crypto: sig - Add interface for sign/verify

Split out the sign/verify functionality from the existing akcipher
interface.  Most algorithms in akcipher either support encryption
and decryption, or signing and verify.  Only one supports both.

As a signature algorithm may not support encryption at all, these
two should be spearated.

For now sig is simply a wrapper around akcipher as all algorithms
remain unchanged.  This is a first step and allows users to start
allocating sig instead of akcipher.

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

crypto/Kconfig

@@ -72,6 +72,15 @@ config CRYPTO_AEAD2
 	tristate
 	select CRYPTO_ALGAPI2
 
+config CRYPTO_SIG
+	tristate
+	select CRYPTO_SIG2
+	select CRYPTO_ALGAPI
+
+config CRYPTO_SIG2
+	tristate
+	select CRYPTO_ALGAPI2
+
 config CRYPTO_SKCIPHER
 	tristate
 	select CRYPTO_SKCIPHER2
@@ -143,6 +152,7 @@ config CRYPTO_MANAGER2
 	select CRYPTO_ACOMP2
 	select CRYPTO_AEAD2
 	select CRYPTO_AKCIPHER2
+	select CRYPTO_SIG2
 	select CRYPTO_HASH2
 	select CRYPTO_KPP2
 	select CRYPTO_RNG2

crypto/Makefile

@@ -25,6 +25,7 @@ crypto_hash-y += shash.o
 obj-$(CONFIG_CRYPTO_HASH2) += crypto_hash.o
 
 obj-$(CONFIG_CRYPTO_AKCIPHER2) += akcipher.o
+obj-$(CONFIG_CRYPTO_SIG2) += sig.o
 obj-$(CONFIG_CRYPTO_KPP2) += kpp.o
 
 dh_generic-y := dh.o

crypto/akcipher.c

@@ -18,18 +18,7 @@
 
 #include "internal.h"
 
-struct crypto_akcipher_sync_data {
-	struct crypto_akcipher *tfm;
-	const void *src;
-	void *dst;
-	unsigned int slen;
-	unsigned int dlen;
-
-	struct akcipher_request *req;
-	struct crypto_wait cwait;
-	struct scatterlist sg;
-	u8 *buf;
-};
+#define CRYPTO_ALG_TYPE_AHASH_MASK	0x0000000e
 
 static int __maybe_unused crypto_akcipher_report(
 	struct sk_buff *skb, struct crypto_alg *alg)
@@ -119,7 +108,7 @@ static const struct crypto_type crypto_akcipher_type = {
 	.report_stat = crypto_akcipher_report_stat,
 #endif
 	.maskclear = ~CRYPTO_ALG_TYPE_MASK,
-	.maskset = CRYPTO_ALG_TYPE_MASK,
+	.maskset = CRYPTO_ALG_TYPE_AHASH_MASK,
 	.type = CRYPTO_ALG_TYPE_AKCIPHER,
 	.tfmsize = offsetof(struct crypto_akcipher, base),
 };
@@ -200,7 +189,7 @@ int akcipher_register_instance(struct crypto_template *tmpl,
 }
 EXPORT_SYMBOL_GPL(akcipher_register_instance);
 
-static int crypto_akcipher_sync_prep(struct crypto_akcipher_sync_data *data)
+int crypto_akcipher_sync_prep(struct crypto_akcipher_sync_data *data)
 {
 	unsigned int reqsize = crypto_akcipher_reqsize(data->tfm);
 	unsigned int mlen = max(data->slen, data->dlen);
@@ -223,7 +212,7 @@ static int crypto_akcipher_sync_prep(struct crypto_akcipher_sync_data *data)
 	data->buf = buf;
 	memcpy(buf, data->src, data->slen);
 
-	sg = &data->sg;
+	sg = data->sg;
 	sg_init_one(sg, buf, mlen);
 	akcipher_request_set_crypt(req, sg, sg, data->slen, data->dlen);
 
@@ -233,16 +222,17 @@ static int crypto_akcipher_sync_prep(struct crypto_akcipher_sync_data *data)
 
 	return 0;
 }
+EXPORT_SYMBOL_GPL(crypto_akcipher_sync_prep);
 
-static int crypto_akcipher_sync_post(struct crypto_akcipher_sync_data *data,
-				     int err)
+int crypto_akcipher_sync_post(struct crypto_akcipher_sync_data *data, int err)
 {
 	err = crypto_wait_req(err, &data->cwait);
 	memcpy(data->dst, data->buf, data->dlen);
 	data->dlen = data->req->dst_len;
 	kfree_sensitive(data->req);
 	return err;
 }
+EXPORT_SYMBOL_GPL(crypto_akcipher_sync_post);
 
 int crypto_akcipher_sync_encrypt(struct crypto_akcipher *tfm,
 				 const void *src, unsigned int slen,
@@ -281,5 +271,34 @@ int crypto_akcipher_sync_decrypt(struct crypto_akcipher *tfm,
 }
 EXPORT_SYMBOL_GPL(crypto_akcipher_sync_decrypt);
 
+static void crypto_exit_akcipher_ops_sig(struct crypto_tfm *tfm)
+{
+	struct crypto_akcipher **ctx = crypto_tfm_ctx(tfm);
+
+	crypto_free_akcipher(*ctx);
+}
+
+int crypto_init_akcipher_ops_sig(struct crypto_tfm *tfm)
+{
+	struct crypto_akcipher **ctx = crypto_tfm_ctx(tfm);
+	struct crypto_alg *calg = tfm->__crt_alg;
+	struct crypto_akcipher *akcipher;
+
+	if (!crypto_mod_get(calg))
+		return -EAGAIN;
+
+	akcipher = crypto_create_tfm(calg, &crypto_akcipher_type);
+	if (IS_ERR(akcipher)) {
+		crypto_mod_put(calg);
+		return PTR_ERR(akcipher);
+	}
+
+	*ctx = akcipher;
+	tfm->exit = crypto_exit_akcipher_ops_sig;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(crypto_init_akcipher_ops_sig);
+
 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("Generic public key cipher type");

crypto/internal.h

@@ -18,9 +18,12 @@
 #include <linux/numa.h>
 #include <linux/refcount.h>
 #include <linux/rwsem.h>
+#include <linux/scatterlist.h>
 #include <linux/sched.h>
 #include <linux/types.h>
 
+struct akcipher_request;
+struct crypto_akcipher;
 struct crypto_instance;
 struct crypto_template;
 
@@ -32,6 +35,19 @@ struct crypto_larval {
 	bool test_started;
 };
 
+struct crypto_akcipher_sync_data {
+	struct crypto_akcipher *tfm;
+	const void *src;
+	void *dst;
+	unsigned int slen;
+	unsigned int dlen;
+
+	struct akcipher_request *req;
+	struct crypto_wait cwait;
+	struct scatterlist sg[2];
+	u8 *buf;
+};
+
 enum {
 	CRYPTOA_UNSPEC,
 	CRYPTOA_ALG,
@@ -111,6 +127,10 @@ void *crypto_create_tfm_node(struct crypto_alg *alg,
 void *crypto_clone_tfm(const struct crypto_type *frontend,
 		       struct crypto_tfm *otfm);
 
+int crypto_akcipher_sync_prep(struct crypto_akcipher_sync_data *data);
+int crypto_akcipher_sync_post(struct crypto_akcipher_sync_data *data, int err);
+int crypto_init_akcipher_ops_sig(struct crypto_tfm *tfm);
+
 static inline void *crypto_create_tfm(struct crypto_alg *alg,
 			const struct crypto_type *frontend)
 {

crypto/sig.c

@@ -0,0 +1,159 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Public Key Signature Algorithm
+ *
+ * Copyright (c) 2023 Herbert Xu <herbert@gondor.apana.org.au>
+ */
+
+#include <crypto/akcipher.h>
+#include <crypto/internal/sig.h>
+#include <linux/cryptouser.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/scatterlist.h>
+#include <linux/seq_file.h>
+#include <linux/string.h>
+#include <net/netlink.h>
+
+#include "internal.h"
+
+#define CRYPTO_ALG_TYPE_SIG_MASK	0x0000000e
+
+static const struct crypto_type crypto_sig_type;
+
+static inline struct crypto_sig *__crypto_sig_tfm(struct crypto_tfm *tfm)
+{
+	return container_of(tfm, struct crypto_sig, base);
+}
+
+static int crypto_sig_init_tfm(struct crypto_tfm *tfm)
+{
+	if (tfm->__crt_alg->cra_type != &crypto_sig_type)
+		return crypto_init_akcipher_ops_sig(tfm);
+
+	return 0;
+}
+
+static void __maybe_unused crypto_sig_show(struct seq_file *m,
+					   struct crypto_alg *alg)
+{
+	seq_puts(m, "type         : sig\n");
+}
+
+static int __maybe_unused crypto_sig_report(struct sk_buff *skb,
+					    struct crypto_alg *alg)
+{
+	struct crypto_report_akcipher rsig = {};
+
+	strscpy(rsig.type, "sig", sizeof(rsig.type));
+
+	return nla_put(skb, CRYPTOCFGA_REPORT_AKCIPHER, sizeof(rsig), &rsig);
+}
+
+static int __maybe_unused crypto_sig_report_stat(struct sk_buff *skb,
+						 struct crypto_alg *alg)
+{
+	struct crypto_stat_akcipher rsig = {};
+
+	strscpy(rsig.type, "sig", sizeof(rsig.type));
+
+	return nla_put(skb, CRYPTOCFGA_STAT_AKCIPHER, sizeof(rsig), &rsig);
+}
+
+static const struct crypto_type crypto_sig_type = {
+	.extsize = crypto_alg_extsize,
+	.init_tfm = crypto_sig_init_tfm,
+#ifdef CONFIG_PROC_FS
+	.show = crypto_sig_show,
+#endif
+#if IS_ENABLED(CONFIG_CRYPTO_USER)
+	.report = crypto_sig_report,
+#endif
+#ifdef CONFIG_CRYPTO_STATS
+	.report_stat = crypto_sig_report_stat,
+#endif
+	.maskclear = ~CRYPTO_ALG_TYPE_MASK,
+	.maskset = CRYPTO_ALG_TYPE_SIG_MASK,
+	.type = CRYPTO_ALG_TYPE_SIG,
+	.tfmsize = offsetof(struct crypto_sig, base),
+};
+
+struct crypto_sig *crypto_alloc_sig(const char *alg_name, u32 type, u32 mask)
+{
+	return crypto_alloc_tfm(alg_name, &crypto_sig_type, type, mask);
+}
+EXPORT_SYMBOL_GPL(crypto_alloc_sig);
+
+int crypto_sig_maxsize(struct crypto_sig *tfm)
+{
+	struct crypto_akcipher **ctx = crypto_sig_ctx(tfm);
+
+	return crypto_akcipher_maxsize(*ctx);
+}
+EXPORT_SYMBOL_GPL(crypto_sig_maxsize);
+
+int crypto_sig_sign(struct crypto_sig *tfm,
+		    const void *src, unsigned int slen,
+		    void *dst, unsigned int dlen)
+{
+	struct crypto_akcipher **ctx = crypto_sig_ctx(tfm);
+	struct crypto_akcipher_sync_data data = {
+		.tfm = *ctx,
+		.src = src,
+		.dst = dst,
+		.slen = slen,
+		.dlen = dlen,
+	};
+
+	return crypto_akcipher_sync_prep(&data) ?:
+	       crypto_akcipher_sync_post(&data,
+					 crypto_akcipher_sign(data.req));
+}
+EXPORT_SYMBOL_GPL(crypto_sig_sign);
+
+int crypto_sig_verify(struct crypto_sig *tfm,
+		      const void *src, unsigned int slen,
+		      const void *digest, unsigned int dlen)
+{
+	struct crypto_akcipher **ctx = crypto_sig_ctx(tfm);
+	struct crypto_akcipher_sync_data data = {
+		.tfm = *ctx,
+		.src = src,
+		.slen = slen,
+		.dlen = dlen,
+	};
+	int err;
+
+	err = crypto_akcipher_sync_prep(&data);
+	if (err)
+		return err;
+
+	sg_init_table(data.sg, 2);
+	sg_set_buf(&data.sg[0], src, slen);
+	sg_set_buf(&data.sg[1], digest, dlen);
+
+	return crypto_akcipher_sync_post(&data,
+					 crypto_akcipher_verify(data.req));
+}
+EXPORT_SYMBOL_GPL(crypto_sig_verify);
+
+int crypto_sig_set_pubkey(struct crypto_sig *tfm,
+			  const void *key, unsigned int keylen)
+{
+	struct crypto_akcipher **ctx = crypto_sig_ctx(tfm);
+
+	return crypto_akcipher_set_pub_key(*ctx, key, keylen);
+}
+EXPORT_SYMBOL_GPL(crypto_sig_set_pubkey);
+
+int crypto_sig_set_privkey(struct crypto_sig *tfm,
+			  const void *key, unsigned int keylen)
+{
+	struct crypto_akcipher **ctx = crypto_sig_ctx(tfm);
+
+	return crypto_akcipher_set_priv_key(*ctx, key, keylen);
+}
+EXPORT_SYMBOL_GPL(crypto_sig_set_privkey);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Public Key Signature Algorithms");

include/crypto/internal/sig.h

@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Public Key Signature Algorithm
+ *
+ * Copyright (c) 2023 Herbert Xu <herbert@gondor.apana.org.au>
+ */
+#ifndef _CRYPTO_INTERNAL_SIG_H
+#define _CRYPTO_INTERNAL_SIG_H
+
+#include <crypto/algapi.h>
+#include <crypto/sig.h>
+
+static inline void *crypto_sig_ctx(struct crypto_sig *tfm)
+{
+	return crypto_tfm_ctx(&tfm->base);
+}
+#endif