diff options
Diffstat (limited to 'crypto/asymmetric_keys/x509_public_key.c')
| -rw-r--r-- | crypto/asymmetric_keys/x509_public_key.c | 207 |
1 files changed, 207 insertions, 0 deletions
diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c new file mode 100644 index 000000000000..716917ce0907 --- /dev/null +++ b/crypto/asymmetric_keys/x509_public_key.c @@ -0,0 +1,207 @@ +/* Instantiate a public key crypto key from an X.509 Certificate + * + * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public Licence + * as published by the Free Software Foundation; either version + * 2 of the Licence, or (at your option) any later version. + */ + +#define pr_fmt(fmt) "X.509: "fmt +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/slab.h> +#include <linux/err.h> +#include <linux/mpi.h> +#include <linux/asn1_decoder.h> +#include <keys/asymmetric-subtype.h> +#include <keys/asymmetric-parser.h> +#include <crypto/hash.h> +#include "asymmetric_keys.h" +#include "public_key.h" +#include "x509_parser.h" + +static const +struct public_key_algorithm *x509_public_key_algorithms[PKEY_ALGO__LAST] = { + [PKEY_ALGO_DSA] = NULL, +#if defined(CONFIG_PUBLIC_KEY_ALGO_RSA) || \ + defined(CONFIG_PUBLIC_KEY_ALGO_RSA_MODULE) + [PKEY_ALGO_RSA] = &RSA_public_key_algorithm, +#endif +}; + +/* + * Check the signature on a certificate using the provided public key + */ +static int x509_check_signature(const struct public_key *pub, + const struct x509_certificate *cert) +{ + struct public_key_signature *sig; + struct crypto_shash *tfm; + struct shash_desc *desc; + size_t digest_size, desc_size; + int ret; + + pr_devel("==>%s()\n", __func__); + + /* Allocate the hashing algorithm we're going to need and find out how + * big the hash operational data will be. + */ + tfm = crypto_alloc_shash(pkey_hash_algo[cert->sig_hash_algo], 0, 0); + if (IS_ERR(tfm)) + return (PTR_ERR(tfm) == -ENOENT) ? -ENOPKG : PTR_ERR(tfm); + + desc_size = crypto_shash_descsize(tfm) + sizeof(*desc); + digest_size = crypto_shash_digestsize(tfm); + + /* We allocate the hash operational data storage on the end of our + * context data. + */ + ret = -ENOMEM; + sig = kzalloc(sizeof(*sig) + desc_size + digest_size, GFP_KERNEL); + if (!sig) + goto error_no_sig; + + sig->pkey_hash_algo = cert->sig_hash_algo; + sig->digest = (u8 *)sig + sizeof(*sig) + desc_size; + sig->digest_size = digest_size; + + desc = (void *)sig + sizeof(*sig); + desc->tfm = tfm; + desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP; + + ret = crypto_shash_init(desc); + if (ret < 0) + goto error; + + ret = -ENOMEM; + sig->rsa.s = mpi_read_raw_data(cert->sig, cert->sig_size); + if (!sig->rsa.s) + goto error; + + ret = crypto_shash_finup(desc, cert->tbs, cert->tbs_size, sig->digest); + if (ret < 0) + goto error_mpi; + + ret = pub->algo->verify_signature(pub, sig); + + pr_debug("Cert Verification: %d\n", ret); + +error_mpi: + mpi_free(sig->rsa.s); +error: + kfree(sig); +error_no_sig: + crypto_free_shash(tfm); + + pr_devel("<==%s() = %d\n", __func__, ret); + return ret; +} + +/* + * Attempt to parse a data blob for a key as an X509 certificate. + */ +static int x509_key_preparse(struct key_preparsed_payload *prep) +{ + struct x509_certificate *cert; + time_t now; + size_t srlen, sulen; + char *desc = NULL; + int ret; + + cert = x509_cert_parse(prep->data, prep->datalen); + if (IS_ERR(cert)) + return PTR_ERR(cert); + + pr_devel("Cert Issuer: %s\n", cert->issuer); + pr_devel("Cert Subject: %s\n", cert->subject); + pr_devel("Cert Key Algo: %s\n", pkey_algo[cert->pkey_algo]); + pr_devel("Cert Valid: %lu - %lu\n", cert->valid_from, cert->valid_to); + pr_devel("Cert Signature: %s + %s\n", + pkey_algo[cert->sig_pkey_algo], + pkey_hash_algo[cert->sig_hash_algo]); + + if (!cert->fingerprint || !cert->authority) { + pr_warn("Cert for '%s' must have SubjKeyId and AuthKeyId extensions\n", + cert->subject); + ret = -EKEYREJECTED; + goto error_free_cert; + } + + now = CURRENT_TIME.tv_sec; + if (now < cert->valid_from) { + pr_warn("Cert %s is not yet valid\n", cert->fingerprint); + ret = -EKEYREJECTED; + goto error_free_cert; + } + if (now >= cert->valid_to) { + pr_warn("Cert %s has expired\n", cert->fingerprint); + ret = -EKEYEXPIRED; + goto error_free_cert; + } + + cert->pub->algo = x509_public_key_algorithms[cert->pkey_algo]; + cert->pub->id_type = PKEY_ID_X509; + + /* Check the signature on the key */ + if (strcmp(cert->fingerprint, cert->authority) == 0) { + ret = x509_check_signature(cert->pub, cert); + if (ret < 0) + goto error_free_cert; + } + + /* Propose a description */ + sulen = strlen(cert->subject); + srlen = strlen(cert->fingerprint); + ret = -ENOMEM; + desc = kmalloc(sulen + 2 + srlen + 1, GFP_KERNEL); + if (!desc) + goto error_free_cert; + memcpy(desc, cert->subject, sulen); + desc[sulen] = ':'; + desc[sulen + 1] = ' '; + memcpy(desc + sulen + 2, cert->fingerprint, srlen); + desc[sulen + 2 + srlen] = 0; + + /* We're pinning the module by being linked against it */ + __module_get(public_key_subtype.owner); + prep->type_data[0] = &public_key_subtype; + prep->type_data[1] = cert->fingerprint; + prep->payload = cert->pub; + prep->description = desc; + prep->quotalen = 100; + + /* We've finished with the certificate */ + cert->pub = NULL; + cert->fingerprint = NULL; + desc = NULL; + ret = 0; + +error_free_cert: + x509_free_certificate(cert); + return ret; +} + +static struct asymmetric_key_parser x509_key_parser = { + .owner = THIS_MODULE, + .name = "x509", + .parse = x509_key_preparse, +}; + +/* + * Module stuff + */ +static int __init x509_key_init(void) +{ + return register_asymmetric_key_parser(&x509_key_parser); +} + +static void __exit x509_key_exit(void) +{ + unregister_asymmetric_key_parser(&x509_key_parser); +} + +module_init(x509_key_init); +module_exit(x509_key_exit); |