crypto: caam/qi2 - add support for more XTS key lengths

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: 226853ac ("crypto: caam/qi2 - add skcipher algorithms")
Cc: <stable@vger.kernel.org> # v4.20+
Signed-off-by: Andrei Botila <andrei.botila@nxp.com>
Reviewed-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/caam/caamalg_qi2.c

@@ -19,6 +19,7 @@
 #include <linux/fsl/mc.h>
 #include <soc/fsl/dpaa2-io.h>
 #include <soc/fsl/dpaa2-fd.h>
+#include <crypto/xts.h>
 #include <asm/unaligned.h>
 
 #define CAAM_CRA_PRIORITY	2000
@@ -81,6 +82,7 @@ struct caam_ctx {
 	struct alginfo adata;
 	struct alginfo cdata;
 	unsigned int authsize;
+	bool xts_key_fallback;
 	struct crypto_skcipher *fallback;
 };
 
@@ -1060,11 +1062,15 @@ static int xts_skcipher_setkey(struct crypto_skcipher *skcipher, const u8 *key,
 	u32 *desc;
 	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(dev, "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;
@@ -1469,7 +1475,8 @@ static int skcipher_encrypt(struct skcipher_request *req)
 	if (!req->cryptlen)
 		return 0;
 
-	if (ctx->fallback && xts_skcipher_ivsize(req)) {
+	if (ctx->fallback && (xts_skcipher_ivsize(req) ||
+			      ctx->xts_key_fallback)) {
 		skcipher_request_set_tfm(&caam_req->fallback_req, ctx->fallback);
 		skcipher_request_set_callback(&caam_req->fallback_req,
 					      req->base.flags,
@@ -1512,7 +1519,8 @@ static int skcipher_decrypt(struct skcipher_request *req)
 	if (!req->cryptlen)
 		return 0;
 
-	if (ctx->fallback && xts_skcipher_ivsize(req)) {
+	if (ctx->fallback && (xts_skcipher_ivsize(req) ||
+			      ctx->xts_key_fallback)) {
 		skcipher_request_set_tfm(&caam_req->fallback_req, ctx->fallback);
 		skcipher_request_set_callback(&caam_req->fallback_req,
 					      req->base.flags,