x509_public_key.c 7.1 KB

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  1. // SPDX-License-Identifier: GPL-2.0-or-later
  2. /* Instantiate a public key crypto key from an X.509 Certificate
  3. *
  4. * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
  5. * Written by David Howells (dhowells@redhat.com)
  6. */
  7. #define pr_fmt(fmt) "X.509: "fmt
  8. #ifdef __UBOOT__
  9. #include <common.h>
  10. #include <image.h>
  11. #include <dm/devres.h>
  12. #include <linux/compat.h>
  13. #include <linux/err.h>
  14. #include <linux/errno.h>
  15. #else
  16. #include <linux/module.h>
  17. #endif
  18. #include <linux/kernel.h>
  19. #ifdef __UBOOT__
  20. #include <crypto/x509_parser.h>
  21. #include <u-boot/rsa-checksum.h>
  22. #else
  23. #include <linux/slab.h>
  24. #include <keys/asymmetric-subtype.h>
  25. #include <keys/asymmetric-parser.h>
  26. #include <keys/system_keyring.h>
  27. #include <crypto/hash.h>
  28. #include "asymmetric_keys.h"
  29. #include "x509_parser.h"
  30. #endif
  31. /*
  32. * Set up the signature parameters in an X.509 certificate. This involves
  33. * digesting the signed data and extracting the signature.
  34. */
  35. int x509_get_sig_params(struct x509_certificate *cert)
  36. {
  37. struct public_key_signature *sig = cert->sig;
  38. #ifdef __UBOOT__
  39. struct image_region region;
  40. #else
  41. struct crypto_shash *tfm;
  42. struct shash_desc *desc;
  43. size_t desc_size;
  44. #endif
  45. int ret;
  46. pr_devel("==>%s()\n", __func__);
  47. if (!cert->pub->pkey_algo)
  48. cert->unsupported_key = true;
  49. if (!sig->pkey_algo)
  50. cert->unsupported_sig = true;
  51. /* We check the hash if we can - even if we can't then verify it */
  52. if (!sig->hash_algo) {
  53. cert->unsupported_sig = true;
  54. return 0;
  55. }
  56. sig->s = kmemdup(cert->raw_sig, cert->raw_sig_size, GFP_KERNEL);
  57. if (!sig->s)
  58. return -ENOMEM;
  59. sig->s_size = cert->raw_sig_size;
  60. #ifdef __UBOOT__
  61. if (!sig->hash_algo)
  62. return -ENOPKG;
  63. if (!strcmp(sig->hash_algo, "sha256"))
  64. sig->digest_size = SHA256_SUM_LEN;
  65. else if (!strcmp(sig->hash_algo, "sha1"))
  66. sig->digest_size = SHA1_SUM_LEN;
  67. else
  68. return -ENOPKG;
  69. sig->digest = calloc(1, sig->digest_size);
  70. if (!sig->digest)
  71. return -ENOMEM;
  72. region.data = cert->tbs;
  73. region.size = cert->tbs_size;
  74. hash_calculate(sig->hash_algo, &region, 1, sig->digest);
  75. /* TODO: is_hash_blacklisted()? */
  76. ret = 0;
  77. #else
  78. /* Allocate the hashing algorithm we're going to need and find out how
  79. * big the hash operational data will be.
  80. */
  81. tfm = crypto_alloc_shash(sig->hash_algo, 0, 0);
  82. if (IS_ERR(tfm)) {
  83. if (PTR_ERR(tfm) == -ENOENT) {
  84. cert->unsupported_sig = true;
  85. return 0;
  86. }
  87. return PTR_ERR(tfm);
  88. }
  89. desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
  90. sig->digest_size = crypto_shash_digestsize(tfm);
  91. ret = -ENOMEM;
  92. sig->digest = kmalloc(sig->digest_size, GFP_KERNEL);
  93. if (!sig->digest)
  94. goto error;
  95. desc = kzalloc(desc_size, GFP_KERNEL);
  96. if (!desc)
  97. goto error;
  98. desc->tfm = tfm;
  99. ret = crypto_shash_digest(desc, cert->tbs, cert->tbs_size, sig->digest);
  100. if (ret < 0)
  101. goto error_2;
  102. ret = is_hash_blacklisted(sig->digest, sig->digest_size, "tbs");
  103. if (ret == -EKEYREJECTED) {
  104. pr_err("Cert %*phN is blacklisted\n",
  105. sig->digest_size, sig->digest);
  106. cert->blacklisted = true;
  107. ret = 0;
  108. }
  109. error_2:
  110. kfree(desc);
  111. error:
  112. crypto_free_shash(tfm);
  113. #endif /* __UBOOT__ */
  114. pr_devel("<==%s() = %d\n", __func__, ret);
  115. return ret;
  116. }
  117. /*
  118. * Check for self-signedness in an X.509 cert and if found, check the signature
  119. * immediately if we can.
  120. */
  121. int x509_check_for_self_signed(struct x509_certificate *cert)
  122. {
  123. int ret = 0;
  124. pr_devel("==>%s()\n", __func__);
  125. if (cert->raw_subject_size != cert->raw_issuer_size ||
  126. memcmp(cert->raw_subject, cert->raw_issuer,
  127. cert->raw_issuer_size) != 0)
  128. goto not_self_signed;
  129. if (cert->sig->auth_ids[0] || cert->sig->auth_ids[1]) {
  130. /* If the AKID is present it may have one or two parts. If
  131. * both are supplied, both must match.
  132. */
  133. bool a = asymmetric_key_id_same(cert->skid, cert->sig->auth_ids[1]);
  134. bool b = asymmetric_key_id_same(cert->id, cert->sig->auth_ids[0]);
  135. if (!a && !b)
  136. goto not_self_signed;
  137. ret = -EKEYREJECTED;
  138. if (((a && !b) || (b && !a)) &&
  139. cert->sig->auth_ids[0] && cert->sig->auth_ids[1])
  140. goto out;
  141. }
  142. ret = -EKEYREJECTED;
  143. if (strcmp(cert->pub->pkey_algo, cert->sig->pkey_algo) != 0)
  144. goto out;
  145. ret = public_key_verify_signature(cert->pub, cert->sig);
  146. if (ret < 0) {
  147. if (ret == -ENOPKG) {
  148. cert->unsupported_sig = true;
  149. ret = 0;
  150. }
  151. goto out;
  152. }
  153. pr_devel("Cert Self-signature verified");
  154. cert->self_signed = true;
  155. out:
  156. pr_devel("<==%s() = %d\n", __func__, ret);
  157. return ret;
  158. not_self_signed:
  159. pr_devel("<==%s() = 0 [not]\n", __func__);
  160. return 0;
  161. }
  162. #ifndef __UBOOT__
  163. /*
  164. * Attempt to parse a data blob for a key as an X509 certificate.
  165. */
  166. static int x509_key_preparse(struct key_preparsed_payload *prep)
  167. {
  168. struct asymmetric_key_ids *kids;
  169. struct x509_certificate *cert;
  170. const char *q;
  171. size_t srlen, sulen;
  172. char *desc = NULL, *p;
  173. int ret;
  174. cert = x509_cert_parse(prep->data, prep->datalen);
  175. if (IS_ERR(cert))
  176. return PTR_ERR(cert);
  177. pr_devel("Cert Issuer: %s\n", cert->issuer);
  178. pr_devel("Cert Subject: %s\n", cert->subject);
  179. if (cert->unsupported_key) {
  180. ret = -ENOPKG;
  181. goto error_free_cert;
  182. }
  183. pr_devel("Cert Key Algo: %s\n", cert->pub->pkey_algo);
  184. pr_devel("Cert Valid period: %lld-%lld\n", cert->valid_from, cert->valid_to);
  185. cert->pub->id_type = "X509";
  186. if (cert->unsupported_sig) {
  187. public_key_signature_free(cert->sig);
  188. cert->sig = NULL;
  189. } else {
  190. pr_devel("Cert Signature: %s + %s\n",
  191. cert->sig->pkey_algo, cert->sig->hash_algo);
  192. }
  193. /* Don't permit addition of blacklisted keys */
  194. ret = -EKEYREJECTED;
  195. if (cert->blacklisted)
  196. goto error_free_cert;
  197. /* Propose a description */
  198. sulen = strlen(cert->subject);
  199. if (cert->raw_skid) {
  200. srlen = cert->raw_skid_size;
  201. q = cert->raw_skid;
  202. } else {
  203. srlen = cert->raw_serial_size;
  204. q = cert->raw_serial;
  205. }
  206. ret = -ENOMEM;
  207. desc = kmalloc(sulen + 2 + srlen * 2 + 1, GFP_KERNEL);
  208. if (!desc)
  209. goto error_free_cert;
  210. p = memcpy(desc, cert->subject, sulen);
  211. p += sulen;
  212. *p++ = ':';
  213. *p++ = ' ';
  214. p = bin2hex(p, q, srlen);
  215. *p = 0;
  216. kids = kmalloc(sizeof(struct asymmetric_key_ids), GFP_KERNEL);
  217. if (!kids)
  218. goto error_free_desc;
  219. kids->id[0] = cert->id;
  220. kids->id[1] = cert->skid;
  221. /* We're pinning the module by being linked against it */
  222. __module_get(public_key_subtype.owner);
  223. prep->payload.data[asym_subtype] = &public_key_subtype;
  224. prep->payload.data[asym_key_ids] = kids;
  225. prep->payload.data[asym_crypto] = cert->pub;
  226. prep->payload.data[asym_auth] = cert->sig;
  227. prep->description = desc;
  228. prep->quotalen = 100;
  229. /* We've finished with the certificate */
  230. cert->pub = NULL;
  231. cert->id = NULL;
  232. cert->skid = NULL;
  233. cert->sig = NULL;
  234. desc = NULL;
  235. ret = 0;
  236. error_free_desc:
  237. kfree(desc);
  238. error_free_cert:
  239. x509_free_certificate(cert);
  240. return ret;
  241. }
  242. static struct asymmetric_key_parser x509_key_parser = {
  243. .owner = THIS_MODULE,
  244. .name = "x509",
  245. .parse = x509_key_preparse,
  246. };
  247. /*
  248. * Module stuff
  249. */
  250. static int __init x509_key_init(void)
  251. {
  252. return register_asymmetric_key_parser(&x509_key_parser);
  253. }
  254. static void __exit x509_key_exit(void)
  255. {
  256. unregister_asymmetric_key_parser(&x509_key_parser);
  257. }
  258. module_init(x509_key_init);
  259. module_exit(x509_key_exit);
  260. #endif /* !__UBOOT__ */
  261. MODULE_DESCRIPTION("X.509 certificate parser");
  262. MODULE_AUTHOR("Red Hat, Inc.");
  263. MODULE_LICENSE("GPL");