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rsa: replace magic number '11' by RSA_PKCS1_PADDING_SIZE

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Suggested by Matt Hart

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/10084)
This commit is contained in:
Dr. Matthias St. Pierre 2019-10-03 14:20:52 +02:00
parent 19cfe7847c
commit f1d1903dd3
2 changed files with 21 additions and 21 deletions
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22
crypto/rsa/rsa_pk1.c
View File

@ -57,7 +57,7 @@ int RSA_padding_check_PKCS1_type_1(unsigned char *to, int tlen,
* D - data. * D - data.
*/ */
if (num < 11) if (num < RSA_PKCS1_PADDING_SIZE)
return -1; return -1;
/* Accept inputs with and without the leading 0-byte. */ /* Accept inputs with and without the leading 0-byte. */
@ -120,7 +120,7 @@ int RSA_padding_add_PKCS1_type_2(unsigned char *to, int tlen,
int i, j; int i, j;
unsigned char *p; unsigned char *p;
if (flen > (tlen - 11)) { if (flen > (tlen - RSA_PKCS1_PADDING_SIZE)) {
RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_TYPE_2, RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_TYPE_2,
RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE); RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
return 0; return 0;
@ -169,7 +169,7 @@ int RSA_padding_check_PKCS1_type_2(unsigned char *to, int tlen,
* section 7.2.2. * section 7.2.2.
*/ */
if (flen > num || num < 11) { if (flen > num || num < RSA_PKCS1_PADDING_SIZE) {
RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_2, RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_2,
RSA_R_PKCS_DECODING_ERROR); RSA_R_PKCS_DECODING_ERROR);
return -1; return -1;
@ -226,8 +226,8 @@ int RSA_padding_check_PKCS1_type_2(unsigned char *to, int tlen,
good &= constant_time_ge(tlen, mlen); good &= constant_time_ge(tlen, mlen);
/* /*
* Move the result in-place by |num|-11-|mlen| bytes to the left. * Move the result in-place by |num|-RSA_PKCS1_PADDING_SIZE-|mlen| bytes to the left.
* Then if |good| move |mlen| bytes from |em|+11 to |to|. * Then if |good| move |mlen| bytes from |em|+RSA_PKCS1_PADDING_SIZE to |to|.
* Otherwise leave |to| unchanged. * Otherwise leave |to| unchanged.
* Copy the memory back in a way that does not reveal the size of * Copy the memory back in a way that does not reveal the size of
* the data being copied via a timing side channel. This requires copying * the data being copied via a timing side channel. This requires copying
@ -235,16 +235,16 @@ int RSA_padding_check_PKCS1_type_2(unsigned char *to, int tlen,
* length. Clear bits do a non-copy with identical access pattern. * length. Clear bits do a non-copy with identical access pattern.
* The loop below has overall complexity of O(N*log(N)). * The loop below has overall complexity of O(N*log(N)).
*/ */
tlen = constant_time_select_int(constant_time_lt(num - 11, tlen), tlen = constant_time_select_int(constant_time_lt(num - RSA_PKCS1_PADDING_SIZE, tlen),
num - 11, tlen); num - RSA_PKCS1_PADDING_SIZE, tlen);
for (msg_index = 1; msg_index < num - 11; msg_index <<= 1) { for (msg_index = 1; msg_index < num - RSA_PKCS1_PADDING_SIZE; msg_index <<= 1) {
mask = ~constant_time_eq(msg_index & (num - 11 - mlen), 0); mask = ~constant_time_eq(msg_index & (num - RSA_PKCS1_PADDING_SIZE - mlen), 0);
for (i = 11; i < num - msg_index; i++) for (i = RSA_PKCS1_PADDING_SIZE; i < num - msg_index; i++)
em[i] = constant_time_select_8(mask, em[i + msg_index], em[i]); em[i] = constant_time_select_8(mask, em[i + msg_index], em[i]);
} }
for (i = 0; i < tlen; i++) { for (i = 0; i < tlen; i++) {
mask = good & constant_time_lt(i, mlen); mask = good & constant_time_lt(i, mlen);
to[i] = constant_time_select_8(mask, em[i + 11], to[i]); to[i] = constant_time_select_8(mask, em[i + RSA_PKCS1_PADDING_SIZE], to[i]);
} }
OPENSSL_clear_free(em, num); OPENSSL_clear_free(em, num);

20
crypto/rsa/rsa_ssl.c
View File

@ -20,7 +20,7 @@ int RSA_padding_add_SSLv23(unsigned char *to, int tlen,
int i, j; int i, j;
unsigned char *p; unsigned char *p;
if (flen > (tlen - 11)) { if (flen > (tlen - RSA_PKCS1_PADDING_SIZE)) {
RSAerr(RSA_F_RSA_PADDING_ADD_SSLV23, RSAerr(RSA_F_RSA_PADDING_ADD_SSLV23,
RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE); RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
return 0; return 0;
@ -70,7 +70,7 @@ int RSA_padding_check_SSLv23(unsigned char *to, int tlen,
if (tlen <= 0 || flen <= 0) if (tlen <= 0 || flen <= 0)
return -1; return -1;
if (flen > num || num < 11) { if (flen > num || num < RSA_PKCS1_PADDING_SIZE) {
RSAerr(RSA_F_RSA_PADDING_CHECK_SSLV23, RSA_R_DATA_TOO_SMALL); RSAerr(RSA_F_RSA_PADDING_CHECK_SSLV23, RSA_R_DATA_TOO_SMALL);
return -1; return -1;
} }
@ -141,8 +141,8 @@ int RSA_padding_check_SSLv23(unsigned char *to, int tlen,
err = constant_time_select_int(mask | good, err, RSA_R_DATA_TOO_LARGE); err = constant_time_select_int(mask | good, err, RSA_R_DATA_TOO_LARGE);
/* /*
* Move the result in-place by |num|-11-|mlen| bytes to the left. * Move the result in-place by |num|-RSA_PKCS1_PADDING_SIZE-|mlen| bytes to the left.
* Then if |good| move |mlen| bytes from |em|+11 to |to|. * Then if |good| move |mlen| bytes from |em|+RSA_PKCS1_PADDING_SIZE to |to|.
* Otherwise leave |to| unchanged. * Otherwise leave |to| unchanged.
* Copy the memory back in a way that does not reveal the size of * Copy the memory back in a way that does not reveal the size of
* the data being copied via a timing side channel. This requires copying * the data being copied via a timing side channel. This requires copying
@ -150,16 +150,16 @@ int RSA_padding_check_SSLv23(unsigned char *to, int tlen,
* length. Clear bits do a non-copy with identical access pattern. * length. Clear bits do a non-copy with identical access pattern.
* The loop below has overall complexity of O(N*log(N)). * The loop below has overall complexity of O(N*log(N)).
*/ */
tlen = constant_time_select_int(constant_time_lt(num - 11, tlen), tlen = constant_time_select_int(constant_time_lt(num - RSA_PKCS1_PADDING_SIZE, tlen),
num - 11, tlen); num - RSA_PKCS1_PADDING_SIZE, tlen);
for (msg_index = 1; msg_index < num - 11; msg_index <<= 1) { for (msg_index = 1; msg_index < num - RSA_PKCS1_PADDING_SIZE; msg_index <<= 1) {
mask = ~constant_time_eq(msg_index & (num - 11 - mlen), 0); mask = ~constant_time_eq(msg_index & (num - RSA_PKCS1_PADDING_SIZE - mlen), 0);
for (i = 11; i < num - msg_index; i++) for (i = RSA_PKCS1_PADDING_SIZE; i < num - msg_index; i++)
em[i] = constant_time_select_8(mask, em[i + msg_index], em[i]); em[i] = constant_time_select_8(mask, em[i + msg_index], em[i]);
} }
for (i = 0; i < tlen; i++) { for (i = 0; i < tlen; i++) {
mask = good & constant_time_lt(i, mlen); mask = good & constant_time_lt(i, mlen);
to[i] = constant_time_select_8(mask, em[i + 11], to[i]); to[i] = constant_time_select_8(mask, em[i + RSA_PKCS1_PADDING_SIZE], to[i]);
} }
OPENSSL_clear_free(em, num); OPENSSL_clear_free(em, num);