s390/crypto: Postpone the key split to key conversion

Store the input key material of paes-xts in a single key_blob
structure. The split of the input key material is postponed to the key
conversion. Split the key material only, if the returned protected
keytype requires a second protected key.

For clear key pairs, prepare a clearkey token for each key and convert
them separately to protected keys. Store the concatenated conversion
results as input key in the context. All other input keys are stored
as is.

Reviewed-by: Harald Freudenberger <freude@linux.ibm.com>
Signed-off-by: Holger Dengler <dengler@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

Author: holger-dengler

arch/s390/crypto/paes_s390.c

@@ -118,6 +118,40 @@ static inline int _key_to_kb(struct key_blob *kb,
 	return 0;
 }
 
+static inline int _xts_key_to_kb(struct key_blob *kb,
+				 const u8 *key,
+				 unsigned int keylen)
+{
+	size_t cklen = keylen / 2;
+
+	memset(kb->keybuf, 0, sizeof(kb->keybuf));
+
+	switch (keylen) {
+	case 32:
+	case 64:
+		/* clear key value, prepare pkey clear key tokens in keybuf */
+		kb->key = kb->keybuf;
+		kb->keylen  = make_clrkey_token(key, cklen, kb->key);
+		kb->keylen += make_clrkey_token(key + cklen, cklen,
+						kb->key + kb->keylen);
+		break;
+	default:
+		/* other key material, let pkey handle this */
+		if (keylen <= sizeof(kb->keybuf)) {
+			kb->key = kb->keybuf;
+		} else {
+			kb->key = kmalloc(keylen, GFP_KERNEL);
+			if (!kb->key)
+				return -ENOMEM;
+		}
+		memcpy(kb->key, key, keylen);
+		kb->keylen = keylen;
+		break;
+	}
+
+	return 0;
+}
+
 static inline void _free_kb_keybuf(struct key_blob *kb)
 {
 	if (kb->key && kb->key != kb->keybuf
@@ -135,7 +169,7 @@ struct s390_paes_ctx {
 };
 
 struct s390_pxts_ctx {
-	struct key_blob kb[2];
+	struct key_blob kb;
 	struct paes_protkey pk[2];
 	spinlock_t pk_lock;
 	unsigned long fc;
@@ -415,8 +449,7 @@ static int xts_paes_init(struct crypto_skcipher *tfm)
 {
 	struct s390_pxts_ctx *ctx = crypto_skcipher_ctx(tfm);
 
-	ctx->kb[0].key = NULL;
-	ctx->kb[1].key = NULL;
+	ctx->kb.key = NULL;
 	spin_lock_init(&ctx->pk_lock);
 
 	return 0;
@@ -426,24 +459,46 @@ static void xts_paes_exit(struct crypto_skcipher *tfm)
 {
 	struct s390_pxts_ctx *ctx = crypto_skcipher_ctx(tfm);
 
-	_free_kb_keybuf(&ctx->kb[0]);
-	_free_kb_keybuf(&ctx->kb[1]);
+	_free_kb_keybuf(&ctx->kb);
 }
 
 static inline int __xts_paes_convert_key(struct s390_pxts_ctx *ctx)
 {
 	struct paes_protkey pk0, pk1;
+	size_t split_keylen;
+	int rc;
 
 	pk0.len = sizeof(pk0.protkey);
 	pk1.len = sizeof(pk1.protkey);
 
-	if (__paes_keyblob2pkey(ctx->kb[0].key, ctx->kb[0].keylen, &pk0) ||
-	    __paes_keyblob2pkey(ctx->kb[1].key, ctx->kb[1].keylen, &pk1))
+	rc = __paes_keyblob2pkey(ctx->kb.key, ctx->kb.keylen, &pk0);
+	if (rc)
+		return rc;
+
+	switch (pk0.type) {
+	case PKEY_KEYTYPE_AES_128:
+	case PKEY_KEYTYPE_AES_256:
+		/* second keytoken required */
+		if (ctx->kb.keylen % 2)
+			return -EINVAL;
+		split_keylen = ctx->kb.keylen / 2;
+
+		rc = __paes_keyblob2pkey(ctx->kb.key + split_keylen,
+					 split_keylen, &pk1);
+		if (rc)
+			return rc;
+
+		if (pk0.type != pk1.type)
+			return -EINVAL;
+		break;
+	default:
+		/* unsupported protected keytype */
 		return -EINVAL;
+	}
 
 	spin_lock_bh(&ctx->pk_lock);
-	memcpy(&ctx->pk[0], &pk0, sizeof(pk0));
-	memcpy(&ctx->pk[1], &pk1, sizeof(pk1));
+	ctx->pk[0] = pk0;
+	ctx->pk[1] = pk1;
 	spin_unlock_bh(&ctx->pk_lock);
 
 	return 0;
@@ -452,12 +507,11 @@ static inline int __xts_paes_convert_key(struct s390_pxts_ctx *ctx)
 static inline int __xts_paes_set_key(struct s390_pxts_ctx *ctx)
 {
 	unsigned long fc;
+	int rc;
 
-	if (__xts_paes_convert_key(ctx))
-		return -EINVAL;
-
-	if (ctx->pk[0].type != ctx->pk[1].type)
-		return -EINVAL;
+	rc = __xts_paes_convert_key(ctx);
+	if (rc)
+		return rc;
 
 	/* Pick the correct function code based on the protected key type */
 	fc = (ctx->pk[0].type == PKEY_KEYTYPE_AES_128) ? CPACF_KM_PXTS_128 :
@@ -471,24 +525,19 @@ static inline int __xts_paes_set_key(struct s390_pxts_ctx *ctx)
 }
 
 static int xts_paes_set_key(struct crypto_skcipher *tfm, const u8 *in_key,
-			    unsigned int xts_key_len)
+			    unsigned int in_keylen)
 {
 	struct s390_pxts_ctx *ctx = crypto_skcipher_ctx(tfm);
-	unsigned int ckey_len, key_len;
 	u8 ckey[2 * AES_MAX_KEY_SIZE];
+	unsigned int ckey_len;
 	int rc;
 
-	if (xts_key_len % 2)
+	if ((in_keylen == 32 || in_keylen == 64) &&
+	    xts_verify_key(tfm, in_key, in_keylen))
 		return -EINVAL;
 
-	key_len = xts_key_len / 2;
-
-	_free_kb_keybuf(&ctx->kb[0]);
-	_free_kb_keybuf(&ctx->kb[1]);
-	rc = _key_to_kb(&ctx->kb[0], in_key, key_len);
-	if (rc)
-		return rc;
-	rc = _key_to_kb(&ctx->kb[1], in_key + key_len, key_len);
+	_free_kb_keybuf(&ctx->kb);
+	rc = _xts_key_to_kb(&ctx->kb, in_key, in_keylen);
 	if (rc)
 		return rc;