Message-ID: <20181210193739.g7ald2ufik56fccf@sole.flsd.net>
Date:   Mon, 10 Dec 2018 22:37:39 +0300
From:   Vitaly Chikunov <vt@...linux.org>
To:     David Howells <dhowells@...hat.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>, keyrings@...r.kernel.org,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH] X.509: Parse public key parameters from x509 for
 akcipher

On Sun, Dec 09, 2018 at 04:55:48PM +0300, Vitaly Chikunov wrote:
> Some public key algorithms (like ECDSA) keep in parameters field
> important data such as digest and curve OIDs (possibly more for
> different ECDSA variants). Thus, just setting a public key (as
> for RSA) is not enough.
> 
> Introduce set_params() callback for akcipher which will be used to
> pass BER encoded parameters array, with additional argument of
> algorithm OID.
> 
> This is done with the intent of adding support for EC-RDSA (ISO/IEC
> 14888-3:2018, RFC 7091, and basically ECDSA variant) public keys (which
> will be finally used in IMA subsystem). Thus, also oid_registry.h is
> updated.
> 
> Rationale:
> 
> - For such keys just setting public key without parameters is
>   meaningless, so it would be possible to add parameters in
>   crypto_akcipher_set_pub_key (and .set_pub_key) calls. But, this will
>   needlessly change API for RSA akcipher. Also, additional callback
>   making it possible to pass parameters after
>   crypto_akcipher_set_priv_key (and .set_priv_key) in the future.
> 
> - Algorithm OID is passed to be validated in .set_params callback,
>   otherwise, it could have the wrong value.
> 
> - Particular algorithm OIDs are checked in x509_note_params, (because
>   this is called from AlgorithmIdentifier (ASN.1) parser, which is
>   called multiple times, as it's used multiple times in X.509
>   certificate), to distinguish a public key call from a signature call.
> 
> Signed-off-by: Vitaly Chikunov <vt@...linux.org>
> ---
>  crypto/asymmetric_keys/public_key.c       | 16 +++++++++++++++
>  crypto/asymmetric_keys/x509.asn1          |  2 +-
>  crypto/asymmetric_keys/x509_cert_parser.c | 27 +++++++++++++++++++++++++
>  crypto/testmgr.c                          |  5 +++++
>  crypto/testmgr.h                          |  3 +++
>  include/crypto/akcipher.h                 | 33 +++++++++++++++++++++++++++++++
>  include/crypto/public_key.h               |  4 ++++
>  include/linux/oid_registry.h              |  6 ++++++
>  8 files changed, 95 insertions(+), 1 deletion(-)
> 
> diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c
> index f5d85b47fcc6..3bc090b8adef 100644
> --- a/crypto/asymmetric_keys/public_key.c
> +++ b/crypto/asymmetric_keys/public_key.c
> @@ -45,6 +45,7 @@ void public_key_free(struct public_key *key)
>  {
>  	if (key) {
>  		kfree(key->key);
> +		kfree(key->params);
>  		kfree(key);
>  	}
>  }
> @@ -124,6 +125,11 @@ static int software_key_query(const struct kernel_pkey_params *params,
>  	if (ret < 0)
>  		goto error_free_tfm;
>  
> +	ret = crypto_akcipher_set_params(tfm, pkey->algo, pkey->params,
> +					 pkey->paramlen);
> +	if (ret)
> +		goto error_free_tfm;
> +
>  	len = crypto_akcipher_maxsize(tfm);
>  	info->key_size = len * 8;
>  	info->max_data_size = len;
> @@ -182,6 +188,11 @@ static int software_key_eds_op(struct kernel_pkey_params *params,
>  	if (ret)
>  		goto error_free_req;
>  
> +	ret = crypto_akcipher_set_params(tfm, pkey->algo, pkey->params,
> +					 pkey->paramlen);
> +	if (ret)
> +		goto error_free_req;
> +
>  	sg_init_one(&in_sg, in, params->in_len);
>  	sg_init_one(&out_sg, out, params->out_len);
>  	akcipher_request_set_crypt(req, &in_sg, &out_sg, params->in_len,
> @@ -263,6 +274,11 @@ int public_key_verify_signature(const struct public_key *pkey,
>  	if (ret)
>  		goto error_free_req;
>  
> +	ret = crypto_akcipher_set_params(tfm, pkey->algo, pkey->params,
> +					 pkey->paramlen);
> +	if (ret)
> +		goto error_free_req;
> +
>  	ret = -ENOMEM;
>  	outlen = crypto_akcipher_maxsize(tfm);
>  	output = kmalloc(outlen, GFP_KERNEL);
> diff --git a/crypto/asymmetric_keys/x509.asn1 b/crypto/asymmetric_keys/x509.asn1
> index aae0cde414e2..5c9f4e4a5231 100644
> --- a/crypto/asymmetric_keys/x509.asn1
> +++ b/crypto/asymmetric_keys/x509.asn1
> @@ -22,7 +22,7 @@ CertificateSerialNumber ::= INTEGER
>  
>  AlgorithmIdentifier ::= SEQUENCE {
>  	algorithm		OBJECT IDENTIFIER ({ x509_note_OID }),
> -	parameters		ANY OPTIONAL
> +	parameters		ANY OPTIONAL ({ x509_note_params })
>  }
>  
>  Name ::= SEQUENCE OF RelativeDistinguishedName
> diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c
> index 991f4d735a4e..16d8936d143b 100644
> --- a/crypto/asymmetric_keys/x509_cert_parser.c
> +++ b/crypto/asymmetric_keys/x509_cert_parser.c
> @@ -26,6 +26,9 @@ struct x509_parse_context {
>  	const void	*cert_start;		/* Start of cert content */
>  	const void	*key;			/* Key data */
>  	size_t		key_size;		/* Size of key data */
> +	const void	*params;		/* Key parameters */
> +	size_t		params_size;		/* Size of key parameters */
> +	enum OID	key_algo;		/* Public key algorithm */
>  	enum OID	last_oid;		/* Last OID encountered */
>  	enum OID	algo_oid;		/* Algorithm OID */
>  	unsigned char	nr_mpi;			/* Number of MPIs stored */
> @@ -109,6 +112,13 @@ struct x509_certificate *x509_cert_parse(const void *data, size_t datalen)
>  
>  	cert->pub->keylen = ctx->key_size;
>  
> +	cert->pub->params = kmemdup(ctx->params, ctx->params_size, GFP_KERNEL);
> +	if (!cert->pub->params)
> +		goto error_decode;
> +
> +	cert->pub->paramlen = ctx->params_size;
> +	cert->pub->algo = ctx->key_algo;
> +
>  	/* Grab the signature bits */
>  	ret = x509_get_sig_params(cert);
>  	if (ret < 0)
> @@ -401,6 +411,23 @@ int x509_note_subject(void *context, size_t hdrlen,
>  }
>  
>  /*
> + * Extract parameters for particular keys
> + */
> +int x509_note_params(void *context, size_t hdrlen,
> +		     unsigned char tag,
> +		     const void *value, size_t vlen)
> +{
> +	struct x509_parse_context *ctx = context;
> +
> +	if (ctx->last_oid != OID_gost2012PublicKey256 &&
> +	    ctx->last_oid != OID_gost2012PublicKey512)
> +		return 0;
> +	ctx->params = value;
> +	ctx->params_size = vlen;
> +	return 0;
> +}
> +
> +/*
>   * Extract the data for the public key algorithm
>   */
>  int x509_extract_key_data(void *context, size_t hdrlen,

Missed one hunk, which set ctx->key_algo:

@@ -436,16 +449,21 @@ int x509_extract_key_data(void *context, size_t hdrlen,
 {
        struct x509_parse_context *ctx = context;

-       if (ctx->last_oid != OID_rsaEncryption)
+       ctx->key_algo = ctx->last_oid;
+       if (ctx->last_oid == OID_rsaEncryption)
+               ctx->cert->pub->pkey_algo = "rsa";
+       else if (ctx->last_oid == OID_gost2012PublicKey256 ||
+                ctx->last_oid == OID_gost2012PublicKey512)
+               ctx->cert->pub->pkey_algo = "ecrdsa";
+       else
                return -ENOPKG;

-       ctx->cert->pub->pkey_algo = "rsa";
-
        /* Discard the BIT STRING metadata */
        if (vlen < 1 || *(const u8 *)value != 0)
                return -EBADMSG;
        ctx->key = value + 1;
        ctx->key_size = vlen - 1;
+
        return 0;
 }

> diff --git a/crypto/testmgr.c b/crypto/testmgr.c
> index 0f684a414acb..a030526a6609 100644
> --- a/crypto/testmgr.c
> +++ b/crypto/testmgr.c
> @@ -2257,6 +2257,11 @@ static int test_akcipher_one(struct crypto_akcipher *tfm,
>  	if (err)
>  		goto free_req;
>  
> +	err = crypto_akcipher_set_params(tfm, vecs->algo, vecs->params,
> +					 vecs->param_len);
> +	if (err)
> +		goto free_req;
> +
>  	err = -ENOMEM;
>  	out_len_max = crypto_akcipher_maxsize(tfm);
>  	outbuf_enc = kzalloc(out_len_max, GFP_KERNEL);
> diff --git a/crypto/testmgr.h b/crypto/testmgr.h
> index e7e56a8febbc..9855da080eaf 100644
> --- a/crypto/testmgr.h
> +++ b/crypto/testmgr.h
> @@ -124,13 +124,16 @@ struct drbg_testvec {
>  
>  struct akcipher_testvec {
>  	const unsigned char *key;
> +	const unsigned char *params;
>  	const unsigned char *m;
>  	const unsigned char *c;
>  	unsigned int key_len;
> +	unsigned int param_len;
>  	unsigned int m_size;
>  	unsigned int c_size;
>  	bool public_key_vec;
>  	bool siggen_sigver_test;
> +	enum OID algo;
>  };
>  
>  struct kpp_testvec {
> diff --git a/include/crypto/akcipher.h b/include/crypto/akcipher.h
> index afac71119396..d6aba84ed2c4 100644
> --- a/include/crypto/akcipher.h
> +++ b/include/crypto/akcipher.h
> @@ -13,6 +13,7 @@
>  #ifndef _CRYPTO_AKCIPHER_H
>  #define _CRYPTO_AKCIPHER_H
>  #include <linux/crypto.h>
> +#include <linux/oid_registry.h>
>  
>  /**
>   * struct akcipher_request - public key request
> @@ -73,6 +74,9 @@ struct crypto_akcipher {
>   * @set_priv_key: Function invokes the algorithm specific set private key
>   *		function, which knows how to decode and interpret
>   *		the BER encoded private key
> + * @set_params: Function invokes the algorithm specific set parameters
> + *		function, which knows how to decode and interpret
> + *		the BER encoded public key
>   * @max_size:	Function returns dest buffer size required for a given key.
>   * @init:	Initialize the cryptographic transformation object.
>   *		This function is used to initialize the cryptographic
> @@ -98,6 +102,8 @@ struct akcipher_alg {
>  			   unsigned int keylen);
>  	int (*set_priv_key)(struct crypto_akcipher *tfm, const void *key,
>  			    unsigned int keylen);
> +	int (*set_params)(struct crypto_akcipher *tfm, enum OID algo,
> +			  const void *params, unsigned int paramlen);
>  	unsigned int (*max_size)(struct crypto_akcipher *tfm);
>  	int (*init)(struct crypto_akcipher *tfm);
>  	void (*exit)(struct crypto_akcipher *tfm);
> @@ -452,4 +458,31 @@ static inline int crypto_akcipher_set_priv_key(struct crypto_akcipher *tfm,
>  
>  	return alg->set_priv_key(tfm, key, keylen);
>  }
> +
> +/**
> + * crypto_akcipher_set_params() - Invoke set parameters operation
> + *
> + * Function invokes the algorithm specific set parameters function, which
> + * knows how to decode and interpret the encoded parameters
> + *
> + * @tfm:	tfm handle
> + * @algo:	OID of the key algorithm
> + * @params:	BER encoded key parameters
> + * @paramlen:	length of the parameters
> + *
> + * Return: zero on success; error code in case of error
> + */
> +static inline int crypto_akcipher_set_params(struct crypto_akcipher *tfm,
> +					     enum OID algo,
> +					     const void *params,
> +					     unsigned int paramlen)
> +{
> +	struct akcipher_alg *alg = crypto_akcipher_alg(tfm);
> +
> +	if (alg->set_params)
> +		return alg->set_params(tfm, algo, params, paramlen);
> +	if (!params || !paramlen)
> +		return 0;
> +	return -ENOTSUPP;
> +}
>  #endif
> diff --git a/include/crypto/public_key.h b/include/crypto/public_key.h
> index be626eac9113..712fe1214b5f 100644
> --- a/include/crypto/public_key.h
> +++ b/include/crypto/public_key.h
> @@ -15,6 +15,7 @@
>  #define _LINUX_PUBLIC_KEY_H
>  
>  #include <linux/keyctl.h>
> +#include <linux/oid_registry.h>
>  
>  /*
>   * Cryptographic data for the public-key subtype of the asymmetric key type.
> @@ -25,6 +26,9 @@
>  struct public_key {
>  	void *key;
>  	u32 keylen;
> +	enum OID algo;
> +	void *params;
> +	u32 paramlen;
>  	bool key_is_private;
>  	const char *id_type;
>  	const char *pkey_algo;
> diff --git a/include/linux/oid_registry.h b/include/linux/oid_registry.h
> index d2fa9ca42e9a..e2e323fd4826 100644
> --- a/include/linux/oid_registry.h
> +++ b/include/linux/oid_registry.h
> @@ -93,6 +93,12 @@ enum OID {
>  	OID_authorityKeyIdentifier,	/* 2.5.29.35 */
>  	OID_extKeyUsage,		/* 2.5.29.37 */
>  
> +	/* EC-RDSA */
> +	OID_gost2012PublicKey256,	/* 1.2.643.7.1.1.1.1 */
> +	OID_gost2012PublicKey512,	/* 1.2.643.7.1.1.1.2 */
> +	OID_gost2012Signature256,	/* 1.2.643.7.1.1.3.2 */
> +	OID_gost2012Signature512,	/* 1.2.643.7.1.1.3.3 */
> +
>  	OID__NR
>  };
>  
> -- 
> 2.11.0

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