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 (dhowells@redhat.com)
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
23MODULE_DESCRIPTION("In-software asymmetric public-key subtype");
24MODULE_AUTHOR("Red Hat, Inc.");
25MODULE_LICENSE("GPL");
26
27/*
28 * Provide a part of a description of the key for /proc/keys.
29 */
30static 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, fmt: "%s.%s", key->id_type, key->pkey_algo);
37}
38
39/*
40 * Destroy a public key algorithm key.
41 */
42void public_key_free(struct public_key *key)
43{
44 if (key) {
45 kfree_sensitive(objp: key->key);
46 kfree(objp: key->params);
47 kfree(objp: key);
48 }
49}
50EXPORT_SYMBOL_GPL(public_key_free);
51
52/*
53 * Destroy a public key algorithm key.
54 */
55static void public_key_destroy(void *payload0, void *payload3)
56{
57 public_key_free(payload0);
58 public_key_signature_free(sig: 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 */
66static int
67software_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 (!hash_algo) {
87 n = snprintf(buf: alg_name, CRYPTO_MAX_ALG_NAME,
88 fmt: "pkcs1pad(%s)",
89 pkey->pkey_algo);
90 } else {
91 n = snprintf(buf: alg_name, CRYPTO_MAX_ALG_NAME,
92 fmt: "pkcs1pad(%s,%s)",
93 pkey->pkey_algo, hash_algo);
94 }
95 return n >= CRYPTO_MAX_ALG_NAME ? -EINVAL : 0;
96 }
97 if (strcmp(encoding, "raw") != 0)
98 return -EINVAL;
99 /*
100 * Raw RSA cannot differentiate between different hash
101 * algorithms.
102 */
103 if (hash_algo)
104 return -EINVAL;
105 *sig = false;
106 } else if (strncmp(pkey->pkey_algo, "ecdsa", 5) == 0) {
107 if (strcmp(encoding, "x962") != 0)
108 return -EINVAL;
109 /*
110 * ECDSA signatures are taken over a raw hash, so they don't
111 * differentiate between different hash algorithms. That means
112 * that the verifier should hard-code a specific hash algorithm.
113 * Unfortunately, in practice ECDSA is used with multiple SHAs,
114 * so we have to allow all of them and not just one.
115 */
116 if (!hash_algo)
117 return -EINVAL;
118 if (strcmp(hash_algo, "sha224") != 0 &&
119 strcmp(hash_algo, "sha256") != 0 &&
120 strcmp(hash_algo, "sha384") != 0 &&
121 strcmp(hash_algo, "sha512") != 0 &&
122 strcmp(hash_algo, "sha3-256") != 0 &&
123 strcmp(hash_algo, "sha3-384") != 0 &&
124 strcmp(hash_algo, "sha3-512") != 0)
125 return -EINVAL;
126 } else if (strcmp(pkey->pkey_algo, "sm2") == 0) {
127 if (strcmp(encoding, "raw") != 0)
128 return -EINVAL;
129 if (!hash_algo)
130 return -EINVAL;
131 if (strcmp(hash_algo, "sm3") != 0)
132 return -EINVAL;
133 } else if (strcmp(pkey->pkey_algo, "ecrdsa") == 0) {
134 if (strcmp(encoding, "raw") != 0)
135 return -EINVAL;
136 if (!hash_algo)
137 return -EINVAL;
138 if (strcmp(hash_algo, "streebog256") != 0 &&
139 strcmp(hash_algo, "streebog512") != 0)
140 return -EINVAL;
141 } else {
142 /* Unknown public key algorithm */
143 return -ENOPKG;
144 }
145 if (strscpy(p: alg_name, q: pkey->pkey_algo, CRYPTO_MAX_ALG_NAME) < 0)
146 return -EINVAL;
147 return 0;
148}
149
150static u8 *pkey_pack_u32(u8 *dst, u32 val)
151{
152 memcpy(dst, &val, sizeof(val));
153 return dst + sizeof(val);
154}
155
156/*
157 * Query information about a key.
158 */
159static int software_key_query(const struct kernel_pkey_params *params,
160 struct kernel_pkey_query *info)
161{
162 struct crypto_akcipher *tfm;
163 struct public_key *pkey = params->key->payload.data[asym_crypto];
164 char alg_name[CRYPTO_MAX_ALG_NAME];
165 struct crypto_sig *sig;
166 u8 *key, *ptr;
167 int ret, len;
168 bool issig;
169
170 ret = software_key_determine_akcipher(pkey, encoding: params->encoding,
171 hash_algo: params->hash_algo, alg_name,
172 sig: &issig, op: kernel_pkey_sign);
173 if (ret < 0)
174 return ret;
175
176 key = kmalloc(size: pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
177 GFP_KERNEL);
178 if (!key)
179 return -ENOMEM;
180
181 memcpy(key, pkey->key, pkey->keylen);
182 ptr = key + pkey->keylen;
183 ptr = pkey_pack_u32(dst: ptr, val: pkey->algo);
184 ptr = pkey_pack_u32(dst: ptr, val: pkey->paramlen);
185 memcpy(ptr, pkey->params, pkey->paramlen);
186
187 if (issig) {
188 sig = crypto_alloc_sig(alg_name, type: 0, mask: 0);
189 if (IS_ERR(ptr: sig)) {
190 ret = PTR_ERR(ptr: sig);
191 goto error_free_key;
192 }
193
194 if (pkey->key_is_private)
195 ret = crypto_sig_set_privkey(tfm: sig, key, keylen: pkey->keylen);
196 else
197 ret = crypto_sig_set_pubkey(tfm: sig, key, keylen: pkey->keylen);
198 if (ret < 0)
199 goto error_free_tfm;
200
201 len = crypto_sig_maxsize(tfm: sig);
202
203 info->supported_ops = KEYCTL_SUPPORTS_VERIFY;
204 if (pkey->key_is_private)
205 info->supported_ops |= KEYCTL_SUPPORTS_SIGN;
206
207 if (strcmp(params->encoding, "pkcs1") == 0) {
208 info->supported_ops |= KEYCTL_SUPPORTS_ENCRYPT;
209 if (pkey->key_is_private)
210 info->supported_ops |= KEYCTL_SUPPORTS_DECRYPT;
211 }
212 } else {
213 tfm = crypto_alloc_akcipher(alg_name, type: 0, mask: 0);
214 if (IS_ERR(ptr: tfm)) {
215 ret = PTR_ERR(ptr: tfm);
216 goto error_free_key;
217 }
218
219 if (pkey->key_is_private)
220 ret = crypto_akcipher_set_priv_key(tfm, key, keylen: pkey->keylen);
221 else
222 ret = crypto_akcipher_set_pub_key(tfm, key, keylen: pkey->keylen);
223 if (ret < 0)
224 goto error_free_tfm;
225
226 len = crypto_akcipher_maxsize(tfm);
227
228 info->supported_ops = KEYCTL_SUPPORTS_ENCRYPT;
229 if (pkey->key_is_private)
230 info->supported_ops |= KEYCTL_SUPPORTS_DECRYPT;
231 }
232
233 info->key_size = len * 8;
234
235 if (strncmp(pkey->pkey_algo, "ecdsa", 5) == 0) {
236 /*
237 * ECDSA key sizes are much smaller than RSA, and thus could
238 * operate on (hashed) inputs that are larger than key size.
239 * For example SHA384-hashed input used with secp256r1
240 * based keys. Set max_data_size to be at least as large as
241 * the largest supported hash size (SHA512)
242 */
243 info->max_data_size = 64;
244
245 /*
246 * Verify takes ECDSA-Sig (described in RFC 5480) as input,
247 * which is actually 2 'key_size'-bit integers encoded in
248 * ASN.1. Account for the ASN.1 encoding overhead here.
249 */
250 info->max_sig_size = 2 * (len + 3) + 2;
251 } else {
252 info->max_data_size = len;
253 info->max_sig_size = len;
254 }
255
256 info->max_enc_size = len;
257 info->max_dec_size = len;
258
259 ret = 0;
260
261error_free_tfm:
262 if (issig)
263 crypto_free_sig(tfm: sig);
264 else
265 crypto_free_akcipher(tfm);
266error_free_key:
267 kfree_sensitive(objp: key);
268 pr_devel("<==%s() = %d\n", __func__, ret);
269 return ret;
270}
271
272/*
273 * Do encryption, decryption and signing ops.
274 */
275static int software_key_eds_op(struct kernel_pkey_params *params,
276 const void *in, void *out)
277{
278 const struct public_key *pkey = params->key->payload.data[asym_crypto];
279 char alg_name[CRYPTO_MAX_ALG_NAME];
280 struct crypto_akcipher *tfm;
281 struct crypto_sig *sig;
282 char *key, *ptr;
283 bool issig;
284 int ksz;
285 int ret;
286
287 pr_devel("==>%s()\n", __func__);
288
289 ret = software_key_determine_akcipher(pkey, encoding: params->encoding,
290 hash_algo: params->hash_algo, alg_name,
291 sig: &issig, op: params->op);
292 if (ret < 0)
293 return ret;
294
295 key = kmalloc(size: pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
296 GFP_KERNEL);
297 if (!key)
298 return -ENOMEM;
299
300 memcpy(key, pkey->key, pkey->keylen);
301 ptr = key + pkey->keylen;
302 ptr = pkey_pack_u32(dst: ptr, val: pkey->algo);
303 ptr = pkey_pack_u32(dst: ptr, val: pkey->paramlen);
304 memcpy(ptr, pkey->params, pkey->paramlen);
305
306 if (issig) {
307 sig = crypto_alloc_sig(alg_name, type: 0, mask: 0);
308 if (IS_ERR(ptr: sig)) {
309 ret = PTR_ERR(ptr: sig);
310 goto error_free_key;
311 }
312
313 if (pkey->key_is_private)
314 ret = crypto_sig_set_privkey(tfm: sig, key, keylen: pkey->keylen);
315 else
316 ret = crypto_sig_set_pubkey(tfm: sig, key, keylen: pkey->keylen);
317 if (ret)
318 goto error_free_tfm;
319
320 ksz = crypto_sig_maxsize(tfm: sig);
321 } else {
322 tfm = crypto_alloc_akcipher(alg_name, type: 0, mask: 0);
323 if (IS_ERR(ptr: tfm)) {
324 ret = PTR_ERR(ptr: tfm);
325 goto error_free_key;
326 }
327
328 if (pkey->key_is_private)
329 ret = crypto_akcipher_set_priv_key(tfm, key, keylen: pkey->keylen);
330 else
331 ret = crypto_akcipher_set_pub_key(tfm, key, keylen: pkey->keylen);
332 if (ret)
333 goto error_free_tfm;
334
335 ksz = crypto_akcipher_maxsize(tfm);
336 }
337
338 ret = -EINVAL;
339
340 /* Perform the encryption calculation. */
341 switch (params->op) {
342 case kernel_pkey_encrypt:
343 if (issig)
344 break;
345 ret = crypto_akcipher_sync_encrypt(tfm, src: in, slen: params->in_len,
346 dst: out, dlen: params->out_len);
347 break;
348 case kernel_pkey_decrypt:
349 if (issig)
350 break;
351 ret = crypto_akcipher_sync_decrypt(tfm, src: in, slen: params->in_len,
352 dst: out, dlen: params->out_len);
353 break;
354 case kernel_pkey_sign:
355 if (!issig)
356 break;
357 ret = crypto_sig_sign(tfm: sig, src: in, slen: params->in_len,
358 dst: out, dlen: params->out_len);
359 break;
360 default:
361 BUG();
362 }
363
364 if (ret == 0)
365 ret = ksz;
366
367error_free_tfm:
368 if (issig)
369 crypto_free_sig(tfm: sig);
370 else
371 crypto_free_akcipher(tfm);
372error_free_key:
373 kfree_sensitive(objp: key);
374 pr_devel("<==%s() = %d\n", __func__, ret);
375 return ret;
376}
377
378/*
379 * Verify a signature using a public key.
380 */
381int public_key_verify_signature(const struct public_key *pkey,
382 const struct public_key_signature *sig)
383{
384 char alg_name[CRYPTO_MAX_ALG_NAME];
385 struct crypto_sig *tfm;
386 char *key, *ptr;
387 bool issig;
388 int ret;
389
390 pr_devel("==>%s()\n", __func__);
391
392 BUG_ON(!pkey);
393 BUG_ON(!sig);
394 BUG_ON(!sig->s);
395
396 /*
397 * If the signature specifies a public key algorithm, it *must* match
398 * the key's actual public key algorithm.
399 *
400 * Small exception: ECDSA signatures don't specify the curve, but ECDSA
401 * keys do. So the strings can mismatch slightly in that case:
402 * "ecdsa-nist-*" for the key, but "ecdsa" for the signature.
403 */
404 if (sig->pkey_algo) {
405 if (strcmp(pkey->pkey_algo, sig->pkey_algo) != 0 &&
406 (strncmp(pkey->pkey_algo, "ecdsa-", 6) != 0 ||
407 strcmp(sig->pkey_algo, "ecdsa") != 0))
408 return -EKEYREJECTED;
409 }
410
411 ret = software_key_determine_akcipher(pkey, encoding: sig->encoding,
412 hash_algo: sig->hash_algo, alg_name,
413 sig: &issig, op: kernel_pkey_verify);
414 if (ret < 0)
415 return ret;
416
417 tfm = crypto_alloc_sig(alg_name, type: 0, mask: 0);
418 if (IS_ERR(ptr: tfm))
419 return PTR_ERR(ptr: tfm);
420
421 key = kmalloc(size: pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
422 GFP_KERNEL);
423 if (!key) {
424 ret = -ENOMEM;
425 goto error_free_tfm;
426 }
427
428 memcpy(key, pkey->key, pkey->keylen);
429 ptr = key + pkey->keylen;
430 ptr = pkey_pack_u32(dst: ptr, val: pkey->algo);
431 ptr = pkey_pack_u32(dst: ptr, val: pkey->paramlen);
432 memcpy(ptr, pkey->params, pkey->paramlen);
433
434 if (pkey->key_is_private)
435 ret = crypto_sig_set_privkey(tfm, key, keylen: pkey->keylen);
436 else
437 ret = crypto_sig_set_pubkey(tfm, key, keylen: pkey->keylen);
438 if (ret)
439 goto error_free_key;
440
441 ret = crypto_sig_verify(tfm, src: sig->s, slen: sig->s_size,
442 digest: sig->digest, dlen: sig->digest_size);
443
444error_free_key:
445 kfree_sensitive(objp: key);
446error_free_tfm:
447 crypto_free_sig(tfm);
448 pr_devel("<==%s() = %d\n", __func__, ret);
449 if (WARN_ON_ONCE(ret > 0))
450 ret = -EINVAL;
451 return ret;
452}
453EXPORT_SYMBOL_GPL(public_key_verify_signature);
454
455static int public_key_verify_signature_2(const struct key *key,
456 const struct public_key_signature *sig)
457{
458 const struct public_key *pk = key->payload.data[asym_crypto];
459 return public_key_verify_signature(pk, sig);
460}
461
462/*
463 * Public key algorithm asymmetric key subtype
464 */
465struct asymmetric_key_subtype public_key_subtype = {
466 .owner = THIS_MODULE,
467 .name = "public_key",
468 .name_len = sizeof("public_key") - 1,
469 .describe = public_key_describe,
470 .destroy = public_key_destroy,
471 .query = software_key_query,
472 .eds_op = software_key_eds_op,
473 .verify_signature = public_key_verify_signature_2,
474};
475EXPORT_SYMBOL_GPL(public_key_subtype);
476

source code of linux/crypto/asymmetric_keys/public_key.c