[PATCH v3 05/10] crypto: caam/qi - add support for more XTS key lengths

[Andrei Botila <andrei.botila@oss.nxp.com>]

From: Andrei Botila <andrei.botila@nxp.com>

CAAM accelerator only supports XTS-AES-128 and XTS-AES-256 since
it adheres strictly to the standard. All the other key lengths
are accepted and processed through a fallback as long as they pass
the xts_verify_key() checks.

Fixes: b189817cf789 ("crypto: caam/qi - add ablkcipher and authenc algorithms")
Cc: <stable@vger.kernel.org> # v4.12+
Signed-off-by: Andrei Botila <andrei.botila@nxp.com>
---
 drivers/crypto/caam/caamalg_qi.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/crypto/caam/caamalg_qi.c b/drivers/crypto/caam/caamalg_qi.c
index ee801370c879..30aceaf325d7 100644
--- a/drivers/crypto/caam/caamalg_qi.c
+++ b/drivers/crypto/caam/caamalg_qi.c
@@ -18,6 +18,7 @@
 #include "qi.h"
 #include "jr.h"
 #include "caamalg_desc.h"
+#include <crypto/xts.h>
 #include <asm/unaligned.h>
 
 /*
@@ -68,6 +69,7 @@ struct caam_ctx {
 	struct device *qidev;
 	spinlock_t lock;	/* Protects multiple init of driver context */
 	struct caam_drv_ctx *drv_ctx[NUM_OP];
+	bool xts_key_fallback;
 	struct crypto_skcipher *fallback;
 };
 
@@ -734,11 +736,15 @@ static int xts_skcipher_setkey(struct crypto_skcipher *skcipher, const u8 *key,
 	int ret = 0;
 	int err;
 
-	if (keylen != 2 * AES_MIN_KEY_SIZE  && keylen != 2 * AES_MAX_KEY_SIZE) {
+	err = xts_verify_key(skcipher, key, keylen);
+	if (err) {
 		dev_dbg(jrdev, "key size mismatch\n");
-		return -EINVAL;
+		return err;
 	}
 
+	if (keylen != 2 * AES_KEYSIZE_128 && keylen != 2 * AES_KEYSIZE_256)
+		ctx->xts_key_fallback = true;
+
 	err = crypto_skcipher_setkey(ctx->fallback, key, keylen);
 	if (err)
 		return err;
@@ -1402,7 +1408,8 @@ static inline int skcipher_crypt(struct skcipher_request *req, bool encrypt)
 	if (!req->cryptlen)
 		return 0;
 
-	if (ctx->fallback && xts_skcipher_ivsize(req)) {
+	if (ctx->fallback && (xts_skcipher_ivsize(req) ||
+			      ctx->xts_key_fallback)) {
 		struct caam_skcipher_req_ctx *rctx = skcipher_request_ctx(req);
 
 		skcipher_request_set_tfm(&rctx->fallback_req, ctx->fallback);
-- 
2.17.1