[PATCH 4/4] crypto: qat - fallback for xts with 192 bit keys

[Giovanni Cabiddu <giovanni.cabiddu@xxxxxxxxx>]

Forward requests to another provider if the key length is 192 bits as
this is not supported by the QAT accelerators.

This fixes the following issue reported by the extra self test:
alg: skcipher: qat_aes_xts setkey failed on test vector "random: len=3204
klen=48"; expected_error=0, actual_error=-22, flags=0x1

Signed-off-by: Giovanni Cabiddu <giovanni.cabiddu@xxxxxxxxx>
---
 drivers/crypto/qat/qat_common/qat_algs.c | 67 ++++++++++++++++++++++--
 1 file changed, 64 insertions(+), 3 deletions(-)

diff --git a/drivers/crypto/qat/qat_common/qat_algs.c b/drivers/crypto/qat/qat_common/qat_algs.c
index 77bdff0118f7..82c801ec1680 100644
--- a/drivers/crypto/qat/qat_common/qat_algs.c
+++ b/drivers/crypto/qat/qat_common/qat_algs.c
@@ -88,6 +88,8 @@ struct qat_alg_skcipher_ctx {
 	struct icp_qat_fw_la_bulk_req enc_fw_req;
 	struct icp_qat_fw_la_bulk_req dec_fw_req;
 	struct qat_crypto_instance *inst;
+	struct crypto_skcipher *ftfm;
+	bool fallback;
 };
 
 static int qat_get_inter_state_size(enum icp_qat_hw_auth_algo qat_hash_alg)
@@ -994,12 +996,25 @@ static int qat_alg_skcipher_ctr_setkey(struct crypto_skcipher *tfm,
 static int qat_alg_skcipher_xts_setkey(struct crypto_skcipher *tfm,
 				       const u8 *key, unsigned int keylen)
 {
+	struct qat_alg_skcipher_ctx *ctx = crypto_skcipher_ctx(tfm);
 	int ret;
 
 	ret = xts_verify_key(tfm, key, keylen);
 	if (ret)
 		return ret;
 
+	if (keylen >> 1 == AES_KEYSIZE_192) {
+		ret = crypto_skcipher_setkey(ctx->ftfm, key, keylen);
+		if (ret)
+			return ret;
+
+		ctx->fallback = true;
+
+		return 0;
+	}
+
+	ctx->fallback = false;
+
 	return qat_alg_skcipher_setkey(tfm, key, keylen,
 				       ICP_QAT_HW_CIPHER_XTS_MODE);
 }
@@ -1066,9 +1081,19 @@ static int qat_alg_skcipher_blk_encrypt(struct skcipher_request *req)
 
 static int qat_alg_skcipher_xts_encrypt(struct skcipher_request *req)
 {
+	struct crypto_skcipher *stfm = crypto_skcipher_reqtfm(req);
+	struct qat_alg_skcipher_ctx *ctx = crypto_skcipher_ctx(stfm);
+	struct skcipher_request *nreq = skcipher_request_ctx(req);
+
 	if (req->cryptlen < XTS_BLOCK_SIZE)
 		return -EINVAL;
 
+	if (ctx->fallback) {
+		memcpy(nreq, req, sizeof(*req));
+		skcipher_request_set_tfm(nreq, ctx->ftfm);
+		return crypto_skcipher_encrypt(nreq);
+	}
+
 	return qat_alg_skcipher_encrypt(req);
 }
 
@@ -1134,9 +1159,19 @@ static int qat_alg_skcipher_blk_decrypt(struct skcipher_request *req)
 
 static int qat_alg_skcipher_xts_decrypt(struct skcipher_request *req)
 {
+	struct crypto_skcipher *stfm = crypto_skcipher_reqtfm(req);
+	struct qat_alg_skcipher_ctx *ctx = crypto_skcipher_ctx(stfm);
+	struct skcipher_request *nreq = skcipher_request_ctx(req);
+
 	if (req->cryptlen < XTS_BLOCK_SIZE)
 		return -EINVAL;
 
+	if (ctx->fallback) {
+		memcpy(nreq, req, sizeof(*req));
+		skcipher_request_set_tfm(nreq, ctx->ftfm);
+		return crypto_skcipher_decrypt(nreq);
+	}
+
 	return qat_alg_skcipher_decrypt(req);
 }
 
@@ -1200,6 +1235,23 @@ static int qat_alg_skcipher_init_tfm(struct crypto_skcipher *tfm)
 	return 0;
 }
 
+static int qat_alg_skcipher_init_xts_tfm(struct crypto_skcipher *tfm)
+{
+	struct qat_alg_skcipher_ctx *ctx = crypto_skcipher_ctx(tfm);
+	int reqsize;
+
+	ctx->ftfm = crypto_alloc_skcipher("xts(aes)", 0, CRYPTO_ALG_ASYNC);
+	if (IS_ERR(ctx->ftfm))
+		return(PTR_ERR(ctx->ftfm));
+
+	reqsize = max(sizeof(struct qat_crypto_request),
+		      sizeof(struct skcipher_request) +
+		      crypto_skcipher_reqsize(ctx->ftfm));
+	crypto_skcipher_set_reqsize(tfm, reqsize);
+
+	return 0;
+}
+
 static void qat_alg_skcipher_exit_tfm(struct crypto_skcipher *tfm)
 {
 	struct qat_alg_skcipher_ctx *ctx = crypto_skcipher_ctx(tfm);
@@ -1227,6 +1279,15 @@ static void qat_alg_skcipher_exit_tfm(struct crypto_skcipher *tfm)
 	qat_crypto_put_instance(inst);
 }
 
+static void qat_alg_skcipher_exit_xts_tfm(struct crypto_skcipher *tfm)
+{
+	struct qat_alg_skcipher_ctx *ctx = crypto_skcipher_ctx(tfm);
+
+	if (ctx->ftfm)
+		crypto_free_skcipher(ctx->ftfm);
+
+	qat_alg_skcipher_exit_tfm(tfm);
+}
 
 static struct aead_alg qat_aeads[] = { {
 	.base = {
@@ -1321,14 +1382,14 @@ static struct skcipher_alg qat_skciphers[] = { {
 	.base.cra_name = "xts(aes)",
 	.base.cra_driver_name = "qat_aes_xts",
 	.base.cra_priority = 4001,
-	.base.cra_flags = CRYPTO_ALG_ASYNC,
+	.base.cra_flags = CRYPTO_ALG_ASYNC | CRYPTO_ALG_NEED_FALLBACK,
 	.base.cra_blocksize = AES_BLOCK_SIZE,
 	.base.cra_ctxsize = sizeof(struct qat_alg_skcipher_ctx),
 	.base.cra_alignmask = 0,
 	.base.cra_module = THIS_MODULE,
 
-	.init = qat_alg_skcipher_init_tfm,
-	.exit = qat_alg_skcipher_exit_tfm,
+	.init = qat_alg_skcipher_init_xts_tfm,
+	.exit = qat_alg_skcipher_exit_xts_tfm,
 	.setkey = qat_alg_skcipher_xts_setkey,
 	.decrypt = qat_alg_skcipher_xts_decrypt,
 	.encrypt = qat_alg_skcipher_xts_encrypt,
-- 
2.26.2