lib: crypto: add public key utility

Imported from linux kernel v5.3:
 asymmetric-type.h with changes marked as __UBOOT__
 asymmetric_type.c with changes marked as __UBOOT__
 public_key.h with changes marked as __UBOOT__
 public_key.c with changes marked as __UBOOT__

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>

include/crypto/public_key.h

@@ -0,0 +1,90 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* Asymmetric public-key algorithm definitions
+ *
+ * See Documentation/crypto/asymmetric-keys.txt
+ *
+ * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#ifndef _LINUX_PUBLIC_KEY_H
+#define _LINUX_PUBLIC_KEY_H
+
+#ifdef __UBOOT__
+#include <linux/types.h>
+#else
+#include <linux/keyctl.h>
+#endif
+#include <linux/oid_registry.h>
+
+/*
+ * Cryptographic data for the public-key subtype of the asymmetric key type.
+ *
+ * Note that this may include private part of the key as well as the public
+ * part.
+ */
+struct public_key {
+	void *key;
+	u32 keylen;
+	enum OID algo;
+	void *params;
+	u32 paramlen;
+	bool key_is_private;
+	const char *id_type;
+	const char *pkey_algo;
+};
+
+extern void public_key_free(struct public_key *key);
+
+/*
+ * Public key cryptography signature data
+ */
+struct public_key_signature {
+	struct asymmetric_key_id *auth_ids[2];
+	u8 *s;			/* Signature */
+	u32 s_size;		/* Number of bytes in signature */
+	u8 *digest;
+	u8 digest_size;		/* Number of bytes in digest */
+	const char *pkey_algo;
+	const char *hash_algo;
+	const char *encoding;
+};
+
+extern void public_key_signature_free(struct public_key_signature *sig);
+
+#ifndef __UBOOT__
+extern struct asymmetric_key_subtype public_key_subtype;
+
+struct key;
+struct key_type;
+union key_payload;
+
+extern int restrict_link_by_signature(struct key *dest_keyring,
+				      const struct key_type *type,
+				      const union key_payload *payload,
+				      struct key *trust_keyring);
+
+extern int restrict_link_by_key_or_keyring(struct key *dest_keyring,
+					   const struct key_type *type,
+					   const union key_payload *payload,
+					   struct key *trusted);
+
+extern int restrict_link_by_key_or_keyring_chain(struct key *trust_keyring,
+						 const struct key_type *type,
+						 const union key_payload *payload,
+						 struct key *trusted);
+
+extern int query_asymmetric_key(const struct kernel_pkey_params *,
+				struct kernel_pkey_query *);
+
+extern int encrypt_blob(struct kernel_pkey_params *, const void *, void *);
+extern int decrypt_blob(struct kernel_pkey_params *, const void *, void *);
+extern int create_signature(struct kernel_pkey_params *, const void *, void *);
+extern int verify_signature(const struct key *,
+			    const struct public_key_signature *);
+
+int public_key_verify_signature(const struct public_key *pkey,
+				const struct public_key_signature *sig);
+#endif /* !__UBOOT__ */
+
+#endif /* _LINUX_PUBLIC_KEY_H */

include/keys/asymmetric-type.h

@@ -0,0 +1,88 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* Asymmetric Public-key cryptography key type interface
+ *
+ * See Documentation/crypto/asymmetric-keys.txt
+ *
+ * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#ifndef _KEYS_ASYMMETRIC_TYPE_H
+#define _KEYS_ASYMMETRIC_TYPE_H
+
+#ifndef __UBOOT__
+#include <linux/key-type.h>
+#include <linux/verification.h>
+
+extern struct key_type key_type_asymmetric;
+
+/*
+ * The key payload is four words.  The asymmetric-type key uses them as
+ * follows:
+ */
+enum asymmetric_payload_bits {
+	asym_crypto,		/* The data representing the key */
+	asym_subtype,		/* Pointer to an asymmetric_key_subtype struct */
+	asym_key_ids,		/* Pointer to an asymmetric_key_ids struct */
+	asym_auth		/* The key's authorisation (signature, parent key ID) */
+};
+#endif /* !__UBOOT__ */
+
+/*
+ * Identifiers for an asymmetric key ID.  We have three ways of looking up a
+ * key derived from an X.509 certificate:
+ *
+ * (1) Serial Number & Issuer.  Non-optional.  This is the only valid way to
+ *     map a PKCS#7 signature to an X.509 certificate.
+ *
+ * (2) Issuer & Subject Unique IDs.  Optional.  These were the original way to
+ *     match X.509 certificates, but have fallen into disuse in favour of (3).
+ *
+ * (3) Auth & Subject Key Identifiers.  Optional.  SKIDs are only provided on
+ *     CA keys that are intended to sign other keys, so don't appear in end
+ *     user certificates unless forced.
+ *
+ * We could also support an PGP key identifier, which is just a SHA1 sum of the
+ * public key and certain parameters, but since we don't support PGP keys at
+ * the moment, we shall ignore those.
+ *
+ * What we actually do is provide a place where binary identifiers can be
+ * stashed and then compare against them when checking for an id match.
+ */
+struct asymmetric_key_id {
+	unsigned short	len;
+	unsigned char	data[];
+};
+
+struct asymmetric_key_ids {
+	void		*id[2];
+};
+
+extern bool asymmetric_key_id_same(const struct asymmetric_key_id *kid1,
+				   const struct asymmetric_key_id *kid2);
+
+extern bool asymmetric_key_id_partial(const struct asymmetric_key_id *kid1,
+				      const struct asymmetric_key_id *kid2);
+
+extern struct asymmetric_key_id *asymmetric_key_generate_id(const void *val_1,
+							    size_t len_1,
+							    const void *val_2,
+							    size_t len_2);
+#ifndef __UBOOT__
+static inline
+const struct asymmetric_key_ids *asymmetric_key_ids(const struct key *key)
+{
+	return key->payload.data[asym_key_ids];
+}
+
+extern struct key *find_asymmetric_key(struct key *keyring,
+				       const struct asymmetric_key_id *id_0,
+				       const struct asymmetric_key_id *id_1,
+				       bool partial);
+#endif
+
+/*
+ * The payload is at the discretion of the subtype.
+ */
+
+#endif /* _KEYS_ASYMMETRIC_TYPE_H */

lib/crypto/Kconfig

@@ -0,0 +1,19 @@
+menuconfig ASYMMETRIC_KEY_TYPE
+	bool "Asymmetric (public-key cryptographic) key Support"
+	help
+	  This option provides support for a key type that holds the data for
+	  the asymmetric keys used for public key cryptographic operations such
+	  as encryption, decryption, signature generation and signature
+	  verification.
+
+if ASYMMETRIC_KEY_TYPE
+
+config ASYMMETRIC_PUBLIC_KEY_SUBTYPE
+	bool "Asymmetric public-key crypto algorithm subtype"
+	help
+	  This option provides support for asymmetric public key type handling.
+	  If signature generation and/or verification are to be used,
+	  appropriate hash algorithms (such as SHA-1) must be available.
+	  ENOPKG will be reported if the requisite algorithm is unavailable.
+
+endif # ASYMMETRIC_KEY_TYPE

lib/crypto/Makefile

@@ -0,0 +1,10 @@
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Makefile for asymmetric cryptographic keys
+#
+
+obj-$(CONFIG_ASYMMETRIC_KEY_TYPE) += asymmetric_keys.o
+
+asymmetric_keys-y := asymmetric_type.o
+
+obj-$(CONFIG_ASYMMETRIC_PUBLIC_KEY_SUBTYPE) += public_key.o

lib/crypto/asymmetric_type.c

@@ -0,0 +1,668 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Asymmetric public-key cryptography key type
+ *
+ * See Documentation/crypto/asymmetric-keys.txt
+ *
+ * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+#ifndef __UBOOT__
+#include <keys/asymmetric-subtype.h>
+#include <keys/asymmetric-parser.h>
+#endif
+#include <crypto/public_key.h>
+#ifdef __UBOOT__
+#include <linux/compat.h>
+#include <linux/ctype.h>
+#include <linux/string.h>
+#else
+#include <linux/seq_file.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/ctype.h>
+#endif
+#ifdef __UBOOT__
+#include <keys/asymmetric-type.h>
+#else
+#include <keys/system_keyring.h>
+#include <keys/user-type.h>
+#include "asymmetric_keys.h"
+#endif
+
+MODULE_LICENSE("GPL");
+
+#ifndef __UBOOT__
+const char *const key_being_used_for[NR__KEY_BEING_USED_FOR] = {
+	[VERIFYING_MODULE_SIGNATURE]		= "mod sig",
+	[VERIFYING_FIRMWARE_SIGNATURE]		= "firmware sig",
+	[VERIFYING_KEXEC_PE_SIGNATURE]		= "kexec PE sig",
+	[VERIFYING_KEY_SIGNATURE]		= "key sig",
+	[VERIFYING_KEY_SELF_SIGNATURE]		= "key self sig",
+	[VERIFYING_UNSPECIFIED_SIGNATURE]	= "unspec sig",
+};
+EXPORT_SYMBOL_GPL(key_being_used_for);
+
+static LIST_HEAD(asymmetric_key_parsers);
+static DECLARE_RWSEM(asymmetric_key_parsers_sem);
+
+/**
+ * find_asymmetric_key - Find a key by ID.
+ * @keyring: The keys to search.
+ * @id_0: The first ID to look for or NULL.
+ * @id_1: The second ID to look for or NULL.
+ * @partial: Use partial match if true, exact if false.
+ *
+ * Find a key in the given keyring by identifier.  The preferred identifier is
+ * the id_0 and the fallback identifier is the id_1.  If both are given, the
+ * lookup is by the former, but the latter must also match.
+ */
+struct key *find_asymmetric_key(struct key *keyring,
+				const struct asymmetric_key_id *id_0,
+				const struct asymmetric_key_id *id_1,
+				bool partial)
+{
+	struct key *key;
+	key_ref_t ref;
+	const char *lookup;
+	char *req, *p;
+	int len;
+
+	BUG_ON(!id_0 && !id_1);
+
+	if (id_0) {
+		lookup = id_0->data;
+		len = id_0->len;
+	} else {
+		lookup = id_1->data;
+		len = id_1->len;
+	}
+
+	/* Construct an identifier "id:<keyid>". */
+	p = req = kmalloc(2 + 1 + len * 2 + 1, GFP_KERNEL);
+	if (!req)
+		return ERR_PTR(-ENOMEM);
+
+	if (partial) {
+		*p++ = 'i';
+		*p++ = 'd';
+	} else {
+		*p++ = 'e';
+		*p++ = 'x';
+	}
+	*p++ = ':';
+	p = bin2hex(p, lookup, len);
+	*p = 0;
+
+	pr_debug("Look up: \"%s\"\n", req);
+
+	ref = keyring_search(make_key_ref(keyring, 1),
+			     &key_type_asymmetric, req, true);
+	if (IS_ERR(ref))
+		pr_debug("Request for key '%s' err %ld\n", req, PTR_ERR(ref));
+	kfree(req);
+
+	if (IS_ERR(ref)) {
+		switch (PTR_ERR(ref)) {
+			/* Hide some search errors */
+		case -EACCES:
+		case -ENOTDIR:
+		case -EAGAIN:
+			return ERR_PTR(-ENOKEY);
+		default:
+			return ERR_CAST(ref);
+		}
+	}
+
+	key = key_ref_to_ptr(ref);
+	if (id_0 && id_1) {
+		const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
+
+		if (!kids->id[1]) {
+			pr_debug("First ID matches, but second is missing\n");
+			goto reject;
+		}
+		if (!asymmetric_key_id_same(id_1, kids->id[1])) {
+			pr_debug("First ID matches, but second does not\n");
+			goto reject;
+		}
+	}
+
+	pr_devel("<==%s() = 0 [%x]\n", __func__, key_serial(key));
+	return key;
+
+reject:
+	key_put(key);
+	return ERR_PTR(-EKEYREJECTED);
+}
+EXPORT_SYMBOL_GPL(find_asymmetric_key);
+#endif /* !__UBOOT__ */
+
+/**
+ * asymmetric_key_generate_id: Construct an asymmetric key ID
+ * @val_1: First binary blob
+ * @len_1: Length of first binary blob
+ * @val_2: Second binary blob
+ * @len_2: Length of second binary blob
+ *
+ * Construct an asymmetric key ID from a pair of binary blobs.
+ */
+struct asymmetric_key_id *asymmetric_key_generate_id(const void *val_1,
+						     size_t len_1,
+						     const void *val_2,
+						     size_t len_2)
+{
+	struct asymmetric_key_id *kid;
+
+	kid = kmalloc(sizeof(struct asymmetric_key_id) + len_1 + len_2,
+		      GFP_KERNEL);
+	if (!kid)
+		return ERR_PTR(-ENOMEM);
+	kid->len = len_1 + len_2;
+	memcpy(kid->data, val_1, len_1);
+	memcpy(kid->data + len_1, val_2, len_2);
+	return kid;
+}
+EXPORT_SYMBOL_GPL(asymmetric_key_generate_id);
+
+/**
+ * asymmetric_key_id_same - Return true if two asymmetric keys IDs are the same.
+ * @kid_1, @kid_2: The key IDs to compare
+ */
+bool asymmetric_key_id_same(const struct asymmetric_key_id *kid1,
+			    const struct asymmetric_key_id *kid2)
+{
+	if (!kid1 || !kid2)
+		return false;
+	if (kid1->len != kid2->len)
+		return false;
+	return memcmp(kid1->data, kid2->data, kid1->len) == 0;
+}
+EXPORT_SYMBOL_GPL(asymmetric_key_id_same);
+
+/**
+ * asymmetric_key_id_partial - Return true if two asymmetric keys IDs
+ * partially match
+ * @kid_1, @kid_2: The key IDs to compare
+ */
+bool asymmetric_key_id_partial(const struct asymmetric_key_id *kid1,
+			       const struct asymmetric_key_id *kid2)
+{
+	if (!kid1 || !kid2)
+		return false;
+	if (kid1->len < kid2->len)
+		return false;
+	return memcmp(kid1->data + (kid1->len - kid2->len),
+		      kid2->data, kid2->len) == 0;
+}
+EXPORT_SYMBOL_GPL(asymmetric_key_id_partial);
+
+#ifndef __UBOOT__
+/**
+ * asymmetric_match_key_ids - Search asymmetric key IDs
+ * @kids: The list of key IDs to check
+ * @match_id: The key ID we're looking for
+ * @match: The match function to use
+ */
+static bool asymmetric_match_key_ids(
+	const struct asymmetric_key_ids *kids,
+	const struct asymmetric_key_id *match_id,
+	bool (*match)(const struct asymmetric_key_id *kid1,
+		      const struct asymmetric_key_id *kid2))
+{
+	int i;
+
+	if (!kids || !match_id)
+		return false;
+	for (i = 0; i < ARRAY_SIZE(kids->id); i++)
+		if (match(kids->id[i], match_id))
+			return true;
+	return false;
+}
+
+/* helper function can be called directly with pre-allocated memory */
+inline int __asymmetric_key_hex_to_key_id(const char *id,
+				   struct asymmetric_key_id *match_id,
+				   size_t hexlen)
+{
+	match_id->len = hexlen;
+	return hex2bin(match_id->data, id, hexlen);
+}
+
+/**
+ * asymmetric_key_hex_to_key_id - Convert a hex string into a key ID.
+ * @id: The ID as a hex string.
+ */
+struct asymmetric_key_id *asymmetric_key_hex_to_key_id(const char *id)
+{
+	struct asymmetric_key_id *match_id;
+	size_t asciihexlen;
+	int ret;
+
+	if (!*id)
+		return ERR_PTR(-EINVAL);
+	asciihexlen = strlen(id);
+	if (asciihexlen & 1)
+		return ERR_PTR(-EINVAL);
+
+	match_id = kmalloc(sizeof(struct asymmetric_key_id) + asciihexlen / 2,
+			   GFP_KERNEL);
+	if (!match_id)
+		return ERR_PTR(-ENOMEM);
+	ret = __asymmetric_key_hex_to_key_id(id, match_id, asciihexlen / 2);
+	if (ret < 0) {
+		kfree(match_id);
+		return ERR_PTR(-EINVAL);
+	}
+	return match_id;
+}
+
+/*
+ * Match asymmetric keys by an exact match on an ID.
+ */
+static bool asymmetric_key_cmp(const struct key *key,
+			       const struct key_match_data *match_data)
+{
+	const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
+	const struct asymmetric_key_id *match_id = match_data->preparsed;
+
+	return asymmetric_match_key_ids(kids, match_id,
+					asymmetric_key_id_same);
+}
+
+/*
+ * Match asymmetric keys by a partial match on an IDs.
+ */
+static bool asymmetric_key_cmp_partial(const struct key *key,
+				       const struct key_match_data *match_data)
+{
+	const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
+	const struct asymmetric_key_id *match_id = match_data->preparsed;
+
+	return asymmetric_match_key_ids(kids, match_id,
+					asymmetric_key_id_partial);
+}
+
+/*
+ * Preparse the match criterion.  If we don't set lookup_type and cmp,
+ * the default will be an exact match on the key description.
+ *
+ * There are some specifiers for matching key IDs rather than by the key
+ * description:
+ *
+ *	"id:<id>" - find a key by partial match on any available ID
+ *	"ex:<id>" - find a key by exact match on any available ID
+ *
+ * These have to be searched by iteration rather than by direct lookup because
+ * the key is hashed according to its description.
+ */
+static int asymmetric_key_match_preparse(struct key_match_data *match_data)
+{
+	struct asymmetric_key_id *match_id;
+	const char *spec = match_data->raw_data;
+	const char *id;
+	bool (*cmp)(const struct key *, const struct key_match_data *) =
+		asymmetric_key_cmp;
+
+	if (!spec || !*spec)
+		return -EINVAL;
+	if (spec[0] == 'i' &&
+	    spec[1] == 'd' &&
+	    spec[2] == ':') {
+		id = spec + 3;
+		cmp = asymmetric_key_cmp_partial;
+	} else if (spec[0] == 'e' &&
+		   spec[1] == 'x' &&
+		   spec[2] == ':') {
+		id = spec + 3;
+	} else {
+		goto default_match;
+	}
+
+	match_id = asymmetric_key_hex_to_key_id(id);
+	if (IS_ERR(match_id))
+		return PTR_ERR(match_id);
+
+	match_data->preparsed = match_id;
+	match_data->cmp = cmp;
+	match_data->lookup_type = KEYRING_SEARCH_LOOKUP_ITERATE;
+	return 0;
+
+default_match:
+	return 0;
+}
+
+/*
+ * Free the preparsed the match criterion.
+ */
+static void asymmetric_key_match_free(struct key_match_data *match_data)
+{
+	kfree(match_data->preparsed);
+}
+
+/*
+ * Describe the asymmetric key
+ */
+static void asymmetric_key_describe(const struct key *key, struct seq_file *m)
+{
+	const struct asymmetric_key_subtype *subtype = asymmetric_key_subtype(key);
+	const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
+	const struct asymmetric_key_id *kid;
+	const unsigned char *p;
+	int n;
+
+	seq_puts(m, key->description);
+
+	if (subtype) {
+		seq_puts(m, ": ");
+		subtype->describe(key, m);
+
+		if (kids && kids->id[1]) {
+			kid = kids->id[1];
+			seq_putc(m, ' ');
+			n = kid->len;
+			p = kid->data;
+			if (n > 4) {
+				p += n - 4;
+				n = 4;
+			}
+			seq_printf(m, "%*phN", n, p);
+		}
+
+		seq_puts(m, " [");
+		/* put something here to indicate the key's capabilities */
+		seq_putc(m, ']');
+	}
+}
+
+/*
+ * Preparse a asymmetric payload to get format the contents appropriately for the
+ * internal payload to cut down on the number of scans of the data performed.
+ *
+ * We also generate a proposed description from the contents of the key that
+ * can be used to name the key if the user doesn't want to provide one.
+ */
+static int asymmetric_key_preparse(struct key_preparsed_payload *prep)
+{
+	struct asymmetric_key_parser *parser;
+	int ret;
+
+	pr_devel("==>%s()\n", __func__);
+
+	if (prep->datalen == 0)
+		return -EINVAL;
+
+	down_read(&asymmetric_key_parsers_sem);
+
+	ret = -EBADMSG;
+	list_for_each_entry(parser, &asymmetric_key_parsers, link) {
+		pr_debug("Trying parser '%s'\n", parser->name);
+
+		ret = parser->parse(prep);
+		if (ret != -EBADMSG) {
+			pr_debug("Parser recognised the format (ret %d)\n",
+				 ret);
+			break;
+		}
+	}
+
+	up_read(&asymmetric_key_parsers_sem);
+	pr_devel("<==%s() = %d\n", __func__, ret);
+	return ret;
+}
+
+/*
+ * Clean up the key ID list
+ */
+static void asymmetric_key_free_kids(struct asymmetric_key_ids *kids)
+{
+	int i;
+
+	if (kids) {
+		for (i = 0; i < ARRAY_SIZE(kids->id); i++)
+			kfree(kids->id[i]);
+		kfree(kids);
+	}
+}
+
+/*
+ * Clean up the preparse data
+ */
+static void asymmetric_key_free_preparse(struct key_preparsed_payload *prep)
+{
+	struct asymmetric_key_subtype *subtype = prep->payload.data[asym_subtype];
+	struct asymmetric_key_ids *kids = prep->payload.data[asym_key_ids];
+
+	pr_devel("==>%s()\n", __func__);
+
+	if (subtype) {
+		subtype->destroy(prep->payload.data[asym_crypto],
+				 prep->payload.data[asym_auth]);
+		module_put(subtype->owner);
+	}
+	asymmetric_key_free_kids(kids);
+	kfree(prep->description);
+}
+
+/*
+ * dispose of the data dangling from the corpse of a asymmetric key
+ */
+static void asymmetric_key_destroy(struct key *key)
+{
+	struct asymmetric_key_subtype *subtype = asymmetric_key_subtype(key);
+	struct asymmetric_key_ids *kids = key->payload.data[asym_key_ids];
+	void *data = key->payload.data[asym_crypto];
+	void *auth = key->payload.data[asym_auth];
+
+	key->payload.data[asym_crypto] = NULL;
+	key->payload.data[asym_subtype] = NULL;
+	key->payload.data[asym_key_ids] = NULL;
+	key->payload.data[asym_auth] = NULL;
+
+	if (subtype) {
+		subtype->destroy(data, auth);
+		module_put(subtype->owner);
+	}
+
+	asymmetric_key_free_kids(kids);
+}
+
+static struct key_restriction *asymmetric_restriction_alloc(
+	key_restrict_link_func_t check,
+	struct key *key)
+{
+	struct key_restriction *keyres =
+		kzalloc(sizeof(struct key_restriction), GFP_KERNEL);
+
+	if (!keyres)
+		return ERR_PTR(-ENOMEM);
+
+	keyres->check = check;
+	keyres->key = key;
+	keyres->keytype = &key_type_asymmetric;
+
+	return keyres;
+}
+
+/*
+ * look up keyring restrict functions for asymmetric keys
+ */
+static struct key_restriction *asymmetric_lookup_restriction(
+	const char *restriction)
+{
+	char *restrict_method;
+	char *parse_buf;
+	char *next;
+	struct key_restriction *ret = ERR_PTR(-EINVAL);
+
+	if (strcmp("builtin_trusted", restriction) == 0)
+		return asymmetric_restriction_alloc(
+			restrict_link_by_builtin_trusted, NULL);
+
+	if (strcmp("builtin_and_secondary_trusted", restriction) == 0)
+		return asymmetric_restriction_alloc(
+			restrict_link_by_builtin_and_secondary_trusted, NULL);
+
+	parse_buf = kstrndup(restriction, PAGE_SIZE, GFP_KERNEL);
+	if (!parse_buf)
+		return ERR_PTR(-ENOMEM);
+
+	next = parse_buf;
+	restrict_method = strsep(&next, ":");
+
+	if ((strcmp(restrict_method, "key_or_keyring") == 0) && next) {
+		char *key_text;
+		key_serial_t serial;
+		struct key *key;
+		key_restrict_link_func_t link_fn =
+			restrict_link_by_key_or_keyring;
+		bool allow_null_key = false;
+
+		key_text = strsep(&next, ":");
+
+		if (next) {
+			if (strcmp(next, "chain") != 0)
+				goto out;
+
+			link_fn = restrict_link_by_key_or_keyring_chain;
+			allow_null_key = true;
+		}
+
+		if (kstrtos32(key_text, 0, &serial) < 0)
+			goto out;
+
+		if ((serial == 0) && allow_null_key) {
+			key = NULL;
+		} else {
+			key = key_lookup(serial);
+			if (IS_ERR(key)) {
+				ret = ERR_CAST(key);
+				goto out;
+			}
+		}
+
+		ret = asymmetric_restriction_alloc(link_fn, key);
+		if (IS_ERR(ret))
+			key_put(key);
+	}
+
+out:
+	kfree(parse_buf);
+	return ret;
+}
+
+int asymmetric_key_eds_op(struct kernel_pkey_params *params,
+			  const void *in, void *out)
+{
+	const struct asymmetric_key_subtype *subtype;
+	struct key *key = params->key;
+	int ret;
+
+	pr_devel("==>%s()\n", __func__);
+
+	if (key->type != &key_type_asymmetric)
+		return -EINVAL;
+	subtype = asymmetric_key_subtype(key);
+	if (!subtype ||
+	    !key->payload.data[0])
+		return -EINVAL;
+	if (!subtype->eds_op)
+		return -ENOTSUPP;
+
+	ret = subtype->eds_op(params, in, out);
+
+	pr_devel("<==%s() = %d\n", __func__, ret);
+	return ret;
+}
+
+static int asymmetric_key_verify_signature(struct kernel_pkey_params *params,
+					   const void *in, const void *in2)
+{
+	struct public_key_signature sig = {
+		.s_size		= params->in2_len,
+		.digest_size	= params->in_len,
+		.encoding	= params->encoding,
+		.hash_algo	= params->hash_algo,
+		.digest		= (void *)in,
+		.s		= (void *)in2,
+	};
+
+	return verify_signature(params->key, &sig);
+}
+
+struct key_type key_type_asymmetric = {
+	.name			= "asymmetric",
+	.preparse		= asymmetric_key_preparse,
+	.free_preparse		= asymmetric_key_free_preparse,
+	.instantiate		= generic_key_instantiate,
+	.match_preparse		= asymmetric_key_match_preparse,
+	.match_free		= asymmetric_key_match_free,
+	.destroy		= asymmetric_key_destroy,
+	.describe		= asymmetric_key_describe,
+	.lookup_restriction	= asymmetric_lookup_restriction,
+	.asym_query		= query_asymmetric_key,
+	.asym_eds_op		= asymmetric_key_eds_op,
+	.asym_verify_signature	= asymmetric_key_verify_signature,
+};
+EXPORT_SYMBOL_GPL(key_type_asymmetric);
+
+/**
+ * register_asymmetric_key_parser - Register a asymmetric key blob parser
+ * @parser: The parser to register
+ */
+int register_asymmetric_key_parser(struct asymmetric_key_parser *parser)
+{
+	struct asymmetric_key_parser *cursor;
+	int ret;
+
+	down_write(&asymmetric_key_parsers_sem);
+
+	list_for_each_entry(cursor, &asymmetric_key_parsers, link) {
+		if (strcmp(cursor->name, parser->name) == 0) {
+			pr_err("Asymmetric key parser '%s' already registered\n",
+			       parser->name);
+			ret = -EEXIST;
+			goto out;
+		}
+	}
+
+	list_add_tail(&parser->link, &asymmetric_key_parsers);
+
+	pr_notice("Asymmetric key parser '%s' registered\n", parser->name);
+	ret = 0;
+
+out:
+	up_write(&asymmetric_key_parsers_sem);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(register_asymmetric_key_parser);
+
+/**
+ * unregister_asymmetric_key_parser - Unregister a asymmetric key blob parser
+ * @parser: The parser to unregister
+ */
+void unregister_asymmetric_key_parser(struct asymmetric_key_parser *parser)
+{
+	down_write(&asymmetric_key_parsers_sem);
+	list_del(&parser->link);
+	up_write(&asymmetric_key_parsers_sem);
+
+	pr_notice("Asymmetric key parser '%s' unregistered\n", parser->name);
+}
+EXPORT_SYMBOL_GPL(unregister_asymmetric_key_parser);
+
+/*
+ * Module stuff
+ */
+static int __init asymmetric_key_init(void)
+{
+	return register_key_type(&key_type_asymmetric);
+}
+
+static void __exit asymmetric_key_cleanup(void)
+{
+	unregister_key_type(&key_type_asymmetric);
+}
+
+module_init(asymmetric_key_init);
+module_exit(asymmetric_key_cleanup);
+#endif /* !__UBOOT__ */

lib/crypto/public_key.c

@@ -0,0 +1,376 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* In-software asymmetric public-key crypto subtype
+ *
+ * See Documentation/crypto/asymmetric-keys.txt
+ *
+ * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#define pr_fmt(fmt) "PKEY: "fmt
+#ifdef __UBOOT__
+#include <linux/compat.h>
+#else
+#include <linux/module.h>
+#include <linux/export.h>
+#endif
+#include <linux/kernel.h>
+#ifndef __UBOOT__
+#include <linux/slab.h>
+#include <linux/seq_file.h>
+#include <linux/scatterlist.h>
+#include <keys/asymmetric-subtype.h>
+#endif
+#include <crypto/public_key.h>
+#ifndef __UBOOT__
+#include <crypto/akcipher.h>
+#endif
+
+MODULE_DESCRIPTION("In-software asymmetric public-key subtype");
+MODULE_AUTHOR("Red Hat, Inc.");
+MODULE_LICENSE("GPL");
+
+#ifndef __UBOOT__
+/*
+ * Provide a part of a description of the key for /proc/keys.
+ */
+static void public_key_describe(const struct key *asymmetric_key,
+				struct seq_file *m)
+{
+	struct public_key *key = asymmetric_key->payload.data[asym_crypto];
+
+	if (key)
+		seq_printf(m, "%s.%s", key->id_type, key->pkey_algo);
+}
+#endif
+
+/*
+ * Destroy a public key algorithm key.
+ */
+void public_key_free(struct public_key *key)
+{
+	if (key) {
+		kfree(key->key);
+		kfree(key->params);
+		kfree(key);
+	}
+}
+EXPORT_SYMBOL_GPL(public_key_free);
+
+#ifdef __UBOOT__
+/*
+ * from <linux>/crypto/asymmetric_keys/signature.c
+ *
+ * Destroy a public key signature.
+ */
+void public_key_signature_free(struct public_key_signature *sig)
+{
+	int i;
+
+	if (sig) {
+		for (i = 0; i < ARRAY_SIZE(sig->auth_ids); i++)
+			free(sig->auth_ids[i]);
+		free(sig->s);
+		free(sig->digest);
+		free(sig);
+	}
+}
+EXPORT_SYMBOL_GPL(public_key_signature_free);
+
+#else
+/*
+ * Destroy a public key algorithm key.
+ */
+static void public_key_destroy(void *payload0, void *payload3)
+{
+	public_key_free(payload0);
+	public_key_signature_free(payload3);
+}
+
+/*
+ * Determine the crypto algorithm name.
+ */
+static
+int software_key_determine_akcipher(const char *encoding,
+				    const char *hash_algo,
+				    const struct public_key *pkey,
+				    char alg_name[CRYPTO_MAX_ALG_NAME])
+{
+	int n;
+
+	if (strcmp(encoding, "pkcs1") == 0) {
+		/* The data wangled by the RSA algorithm is typically padded
+		 * and encoded in some manner, such as EMSA-PKCS1-1_5 [RFC3447
+		 * sec 8.2].
+		 */
+		if (!hash_algo)
+			n = snprintf(alg_name, CRYPTO_MAX_ALG_NAME,
+				     "pkcs1pad(%s)",
+				     pkey->pkey_algo);
+		else
+			n = snprintf(alg_name, CRYPTO_MAX_ALG_NAME,
+				     "pkcs1pad(%s,%s)",
+				     pkey->pkey_algo, hash_algo);
+		return n >= CRYPTO_MAX_ALG_NAME ? -EINVAL : 0;
+	}
+
+	if (strcmp(encoding, "raw") == 0) {
+		strcpy(alg_name, pkey->pkey_algo);
+		return 0;
+	}
+
+	return -ENOPKG;
+}
+
+static u8 *pkey_pack_u32(u8 *dst, u32 val)
+{
+	memcpy(dst, &val, sizeof(val));
+	return dst + sizeof(val);
+}
+
+/*
+ * Query information about a key.
+ */
+static int software_key_query(const struct kernel_pkey_params *params,
+			      struct kernel_pkey_query *info)
+{
+	struct crypto_akcipher *tfm;
+	struct public_key *pkey = params->key->payload.data[asym_crypto];
+	char alg_name[CRYPTO_MAX_ALG_NAME];
+	u8 *key, *ptr;
+	int ret, len;
+
+	ret = software_key_determine_akcipher(params->encoding,
+					      params->hash_algo,
+					      pkey, alg_name);
+	if (ret < 0)
+		return ret;
+
+	tfm = crypto_alloc_akcipher(alg_name, 0, 0);
+	if (IS_ERR(tfm))
+		return PTR_ERR(tfm);
+
+	key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
+		      GFP_KERNEL);
+	if (!key)
+		goto error_free_tfm;
+	memcpy(key, pkey->key, pkey->keylen);
+	ptr = key + pkey->keylen;
+	ptr = pkey_pack_u32(ptr, pkey->algo);
+	ptr = pkey_pack_u32(ptr, pkey->paramlen);
+	memcpy(ptr, pkey->params, pkey->paramlen);
+
+	if (pkey->key_is_private)
+		ret = crypto_akcipher_set_priv_key(tfm, key, pkey->keylen);
+	else
+		ret = crypto_akcipher_set_pub_key(tfm, key, pkey->keylen);
+	if (ret < 0)
+		goto error_free_key;
+
+	len = crypto_akcipher_maxsize(tfm);
+	info->key_size = len * 8;
+	info->max_data_size = len;
+	info->max_sig_size = len;
+	info->max_enc_size = len;
+	info->max_dec_size = len;
+	info->supported_ops = (KEYCTL_SUPPORTS_ENCRYPT |
+			       KEYCTL_SUPPORTS_VERIFY);
+	if (pkey->key_is_private)
+		info->supported_ops |= (KEYCTL_SUPPORTS_DECRYPT |
+					KEYCTL_SUPPORTS_SIGN);
+	ret = 0;
+
+error_free_key:
+	kfree(key);
+error_free_tfm:
+	crypto_free_akcipher(tfm);
+	pr_devel("<==%s() = %d\n", __func__, ret);
+	return ret;
+}
+
+/*
+ * Do encryption, decryption and signing ops.
+ */
+static int software_key_eds_op(struct kernel_pkey_params *params,
+			       const void *in, void *out)
+{
+	const struct public_key *pkey = params->key->payload.data[asym_crypto];
+	struct akcipher_request *req;
+	struct crypto_akcipher *tfm;
+	struct crypto_wait cwait;
+	struct scatterlist in_sg, out_sg;
+	char alg_name[CRYPTO_MAX_ALG_NAME];
+	char *key, *ptr;
+	int ret;
+
+	pr_devel("==>%s()\n", __func__);
+
+	ret = software_key_determine_akcipher(params->encoding,
+					      params->hash_algo,
+					      pkey, alg_name);
+	if (ret < 0)
+		return ret;
+
+	tfm = crypto_alloc_akcipher(alg_name, 0, 0);
+	if (IS_ERR(tfm))
+		return PTR_ERR(tfm);
+
+	req = akcipher_request_alloc(tfm, GFP_KERNEL);
+	if (!req)
+		goto error_free_tfm;
+
+	key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
+		      GFP_KERNEL);
+	if (!key)
+		goto error_free_req;
+
+	memcpy(key, pkey->key, pkey->keylen);
+	ptr = key + pkey->keylen;
+	ptr = pkey_pack_u32(ptr, pkey->algo);
+	ptr = pkey_pack_u32(ptr, pkey->paramlen);
+	memcpy(ptr, pkey->params, pkey->paramlen);
+
+	if (pkey->key_is_private)
+		ret = crypto_akcipher_set_priv_key(tfm, key, pkey->keylen);
+	else
+		ret = crypto_akcipher_set_pub_key(tfm, key, pkey->keylen);
+	if (ret)
+		goto error_free_key;
+
+	sg_init_one(&in_sg, in, params->in_len);
+	sg_init_one(&out_sg, out, params->out_len);
+	akcipher_request_set_crypt(req, &in_sg, &out_sg, params->in_len,
+				   params->out_len);
+	crypto_init_wait(&cwait);
+	akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
+				      CRYPTO_TFM_REQ_MAY_SLEEP,
+				      crypto_req_done, &cwait);
+
+	/* Perform the encryption calculation. */
+	switch (params->op) {
+	case kernel_pkey_encrypt:
+		ret = crypto_akcipher_encrypt(req);
+		break;
+	case kernel_pkey_decrypt:
+		ret = crypto_akcipher_decrypt(req);
+		break;
+	case kernel_pkey_sign:
+		ret = crypto_akcipher_sign(req);
+		break;
+	default:
+		BUG();
+	}
+
+	ret = crypto_wait_req(ret, &cwait);
+	if (ret == 0)
+		ret = req->dst_len;
+
+error_free_key:
+	kfree(key);
+error_free_req:
+	akcipher_request_free(req);
+error_free_tfm:
+	crypto_free_akcipher(tfm);
+	pr_devel("<==%s() = %d\n", __func__, ret);
+	return ret;
+}
+
+/*
+ * Verify a signature using a public key.
+ */
+int public_key_verify_signature(const struct public_key *pkey,
+				const struct public_key_signature *sig)
+{
+	struct crypto_wait cwait;
+	struct crypto_akcipher *tfm;
+	struct akcipher_request *req;
+	struct scatterlist src_sg[2];
+	char alg_name[CRYPTO_MAX_ALG_NAME];
+	char *key, *ptr;
+	int ret;
+
+	pr_devel("==>%s()\n", __func__);
+
+	BUG_ON(!pkey);
+	BUG_ON(!sig);
+	BUG_ON(!sig->s);
+
+	ret = software_key_determine_akcipher(sig->encoding,
+					      sig->hash_algo,
+					      pkey, alg_name);
+	if (ret < 0)
+		return ret;
+
+	tfm = crypto_alloc_akcipher(alg_name, 0, 0);
+	if (IS_ERR(tfm))
+		return PTR_ERR(tfm);
+
+	ret = -ENOMEM;
+	req = akcipher_request_alloc(tfm, GFP_KERNEL);
+	if (!req)
+		goto error_free_tfm;
+
+	key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
+		      GFP_KERNEL);
+	if (!key)
+		goto error_free_req;
+
+	memcpy(key, pkey->key, pkey->keylen);
+	ptr = key + pkey->keylen;
+	ptr = pkey_pack_u32(ptr, pkey->algo);
+	ptr = pkey_pack_u32(ptr, pkey->paramlen);
+	memcpy(ptr, pkey->params, pkey->paramlen);
+
+	if (pkey->key_is_private)
+		ret = crypto_akcipher_set_priv_key(tfm, key, pkey->keylen);
+	else
+		ret = crypto_akcipher_set_pub_key(tfm, key, pkey->keylen);
+	if (ret)
+		goto error_free_key;
+
+	sg_init_table(src_sg, 2);
+	sg_set_buf(&src_sg[0], sig->s, sig->s_size);
+	sg_set_buf(&src_sg[1], sig->digest, sig->digest_size);
+	akcipher_request_set_crypt(req, src_sg, NULL, sig->s_size,
+				   sig->digest_size);
+	crypto_init_wait(&cwait);
+	akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
+				      CRYPTO_TFM_REQ_MAY_SLEEP,
+				      crypto_req_done, &cwait);
+	ret = crypto_wait_req(crypto_akcipher_verify(req), &cwait);
+
+error_free_key:
+	kfree(key);
+error_free_req:
+	akcipher_request_free(req);
+error_free_tfm:
+	crypto_free_akcipher(tfm);
+	pr_devel("<==%s() = %d\n", __func__, ret);
+	if (WARN_ON_ONCE(ret > 0))
+		ret = -EINVAL;
+	return ret;
+}
+EXPORT_SYMBOL_GPL(public_key_verify_signature);
+
+static int public_key_verify_signature_2(const struct key *key,
+					 const struct public_key_signature *sig)
+{
+	const struct public_key *pk = key->payload.data[asym_crypto];
+	return public_key_verify_signature(pk, sig);
+}
+
+/*
+ * Public key algorithm asymmetric key subtype
+ */
+struct asymmetric_key_subtype public_key_subtype = {
+	.owner			= THIS_MODULE,
+	.name			= "public_key",
+	.name_len		= sizeof("public_key") - 1,
+	.describe		= public_key_describe,
+	.destroy		= public_key_destroy,
+	.query			= software_key_query,
+	.eds_op			= software_key_eds_op,
+	.verify_signature	= public_key_verify_signature_2,
+};
+EXPORT_SYMBOL_GPL(public_key_subtype);
+#endif /* !__UBOOT__ */