Re: [PATCH] crypto: sm2 - remove unnecessary reset operations

[Herbert Xu]

On Thu, Oct 15, 2020 at 05:24:41PM +0800, Tianjia Zhang wrote:
> This is an algorithm optimization. The reset operation when
> setting the public key is repeated and redundant, so remove it.
> At the same time, `sm2_ecc_os2ec()` is optimized to make the
> function more simpler and more in line with the Linux code style.
> 
> Signed-off-by: Tianjia Zhang 
> ---
>  crypto/sm2.c | 75 
>  1 file changed, 29 insertions(+), 46 deletions(-)

Patch applied.  Thanks.
-- 
Email: Herbert Xu 
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

[PATCH] crypto: sm2 - remove unnecessary reset operations

[Tianjia Zhang]

This is an algorithm optimization. The reset operation when
setting the public key is repeated and redundant, so remove it.
At the same time, `sm2_ecc_os2ec()` is optimized to make the
function more simpler and more in line with the Linux code style.

Signed-off-by: Tianjia Zhang 
---
 crypto/sm2.c | 75 
 1 file changed, 29 insertions(+), 46 deletions(-)

diff --git a/crypto/sm2.c b/crypto/sm2.c
index 767e160333f6..b21addc3ac06 100644
--- a/crypto/sm2.c
+++ b/crypto/sm2.c
@@ -119,12 +119,6 @@ static void sm2_ec_ctx_deinit(struct mpi_ec_ctx *ec)
memset(ec, 0, sizeof(*ec));
 }
 
-static int sm2_ec_ctx_reset(struct mpi_ec_ctx *ec)
-{
-   sm2_ec_ctx_deinit(ec);
-   return sm2_ec_ctx_init(ec);
-}
-
 /* RESULT must have been initialized and is set on success to the
  * point given by VALUE.
  */
@@ -132,55 +126,48 @@ static int sm2_ecc_os2ec(MPI_POINT result, MPI value)
 {
int rc;
size_t n;
-   const unsigned char *buf;
-   unsigned char *buf_memory;
+   unsigned char *buf;
MPI x, y;
 
-   n = (mpi_get_nbits(value)+7)/8;
-   buf_memory = kmalloc(n, GFP_KERNEL);
-   rc = mpi_print(GCRYMPI_FMT_USG, buf_memory, n, , value);
-   if (rc) {
-   kfree(buf_memory);
-   return rc;
-   }
-   buf = buf_memory;
+   n = MPI_NBYTES(value);
+   buf = kmalloc(n, GFP_KERNEL);
+   if (!buf)
+   return -ENOMEM;
 
-   if (n < 1) {
-   kfree(buf_memory);
-   return -EINVAL;
-   }
-   if (*buf != 4) {
-   kfree(buf_memory);
-   return -EINVAL; /* No support for point compression.  */
-   }
-   if (((n-1)%2)) {
-   kfree(buf_memory);
-   return -EINVAL;
-   }
-   n = (n-1)/2;
+   rc = mpi_print(GCRYMPI_FMT_USG, buf, n, , value);
+   if (rc)
+   goto err_freebuf;
+
+   rc = -EINVAL;
+   if (n < 1 || ((n - 1) % 2))
+   goto err_freebuf;
+   /* No support for point compression */
+   if (*buf != 0x4)
+   goto err_freebuf;
+
+   rc = -ENOMEM;
+   n = (n - 1) / 2;
x = mpi_read_raw_data(buf + 1, n);
-   if (!x) {
-   kfree(buf_memory);
-   return -ENOMEM;
-   }
+   if (!x)
+   goto err_freebuf;
y = mpi_read_raw_data(buf + 1 + n, n);
-   kfree(buf_memory);
-   if (!y) {
-   mpi_free(x);
-   return -ENOMEM;
-   }
+   if (!y)
+   goto err_freex;
 
mpi_normalize(x);
mpi_normalize(y);
-
mpi_set(result->x, x);
mpi_set(result->y, y);
mpi_set_ui(result->z, 1);
 
-   mpi_free(x);
-   mpi_free(y);
+   rc = 0;
 
-   return 0;
+   mpi_free(y);
+err_freex:
+   mpi_free(x);
+err_freebuf:
+   kfree(buf);
+   return rc;
 }
 
 struct sm2_signature_ctx {
@@ -399,10 +386,6 @@ static int sm2_set_pub_key(struct crypto_akcipher *tfm,
MPI a;
int rc;
 
-   rc = sm2_ec_ctx_reset(ec);
-   if (rc)
-   return rc;
-
ec->Q = mpi_point_new(0);
if (!ec->Q)
return -ENOMEM;
-- 
2.19.1.3.ge56e4f7