core: include parity in DES/DES3 key sizes

Update from GP 1.0 the parity bits are now included in the DES and DES3
key sizes. This is an incompatible change where 56, 112 and 168 key sizes
are replaced with 64, 128 and 192 respectively.

This changes the ABI in a way that it's not enough even to recompile the
TA.  In order to maintain backwards compatibility the configuration flag
CFG_COMPAT_GP10_DES is introduced (default y). The presence of the
parity bits is autodetected and this update is transparent to a TA which
hasn't been updated.

Reviewed-by: Jerome Forissier <jerome@forissier.org>
Acked-by: Etienne Carriere <etienne.carriere@linaro.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>

1 files changed, 59 insertions, 46 deletions

diff --git a/core/tee/tee_svc_cryp.c b/core/tee/tee_svc_cryp.c
index 52d6c780..67cffbca 100644
--- a/core/tee/tee_svc_cryp.c
+++ b/core/tee/tee_svc_cryp.c
@@ -402,21 +402,14 @@ static const struct tee_cryp_obj_type_props tee_cryp_obj_props[] = {
 	PROP(TEE_TYPE_AES, 64, 128, 256,	/* valid sizes 128, 192, 256 */
 		256 / 8 + sizeof(struct tee_cryp_obj_secret),
 		tee_cryp_obj_secret_value_attrs),
-	PROP(TEE_TYPE_DES, 56, 56, 56,
-		/*
-		* Valid size 56 without parity, note that we still allocate
-		* for 64 bits since the key is supplied with parity.
-		*/
-		64 / 8 + sizeof(struct tee_cryp_obj_secret),
-		tee_cryp_obj_secret_value_attrs),
-	PROP(TEE_TYPE_DES3, 56, 112, 168,
-		/*
-		* Valid sizes 112, 168 without parity, note that we still
-		* allocate for with space for the parity since the key is
-		* supplied with parity.
-		*/
-		192 / 8 + sizeof(struct tee_cryp_obj_secret),
-		tee_cryp_obj_secret_value_attrs),
+	PROP(TEE_TYPE_DES, 64, 64, 64,
+	     /* Valid size 64 with parity */
+	     64 / 8 + sizeof(struct tee_cryp_obj_secret),
+	     tee_cryp_obj_secret_value_attrs),
+	PROP(TEE_TYPE_DES3, 64, 128, 192,
+	     /* Valid sizes 128, 192 with parity */
+	     192 / 8 + sizeof(struct tee_cryp_obj_secret),
+	     tee_cryp_obj_secret_value_attrs),
 	PROP(TEE_TYPE_SM4, 128, 128, 128,
 		128 / 8 + sizeof(struct tee_cryp_obj_secret),
 		tee_cryp_obj_secret_value_attrs),
@@ -1206,6 +1199,36 @@ TEE_Result tee_obj_attr_copy_from(struct tee_obj *o, const struct tee_obj *src)
 	return TEE_SUCCESS;
 }
 
+static bool is_gp_legacy_des_key_size(TEE_ObjectType type, size_t sz)
+{
+	return IS_ENABLED(CFG_COMPAT_GP10_DES) &&
+	       ((type == TEE_TYPE_DES && sz == 56) ||
+		(type == TEE_TYPE_DES3 && (sz == 112 || sz == 168)));
+}
+
+static TEE_Result check_key_size(const struct tee_cryp_obj_type_props *props,
+				 size_t key_size)
+{
+	size_t sz = key_size;
+
+	/*
+	 * In GP Internal API Specification 1.0 the partity bits aren't
+	 * counted when telling the size of the key in bits so add them
+	 * here if missing.
+	 */
+	if (is_gp_legacy_des_key_size(props->obj_type, sz))
+		sz += sz / 7;
+
+	if (sz % props->quanta != 0)
+		return TEE_ERROR_NOT_SUPPORTED;
+	if (sz < props->min_size)
+		return TEE_ERROR_NOT_SUPPORTED;
+	if (sz > props->max_size)
+		return TEE_ERROR_NOT_SUPPORTED;
+
+	return TEE_SUCCESS;
+}
+
 TEE_Result tee_obj_set_type(struct tee_obj *o, uint32_t obj_type,
 			    size_t max_key_size)
 {
@@ -1230,13 +1253,10 @@ TEE_Result tee_obj_set_type(struct tee_obj *o, uint32_t obj_type,
 		if (!type_props)
 			return TEE_ERROR_NOT_SUPPORTED;
 
-		/* Check that maxKeySize follows restrictions */
-		if (max_key_size % type_props->quanta != 0)
-			return TEE_ERROR_NOT_SUPPORTED;
-		if (max_key_size < type_props->min_size)
-			return TEE_ERROR_NOT_SUPPORTED;
-		if (max_key_size > type_props->max_size)
-			return TEE_ERROR_NOT_SUPPORTED;
+		/* Check that max_key_size follows restrictions */
+		res = check_key_size(type_props, max_key_size);
+		if (res)
+			return res;
 
 		o->attr = calloc(1, type_props->alloc_size);
 		if (!o->attr)
@@ -1602,12 +1622,11 @@ static TEE_Result tee_svc_cryp_obj_populate_type(
 					return res;
 			} else {
 				TEE_ObjectType obj_type = o->info.objectType;
+				size_t sz = o->info.maxKeySize;
 
 				obj_size = attrs[n].content.ref.length * 8;
-
-				/* Drop the parity bits DES keys */
-				if (obj_type == TEE_TYPE_DES ||
-				    obj_type == TEE_TYPE_DES3)
+				/* Drop the parity bits for legacy objects */
+				if (is_gp_legacy_des_key_size(obj_type, sz))
 					obj_size -= obj_size / 8;
 			}
 			if (obj_size > o->info.maxKeySize)
@@ -1626,16 +1645,15 @@ static TEE_Result tee_svc_cryp_obj_populate_type(
 		}
 	}
 
-	/*
-	 * We have to do it like this because the parity bits aren't counted
-	 * when telling the size of the key in bits.
-	 */
-	if (o->info.objectType == TEE_TYPE_DES ||
-	    o->info.objectType == TEE_TYPE_DES3)
-		obj_size -= obj_size / 8; /* Exclude parity in size of key */
-
 	o->have_attrs = have_attrs;
 	o->info.keySize = obj_size;
+	/*
+	 * In GP Internal API Specification 1.0 the partity bits aren't
+	 * counted when telling the size of the key in bits so remove the
+	 * parity bits here.
+	 */
+	if (is_gp_legacy_des_key_size(o->info.objectType, o->info.maxKeySize))
+		o->info.keySize -= o->info.keySize / 8;
 
 	return TEE_SUCCESS;
 }
@@ -1915,13 +1933,10 @@ TEE_Result syscall_obj_generate_key(unsigned long obj, unsigned long key_size,
 	if (!type_props)
 		return TEE_ERROR_NOT_SUPPORTED;
 
-	/* Check that maxKeySize follows restrictions */
-	if (key_size % type_props->quanta != 0)
-		return TEE_ERROR_NOT_SUPPORTED;
-	if (key_size < type_props->min_size)
-		return TEE_ERROR_NOT_SUPPORTED;
-	if (key_size > type_props->max_size)
-		return TEE_ERROR_NOT_SUPPORTED;
+	/* Check that key_size follows restrictions */
+	res = check_key_size(type_props, key_size);
+	if (res)
+		return res;
 
 	size_t alloc_size = 0;
 
@@ -1957,13 +1972,11 @@ TEE_Result syscall_obj_generate_key(unsigned long obj, unsigned long key_size,
 		byte_size = key_size / 8;
 
 		/*
-		 * We have to do it like this because the parity bits aren't
-		 * counted when telling the size of the key in bits.
+		 * In GP Internal API Specification 1.0 the partity bits
+		 * aren't counted when telling the size of the key in bits.
 		 */
-		if (o->info.objectType == TEE_TYPE_DES ||
-		    o->info.objectType == TEE_TYPE_DES3) {
+		if (is_gp_legacy_des_key_size(o->info.objectType, key_size))
 			byte_size = (key_size + key_size / 7) / 8;
-		}
 
 		key = (struct tee_cryp_obj_secret *)o->attr;
 		if (byte_size > key->alloc_size) {