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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>
This commit is contained in:
Dmitry Kasatkin 2013-01-30 11:30:05 +02:00 committed by James Morris
parent 5a73fcfa88
commit 26d438457e
1 changed files with 14 additions and 27 deletions
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41
lib/digsig.c
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@ -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 @@ static int pkcs_1_v1_5_decode_emsa(const unsigned char *msg,
/* 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 @@ static int pkcs_1_v1_5_decode_emsa(const unsigned char *msg,
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 @@ static int digsig_verify_rsa(struct key *key,
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 @@ static int digsig_verify_rsa(struct key *key,
}
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 @@ static int digsig_verify_rsa(struct key *key,
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 @@ static int digsig_verify_rsa(struct key *key,
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: