1 files changed, 275 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 000000000..9338b4558
--- /dev/null
+++ b/crypto/asymmetric_keys/x509_public_key.c
@@ -0,0 +1,275 @@
+/* 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 <keys/asymmetric-subtype.h>
+#include <keys/asymmetric-parser.h>
+#include <keys/system_keyring.h>
+#include <crypto/hash.h>
+#include "asymmetric_keys.h"
+#include "x509_parser.h"
+
+/*
+ * Set up the signature parameters in an X.509 certificate.  This involves
+ * digesting the signed data and extracting the signature.
+ */
+int x509_get_sig_params(struct x509_certificate *cert)
+{
+	struct public_key_signature *sig = cert->sig;
+	struct crypto_shash *tfm;
+	struct shash_desc *desc;
+	size_t desc_size;
+	int ret;
+
+	pr_devel("==>%s()\n", __func__);
+
+	if (!cert->pub->pkey_algo)
+		cert->unsupported_key = true;
+
+	if (!sig->pkey_algo)
+		cert->unsupported_sig = true;
+
+	/* We check the hash if we can - even if we can't then verify it */
+	if (!sig->hash_algo) {
+		cert->unsupported_sig = true;
+		return 0;
+	}
+
+	sig->s = kmemdup(cert->raw_sig, cert->raw_sig_size, GFP_KERNEL);
+	if (!sig->s)
+		return -ENOMEM;
+
+	sig->s_size = cert->raw_sig_size;
+
+	/* Allocate the hashing algorithm we're going to need and find out how
+	 * big the hash operational data will be.
+	 */
+	tfm = crypto_alloc_shash(sig->hash_algo, 0, 0);
+	if (IS_ERR(tfm)) {
+		if (PTR_ERR(tfm) == -ENOENT) {
+			cert->unsupported_sig = true;
+			return 0;
+		}
+		return PTR_ERR(tfm);
+	}
+
+	desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
+	sig->digest_size = crypto_shash_digestsize(tfm);
+
+	ret = -ENOMEM;
+	sig->digest = kmalloc(sig->digest_size, GFP_KERNEL);
+	if (!sig->digest)
+		goto error;
+
+	desc = kzalloc(desc_size, GFP_KERNEL);
+	if (!desc)
+		goto error;
+
+	desc->tfm = tfm;
+	desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
+
+	ret = crypto_shash_digest(desc, cert->tbs, cert->tbs_size, sig->digest);
+	if (ret < 0)
+		goto error_2;
+
+	ret = is_hash_blacklisted(sig->digest, sig->digest_size, "tbs");
+	if (ret == -EKEYREJECTED) {
+		pr_err("Cert %*phN is blacklisted\n",
+		       sig->digest_size, sig->digest);
+		cert->blacklisted = true;
+		ret = 0;
+	}
+
+error_2:
+	kfree(desc);
+error:
+	crypto_free_shash(tfm);
+	pr_devel("<==%s() = %d\n", __func__, ret);
+	return ret;
+}
+
+/*
+ * Check for self-signedness in an X.509 cert and if found, check the signature
+ * immediately if we can.
+ */
+int x509_check_for_self_signed(struct x509_certificate *cert)
+{
+	int ret = 0;
+
+	pr_devel("==>%s()\n", __func__);
+
+	if (cert->raw_subject_size != cert->raw_issuer_size ||
+	    memcmp(cert->raw_subject, cert->raw_issuer,
+		   cert->raw_issuer_size) != 0)
+		goto not_self_signed;
+
+	if (cert->sig->auth_ids[0] || cert->sig->auth_ids[1]) {
+		/* If the AKID is present it may have one or two parts.  If
+		 * both are supplied, both must match.
+		 */
+		bool a = asymmetric_key_id_same(cert->skid, cert->sig->auth_ids[1]);
+		bool b = asymmetric_key_id_same(cert->id, cert->sig->auth_ids[0]);
+
+		if (!a && !b)
+			goto not_self_signed;
+
+		ret = -EKEYREJECTED;
+		if (((a && !b) || (b && !a)) &&
+		    cert->sig->auth_ids[0] && cert->sig->auth_ids[1])
+			goto out;
+	}
+
+	ret = -EKEYREJECTED;
+	if (strcmp(cert->pub->pkey_algo, cert->sig->pkey_algo) != 0)
+		goto out;
+
+	ret = public_key_verify_signature(cert->pub, cert->sig);
+	if (ret < 0) {
+		if (ret == -ENOPKG) {
+			cert->unsupported_sig = true;
+			ret = 0;
+		}
+		goto out;
+	}
+
+	pr_devel("Cert Self-signature verified");
+	cert->self_signed = true;
+
+out:
+	pr_devel("<==%s() = %d\n", __func__, ret);
+	return ret;
+
+not_self_signed:
+	pr_devel("<==%s() = 0 [not]\n", __func__);
+	return 0;
+}
+
+/*
+ * Attempt to parse a data blob for a key as an X509 certificate.
+ */
+static int x509_key_preparse(struct key_preparsed_payload *prep)
+{
+	struct asymmetric_key_ids *kids;
+	struct x509_certificate *cert;
+	const char *q;
+	size_t srlen, sulen;
+	char *desc = NULL, *p;
+	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);
+
+	if (cert->unsupported_key) {
+		ret = -ENOPKG;
+		goto error_free_cert;
+	}
+
+	pr_devel("Cert Key Algo: %s\n", cert->pub->pkey_algo);
+	pr_devel("Cert Valid period: %lld-%lld\n", cert->valid_from, cert->valid_to);
+
+	cert->pub->id_type = "X509";
+
+	if (cert->unsupported_sig) {
+		public_key_signature_free(cert->sig);
+		cert->sig = NULL;
+	} else {
+		pr_devel("Cert Signature: %s + %s\n",
+			 cert->sig->pkey_algo, cert->sig->hash_algo);
+	}
+
+	/* Don't permit addition of blacklisted keys */
+	ret = -EKEYREJECTED;
+	if (cert->blacklisted)
+		goto error_free_cert;
+
+	/* Propose a description */
+	sulen = strlen(cert->subject);
+	if (cert->raw_skid) {
+		srlen = cert->raw_skid_size;
+		q = cert->raw_skid;
+	} else {
+		srlen = cert->raw_serial_size;
+		q = cert->raw_serial;
+	}
+
+	ret = -ENOMEM;
+	desc = kmalloc(sulen + 2 + srlen * 2 + 1, GFP_KERNEL);
+	if (!desc)
+		goto error_free_cert;
+	p = memcpy(desc, cert->subject, sulen);
+	p += sulen;
+	*p++ = ':';
+	*p++ = ' ';
+	p = bin2hex(p, q, srlen);
+	*p = 0;
+
+	kids = kmalloc(sizeof(struct asymmetric_key_ids), GFP_KERNEL);
+	if (!kids)
+		goto error_free_desc;
+	kids->id[0] = cert->id;
+	kids->id[1] = cert->skid;
+
+	/* We're pinning the module by being linked against it */
+	__module_get(public_key_subtype.owner);
+	prep->payload.data[asym_subtype] = &public_key_subtype;
+	prep->payload.data[asym_key_ids] = kids;
+	prep->payload.data[asym_crypto] = cert->pub;
+	prep->payload.data[asym_auth] = cert->sig;
+	prep->description = desc;
+	prep->quotalen = 100;
+
+	/* We've finished with the certificate */
+	cert->pub = NULL;
+	cert->id = NULL;
+	cert->skid = NULL;
+	cert->sig = NULL;
+	desc = NULL;
+	ret = 0;
+
+error_free_desc:
+	kfree(desc);
+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);
+
+MODULE_DESCRIPTION("X.509 certificate parser");
+MODULE_AUTHOR("Red Hat, Inc.");
+MODULE_LICENSE("GPL");