Add support for I/O of little-endian MPI

Signed-off-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>

4 files changed, 82 insertions, 13 deletions

diff --git a/lib/crypto-backend.h b/lib/crypto-backend.h
index d57b1d1135..2930f055f5 100644
--- a/lib/crypto-backend.h
+++ b/lib/crypto-backend.h
@@ -94,7 +94,9 @@ typedef enum {
 	/* raw unsigned integer format */
 	GNUTLS_MPI_FORMAT_USG = 0,
 	/* raw signed integer format - always a leading zero when positive */
-	GNUTLS_MPI_FORMAT_STD = 1
+	GNUTLS_MPI_FORMAT_STD = 1,
+	/* raw unsigned integer format, little endian format */
+	GNUTLS_MPI_FORMAT_ULE = 2
 } gnutls_bigint_format_t;
 
 /* Multi precision integer arithmetic */
diff --git a/lib/mpi.c b/lib/mpi.c
index afe1c0ea7d..5dbcfb4069 100644
--- a/lib/mpi.c
+++ b/lib/mpi.c
@@ -153,6 +153,28 @@ _gnutls_mpi_init_scan_nz(bigint_t * ret_mpi, const void *buffer, size_t nbytes)
 	return 0;
 }
 
+int
+_gnutls_mpi_init_scan_le(bigint_t * ret_mpi, const void *buffer, size_t nbytes)
+{
+	bigint_t r;
+	int ret;
+
+	ret = _gnutls_mpi_init(&r);
+	if (ret < 0)
+		return gnutls_assert_val(ret);
+
+	ret = _gnutls_mpi_scan_le(r, buffer, nbytes);
+	if (ret < 0) {
+		gnutls_assert();
+		_gnutls_mpi_release(&r);
+		return ret;
+	}
+
+	*ret_mpi = r;
+
+	return 0;
+}
+
 /* Always has the first bit zero */
 int _gnutls_mpi_dprint_lz(const bigint_t a, gnutls_datum_t * dest)
 {
@@ -248,13 +270,18 @@ _gnutls_mpi_dprint_size(const bigint_t a, gnutls_datum_t * dest,
 	return 0;
 }
 
+/* Flags for __gnutls_x509_read_int() and __gnutls_x509_write_int */
+#define GNUTLS_X509_INT_OVERWRITE	(1 << 0)
+#define GNUTLS_X509_INT_LE		(1 << 1)
+#define GNUTLS_X509_INT_LZ		(1 << 2) /* write only */
+
 /* this function reads an integer
  * from asn1 structs. Combines the read and mpi_scan
  * steps.
  */
 static int
 __gnutls_x509_read_int(ASN1_TYPE node, const char *value,
-		      bigint_t * ret_mpi, int overwrite)
+		       bigint_t * ret_mpi, unsigned int flags)
 {
 	int result;
 	uint8_t *tmpstr = NULL;
@@ -280,9 +307,14 @@ __gnutls_x509_read_int(ASN1_TYPE node, const char *value,
 		return _gnutls_asn2err(result);
 	}
 
-	result = _gnutls_mpi_init_scan(ret_mpi, tmpstr, tmpstr_size);
+	if (flags & GNUTLS_X509_INT_LE)
+		result = _gnutls_mpi_init_scan_le(ret_mpi, tmpstr,
+						  tmpstr_size);
+	else
+		result = _gnutls_mpi_init_scan(ret_mpi, tmpstr,
+					       tmpstr_size);
 
-	if (overwrite)
+	if (flags & GNUTLS_X509_INT_OVERWRITE)
 		zeroize_key(tmpstr, tmpstr_size);
 	gnutls_free(tmpstr);
 
@@ -298,29 +330,42 @@ int
 _gnutls_x509_read_int(ASN1_TYPE node, const char *value,
 		      bigint_t * ret_mpi)
 {
-	return __gnutls_x509_read_int(node, value, ret_mpi, 0);
+	return __gnutls_x509_read_int(node, value, ret_mpi,
+				      0);
 }
 
 int
 _gnutls_x509_read_key_int(ASN1_TYPE node, const char *value,
 		      bigint_t * ret_mpi)
 {
-	return __gnutls_x509_read_int(node, value, ret_mpi, 1);
+	return __gnutls_x509_read_int(node, value, ret_mpi,
+				      GNUTLS_X509_INT_OVERWRITE);
+}
+
+int
+_gnutls_x509_read_key_int_le(ASN1_TYPE node, const char *value,
+			     bigint_t * ret_mpi)
+{
+	return __gnutls_x509_read_int(node, value, ret_mpi,
+				      GNUTLS_X509_INT_OVERWRITE |
+				      GNUTLS_X509_INT_LE);
 }
 
 /* Writes the specified integer into the specified node.
  */
 static int
 __gnutls_x509_write_int(ASN1_TYPE node, const char *value, bigint_t mpi,
-		       int lz, int overwrite)
+			unsigned int flags)
 {
 	uint8_t *tmpstr;
 	size_t s_len;
 	int result;
 
 	s_len = 0;
-	if (lz)
+	if (flags & GNUTLS_X509_INT_LZ)
 		result = _gnutls_mpi_print_lz(mpi, NULL, &s_len);
+	else if (GNUTLS_X509_INT_LE)
+		result = _gnutls_mpi_print_le(mpi, NULL, &s_len);
 	else
 		result = _gnutls_mpi_print(mpi, NULL, &s_len);
 
@@ -335,8 +380,10 @@ __gnutls_x509_write_int(ASN1_TYPE node, const char *value, bigint_t mpi,
 		return GNUTLS_E_MEMORY_ERROR;
 	}
 
-	if (lz)
+	if (flags & GNUTLS_X509_INT_LZ)
 		result = _gnutls_mpi_print_lz(mpi, tmpstr, &s_len);
+	else if (GNUTLS_X509_INT_LE)
+		result = _gnutls_mpi_print_le(mpi, tmpstr, &s_len);
 	else
 		result = _gnutls_mpi_print(mpi, tmpstr, &s_len);
 
@@ -347,8 +394,8 @@ __gnutls_x509_write_int(ASN1_TYPE node, const char *value, bigint_t mpi,
 	}
 
 	result = asn1_write_value(node, value, tmpstr, s_len);
-	
-	if (overwrite)
+
+	if (flags & GNUTLS_X509_INT_OVERWRITE)
 		zeroize_key(tmpstr, s_len);
 
 	gnutls_free(tmpstr);
@@ -365,12 +412,23 @@ int
 _gnutls_x509_write_int(ASN1_TYPE node, const char *value, bigint_t mpi,
 		       int lz)
 {
-	return __gnutls_x509_write_int(node, value, mpi, lz, 0);
+	return __gnutls_x509_write_int(node, value, mpi,
+				       lz ? GNUTLS_X509_INT_LZ : 0);
 }
 
 int
 _gnutls_x509_write_key_int(ASN1_TYPE node, const char *value, bigint_t mpi,
 		       int lz)
 {
-	return __gnutls_x509_write_int(node, value, mpi, lz, 1);
+	return __gnutls_x509_write_int(node, value, mpi,
+				       (lz ? GNUTLS_X509_INT_LZ : 0) |
+				       GNUTLS_X509_INT_OVERWRITE);
+}
+
+int
+_gnutls_x509_write_key_int_le(ASN1_TYPE node, const char *value, bigint_t mpi)
+{
+	return __gnutls_x509_write_int(node, value, mpi,
+				       GNUTLS_X509_INT_OVERWRITE |
+				       GNUTLS_X509_INT_LE);
 }
diff --git a/lib/mpi.h b/lib/mpi.h
index af3e37b775..2715c2ddc1 100644
--- a/lib/mpi.h
+++ b/lib/mpi.h
@@ -57,8 +57,10 @@ bigint_t _gnutls_mpi_random_modp(bigint_t, bigint_t p,
 #define _gnutls_prime_check _gnutls_mpi_ops.bigint_prime_check
 #define _gnutls_mpi_print(x,y,z) _gnutls_mpi_ops.bigint_print(x,y,z,GNUTLS_MPI_FORMAT_USG)
 #define _gnutls_mpi_print_lz(x,y,z) _gnutls_mpi_ops.bigint_print(x,y,z,GNUTLS_MPI_FORMAT_STD)
+#define _gnutls_mpi_print_le(x,y,z) _gnutls_mpi_ops.bigint_print(x,y,z,GNUTLS_MPI_FORMAT_ULE)
 #define _gnutls_mpi_copy _gnutls_mpi_ops.bigint_copy
 #define _gnutls_mpi_scan(r, b, s) _gnutls_mpi_ops.bigint_scan(r, b, s, GNUTLS_MPI_FORMAT_USG)
+#define _gnutls_mpi_scan_le(r, b, s) _gnutls_mpi_ops.bigint_scan(r, b, s, GNUTLS_MPI_FORMAT_ULE)
 
 inline static
 void _gnutls_mpi_release(bigint_t * x)
@@ -74,6 +76,8 @@ int _gnutls_mpi_init_scan(bigint_t * ret_mpi, const void *buffer,
 		     size_t nbytes);
 int _gnutls_mpi_init_scan_nz(bigint_t * ret_mpi, const void *buffer,
 			size_t nbytes);
+int _gnutls_mpi_init_scan_le(bigint_t * ret_mpi, const void *buffer,
+			     size_t nbytes);
 
 int _gnutls_mpi_dprint_lz(const bigint_t a, gnutls_datum_t * dest);
 int _gnutls_mpi_dprint(const bigint_t a, gnutls_datum_t * dest);
diff --git a/lib/x509/x509_int.h b/lib/x509/x509_int.h
index 77f673f656..8f8733b358 100644
--- a/lib/x509/x509_int.h
+++ b/lib/x509/x509_int.h
@@ -379,6 +379,11 @@ int _gnutls_x509_read_key_int(ASN1_TYPE node, const char *value,
 int _gnutls_x509_write_key_int(ASN1_TYPE node, const char *value, bigint_t mpi,
 			   int lz);
 
+int _gnutls_x509_read_key_int_le(ASN1_TYPE node, const char *value,
+				 bigint_t * ret_mpi);
+int _gnutls_x509_write_key_int_le(ASN1_TYPE node, const char *value,
+				  bigint_t mpi);
+
 int _gnutls_x509_read_pkalgo_params(ASN1_TYPE src, const char *src_name,
 				  gnutls_x509_spki_st *params, unsigned is_sig);
 int _gnutls_x509_write_sign_params(ASN1_TYPE dst, const char *dst_name,