1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* In-software asymmetric public-key crypto subtype
3 *
4 * See Documentation/crypto/asymmetric-keys.rst
5 *
6 * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
7 * Written by David Howells ([email protected])
8 */
9
10 #define pr_fmt(fmt) "PKEY: "fmt
11 #include <crypto/akcipher.h>
12 #include <crypto/public_key.h>
13 #include <crypto/sig.h>
14 #include <keys/asymmetric-subtype.h>
15 #include <linux/asn1.h>
16 #include <linux/err.h>
17 #include <linux/kernel.h>
18 #include <linux/module.h>
19 #include <linux/seq_file.h>
20 #include <linux/slab.h>
21 #include <linux/string.h>
22
23 MODULE_DESCRIPTION("In-software asymmetric public-key subtype");
24 MODULE_AUTHOR("Red Hat, Inc.");
25 MODULE_LICENSE("GPL");
26
27 /*
28 * Provide a part of a description of the key for /proc/keys.
29 */
public_key_describe(const struct key * asymmetric_key,struct seq_file * m)30 static void public_key_describe(const struct key *asymmetric_key,
31 struct seq_file *m)
32 {
33 struct public_key *key = asymmetric_key->payload.data[asym_crypto];
34
35 if (key)
36 seq_printf(m, "%s.%s", key->id_type, key->pkey_algo);
37 }
38
39 /*
40 * Destroy a public key algorithm key.
41 */
public_key_free(struct public_key * key)42 void public_key_free(struct public_key *key)
43 {
44 if (key) {
45 kfree_sensitive(key->key);
46 kfree(key->params);
47 kfree(key);
48 }
49 }
50 EXPORT_SYMBOL_GPL(public_key_free);
51
52 /*
53 * Destroy a public key algorithm key.
54 */
public_key_destroy(void * payload0,void * payload3)55 static void public_key_destroy(void *payload0, void *payload3)
56 {
57 public_key_free(payload0);
58 public_key_signature_free(payload3);
59 }
60
61 /*
62 * Given a public_key, and an encoding and hash_algo to be used for signing
63 * and/or verification with that key, determine the name of the corresponding
64 * akcipher algorithm. Also check that encoding and hash_algo are allowed.
65 */
66 static int
software_key_determine_akcipher(const struct public_key * pkey,const char * encoding,const char * hash_algo,char alg_name[CRYPTO_MAX_ALG_NAME],bool * sig,enum kernel_pkey_operation op)67 software_key_determine_akcipher(const struct public_key *pkey,
68 const char *encoding, const char *hash_algo,
69 char alg_name[CRYPTO_MAX_ALG_NAME], bool *sig,
70 enum kernel_pkey_operation op)
71 {
72 int n;
73
74 *sig = true;
75
76 if (!encoding)
77 return -EINVAL;
78
79 if (strcmp(pkey->pkey_algo, "rsa") == 0) {
80 /*
81 * RSA signatures usually use EMSA-PKCS1-1_5 [RFC3447 sec 8.2].
82 */
83 if (strcmp(encoding, "pkcs1") == 0) {
84 *sig = op == kernel_pkey_sign ||
85 op == kernel_pkey_verify;
86 if (!*sig) {
87 /*
88 * For encrypt/decrypt, hash_algo is not used
89 * but allowed to be set for historic reasons.
90 */
91 n = snprintf(alg_name, CRYPTO_MAX_ALG_NAME,
92 "pkcs1pad(%s)",
93 pkey->pkey_algo);
94 } else {
95 if (!hash_algo)
96 hash_algo = "none";
97 n = snprintf(alg_name, CRYPTO_MAX_ALG_NAME,
98 "pkcs1(%s,%s)",
99 pkey->pkey_algo, hash_algo);
100 }
101 return n >= CRYPTO_MAX_ALG_NAME ? -EINVAL : 0;
102 }
103 if (strcmp(encoding, "raw") != 0)
104 return -EINVAL;
105 /*
106 * Raw RSA cannot differentiate between different hash
107 * algorithms.
108 */
109 if (hash_algo)
110 return -EINVAL;
111 *sig = false;
112 } else if (strncmp(pkey->pkey_algo, "ecdsa", 5) == 0) {
113 if (strcmp(encoding, "x962") != 0 &&
114 strcmp(encoding, "p1363") != 0)
115 return -EINVAL;
116 /*
117 * ECDSA signatures are taken over a raw hash, so they don't
118 * differentiate between different hash algorithms. That means
119 * that the verifier should hard-code a specific hash algorithm.
120 * Unfortunately, in practice ECDSA is used with multiple SHAs,
121 * so we have to allow all of them and not just one.
122 */
123 if (!hash_algo)
124 return -EINVAL;
125 if (strcmp(hash_algo, "sha1") != 0 &&
126 strcmp(hash_algo, "sha224") != 0 &&
127 strcmp(hash_algo, "sha256") != 0 &&
128 strcmp(hash_algo, "sha384") != 0 &&
129 strcmp(hash_algo, "sha512") != 0 &&
130 strcmp(hash_algo, "sha3-256") != 0 &&
131 strcmp(hash_algo, "sha3-384") != 0 &&
132 strcmp(hash_algo, "sha3-512") != 0)
133 return -EINVAL;
134 n = snprintf(alg_name, CRYPTO_MAX_ALG_NAME, "%s(%s)",
135 encoding, pkey->pkey_algo);
136 return n >= CRYPTO_MAX_ALG_NAME ? -EINVAL : 0;
137 } else if (strcmp(pkey->pkey_algo, "ecrdsa") == 0) {
138 if (strcmp(encoding, "raw") != 0)
139 return -EINVAL;
140 if (!hash_algo)
141 return -EINVAL;
142 if (strcmp(hash_algo, "streebog256") != 0 &&
143 strcmp(hash_algo, "streebog512") != 0)
144 return -EINVAL;
145 } else {
146 /* Unknown public key algorithm */
147 return -ENOPKG;
148 }
149 if (strscpy(alg_name, pkey->pkey_algo, CRYPTO_MAX_ALG_NAME) < 0)
150 return -EINVAL;
151 return 0;
152 }
153
pkey_pack_u32(u8 * dst,u32 val)154 static u8 *pkey_pack_u32(u8 *dst, u32 val)
155 {
156 memcpy(dst, &val, sizeof(val));
157 return dst + sizeof(val);
158 }
159
160 /*
161 * Query information about a key.
162 */
software_key_query(const struct kernel_pkey_params * params,struct kernel_pkey_query * info)163 static int software_key_query(const struct kernel_pkey_params *params,
164 struct kernel_pkey_query *info)
165 {
166 struct crypto_akcipher *tfm;
167 struct public_key *pkey = params->key->payload.data[asym_crypto];
168 char alg_name[CRYPTO_MAX_ALG_NAME];
169 struct crypto_sig *sig;
170 u8 *key, *ptr;
171 int ret, len;
172 bool issig;
173
174 ret = software_key_determine_akcipher(pkey, params->encoding,
175 params->hash_algo, alg_name,
176 &issig, kernel_pkey_sign);
177 if (ret < 0)
178 return ret;
179
180 key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
181 GFP_KERNEL);
182 if (!key)
183 return -ENOMEM;
184
185 memcpy(key, pkey->key, pkey->keylen);
186 ptr = key + pkey->keylen;
187 ptr = pkey_pack_u32(ptr, pkey->algo);
188 ptr = pkey_pack_u32(ptr, pkey->paramlen);
189 memcpy(ptr, pkey->params, pkey->paramlen);
190
191 if (issig) {
192 sig = crypto_alloc_sig(alg_name, 0, 0);
193 if (IS_ERR(sig)) {
194 ret = PTR_ERR(sig);
195 goto error_free_key;
196 }
197
198 if (pkey->key_is_private)
199 ret = crypto_sig_set_privkey(sig, key, pkey->keylen);
200 else
201 ret = crypto_sig_set_pubkey(sig, key, pkey->keylen);
202 if (ret < 0)
203 goto error_free_tfm;
204
205 len = crypto_sig_keysize(sig);
206 info->max_sig_size = crypto_sig_maxsize(sig);
207 info->max_data_size = crypto_sig_digestsize(sig);
208
209 info->supported_ops = KEYCTL_SUPPORTS_VERIFY;
210 if (pkey->key_is_private)
211 info->supported_ops |= KEYCTL_SUPPORTS_SIGN;
212
213 if (strcmp(params->encoding, "pkcs1") == 0) {
214 info->supported_ops |= KEYCTL_SUPPORTS_ENCRYPT;
215 if (pkey->key_is_private)
216 info->supported_ops |= KEYCTL_SUPPORTS_DECRYPT;
217 }
218 } else {
219 tfm = crypto_alloc_akcipher(alg_name, 0, 0);
220 if (IS_ERR(tfm)) {
221 ret = PTR_ERR(tfm);
222 goto error_free_key;
223 }
224
225 if (pkey->key_is_private)
226 ret = crypto_akcipher_set_priv_key(tfm, key, pkey->keylen);
227 else
228 ret = crypto_akcipher_set_pub_key(tfm, key, pkey->keylen);
229 if (ret < 0)
230 goto error_free_tfm;
231
232 len = crypto_akcipher_maxsize(tfm);
233 info->max_sig_size = len;
234 info->max_data_size = len;
235
236 info->supported_ops = KEYCTL_SUPPORTS_ENCRYPT;
237 if (pkey->key_is_private)
238 info->supported_ops |= KEYCTL_SUPPORTS_DECRYPT;
239 }
240
241 info->key_size = len * 8;
242 info->max_enc_size = len;
243 info->max_dec_size = len;
244
245 ret = 0;
246
247 error_free_tfm:
248 if (issig)
249 crypto_free_sig(sig);
250 else
251 crypto_free_akcipher(tfm);
252 error_free_key:
253 kfree_sensitive(key);
254 pr_devel("<==%s() = %d\n", __func__, ret);
255 return ret;
256 }
257
258 /*
259 * Do encryption, decryption and signing ops.
260 */
software_key_eds_op(struct kernel_pkey_params * params,const void * in,void * out)261 static int software_key_eds_op(struct kernel_pkey_params *params,
262 const void *in, void *out)
263 {
264 const struct public_key *pkey = params->key->payload.data[asym_crypto];
265 char alg_name[CRYPTO_MAX_ALG_NAME];
266 struct crypto_akcipher *tfm;
267 struct crypto_sig *sig;
268 char *key, *ptr;
269 bool issig;
270 int ksz;
271 int ret;
272
273 pr_devel("==>%s()\n", __func__);
274
275 ret = software_key_determine_akcipher(pkey, params->encoding,
276 params->hash_algo, alg_name,
277 &issig, params->op);
278 if (ret < 0)
279 return ret;
280
281 key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
282 GFP_KERNEL);
283 if (!key)
284 return -ENOMEM;
285
286 memcpy(key, pkey->key, pkey->keylen);
287 ptr = key + pkey->keylen;
288 ptr = pkey_pack_u32(ptr, pkey->algo);
289 ptr = pkey_pack_u32(ptr, pkey->paramlen);
290 memcpy(ptr, pkey->params, pkey->paramlen);
291
292 if (issig) {
293 sig = crypto_alloc_sig(alg_name, 0, 0);
294 if (IS_ERR(sig)) {
295 ret = PTR_ERR(sig);
296 goto error_free_key;
297 }
298
299 if (pkey->key_is_private)
300 ret = crypto_sig_set_privkey(sig, key, pkey->keylen);
301 else
302 ret = crypto_sig_set_pubkey(sig, key, pkey->keylen);
303 if (ret)
304 goto error_free_tfm;
305
306 ksz = crypto_sig_keysize(sig);
307 } else {
308 tfm = crypto_alloc_akcipher(alg_name, 0, 0);
309 if (IS_ERR(tfm)) {
310 ret = PTR_ERR(tfm);
311 goto error_free_key;
312 }
313
314 if (pkey->key_is_private)
315 ret = crypto_akcipher_set_priv_key(tfm, key, pkey->keylen);
316 else
317 ret = crypto_akcipher_set_pub_key(tfm, key, pkey->keylen);
318 if (ret)
319 goto error_free_tfm;
320
321 ksz = crypto_akcipher_maxsize(tfm);
322 }
323
324 ret = -EINVAL;
325
326 /* Perform the encryption calculation. */
327 switch (params->op) {
328 case kernel_pkey_encrypt:
329 if (issig)
330 break;
331 ret = crypto_akcipher_sync_encrypt(tfm, in, params->in_len,
332 out, params->out_len);
333 break;
334 case kernel_pkey_decrypt:
335 if (issig)
336 break;
337 ret = crypto_akcipher_sync_decrypt(tfm, in, params->in_len,
338 out, params->out_len);
339 break;
340 case kernel_pkey_sign:
341 if (!issig)
342 break;
343 ret = crypto_sig_sign(sig, in, params->in_len,
344 out, params->out_len);
345 break;
346 default:
347 BUG();
348 }
349
350 if (ret == 0)
351 ret = ksz;
352
353 error_free_tfm:
354 if (issig)
355 crypto_free_sig(sig);
356 else
357 crypto_free_akcipher(tfm);
358 error_free_key:
359 kfree_sensitive(key);
360 pr_devel("<==%s() = %d\n", __func__, ret);
361 return ret;
362 }
363
364 /*
365 * Verify a signature using a public key.
366 */
public_key_verify_signature(const struct public_key * pkey,const struct public_key_signature * sig)367 int public_key_verify_signature(const struct public_key *pkey,
368 const struct public_key_signature *sig)
369 {
370 char alg_name[CRYPTO_MAX_ALG_NAME];
371 struct crypto_sig *tfm;
372 char *key, *ptr;
373 bool issig;
374 int ret;
375
376 pr_devel("==>%s()\n", __func__);
377
378 BUG_ON(!pkey);
379 BUG_ON(!sig);
380 BUG_ON(!sig->s);
381
382 /*
383 * If the signature specifies a public key algorithm, it *must* match
384 * the key's actual public key algorithm.
385 *
386 * Small exception: ECDSA signatures don't specify the curve, but ECDSA
387 * keys do. So the strings can mismatch slightly in that case:
388 * "ecdsa-nist-*" for the key, but "ecdsa" for the signature.
389 */
390 if (sig->pkey_algo) {
391 if (strcmp(pkey->pkey_algo, sig->pkey_algo) != 0 &&
392 (strncmp(pkey->pkey_algo, "ecdsa-", 6) != 0 ||
393 strcmp(sig->pkey_algo, "ecdsa") != 0))
394 return -EKEYREJECTED;
395 }
396
397 ret = software_key_determine_akcipher(pkey, sig->encoding,
398 sig->hash_algo, alg_name,
399 &issig, kernel_pkey_verify);
400 if (ret < 0)
401 return ret;
402
403 tfm = crypto_alloc_sig(alg_name, 0, 0);
404 if (IS_ERR(tfm))
405 return PTR_ERR(tfm);
406
407 key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
408 GFP_KERNEL);
409 if (!key) {
410 ret = -ENOMEM;
411 goto error_free_tfm;
412 }
413
414 memcpy(key, pkey->key, pkey->keylen);
415 ptr = key + pkey->keylen;
416 ptr = pkey_pack_u32(ptr, pkey->algo);
417 ptr = pkey_pack_u32(ptr, pkey->paramlen);
418 memcpy(ptr, pkey->params, pkey->paramlen);
419
420 if (pkey->key_is_private)
421 ret = crypto_sig_set_privkey(tfm, key, pkey->keylen);
422 else
423 ret = crypto_sig_set_pubkey(tfm, key, pkey->keylen);
424 if (ret)
425 goto error_free_key;
426
427 ret = crypto_sig_verify(tfm, sig->s, sig->s_size,
428 sig->digest, sig->digest_size);
429
430 error_free_key:
431 kfree_sensitive(key);
432 error_free_tfm:
433 crypto_free_sig(tfm);
434 pr_devel("<==%s() = %d\n", __func__, ret);
435 if (WARN_ON_ONCE(ret > 0))
436 ret = -EINVAL;
437 return ret;
438 }
439 EXPORT_SYMBOL_GPL(public_key_verify_signature);
440
public_key_verify_signature_2(const struct key * key,const struct public_key_signature * sig)441 static int public_key_verify_signature_2(const struct key *key,
442 const struct public_key_signature *sig)
443 {
444 const struct public_key *pk = key->payload.data[asym_crypto];
445 return public_key_verify_signature(pk, sig);
446 }
447
448 /*
449 * Public key algorithm asymmetric key subtype
450 */
451 struct asymmetric_key_subtype public_key_subtype = {
452 .owner = THIS_MODULE,
453 .name = "public_key",
454 .name_len = sizeof("public_key") - 1,
455 .describe = public_key_describe,
456 .destroy = public_key_destroy,
457 .query = software_key_query,
458 .eds_op = software_key_eds_op,
459 .verify_signature = public_key_verify_signature_2,
460 };
461 EXPORT_SYMBOL_GPL(public_key_subtype);
462