1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* In-software asymmetric public-key crypto subtype
3 *
4 * See Documentation/crypto/asymmetric-keys.txt
5 *
6 * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
7 * Written by David Howells (dhowells@redhat.com)
8 */
9
10 #define pr_fmt(fmt) "PKEY: "fmt
11 #include <linux/module.h>
12 #include <linux/export.h>
13 #include <linux/kernel.h>
14 #include <linux/slab.h>
15 #include <linux/seq_file.h>
16 #include <linux/scatterlist.h>
17 #include <keys/asymmetric-subtype.h>
18 #include <crypto/public_key.h>
19 #include <crypto/akcipher.h>
20
21 MODULE_DESCRIPTION("In-software asymmetric public-key subtype");
22 MODULE_AUTHOR("Red Hat, Inc.");
23 MODULE_LICENSE("GPL");
24
25 /*
26 * Provide a part of a description of the key for /proc/keys.
27 */
public_key_describe(const struct key * asymmetric_key,struct seq_file * m)28 static void public_key_describe(const struct key *asymmetric_key,
29 struct seq_file *m)
30 {
31 struct public_key *key = asymmetric_key->payload.data[asym_crypto];
32
33 if (key)
34 seq_printf(m, "%s.%s", key->id_type, key->pkey_algo);
35 }
36
37 /*
38 * Destroy a public key algorithm key.
39 */
public_key_free(struct public_key * key)40 void public_key_free(struct public_key *key)
41 {
42 if (key) {
43 kfree(key->key);
44 kfree(key->params);
45 kfree(key);
46 }
47 }
48 EXPORT_SYMBOL_GPL(public_key_free);
49
50 /*
51 * Destroy a public key algorithm key.
52 */
public_key_destroy(void * payload0,void * payload3)53 static void public_key_destroy(void *payload0, void *payload3)
54 {
55 public_key_free(payload0);
56 public_key_signature_free(payload3);
57 }
58
59 /*
60 * Determine the crypto algorithm name.
61 */
62 static
software_key_determine_akcipher(const char * encoding,const char * hash_algo,const struct public_key * pkey,char alg_name[CRYPTO_MAX_ALG_NAME])63 int software_key_determine_akcipher(const char *encoding,
64 const char *hash_algo,
65 const struct public_key *pkey,
66 char alg_name[CRYPTO_MAX_ALG_NAME])
67 {
68 int n;
69
70 if (strcmp(encoding, "pkcs1") == 0) {
71 /* The data wangled by the RSA algorithm is typically padded
72 * and encoded in some manner, such as EMSA-PKCS1-1_5 [RFC3447
73 * sec 8.2].
74 */
75 if (!hash_algo)
76 n = snprintf(alg_name, CRYPTO_MAX_ALG_NAME,
77 "pkcs1pad(%s)",
78 pkey->pkey_algo);
79 else
80 n = snprintf(alg_name, CRYPTO_MAX_ALG_NAME,
81 "pkcs1pad(%s,%s)",
82 pkey->pkey_algo, hash_algo);
83 return n >= CRYPTO_MAX_ALG_NAME ? -EINVAL : 0;
84 }
85
86 if (strcmp(encoding, "raw") == 0) {
87 strcpy(alg_name, pkey->pkey_algo);
88 return 0;
89 }
90
91 return -ENOPKG;
92 }
93
pkey_pack_u32(u8 * dst,u32 val)94 static u8 *pkey_pack_u32(u8 *dst, u32 val)
95 {
96 memcpy(dst, &val, sizeof(val));
97 return dst + sizeof(val);
98 }
99
100 /*
101 * Query information about a key.
102 */
software_key_query(const struct kernel_pkey_params * params,struct kernel_pkey_query * info)103 static int software_key_query(const struct kernel_pkey_params *params,
104 struct kernel_pkey_query *info)
105 {
106 struct crypto_akcipher *tfm;
107 struct public_key *pkey = params->key->payload.data[asym_crypto];
108 char alg_name[CRYPTO_MAX_ALG_NAME];
109 u8 *key, *ptr;
110 int ret, len;
111
112 ret = software_key_determine_akcipher(params->encoding,
113 params->hash_algo,
114 pkey, alg_name);
115 if (ret < 0)
116 return ret;
117
118 tfm = crypto_alloc_akcipher(alg_name, 0, 0);
119 if (IS_ERR(tfm))
120 return PTR_ERR(tfm);
121
122 key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
123 GFP_KERNEL);
124 if (!key)
125 goto error_free_tfm;
126 memcpy(key, pkey->key, pkey->keylen);
127 ptr = key + pkey->keylen;
128 ptr = pkey_pack_u32(ptr, pkey->algo);
129 ptr = pkey_pack_u32(ptr, pkey->paramlen);
130 memcpy(ptr, pkey->params, pkey->paramlen);
131
132 if (pkey->key_is_private)
133 ret = crypto_akcipher_set_priv_key(tfm, key, pkey->keylen);
134 else
135 ret = crypto_akcipher_set_pub_key(tfm, key, pkey->keylen);
136 if (ret < 0)
137 goto error_free_key;
138
139 len = crypto_akcipher_maxsize(tfm);
140 info->key_size = len * 8;
141 info->max_data_size = len;
142 info->max_sig_size = len;
143 info->max_enc_size = len;
144 info->max_dec_size = len;
145 info->supported_ops = (KEYCTL_SUPPORTS_ENCRYPT |
146 KEYCTL_SUPPORTS_VERIFY);
147 if (pkey->key_is_private)
148 info->supported_ops |= (KEYCTL_SUPPORTS_DECRYPT |
149 KEYCTL_SUPPORTS_SIGN);
150 ret = 0;
151
152 error_free_key:
153 kfree(key);
154 error_free_tfm:
155 crypto_free_akcipher(tfm);
156 pr_devel("<==%s() = %d\n", __func__, ret);
157 return ret;
158 }
159
160 /*
161 * Do encryption, decryption and signing ops.
162 */
software_key_eds_op(struct kernel_pkey_params * params,const void * in,void * out)163 static int software_key_eds_op(struct kernel_pkey_params *params,
164 const void *in, void *out)
165 {
166 const struct public_key *pkey = params->key->payload.data[asym_crypto];
167 struct akcipher_request *req;
168 struct crypto_akcipher *tfm;
169 struct crypto_wait cwait;
170 struct scatterlist in_sg, out_sg;
171 char alg_name[CRYPTO_MAX_ALG_NAME];
172 char *key, *ptr;
173 int ret;
174
175 pr_devel("==>%s()\n", __func__);
176
177 ret = software_key_determine_akcipher(params->encoding,
178 params->hash_algo,
179 pkey, alg_name);
180 if (ret < 0)
181 return ret;
182
183 tfm = crypto_alloc_akcipher(alg_name, 0, 0);
184 if (IS_ERR(tfm))
185 return PTR_ERR(tfm);
186
187 req = akcipher_request_alloc(tfm, GFP_KERNEL);
188 if (!req)
189 goto error_free_tfm;
190
191 key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
192 GFP_KERNEL);
193 if (!key)
194 goto error_free_req;
195
196 memcpy(key, pkey->key, pkey->keylen);
197 ptr = key + pkey->keylen;
198 ptr = pkey_pack_u32(ptr, pkey->algo);
199 ptr = pkey_pack_u32(ptr, pkey->paramlen);
200 memcpy(ptr, pkey->params, pkey->paramlen);
201
202 if (pkey->key_is_private)
203 ret = crypto_akcipher_set_priv_key(tfm, key, pkey->keylen);
204 else
205 ret = crypto_akcipher_set_pub_key(tfm, key, pkey->keylen);
206 if (ret)
207 goto error_free_key;
208
209 sg_init_one(&in_sg, in, params->in_len);
210 sg_init_one(&out_sg, out, params->out_len);
211 akcipher_request_set_crypt(req, &in_sg, &out_sg, params->in_len,
212 params->out_len);
213 crypto_init_wait(&cwait);
214 akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
215 CRYPTO_TFM_REQ_MAY_SLEEP,
216 crypto_req_done, &cwait);
217
218 /* Perform the encryption calculation. */
219 switch (params->op) {
220 case kernel_pkey_encrypt:
221 ret = crypto_akcipher_encrypt(req);
222 break;
223 case kernel_pkey_decrypt:
224 ret = crypto_akcipher_decrypt(req);
225 break;
226 case kernel_pkey_sign:
227 ret = crypto_akcipher_sign(req);
228 break;
229 default:
230 BUG();
231 }
232
233 ret = crypto_wait_req(ret, &cwait);
234 if (ret == 0)
235 ret = req->dst_len;
236
237 error_free_key:
238 kfree(key);
239 error_free_req:
240 akcipher_request_free(req);
241 error_free_tfm:
242 crypto_free_akcipher(tfm);
243 pr_devel("<==%s() = %d\n", __func__, ret);
244 return ret;
245 }
246
247 /*
248 * Verify a signature using a public key.
249 */
public_key_verify_signature(const struct public_key * pkey,const struct public_key_signature * sig)250 int public_key_verify_signature(const struct public_key *pkey,
251 const struct public_key_signature *sig)
252 {
253 struct crypto_wait cwait;
254 struct crypto_akcipher *tfm;
255 struct akcipher_request *req;
256 struct scatterlist src_sg[2];
257 char alg_name[CRYPTO_MAX_ALG_NAME];
258 char *key, *ptr;
259 int ret;
260
261 pr_devel("==>%s()\n", __func__);
262
263 BUG_ON(!pkey);
264 BUG_ON(!sig);
265 BUG_ON(!sig->s);
266
267 ret = software_key_determine_akcipher(sig->encoding,
268 sig->hash_algo,
269 pkey, alg_name);
270 if (ret < 0)
271 return ret;
272
273 tfm = crypto_alloc_akcipher(alg_name, 0, 0);
274 if (IS_ERR(tfm))
275 return PTR_ERR(tfm);
276
277 ret = -ENOMEM;
278 req = akcipher_request_alloc(tfm, GFP_KERNEL);
279 if (!req)
280 goto error_free_tfm;
281
282 key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
283 GFP_KERNEL);
284 if (!key)
285 goto error_free_req;
286
287 memcpy(key, pkey->key, pkey->keylen);
288 ptr = key + pkey->keylen;
289 ptr = pkey_pack_u32(ptr, pkey->algo);
290 ptr = pkey_pack_u32(ptr, pkey->paramlen);
291 memcpy(ptr, pkey->params, pkey->paramlen);
292
293 if (pkey->key_is_private)
294 ret = crypto_akcipher_set_priv_key(tfm, key, pkey->keylen);
295 else
296 ret = crypto_akcipher_set_pub_key(tfm, key, pkey->keylen);
297 if (ret)
298 goto error_free_key;
299
300 sg_init_table(src_sg, 2);
301 sg_set_buf(&src_sg[0], sig->s, sig->s_size);
302 sg_set_buf(&src_sg[1], sig->digest, sig->digest_size);
303 akcipher_request_set_crypt(req, src_sg, NULL, sig->s_size,
304 sig->digest_size);
305 crypto_init_wait(&cwait);
306 akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
307 CRYPTO_TFM_REQ_MAY_SLEEP,
308 crypto_req_done, &cwait);
309 ret = crypto_wait_req(crypto_akcipher_verify(req), &cwait);
310
311 error_free_key:
312 kfree(key);
313 error_free_req:
314 akcipher_request_free(req);
315 error_free_tfm:
316 crypto_free_akcipher(tfm);
317 pr_devel("<==%s() = %d\n", __func__, ret);
318 if (WARN_ON_ONCE(ret > 0))
319 ret = -EINVAL;
320 return ret;
321 }
322 EXPORT_SYMBOL_GPL(public_key_verify_signature);
323
public_key_verify_signature_2(const struct key * key,const struct public_key_signature * sig)324 static int public_key_verify_signature_2(const struct key *key,
325 const struct public_key_signature *sig)
326 {
327 const struct public_key *pk = key->payload.data[asym_crypto];
328 return public_key_verify_signature(pk, sig);
329 }
330
331 /*
332 * Public key algorithm asymmetric key subtype
333 */
334 struct asymmetric_key_subtype public_key_subtype = {
335 .owner = THIS_MODULE,
336 .name = "public_key",
337 .name_len = sizeof("public_key") - 1,
338 .describe = public_key_describe,
339 .destroy = public_key_destroy,
340 .query = software_key_query,
341 .eds_op = software_key_eds_op,
342 .verify_signature = public_key_verify_signature_2,
343 };
344 EXPORT_SYMBOL_GPL(public_key_subtype);
345
