[v2,13/14] KEYS: Provide a function to load keys from a PGP keyring blob

diff --git a/crypto/asymmetric_keys/Kconfig b/crypto/asymmetric_keys/Kconfig
index d9c709e042f6..6379efded6f4 100644
--- a/crypto/asymmetric_keys/Kconfig
+++ b/crypto/asymmetric_keys/Kconfig
@@ -133,4 +133,12 @@  config PGP_TEST_KEY
 
 	  This is intended for testing the PGP parser.
 
+config PGP_PRELOAD
+	bool "PGP public key preloading facility"
+	depends on SYSTEM_TRUSTED_KEYRING
+	select PGP_KEY_PARSER
+	help
+	  This option provides a facility for the kernel to preload PGP-wrapped
+	  bundles of keys during boot to the built-in keyring.
+
 endif # ASYMMETRIC_KEY_TYPE
diff --git a/crypto/asymmetric_keys/Makefile b/crypto/asymmetric_keys/Makefile
index 507a78f9a0a1..2fa55a7830e6 100644
--- a/crypto/asymmetric_keys/Makefile
+++ b/crypto/asymmetric_keys/Makefile
@@ -84,6 +84,7 @@  $(obj)/mscode.asn1.o: $(obj)/mscode.asn1.c $(obj)/mscode.asn1.h
 # PGP handling
 #
 obj-$(CONFIG_PGP_LIBRARY) += pgp_library.o
+obj-$(CONFIG_PGP_PRELOAD) += pgp_preload.o
 
 obj-$(CONFIG_PGP_KEY_PARSER) += pgp_key_parser.o
 pgp_key_parser-y := \
diff --git a/crypto/asymmetric_keys/pgp_preload.c b/crypto/asymmetric_keys/pgp_preload.c
new file mode 100644
index 000000000000..e0776dc8f928
--- /dev/null
+++ b/crypto/asymmetric_keys/pgp_preload.c
@@ -0,0 +1,111 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/* Asymmetric key request handling
+ *
+ * Copyright (C) 2011 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#include <linux/module.h>
+#include <linux/key.h>
+#include <linux/err.h>
+#include <crypto/pgp.h>
+#include <keys/asymmetric-type.h>
+
+#include "pgp_parser.h"
+
+struct preload_pgp_keys_context {
+	struct pgp_parse_context pgp;
+	key_ref_t keyring;
+	const u8 *key_start;
+	const u8 *key_end;
+	bool found_key;
+};
+
+/*
+ * Create a key.
+ */
+static void __init create_pgp_key(struct preload_pgp_keys_context *ctx)
+{
+	key_ref_t key;
+
+	key = key_create_or_update(ctx->keyring,
+				   "asymmetric",
+				   NULL,
+				   ctx->key_start,
+				   ctx->key_end - ctx->key_start,
+				   ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
+				    KEY_USR_VIEW | KEY_USR_READ),
+				   KEY_ALLOC_NOT_IN_QUOTA |
+				   KEY_ALLOC_BUILT_IN |
+				   KEY_ALLOC_BYPASS_RESTRICTION);
+	if (IS_ERR(key)) {
+		pr_notice("Ignoring PGP key, error: %ld\n", PTR_ERR(key));
+		return;
+	}
+
+	pr_notice("Loaded PGP key '%s'\n",
+		  key_ref_to_ptr(key)->description);
+
+	key_ref_put(key);
+}
+
+/*
+ * Extract a public key or subkey from the PGP stream.
+ */
+static int __init found_pgp_key(struct pgp_parse_context *context,
+				enum pgp_packet_tag type, u8 headerlen,
+				const u8 *data, size_t datalen)
+{
+	struct preload_pgp_keys_context *ctx =
+		container_of(context, struct preload_pgp_keys_context, pgp);
+
+	if (ctx->found_key) {
+		ctx->key_end = data - headerlen;
+		create_pgp_key(ctx);
+	}
+
+	ctx->key_start = data - headerlen;
+	ctx->found_key = true;
+	return 0;
+}
+
+/**
+ * preload_pgp_keys - Load keys from a PGP keyring blob
+ * @pgpdata: The PGP keyring blob containing the keys.
+ * @pgpdatalen: The size of the @pgpdata blob.
+ * @keyring: The keyring to add the new keys to.
+ *
+ * Preload a pack of keys from a PGP keyring blob.
+ *
+ * The keys have their descriptions generated from the user ID and fingerprint
+ * in the PGP stream.  Since keys can be matched on their key IDs independently
+ * of the key description, the description is mostly irrelevant apart from the
+ * fact that keys of the same description displace one another from a keyring.
+ *
+ * The caller should override the current creds if they want the keys to be
+ * owned by someone other than the current process's owner.  Keys will not be
+ * accounted towards the owner's quota.
+ *
+ * This function may only be called whilst the kernel is booting.
+ */
+int __init preload_pgp_keys(const u8 *pgpdata, size_t pgpdatalen,
+			    struct key *keyring)
+{
+	struct preload_pgp_keys_context ctx;
+	int ret;
+
+	ctx.pgp.types_of_interest = (1 << PGP_PKT_PUBLIC_KEY);
+	ctx.pgp.process_packet = found_pgp_key;
+	ctx.keyring = make_key_ref(keyring, 1);
+	ctx.found_key = false;
+
+	ret = pgp_parse_packets(pgpdata, pgpdatalen, &ctx.pgp);
+	if (ret < 0)
+		return ret;
+
+	if (ctx.found_key) {
+		ctx.key_end = pgpdata + pgpdatalen;
+		create_pgp_key(&ctx);
+	}
+	return 0;
+}
diff --git a/include/crypto/pgp.h b/include/crypto/pgp.h
index 99dd1ab6c1b1..263b44603636 100644
--- a/include/crypto/pgp.h
+++ b/include/crypto/pgp.h
@@ -1,5 +1,5 @@ 
 /* SPDX-License-Identifier: GPL-2.0+ */
-/* PGP signature processing
+/* PGP key and signature processing
  *
  * Copyright (C) 2014 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells (dhowells@redhat.com)
@@ -27,4 +27,10 @@  extern struct public_key_signature *pgp_sig_get_sig(struct pgp_sig_verify *ctx,
 						    bool is_key_sig);
 extern u8 pgp_sig_get_version(struct pgp_sig_verify *ctx);
 
+/*
+ * pgp_preload.c
+ */
+extern int __init preload_pgp_keys(const u8 *pgpdata, size_t pgpdatalen,
+				   struct key *keyring);
+
 #endif /* _CRYPTO_PGP_H */