2 files changed, 416 insertions, 157 deletions

diff --git a/crypto/xts.c b/crypto/xts.c
index 305343f22a02..410a2e299085 100644
--- a/crypto/xts.c
+++ b/crypto/xts.c
@@ -13,7 +13,8 @@
  * Software Foundation; either version 2 of the License, or (at your option)
  * any later version.
  */
-#include <crypto/algapi.h>
+#include <crypto/internal/skcipher.h>
+#include <crypto/scatterwalk.h>
 #include <linux/err.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
@@ -25,140 +26,320 @@
 #include <crypto/b128ops.h>
 #include <crypto/gf128mul.h>
 
+#define XTS_BUFFER_SIZE 128u
+
 struct priv {
-	struct crypto_cipher *child;
+	struct crypto_skcipher *child;
 	struct crypto_cipher *tweak;
 };
 
-static int setkey(struct crypto_tfm *parent, const u8 *key,
+struct xts_instance_ctx {
+	struct crypto_skcipher_spawn spawn;
+	char name[CRYPTO_MAX_ALG_NAME];
+};
+
+struct rctx {
+	be128 buf[XTS_BUFFER_SIZE / sizeof(be128)];
+
+	be128 t;
+
+	be128 *ext;
+
+	struct scatterlist srcbuf[2];
+	struct scatterlist dstbuf[2];
+	struct scatterlist *src;
+	struct scatterlist *dst;
+
+	unsigned int left;
+
+	struct skcipher_request subreq;
+};
+
+static int setkey(struct crypto_skcipher *parent, const u8 *key,
 		  unsigned int keylen)
 {
-	struct priv *ctx = crypto_tfm_ctx(parent);
-	struct crypto_cipher *child = ctx->tweak;
+	struct priv *ctx = crypto_skcipher_ctx(parent);
+	struct crypto_skcipher *child;
+	struct crypto_cipher *tweak;
 	int err;
 
-	err = xts_check_key(parent, key, keylen);
+	err = xts_verify_key(parent, key, keylen);
 	if (err)
 		return err;
 
+	keylen /= 2;
+
 	/* we need two cipher instances: one to compute the initial 'tweak'
 	 * by encrypting the IV (usually the 'plain' iv) and the other
 	 * one to encrypt and decrypt the data */
 
 	/* tweak cipher, uses Key2 i.e. the second half of *key */
-	crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
-	crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
+	tweak = ctx->tweak;
+	crypto_cipher_clear_flags(tweak, CRYPTO_TFM_REQ_MASK);
+	crypto_cipher_set_flags(tweak, crypto_skcipher_get_flags(parent) &
 				       CRYPTO_TFM_REQ_MASK);
-	err = crypto_cipher_setkey(child, key + keylen/2, keylen/2);
+	err = crypto_cipher_setkey(tweak, key + keylen, keylen);
+	crypto_skcipher_set_flags(parent, crypto_cipher_get_flags(tweak) &
+					  CRYPTO_TFM_RES_MASK);
 	if (err)
 		return err;
 
-	crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
-				     CRYPTO_TFM_RES_MASK);
-
+	/* data cipher, uses Key1 i.e. the first half of *key */
 	child = ctx->child;
+	crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
+	crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) &
+					 CRYPTO_TFM_REQ_MASK);
+	err = crypto_skcipher_setkey(child, key, keylen);
+	crypto_skcipher_set_flags(parent, crypto_skcipher_get_flags(child) &
+					  CRYPTO_TFM_RES_MASK);
 
-	/* data cipher, uses Key1 i.e. the first half of *key */
-	crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
-	crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
-				       CRYPTO_TFM_REQ_MASK);
-	err = crypto_cipher_setkey(child, key, keylen/2);
-	if (err)
-		return err;
+	return err;
+}
 
-	crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
-				     CRYPTO_TFM_RES_MASK);
+static int post_crypt(struct skcipher_request *req)
+{
+	struct rctx *rctx = skcipher_request_ctx(req);
+	be128 *buf = rctx->ext ?: rctx->buf;
+	struct skcipher_request *subreq;
+	const int bs = XTS_BLOCK_SIZE;
+	struct skcipher_walk w;
+	struct scatterlist *sg;
+	unsigned offset;
+	int err;
 
-	return 0;
-}
+	subreq = &rctx->subreq;
+	err = skcipher_walk_virt(&w, subreq, false);
 
-struct sinfo {
-	be128 *t;
-	struct crypto_tfm *tfm;
-	void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
-};
+	while (w.nbytes) {
+		unsigned int avail = w.nbytes;
+		be128 *wdst;
 
-static inline void xts_round(struct sinfo *s, void *dst, const void *src)
-{
-	be128_xor(dst, s->t, src);		/* PP <- T xor P */
-	s->fn(s->tfm, dst, dst);		/* CC <- E(Key1,PP) */
-	be128_xor(dst, dst, s->t);		/* C <- T xor CC */
+		wdst = w.dst.virt.addr;
+
+		do {
+			be128_xor(wdst, buf++, wdst);
+			wdst++;
+		} while ((avail -= bs) >= bs);
+
+		err = skcipher_walk_done(&w, avail);
+	}
+
+	rctx->left -= subreq->cryptlen;
+
+	if (err || !rctx->left)
+		goto out;
+
+	rctx->dst = rctx->dstbuf;
+
+	scatterwalk_done(&w.out, 0, 1);
+	sg = w.out.sg;
+	offset = w.out.offset;
+
+	if (rctx->dst != sg) {
+		rctx->dst[0] = *sg;
+		sg_unmark_end(rctx->dst);
+		scatterwalk_crypto_chain(rctx->dst, sg_next(sg), 0, 2);
+	}
+	rctx->dst[0].length -= offset - sg->offset;
+	rctx->dst[0].offset = offset;
+
+out:
+	return err;
 }
 
-static int crypt(struct blkcipher_desc *d,
-		 struct blkcipher_walk *w, struct priv *ctx,
-		 void (*tw)(struct crypto_tfm *, u8 *, const u8 *),
-		 void (*fn)(struct crypto_tfm *, u8 *, const u8 *))
+static int pre_crypt(struct skcipher_request *req)
 {
-	int err;
-	unsigned int avail;
+	struct rctx *rctx = skcipher_request_ctx(req);
+	be128 *buf = rctx->ext ?: rctx->buf;
+	struct skcipher_request *subreq;
 	const int bs = XTS_BLOCK_SIZE;
-	struct sinfo s = {
-		.tfm = crypto_cipher_tfm(ctx->child),
-		.fn = fn
-	};
-	u8 *wsrc;
-	u8 *wdst;
-
-	err = blkcipher_walk_virt(d, w);
-	if (!w->nbytes)
-		return err;
+	struct skcipher_walk w;
+	struct scatterlist *sg;
+	unsigned cryptlen;
+	unsigned offset;
+	bool more;
+	int err;
 
-	s.t = (be128 *)w->iv;
-	avail = w->nbytes;
+	subreq = &rctx->subreq;
+	cryptlen = subreq->cryptlen;
 
-	wsrc = w->src.virt.addr;
-	wdst = w->dst.virt.addr;
+	more = rctx->left > cryptlen;
+	if (!more)
+		cryptlen = rctx->left;
 
-	/* calculate first value of T */
-	tw(crypto_cipher_tfm(ctx->tweak), w->iv, w->iv);
+	skcipher_request_set_crypt(subreq, rctx->src, rctx->dst,
+				   cryptlen, NULL);
 
-	goto first;
+	err = skcipher_walk_virt(&w, subreq, false);
 
-	for (;;) {
-		do {
-			gf128mul_x_ble(s.t, s.t);
+	while (w.nbytes) {
+		unsigned int avail = w.nbytes;
+		be128 *wsrc;
+		be128 *wdst;
 
-first:
-			xts_round(&s, wdst, wsrc);
+		wsrc = w.src.virt.addr;
+		wdst = w.dst.virt.addr;
 
-			wsrc += bs;
-			wdst += bs;
+		do {
+			*buf++ = rctx->t;
+			be128_xor(wdst++, &rctx->t, wsrc++);
+			gf128mul_x_ble(&rctx->t, &rctx->t);
 		} while ((avail -= bs) >= bs);
 
-		err = blkcipher_walk_done(d, w, avail);
-		if (!w->nbytes)
-			break;
+		err = skcipher_walk_done(&w, avail);
+	}
+
+	skcipher_request_set_crypt(subreq, rctx->dst, rctx->dst,
+				   cryptlen, NULL);
 
-		avail = w->nbytes;
+	if (err || !more)
+		goto out;
 
-		wsrc = w->src.virt.addr;
-		wdst = w->dst.virt.addr;
+	rctx->src = rctx->srcbuf;
+
+	scatterwalk_done(&w.in, 0, 1);
+	sg = w.in.sg;
+	offset = w.in.offset;
+
+	if (rctx->src != sg) {
+		rctx->src[0] = *sg;
+		sg_unmark_end(rctx->src);
+		scatterwalk_crypto_chain(rctx->src, sg_next(sg), 0, 2);
 	}
+	rctx->src[0].length -= offset - sg->offset;
+	rctx->src[0].offset = offset;
 
+out:
 	return err;
 }
 
-static int encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
-		   struct scatterlist *src, unsigned int nbytes)
+static int init_crypt(struct skcipher_request *req, crypto_completion_t done)
 {
-	struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
-	struct blkcipher_walk w;
+	struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
+	struct rctx *rctx = skcipher_request_ctx(req);
+	struct skcipher_request *subreq;
+	gfp_t gfp;
+
+	subreq = &rctx->subreq;
+	skcipher_request_set_tfm(subreq, ctx->child);
+	skcipher_request_set_callback(subreq, req->base.flags, done, req);
+
+	gfp = req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL :
+							   GFP_ATOMIC;
+	rctx->ext = NULL;
+
+	subreq->cryptlen = XTS_BUFFER_SIZE;
+	if (req->cryptlen > XTS_BUFFER_SIZE) {
+		subreq->cryptlen = min(req->cryptlen, (unsigned)PAGE_SIZE);
+		rctx->ext = kmalloc(subreq->cryptlen, gfp);
+	}
+
+	rctx->src = req->src;
+	rctx->dst = req->dst;
+	rctx->left = req->cryptlen;
 
-	blkcipher_walk_init(&w, dst, src, nbytes);
-	return crypt(desc, &w, ctx, crypto_cipher_alg(ctx->tweak)->cia_encrypt,
-		     crypto_cipher_alg(ctx->child)->cia_encrypt);
+	/* calculate first value of T */
+	crypto_cipher_encrypt_one(ctx->tweak, (u8 *)&rctx->t, req->iv);
+
+	return 0;
 }
 
-static int decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
-		   struct scatterlist *src, unsigned int nbytes)
+static void exit_crypt(struct skcipher_request *req)
 {
-	struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
-	struct blkcipher_walk w;
+	struct rctx *rctx = skcipher_request_ctx(req);
+
+	rctx->left = 0;
 
-	blkcipher_walk_init(&w, dst, src, nbytes);
-	return crypt(desc, &w, ctx, crypto_cipher_alg(ctx->tweak)->cia_encrypt,
-		     crypto_cipher_alg(ctx->child)->cia_decrypt);
+	if (rctx->ext)
+		kzfree(rctx->ext);
+}
+
+static int do_encrypt(struct skcipher_request *req, int err)
+{
+	struct rctx *rctx = skcipher_request_ctx(req);
+	struct skcipher_request *subreq;
+
+	subreq = &rctx->subreq;
+
+	while (!err && rctx->left) {
+		err = pre_crypt(req) ?:
+		      crypto_skcipher_encrypt(subreq) ?:
+		      post_crypt(req);
+
+		if (err == -EINPROGRESS ||
+		    (err == -EBUSY &&
+		     req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG))
+			return err;
+	}
+
+	exit_crypt(req);
+	return err;
+}
+
+static void encrypt_done(struct crypto_async_request *areq, int err)
+{
+	struct skcipher_request *req = areq->data;
+	struct skcipher_request *subreq;
+	struct rctx *rctx;
+
+	rctx = skcipher_request_ctx(req);
+	subreq = &rctx->subreq;
+	subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
+
+	err = do_encrypt(req, err ?: post_crypt(req));
+	if (rctx->left)
+		return;
+
+	skcipher_request_complete(req, err);
+}
+
+static int encrypt(struct skcipher_request *req)
+{
+	return do_encrypt(req, init_crypt(req, encrypt_done));
+}
+
+static int do_decrypt(struct skcipher_request *req, int err)
+{
+	struct rctx *rctx = skcipher_request_ctx(req);
+	struct skcipher_request *subreq;
+
+	subreq = &rctx->subreq;
+
+	while (!err && rctx->left) {
+		err = pre_crypt(req) ?:
+		      crypto_skcipher_decrypt(subreq) ?:
+		      post_crypt(req);
+
+		if (err == -EINPROGRESS ||
+		    (err == -EBUSY &&
+		     req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG))
+			return err;
+	}
+
+	exit_crypt(req);
+	return err;
+}
+
+static void decrypt_done(struct crypto_async_request *areq, int err)
+{
+	struct skcipher_request *req = areq->data;
+	struct skcipher_request *subreq;
+	struct rctx *rctx;
+
+	rctx = skcipher_request_ctx(req);
+	subreq = &rctx->subreq;
+	subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
+
+	err = do_decrypt(req, err ?: post_crypt(req));
+	if (rctx->left)
+		return;
+
+	skcipher_request_complete(req, err);
+}
+
+static int decrypt(struct skcipher_request *req)
+{
+	return do_decrypt(req, init_crypt(req, decrypt_done));
 }
 
 int xts_crypt(struct blkcipher_desc *desc, struct scatterlist *sdst,
@@ -233,112 +414,168 @@ first:
 }
 EXPORT_SYMBOL_GPL(xts_crypt);
 
-static int init_tfm(struct crypto_tfm *tfm)
+static int init_tfm(struct crypto_skcipher *tfm)
 {
-	struct crypto_cipher *cipher;
-	struct crypto_instance *inst = (void *)tfm->__crt_alg;
-	struct crypto_spawn *spawn = crypto_instance_ctx(inst);
-	struct priv *ctx = crypto_tfm_ctx(tfm);
-	u32 *flags = &tfm->crt_flags;
-
-	cipher = crypto_spawn_cipher(spawn);
-	if (IS_ERR(cipher))
-		return PTR_ERR(cipher);
-
-	if (crypto_cipher_blocksize(cipher) != XTS_BLOCK_SIZE) {
-		*flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
-		crypto_free_cipher(cipher);
-		return -EINVAL;
-	}
+	struct skcipher_instance *inst = skcipher_alg_instance(tfm);
+	struct xts_instance_ctx *ictx = skcipher_instance_ctx(inst);
+	struct priv *ctx = crypto_skcipher_ctx(tfm);
+	struct crypto_skcipher *child;
+	struct crypto_cipher *tweak;
 
-	ctx->child = cipher;
+	child = crypto_spawn_skcipher(&ictx->spawn);
+	if (IS_ERR(child))
+		return PTR_ERR(child);
 
-	cipher = crypto_spawn_cipher(spawn);
-	if (IS_ERR(cipher)) {
-		crypto_free_cipher(ctx->child);
-		return PTR_ERR(cipher);
-	}
+	ctx->child = child;
 
-	/* this check isn't really needed, leave it here just in case */
-	if (crypto_cipher_blocksize(cipher) != XTS_BLOCK_SIZE) {
-		crypto_free_cipher(cipher);
-		crypto_free_cipher(ctx->child);
-		*flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
-		return -EINVAL;
+	tweak = crypto_alloc_cipher(ictx->name, 0, 0);
+	if (IS_ERR(tweak)) {
+		crypto_free_skcipher(ctx->child);
+		return PTR_ERR(tweak);
 	}
 
-	ctx->tweak = cipher;
+	ctx->tweak = tweak;
+
+	crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(child) +
+					 sizeof(struct rctx));
 
 	return 0;
 }
 
-static void exit_tfm(struct crypto_tfm *tfm)
+static void exit_tfm(struct crypto_skcipher *tfm)
 {
-	struct priv *ctx = crypto_tfm_ctx(tfm);
-	crypto_free_cipher(ctx->child);
+	struct priv *ctx = crypto_skcipher_ctx(tfm);
+
+	crypto_free_skcipher(ctx->child);
 	crypto_free_cipher(ctx->tweak);
 }
 
-static struct crypto_instance *alloc(struct rtattr **tb)
+static void free(struct skcipher_instance *inst)
+{
+	crypto_drop_skcipher(skcipher_instance_ctx(inst));
+	kfree(inst);
+}
+
+static int create(struct crypto_template *tmpl, struct rtattr **tb)
 {
-	struct crypto_instance *inst;
-	struct crypto_alg *alg;
+	struct skcipher_instance *inst;
+	struct crypto_attr_type *algt;
+	struct xts_instance_ctx *ctx;
+	struct skcipher_alg *alg;
+	const char *cipher_name;
 	int err;
 
-	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
+	algt = crypto_get_attr_type(tb);
+	if (IS_ERR(algt))
+		return PTR_ERR(algt);
+
+	if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask)
+		return -EINVAL;
+
+	cipher_name = crypto_attr_alg_name(tb[1]);
+	if (IS_ERR(cipher_name))
+		return PTR_ERR(cipher_name);
+
+	inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
+	if (!inst)
+		return -ENOMEM;
+
+	ctx = skcipher_instance_ctx(inst);
+
+	crypto_set_skcipher_spawn(&ctx->spawn, skcipher_crypto_instance(inst));
+	err = crypto_grab_skcipher(&ctx->spawn, cipher_name, 0,
+				   crypto_requires_sync(algt->type,
+							algt->mask));
+	if (err == -ENOENT) {
+		err = -ENAMETOOLONG;
+		if (snprintf(ctx->name, CRYPTO_MAX_ALG_NAME, "ecb(%s)",
+			     cipher_name) >= CRYPTO_MAX_ALG_NAME)
+			goto err_free_inst;
+
+		err = crypto_grab_skcipher(&ctx->spawn, ctx->name, 0,
+					   crypto_requires_sync(algt->type,
+								algt->mask));
+	}
+
 	if (err)
-		return ERR_PTR(err);
+		goto err_free_inst;
 
-	alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
-				  CRYPTO_ALG_TYPE_MASK);
-	if (IS_ERR(alg))
-		return ERR_CAST(alg);
+	alg = crypto_skcipher_spawn_alg(&ctx->spawn);
 
-	inst = crypto_alloc_instance("xts", alg);
-	if (IS_ERR(inst))
-		goto out_put_alg;
+	err = -EINVAL;
+	if (alg->base.cra_blocksize != XTS_BLOCK_SIZE)
+		goto err_drop_spawn;
 
-	inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
-	inst->alg.cra_priority = alg->cra_priority;
-	inst->alg.cra_blocksize = alg->cra_blocksize;
+	if (crypto_skcipher_alg_ivsize(alg))
+		goto err_drop_spawn;
 
-	if (alg->cra_alignmask < 7)
-		inst->alg.cra_alignmask = 7;
-	else
-		inst->alg.cra_alignmask = alg->cra_alignmask;
+	err = crypto_inst_setname(skcipher_crypto_instance(inst), "xts",
+				  &alg->base);
+	if (err)
+		goto err_drop_spawn;
 
-	inst->alg.cra_type = &crypto_blkcipher_type;
+	err = -EINVAL;
+	cipher_name = alg->base.cra_name;
 
-	inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
-	inst->alg.cra_blkcipher.min_keysize =
-		2 * alg->cra_cipher.cia_min_keysize;
-	inst->alg.cra_blkcipher.max_keysize =
-		2 * alg->cra_cipher.cia_max_keysize;
+	/* Alas we screwed up the naming so we have to mangle the
+	 * cipher name.
+	 */
+	if (!strncmp(cipher_name, "ecb(", 4)) {
+		unsigned len;
 
-	inst->alg.cra_ctxsize = sizeof(struct priv);
+		len = strlcpy(ctx->name, cipher_name + 4, sizeof(ctx->name));
+		if (len < 2 || len >= sizeof(ctx->name))
+			goto err_drop_spawn;
 
-	inst->alg.cra_init = init_tfm;
-	inst->alg.cra_exit = exit_tfm;
+		if (ctx->name[len - 1] != ')')
+			goto err_drop_spawn;
 
-	inst->alg.cra_blkcipher.setkey = setkey;
-	inst->alg.cra_blkcipher.encrypt = encrypt;
-	inst->alg.cra_blkcipher.decrypt = decrypt;
+		ctx->name[len - 1] = 0;
 
-out_put_alg:
-	crypto_mod_put(alg);
-	return inst;
-}
+		if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
+			     "xts(%s)", ctx->name) >= CRYPTO_MAX_ALG_NAME)
+			return -ENAMETOOLONG;
+	} else
+		goto err_drop_spawn;
 
-static void free(struct crypto_instance *inst)
-{
-	crypto_drop_spawn(crypto_instance_ctx(inst));
+	inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;
+	inst->alg.base.cra_priority = alg->base.cra_priority;
+	inst->alg.base.cra_blocksize = XTS_BLOCK_SIZE;
+	inst->alg.base.cra_alignmask = alg->base.cra_alignmask |
+				       (__alignof__(u64) - 1);
+
+	inst->alg.ivsize = XTS_BLOCK_SIZE;
+	inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) * 2;
+	inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) * 2;
+
+	inst->alg.base.cra_ctxsize = sizeof(struct priv);
+
+	inst->alg.init = init_tfm;
+	inst->alg.exit = exit_tfm;
+
+	inst->alg.setkey = setkey;
+	inst->alg.encrypt = encrypt;
+	inst->alg.decrypt = decrypt;
+
+	inst->free = free;
+
+	err = skcipher_register_instance(tmpl, inst);
+	if (err)
+		goto err_drop_spawn;
+
+out:
+	return err;
+
+err_drop_spawn:
+	crypto_drop_skcipher(&ctx->spawn);
+err_free_inst:
 	kfree(inst);
+	goto out;
 }
 
 static struct crypto_template crypto_tmpl = {
 	.name = "xts",
-	.alloc = alloc,
-	.free = free,
+	.create = create,
 	.module = THIS_MODULE,
 };
 
diff --git a/include/crypto/xts.h b/include/crypto/xts.h
index ede6b97b24cc..77b630672b2c 100644
--- a/include/crypto/xts.h
+++ b/include/crypto/xts.h
@@ -2,8 +2,7 @@
 #define _CRYPTO_XTS_H
 
 #include <crypto/b128ops.h>
-#include <linux/crypto.h>
-#include <crypto/algapi.h>
+#include <crypto/internal/skcipher.h>
 #include <linux/fips.h>
 
 struct scatterlist;
@@ -51,4 +50,27 @@ static inline int xts_check_key(struct crypto_tfm *tfm,
 	return 0;
 }
 
+static inline int xts_verify_key(struct crypto_skcipher *tfm,
+				 const u8 *key, unsigned int keylen)
+{
+	/*
+	 * key consists of keys of equal size concatenated, therefore
+	 * the length must be even.
+	 */
+	if (keylen % 2) {
+		crypto_skcipher_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
+		return -EINVAL;
+	}
+
+	/* ensure that the AES and tweak key are not identical */
+	if ((fips_enabled || crypto_skcipher_get_flags(tfm) &
+			     CRYPTO_TFM_REQ_WEAK_KEY) &&
+	    !crypto_memneq(key, key + (keylen / 2), keylen / 2)) {
+		crypto_skcipher_set_flags(tfm, CRYPTO_TFM_RES_WEAK_KEY);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 #endif  /* _CRYPTO_XTS_H */