[PATCH 3/9] crypto: caam/qi2 - add fallback for XTS with more than 8B IV

[Andrei Botila]

From: Andrei Botila <andrei.botila@xxxxxxx>

A hardware limitation exists for CAAM until Era 9 which restricts
the accelerator to IVs with only 8 bytes. When CAAM has a lower era
a fallback is necessary to process 16 bytes IV.

Fixes: 226853ac3ebe ("crypto: caam/qi2 - add skcipher algorithms")
Cc: <stable@xxxxxxxxxxxxxxx> # v4.20+
Signed-off-by: Andrei Botila <andrei.botila@xxxxxxx>
---
 drivers/crypto/caam/caamalg_qi2.c | 79 +++++++++++++++++++++++++++++--
 drivers/crypto/caam/caamalg_qi2.h |  2 +
 2 files changed, 77 insertions(+), 4 deletions(-)

diff --git a/drivers/crypto/caam/caamalg_qi2.c b/drivers/crypto/caam/caamalg_qi2.c
index 66ae1d581168..a0b13bf6b528 100644
--- a/drivers/crypto/caam/caamalg_qi2.c
+++ b/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 <asm/unaligned.h>
 
 #define CAAM_CRA_PRIORITY	2000
 
@@ -80,6 +81,7 @@ struct caam_ctx {
 	struct alginfo adata;
 	struct alginfo cdata;
 	unsigned int authsize;
+	struct crypto_skcipher *fallback;
 };
 
 static void *dpaa2_caam_iova_to_virt(struct dpaa2_caam_priv *priv,
@@ -1056,12 +1058,17 @@ static int xts_skcipher_setkey(struct crypto_skcipher *skcipher, const u8 *key,
 	struct device *dev = ctx->dev;
 	struct caam_flc *flc;
 	u32 *desc;
+	int err;
 
 	if (keylen != 2 * AES_MIN_KEY_SIZE  && keylen != 2 * AES_MAX_KEY_SIZE) {
 		dev_dbg(dev, "key size mismatch\n");
 		return -EINVAL;
 	}
 
+	err = crypto_skcipher_setkey(ctx->fallback, key, keylen);
+	if (err)
+		return err;
+
 	ctx->cdata.keylen = keylen;
 	ctx->cdata.key_virt = key;
 	ctx->cdata.key_inline = true;
@@ -1443,6 +1450,20 @@ static void skcipher_decrypt_done(void *cbk_ctx, u32 status)
 	skcipher_request_complete(req, ecode);
 }
 
+static bool xts_skcipher_ivsize(struct skcipher_request *req)
+{
+	struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
+	unsigned int ivsize = crypto_skcipher_ivsize(skcipher);
+	u64 size = 0;
+
+	if (IS_ALIGNED((unsigned long)req->iv, __alignof__(u64)))
+		size = *(u64 *)(req->iv + (ivsize / 2));
+	else
+		size = get_unaligned((u64 *)(req->iv + (ivsize / 2)));
+
+	return !!size;
+}
+
 static int skcipher_encrypt(struct skcipher_request *req)
 {
 	struct skcipher_edesc *edesc;
@@ -1454,6 +1475,18 @@ static int skcipher_encrypt(struct skcipher_request *req)
 	if (!req->cryptlen)
 		return 0;
 
+	if (ctx->fallback && xts_skcipher_ivsize(req)) {
+		skcipher_request_set_tfm(&caam_req->fallback_req, ctx->fallback);
+		skcipher_request_set_callback(&caam_req->fallback_req,
+					      req->base.flags,
+					      req->base.complete,
+					      req->base.data);
+		skcipher_request_set_crypt(&caam_req->fallback_req, req->src,
+					   req->dst, req->cryptlen, req->iv);
+
+		return crypto_skcipher_encrypt(&caam_req->fallback_req);
+	}
+
 	/* allocate extended descriptor */
 	edesc = skcipher_edesc_alloc(req);
 	if (IS_ERR(edesc))
@@ -1484,6 +1517,19 @@ static int skcipher_decrypt(struct skcipher_request *req)
 
 	if (!req->cryptlen)
 		return 0;
+
+	if (ctx->fallback && xts_skcipher_ivsize(req)) {
+		skcipher_request_set_tfm(&caam_req->fallback_req, ctx->fallback);
+		skcipher_request_set_callback(&caam_req->fallback_req,
+					      req->base.flags,
+					      req->base.complete,
+					      req->base.data);
+		skcipher_request_set_crypt(&caam_req->fallback_req, req->src,
+					   req->dst, req->cryptlen, req->iv);
+
+		return crypto_skcipher_decrypt(&caam_req->fallback_req);
+	}
+
 	/* allocate extended descriptor */
 	edesc = skcipher_edesc_alloc(req);
 	if (IS_ERR(edesc))
@@ -1537,9 +1583,29 @@ static int caam_cra_init_skcipher(struct crypto_skcipher *tfm)
 	struct skcipher_alg *alg = crypto_skcipher_alg(tfm);
 	struct caam_skcipher_alg *caam_alg =
 		container_of(alg, typeof(*caam_alg), skcipher);
+	struct caam_ctx *ctx = crypto_skcipher_ctx(tfm);
+	u32 alg_aai = caam_alg->caam.class1_alg_type & OP_ALG_AAI_MASK;
 
 	crypto_skcipher_set_reqsize(tfm, sizeof(struct caam_request));
-	return caam_cra_init(crypto_skcipher_ctx(tfm), &caam_alg->caam, false);
+
+	if (alg_aai == OP_ALG_AAI_XTS) {
+		const char *tfm_name = crypto_tfm_alg_name(&tfm->base);
+		struct crypto_skcipher *fallback;
+
+		fallback = crypto_alloc_skcipher(tfm_name, 0,
+						 CRYPTO_ALG_NEED_FALLBACK);
+		if (IS_ERR(fallback)) {
+			pr_err("Failed to allocate %s fallback: %ld\n",
+			       tfm_name, PTR_ERR(fallback));
+			return PTR_ERR(fallback);
+		}
+
+		ctx->fallback = fallback;
+		crypto_skcipher_set_reqsize(tfm, sizeof(struct caam_request) +
+					    crypto_skcipher_reqsize(fallback));
+	}
+
+	return caam_cra_init(ctx, &caam_alg->caam, false);
 }
 
 static int caam_cra_init_aead(struct crypto_aead *tfm)
@@ -1562,7 +1628,11 @@ static void caam_exit_common(struct caam_ctx *ctx)
 
 static void caam_cra_exit(struct crypto_skcipher *tfm)
 {
-	caam_exit_common(crypto_skcipher_ctx(tfm));
+	struct caam_ctx *ctx = crypto_skcipher_ctx(tfm);
+
+	if (ctx->fallback)
+		crypto_free_skcipher(ctx->fallback);
+	caam_exit_common(ctx);
 }
 
 static void caam_cra_exit_aead(struct crypto_aead *tfm)
@@ -1665,6 +1735,7 @@ static struct caam_skcipher_alg driver_algs[] = {
 			.base = {
 				.cra_name = "xts(aes)",
 				.cra_driver_name = "xts-aes-caam-qi2",
+				.cra_flags = CRYPTO_ALG_NEED_FALLBACK,
 				.cra_blocksize = AES_BLOCK_SIZE,
 			},
 			.setkey = xts_skcipher_setkey,
@@ -2912,8 +2983,8 @@ static void caam_skcipher_alg_init(struct caam_skcipher_alg *t_alg)
 	alg->base.cra_module = THIS_MODULE;
 	alg->base.cra_priority = CAAM_CRA_PRIORITY;
 	alg->base.cra_ctxsize = sizeof(struct caam_ctx);
-	alg->base.cra_flags = CRYPTO_ALG_ASYNC | CRYPTO_ALG_ALLOCATES_MEMORY |
-			      CRYPTO_ALG_KERN_DRIVER_ONLY;
+	alg->base.cra_flags |= (CRYPTO_ALG_ASYNC | CRYPTO_ALG_ALLOCATES_MEMORY |
+			      CRYPTO_ALG_KERN_DRIVER_ONLY);
 
 	alg->init = caam_cra_init_skcipher;
 	alg->exit = caam_cra_exit;
diff --git a/drivers/crypto/caam/caamalg_qi2.h b/drivers/crypto/caam/caamalg_qi2.h
index f29cb7bd7dd3..d35253407ade 100644
--- a/drivers/crypto/caam/caamalg_qi2.h
+++ b/drivers/crypto/caam/caamalg_qi2.h
@@ -13,6 +13,7 @@
 #include <linux/netdevice.h>
 #include "dpseci.h"
 #include "desc_constr.h"
+#include <crypto/skcipher.h>
 
 #define DPAA2_CAAM_STORE_SIZE	16
 /* NAPI weight *must* be a multiple of the store size. */
@@ -186,6 +187,7 @@ struct caam_request {
 	void (*cbk)(void *ctx, u32 err);
 	void *ctx;
 	void *edesc;
+	struct skcipher_request fallback_req;
 };
 
 /**
-- 
2.17.1