Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752427Ab3IRJHi (ORCPT ); Wed, 18 Sep 2013 05:07:38 -0400 Received: from smtp.nue.novell.com ([195.135.221.5]:53521 "EHLO smtp.nue.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752386Ab3IRJHf (ORCPT ); Wed, 18 Sep 2013 05:07:35 -0400 Subject: Re: [PATCH V4 02/15] asymmetric keys: implement EMSA_PKCS1-v1_5-ENCODE in rsa From: joeyli To: Dmitry Kasatkin Cc: "linux-kernel@vger.kernel.org" , linux-security-module@vger.kernel.org, linux-efi@vger.kernel.org, linux-pm@vger.kernel.org, linux-crypto@vger.kernel.org, opensuse-kernel@opensuse.org, David Howells , "Rafael J. Wysocki" , Matthew Garrett , Len Brown , Pavel Machek , Josh Boyer , Vojtech Pavlik , Matt Fleming , James Bottomley , Greg KH , JKosina@suse.com, Rusty Russell , Herbert Xu , "David S. Miller" , "H. Peter Anvin" , Michal Marek , Gary Lin , Vivek Goyal In-Reply-To: References: <1379206621-18639-1-git-send-email-jlee@suse.com> <1379206621-18639-3-git-send-email-jlee@suse.com> Content-Type: text/plain; charset="UTF-8" Date: Wed, 18 Sep 2013 04:08:00 -0500 Message-ID: <1379495280.21947.311.camel@linux-s257.site> Mime-Version: 1.0 X-Mailer: Evolution 2.28.2 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 11361 Lines: 333 Hi Dmitry, First, thanks for your time to review my patches! 於 二，2013-09-17 於 16:51 -0500，Dmitry Kasatkin 提到： > Hello, > > > On Sat, Sep 14, 2013 at 7:56 PM, Lee, Chun-Yi wrote: > > Implement EMSA_PKCS1-v1_5-ENCODE [RFC3447 sec 9.2] in rsa.c. It's the > > first step of signature generation operation (RSASSA-PKCS1-v1_5-SIGN). > > > > This patch is temporary set emLen to pks->k, and temporary set EM to > > pks->S for debugging. We will replace the above values to real signature > > after implement RSASP1. > > > > The naming of EMSA_PKCS1_v1_5_ENCODE and the variables used in this function > > accord PKCS#1 spec but not follow kernel naming convention, it useful when look > > at them with spec. > > > > Reference: ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-1v2/pkcs1ietffinal.txt > > Reference: http://www.emc.com/collateral/white-papers/h11300-pkcs-1v2-2-rsa-cryptography-standard-wp.pdf > > > > V2: > > - Clean up naming of variable: replace _EM by EM, replace EM by EM_tmp. > > - Add comment to EMSA_PKCS1-v1_5-ENCODE function. > > > > Cc: Pavel Machek > > Reviewed-by: Jiri Kosina > > Signed-off-by: Lee, Chun-Yi > > --- > > crypto/asymmetric_keys/rsa.c | 163 +++++++++++++++++++++++++++++++++++++++++- > > include/crypto/public_key.h | 2 + > > 2 files changed, 164 insertions(+), 1 deletions(-) > > > > diff --git a/crypto/asymmetric_keys/rsa.c b/crypto/asymmetric_keys/rsa.c > > index 47f3be4..352ba45 100644 > > --- a/crypto/asymmetric_keys/rsa.c > > +++ b/crypto/asymmetric_keys/rsa.c > > @@ -13,6 +13,7 @@ > > #include > > #include > > #include > > +#include > > #include "public_key.h" > > #include "private_key.h" > > > > @@ -152,6 +153,132 @@ static int RSA_I2OSP(MPI x, size_t xLen, u8 **_X) > > } > > > > /* > > + * EMSA_PKCS1-v1_5-ENCODE [RFC3447 sec 9.2] > > + * @M: message to be signed, an octet string > > + * @emLen: intended length in octets of the encoded message > > + * @hash_algo: hash function (option) > > + * @hash: true means hash M, otherwise M is already a digest > > + * @EM: encoded message, an octet string of length emLen > > + * > > + * This function is a implementation of the EMSA-PKCS1-v1_5 encoding operation > > + * in RSA PKCS#1 spec. It used by the signautre generation operation of > > + * RSASSA-PKCS1-v1_5 to encode message M to encoded message EM. > > + * > > + * The variables used in this function accord PKCS#1 spec but not follow kernel > > + * naming convention, it useful when look at them with spec. > > + */ > > +static int EMSA_PKCS1_v1_5_ENCODE(const u8 *M, size_t emLen, > > + enum pkey_hash_algo hash_algo, const bool hash, > > + u8 **EM, struct public_key_signature *pks) > > +{ > > + u8 *digest; > > + struct crypto_shash *tfm; > > + struct shash_desc *desc; > > + size_t digest_size, desc_size; > > + size_t tLen; > > + u8 *T, *PS, *EM_tmp; > > + int i, ret; > > + > > + pr_info("EMSA_PKCS1_v1_5_ENCODE start\n"); > > + > > + if (!RSA_ASN1_templates[hash_algo].data) > > What about checking hash_algo against PKEY_HASH__LAST, or it relies on > the caller? > Yes, check PKEY_HASH__LAST is more easy and clear, I will change it. Thanks! > > > + ret = -ENOTSUPP; > > + else > > + pks->pkey_hash_algo = hash_algo; > > + > > + /* 1) Apply the hash function to the message M to produce a hash value H */ > > + tfm = crypto_alloc_shash(pkey_hash_algo[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); > > + > > + ret = -ENOMEM; > > + > > + digest = kzalloc(digest_size + desc_size, GFP_KERNEL); > > + if (!digest) > > + goto error_digest; > > + pks->digest = digest; > > + pks->digest_size = digest_size; > > + > > Ok. You allocated tfm to get hash size, right? > > But why do you allocate descriptor even it might not be needed? > You are right, I should skip the code of allocate descriptor when the hash is supported. I will modified it. Thanks! > > + if (hash) { > > + desc = (void *) digest + digest_size; > > + desc->tfm = tfm; > > + desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP; > > + > > + ret = crypto_shash_init(desc); > > + if (ret < 0) > > + goto error_shash; > > + ret = crypto_shash_finup(desc, M, sizeof(M), pks->digest); > > This is I completely fail to understand... You expect sizeof(M) to be > the message length????? > Have you ever tested it? > Sigh! I just checked my test program for this code path, this stupid problem causes by my test program doesn't feed the right hash result that should used to verify signature. So, I didn't capture this bug. And, the hibernate signature check mechanism doesn't run into this code path because the hash generation is done by hibernate code but not in here. So, I also didn't find this problem when running hibernate check. Appreciate for your point out! I just fix it in next patch version. > > + if (ret < 0) > > + goto error_shash; > > + } else { > > + memcpy(pks->digest, M, pks->digest_size); > > + pks->digest_size = digest_size; > > + } > > Does caller use pks->digest and pks->digest_size after return? > I think it needs encoded value, not the hash... > So why do you pass pks? > I put the signature MPI to pks->rsa.s, and put the encoded signature to pks->S. So caller can grab encoded signature. I also pass the pks->digest and pks->digest_size to caller for reference. Then caller can simply feed this pks to RSA_verify_signature() for verify the signature result, don't need generate hash again. > > > > + crypto_free_shash(tfm); > > + > > + /* 2) Encode the algorithm ID for the hash function and the hash value into > > + * an ASN.1 value of type DigestInfo with the DER. Let T be the DER encoding of > > + * the DigestInfo value and let tLen be the length in octets of T. > > + */ > > + tLen = RSA_ASN1_templates[hash_algo].size + pks->digest_size; > > + T = kmalloc(tLen, GFP_KERNEL); > > + if (!T) > > + goto error_T; > > + > > Why do you need T and PS memory allocations at all? > You need only EM_tmp allocation and copy directly to the destination... > OK, I will change the code to allocate T and PS size in EM_tmp. > > > + memcpy(T, RSA_ASN1_templates[hash_algo].data, RSA_ASN1_templates[hash_algo].size); > > + memcpy(T + RSA_ASN1_templates[hash_algo].size, pks->digest, pks->digest_size); > > + > > + /* 3) check If emLen < tLen + 11, output "intended encoded message length too short" */ > > + if (emLen < tLen + 11) { > > + ret = -EINVAL; > > + goto error_emLen; > > + } > > + > > + /* 4) Generate an octet string PS consisting of emLen - tLen - 3 octets with 0xff. */ > > + PS = kmalloc(emLen - tLen - 3, GFP_KERNEL); > > + if (!PS) > > + goto error_P; > > + > > ditto OK, I will allocate PS with EM_tmp. Thanks! > > > + for (i = 0; i < (emLen - tLen - 3); i++) > > + PS[i] = 0xff; > > + > > + /* 5) Concatenate PS, the DER encoding T, and other padding to form the encoded > > + * message EM as EM = 0x00 || 0x01 || PS || 0x00 || T > > + */ > > + EM_tmp = kmalloc(3 + emLen - tLen - 3 + tLen, GFP_KERNEL); > > + if (!EM_tmp) > > + goto error_EM; > > + > > + EM_tmp[0] = 0x00; > > + EM_tmp[1] = 0x01; > > + memcpy(EM_tmp + 2, PS, emLen - tLen - 3); > > + EM_tmp[2 + emLen - tLen - 3] = 0x00; > > + memcpy(EM_tmp + 2 + emLen - tLen - 3 + 1, T, tLen); > > + > > + *EM = EM_tmp; > > + > > + kfree(PS); > > + kfree(T); > > get rid of it... > OK! > > - Dmitry > > > + > > + return 0; > > + > > +error_EM: > > + kfree(PS); > > +error_P: > > +error_emLen: > > + kfree(T); > > +error_T: > > +error_shash: > > + kfree(digest); > > +error_digest: > > + crypto_free_shash(tfm); > > + return ret; > > +} > > + > > +/* > > * Perform the RSA signature verification. > > * @H: Value of hash of data and metadata > > * @EM: The computed signature value > > @@ -275,9 +402,43 @@ static struct public_key_signature *RSA_generate_signature( > > const struct private_key *key, u8 *M, > > enum pkey_hash_algo hash_algo, const bool hash) > > { > > + struct public_key_signature *pks; > > + u8 *EM = NULL; > > + size_t emLen; > > + int ret; > > + > > pr_info("RSA_generate_signature start\n"); > > > > - return 0; > > + ret = -ENOMEM; > > + pks = kzalloc(sizeof(*pks), GFP_KERNEL); > > + if (!pks) > > + goto error_no_pks; > > + > > + /* 1): EMSA-PKCS1-v1_5 encoding: */ > > + /* Use the private key modulus size to be EM length */ > > + emLen = mpi_get_nbits(key->rsa.n); > > + emLen = (emLen + 7) / 8; > > + > > + ret = EMSA_PKCS1_v1_5_ENCODE(M, emLen, hash_algo, hash, &EM, pks); > > + if (ret < 0) > > + goto error_v1_5_encode; > > + > > + /* TODO 2): m = OS2IP (EM) */ > > + > > + /* TODO 3): s = RSASP1 (K, m) */ > > + > > + /* TODO 4): S = I2OSP (s, k) */ > > + > > + /* TODO: signature S to a u8* S or set to sig->rsa.s? */ > > + pks->S = EM; /* TODO: temporary set S to EM */ > > + > > + return pks; > > + > > +error_v1_5_encode: > > + kfree(pks); > > +error_no_pks: > > + pr_info("<==%s() = %d\n", __func__, ret); > > + return ERR_PTR(ret); > > } > > > > const struct public_key_algorithm RSA_public_key_algorithm = { > > diff --git a/include/crypto/public_key.h b/include/crypto/public_key.h > > index d44b29f..1cdf457 100644 > > --- a/include/crypto/public_key.h > > +++ b/include/crypto/public_key.h > > @@ -110,6 +110,8 @@ extern void public_key_destroy(void *payload); > > struct public_key_signature { > > u8 *digest; > > u8 digest_size; /* Number of bytes in digest */ > > + u8 *S; /* signature S of length k octets */ > > + size_t k; /* length k of signature S */ > > u8 nr_mpi; /* Occupancy of mpi[] */ > > enum pkey_hash_algo pkey_hash_algo : 8; > > union { > > -- > > 1.6.0.2 > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-crypto" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > Thanks a lot! Joey Lee -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/