public_key.c 9.9 KB

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  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. #define pr_fmt(fmt) "PKEY: "fmt
  10. #include <linux/module.h>
  11. #include <linux/export.h>
  12. #include <linux/kernel.h>
  13. #include <linux/slab.h>
  14. #include <linux/seq_file.h>
  15. #include <linux/scatterlist.h>
  16. #include <keys/asymmetric-subtype.h>
  17. #include <crypto/public_key.h>
  18. #include <crypto/akcipher.h>
  19. #include <crypto/sm2.h>
  20. #include <crypto/sm3_base.h>
  21. MODULE_DESCRIPTION("In-software asymmetric public-key subtype");
  22. MODULE_AUTHOR("Red Hat, Inc.");
  23. MODULE_LICENSE("GPL");
  24. /*
  25. * Provide a part of a description of the key for /proc/keys.
  26. */
  27. static void public_key_describe(const struct key *asymmetric_key,
  28. struct seq_file *m)
  29. {
  30. struct public_key *key = asymmetric_key->payload.data[asym_crypto];
  31. if (key)
  32. seq_printf(m, "%s.%s", key->id_type, key->pkey_algo);
  33. }
  34. /*
  35. * Destroy a public key algorithm key.
  36. */
  37. void public_key_free(struct public_key *key)
  38. {
  39. if (key) {
  40. kfree(key->key);
  41. kfree(key->params);
  42. kfree(key);
  43. }
  44. }
  45. EXPORT_SYMBOL_GPL(public_key_free);
  46. /*
  47. * Destroy a public key algorithm key.
  48. */
  49. static void public_key_destroy(void *payload0, void *payload3)
  50. {
  51. public_key_free(payload0);
  52. public_key_signature_free(payload3);
  53. }
  54. /*
  55. * Determine the crypto algorithm name.
  56. */
  57. static
  58. int software_key_determine_akcipher(const char *encoding,
  59. const char *hash_algo,
  60. const struct public_key *pkey,
  61. char alg_name[CRYPTO_MAX_ALG_NAME])
  62. {
  63. int n;
  64. if (strcmp(encoding, "pkcs1") == 0) {
  65. /* The data wangled by the RSA algorithm is typically padded
  66. * and encoded in some manner, such as EMSA-PKCS1-1_5 [RFC3447
  67. * sec 8.2].
  68. */
  69. if (!hash_algo)
  70. n = snprintf(alg_name, CRYPTO_MAX_ALG_NAME,
  71. "pkcs1pad(%s)",
  72. pkey->pkey_algo);
  73. else
  74. n = snprintf(alg_name, CRYPTO_MAX_ALG_NAME,
  75. "pkcs1pad(%s,%s)",
  76. pkey->pkey_algo, hash_algo);
  77. return n >= CRYPTO_MAX_ALG_NAME ? -EINVAL : 0;
  78. }
  79. if (strcmp(encoding, "raw") == 0) {
  80. strcpy(alg_name, pkey->pkey_algo);
  81. return 0;
  82. }
  83. return -ENOPKG;
  84. }
  85. static u8 *pkey_pack_u32(u8 *dst, u32 val)
  86. {
  87. memcpy(dst, &val, sizeof(val));
  88. return dst + sizeof(val);
  89. }
  90. /*
  91. * Query information about a key.
  92. */
  93. static int software_key_query(const struct kernel_pkey_params *params,
  94. struct kernel_pkey_query *info)
  95. {
  96. struct crypto_akcipher *tfm;
  97. struct public_key *pkey = params->key->payload.data[asym_crypto];
  98. char alg_name[CRYPTO_MAX_ALG_NAME];
  99. u8 *key, *ptr;
  100. int ret, len;
  101. ret = software_key_determine_akcipher(params->encoding,
  102. params->hash_algo,
  103. pkey, alg_name);
  104. if (ret < 0)
  105. return ret;
  106. tfm = crypto_alloc_akcipher(alg_name, 0, 0);
  107. if (IS_ERR(tfm))
  108. return PTR_ERR(tfm);
  109. ret = -ENOMEM;
  110. key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
  111. GFP_KERNEL);
  112. if (!key)
  113. goto error_free_tfm;
  114. memcpy(key, pkey->key, pkey->keylen);
  115. ptr = key + pkey->keylen;
  116. ptr = pkey_pack_u32(ptr, pkey->algo);
  117. ptr = pkey_pack_u32(ptr, pkey->paramlen);
  118. memcpy(ptr, pkey->params, pkey->paramlen);
  119. if (pkey->key_is_private)
  120. ret = crypto_akcipher_set_priv_key(tfm, key, pkey->keylen);
  121. else
  122. ret = crypto_akcipher_set_pub_key(tfm, key, pkey->keylen);
  123. if (ret < 0)
  124. goto error_free_key;
  125. len = crypto_akcipher_maxsize(tfm);
  126. info->key_size = len * 8;
  127. info->max_data_size = len;
  128. info->max_sig_size = len;
  129. info->max_enc_size = len;
  130. info->max_dec_size = len;
  131. info->supported_ops = (KEYCTL_SUPPORTS_ENCRYPT |
  132. KEYCTL_SUPPORTS_VERIFY);
  133. if (pkey->key_is_private)
  134. info->supported_ops |= (KEYCTL_SUPPORTS_DECRYPT |
  135. KEYCTL_SUPPORTS_SIGN);
  136. ret = 0;
  137. error_free_key:
  138. kfree(key);
  139. error_free_tfm:
  140. crypto_free_akcipher(tfm);
  141. pr_devel("<==%s() = %d\n", __func__, ret);
  142. return ret;
  143. }
  144. /*
  145. * Do encryption, decryption and signing ops.
  146. */
  147. static int software_key_eds_op(struct kernel_pkey_params *params,
  148. const void *in, void *out)
  149. {
  150. const struct public_key *pkey = params->key->payload.data[asym_crypto];
  151. struct akcipher_request *req;
  152. struct crypto_akcipher *tfm;
  153. struct crypto_wait cwait;
  154. struct scatterlist in_sg, out_sg;
  155. char alg_name[CRYPTO_MAX_ALG_NAME];
  156. char *key, *ptr;
  157. int ret;
  158. pr_devel("==>%s()\n", __func__);
  159. ret = software_key_determine_akcipher(params->encoding,
  160. params->hash_algo,
  161. pkey, alg_name);
  162. if (ret < 0)
  163. return ret;
  164. tfm = crypto_alloc_akcipher(alg_name, 0, 0);
  165. if (IS_ERR(tfm))
  166. return PTR_ERR(tfm);
  167. ret = -ENOMEM;
  168. req = akcipher_request_alloc(tfm, GFP_KERNEL);
  169. if (!req)
  170. goto error_free_tfm;
  171. key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
  172. GFP_KERNEL);
  173. if (!key)
  174. goto error_free_req;
  175. memcpy(key, pkey->key, pkey->keylen);
  176. ptr = key + pkey->keylen;
  177. ptr = pkey_pack_u32(ptr, pkey->algo);
  178. ptr = pkey_pack_u32(ptr, pkey->paramlen);
  179. memcpy(ptr, pkey->params, pkey->paramlen);
  180. if (pkey->key_is_private)
  181. ret = crypto_akcipher_set_priv_key(tfm, key, pkey->keylen);
  182. else
  183. ret = crypto_akcipher_set_pub_key(tfm, key, pkey->keylen);
  184. if (ret)
  185. goto error_free_key;
  186. sg_init_one(&in_sg, in, params->in_len);
  187. sg_init_one(&out_sg, out, params->out_len);
  188. akcipher_request_set_crypt(req, &in_sg, &out_sg, params->in_len,
  189. params->out_len);
  190. crypto_init_wait(&cwait);
  191. akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
  192. CRYPTO_TFM_REQ_MAY_SLEEP,
  193. crypto_req_done, &cwait);
  194. /* Perform the encryption calculation. */
  195. switch (params->op) {
  196. case kernel_pkey_encrypt:
  197. ret = crypto_akcipher_encrypt(req);
  198. break;
  199. case kernel_pkey_decrypt:
  200. ret = crypto_akcipher_decrypt(req);
  201. break;
  202. case kernel_pkey_sign:
  203. ret = crypto_akcipher_sign(req);
  204. break;
  205. default:
  206. BUG();
  207. }
  208. ret = crypto_wait_req(ret, &cwait);
  209. if (ret == 0)
  210. ret = req->dst_len;
  211. error_free_key:
  212. kfree(key);
  213. error_free_req:
  214. akcipher_request_free(req);
  215. error_free_tfm:
  216. crypto_free_akcipher(tfm);
  217. pr_devel("<==%s() = %d\n", __func__, ret);
  218. return ret;
  219. }
  220. #if IS_REACHABLE(CONFIG_CRYPTO_SM2)
  221. static int cert_sig_digest_update(const struct public_key_signature *sig,
  222. struct crypto_akcipher *tfm_pkey)
  223. {
  224. struct crypto_shash *tfm;
  225. struct shash_desc *desc;
  226. size_t desc_size;
  227. unsigned char dgst[SM3_DIGEST_SIZE];
  228. int ret;
  229. BUG_ON(!sig->data);
  230. ret = sm2_compute_z_digest(tfm_pkey, SM2_DEFAULT_USERID,
  231. SM2_DEFAULT_USERID_LEN, dgst);
  232. if (ret)
  233. return ret;
  234. tfm = crypto_alloc_shash(sig->hash_algo, 0, 0);
  235. if (IS_ERR(tfm))
  236. return PTR_ERR(tfm);
  237. desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
  238. desc = kzalloc(desc_size, GFP_KERNEL);
  239. if (!desc) {
  240. ret = -ENOMEM;
  241. goto error_free_tfm;
  242. }
  243. desc->tfm = tfm;
  244. ret = crypto_shash_init(desc);
  245. if (ret < 0)
  246. goto error_free_desc;
  247. ret = crypto_shash_update(desc, dgst, SM3_DIGEST_SIZE);
  248. if (ret < 0)
  249. goto error_free_desc;
  250. ret = crypto_shash_finup(desc, sig->data, sig->data_size, sig->digest);
  251. error_free_desc:
  252. kfree(desc);
  253. error_free_tfm:
  254. crypto_free_shash(tfm);
  255. return ret;
  256. }
  257. #else
  258. static inline int cert_sig_digest_update(
  259. const struct public_key_signature *sig,
  260. struct crypto_akcipher *tfm_pkey)
  261. {
  262. return -ENOTSUPP;
  263. }
  264. #endif /* ! IS_REACHABLE(CONFIG_CRYPTO_SM2) */
  265. /*
  266. * Verify a signature using a public key.
  267. */
  268. int public_key_verify_signature(const struct public_key *pkey,
  269. const struct public_key_signature *sig)
  270. {
  271. struct crypto_wait cwait;
  272. struct crypto_akcipher *tfm;
  273. struct akcipher_request *req;
  274. struct scatterlist src_sg[2];
  275. char alg_name[CRYPTO_MAX_ALG_NAME];
  276. char *key, *ptr;
  277. int ret;
  278. pr_devel("==>%s()\n", __func__);
  279. BUG_ON(!pkey);
  280. BUG_ON(!sig);
  281. BUG_ON(!sig->s);
  282. ret = software_key_determine_akcipher(sig->encoding,
  283. sig->hash_algo,
  284. pkey, alg_name);
  285. if (ret < 0)
  286. return ret;
  287. tfm = crypto_alloc_akcipher(alg_name, 0, 0);
  288. if (IS_ERR(tfm))
  289. return PTR_ERR(tfm);
  290. ret = -ENOMEM;
  291. req = akcipher_request_alloc(tfm, GFP_KERNEL);
  292. if (!req)
  293. goto error_free_tfm;
  294. key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
  295. GFP_KERNEL);
  296. if (!key)
  297. goto error_free_req;
  298. memcpy(key, pkey->key, pkey->keylen);
  299. ptr = key + pkey->keylen;
  300. ptr = pkey_pack_u32(ptr, pkey->algo);
  301. ptr = pkey_pack_u32(ptr, pkey->paramlen);
  302. memcpy(ptr, pkey->params, pkey->paramlen);
  303. if (pkey->key_is_private)
  304. ret = crypto_akcipher_set_priv_key(tfm, key, pkey->keylen);
  305. else
  306. ret = crypto_akcipher_set_pub_key(tfm, key, pkey->keylen);
  307. if (ret)
  308. goto error_free_key;
  309. if (sig->pkey_algo && strcmp(sig->pkey_algo, "sm2") == 0 &&
  310. sig->data_size) {
  311. ret = cert_sig_digest_update(sig, tfm);
  312. if (ret)
  313. goto error_free_key;
  314. }
  315. sg_init_table(src_sg, 2);
  316. sg_set_buf(&src_sg[0], sig->s, sig->s_size);
  317. sg_set_buf(&src_sg[1], sig->digest, sig->digest_size);
  318. akcipher_request_set_crypt(req, src_sg, NULL, sig->s_size,
  319. sig->digest_size);
  320. crypto_init_wait(&cwait);
  321. akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
  322. CRYPTO_TFM_REQ_MAY_SLEEP,
  323. crypto_req_done, &cwait);
  324. ret = crypto_wait_req(crypto_akcipher_verify(req), &cwait);
  325. error_free_key:
  326. kfree(key);
  327. error_free_req:
  328. akcipher_request_free(req);
  329. error_free_tfm:
  330. crypto_free_akcipher(tfm);
  331. pr_devel("<==%s() = %d\n", __func__, ret);
  332. if (WARN_ON_ONCE(ret > 0))
  333. ret = -EINVAL;
  334. return ret;
  335. }
  336. EXPORT_SYMBOL_GPL(public_key_verify_signature);
  337. static int public_key_verify_signature_2(const struct key *key,
  338. const struct public_key_signature *sig)
  339. {
  340. const struct public_key *pk = key->payload.data[asym_crypto];
  341. return public_key_verify_signature(pk, sig);
  342. }
  343. /*
  344. * Public key algorithm asymmetric key subtype
  345. */
  346. struct asymmetric_key_subtype public_key_subtype = {
  347. .owner = THIS_MODULE,
  348. .name = "public_key",
  349. .name_len = sizeof("public_key") - 1,
  350. .describe = public_key_describe,
  351. .destroy = public_key_destroy,
  352. .query = software_key_query,
  353. .eds_op = software_key_eds_op,
  354. .verify_signature = public_key_verify_signature_2,
  355. };
  356. EXPORT_SYMBOL_GPL(public_key_subtype);