1 /*
2 * Copyright (C) 2013 Intel Corporation
3 *
4 * Author:
5 * Dmitry Kasatkin <dmitry.kasatkin@intel.com>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation, version 2 of the License.
10 *
11 */
12
13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
14
15 #include <linux/err.h>
16 #include <linux/ratelimit.h>
17 #include <linux/key-type.h>
18 #include <crypto/public_key.h>
19 #include <keys/asymmetric-type.h>
20
21 #include "integrity.h"
22
23 /*
24 * Request an asymmetric key.
25 */
request_asymmetric_key(struct key * keyring,uint32_t keyid)26 static struct key *request_asymmetric_key(struct key *keyring, uint32_t keyid)
27 {
28 struct key *key;
29 char name[12];
30
31 sprintf(name, "id:%08x", keyid);
32
33 pr_debug("key search: \"%s\"\n", name);
34
35 if (keyring) {
36 /* search in specific keyring */
37 key_ref_t kref;
38 kref = keyring_search(make_key_ref(keyring, 1),
39 &key_type_asymmetric, name);
40 if (IS_ERR(kref))
41 key = ERR_CAST(kref);
42 else
43 key = key_ref_to_ptr(kref);
44 } else {
45 key = request_key(&key_type_asymmetric, name, NULL);
46 }
47
48 if (IS_ERR(key)) {
49 pr_err_ratelimited("Request for unknown key '%s' err %ld\n",
50 name, PTR_ERR(key));
51 switch (PTR_ERR(key)) {
52 /* Hide some search errors */
53 case -EACCES:
54 case -ENOTDIR:
55 case -EAGAIN:
56 return ERR_PTR(-ENOKEY);
57 default:
58 return key;
59 }
60 }
61
62 pr_debug("%s() = 0 [%x]\n", __func__, key_serial(key));
63
64 return key;
65 }
66
asymmetric_verify(struct key * keyring,const char * sig,int siglen,const char * data,int datalen)67 int asymmetric_verify(struct key *keyring, const char *sig,
68 int siglen, const char *data, int datalen)
69 {
70 struct public_key_signature pks;
71 struct signature_v2_hdr *hdr = (struct signature_v2_hdr *)sig;
72 struct key *key;
73 int ret = -ENOMEM;
74
75 if (siglen <= sizeof(*hdr))
76 return -EBADMSG;
77
78 siglen -= sizeof(*hdr);
79
80 if (siglen != __be16_to_cpu(hdr->sig_size))
81 return -EBADMSG;
82
83 if (hdr->hash_algo >= PKEY_HASH__LAST)
84 return -ENOPKG;
85
86 key = request_asymmetric_key(keyring, __be32_to_cpu(hdr->keyid));
87 if (IS_ERR(key))
88 return PTR_ERR(key);
89
90 memset(&pks, 0, sizeof(pks));
91
92 pks.pkey_hash_algo = hdr->hash_algo;
93 pks.digest = (u8 *)data;
94 pks.digest_size = datalen;
95 pks.nr_mpi = 1;
96 pks.rsa.s = mpi_read_raw_data(hdr->sig, siglen);
97
98 if (pks.rsa.s)
99 ret = verify_signature(key, &pks);
100
101 mpi_free(pks.rsa.s);
102 key_put(key);
103 pr_debug("%s() = %d\n", __func__, ret);
104 return ret;
105 }
106