1 files changed, 377 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..24f17e6c5
--- /dev/null
+++ b/crypto/asymmetric_keys/x509_public_key.c
@@ -0,0 +1,377 @@
+/* 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 <keys/system_keyring.h>
+#include <crypto/hash.h>
+#include "asymmetric_keys.h"
+#include "public_key.h"
+#include "x509_parser.h"
+
+static bool use_builtin_keys;
+static struct asymmetric_key_id *ca_keyid;
+
+#ifndef MODULE
+static struct {
+	struct asymmetric_key_id id;
+	unsigned char data[10];
+} cakey;
+
+static int __init ca_keys_setup(char *str)
+{
+	if (!str)		/* default system keyring */
+		return 1;
+
+	if (strncmp(str, "id:", 3) == 0) {
+		struct asymmetric_key_id *p = &cakey.id;
+		size_t hexlen = (strlen(str) - 3) / 2;
+		int ret;
+
+		if (hexlen == 0 || hexlen > sizeof(cakey.data)) {
+			pr_err("Missing or invalid ca_keys id\n");
+			return 1;
+		}
+
+		ret = __asymmetric_key_hex_to_key_id(str + 3, p, hexlen);
+		if (ret < 0)
+			pr_err("Unparsable ca_keys id hex string\n");
+		else
+			ca_keyid = p;	/* owner key 'id:xxxxxx' */
+	} else if (strcmp(str, "builtin") == 0) {
+		use_builtin_keys = true;
+	}
+
+	return 1;
+}
+__setup("ca_keys=", ca_keys_setup);
+#endif
+
+/**
+ * x509_request_asymmetric_key - Request a key by X.509 certificate params.
+ * @keyring: The keys to search.
+ * @kid: The key ID.
+ * @partial: Use partial match if true, exact if false.
+ *
+ * Find a key in the given keyring by subject name and key ID.  These might,
+ * for instance, be the issuer name and the authority key ID of an X.509
+ * certificate that needs to be verified.
+ */
+struct key *x509_request_asymmetric_key(struct key *keyring,
+					const struct asymmetric_key_id *kid,
+					bool partial)
+{
+	key_ref_t key;
+	char *id, *p;
+
+	/* Construct an identifier "id:<keyid>". */
+	p = id = kmalloc(2 + 1 + kid->len * 2 + 1, GFP_KERNEL);
+	if (!id)
+		return ERR_PTR(-ENOMEM);
+
+	if (partial) {
+		*p++ = 'i';
+		*p++ = 'd';
+	} else {
+		*p++ = 'e';
+		*p++ = 'x';
+	}
+	*p++ = ':';
+	p = bin2hex(p, kid->data, kid->len);
+	*p = 0;
+
+	pr_debug("Look up: \"%s\"\n", id);
+
+	key = keyring_search(make_key_ref(keyring, 1),
+			     &key_type_asymmetric, id);
+	if (IS_ERR(key))
+		pr_debug("Request for key '%s' err %ld\n", id, PTR_ERR(key));
+	kfree(id);
+
+	if (IS_ERR(key)) {
+		switch (PTR_ERR(key)) {
+			/* Hide some search errors */
+		case -EACCES:
+		case -ENOTDIR:
+		case -EAGAIN:
+			return ERR_PTR(-ENOKEY);
+		default:
+			return ERR_CAST(key);
+		}
+	}
+
+	pr_devel("<==%s() = 0 [%x]\n", __func__,
+		 key_serial(key_ref_to_ptr(key)));
+	return key_ref_to_ptr(key);
+}
+EXPORT_SYMBOL_GPL(x509_request_asymmetric_key);
+
+/*
+ * 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 crypto_shash *tfm;
+	struct shash_desc *desc;
+	size_t digest_size, desc_size;
+	void *digest;
+	int ret;
+
+	pr_devel("==>%s()\n", __func__);
+
+	if (cert->unsupported_crypto)
+		return -ENOPKG;
+	if (cert->sig.rsa.s)
+		return 0;
+
+	cert->sig.rsa.s = mpi_read_raw_data(cert->raw_sig, cert->raw_sig_size);
+	if (!cert->sig.rsa.s)
+		return -ENOMEM;
+	cert->sig.nr_mpi = 1;
+
+	/* Allocate the hashing algorithm we're going to need and find out how
+	 * big the hash operational data will be.
+	 */
+	tfm = crypto_alloc_shash(hash_algo_name[cert->sig.pkey_hash_algo], 0, 0);
+	if (IS_ERR(tfm)) {
+		if (PTR_ERR(tfm) == -ENOENT) {
+			cert->unsupported_crypto = true;
+			return -ENOPKG;
+		}
+		return 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 the
+	 * digest storage space.
+	 */
+	ret = -ENOMEM;
+	digest = kzalloc(digest_size + desc_size, GFP_KERNEL);
+	if (!digest)
+		goto error;
+
+	cert->sig.digest = digest;
+	cert->sig.digest_size = digest_size;
+
+	desc = digest + digest_size;
+	desc->tfm = tfm;
+	desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
+
+	ret = crypto_shash_init(desc);
+	if (ret < 0)
+		goto error;
+	might_sleep();
+	ret = crypto_shash_finup(desc, cert->tbs, cert->tbs_size, digest);
+error:
+	crypto_free_shash(tfm);
+	pr_devel("<==%s() = %d\n", __func__, ret);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(x509_get_sig_params);
+
+/*
+ * Check the signature on a certificate using the provided public key
+ */
+int x509_check_signature(const struct public_key *pub,
+			 struct x509_certificate *cert)
+{
+	int ret;
+
+	pr_devel("==>%s()\n", __func__);
+
+	ret = x509_get_sig_params(cert);
+	if (ret < 0)
+		return ret;
+
+	ret = public_key_verify_signature(pub, &cert->sig);
+	if (ret == -ENOPKG)
+		cert->unsupported_crypto = true;
+	pr_debug("Cert Verification: %d\n", ret);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(x509_check_signature);
+
+/*
+ * Check the new certificate against the ones in the trust keyring.  If one of
+ * those is the signing key and validates the new certificate, then mark the
+ * new certificate as being trusted.
+ *
+ * Return 0 if the new certificate was successfully validated, 1 if we couldn't
+ * find a matching parent certificate in the trusted list and an error if there
+ * is a matching certificate but the signature check fails.
+ */
+static int x509_validate_trust(struct x509_certificate *cert,
+			       struct key *trust_keyring)
+{
+	struct key *key;
+	int ret = 1;
+
+	if (!trust_keyring)
+		return -EOPNOTSUPP;
+
+	if (ca_keyid && !asymmetric_key_id_partial(cert->authority, ca_keyid))
+		return -EPERM;
+
+	key = x509_request_asymmetric_key(trust_keyring, cert->authority,
+					  false);
+	if (!IS_ERR(key))  {
+		if (!use_builtin_keys
+		    || test_bit(KEY_FLAG_BUILTIN, &key->flags))
+			ret = x509_check_signature(key->payload.data, cert);
+		key_put(key);
+	}
+	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 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->pub->pkey_algo >= PKEY_ALGO__LAST ||
+	    cert->sig.pkey_algo >= PKEY_ALGO__LAST ||
+	    cert->sig.pkey_hash_algo >= PKEY_HASH__LAST ||
+	    !pkey_algo[cert->pub->pkey_algo] ||
+	    !pkey_algo[cert->sig.pkey_algo] ||
+	    !hash_algo_name[cert->sig.pkey_hash_algo]) {
+		ret = -ENOPKG;
+		goto error_free_cert;
+	}
+
+	pr_devel("Cert Key Algo: %s\n", pkey_algo_name[cert->pub->pkey_algo]);
+	pr_devel("Cert Valid From: %04ld-%02d-%02d %02d:%02d:%02d\n",
+		 cert->valid_from.tm_year + 1900, cert->valid_from.tm_mon + 1,
+		 cert->valid_from.tm_mday, cert->valid_from.tm_hour,
+		 cert->valid_from.tm_min,  cert->valid_from.tm_sec);
+	pr_devel("Cert Valid To: %04ld-%02d-%02d %02d:%02d:%02d\n",
+		 cert->valid_to.tm_year + 1900, cert->valid_to.tm_mon + 1,
+		 cert->valid_to.tm_mday, cert->valid_to.tm_hour,
+		 cert->valid_to.tm_min,  cert->valid_to.tm_sec);
+	pr_devel("Cert Signature: %s + %s\n",
+		 pkey_algo_name[cert->sig.pkey_algo],
+		 hash_algo_name[cert->sig.pkey_hash_algo]);
+
+	cert->pub->algo = pkey_algo[cert->pub->pkey_algo];
+	cert->pub->id_type = PKEY_ID_X509;
+
+	/* Check the signature on the key if it appears to be self-signed */
+	if (!cert->authority ||
+	    asymmetric_key_id_same(cert->skid, cert->authority)) {
+		ret = x509_check_signature(cert->pub, cert); /* self-signed */
+		if (ret < 0)
+			goto error_free_cert;
+	} else if (!prep->trusted) {
+		ret = x509_validate_trust(cert, get_system_trusted_keyring());
+		if (!ret)
+			prep->trusted = 1;
+	}
+
+	/* 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;
+	}
+	if (srlen > 1 && *q == 0) {
+		srlen--;
+		q++;
+	}
+
+	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->type_data[0] = &public_key_subtype;
+	prep->type_data[1] = kids;
+	prep->payload[0] = cert->pub;
+	prep->description = desc;
+	prep->quotalen = 100;
+
+	/* We've finished with the certificate */
+	cert->pub = NULL;
+	cert->id = NULL;
+	cert->skid = 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_LICENSE("GPL");