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Message-ID: <20120816013708.872.22387.stgit@warthog.procyon.org.uk>
Date: Thu, 16 Aug 2012 02:37:08 +0100
From: David Howells <dhowells@...hat.com>
To: rusty@...tcorp.com.au
Cc: dhowells@...hat.com, dmitry.kasatkin@...el.com,
zohar@...ux.vnet.ibm.com, jmorris@...ei.org,
keyrings@...ux-nfs.org, linux-security-module@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH 16/25] KEYS: Provide a function to load keys from a PGP
keyring blob
Provide a function to load keys from a PGP keyring blob for use in initialising
the module signing key keyring:
int load_PGP_keys(const u8 *pgpdata, size_t pgpdatalen,
struct key *keyring, const char *descprefix);
The keys are labelled with descprefix plus a number to uniquify them. The keys
will actually be identified by the ID calculated from the PGP data rather than
by the description, so this shouldn't be a problem.
The keys are attached to the keyring supplied.
Looking as root in /proc/keys after the module signing keyring has been loaded:
24460d1c I----- 1 perm 3f010000 0 0 crypto modsign.0: dsa 5acc2142 []
3ca85723 I----- 1 perm 1f010000 0 0 keyring .module_sign: 1/4
Thanks to Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp> for some pointing
out some errors.
Signed-off-by: David Howells <dhowells@...hat.com>
---
Documentation/security/keys-crypto.txt | 20 ++++++
include/keys/crypto-type.h | 3 +
security/keys/crypto/Kconfig | 9 +++
security/keys/crypto/Makefile | 1
security/keys/crypto/pgp_preload.c | 115 ++++++++++++++++++++++++++++++++
5 files changed, 148 insertions(+)
create mode 100644 security/keys/crypto/pgp_preload.c
diff --git a/Documentation/security/keys-crypto.txt b/Documentation/security/keys-crypto.txt
index 0a886ec..be5067e 100644
--- a/Documentation/security/keys-crypto.txt
+++ b/Documentation/security/keys-crypto.txt
@@ -10,6 +10,7 @@ Contents:
- Signature verification.
- Implementing crypto parsers.
- Implementing crypto subtypes.
+ - Initial PGP key preloading.
========
@@ -279,3 +280,22 @@ There are a number of operations defined by the subtype:
Mandatory. This should free the memory associated with the key. The
crypto key will look after freeing the fingerprint and releasing the
reference on the subtype module.
+
+
+=======================
+INITIAL PGP KEY LOADING
+=======================
+
+A function is provided to perform an initial load of a set of public keys bound
+into a PGP packet format blob:
+
+ int preload_pgp_keys(const u8 *pgpdata, size_t pgpdatalen,
+ struct key *keyring);
+
+This takes the blob of data defined by pgpdata and pgpdatalen, extracts keys
+from them and adds them to the specified keyring. The keys are labelled with a
+description generated from the fingerprint and last user ID of each key. The
+description is required to prevent all but the last key being discarded when
+the keys are linked into the keyring.
+
+This function is only available during initial kernel set up.
diff --git a/include/keys/crypto-type.h b/include/keys/crypto-type.h
index 0fb362a..ed9b203 100644
--- a/include/keys/crypto-type.h
+++ b/include/keys/crypto-type.h
@@ -31,4 +31,7 @@ extern void verify_sig_cancel(struct crypto_sig_verify_context *ctx);
* The payload is at the discretion of the subtype.
*/
+extern __init int preload_pgp_keys(const u8 *pgpdata, size_t pgpdatalen,
+ struct key *keyring);
+
#endif /* _KEYS_CRYPTO_TYPE_H */
diff --git a/security/keys/crypto/Kconfig b/security/keys/crypto/Kconfig
index 1c2ae55..8af0155 100644
--- a/security/keys/crypto/Kconfig
+++ b/security/keys/crypto/Kconfig
@@ -40,3 +40,12 @@ config CRYPTO_KEY_PGP_PARSER
This option provides support for parsing PGP (RFC 4880) format blobs
for key data and provides the ability to instantiate a crypto key
from a public key packet found inside the blob.
+
+config PGP_PRELOAD
+ bool "PGP public key preloading facility"
+ select PGP_LIBRARY
+ select CRYPTO_KEY_PGP_PARSER
+ help
+ This option provides a facility for the kernel to preload PGP-wrapped
+ bundles of keys during boot. It is used by module signing to load
+ the module signing keys for example.
diff --git a/security/keys/crypto/Makefile b/security/keys/crypto/Makefile
index a9a34c6..c873674 100644
--- a/security/keys/crypto/Makefile
+++ b/security/keys/crypto/Makefile
@@ -8,6 +8,7 @@ crypto_keys-y := crypto_type.o crypto_verify.o
obj-$(CONFIG_CRYPTO_KEY_PUBLIC_KEY_SUBTYPE) += public_key.o
obj-$(CONFIG_CRYPTO_KEY_PKEY_ALGO_RSA) += crypto_rsa.o
obj-$(CONFIG_PGP_LIBRARY) += pgp_library.o
+obj-$(CONFIG_PGP_PRELOAD) += pgp_preload.o
obj-$(CONFIG_CRYPTO_KEY_PGP_PARSER) += pgp_key_parser.o
pgp_key_parser-y := \
diff --git a/security/keys/crypto/pgp_preload.c b/security/keys/crypto/pgp_preload.c
new file mode 100644
index 0000000..ca4cfe6
--- /dev/null
+++ b/security/keys/crypto/pgp_preload.c
@@ -0,0 +1,115 @@
+/* Cryptographic key request handling
+ *
+ * Copyright (C) 2011 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@...hat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ *
+ * See Documentation/security/keys-crypto.txt
+ */
+
+#include <linux/module.h>
+#include <linux/key.h>
+#include <linux/pgplib.h>
+#include <linux/err.h>
+#include <keys/crypto-type.h>
+#include "crypto_keys.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 int __init create_pgp_key(struct preload_pgp_keys_context *ctx)
+{
+ key_ref_t key;
+
+ key = key_create_or_update(ctx->keyring, "crypto", NULL,
+ ctx->key_start,
+ ctx->key_end - ctx->key_start,
+ KEY_POS_ALL | KEY_USR_VIEW,
+ KEY_ALLOC_NOT_IN_QUOTA);
+ if (IS_ERR(key))
+ return PTR_ERR(key);
+
+ pr_notice("Loaded %s key: %s\n",
+ key_ref_to_ptr(key)->description,
+ crypto_key_id(key_ref_to_ptr(key)));
+
+ key_ref_put(key);
+ return 0;
+}
+
+/*
+ * 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);
+ int ret;
+
+ if (ctx->found_key) {
+ ctx->key_end = data - headerlen;
+ ret = create_pgp_key(ctx);
+ if (ret < 0)
+ return ret;
+ }
+
+ 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) | (1 << PGP_PKT_PUBLIC_SUBKEY);
+ 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;
+ return create_pgp_key(&ctx);
+ }
+ return 0;
+}
--
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