */ | |
| 100 | ret = set_create_files_as(new, root->d_inode); | |
| 101 | if (ret < 0) { | |
| 102 | _leave(" = %d [cfa]", ret); | |
| 103 | return ret; | |
| 104 | } | |
| 105 | ||
| 106 | put_cred(cache->cache_cred); | |
| 107 | cache->cache_cred = new; | |
| 108 | ||
| 109 | cachefiles_begin_secure(cache, _saved_cred); | |
| 110 | ret = cachefiles_check_cache_dir(cache, root); | |
| 111 | ||
| 112 | if (ret == -EOPNOTSUPP) | |
| 113 | ret = 0; | |
| 114 | _leave(" = %d", ret); | |
| 115 | return ret; | |
| 116 | } |