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rsa/*: switch to BN_bn2binpad.

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Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5254)
This commit is contained in:
Andy Polyakov 2018-02-04 15:24:54 +01:00
parent 89d8aade5f
commit 582ad5d4d9
4 changed files with 64 additions and 59 deletions
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38
crypto/rsa/rsa_oaep.c
View File

@ -150,32 +150,40 @@ int RSA_padding_check_PKCS1_OAEP_mgf1(unsigned char *to, int tlen,
dblen = num - mdlen - 1;
db = OPENSSL_malloc(dblen);
em = OPENSSL_malloc(num);
if (db == NULL || em == NULL) {
if (db == NULL) {
RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP_MGF1, ERR_R_MALLOC_FAILURE);
goto cleanup;
}
/*
* Always do this zero-padding copy (even when num == flen) to avoid
* leaking that information. The copy still leaks some side-channel
* information, but it's impossible to have a fixed memory access
* pattern since we can't read out of the bounds of |from|.
*
* TODO(emilia): Consider porting BN_bn2bin_padded from BoringSSL.
*/
memset(em, 0, num);
memcpy(em + num - flen, from, flen);
if (flen != num) {
em = OPENSSL_zalloc(num);
if (em == NULL) {
RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP_MGF1,
ERR_R_MALLOC_FAILURE);
goto cleanup;
}
/*
* Caller is encouraged to pass zero-padded message created with
* BN_bn2binpad, but if it doesn't, we do this zero-padding copy
* to avoid leaking that information. The copy still leaks some
* side-channel information, but it's impossible to have a fixed
* memory access pattern since we can't read out of the bounds of
* |from|.
*/
memcpy(em + num - flen, from, flen);
from = em;
}
/*
* The first byte must be zero, however we must not leak if this is
* true. See James H. Manger, "A Chosen Ciphertext Attack on RSA
* Optimal Asymmetric Encryption Padding (OAEP) [...]", CRYPTO 2001).
*/
good = constant_time_is_zero(em[0]);
good = constant_time_is_zero(from[0]);
maskedseed = em + 1;
maskeddb = em + 1 + mdlen;
maskedseed = from + 1;
maskeddb = from + 1 + mdlen;
if (PKCS1_MGF1(seed, mdlen, maskeddb, dblen, mgf1md))
goto cleanup;

38
crypto/rsa/rsa_ossl.c
View File

@ -68,7 +68,7 @@ static int rsa_ossl_public_encrypt(int flen, const unsigned char *from,
unsigned char *to, RSA *rsa, int padding)
{
BIGNUM *f, *ret;
int i, j, k, num = 0, r = -1;
int i, num = 0, r = -1;
unsigned char *buf = NULL;
BN_CTX *ctx = NULL;
@ -142,15 +142,10 @@ static int rsa_ossl_public_encrypt(int flen, const unsigned char *from,
goto err;
/*
* put in leading 0 bytes if the number is less than the length of the
* modulus
* BN_bn2binpad puts in leading 0 bytes if the number is less than
* the length of the modulus.
*/
j = BN_num_bytes(ret);
i = BN_bn2bin(ret, &(to[num - j]));
for (k = 0; k < (num - i); k++)
to[k] = 0;
r = num;
r = BN_bn2binpad(ret, to, num);
err:
if (ctx != NULL)
BN_CTX_end(ctx);
@ -239,7 +234,7 @@ static int rsa_ossl_private_encrypt(int flen, const unsigned char *from,
unsigned char *to, RSA *rsa, int padding)
{
BIGNUM *f, *ret, *res;
int i, j, k, num = 0, r = -1;
int i, num = 0, r = -1;
unsigned char *buf = NULL;
BN_CTX *ctx = NULL;
int local_blinding = 0;
@ -354,15 +349,10 @@ static int rsa_ossl_private_encrypt(int flen, const unsigned char *from,
}
/*
* put in leading 0 bytes if the number is less than the length of the
* modulus
* BN_bn2binpad puts in leading 0 bytes if the number is less than
* the length of the modulus.
*/
j = BN_num_bytes(res);
i = BN_bn2bin(res, &(to[num - j]));
for (k = 0; k < (num - i); k++)
to[k] = 0;
r = num;
r = BN_bn2binpad(res, to, num);
err:
if (ctx != NULL)
BN_CTX_end(ctx);
@ -376,7 +366,6 @@ static int rsa_ossl_private_decrypt(int flen, const unsigned char *from,
{
BIGNUM *f, *ret;
int j, num = 0, r = -1;
unsigned char *p;
unsigned char *buf = NULL;
BN_CTX *ctx = NULL;
int local_blinding = 0;
@ -472,8 +461,7 @@ static int rsa_ossl_private_decrypt(int flen, const unsigned char *from,
if (!rsa_blinding_invert(blinding, ret, unblind, ctx))
goto err;
p = buf;
j = BN_bn2bin(ret, p); /* j is only used with no-padding mode */
j = BN_bn2binpad(ret, buf, num);
switch (padding) {
case RSA_PKCS1_PADDING:
@ -486,7 +474,7 @@ static int rsa_ossl_private_decrypt(int flen, const unsigned char *from,
r = RSA_padding_check_SSLv23(to, num, buf, j, num);
break;
case RSA_NO_PADDING:
r = RSA_padding_check_none(to, num, buf, j, num);
memcpy(to, buf, (r = j));
break;
default:
RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
@ -509,7 +497,6 @@ static int rsa_ossl_public_decrypt(int flen, const unsigned char *from,
{
BIGNUM *f, *ret;
int i, num = 0, r = -1;
unsigned char *p;
unsigned char *buf = NULL;
BN_CTX *ctx = NULL;
@ -574,8 +561,7 @@ static int rsa_ossl_public_decrypt(int flen, const unsigned char *from,
if (!BN_sub(ret, rsa->n, ret))
goto err;
p = buf;
i = BN_bn2bin(ret, p);
i = BN_bn2binpad(ret, buf, num);
switch (padding) {
case RSA_PKCS1_PADDING:
@ -585,7 +571,7 @@ static int rsa_ossl_public_decrypt(int flen, const unsigned char *from,
r = RSA_padding_check_X931(to, num, buf, i, num);
break;
case RSA_NO_PADDING:
r = RSA_padding_check_none(to, num, buf, i, num);
memcpy(to, buf, (r = i));
break;
default:
RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_UNKNOWN_PADDING_TYPE);

39
crypto/rsa/rsa_pk1.c
View File

@ -175,27 +175,30 @@ int RSA_padding_check_PKCS1_type_2(unsigned char *to, int tlen,
if (num < 11)
goto err;
em = OPENSSL_zalloc(num);
if (em == NULL) {
RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_2, ERR_R_MALLOC_FAILURE);
return -1;
if (flen != num) {
em = OPENSSL_zalloc(num);
if (em == NULL) {
RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_2, ERR_R_MALLOC_FAILURE);
return -1;
}
/*
* Caller is encouraged to pass zero-padded message created with
* BN_bn2binpad, but if it doesn't, we do this zero-padding copy
* to avoid leaking that information. The copy still leaks some
* side-channel information, but it's impossible to have a fixed
* memory access pattern since we can't read out of the bounds of
* |from|.
*/
memcpy(em + num - flen, from, flen);
from = em;
}
/*
* Always do this zero-padding copy (even when num == flen) to avoid
* leaking that information. The copy still leaks some side-channel
* information, but it's impossible to have a fixed memory access
* pattern since we can't read out of the bounds of |from|.
*
* TODO(emilia): Consider porting BN_bn2bin_padded from BoringSSL.
*/
memcpy(em + num - flen, from, flen);
good = constant_time_is_zero(em[0]);
good &= constant_time_eq(em[1], 2);
good = constant_time_is_zero(from[0]);
good &= constant_time_eq(from[1], 2);
found_zero_byte = 0;
for (i = 2; i < num; i++) {
unsigned int equals0 = constant_time_is_zero(em[i]);
unsigned int equals0 = constant_time_is_zero(from[i]);
zero_index =
constant_time_select_int(~found_zero_byte & equals0, i,
zero_index);
@ -203,7 +206,7 @@ int RSA_padding_check_PKCS1_type_2(unsigned char *to, int tlen,
}
/*
* PS must be at least 8 bytes long, and it starts two bytes into |em|.
* PS must be at least 8 bytes long, and it starts two bytes into |from|.
* If we never found a 0-byte, then |zero_index| is 0 and the check
* also fails.
*/
@ -232,7 +235,7 @@ int RSA_padding_check_PKCS1_type_2(unsigned char *to, int tlen,
goto err;
}
memcpy(to, em + msg_index, mlen);
memcpy(to, from + msg_index, mlen);
err:
OPENSSL_clear_free(em, num);

8
crypto/rsa/rsa_ssl.c
View File

@ -63,6 +63,14 @@ int RSA_padding_check_SSLv23(unsigned char *to, int tlen,
RSAerr(RSA_F_RSA_PADDING_CHECK_SSLV23, RSA_R_DATA_TOO_SMALL);
return -1;
}
/* Accept even zero-padded input */
if (flen == num) {
if (*(p++) != 0) {
RSAerr(RSA_F_RSA_PADDING_CHECK_SSLV23, RSA_R_BLOCK_TYPE_IS_NOT_02);
return -1;
}
flen--;
}
if ((num != (flen + 1)) || (*(p++) != 02)) {
RSAerr(RSA_F_RSA_PADDING_CHECK_SSLV23, RSA_R_BLOCK_TYPE_IS_NOT_02);
return -1;