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RT3067: simplify patch

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(Original commit adb46dbc6d)

Use the new constant-time methods consistently in s3_srvr.c

Reviewed-by: Kurt Roeckx <kurt@openssl.org>
(cherry picked from commit 455b65dfab)

Conflicts:
	ssl/Makefile
This commit is contained in:
Emilia Kasper 2014-09-04 13:04:42 +02:00
parent c36ceb0b15
commit 9a6940a349
4 changed files with 94 additions and 72 deletions
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15
crypto/constant_time_locl.h
View file

@ -106,6 +106,11 @@ static inline unsigned char constant_time_is_zero_8(unsigned int a);
static inline unsigned int constant_time_eq(unsigned int a, unsigned int b);
/* Convenience method for getting an 8-bit mask. */
static inline unsigned char constant_time_eq_8(unsigned int a, unsigned int b);
/* Signed integers. */
static inline unsigned int constant_time_eq_int(int a, int b);
/* Convenience method for getting an 8-bit mask. */
static inline unsigned char constant_time_eq_int_8(int a, int b);
/*
* Returns (mask & a) | (~mask & b).
@ -177,6 +182,16 @@ static inline unsigned char constant_time_eq_8(unsigned int a, unsigned int b)
return (unsigned char)(constant_time_eq(a, b));
}
static inline unsigned int constant_time_eq_int(int a, int b)
{
return constant_time_eq((unsigned)(a), (unsigned)(b));
}
static inline unsigned char constant_time_eq_int_8(int a, int b)
{
return constant_time_eq_8((unsigned)(a), (unsigned)(b));
}
static inline unsigned int constant_time_select(unsigned int mask,
unsigned int a, unsigned int b)
{

39
crypto/constant_time_test.c
View file

@ -196,6 +196,45 @@ static int test_select_int(int a, int b)
return 0;
}
static int test_eq_int(int a, int b)
{
unsigned int equal = constant_time_eq_int(a, b);
if (a == b && equal != CONSTTIME_TRUE)
{
fprintf(stderr, "Test failed for constant_time_select(%d, %d): "
"expected %du(TRUE), got %du\n",
a, b, CONSTTIME_TRUE, equal);
return 1;
}
else if (a != b && equal != CONSTTIME_FALSE)
{
fprintf(stderr, "Test failed for constant_time_select(%d, %d): "
"expected %du(FALSE), got %du\n",
a, b, CONSTTIME_FALSE, equal);
return 1;
}
return 0;
}
static int test_eq_int_8(int a, int b)
{
unsigned char equal = constant_time_eq_int_8(a, b);
if (a == b && equal != CONSTTIME_TRUE_8)
{
fprintf(stderr, "Test failed for constant_time_select(%d, %d): "
"expected %u(TRUE), got %u\n",
a, b, CONSTTIME_TRUE_8, equal);
return 1;
}
else if (a != b && equal != CONSTTIME_FALSE_8)
{
fprintf(stderr, "Test failed for constant_time_select(%d, %d): "
"expected %u(FALSE), got %u\n",
a, b, CONSTTIME_FALSE_8, equal);
return 1;
}
return 0;
}
static unsigned int test_values[] = {0, 1, 1024, 12345, 32000, UINT_MAX/2-1,
UINT_MAX/2, UINT_MAX/2+1, UINT_MAX-1,

44
ssl/Makefile
View file

@ -636,28 +636,28 @@ s3_pkt.o: ../include/openssl/ssl23.h ../include/openssl/ssl3.h
s3_pkt.o: ../include/openssl/stack.h ../include/openssl/symhacks.h
s3_pkt.o: ../include/openssl/tls1.h ../include/openssl/x509.h
s3_pkt.o: ../include/openssl/x509_vfy.h s3_pkt.c ssl_locl.h
s3_srvr.o: ../e_os.h ../include/openssl/asn1.h ../include/openssl/bio.h
s3_srvr.o: ../include/openssl/bn.h ../include/openssl/buffer.h
s3_srvr.o: ../include/openssl/comp.h ../include/openssl/crypto.h
s3_srvr.o: ../include/openssl/dh.h ../include/openssl/dsa.h
s3_srvr.o: ../include/openssl/dtls1.h ../include/openssl/e_os2.h
s3_srvr.o: ../include/openssl/ec.h ../include/openssl/ecdh.h
s3_srvr.o: ../include/openssl/ecdsa.h ../include/openssl/err.h
s3_srvr.o: ../include/openssl/evp.h ../include/openssl/hmac.h
s3_srvr.o: ../include/openssl/krb5_asn.h ../include/openssl/kssl.h
s3_srvr.o: ../include/openssl/lhash.h ../include/openssl/md5.h
s3_srvr.o: ../include/openssl/obj_mac.h ../include/openssl/objects.h
s3_srvr.o: ../include/openssl/opensslconf.h ../include/openssl/opensslv.h
s3_srvr.o: ../include/openssl/ossl_typ.h ../include/openssl/pem.h
s3_srvr.o: ../include/openssl/pem2.h ../include/openssl/pkcs7.h
s3_srvr.o: ../include/openssl/pqueue.h ../include/openssl/rand.h
s3_srvr.o: ../include/openssl/rsa.h ../include/openssl/safestack.h
s3_srvr.o: ../include/openssl/sha.h ../include/openssl/ssl.h
s3_srvr.o: ../include/openssl/ssl2.h ../include/openssl/ssl23.h
s3_srvr.o: ../include/openssl/ssl3.h ../include/openssl/stack.h
s3_srvr.o: ../include/openssl/symhacks.h ../include/openssl/tls1.h
s3_srvr.o: ../include/openssl/x509.h ../include/openssl/x509_vfy.h kssl_lcl.h
s3_srvr.o: s3_srvr.c ssl_locl.h
s3_srvr.o: ../crypto/constant_time_locl.h ../e_os.h ../include/openssl/asn1.h
s3_srvr.o: ../include/openssl/bio.h ../include/openssl/bn.h
s3_srvr.o: ../include/openssl/buffer.h ../include/openssl/comp.h
s3_srvr.o: ../include/openssl/crypto.h ../include/openssl/dh.h
s3_srvr.o: ../include/openssl/dsa.h ../include/openssl/dtls1.h
s3_srvr.o: ../include/openssl/e_os2.h ../include/openssl/ec.h
s3_srvr.o: ../include/openssl/ecdh.h ../include/openssl/ecdsa.h
s3_srvr.o: ../include/openssl/err.h ../include/openssl/evp.h
s3_srvr.o: ../include/openssl/hmac.h ../include/openssl/krb5_asn.h
s3_srvr.o: ../include/openssl/kssl.h ../include/openssl/lhash.h
s3_srvr.o: ../include/openssl/md5.h ../include/openssl/obj_mac.h
s3_srvr.o: ../include/openssl/objects.h ../include/openssl/opensslconf.h
s3_srvr.o: ../include/openssl/opensslv.h ../include/openssl/ossl_typ.h
s3_srvr.o: ../include/openssl/pem.h ../include/openssl/pem2.h
s3_srvr.o: ../include/openssl/pkcs7.h ../include/openssl/pqueue.h
s3_srvr.o: ../include/openssl/rand.h ../include/openssl/rsa.h
s3_srvr.o: ../include/openssl/safestack.h ../include/openssl/sha.h
s3_srvr.o: ../include/openssl/ssl.h ../include/openssl/ssl2.h
s3_srvr.o: ../include/openssl/ssl23.h ../include/openssl/ssl3.h
s3_srvr.o: ../include/openssl/stack.h ../include/openssl/symhacks.h
s3_srvr.o: ../include/openssl/tls1.h ../include/openssl/x509.h
s3_srvr.o: ../include/openssl/x509_vfy.h kssl_lcl.h s3_srvr.c ssl_locl.h
ssl_algs.o: ../e_os.h ../include/openssl/asn1.h ../include/openssl/bio.h
ssl_algs.o: ../include/openssl/buffer.h ../include/openssl/comp.h
ssl_algs.o: ../include/openssl/crypto.h ../include/openssl/dsa.h

68
ssl/s3_srvr.c
View file

@ -154,6 +154,7 @@
#include <stdio.h>
#include "ssl_locl.h"
#include "kssl_lcl.h"
#include "../crypto/constant_time_locl.h"
#include <openssl/buffer.h>
#include <openssl/rand.h>
#include <openssl/objects.h>
@ -2011,8 +2012,8 @@ int ssl3_get_client_key_exchange(SSL *s)
if (alg_k & SSL_kRSA)
{
unsigned char rand_premaster_secret[SSL_MAX_MASTER_KEY_LENGTH];
int decrypt_len, decrypt_good_mask;
unsigned char version_good;
int decrypt_len;
unsigned char decrypt_good, version_good;
/* FIX THIS UP EAY EAY EAY EAY */
if (s->s3->tmp.use_rsa_tmp)
@ -2076,18 +2077,18 @@ int ssl3_get_client_key_exchange(SSL *s)
ERR_clear_error();
/* decrypt_len should be SSL_MAX_MASTER_KEY_LENGTH.
* decrypt_good_mask will be zero if so and non-zero otherwise. */
decrypt_good_mask = decrypt_len ^ SSL_MAX_MASTER_KEY_LENGTH;
* decrypt_good will be 0xff if so and zero otherwise. */
decrypt_good = constant_time_eq_int_8(decrypt_len, SSL_MAX_MASTER_KEY_LENGTH);
/* If the version in the decrypted pre-master secret is correct
* then version_good will be zero. The Klima-Pokorny-Rosa
* extension of Bleichenbacher's attack
* then version_good will be 0xff, otherwise it'll be zero.
* The Klima-Pokorny-Rosa extension of Bleichenbacher's attack
* (http://eprint.iacr.org/2003/052/) exploits the version
* number check as a "bad version oracle". Thus version checks
* are done in constant time and are treated like any other
* decryption error. */
version_good = p[0] ^ (s->client_version>>8);
version_good |= p[1] ^ (s->client_version&0xff);
version_good = constant_time_eq_8(p[0], (unsigned)(s->client_version>>8));
version_good &= constant_time_eq_8(p[1], (unsigned)(s->client_version&0xff));
/* The premaster secret must contain the same version number as
* the ClientHello to detect version rollback attacks
@ -2098,55 +2099,22 @@ int ssl3_get_client_key_exchange(SSL *s)
* SSL_OP_TLS_ROLLBACK_BUG is set, tolerate such clients. */
if (s->options & SSL_OP_TLS_ROLLBACK_BUG)
{
unsigned char workaround_mask = version_good;
unsigned char workaround;
/* workaround_mask will be 0xff if version_good is
* non-zero (i.e. the version match failed). Otherwise
* it'll be 0x00. */
workaround_mask |= workaround_mask >> 4;
workaround_mask |= workaround_mask >> 2;
workaround_mask |= workaround_mask >> 1;
workaround_mask = ~((workaround_mask & 1) - 1);
workaround = p[0] ^ (s->version>>8);
workaround |= p[1] ^ (s->version&0xff);
/* If workaround_mask is 0xff (i.e. there was a version
* mismatch) then we copy the value of workaround over
* version_good. */
version_good = (workaround & workaround_mask) |
(version_good & ~workaround_mask);
unsigned char workaround_good;
workaround_good = constant_time_eq_8(p[0], (unsigned)(s->version>>8));
workaround_good &= constant_time_eq_8(p[1], (unsigned)(s->version&0xff));
version_good |= workaround_good;
}
/* If any bits in version_good are set then they'll poision
* decrypt_good_mask and cause rand_premaster_secret to be
* used. */
decrypt_good_mask |= version_good;
/* decrypt_good_mask will be zero iff decrypt_len ==
* SSL_MAX_MASTER_KEY_LENGTH and the version check passed. We
* fold the bottom 32 bits of it with an OR so that the LSB
* will be zero iff everything is good. This assumes that we'll
* never decrypt a value > 2**31 bytes, which seems safe. */
decrypt_good_mask |= decrypt_good_mask >> 16;
decrypt_good_mask |= decrypt_good_mask >> 8;
decrypt_good_mask |= decrypt_good_mask >> 4;
decrypt_good_mask |= decrypt_good_mask >> 2;
decrypt_good_mask |= decrypt_good_mask >> 1;
/* Now select only the LSB and subtract one. If decrypt_len ==
* SSL_MAX_MASTER_KEY_LENGTH and the version check passed then
* decrypt_good_mask will be all ones. Otherwise it'll be all
* zeros. */
decrypt_good_mask &= 1;
decrypt_good_mask--;
/* Both decryption and version must be good for decrypt_good
* to remain non-zero (0xff). */
decrypt_good &= version_good;
/* Now copy rand_premaster_secret over p using
* decrypt_good_mask. */
for (i = 0; i < (int) sizeof(rand_premaster_secret); i++)
{
p[i] = (p[i] & decrypt_good_mask) |
(rand_premaster_secret[i] & ~decrypt_good_mask);
p[i] = constant_time_select_8(decrypt_good, p[i],
rand_premaster_secret[i]);
}
s->session->master_key_length=