crypto/asymmetric_keys/x509_public_key.c - kernel/common - Git at Google

 /* Instantiate a public key crypto key from an X.509 Certificate
  *
  * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells ([email protected])
  *
  * 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");
	/* Instantiate a public key crypto key from an X.509 Certificate
	*
	* Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
	* Written by David Howells ([email protected])
	*
	* 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");