meta-openembedded/meta-oe/recipes-support/opensc/files/CVE-2023-5992-0001.patch

From 9c14d6d996e526ebfda75de7b577255acf7ad86d 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 01/10] Reimplement removing of PKCS#1 v1.5 padding to be time
 constant

CVE: CVE-2023-5992
Upstream-Status: Backport [https://github.com/OpenSC/OpenSC/pull/2948]

Signed-off-by: Zhang Peng <peng.zhang1.cn@windriver.com>
---
 src/common/Makefile.am      |   5 +-
 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, 209 insertions(+), 39 deletions(-)
 create mode 100644 src/common/constant-time.h

diff --git a/src/common/Makefile.am b/src/common/Makefile.am
index 83a40e1c2..c4cfff185 100644
--- a/src/common/Makefile.am
+++ b/src/common/Makefile.am
@@ -8,7 +8,7 @@ dist_noinst_DATA = \
 	LICENSE.compat_getopt compat_getopt.txt \
 	compat_getopt_main.c \
 	README.compat_strlcpy compat_strlcpy.3
-noinst_HEADERS = compat_strlcat.h compat_strlcpy.h compat_strnlen.h compat_getpass.h compat_getopt.h simclist.h libpkcs11.h libscdl.h
+noinst_HEADERS = compat_strlcat.h compat_strlcpy.h compat_strnlen.h compat_getpass.h compat_getopt.h simclist.h libpkcs11.h libscdl.h constant-time.h
 
 AM_CPPFLAGS = -I$(top_srcdir)/src
 
@@ -40,7 +40,8 @@ TIDY_FILES = \
 	compat_report_rangecheckfailure.c \
 	compat___iob_func.c \
 	simclist.c simclist.h \
-	libpkcs11.c libscdl.c
+	libpkcs11.c libscdl.c \
+	constant-time.h
 
 check-local:
 	if [ -x "$(CLANGTIDY)" ]; then clang-tidy -config='' --checks='$(TIDY_CHECKS)' -header-filter=.* $(addprefix $(srcdir)/,$(TIDY_FILES)) -- $(TIDY_FLAGS); fi
diff --git a/src/common/constant-time.h b/src/common/constant-time.h
new file mode 100644
index 000000000..40c3e500c
--- /dev/null
+++ b/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 */
diff --git a/src/libopensc/internal.h b/src/libopensc/internal.h
index e7ac63ccf..57568d311 100644
--- a/src/libopensc/internal.h
+++ b/src/libopensc/internal.h
@@ -166,8 +166,8 @@ int _sc_card_add_xeddsa_alg(struct sc_card *card, unsigned int key_length,
 
 int sc_pkcs1_strip_01_padding(struct sc_context *ctx, const u8 *in_dat, size_t in_len,
 		u8 *out_dat, size_t *out_len);
-int sc_pkcs1_strip_02_padding(struct sc_context *ctx, const u8 *data, size_t len,
-		u8 *out_dat, size_t *out_len);
+int sc_pkcs1_strip_02_padding_constant_time(sc_context_t *ctx, unsigned int n, const u8 *data,
+		unsigned int data_len, u8 *out, unsigned int *out_len);
 int sc_pkcs1_strip_digest_info_prefix(unsigned int *algorithm,
 		const u8 *in_dat, size_t in_len, u8 *out_dat, size_t *out_len);
 
diff --git a/src/libopensc/padding.c b/src/libopensc/padding.c
index e4940ea2b..3a8b81c3f 100644
--- a/src/libopensc/padding.c
+++ b/src/libopensc/padding.c
@@ -32,10 +32,13 @@
 #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
  */
@@ -143,45 +146,82 @@ sc_pkcs1_strip_01_padding(struct sc_context *ctx, const u8 *in_dat, size_t in_le
 	return SC_SUCCESS;
 }
 
-
-/* remove pkcs1 BT02 padding (adding BT02 padding is currently not
- * needed/implemented) */
+/* Remove pkcs1 BT02 padding (adding BT02 padding is currently not
+ * needed/implemented) in constant-time.
+ * Original source: https://github.com/openssl/openssl/blob/9890cc42daff5e2d0cad01ac4bf78c391f599a6e/crypto/rsa/rsa_pk1.c#L171 */
 int
-sc_pkcs1_strip_02_padding(sc_context_t *ctx, const u8 *data, size_t len, u8 *out, size_t *out_len)
+sc_pkcs1_strip_02_padding_constant_time(sc_context_t *ctx, unsigned int n, const u8 *data, unsigned int data_len, u8 *out, unsigned int *out_len)
 {
-	unsigned int	n = 0;
-
+	unsigned int i = 0;
+	u8 *msg, *msg_orig = NULL;
+	unsigned int good, found_zero_byte, mask;
+	unsigned int zero_index = 0, msg_index, mlen = -1, len = 0;
 	LOG_FUNC_CALLED(ctx);
-	if (data == NULL || len < 3)
+
+	if (data == NULL || data_len <= 0 || data_len > n || n < SC_PKCS1_PADDING_MIN_SIZE)
 		LOG_FUNC_RETURN(ctx, SC_ERROR_INTERNAL);
 
-	/* skip leading zero byte */
-	if (*data == 0) {
-		data++;
-		len--;
+	msg = msg_orig = calloc(n, sizeof(u8));
+	if (msg == NULL)
+		LOG_FUNC_RETURN(ctx, SC_ERROR_INTERNAL);
+
+	/*
+	 * We can not check length of input data straight away and still we need to read
+	 * from input even when the input is not as long as needed to keep the time constant.
+	 * If data has wrong size, it is padded by zeroes from left and the following checks
+	 * do not pass.
+	 */
+	len = data_len;
+	for (data += len, msg += n, i = 0; i < n; i++) {
+		mask = ~constant_time_is_zero(len);
+		len -= 1 & mask;
+		data -= 1 & mask;
+		*--msg = *data & mask;
+	}
+	// check first byte to be 0x00
+	good = constant_time_is_zero(msg[0]);
+	// check second byte to be 0x02
+	good &= constant_time_eq(msg[1], 2);
+
+	// find zero byte after random data in padding
+	found_zero_byte = 0;
+	for (i = 2; i < n; i++) {
+		unsigned int equals0 = constant_time_is_zero(msg[i]);
+		zero_index = constant_time_select(~found_zero_byte & equals0, i, zero_index);
+		found_zero_byte |= equals0;
 	}
-	if (data[0] != 0x02)
-		LOG_FUNC_RETURN(ctx, SC_ERROR_WRONG_PADDING);
-	/* skip over padding bytes */
-	for (n = 1; n < len && data[n]; n++)
-		;
-	/* Must be at least 8 pad bytes */
-	if (n >= len || n < 9)
-		LOG_FUNC_RETURN(ctx, SC_ERROR_WRONG_PADDING);
-	n++;
-	if (out == NULL)
-		/* just check the padding */
-		LOG_FUNC_RETURN(ctx, SC_SUCCESS);
 
-	/* Now move decrypted contents to head of buffer */
-	if (*out_len < len - n)
-		LOG_FUNC_RETURN(ctx, SC_ERROR_INTERNAL);
-	*out_len = len - n;
-	memmove(out, data + n, *out_len);
+	// zero_index stands for index of last found zero
+	good &= constant_time_ge(zero_index, 2 + 8);
+
+	// start of the actual message in data
+	msg_index = zero_index + 1;
+
+	// length of message
+	mlen = data_len - msg_index;
+
+	// check that message fits into out buffer
+	good &= constant_time_ge(*out_len, mlen);
+
+	// move the result in-place by |num|-SC_PKCS1_PADDING_MIN_SIZE-|mlen| bytes to the left.
+	*out_len = constant_time_select(constant_time_lt(n - SC_PKCS1_PADDING_MIN_SIZE, *out_len),
+			n - SC_PKCS1_PADDING_MIN_SIZE, *out_len);
+	for (msg_index = 1; msg_index < n - SC_PKCS1_PADDING_MIN_SIZE; msg_index <<= 1) {
+		mask = ~constant_time_eq(msg_index & (n - SC_PKCS1_PADDING_MIN_SIZE - mlen), 0);
+		for (i = SC_PKCS1_PADDING_MIN_SIZE; i < n - msg_index; i++)
+			msg[i] = constant_time_select_8(mask, msg[i + msg_index], msg[i]);
+	}
+	// move message into out buffer, if good
+	for (i = 0; i < *out_len; i++) {
+		unsigned int msg_index;
+		// when out is longer than message in data, use some bogus index in msg
+		mask = good & constant_time_lt(i, mlen);
+		msg_index = constant_time_select(mask, i + SC_PKCS1_PADDING_MIN_SIZE, 0); // to now overflow msg buffer
+		out[i] = constant_time_select_8(mask, msg[msg_index], out[i]);
+	}
 
-	sc_log(ctx, "stripped output(%"SC_FORMAT_LEN_SIZE_T"u): %s", len - n,
-	       sc_dump_hex(out, len - n));
-	LOG_FUNC_RETURN(ctx, len - n);
+	free(msg_orig);
+	return constant_time_select(good, mlen, SC_ERROR_WRONG_PADDING);
 }
 
 /* add/remove DigestInfo prefix */
diff --git a/src/libopensc/pkcs15-sec.c b/src/libopensc/pkcs15-sec.c
index b86cb77c3..cea46798a 100644
--- a/src/libopensc/pkcs15-sec.c
+++ b/src/libopensc/pkcs15-sec.c
@@ -308,8 +308,9 @@ int sc_pkcs15_decipher(struct sc_pkcs15_card *p15card,
 
 	/* Strip any padding */
 	if (pad_flags & SC_ALGORITHM_RSA_PAD_PKCS1) {
-		size_t s = r;
-		r = sc_pkcs1_strip_02_padding(ctx, out, s, out, &s);
+		int s = r;
+		int key_size = alg_info->key_length;
+		r = sc_pkcs1_strip_02_padding_constant_time(ctx, key_size / 8, out, s, out, &s);
 		LOG_TEST_RET(ctx, r, "Invalid PKCS#1 padding");
 	}
 
diff --git a/src/minidriver/minidriver.c b/src/minidriver/minidriver.c
index 0c089feab..e4d693a09 100644
--- a/src/minidriver/minidriver.c
+++ b/src/minidriver/minidriver.c
@@ -4582,9 +4582,9 @@ DWORD WINAPI CardRSADecrypt(__in PCARD_DATA pCardData,
 					  "sc_pkcs15_decipher: DECRYPT-INFO dwVersion=%lu\n",
 					  (unsigned long)pInfo->dwVersion);
 				if (pInfo->dwPaddingType == CARD_PADDING_PKCS1)   {
-					size_t temp = pInfo->cbData;
+					unsigned int temp = pInfo->cbData;
 					logprintf(pCardData, 2, "sc_pkcs15_decipher: stripping PKCS1 padding\n");
-					r = sc_pkcs1_strip_02_padding(vs->ctx, pbuf2, pInfo->cbData, pbuf2, &temp);
+					r = sc_pkcs1_strip_02_padding_constant_time(vs->ctx, prkey_info->modulus_length / 8, pbuf2, pInfo->cbData, pbuf2, &temp);
 					pInfo->cbData = (DWORD) temp;
 					if (r < 0)   {
 						logprintf(pCardData, 2, "Cannot strip PKCS1 padding: %i\n", r);
-- 
2.50.0