crypto: skcipher - Add lskcipher

Add a new API type lskcipher designed for taking straight kernel
pointers instead of SG lists.  Its relationship to skcipher will
be analogous to that between shash and ahash.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

5 files changed, 688 insertions, 19 deletions

diff --git a/crypto/Makefile b/crypto/Makefile
index 953a7e105e58c8..5ac6876f935a3f 100644
--- a/crypto/Makefile
+++ b/crypto/Makefile
@@ -16,7 +16,11 @@ obj-$(CONFIG_CRYPTO_ALGAPI2) += crypto_algapi.o
 obj-$(CONFIG_CRYPTO_AEAD2) += aead.o
 obj-$(CONFIG_CRYPTO_GENIV) += geniv.o
 
-obj-$(CONFIG_CRYPTO_SKCIPHER2) += skcipher.o
+crypto_skcipher-y += lskcipher.o
+crypto_skcipher-y += skcipher.o
+
+obj-$(CONFIG_CRYPTO_SKCIPHER2) += crypto_skcipher.o
+
 obj-$(CONFIG_CRYPTO_SEQIV) += seqiv.o
 obj-$(CONFIG_CRYPTO_ECHAINIV) += echainiv.o
 
diff --git a/crypto/cryptd.c b/crypto/cryptd.c
index bbcc368b6a5513..194a92d677b9a2 100644
--- a/crypto/cryptd.c
+++ b/crypto/cryptd.c
@@ -929,7 +929,7 @@ static int cryptd_create(struct crypto_template *tmpl, struct rtattr **tb)
 		return PTR_ERR(algt);
 
 	switch (algt->type & algt->mask & CRYPTO_ALG_TYPE_MASK) {
-	case CRYPTO_ALG_TYPE_SKCIPHER:
+	case CRYPTO_ALG_TYPE_LSKCIPHER:
 		return cryptd_create_skcipher(tmpl, tb, algt, &queue);
 	case CRYPTO_ALG_TYPE_HASH:
 		return cryptd_create_hash(tmpl, tb, algt, &queue);
diff --git a/crypto/lskcipher.c b/crypto/lskcipher.c
new file mode 100644
index 00000000000000..3343c6d955da71
--- /dev/null
+++ b/crypto/lskcipher.c
@@ -0,0 +1,594 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Linear symmetric key cipher operations.
+ *
+ * Generic encrypt/decrypt wrapper for ciphers.
+ *
+ * Copyright (c) 2023 Herbert Xu <herbert@gondor.apana.org.au>
+ */
+
+#include <linux/cryptouser.h>
+#include <linux/err.h>
+#include <linux/export.h>
+#include <linux/kernel.h>
+#include <linux/seq_file.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <net/netlink.h>
+#include "skcipher.h"
+
+static inline struct crypto_lskcipher *__crypto_lskcipher_cast(
+	struct crypto_tfm *tfm)
+{
+	return container_of(tfm, struct crypto_lskcipher, base);
+}
+
+static inline struct lskcipher_alg *__crypto_lskcipher_alg(
+	struct crypto_alg *alg)
+{
+	return container_of(alg, struct lskcipher_alg, co.base);
+}
+
+static inline struct crypto_istat_cipher *lskcipher_get_stat(
+	struct lskcipher_alg *alg)
+{
+	return skcipher_get_stat_common(&alg->co);
+}
+
+static inline int crypto_lskcipher_errstat(struct lskcipher_alg *alg, int err)
+{
+	struct crypto_istat_cipher *istat = lskcipher_get_stat(alg);
+
+	if (!IS_ENABLED(CONFIG_CRYPTO_STATS))
+		return err;
+
+	if (err)
+		atomic64_inc(&istat->err_cnt);
+
+	return err;
+}
+
+static int lskcipher_setkey_unaligned(struct crypto_lskcipher *tfm,
+				      const u8 *key, unsigned int keylen)
+{
+	unsigned long alignmask = crypto_lskcipher_alignmask(tfm);
+	struct lskcipher_alg *cipher = crypto_lskcipher_alg(tfm);
+	u8 *buffer, *alignbuffer;
+	unsigned long absize;
+	int ret;
+
+	absize = keylen + alignmask;
+	buffer = kmalloc(absize, GFP_ATOMIC);
+	if (!buffer)
+		return -ENOMEM;
+
+	alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
+	memcpy(alignbuffer, key, keylen);
+	ret = cipher->setkey(tfm, alignbuffer, keylen);
+	kfree_sensitive(buffer);
+	return ret;
+}
+
+int crypto_lskcipher_setkey(struct crypto_lskcipher *tfm, const u8 *key,
+			    unsigned int keylen)
+{
+	unsigned long alignmask = crypto_lskcipher_alignmask(tfm);
+	struct lskcipher_alg *cipher = crypto_lskcipher_alg(tfm);
+
+	if (keylen < cipher->co.min_keysize || keylen > cipher->co.max_keysize)
+		return -EINVAL;
+
+	if ((unsigned long)key & alignmask)
+		return lskcipher_setkey_unaligned(tfm, key, keylen);
+	else
+		return cipher->setkey(tfm, key, keylen);
+}
+EXPORT_SYMBOL_GPL(crypto_lskcipher_setkey);
+
+static int crypto_lskcipher_crypt_unaligned(
+	struct crypto_lskcipher *tfm, const u8 *src, u8 *dst, unsigned len,
+	u8 *iv, int (*crypt)(struct crypto_lskcipher *tfm, const u8 *src,
+			     u8 *dst, unsigned len, u8 *iv, bool final))
+{
+	unsigned ivsize = crypto_lskcipher_ivsize(tfm);
+	unsigned bs = crypto_lskcipher_blocksize(tfm);
+	unsigned cs = crypto_lskcipher_chunksize(tfm);
+	int err;
+	u8 *tiv;
+	u8 *p;
+
+	BUILD_BUG_ON(MAX_CIPHER_BLOCKSIZE > PAGE_SIZE ||
+		     MAX_CIPHER_ALIGNMASK >= PAGE_SIZE);
+
+	tiv = kmalloc(PAGE_SIZE, GFP_ATOMIC);
+	if (!tiv)
+		return -ENOMEM;
+
+	memcpy(tiv, iv, ivsize);
+
+	p = kmalloc(PAGE_SIZE, GFP_ATOMIC);
+	err = -ENOMEM;
+	if (!p)
+		goto out;
+
+	while (len >= bs) {
+		unsigned chunk = min((unsigned)PAGE_SIZE, len);
+		int err;
+
+		if (chunk > cs)
+			chunk &= ~(cs - 1);
+
+		memcpy(p, src, chunk);
+		err = crypt(tfm, p, p, chunk, tiv, true);
+		if (err)
+			goto out;
+
+		memcpy(dst, p, chunk);
+		src += chunk;
+		dst += chunk;
+		len -= chunk;
+	}
+
+	err = len ? -EINVAL : 0;
+
+out:
+	memcpy(iv, tiv, ivsize);
+	kfree_sensitive(p);
+	kfree_sensitive(tiv);
+	return err;
+}
+
+static int crypto_lskcipher_crypt(struct crypto_lskcipher *tfm, const u8 *src,
+				  u8 *dst, unsigned len, u8 *iv,
+				  int (*crypt)(struct crypto_lskcipher *tfm,
+					       const u8 *src, u8 *dst,
+					       unsigned len, u8 *iv,
+					       bool final))
+{
+	unsigned long alignmask = crypto_lskcipher_alignmask(tfm);
+	struct lskcipher_alg *alg = crypto_lskcipher_alg(tfm);
+	int ret;
+
+	if (((unsigned long)src | (unsigned long)dst | (unsigned long)iv) &
+	    alignmask) {
+		ret = crypto_lskcipher_crypt_unaligned(tfm, src, dst, len, iv,
+						       crypt);
+		goto out;
+	}
+
+	ret = crypt(tfm, src, dst, len, iv, true);
+
+out:
+	return crypto_lskcipher_errstat(alg, ret);
+}
+
+int crypto_lskcipher_encrypt(struct crypto_lskcipher *tfm, const u8 *src,
+			     u8 *dst, unsigned len, u8 *iv)
+{
+	struct lskcipher_alg *alg = crypto_lskcipher_alg(tfm);
+
+	if (IS_ENABLED(CONFIG_CRYPTO_STATS)) {
+		struct crypto_istat_cipher *istat = lskcipher_get_stat(alg);
+
+		atomic64_inc(&istat->encrypt_cnt);
+		atomic64_add(len, &istat->encrypt_tlen);
+	}
+
+	return crypto_lskcipher_crypt(tfm, src, dst, len, iv, alg->encrypt);
+}
+EXPORT_SYMBOL_GPL(crypto_lskcipher_encrypt);
+
+int crypto_lskcipher_decrypt(struct crypto_lskcipher *tfm, const u8 *src,
+			     u8 *dst, unsigned len, u8 *iv)
+{
+	struct lskcipher_alg *alg = crypto_lskcipher_alg(tfm);
+
+	if (IS_ENABLED(CONFIG_CRYPTO_STATS)) {
+		struct crypto_istat_cipher *istat = lskcipher_get_stat(alg);
+
+		atomic64_inc(&istat->decrypt_cnt);
+		atomic64_add(len, &istat->decrypt_tlen);
+	}
+
+	return crypto_lskcipher_crypt(tfm, src, dst, len, iv, alg->decrypt);
+}
+EXPORT_SYMBOL_GPL(crypto_lskcipher_decrypt);
+
+int crypto_lskcipher_setkey_sg(struct crypto_skcipher *tfm, const u8 *key,
+			       unsigned int keylen)
+{
+	struct crypto_lskcipher **ctx = crypto_skcipher_ctx(tfm);
+
+	return crypto_lskcipher_setkey(*ctx, key, keylen);
+}
+
+static int crypto_lskcipher_crypt_sg(struct skcipher_request *req,
+				     int (*crypt)(struct crypto_lskcipher *tfm,
+						  const u8 *src, u8 *dst,
+						  unsigned len, u8 *iv,
+						  bool final))
+{
+	struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
+	struct crypto_lskcipher **ctx = crypto_skcipher_ctx(skcipher);
+	struct crypto_lskcipher *tfm = *ctx;
+	struct skcipher_walk walk;
+	int err;
+
+	err = skcipher_walk_virt(&walk, req, false);
+
+	while (walk.nbytes) {
+		err = crypt(tfm, walk.src.virt.addr, walk.dst.virt.addr,
+			    walk.nbytes, walk.iv, walk.nbytes == walk.total);
+		err = skcipher_walk_done(&walk, err);
+	}
+
+	return err;
+}
+
+int crypto_lskcipher_encrypt_sg(struct skcipher_request *req)
+{
+	struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
+	struct crypto_lskcipher **ctx = crypto_skcipher_ctx(skcipher);
+	struct lskcipher_alg *alg = crypto_lskcipher_alg(*ctx);
+
+	return crypto_lskcipher_crypt_sg(req, alg->encrypt);
+}
+
+int crypto_lskcipher_decrypt_sg(struct skcipher_request *req)
+{
+	struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
+	struct crypto_lskcipher **ctx = crypto_skcipher_ctx(skcipher);
+	struct lskcipher_alg *alg = crypto_lskcipher_alg(*ctx);
+
+	return crypto_lskcipher_crypt_sg(req, alg->decrypt);
+}
+
+static void crypto_lskcipher_exit_tfm(struct crypto_tfm *tfm)
+{
+	struct crypto_lskcipher *skcipher = __crypto_lskcipher_cast(tfm);
+	struct lskcipher_alg *alg = crypto_lskcipher_alg(skcipher);
+
+	alg->exit(skcipher);
+}
+
+static int crypto_lskcipher_init_tfm(struct crypto_tfm *tfm)
+{
+	struct crypto_lskcipher *skcipher = __crypto_lskcipher_cast(tfm);
+	struct lskcipher_alg *alg = crypto_lskcipher_alg(skcipher);
+
+	if (alg->exit)
+		skcipher->base.exit = crypto_lskcipher_exit_tfm;
+
+	if (alg->init)
+		return alg->init(skcipher);
+
+	return 0;
+}
+
+static void crypto_lskcipher_free_instance(struct crypto_instance *inst)
+{
+	struct lskcipher_instance *skcipher =
+		container_of(inst, struct lskcipher_instance, s.base);
+
+	skcipher->free(skcipher);
+}
+
+static void __maybe_unused crypto_lskcipher_show(
+	struct seq_file *m, struct crypto_alg *alg)
+{
+	struct lskcipher_alg *skcipher = __crypto_lskcipher_alg(alg);
+
+	seq_printf(m, "type         : lskcipher\n");
+	seq_printf(m, "blocksize    : %u\n", alg->cra_blocksize);
+	seq_printf(m, "min keysize  : %u\n", skcipher->co.min_keysize);
+	seq_printf(m, "max keysize  : %u\n", skcipher->co.max_keysize);
+	seq_printf(m, "ivsize       : %u\n", skcipher->co.ivsize);
+	seq_printf(m, "chunksize    : %u\n", skcipher->co.chunksize);
+}
+
+static int __maybe_unused crypto_lskcipher_report(
+	struct sk_buff *skb, struct crypto_alg *alg)
+{
+	struct lskcipher_alg *skcipher = __crypto_lskcipher_alg(alg);
+	struct crypto_report_blkcipher rblkcipher;
+
+	memset(&rblkcipher, 0, sizeof(rblkcipher));
+
+	strscpy(rblkcipher.type, "lskcipher", sizeof(rblkcipher.type));
+	strscpy(rblkcipher.geniv, "<none>", sizeof(rblkcipher.geniv));
+
+	rblkcipher.blocksize = alg->cra_blocksize;
+	rblkcipher.min_keysize = skcipher->co.min_keysize;
+	rblkcipher.max_keysize = skcipher->co.max_keysize;
+	rblkcipher.ivsize = skcipher->co.ivsize;
+
+	return nla_put(skb, CRYPTOCFGA_REPORT_BLKCIPHER,
+		       sizeof(rblkcipher), &rblkcipher);
+}
+
+static int __maybe_unused crypto_lskcipher_report_stat(
+	struct sk_buff *skb, struct crypto_alg *alg)
+{
+	struct lskcipher_alg *skcipher = __crypto_lskcipher_alg(alg);
+	struct crypto_istat_cipher *istat;
+	struct crypto_stat_cipher rcipher;
+
+	istat = lskcipher_get_stat(skcipher);
+
+	memset(&rcipher, 0, sizeof(rcipher));
+
+	strscpy(rcipher.type, "cipher", sizeof(rcipher.type));
+
+	rcipher.stat_encrypt_cnt = atomic64_read(&istat->encrypt_cnt);
+	rcipher.stat_encrypt_tlen = atomic64_read(&istat->encrypt_tlen);
+	rcipher.stat_decrypt_cnt =  atomic64_read(&istat->decrypt_cnt);
+	rcipher.stat_decrypt_tlen = atomic64_read(&istat->decrypt_tlen);
+	rcipher.stat_err_cnt =  atomic64_read(&istat->err_cnt);
+
+	return nla_put(skb, CRYPTOCFGA_STAT_CIPHER, sizeof(rcipher), &rcipher);
+}
+
+static const struct crypto_type crypto_lskcipher_type = {
+	.extsize = crypto_alg_extsize,
+	.init_tfm = crypto_lskcipher_init_tfm,
+	.free = crypto_lskcipher_free_instance,
+#ifdef CONFIG_PROC_FS
+	.show = crypto_lskcipher_show,
+#endif
+#if IS_ENABLED(CONFIG_CRYPTO_USER)
+	.report = crypto_lskcipher_report,
+#endif
+#ifdef CONFIG_CRYPTO_STATS
+	.report_stat = crypto_lskcipher_report_stat,
+#endif
+	.maskclear = ~CRYPTO_ALG_TYPE_MASK,
+	.maskset = CRYPTO_ALG_TYPE_MASK,
+	.type = CRYPTO_ALG_TYPE_LSKCIPHER,
+	.tfmsize = offsetof(struct crypto_lskcipher, base),
+};
+
+static void crypto_lskcipher_exit_tfm_sg(struct crypto_tfm *tfm)
+{
+	struct crypto_lskcipher **ctx = crypto_tfm_ctx(tfm);
+
+	crypto_free_lskcipher(*ctx);
+}
+
+int crypto_init_lskcipher_ops_sg(struct crypto_tfm *tfm)
+{
+	struct crypto_lskcipher **ctx = crypto_tfm_ctx(tfm);
+	struct crypto_alg *calg = tfm->__crt_alg;
+	struct crypto_lskcipher *skcipher;
+
+	if (!crypto_mod_get(calg))
+		return -EAGAIN;
+
+	skcipher = crypto_create_tfm(calg, &crypto_lskcipher_type);
+	if (IS_ERR(skcipher)) {
+		crypto_mod_put(calg);
+		return PTR_ERR(skcipher);
+	}
+
+	*ctx = skcipher;
+	tfm->exit = crypto_lskcipher_exit_tfm_sg;
+
+	return 0;
+}
+
+int crypto_grab_lskcipher(struct crypto_lskcipher_spawn *spawn,
+			  struct crypto_instance *inst,
+			  const char *name, u32 type, u32 mask)
+{
+	spawn->base.frontend = &crypto_lskcipher_type;
+	return crypto_grab_spawn(&spawn->base, inst, name, type, mask);
+}
+EXPORT_SYMBOL_GPL(crypto_grab_lskcipher);
+
+struct crypto_lskcipher *crypto_alloc_lskcipher(const char *alg_name,
+						u32 type, u32 mask)
+{
+	return crypto_alloc_tfm(alg_name, &crypto_lskcipher_type, type, mask);
+}
+EXPORT_SYMBOL_GPL(crypto_alloc_lskcipher);
+
+static int lskcipher_prepare_alg(struct lskcipher_alg *alg)
+{
+	struct crypto_alg *base = &alg->co.base;
+	int err;
+
+	err = skcipher_prepare_alg_common(&alg->co);
+	if (err)
+		return err;
+
+	if (alg->co.chunksize & (alg->co.chunksize - 1))
+		return -EINVAL;
+
+	base->cra_type = &crypto_lskcipher_type;
+	base->cra_flags |= CRYPTO_ALG_TYPE_LSKCIPHER;
+
+	return 0;
+}
+
+int crypto_register_lskcipher(struct lskcipher_alg *alg)
+{
+	struct crypto_alg *base = &alg->co.base;
+	int err;
+
+	err = lskcipher_prepare_alg(alg);
+	if (err)
+		return err;
+
+	return crypto_register_alg(base);
+}
+EXPORT_SYMBOL_GPL(crypto_register_lskcipher);
+
+void crypto_unregister_lskcipher(struct lskcipher_alg *alg)
+{
+	crypto_unregister_alg(&alg->co.base);
+}
+EXPORT_SYMBOL_GPL(crypto_unregister_lskcipher);
+
+int crypto_register_lskciphers(struct lskcipher_alg *algs, int count)
+{
+	int i, ret;
+
+	for (i = 0; i < count; i++) {
+		ret = crypto_register_lskcipher(&algs[i]);
+		if (ret)
+			goto err;
+	}
+
+	return 0;
+
+err:
+	for (--i; i >= 0; --i)
+		crypto_unregister_lskcipher(&algs[i]);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(crypto_register_lskciphers);
+
+void crypto_unregister_lskciphers(struct lskcipher_alg *algs, int count)
+{
+	int i;
+
+	for (i = count - 1; i >= 0; --i)
+		crypto_unregister_lskcipher(&algs[i]);
+}
+EXPORT_SYMBOL_GPL(crypto_unregister_lskciphers);
+
+int lskcipher_register_instance(struct crypto_template *tmpl,
+				struct lskcipher_instance *inst)
+{
+	int err;
+
+	if (WARN_ON(!inst->free))
+		return -EINVAL;
+
+	err = lskcipher_prepare_alg(&inst->alg);
+	if (err)
+		return err;
+
+	return crypto_register_instance(tmpl, lskcipher_crypto_instance(inst));
+}
+EXPORT_SYMBOL_GPL(lskcipher_register_instance);
+
+static int lskcipher_setkey_simple(struct crypto_lskcipher *tfm, const u8 *key,
+				   unsigned int keylen)
+{
+	struct crypto_lskcipher *cipher = lskcipher_cipher_simple(tfm);
+
+	crypto_lskcipher_clear_flags(cipher, CRYPTO_TFM_REQ_MASK);
+	crypto_lskcipher_set_flags(cipher, crypto_lskcipher_get_flags(tfm) &
+				   CRYPTO_TFM_REQ_MASK);
+	return crypto_lskcipher_setkey(cipher, key, keylen);
+}
+
+static int lskcipher_init_tfm_simple(struct crypto_lskcipher *tfm)
+{
+	struct lskcipher_instance *inst = lskcipher_alg_instance(tfm);
+	struct crypto_lskcipher **ctx = crypto_lskcipher_ctx(tfm);
+	struct crypto_lskcipher_spawn *spawn;
+	struct crypto_lskcipher *cipher;
+
+	spawn = lskcipher_instance_ctx(inst);
+	cipher = crypto_spawn_lskcipher(spawn);
+	if (IS_ERR(cipher))
+		return PTR_ERR(cipher);
+
+	*ctx = cipher;
+	return 0;
+}
+
+static void lskcipher_exit_tfm_simple(struct crypto_lskcipher *tfm)
+{
+	struct crypto_lskcipher **ctx = crypto_lskcipher_ctx(tfm);
+
+	crypto_free_lskcipher(*ctx);
+}
+
+static void lskcipher_free_instance_simple(struct lskcipher_instance *inst)
+{
+	crypto_drop_lskcipher(lskcipher_instance_ctx(inst));
+	kfree(inst);
+}
+
+/**
+ * lskcipher_alloc_instance_simple - allocate instance of simple block cipher
+ *
+ * Allocate an lskcipher_instance for a simple block cipher mode of operation,
+ * e.g. cbc or ecb.  The instance context will have just a single crypto_spawn,
+ * that for the underlying cipher.  The {min,max}_keysize, ivsize, blocksize,
+ * alignmask, and priority are set from the underlying cipher but can be
+ * overridden if needed.  The tfm context defaults to
+ * struct crypto_lskcipher *, and default ->setkey(), ->init(), and
+ * ->exit() methods are installed.
+ *
+ * @tmpl: the template being instantiated
+ * @tb: the template parameters
+ *
+ * Return: a pointer to the new instance, or an ERR_PTR().  The caller still
+ *	   needs to register the instance.
+ */
+struct lskcipher_instance *lskcipher_alloc_instance_simple(
+	struct crypto_template *tmpl, struct rtattr **tb)
+{
+	u32 mask;
+	struct lskcipher_instance *inst;
+	struct crypto_lskcipher_spawn *spawn;
+	struct lskcipher_alg *cipher_alg;
+	int err;
+
+	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_LSKCIPHER, &mask);
+	if (err)
+		return ERR_PTR(err);
+
+	inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
+	if (!inst)
+		return ERR_PTR(-ENOMEM);
+
+	spawn = lskcipher_instance_ctx(inst);
+	err = crypto_grab_lskcipher(spawn,
+				    lskcipher_crypto_instance(inst),
+				    crypto_attr_alg_name(tb[1]), 0, mask);
+	if (err)
+		goto err_free_inst;
+	cipher_alg = crypto_lskcipher_spawn_alg(spawn);
+
+	err = crypto_inst_setname(lskcipher_crypto_instance(inst), tmpl->name,
+				  &cipher_alg->co.base);
+	if (err)
+		goto err_free_inst;
+
+	/* Don't allow nesting. */
+	err = -ELOOP;
+	if ((cipher_alg->co.base.cra_flags & CRYPTO_ALG_INSTANCE))
+		goto err_free_inst;
+
+	err = -EINVAL;
+	if (cipher_alg->co.ivsize)
+		goto err_free_inst;
+
+	inst->free = lskcipher_free_instance_simple;
+
+	/* Default algorithm properties, can be overridden */
+	inst->alg.co.base.cra_blocksize = cipher_alg->co.base.cra_blocksize;
+	inst->alg.co.base.cra_alignmask = cipher_alg->co.base.cra_alignmask;
+	inst->alg.co.base.cra_priority = cipher_alg->co.base.cra_priority;
+	inst->alg.co.min_keysize = cipher_alg->co.min_keysize;
+	inst->alg.co.max_keysize = cipher_alg->co.max_keysize;
+	inst->alg.co.ivsize = cipher_alg->co.base.cra_blocksize;
+
+	/* Use struct crypto_lskcipher * by default, can be overridden */
+	inst->alg.co.base.cra_ctxsize = sizeof(struct crypto_lskcipher *);
+	inst->alg.setkey = lskcipher_setkey_simple;
+	inst->alg.init = lskcipher_init_tfm_simple;
+	inst->alg.exit = lskcipher_exit_tfm_simple;
+
+	return inst;
+
+err_free_inst:
+	lskcipher_free_instance_simple(inst);
+	return ERR_PTR(err);
+}
+EXPORT_SYMBOL_GPL(lskcipher_alloc_instance_simple);
diff --git a/crypto/skcipher.c b/crypto/skcipher.c
index 7b275716cf4e3a..b9496dc8a609f6 100644
--- a/crypto/skcipher.c
+++ b/crypto/skcipher.c
@@ -24,8 +24,9 @@
 #include <linux/slab.h>
 #include <linux/string.h>
 #include <net/netlink.h>
+#include "skcipher.h"
 
-#include "internal.h"
+#define CRYPTO_ALG_TYPE_SKCIPHER_MASK	0x0000000e
 
 enum {
 	SKCIPHER_WALK_PHYS = 1 << 0,
@@ -43,6 +44,8 @@ struct skcipher_walk_buffer {
 	u8 buffer[];
 };
 
+static const struct crypto_type crypto_skcipher_type;
+
 static int skcipher_walk_next(struct skcipher_walk *walk);
 
 static inline void skcipher_map_src(struct skcipher_walk *walk)
@@ -89,11 +92,7 @@ static inline struct skcipher_alg *__crypto_skcipher_alg(
 static inline struct crypto_istat_cipher *skcipher_get_stat(
 	struct skcipher_alg *alg)
 {
-#ifdef CONFIG_CRYPTO_STATS
-	return &alg->stat;
-#else
-	return NULL;
-#endif
+	return skcipher_get_stat_common(&alg->co);
 }
 
 static inline int crypto_skcipher_errstat(struct skcipher_alg *alg, int err)
@@ -468,6 +467,7 @@ static int skcipher_walk_skcipher(struct skcipher_walk *walk,
 				  struct skcipher_request *req)
 {
 	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+	struct skcipher_alg *alg = crypto_skcipher_alg(tfm);
 
 	walk->total = req->cryptlen;
 	walk->nbytes = 0;
@@ -485,10 +485,14 @@ static int skcipher_walk_skcipher(struct skcipher_walk *walk,
 		       SKCIPHER_WALK_SLEEP : 0;
 
 	walk->blocksize = crypto_skcipher_blocksize(tfm);
-	walk->stride = crypto_skcipher_walksize(tfm);
 	walk->ivsize = crypto_skcipher_ivsize(tfm);
 	walk->alignmask = crypto_skcipher_alignmask(tfm);
 
+	if (alg->co.base.cra_type != &crypto_skcipher_type)
+		walk->stride = alg->co.chunksize;
+	else
+		walk->stride = alg->walksize;
+
 	return skcipher_walk_first(walk);
 }
 
@@ -616,6 +620,11 @@ int crypto_skcipher_setkey(struct crypto_skcipher *tfm, const u8 *key,
 	unsigned long alignmask = crypto_skcipher_alignmask(tfm);
 	int err;
 
+	if (cipher->co.base.cra_type != &crypto_skcipher_type) {
+		err = crypto_lskcipher_setkey_sg(tfm, key, keylen);
+		goto out;
+	}
+
 	if (keylen < cipher->min_keysize || keylen > cipher->max_keysize)
 		return -EINVAL;
 
@@ -624,6 +633,7 @@ int crypto_skcipher_setkey(struct crypto_skcipher *tfm, const u8 *key,
 	else
 		err = cipher->setkey(tfm, key, keylen);
 
+out:
 	if (unlikely(err)) {
 		skcipher_set_needkey(tfm);
 		return err;
@@ -649,6 +659,8 @@ int crypto_skcipher_encrypt(struct skcipher_request *req)
 
 	if (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
 		ret = -ENOKEY;
+	else if (alg->co.base.cra_type != &crypto_skcipher_type)
+		ret = crypto_lskcipher_encrypt_sg(req);
 	else
 		ret = alg->encrypt(req);
 
@@ -671,6 +683,8 @@ int crypto_skcipher_decrypt(struct skcipher_request *req)
 
 	if (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
 		ret = -ENOKEY;
+	else if (alg->co.base.cra_type != &crypto_skcipher_type)
+		ret = crypto_lskcipher_decrypt_sg(req);
 	else
 		ret = alg->decrypt(req);
 
@@ -693,6 +707,9 @@ static int crypto_skcipher_init_tfm(struct crypto_tfm *tfm)
 
 	skcipher_set_needkey(skcipher);
 
+	if (tfm->__crt_alg->cra_type != &crypto_skcipher_type)
+		return crypto_init_lskcipher_ops_sg(tfm);
+
 	if (alg->exit)
 		skcipher->base.exit = crypto_skcipher_exit_tfm;
 
@@ -702,6 +719,14 @@ static int crypto_skcipher_init_tfm(struct crypto_tfm *tfm)
 	return 0;
 }
 
+static unsigned int crypto_skcipher_extsize(struct crypto_alg *alg)
+{
+	if (alg->cra_type != &crypto_skcipher_type)
+		return sizeof(struct crypto_lskcipher *);
+
+	return crypto_alg_extsize(alg);
+}
+
 static void crypto_skcipher_free_instance(struct crypto_instance *inst)
 {
 	struct skcipher_instance *skcipher =
@@ -770,7 +795,7 @@ static int __maybe_unused crypto_skcipher_report_stat(
 }
 
 static const struct crypto_type crypto_skcipher_type = {
-	.extsize = crypto_alg_extsize,
+	.extsize = crypto_skcipher_extsize,
 	.init_tfm = crypto_skcipher_init_tfm,
 	.free = crypto_skcipher_free_instance,
 #ifdef CONFIG_PROC_FS
@@ -783,7 +808,7 @@ static const struct crypto_type crypto_skcipher_type = {
 	.report_stat = crypto_skcipher_report_stat,
 #endif
 	.maskclear = ~CRYPTO_ALG_TYPE_MASK,
-	.maskset = CRYPTO_ALG_TYPE_MASK,
+	.maskset = CRYPTO_ALG_TYPE_SKCIPHER_MASK,
 	.type = CRYPTO_ALG_TYPE_SKCIPHER,
 	.tfmsize = offsetof(struct crypto_skcipher, base),
 };
@@ -834,23 +859,18 @@ int crypto_has_skcipher(const char *alg_name, u32 type, u32 mask)
 }
 EXPORT_SYMBOL_GPL(crypto_has_skcipher);
 
-static int skcipher_prepare_alg(struct skcipher_alg *alg)
+int skcipher_prepare_alg_common(struct skcipher_alg_common *alg)
 {
-	struct crypto_istat_cipher *istat = skcipher_get_stat(alg);
+	struct crypto_istat_cipher *istat = skcipher_get_stat_common(alg);
 	struct crypto_alg *base = &alg->base;
 
-	if (alg->ivsize > PAGE_SIZE / 8 || alg->chunksize > PAGE_SIZE / 8 ||
-	    alg->walksize > PAGE_SIZE / 8)
+	if (alg->ivsize > PAGE_SIZE / 8 || alg->chunksize > PAGE_SIZE / 8)
 		return -EINVAL;
 
 	if (!alg->chunksize)
 		alg->chunksize = base->cra_blocksize;
-	if (!alg->walksize)
-		alg->walksize = alg->chunksize;
 
-	base->cra_type = &crypto_skcipher_type;
 	base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
-	base->cra_flags |= CRYPTO_ALG_TYPE_SKCIPHER;
 
 	if (IS_ENABLED(CONFIG_CRYPTO_STATS))
 		memset(istat, 0, sizeof(*istat));
@@ -858,6 +878,27 @@ static int skcipher_prepare_alg(struct skcipher_alg *alg)
 	return 0;
 }
 
+static int skcipher_prepare_alg(struct skcipher_alg *alg)
+{
+	struct crypto_alg *base = &alg->base;
+	int err;
+
+	err = skcipher_prepare_alg_common(&alg->co);
+	if (err)
+		return err;
+
+	if (alg->walksize > PAGE_SIZE / 8)
+		return -EINVAL;
+
+	if (!alg->walksize)
+		alg->walksize = alg->chunksize;
+
+	base->cra_type = &crypto_skcipher_type;
+	base->cra_flags |= CRYPTO_ALG_TYPE_SKCIPHER;
+
+	return 0;
+}
+
 int crypto_register_skcipher(struct skcipher_alg *alg)
 {
 	struct crypto_alg *base = &alg->base;
diff --git a/crypto/skcipher.h b/crypto/skcipher.h
new file mode 100644
index 00000000000000..6f1295f0fef24f
--- /dev/null
+++ b/crypto/skcipher.h
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Cryptographic API.
+ *
+ * Copyright (c) 2023 Herbert Xu <herbert@gondor.apana.org.au>
+ */
+#ifndef _LOCAL_CRYPTO_SKCIPHER_H
+#define _LOCAL_CRYPTO_SKCIPHER_H
+
+#include <crypto/internal/skcipher.h>
+#include "internal.h"
+
+static inline struct crypto_istat_cipher *skcipher_get_stat_common(
+	struct skcipher_alg_common *alg)
+{
+#ifdef CONFIG_CRYPTO_STATS
+	return &alg->stat;
+#else
+	return NULL;
+#endif
+}
+
+int crypto_lskcipher_setkey_sg(struct crypto_skcipher *tfm, const u8 *key,
+			       unsigned int keylen);
+int crypto_lskcipher_encrypt_sg(struct skcipher_request *req);
+int crypto_lskcipher_decrypt_sg(struct skcipher_request *req);
+int crypto_init_lskcipher_ops_sg(struct crypto_tfm *tfm);
+int skcipher_prepare_alg_common(struct skcipher_alg_common *alg);
+
+#endif	/* _LOCAL_CRYPTO_SKCIPHER_H */