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f36f8c75 DH |
1 | /* General persistent per-UID keyrings register |
2 | * | |
3 | * Copyright (C) 2013 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/user_namespace.h> | |
5b825c3a IM |
13 | #include <linux/cred.h> |
14 | ||
f36f8c75 DH |
15 | #include "internal.h" |
16 | ||
17 | unsigned persistent_keyring_expiry = 3 * 24 * 3600; /* Expire after 3 days of non-use */ | |
18 | ||
19 | /* | |
20 | * Create the persistent keyring register for the current user namespace. | |
21 | * | |
22 | * Called with the namespace's sem locked for writing. | |
23 | */ | |
24 | static int key_create_persistent_register(struct user_namespace *ns) | |
25 | { | |
26 | struct key *reg = keyring_alloc(".persistent_register", | |
27 | KUIDT_INIT(0), KGIDT_INIT(0), | |
28 | current_cred(), | |
29 | ((KEY_POS_ALL & ~KEY_POS_SETATTR) | | |
30 | KEY_USR_VIEW | KEY_USR_READ), | |
5ac7eace | 31 | KEY_ALLOC_NOT_IN_QUOTA, NULL, NULL); |
f36f8c75 DH |
32 | if (IS_ERR(reg)) |
33 | return PTR_ERR(reg); | |
34 | ||
35 | ns->persistent_keyring_register = reg; | |
36 | return 0; | |
37 | } | |
38 | ||
39 | /* | |
40 | * Create the persistent keyring for the specified user. | |
41 | * | |
42 | * Called with the namespace's sem locked for writing. | |
43 | */ | |
44 | static key_ref_t key_create_persistent(struct user_namespace *ns, kuid_t uid, | |
45 | struct keyring_index_key *index_key) | |
46 | { | |
47 | struct key *persistent; | |
48 | key_ref_t reg_ref, persistent_ref; | |
49 | ||
50 | if (!ns->persistent_keyring_register) { | |
51 | long err = key_create_persistent_register(ns); | |
52 | if (err < 0) | |
53 | return ERR_PTR(err); | |
54 | } else { | |
55 | reg_ref = make_key_ref(ns->persistent_keyring_register, true); | |
56 | persistent_ref = find_key_to_update(reg_ref, index_key); | |
57 | if (persistent_ref) | |
58 | return persistent_ref; | |
59 | } | |
60 | ||
61 | persistent = keyring_alloc(index_key->description, | |
62 | uid, INVALID_GID, current_cred(), | |
63 | ((KEY_POS_ALL & ~KEY_POS_SETATTR) | | |
64 | KEY_USR_VIEW | KEY_USR_READ), | |
5ac7eace | 65 | KEY_ALLOC_NOT_IN_QUOTA, NULL, |
f36f8c75 DH |
66 | ns->persistent_keyring_register); |
67 | if (IS_ERR(persistent)) | |
68 | return ERR_CAST(persistent); | |
69 | ||
70 | return make_key_ref(persistent, true); | |
71 | } | |
72 | ||
73 | /* | |
74 | * Get the persistent keyring for a specific UID and link it to the nominated | |
75 | * keyring. | |
76 | */ | |
77 | static long key_get_persistent(struct user_namespace *ns, kuid_t uid, | |
78 | key_ref_t dest_ref) | |
79 | { | |
80 | struct keyring_index_key index_key; | |
81 | struct key *persistent; | |
82 | key_ref_t reg_ref, persistent_ref; | |
83 | char buf[32]; | |
84 | long ret; | |
85 | ||
86 | /* Look in the register if it exists */ | |
87 | index_key.type = &key_type_keyring; | |
88 | index_key.description = buf; | |
89 | index_key.desc_len = sprintf(buf, "_persistent.%u", from_kuid(ns, uid)); | |
90 | ||
91 | if (ns->persistent_keyring_register) { | |
92 | reg_ref = make_key_ref(ns->persistent_keyring_register, true); | |
93 | down_read(&ns->persistent_keyring_register_sem); | |
94 | persistent_ref = find_key_to_update(reg_ref, &index_key); | |
95 | up_read(&ns->persistent_keyring_register_sem); | |
96 | ||
97 | if (persistent_ref) | |
98 | goto found; | |
99 | } | |
100 | ||
101 | /* It wasn't in the register, so we'll need to create it. We might | |
102 | * also need to create the register. | |
103 | */ | |
104 | down_write(&ns->persistent_keyring_register_sem); | |
105 | persistent_ref = key_create_persistent(ns, uid, &index_key); | |
106 | up_write(&ns->persistent_keyring_register_sem); | |
107 | if (!IS_ERR(persistent_ref)) | |
108 | goto found; | |
109 | ||
110 | return PTR_ERR(persistent_ref); | |
111 | ||
112 | found: | |
f5895943 | 113 | ret = key_task_permission(persistent_ref, current_cred(), KEY_NEED_LINK); |
f36f8c75 DH |
114 | if (ret == 0) { |
115 | persistent = key_ref_to_ptr(persistent_ref); | |
116 | ret = key_link(key_ref_to_ptr(dest_ref), persistent); | |
117 | if (ret == 0) { | |
118 | key_set_timeout(persistent, persistent_keyring_expiry); | |
965475ac | 119 | ret = persistent->serial; |
f36f8c75 DH |
120 | } |
121 | } | |
122 | ||
123 | key_ref_put(persistent_ref); | |
124 | return ret; | |
125 | } | |
126 | ||
127 | /* | |
128 | * Get the persistent keyring for a specific UID and link it to the nominated | |
129 | * keyring. | |
130 | */ | |
131 | long keyctl_get_persistent(uid_t _uid, key_serial_t destid) | |
132 | { | |
133 | struct user_namespace *ns = current_user_ns(); | |
134 | key_ref_t dest_ref; | |
135 | kuid_t uid; | |
136 | long ret; | |
137 | ||
138 | /* -1 indicates the current user */ | |
139 | if (_uid == (uid_t)-1) { | |
140 | uid = current_uid(); | |
141 | } else { | |
142 | uid = make_kuid(ns, _uid); | |
143 | if (!uid_valid(uid)) | |
144 | return -EINVAL; | |
145 | ||
146 | /* You can only see your own persistent cache if you're not | |
147 | * sufficiently privileged. | |
148 | */ | |
fbf8c53f DH |
149 | if (!uid_eq(uid, current_uid()) && |
150 | !uid_eq(uid, current_euid()) && | |
f36f8c75 DH |
151 | !ns_capable(ns, CAP_SETUID)) |
152 | return -EPERM; | |
153 | } | |
154 | ||
155 | /* There must be a destination keyring */ | |
f5895943 | 156 | dest_ref = lookup_user_key(destid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE); |
f36f8c75 DH |
157 | if (IS_ERR(dest_ref)) |
158 | return PTR_ERR(dest_ref); | |
159 | if (key_ref_to_ptr(dest_ref)->type != &key_type_keyring) { | |
160 | ret = -ENOTDIR; | |
161 | goto out_put_dest; | |
162 | } | |
163 | ||
164 | ret = key_get_persistent(ns, uid, dest_ref); | |
165 | ||
166 | out_put_dest: | |
167 | key_ref_put(dest_ref); | |
168 | return ret; | |
169 | } |