Messages in this thread | | | Subject | Re: [PATCH v6 7/8] X.509: support OSCCA sm2-with-sm3 certificate verification | From | Tianjia Zhang <> | Date | Mon, 14 Sep 2020 14:34:32 +0800 |
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Hi Gilad,
On 9/13/20 3:12 PM, Gilad Ben-Yossef wrote: > Hi, > > > On Thu, Sep 3, 2020 at 4:13 PM Tianjia Zhang > <tianjia.zhang@linux.alibaba.com> wrote: >> >> The digital certificate format based on SM2 crypto algorithm as >> specified in GM/T 0015-2012. It was published by State Encryption >> Management Bureau, China. >> >> The method of generating Other User Information is defined as >> ZA=H256(ENTLA || IDA || a || b || xG || yG || xA || yA), it also >> specified in https://tools.ietf.org/html/draft-shen-sm2-ecdsa-02. >> >> The x509 certificate supports sm2-with-sm3 type certificate >> verification. Because certificate verification requires ZA >> in addition to tbs data, ZA also depends on elliptic curve >> parameters and public key data, so you need to access tbs in sig >> and calculate ZA. Finally calculate the digest of the >> signature and complete the verification work. The calculation >> process of ZA is declared in specifications GM/T 0009-2012 >> and GM/T 0003.2-2012. >> >> Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com> >> Tested-by: Xufeng Zhang <yunbo.xufeng@linux.alibaba.com> >> --- >> crypto/asymmetric_keys/Makefile | 1 + >> crypto/asymmetric_keys/public_key.c | 6 +++ >> crypto/asymmetric_keys/public_key_sm2.c | 61 ++++++++++++++++++++++++ >> crypto/asymmetric_keys/x509_public_key.c | 3 ++ >> include/crypto/public_key.h | 15 ++++++ >> 5 files changed, 86 insertions(+) >> create mode 100644 crypto/asymmetric_keys/public_key_sm2.c >> >> diff --git a/crypto/asymmetric_keys/Makefile b/crypto/asymmetric_keys/Makefile >> index 28b91adba2ae..1a99ea5acb6b 100644 >> --- a/crypto/asymmetric_keys/Makefile >> +++ b/crypto/asymmetric_keys/Makefile >> @@ -11,6 +11,7 @@ asymmetric_keys-y := \ >> signature.o >> >> obj-$(CONFIG_ASYMMETRIC_PUBLIC_KEY_SUBTYPE) += public_key.o >> +obj-$(CONFIG_ASYMMETRIC_PUBLIC_KEY_SUBTYPE) += public_key_sm2.o >> obj-$(CONFIG_ASYMMETRIC_TPM_KEY_SUBTYPE) += asym_tpm.o >> >> # >> diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c >> index d8410ffd7f12..1d0492098bbd 100644 >> --- a/crypto/asymmetric_keys/public_key.c >> +++ b/crypto/asymmetric_keys/public_key.c >> @@ -299,6 +299,12 @@ int public_key_verify_signature(const struct public_key *pkey, >> if (ret) >> goto error_free_key; >> >> + if (strcmp(sig->pkey_algo, "sm2") == 0 && sig->data_size) { >> + ret = cert_sig_digest_update(sig, tfm); >> + if (ret) >> + goto error_free_key; >> + } >> + >> sg_init_table(src_sg, 2); >> sg_set_buf(&src_sg[0], sig->s, sig->s_size); >> sg_set_buf(&src_sg[1], sig->digest, sig->digest_size); >> diff --git a/crypto/asymmetric_keys/public_key_sm2.c b/crypto/asymmetric_keys/public_key_sm2.c >> new file mode 100644 >> index 000000000000..7325cf21dbb4 >> --- /dev/null >> +++ b/crypto/asymmetric_keys/public_key_sm2.c >> @@ -0,0 +1,61 @@ >> +/* SPDX-License-Identifier: GPL-2.0-or-later */ >> +/* >> + * asymmetric public-key algorithm for SM2-with-SM3 certificate >> + * as specified by OSCCA GM/T 0003.1-2012 -- 0003.5-2012 SM2 and >> + * described at https://tools.ietf.org/html/draft-shen-sm2-ecdsa-02 >> + * >> + * Copyright (c) 2020, Alibaba Group. >> + * Authors: Tianjia Zhang <tianjia.zhang@linux.alibaba.com> >> + */ >> + >> +#include <crypto/sm3_base.h> >> +#include <crypto/sm2.h> >> +#include <crypto/public_key.h> >> + >> +#if IS_REACHABLE(CONFIG_CRYPTO_SM2) >> + >> +int cert_sig_digest_update(const struct public_key_signature *sig, >> + struct crypto_akcipher *tfm_pkey) >> +{ >> + struct crypto_shash *tfm; >> + struct shash_desc *desc; >> + size_t desc_size; >> + unsigned char dgst[SM3_DIGEST_SIZE]; >> + int ret; >> + >> + BUG_ON(!sig->data); >> + >> + ret = sm2_compute_z_digest(tfm_pkey, SM2_DEFAULT_USERID, >> + SM2_DEFAULT_USERID_LEN, dgst); >> + if (ret) >> + return ret; >> + >> + tfm = crypto_alloc_shash(sig->hash_algo, 0, 0); >> + if (IS_ERR(tfm)) >> + return PTR_ERR(tfm); >> + >> + desc_size = crypto_shash_descsize(tfm) + sizeof(*desc); >> + desc = kzalloc(desc_size, GFP_KERNEL); >> + if (!desc) >> + goto error_free_tfm; >> + >> + desc->tfm = tfm; >> + >> + ret = crypto_shash_init(desc); >> + if (ret < 0) >> + goto error_free_desc; >> + >> + ret = crypto_shash_update(desc, dgst, SM3_DIGEST_SIZE); >> + if (ret < 0) >> + goto error_free_desc; >> + >> + ret = crypto_shash_finup(desc, sig->data, sig->data_size, sig->digest); > > It looks like you are doing a separate init, update, finup every time > - I would consider using crypto_shash_digest() in one go. > > In fact, considering the fact that you are allocating a tfm just for > this use and then releasing it, I would consider switching to > crypto_shash_tfm_digest() and dropping the kzalloc all together. > > This should simplify the code a bit. > > Other than that I don't have anything smart to say :-) > > Gilad >
The hash calculation here includes two parts of data, 'dgst' and 'sig->data'. The last call is 'finup()' not 'final()'. I understand that it should not be possible to use 'crypto_shash_tfm_digest()' This kind of function is simplified.
If a new scope is added, the assignment of desc can be optimized, as follows: ``` do { SHASH_DESC_ON_STACK(desc, tfm); desc->tfm = tfm;
/* ... */ } while (0); ``` However, the kernel code may not accept this style. What is your opinion?
Thanks, Tianjia
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