File opensc-CVE-2023-5992.patch of Package opensc.35665
From b9e1d344df1f850a9b15bce6294f72c1620d0b45 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Veronika=20Hanul=C3=ADkov=C3=A1?= <vhanulik@redhat.com>
Date: Mon, 13 Nov 2023 13:54:54 +0100
Subject: [PATCH 1/8] Reimplement removing of PKCS#1 v1.5 padding to be time
constant
---
src/common/Makefile.am | 6 +-
src/common/constant-time.h | 128 ++++++++++++++++++++++++++++++++++++
src/libopensc/internal.h | 4 +-
src/libopensc/padding.c | 102 +++++++++++++++++++---------
src/libopensc/pkcs15-sec.c | 5 +-
src/minidriver/minidriver.c | 4 +-
6 files changed, 210 insertions(+), 39 deletions(-)
create mode 100644 src/common/constant-time.h
Index: opensc-0.13.0/src/common/constant-time.h
===================================================================
--- /dev/null
+++ opensc-0.13.0/src/common/constant-time.h
@@ -0,0 +1,128 @@
+/* Original source: https://github.com/openssl/openssl/blob/9890cc42daff5e2d0cad01ac4bf78c391f599a6e/include/internal/constant_time.h */
+
+#ifndef CONSTANT_TIME_H
+#define CONSTANT_TIME_H
+
+#include <stdlib.h>
+#include <string.h>
+
+#if !defined(inline)
+#if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L
+#define constant_inline inline
+#elif defined(__GNUC__) && __GNUC__ >= 2
+#elif defined(__GNUC__) && __GNUC__ >= 2
+#elif defined(_MSC_VER)
+#define constant_inline __inline
+#else
+#define constant_inline
+#endif
+#else /* use what caller wants as inline may be from config.h */
+#define constant_inline inline /* inline */
+#endif
+
+/*-
+ * The boolean methods return a bitmask of all ones (0xff...f) for true
+ * and 0 for false. For example,
+ * if (a < b) {
+ * c = a;
+ * } else {
+ * c = b;
+ * }
+ * can be written as
+ * unsigned int lt = constant_time_lt(a, b);
+ * c = constant_time_select(lt, a, b);
+ */
+
+static constant_inline unsigned int
+value_barrier(unsigned int a)
+{
+ volatile unsigned int r = a;
+ return r;
+}
+
+static constant_inline size_t
+value_barrier_s(size_t a)
+{
+ volatile size_t r = a;
+ return r;
+}
+
+/* MSB */
+static constant_inline size_t
+constant_time_msb_s(size_t a)
+{
+ return 0 - (a >> (sizeof(a) * 8 - 1));
+}
+
+static constant_inline unsigned int
+constant_time_msb(unsigned int a)
+{
+ return 0 - (a >> (sizeof(a) * 8 - 1));
+}
+
+/* Select */
+static constant_inline unsigned int
+constant_time_select(unsigned int mask, unsigned int a, unsigned int b)
+{
+ return (value_barrier(mask) & a) | (value_barrier(~mask) & b);
+}
+
+static constant_inline unsigned char
+constant_time_select_8(unsigned char mask, unsigned char a, unsigned char b)
+{
+ return (unsigned char)constant_time_select(mask, a, b);
+}
+
+static constant_inline size_t
+constant_time_select_s(size_t mask, size_t a, size_t b)
+{
+ return (value_barrier_s(mask) & a) | (value_barrier_s(~mask) & b);
+}
+
+/* Zero */
+static constant_inline unsigned int
+constant_time_is_zero(unsigned int a)
+{
+ return constant_time_msb(~a & (a - 1));
+}
+
+static constant_inline size_t
+constant_time_is_zero_s(size_t a)
+{
+ return constant_time_msb_s(~a & (a - 1));
+}
+
+/* Comparison*/
+static constant_inline size_t
+constant_time_lt_s(size_t a, size_t b)
+{
+ return constant_time_msb_s(a ^ ((a ^ b) | ((a - b) ^ b)));
+}
+
+static constant_inline unsigned int
+constant_time_lt(unsigned int a, unsigned int b)
+{
+ return constant_time_msb(a ^ ((a ^ b) | ((a - b) ^ b)));
+}
+
+static constant_inline unsigned int
+constant_time_ge(unsigned int a, unsigned int b)
+{
+ return ~constant_time_lt(a, b);
+}
+
+/* Equality*/
+
+static constant_inline unsigned int
+constant_time_eq(unsigned int a, unsigned int b)
+{
+ return constant_time_is_zero(a ^ b);
+}
+
+static constant_inline size_t
+constant_time_eq_s(size_t a, size_t b)
+{
+ return constant_time_is_zero_s(a ^ b);
+}
+
+#endif /* CONSTANT_TIME_H */
Index: opensc-0.13.0/src/libopensc/padding.c
===================================================================
--- opensc-0.13.0.orig/src/libopensc/padding.c
+++ opensc-0.13.0/src/libopensc/padding.c
@@ -24,10 +24,13 @@
#include <string.h>
#include <stdlib.h>
+#include "common/constant-time.h"
#include "internal.h"
/* TODO doxygen comments */
+#define SC_PKCS1_PADDING_MIN_SIZE 11
+
/*
* Prefixes for pkcs-v1 signatures
*/
Index: opensc-0.13.0/src/tests/unittests/strip_pkcs1_2_padding.c
===================================================================
--- /dev/null
+++ opensc-0.13.0/src/tests/unittests/strip_pkcs1_2_padding.c
@@ -0,0 +1,204 @@
+#include "common/compat_strlcpy.c"
+#include "libopensc/log.c"
+#include "libopensc/padding.c"
+#include "torture.h"
+#include <cmocka.h>
+
+static void
+torture_long_output_buffer(void **state)
+{
+ unsigned int n = 14;
+ unsigned int in_len = 14;
+ unsigned char in[] = {0x00, 0x02,
+ 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
+ 0x00,
+ 'm', 's', 'g'};
+ unsigned int out_len = 3;
+ unsigned char *out = malloc(out_len * sizeof(unsigned char));
+ unsigned char result_msg[] = {'m', 's', 'g'};
+ int r = sc_pkcs1_strip_02_padding_constant_time(NULL, n, in, in_len, out, &out_len);
+ assert_int_equal(r, 3);
+ assert_memory_equal(out, result_msg, r);
+ free(out);
+}
+
+static void
+torture_short_output_buffer(void **state)
+{
+ unsigned int n = 14;
+ unsigned int in_len = 14;
+ unsigned char in[] = {0x00, 0x02,
+ 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
+ 0x00,
+ 'm', 's', 'g'};
+ unsigned int out_len = 1;
+ unsigned char *out = malloc(out_len * sizeof(unsigned char));
+ int r = sc_pkcs1_strip_02_padding_constant_time(NULL, n, in, in_len, out, &out_len);
+ assert_int_equal(r, SC_ERROR_WRONG_PADDING);
+ free(out);
+}
+
+static void
+torture_short_message_correct_padding(void **state)
+{
+ unsigned int n = 14;
+ unsigned int in_len = 14;
+ unsigned char in[] = {0x00, 0x02,
+ 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
+ 0x00,
+ 'm', 's', 'g'};
+ unsigned int out_len = 3;
+ unsigned char *out = malloc(out_len * sizeof(unsigned char));
+ unsigned char result_msg[] = {'m', 's', 'g'};
+ int r = sc_pkcs1_strip_02_padding_constant_time(NULL, n, in, in_len, out, &out_len);
+ assert_int_equal(r, 3);
+ assert_memory_equal(out, result_msg, r);
+ free(out);
+}
+
+static void
+torture_missing_first_zero(void **state)
+{
+ unsigned int n = 13;
+ unsigned int in_len = 13;
+ unsigned char in[] = {0x02,
+ 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
+ 0x00,
+ 'm', 's', 'g'};
+ unsigned int out_len = 10;
+ unsigned char *out = malloc(out_len * sizeof(unsigned char));
+ int r = sc_pkcs1_strip_02_padding_constant_time(NULL, n, in, in_len, out, &out_len);
+ assert_int_equal(r, SC_ERROR_WRONG_PADDING);
+ free(out);
+}
+
+static void
+torture_missing_two(void **state)
+{
+ unsigned int n = 13;
+ unsigned int in_len = 13;
+ unsigned char in[] = {0x00,
+ 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
+ 0x00,
+ 'm', 's', 'g'};
+ unsigned int out_len = 10;
+ unsigned char *out = malloc(out_len * sizeof(unsigned char));
+ int r = sc_pkcs1_strip_02_padding_constant_time(NULL, n, in, in_len, out, &out_len);
+ assert_int_equal(r, SC_ERROR_WRONG_PADDING);
+ free(out);
+}
+
+static void
+torture_short_padding(void **state)
+{
+ unsigned int n = 13;
+ unsigned int in_len = 13;
+ unsigned char in[] = {0x00, 0x02,
+ 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+ 0x00,
+ 'm', 's', 'g'};
+ unsigned int out_len = 10;
+ unsigned char *out = malloc(out_len * sizeof(unsigned char));
+ int r = sc_pkcs1_strip_02_padding_constant_time(NULL, n, in, in_len, out, &out_len);
+ assert_int_equal(r, SC_ERROR_WRONG_PADDING);
+ free(out);
+}
+
+static void
+torture_missing_second_zero(void **state)
+{
+ unsigned int n = 13;
+ unsigned int in_len = 13;
+ unsigned char in[] = {0x00, 0x02,
+ 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
+ 'm', 's', 'g'};
+ unsigned int out_len = 10;
+ unsigned char *out = malloc(out_len * sizeof(unsigned char));
+ int r = sc_pkcs1_strip_02_padding_constant_time(NULL, n, in, in_len, out, &out_len);
+ assert_int_equal(r, SC_ERROR_WRONG_PADDING);
+ free(out);
+}
+
+static void
+torture_missing_message(void **state)
+{
+ unsigned int n = 20;
+ unsigned int in_len = 11;
+ unsigned char in[] = {0x00, 0x02,
+ 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
+ 0x00};
+ unsigned int out_len = 11;
+ unsigned char *out = malloc(out_len * sizeof(unsigned char));
+ int r = sc_pkcs1_strip_02_padding_constant_time(NULL, n, in, in_len, out, &out_len);
+ assert_int_equal(r, SC_ERROR_WRONG_PADDING);
+ free(out);
+}
+
+static void
+torture_one_byte_message(void **state)
+{
+ unsigned int n = 12;
+ unsigned int in_len = 12;
+ unsigned char in[] = {0x00, 0x02,
+ 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
+ 0x00,
+ 'm'};
+ unsigned int out_len = 1;
+ unsigned char *out = malloc(out_len * sizeof(unsigned char));
+ unsigned char result_msg[] = {'m'};
+ int r = sc_pkcs1_strip_02_padding_constant_time(NULL, n, in, in_len, out, &out_len);
+ assert_int_equal(r, 1);
+ assert_memory_equal(out, result_msg, r);
+ free(out);
+}
+
+static void
+torture_longer_padding(void **state)
+{
+ unsigned int n = 26;
+ unsigned int in_len = 26;
+ unsigned char in[] = {0x00, 0x02,
+ 0x0e, 0x38, 0x97, 0x18, 0x16, 0x57, 0x9e, 0x30, 0xb6, 0xa5, 0x78, 0x13, 0x20, 0xca, 0x11,
+ 0x00,
+ 0x9d, 0x98, 0x3d, 0xca, 0xa9, 0xa7, 0x11, 0x0a};
+ unsigned int out_len = 8;
+ unsigned char *out = malloc(out_len * sizeof(unsigned char));
+ unsigned char result_msg[] = {0x9d, 0x98, 0x3d, 0xca, 0xa9, 0xa7, 0x11, 0x0a};
+ int r = sc_pkcs1_strip_02_padding_constant_time(NULL, n, in, in_len, out, &out_len);
+ assert_int_equal(r, 8);
+ assert_memory_equal(out, result_msg, r);
+ free(out);
+}
+
+static void
+torture_empty_message(void **state)
+{
+ unsigned int n = 18;
+ unsigned int in_len = 18;
+ unsigned char in[] = {0x00, 0x02,
+ 0x0e, 0x38, 0x97, 0x18, 0x16, 0x57, 0x9e, 0x30, 0xb6, 0xa5, 0x78, 0x13, 0x20, 0xca, 0x11,
+ 0x00};
+ unsigned int out_len = 8;
+ unsigned char *out = malloc(out_len * sizeof(unsigned char));
+ int r = sc_pkcs1_strip_02_padding_constant_time(NULL, n, in, in_len, out, &out_len);
+ assert_int_equal(r, 0);
+ free(out);
+}
+
+int
+main(void)
+{
+ const struct CMUnitTest tests[] = {
+ cmocka_unit_test(torture_long_output_buffer),
+ cmocka_unit_test(torture_short_output_buffer),
+ cmocka_unit_test(torture_short_message_correct_padding),
+ cmocka_unit_test(torture_missing_first_zero),
+ cmocka_unit_test(torture_missing_two),
+ cmocka_unit_test(torture_short_padding),
+ cmocka_unit_test(torture_missing_second_zero),
+ cmocka_unit_test(torture_missing_message),
+ cmocka_unit_test(torture_one_byte_message),
+ cmocka_unit_test(torture_longer_padding),
+ cmocka_unit_test(torture_empty_message)};
+ return cmocka_run_group_tests(tests, NULL, NULL);
+}
Index: opensc-0.13.0/src/pkcs11/framework-pkcs15.c
===================================================================
--- opensc-0.13.0.orig/src/pkcs11/framework-pkcs15.c
+++ opensc-0.13.0/src/pkcs11/framework-pkcs15.c
@@ -18,6 +18,7 @@
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
+#include "common/constant-time.h"
#include "config.h"
#include "libopensc/log.h"
#include "libopensc/asn1.h"
@@ -3449,6 +3450,7 @@ pkcs15_prkey_decrypt(struct sc_pkcs11_se
struct pkcs15_prkey_object *prkey;
unsigned char decrypted[256]; /* FIXME: Will not work for keys above 2048 bits */
int buff_too_small, rv, flags = 0, prkey_has_path = 0;
+ CK_ULONG mask, good, rv_pkcs11;
sc_log(context, "Initiating decryption.");
@@ -3485,27 +3487,53 @@ pkcs15_prkey_decrypt(struct sc_pkcs11_se
rv = sc_pkcs15_decipher(fw_data->p15_card, prkey->prv_p15obj, flags,
pEncryptedData, ulEncryptedDataLen, decrypted, sizeof(decrypted));
- if (rv < 0 && !sc_pkcs11_conf.lock_login && !prkey_has_path)
+ /* skip for PKCS#1 v1.5 padding prevent side channel attack */
+ if (!(flags & SC_ALGORITHM_RSA_PAD_PKCS1) &&
+ rv < 0 && !sc_pkcs11_conf.lock_login && !prkey_has_path)
if (reselect_app_df(fw_data->p15_card) == SC_SUCCESS)
rv = sc_pkcs15_decipher(fw_data->p15_card, prkey->prv_p15obj, flags,
pEncryptedData, ulEncryptedDataLen, decrypted, sizeof(decrypted));
sc_unlock(p11card->card);
- sc_log(context, "Decryption complete. Result %d.", rv);
+ sc_log(context, "Decryption complete.");
- if (rv < 0)
- return sc_to_cryptoki_error(rv, "C_Decrypt");
+ /* Handle following code in constant-time
+ * to prevent Marvin attack for PKCS#1 v1.5 padding. */
- buff_too_small = (*pulDataLen < (CK_ULONG)rv);
- *pulDataLen = rv;
- if (pData == NULL_PTR)
- return CKR_OK;
- if (buff_too_small)
- return CKR_BUFFER_TOO_SMALL;
- memcpy(pData, decrypted, *pulDataLen);
+ /* only padding error must be handled in constant-time way,
+ * other error can be returned straight away */
+ if ((~constant_time_eq_s(rv, SC_ERROR_WRONG_PADDING) & constant_time_lt_s(sizeof(decrypted), rv)))
+ return sc_to_cryptoki_error(rv, "C_Decrypt");
- return CKR_OK;
+ /* check rv for padding error */
+ good = ~constant_time_eq_s(rv, SC_ERROR_WRONG_PADDING);
+ rv_pkcs11 = sc_to_cryptoki_error(SC_ERROR_WRONG_PADDING, "C_Decrypt");
+ rv_pkcs11 = constant_time_select_s(good, CKR_OK, rv_pkcs11);
+
+ if (pData == NULL_PTR) {
+ /* set length only if no error */
+ *pulDataLen = constant_time_select_s(good, rv, *pulDataLen);
+ /* return error only if original rv < 0 */
+ return rv_pkcs11;
+ }
+
+ /* check whether *pulDataLen < rv and set return value for small output buffer */
+ mask = good & constant_time_lt_s(*pulDataLen, rv);
+ rv_pkcs11 = constant_time_select_s(mask, CKR_BUFFER_TOO_SMALL, rv_pkcs11);
+ good &= ~mask;
+
+ /* move everything from decrypted into out buffer constant-time, if rv is ok */
+ for (CK_ULONG i = 0; i < *pulDataLen; i++) { /* iterate over whole pData to not disclose real depadded length */
+ CK_ULONG msg_index;
+ mask = good & constant_time_lt_s(i, sizeof(decrypted)); /* i should be in the bounds of decrypted */
+ mask &= constant_time_lt_s(i, constant_time_select_s(good, rv, 0)); /* check that is in bounds of depadded message */
+ msg_index = constant_time_select_s(mask, i, 0);
+ pData[i] = constant_time_select_8(mask, decrypted[msg_index], pData[i]);
+ }
+ *pulDataLen = constant_time_select_s(good, rv, *pulDataLen);
+ /* do not log error code to prevent side channel attack */
+ return rv_pkcs11;
}
Index: opensc-0.13.0/src/pkcs11/mechanism.c
===================================================================
--- opensc-0.13.0.orig/src/pkcs11/mechanism.c
+++ opensc-0.13.0/src/pkcs11/mechanism.c
@@ -9,6 +9,7 @@
#include <stdlib.h>
#include <string.h>
+#include "common/constant-time.h"
#include "sc-pkcs11.h"
/* Also used for verification data */
@@ -754,9 +755,12 @@ sc_pkcs11_decr(struct sc_pkcs11_session
rv = op->type->decrypt(op, pEncryptedData, ulEncryptedDataLen,
pData, pulDataLen);
- if (rv != CKR_BUFFER_TOO_SMALL && pData != NULL)
+ /* terminate session for any return value except CKR_BUFFER_TOO_SMALL,
+ * perform check in time side-channel free way to prevent Marvin attack */
+ if (~constant_time_eq_s(rv, CKR_OK) & ~constant_time_eq_s(rv, CKR_BUFFER_TOO_SMALL))
session_stop_operation(session, SC_PKCS11_OPERATION_DECRYPT);
+ /* do not log error code to prevent side channel attack */
return rv;
}
Index: opensc-0.13.0/src/pkcs11/pkcs11-object.c
===================================================================
--- opensc-0.13.0.orig/src/pkcs11/pkcs11-object.c
+++ opensc-0.13.0/src/pkcs11/pkcs11-object.c
@@ -923,7 +923,8 @@ CK_RV C_Decrypt(CK_SESSION_HANDLE hSessi
rv = sc_pkcs11_decr(session, pEncryptedData, ulEncryptedDataLen,
pData, pulDataLen);
- sc_log(context, "C_Decrypt() = %s", lookup_enum ( RV_T, rv ));
+ /* do not log error code to prevent side channel attack */
+ SC_LOG("C_Decrypt()");
sc_pkcs11_unlock();
return rv;
}
@@ -1281,7 +1282,8 @@ CK_RV C_VerifyUpdate(CK_SESSION_HANDLE h
if (rv == CKR_OK)
rv = sc_pkcs11_verif_update(session, pPart, ulPartLen);
- sc_log(context, "C_VerifyUpdate() = %s", lookup_enum ( RV_T, rv ));
+ /* do not log error code to prevent side channel attack */
+ SC_LOG("C_DecryptUpdate()");
sc_pkcs11_unlock();
return rv;
#endif
@@ -1305,7 +1307,8 @@ CK_RV C_VerifyFinal(CK_SESSION_HANDLE hS
if (rv == CKR_OK)
rv = sc_pkcs11_verif_final(session, pSignature, ulSignatureLen);
- sc_log(context, "C_VerifyFinal() = %s", lookup_enum ( RV_T, rv ));
+ /* do not log error code to prevent side channel attack */
+ SC_LOG("C_DecryptFinal()");
sc_pkcs11_unlock();
return rv;
#endif
Index: opensc-0.13.0/src/pkcs11/misc.c
===================================================================
--- opensc-0.13.0.orig/src/pkcs11/misc.c
+++ opensc-0.13.0/src/pkcs11/misc.c
@@ -23,6 +23,7 @@
#include <stdlib.h>
#include <string.h>
+#include "common/constant-time.h"
#include "sc-pkcs11.h"
#define DUMP_TEMPLATE_MAX 32
