Messages in this thread Patch in this message | | | From | David Howells <> | Subject | [PATCH 16/25] KEYS: Provide a function to load keys from a PGP keyring blob | Date | Thu, 16 Aug 2012 02:37:08 +0100 |
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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@I-love.SAKURA.ne.jp> for some pointing out some errors.
Signed-off-by: David Howells <dhowells@redhat.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@redhat.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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