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cfb664ff DH |
1 | /* Instantiate a public key crypto key from an X.509 Certificate |
2 | * | |
a511e1af | 3 | * Copyright (C) 2012, 2016 Red Hat, Inc. All Rights Reserved. |
cfb664ff DH |
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 | ||
a511e1af | 12 | #define pr_fmt(fmt) "ASYM: "fmt |
cfb664ff DH |
13 | #include <linux/module.h> |
14 | #include <linux/kernel.h> | |
cfb664ff | 15 | #include <linux/err.h> |
cfb664ff DH |
16 | #include <crypto/public_key.h> |
17 | #include "asymmetric_keys.h" | |
cfb664ff DH |
18 | |
19 | static bool use_builtin_keys; | |
20 | static struct asymmetric_key_id *ca_keyid; | |
21 | ||
22 | #ifndef MODULE | |
23 | static struct { | |
24 | struct asymmetric_key_id id; | |
25 | unsigned char data[10]; | |
26 | } cakey; | |
27 | ||
28 | static int __init ca_keys_setup(char *str) | |
29 | { | |
30 | if (!str) /* default system keyring */ | |
31 | return 1; | |
32 | ||
33 | if (strncmp(str, "id:", 3) == 0) { | |
34 | struct asymmetric_key_id *p = &cakey.id; | |
35 | size_t hexlen = (strlen(str) - 3) / 2; | |
36 | int ret; | |
37 | ||
38 | if (hexlen == 0 || hexlen > sizeof(cakey.data)) { | |
39 | pr_err("Missing or invalid ca_keys id\n"); | |
40 | return 1; | |
41 | } | |
42 | ||
43 | ret = __asymmetric_key_hex_to_key_id(str + 3, p, hexlen); | |
44 | if (ret < 0) | |
45 | pr_err("Unparsable ca_keys id hex string\n"); | |
46 | else | |
47 | ca_keyid = p; /* owner key 'id:xxxxxx' */ | |
48 | } else if (strcmp(str, "builtin") == 0) { | |
49 | use_builtin_keys = true; | |
50 | } | |
51 | ||
52 | return 1; | |
53 | } | |
54 | __setup("ca_keys=", ca_keys_setup); | |
55 | #endif | |
56 | ||
a511e1af DH |
57 | /** |
58 | * restrict_link_by_signature - Restrict additions to a ring of public keys | |
59 | * @trust_keyring: A ring of keys that can be used to vouch for the new cert. | |
60 | * @type: The type of key being added. | |
61 | * @payload: The payload of the new key. | |
62 | * | |
cfb664ff DH |
63 | * Check the new certificate against the ones in the trust keyring. If one of |
64 | * those is the signing key and validates the new certificate, then mark the | |
65 | * new certificate as being trusted. | |
66 | * | |
a511e1af DH |
67 | * Returns 0 if the new certificate was accepted, -ENOKEY if we couldn't find a |
68 | * matching parent certificate in the trusted list, -EKEYREJECTED if the | |
69 | * signature check fails or the key is blacklisted and some other error if | |
70 | * there is a matching certificate but the signature check cannot be performed. | |
cfb664ff | 71 | */ |
a511e1af DH |
72 | int restrict_link_by_signature(struct key *trust_keyring, |
73 | const struct key_type *type, | |
74 | const union key_payload *payload) | |
cfb664ff | 75 | { |
a511e1af | 76 | const struct public_key_signature *sig; |
cfb664ff | 77 | struct key *key; |
a511e1af | 78 | int ret; |
cfb664ff | 79 | |
a511e1af | 80 | pr_devel("==>%s()\n", __func__); |
cfb664ff DH |
81 | |
82 | if (!trust_keyring) | |
a511e1af DH |
83 | return -ENOKEY; |
84 | ||
85 | if (type != &key_type_asymmetric) | |
cfb664ff | 86 | return -EOPNOTSUPP; |
a511e1af DH |
87 | |
88 | sig = payload->data[asym_auth]; | |
89 | if (!sig->auth_ids[0] && !sig->auth_ids[1]) | |
acddc720 | 90 | return -ENOKEY; |
a511e1af | 91 | |
cfb664ff DH |
92 | if (ca_keyid && !asymmetric_key_id_partial(sig->auth_ids[1], ca_keyid)) |
93 | return -EPERM; | |
cfb664ff | 94 | |
a511e1af | 95 | /* See if we have a key that signed this one. */ |
cfb664ff DH |
96 | key = find_asymmetric_key(trust_keyring, |
97 | sig->auth_ids[0], sig->auth_ids[1], | |
98 | false); | |
99 | if (IS_ERR(key)) | |
a511e1af | 100 | return -ENOKEY; |
cfb664ff | 101 | |
a511e1af DH |
102 | if (use_builtin_keys && !test_bit(KEY_FLAG_BUILTIN, &key->flags)) |
103 | ret = -ENOKEY; | |
104 | else | |
105 | ret = verify_signature(key, sig); | |
cfb664ff DH |
106 | key_put(key); |
107 | return ret; | |
108 | } |