[PATCH v2 04/12] crypto: caam/jr - add support for more XTS key lengths

[Andrei Botila]

From: Andrei Botila <andrei.botila@xxxxxxx>

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: c6415a6016bf ("crypto: caam - add support for acipher xts(aes)")
Cc: <stable@xxxxxxxxxxxxxxx> # v4.4+
Signed-off-by: Andrei Botila <andrei.botila@xxxxxxx>
---
 drivers/crypto/caam/caamalg.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/crypto/caam/caamalg.c b/drivers/crypto/caam/caamalg.c
index e85e740a5fbc..ba70db61a76d 100644
--- a/drivers/crypto/caam/caamalg.c
+++ b/drivers/crypto/caam/caamalg.c
@@ -57,6 +57,7 @@
 #include "key_gen.h"
 #include "caamalg_desc.h"
 #include <crypto/engine.h>
+#include <crypto/xts.h>
 #include <asm/unaligned.h>
 
 /*
@@ -115,6 +116,7 @@ struct caam_ctx {
 	struct alginfo adata;
 	struct alginfo cdata;
 	unsigned int authsize;
+	bool xts_key_fallback;
 	struct crypto_skcipher *fallback;
 };
 
@@ -835,11 +837,15 @@ 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(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;
@@ -1787,7 +1793,8 @@ 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