digsig: remove unnecessary memory allocation and copying
In existing use case, copying of the decoded data is unnecessary in
pkcs_1_v1_5_decode_emsa. It is just enough to get pointer to the message.
Removing copying and extra buffer allocation.
Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
diff --git a/lib/digsig.c b/lib/digsig.c
index 8c0e629..0103c5b 100644
--- a/lib/digsig.c
+++ b/lib/digsig.c
@@ -30,11 +30,10 @@
static struct crypto_shash *shash;
-static int pkcs_1_v1_5_decode_emsa(const unsigned char *msg,
- unsigned long msglen,
- unsigned long modulus_bitlen,
- unsigned char *out,
- unsigned long *outlen)
+static const char *pkcs_1_v1_5_decode_emsa(const unsigned char *msg,
+ unsigned long msglen,
+ unsigned long modulus_bitlen,
+ unsigned long *outlen)
{
unsigned long modulus_len, ps_len, i;
@@ -42,11 +41,11 @@
/* test message size */
if ((msglen > modulus_len) || (modulus_len < 11))
- return -EINVAL;
+ return NULL;
/* separate encoded message */
- if ((msg[0] != 0x00) || (msg[1] != (unsigned char)1))
- return -EINVAL;
+ if (msg[0] != 0x00 || msg[1] != 0x01)
+ return NULL;
for (i = 2; i < modulus_len - 1; i++)
if (msg[i] != 0xFF)
@@ -56,19 +55,13 @@
if (msg[i] != 0)
/* There was no octet with hexadecimal value 0x00
to separate ps from m. */
- return -EINVAL;
+ return NULL;
ps_len = i - 2;
- if (*outlen < (msglen - (2 + ps_len + 1))) {
- *outlen = msglen - (2 + ps_len + 1);
- return -EOVERFLOW;
- }
-
*outlen = (msglen - (2 + ps_len + 1));
- memcpy(out, &msg[2 + ps_len + 1], *outlen);
- return 0;
+ return msg + 2 + ps_len + 1;
}
/*
@@ -83,7 +76,8 @@
unsigned long mlen, mblen;
unsigned nret, l;
int head, i;
- unsigned char *out1 = NULL, *out2 = NULL;
+ unsigned char *out1 = NULL;
+ const char *m;
MPI in = NULL, res = NULL, pkey[2];
uint8_t *p, *datap, *endp;
struct user_key_payload *ukp;
@@ -120,7 +114,7 @@
}
mblen = mpi_get_nbits(pkey[0]);
- mlen = (mblen + 7)/8;
+ mlen = DIV_ROUND_UP(mblen, 8);
if (mlen == 0)
goto err;
@@ -129,10 +123,6 @@
if (!out1)
goto err;
- out2 = kzalloc(mlen, GFP_KERNEL);
- if (!out2)
- goto err;
-
nret = siglen;
in = mpi_read_from_buffer(sig, &nret);
if (!in)
@@ -162,18 +152,15 @@
memset(out1, 0, head);
memcpy(out1 + head, p, l);
- err = pkcs_1_v1_5_decode_emsa(out1, len, mblen, out2, &len);
- if (err)
- goto err;
+ m = pkcs_1_v1_5_decode_emsa(out1, len, mblen, &len);
- if (len != hlen || memcmp(out2, h, hlen))
+ if (!m || len != hlen || memcmp(m, h, hlen))
err = -EINVAL;
err:
mpi_free(in);
mpi_free(res);
kfree(out1);
- kfree(out2);
while (--i >= 0)
mpi_free(pkey[i]);
err1: