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KEYS: asymmetric: Move sm2 code into x509_public_key
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The sm2 certificate requires a modified digest.  Move the code
for the hashing from the signature verification path into the
code where we generate the digest.

Signed-off-by: Herbert Xu <[email protected]>
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@herbertx
herbertx committed Jun 23, 2023
1 parent b6d0695 commit e5221fa
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Showing 5 changed files with 94 additions and 122 deletions.
67 changes: 0 additions & 67 deletions crypto/asymmetric_keys/public_key.c
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Original file line number Diff line number Diff line change
Expand Up @@ -18,8 +18,6 @@
#include <keys/asymmetric-subtype.h>
#include <crypto/public_key.h>
#include <crypto/akcipher.h>
#include <crypto/sm2.h>
#include <crypto/sm3_base.h>

MODULE_DESCRIPTION("In-software asymmetric public-key subtype");
MODULE_AUTHOR("Red Hat, Inc.");
Expand Down Expand Up @@ -312,65 +310,6 @@ static int software_key_eds_op(struct kernel_pkey_params *params,
return ret;
}

#if IS_REACHABLE(CONFIG_CRYPTO_SM2)
static 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);

/* SM2 signatures always use the SM3 hash algorithm */
if (!sig->hash_algo || strcmp(sig->hash_algo, "sm3") != 0)
return -EINVAL;

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) {
ret = -ENOMEM;
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);

error_free_desc:
kfree(desc);
error_free_tfm:
crypto_free_shash(tfm);
return ret;
}
#else
static inline int cert_sig_digest_update(
const struct public_key_signature *sig,
struct crypto_akcipher *tfm_pkey)
{
return -ENOTSUPP;
}
#endif /* ! IS_REACHABLE(CONFIG_CRYPTO_SM2) */

/*
* Verify a signature using a public key.
*/
Expand Down Expand Up @@ -438,12 +377,6 @@ int public_key_verify_signature(const struct public_key *pkey,
if (ret)
goto error_free_key;

if (strcmp(pkey->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);
Expand Down
29 changes: 21 additions & 8 deletions crypto/asymmetric_keys/x509_public_key.c
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Original file line number Diff line number Diff line change
Expand Up @@ -6,13 +6,15 @@
*/

#define pr_fmt(fmt) "X.509: "fmt
#include <crypto/hash.h>
#include <crypto/sm2.h>
#include <keys/asymmetric-parser.h>
#include <keys/asymmetric-subtype.h>
#include <keys/system_keyring.h>
#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 <linux/string.h>
#include "asymmetric_keys.h"
#include "x509_parser.h"

Expand All @@ -30,9 +32,6 @@ int x509_get_sig_params(struct x509_certificate *cert)

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

sig->data = cert->tbs;
sig->data_size = cert->tbs_size;

sig->s = kmemdup(cert->raw_sig, cert->raw_sig_size, GFP_KERNEL);
if (!sig->s)
return -ENOMEM;
Expand Down Expand Up @@ -65,7 +64,21 @@ int x509_get_sig_params(struct x509_certificate *cert)

desc->tfm = tfm;

ret = crypto_shash_digest(desc, cert->tbs, cert->tbs_size, sig->digest);
if (strcmp(cert->pub->pkey_algo, "sm2") == 0) {
ret = strcmp(sig->hash_algo, "sm3") != 0 ? -EINVAL :
crypto_shash_init(desc) ?:
sm2_compute_z_digest(desc, cert->pub->key,
cert->pub->keylen, sig->digest) ?:
crypto_shash_init(desc) ?:
crypto_shash_update(desc, sig->digest,
sig->digest_size) ?:
crypto_shash_finup(desc, cert->tbs, cert->tbs_size,
sig->digest);
} else {
ret = crypto_shash_digest(desc, cert->tbs, cert->tbs_size,
sig->digest);
}

if (ret < 0)
goto error_2;

Expand Down
106 changes: 70 additions & 36 deletions crypto/sm2.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -13,11 +13,14 @@
#include <crypto/internal/akcipher.h>
#include <crypto/akcipher.h>
#include <crypto/hash.h>
#include <crypto/sm3.h>
#include <crypto/rng.h>
#include <crypto/sm2.h>
#include "sm2signature.asn1.h"

/* The default user id as specified in GM/T 0009-2012 */
#define SM2_DEFAULT_USERID "1234567812345678"
#define SM2_DEFAULT_USERID_LEN 16

#define MPI_NBYTES(m) ((mpi_get_nbits(m) + 7) / 8)

struct ecc_domain_parms {
Expand Down Expand Up @@ -60,6 +63,9 @@ static const struct ecc_domain_parms sm2_ecp = {
.h = 1
};

static int __sm2_set_pub_key(struct mpi_ec_ctx *ec,
const void *key, unsigned int keylen);

static int sm2_ec_ctx_init(struct mpi_ec_ctx *ec)
{
const struct ecc_domain_parms *ecp = &sm2_ecp;
Expand Down Expand Up @@ -213,85 +219,105 @@ int sm2_get_signature_s(void *context, size_t hdrlen, unsigned char tag,
return 0;
}

static int sm2_z_digest_update(struct sm3_state *sctx,
MPI m, unsigned int pbytes)
static int sm2_z_digest_update(struct shash_desc *desc,
MPI m, unsigned int pbytes)
{
static const unsigned char zero[32];
unsigned char *in;
unsigned int inlen;
int err;

in = mpi_get_buffer(m, &inlen, NULL);
if (!in)
return -EINVAL;

if (inlen < pbytes) {
/* padding with zero */
sm3_update(sctx, zero, pbytes - inlen);
sm3_update(sctx, in, inlen);
err = crypto_shash_update(desc, zero, pbytes - inlen) ?:
crypto_shash_update(desc, in, inlen);
} else if (inlen > pbytes) {
/* skip the starting zero */
sm3_update(sctx, in + inlen - pbytes, pbytes);
err = crypto_shash_update(desc, in + inlen - pbytes, pbytes);
} else {
sm3_update(sctx, in, inlen);
err = crypto_shash_update(desc, in, inlen);
}

kfree(in);
return 0;
return err;
}

static int sm2_z_digest_update_point(struct sm3_state *sctx,
MPI_POINT point, struct mpi_ec_ctx *ec, unsigned int pbytes)
static int sm2_z_digest_update_point(struct shash_desc *desc,
MPI_POINT point, struct mpi_ec_ctx *ec,
unsigned int pbytes)
{
MPI x, y;
int ret = -EINVAL;

x = mpi_new(0);
y = mpi_new(0);

if (!mpi_ec_get_affine(x, y, point, ec) &&
!sm2_z_digest_update(sctx, x, pbytes) &&
!sm2_z_digest_update(sctx, y, pbytes))
ret = 0;
ret = mpi_ec_get_affine(x, y, point, ec) ? -EINVAL :
sm2_z_digest_update(desc, x, pbytes) ?:
sm2_z_digest_update(desc, y, pbytes);

mpi_free(x);
mpi_free(y);
return ret;
}

int sm2_compute_z_digest(struct crypto_akcipher *tfm,
const unsigned char *id, size_t id_len,
unsigned char dgst[SM3_DIGEST_SIZE])
int sm2_compute_z_digest(struct shash_desc *desc,
const void *key, unsigned int keylen, void *dgst)
{
struct mpi_ec_ctx *ec = akcipher_tfm_ctx(tfm);
uint16_t bits_len;
unsigned char entl[2];
struct sm3_state sctx;
struct mpi_ec_ctx *ec;
unsigned int bits_len;
unsigned int pbytes;
u8 entl[2];
int err;

if (id_len > (USHRT_MAX / 8) || !ec->Q)
return -EINVAL;
ec = kmalloc(sizeof(*ec), GFP_KERNEL);
if (!ec)
return -ENOMEM;

err = __sm2_set_pub_key(ec, key, keylen);
if (err)
goto out_free_ec;

bits_len = (uint16_t)(id_len * 8);
bits_len = SM2_DEFAULT_USERID_LEN * 8;
entl[0] = bits_len >> 8;
entl[1] = bits_len & 0xff;

pbytes = MPI_NBYTES(ec->p);

/* ZA = H256(ENTLA | IDA | a | b | xG | yG | xA | yA) */
sm3_init(&sctx);
sm3_update(&sctx, entl, 2);
sm3_update(&sctx, id, id_len);

if (sm2_z_digest_update(&sctx, ec->a, pbytes) ||
sm2_z_digest_update(&sctx, ec->b, pbytes) ||
sm2_z_digest_update_point(&sctx, ec->G, ec, pbytes) ||
sm2_z_digest_update_point(&sctx, ec->Q, ec, pbytes))
return -EINVAL;
err = crypto_shash_init(desc);
if (err)
goto out_deinit_ec;

sm3_final(&sctx, dgst);
return 0;
err = crypto_shash_update(desc, entl, 2);
if (err)
goto out_deinit_ec;

err = crypto_shash_update(desc, SM2_DEFAULT_USERID,
SM2_DEFAULT_USERID_LEN);
if (err)
goto out_deinit_ec;

err = sm2_z_digest_update(desc, ec->a, pbytes) ?:
sm2_z_digest_update(desc, ec->b, pbytes) ?:
sm2_z_digest_update_point(desc, ec->G, ec, pbytes) ?:
sm2_z_digest_update_point(desc, ec->Q, ec, pbytes);
if (err)
goto out_deinit_ec;

err = crypto_shash_final(desc, dgst);

out_deinit_ec:
sm2_ec_ctx_deinit(ec);
out_free_ec:
kfree(ec);
return err;
}
EXPORT_SYMBOL(sm2_compute_z_digest);
EXPORT_SYMBOL_GPL(sm2_compute_z_digest);

static int _sm2_verify(struct mpi_ec_ctx *ec, MPI hash, MPI sig_r, MPI sig_s)
{
Expand Down Expand Up @@ -391,6 +417,14 @@ static int sm2_set_pub_key(struct crypto_akcipher *tfm,
const void *key, unsigned int keylen)
{
struct mpi_ec_ctx *ec = akcipher_tfm_ctx(tfm);

return __sm2_set_pub_key(ec, key, keylen);

}

static int __sm2_set_pub_key(struct mpi_ec_ctx *ec,
const void *key, unsigned int keylen)
{
MPI a;
int rc;

Expand Down
2 changes: 0 additions & 2 deletions include/crypto/public_key.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -48,8 +48,6 @@ struct public_key_signature {
const char *pkey_algo;
const char *hash_algo;
const char *encoding;
const void *data;
unsigned int data_size;
};

extern void public_key_signature_free(struct public_key_signature *sig);
Expand Down
12 changes: 3 additions & 9 deletions include/crypto/sm2.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -11,15 +11,9 @@
#ifndef _CRYPTO_SM2_H
#define _CRYPTO_SM2_H

#include <crypto/sm3.h>
#include <crypto/akcipher.h>
struct shash_desc;

/* The default user id as specified in GM/T 0009-2012 */
#define SM2_DEFAULT_USERID "1234567812345678"
#define SM2_DEFAULT_USERID_LEN 16

extern int sm2_compute_z_digest(struct crypto_akcipher *tfm,
const unsigned char *id, size_t id_len,
unsigned char dgst[SM3_DIGEST_SIZE]);
int sm2_compute_z_digest(struct shash_desc *desc,
const void *key, unsigned int keylen, void *dgst);

#endif /* _CRYPTO_SM2_H */

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