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Commit b426beb6 authored by David Howells's avatar David Howells
Browse files

X.509: Embed public_key_signature struct and create filler function 



Embed a public_key_signature struct in struct x509_certificate, eliminating
now unnecessary fields, and split x509_check_signature() to create a filler
function for it that attaches a digest of the signed data and an MPI that
represents the signature data.  x509_free_certificate() is then modified to
deal with these.

Whilst we're at it, export both x509_check_signature() and the new
x509_get_sig_params().

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Reviewed-by: default avatarJosh Boyer <jwboyer@redhat.com>
parent 57be4a78

crypto/asymmetric_keys/x509_cert_parser.c

+16 −14
Original line number Diff line number Diff line
@@ -47,6 +47,8 @@ void x509_free_certificate(struct x509_certificate *cert) 
		kfree(cert->subject);

		kfree(cert->fingerprint);

		kfree(cert->authority);

		kfree(cert->sig.digest);

		mpi_free(cert->sig.rsa.s);

		kfree(cert);

	}

}
@@ -152,33 +154,33 @@ int x509_note_pkey_algo(void *context, size_t hdrlen, 
		return -ENOPKG; /* Unsupported combination */



	case OID_md4WithRSAEncryption:

		ctx->cert->sig_hash_algo = PKEY_HASH_MD5;

		ctx->cert->sig_pkey_algo = PKEY_ALGO_RSA;

		ctx->cert->sig.pkey_hash_algo = PKEY_HASH_MD5;

		ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;

		break;



	case OID_sha1WithRSAEncryption:

		ctx->cert->sig_hash_algo = PKEY_HASH_SHA1;

		ctx->cert->sig_pkey_algo = PKEY_ALGO_RSA;

		ctx->cert->sig.pkey_hash_algo = PKEY_HASH_SHA1;

		ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;

		break;



	case OID_sha256WithRSAEncryption:

		ctx->cert->sig_hash_algo = PKEY_HASH_SHA256;

		ctx->cert->sig_pkey_algo = PKEY_ALGO_RSA;

		ctx->cert->sig.pkey_hash_algo = PKEY_HASH_SHA256;

		ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;

		break;



	case OID_sha384WithRSAEncryption:

		ctx->cert->sig_hash_algo = PKEY_HASH_SHA384;

		ctx->cert->sig_pkey_algo = PKEY_ALGO_RSA;

		ctx->cert->sig.pkey_hash_algo = PKEY_HASH_SHA384;

		ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;

		break;



	case OID_sha512WithRSAEncryption:

		ctx->cert->sig_hash_algo = PKEY_HASH_SHA512;

		ctx->cert->sig_pkey_algo = PKEY_ALGO_RSA;

		ctx->cert->sig.pkey_hash_algo = PKEY_HASH_SHA512;

		ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;

		break;



	case OID_sha224WithRSAEncryption:

		ctx->cert->sig_hash_algo = PKEY_HASH_SHA224;

		ctx->cert->sig_pkey_algo = PKEY_ALGO_RSA;

		ctx->cert->sig.pkey_hash_algo = PKEY_HASH_SHA224;

		ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;

		break;

	}
@@ -203,8 +205,8 @@ int x509_note_signature(void *context, size_t hdrlen, 
		return -EINVAL;

	}



	ctx->cert->sig = value;

	ctx->cert->sig_size = vlen;

	ctx->cert->raw_sig = value;

	ctx->cert->raw_sig_size = vlen;

	return 0;

}

crypto/asymmetric_keys/x509_parser.h

+11 −5
Original line number Diff line number Diff line
@@ -21,12 +21,11 @@ struct x509_certificate { 
	char		*authority;		/* Authority key fingerprint as hex */

	struct tm	valid_from;

	struct tm	valid_to;

	enum pkey_algo	sig_pkey_algo : 8;	/* Signature public key algorithm */

	enum pkey_hash_algo sig_hash_algo : 8;	/* Signature hash algorithm */

	const void	*tbs;			/* Signed data */

	size_t		tbs_size;		/* Size of signed data */

	const void	*sig;			/* Signature data */

	size_t		sig_size;		/* Size of sigature */

	unsigned	tbs_size;		/* Size of signed data */

	unsigned	raw_sig_size;		/* Size of sigature */

	const void	*raw_sig;		/* Signature data */

	struct public_key_signature sig;	/* Signature parameters */

};



/*
@@ -34,3 +33,10 @@ struct x509_certificate { 
 */

extern void x509_free_certificate(struct x509_certificate *cert);

extern struct x509_certificate *x509_cert_parse(const void *data, size_t datalen);



/*

 * x509_public_key.c

 */

extern int x509_get_sig_params(struct x509_certificate *cert);

extern int x509_check_signature(const struct public_key *pub,

				struct x509_certificate *cert);

crypto/asymmetric_keys/x509_public_key.c

+47 −36
Original line number Diff line number Diff line
@@ -24,72 +24,83 @@ 
#include "x509_parser.h"



/*

 * Check the signature on a certificate using the provided public key

 * Set up the signature parameters in an X.509 certificate.  This involves

 * digesting the signed data and extracting the signature.

 */

static int x509_check_signature(const struct public_key *pub,

				const struct x509_certificate *cert)

int x509_get_sig_params(struct x509_certificate *cert)

{

	struct public_key_signature *sig;

	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->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(pkey_hash_algo_name[cert->sig_hash_algo], 0, 0);

	tfm = crypto_alloc_shash(pkey_hash_algo_name[cert->sig.pkey_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.

	/* We allocate the hash operational data storage on the end of the

	 * digest storage space.

	 */

	ret = -ENOMEM;

	sig = kzalloc(sizeof(*sig) + desc_size + digest_size, GFP_KERNEL);

	if (!sig)

		goto error_no_sig;

	digest = kzalloc(digest_size + desc_size, GFP_KERNEL);

	if (!digest)

		goto error;



	sig->pkey_hash_algo	= cert->sig_hash_algo;

	sig->digest		= (u8 *)sig + sizeof(*sig) + desc_size;

	sig->digest_size	= digest_size;

	cert->sig.digest = digest;

	cert->sig.digest_size = digest_size;



	desc = (void *)sig + sizeof(*sig);

	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);



	ret = -ENOMEM;

	sig->rsa.s = mpi_read_raw_data(cert->sig, cert->sig_size);

	if (!sig->rsa.s)

		goto error;

/*

 * 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;



	ret = crypto_shash_finup(desc, cert->tbs, cert->tbs_size, sig->digest);

	if (ret < 0)

		goto error_mpi;

	pr_devel("==>%s()\n", __func__);



	ret = public_key_verify_signature(pub, sig);

	ret = x509_get_sig_params(cert);

	if (ret < 0)

		return ret;



	ret = public_key_verify_signature(pub, &cert->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;

}

EXPORT_SYMBOL_GPL(x509_check_signature);



/*

 * Attempt to parse a data blob for a key as an X509 certificate.
@@ -118,8 +129,8 @@ static int x509_key_preparse(struct key_preparsed_payload *prep) 
		 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],

		 pkey_hash_algo_name[cert->sig_hash_algo]);

		 pkey_algo_name[cert->sig.pkey_algo],

		 pkey_hash_algo_name[cert->sig.pkey_hash_algo]);



	if (!cert->fingerprint || !cert->authority) {

		pr_warn("Cert for '%s' must have SubjKeyId and AuthKeyId extensions\n",