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a9681bf3 DH |
1 | /* In-software asymmetric public-key crypto subtype |
2 | * | |
3 | * See Documentation/crypto/asymmetric-keys.txt | |
4 | * | |
5 | * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved. | |
6 | * Written by David Howells (dhowells@redhat.com) | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or | |
9 | * modify it under the terms of the GNU General Public Licence | |
10 | * as published by the Free Software Foundation; either version | |
11 | * 2 of the Licence, or (at your option) any later version. | |
12 | */ | |
13 | ||
14 | #define pr_fmt(fmt) "PKEY: "fmt | |
15 | #include <linux/module.h> | |
16 | #include <linux/export.h> | |
17 | #include <linux/kernel.h> | |
18 | #include <linux/slab.h> | |
19 | #include <linux/seq_file.h> | |
d43de6c7 | 20 | #include <linux/scatterlist.h> |
a9681bf3 | 21 | #include <keys/asymmetric-subtype.h> |
db6c43bd | 22 | #include <crypto/public_key.h> |
d43de6c7 | 23 | #include <crypto/akcipher.h> |
a9681bf3 | 24 | |
1e684d38 DH |
25 | MODULE_DESCRIPTION("In-software asymmetric public-key subtype"); |
26 | MODULE_AUTHOR("Red Hat, Inc."); | |
a9681bf3 DH |
27 | MODULE_LICENSE("GPL"); |
28 | ||
a9681bf3 DH |
29 | /* |
30 | * Provide a part of a description of the key for /proc/keys. | |
31 | */ | |
32 | static void public_key_describe(const struct key *asymmetric_key, | |
33 | struct seq_file *m) | |
34 | { | |
146aa8b1 | 35 | struct public_key *key = asymmetric_key->payload.data[asym_crypto]; |
a9681bf3 DH |
36 | |
37 | if (key) | |
4e8ae72a | 38 | seq_printf(m, "%s.%s", key->id_type, key->pkey_algo); |
a9681bf3 DH |
39 | } |
40 | ||
41 | /* | |
42 | * Destroy a public key algorithm key. | |
43 | */ | |
3b764563 | 44 | void public_key_free(struct public_key *key) |
a9681bf3 | 45 | { |
3b764563 | 46 | if (key) { |
db6c43bd | 47 | kfree(key->key); |
3b764563 DH |
48 | kfree(key); |
49 | } | |
50 | } | |
51 | EXPORT_SYMBOL_GPL(public_key_free); | |
52 | ||
53 | /* | |
54 | * Destroy a public key algorithm key. | |
55 | */ | |
56 | static void public_key_destroy(void *payload0, void *payload3) | |
57 | { | |
58 | public_key_free(payload0); | |
59 | public_key_signature_free(payload3); | |
a9681bf3 | 60 | } |
a9681bf3 DH |
61 | |
62 | /* | |
63 | * Verify a signature using a public key. | |
64 | */ | |
db6c43bd | 65 | int public_key_verify_signature(const struct public_key *pkey, |
3d167d68 | 66 | const struct public_key_signature *sig) |
a9681bf3 | 67 | { |
0ca2a04a | 68 | struct crypto_wait cwait; |
d43de6c7 DH |
69 | struct crypto_akcipher *tfm; |
70 | struct akcipher_request *req; | |
71 | struct scatterlist sig_sg, digest_sg; | |
72 | const char *alg_name; | |
73 | char alg_name_buf[CRYPTO_MAX_ALG_NAME]; | |
74 | void *output; | |
75 | unsigned int outlen; | |
72f9a07b | 76 | int ret; |
d43de6c7 DH |
77 | |
78 | pr_devel("==>%s()\n", __func__); | |
79 | ||
db6c43bd | 80 | BUG_ON(!pkey); |
3d167d68 DH |
81 | BUG_ON(!sig); |
82 | BUG_ON(!sig->digest); | |
db6c43bd | 83 | BUG_ON(!sig->s); |
a9681bf3 | 84 | |
4e8ae72a DH |
85 | alg_name = sig->pkey_algo; |
86 | if (strcmp(sig->pkey_algo, "rsa") == 0) { | |
d43de6c7 DH |
87 | /* The data wangled by the RSA algorithm is typically padded |
88 | * and encoded in some manner, such as EMSA-PKCS1-1_5 [RFC3447 | |
89 | * sec 8.2]. | |
90 | */ | |
91 | if (snprintf(alg_name_buf, CRYPTO_MAX_ALG_NAME, | |
4e8ae72a | 92 | "pkcs1pad(rsa,%s)", sig->hash_algo |
d43de6c7 DH |
93 | ) >= CRYPTO_MAX_ALG_NAME) |
94 | return -EINVAL; | |
95 | alg_name = alg_name_buf; | |
96 | } | |
97 | ||
98 | tfm = crypto_alloc_akcipher(alg_name, 0, 0); | |
99 | if (IS_ERR(tfm)) | |
100 | return PTR_ERR(tfm); | |
101 | ||
72f9a07b | 102 | ret = -ENOMEM; |
d43de6c7 DH |
103 | req = akcipher_request_alloc(tfm, GFP_KERNEL); |
104 | if (!req) | |
105 | goto error_free_tfm; | |
106 | ||
107 | ret = crypto_akcipher_set_pub_key(tfm, pkey->key, pkey->keylen); | |
108 | if (ret) | |
109 | goto error_free_req; | |
110 | ||
fbb72630 | 111 | ret = -ENOMEM; |
d43de6c7 DH |
112 | outlen = crypto_akcipher_maxsize(tfm); |
113 | output = kmalloc(outlen, GFP_KERNEL); | |
114 | if (!output) | |
115 | goto error_free_req; | |
116 | ||
117 | sg_init_one(&sig_sg, sig->s, sig->s_size); | |
118 | sg_init_one(&digest_sg, output, outlen); | |
119 | akcipher_request_set_crypt(req, &sig_sg, &digest_sg, sig->s_size, | |
120 | outlen); | |
0ca2a04a | 121 | crypto_init_wait(&cwait); |
d43de6c7 DH |
122 | akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG | |
123 | CRYPTO_TFM_REQ_MAY_SLEEP, | |
0ca2a04a | 124 | crypto_req_done, &cwait); |
d43de6c7 DH |
125 | |
126 | /* Perform the verification calculation. This doesn't actually do the | |
127 | * verification, but rather calculates the hash expected by the | |
128 | * signature and returns that to us. | |
129 | */ | |
0ca2a04a | 130 | ret = crypto_wait_req(crypto_akcipher_verify(req), &cwait); |
72f9a07b | 131 | if (ret) |
d43de6c7 | 132 | goto out_free_output; |
a9681bf3 | 133 | |
d43de6c7 DH |
134 | /* Do the actual verification step. */ |
135 | if (req->dst_len != sig->digest_size || | |
136 | memcmp(sig->digest, output, sig->digest_size) != 0) | |
137 | ret = -EKEYREJECTED; | |
a9681bf3 | 138 | |
d43de6c7 DH |
139 | out_free_output: |
140 | kfree(output); | |
141 | error_free_req: | |
142 | akcipher_request_free(req); | |
143 | error_free_tfm: | |
144 | crypto_free_akcipher(tfm); | |
145 | pr_devel("<==%s() = %d\n", __func__, ret); | |
72f9a07b EB |
146 | if (WARN_ON_ONCE(ret > 0)) |
147 | ret = -EINVAL; | |
d43de6c7 | 148 | return ret; |
3d167d68 DH |
149 | } |
150 | EXPORT_SYMBOL_GPL(public_key_verify_signature); | |
151 | ||
152 | static int public_key_verify_signature_2(const struct key *key, | |
153 | const struct public_key_signature *sig) | |
154 | { | |
146aa8b1 | 155 | const struct public_key *pk = key->payload.data[asym_crypto]; |
3d167d68 | 156 | return public_key_verify_signature(pk, sig); |
a9681bf3 DH |
157 | } |
158 | ||
159 | /* | |
160 | * Public key algorithm asymmetric key subtype | |
161 | */ | |
162 | struct asymmetric_key_subtype public_key_subtype = { | |
163 | .owner = THIS_MODULE, | |
164 | .name = "public_key", | |
876c6e3e | 165 | .name_len = sizeof("public_key") - 1, |
a9681bf3 DH |
166 | .describe = public_key_describe, |
167 | .destroy = public_key_destroy, | |
3d167d68 | 168 | .verify_signature = public_key_verify_signature_2, |
a9681bf3 DH |
169 | }; |
170 | EXPORT_SYMBOL_GPL(public_key_subtype); |