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Diffstat (limited to 'crypto/asymmetric_keys/x509_public_key.c')
-rw-r--r--crypto/asymmetric_keys/x509_public_key.c207
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);