From: David Howells Subject: [PATCH 17/21] KEYS: PGP format signature parser [ver #3] Date: Fri, 02 Dec 2011 18:46:02 +0000 Message-ID: <20111202184601.21874.7806.stgit@warthog.procyon.org.uk> References: <20111202184229.21874.25782.stgit@warthog.procyon.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Cc: linux-crypto@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, dmitry.kasatkin@intel.com, zohar@linux.vnet.ibm.com, arjan.van.de.ven@intel.com, alan.cox@intel.com, David Howells To: keyrings@linux-nfs.org Return-path: In-Reply-To: <20111202184229.21874.25782.stgit@warthog.procyon.org.uk> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-crypto.vger.kernel.org Implement a signature parser that will attempt to parse a signature blob as a PGP packet format message. If it can, it will find an appropriate crypto key and set the public-key algorithm according to the data in the signature. Signed-off-by: David Howells --- security/keys/Makefile | 1 security/keys/pgp_key_parser.c | 1 security/keys/pgp_parser.h | 6 ++ security/keys/pgp_sig_parser.c | 104 ++++++++++++++++++++++++++++++++++++++++ 4 files changed, 112 insertions(+), 0 deletions(-) create mode 100644 security/keys/pgp_sig_parser.c diff --git a/security/keys/Makefile b/security/keys/Makefile index fc1968e..c7fa7ea 100644 --- a/security/keys/Makefile +++ b/security/keys/Makefile @@ -35,4 +35,5 @@ crypto_keys-y := crypto_type.o crypto_verify.o pgp_parser-y := \ pgp_key_parser.o \ + pgp_sig_parser.o \ pgp_pubkey_sig.o diff --git a/security/keys/pgp_key_parser.c b/security/keys/pgp_key_parser.c index d0d8a86..12a7644 100644 --- a/security/keys/pgp_key_parser.c +++ b/security/keys/pgp_key_parser.c @@ -323,6 +323,7 @@ static struct crypto_key_parser pgp_key_parser = { .owner = THIS_MODULE, .name = "pgp", .instantiate = pgp_key_instantiate, + .verify_sig_begin = pgp_verify_sig_begin, }; /* diff --git a/security/keys/pgp_parser.h b/security/keys/pgp_parser.h index a6192ce..73c900e 100644 --- a/security/keys/pgp_parser.h +++ b/security/keys/pgp_parser.h @@ -23,6 +23,12 @@ extern const struct public_key_algorithm *pgp_public_key_algorithms[PGP_PUBKEY__LAST]; /* + * pgp_sig_parser.c + */ +extern struct crypto_key_verify_context *pgp_verify_sig_begin( + struct key *keyring, const u8 *sig, size_t siglen); + +/* * pgp_pubkey_sig.c */ extern struct crypto_key_verify_context *pgp_pkey_verify_sig_begin( diff --git a/security/keys/pgp_sig_parser.c b/security/keys/pgp_sig_parser.c new file mode 100644 index 0000000..b72c505 --- /dev/null +++ b/security/keys/pgp_sig_parser.c @@ -0,0 +1,104 @@ +/* Handling for PGP public key signature data [RFC 4880] + * + * 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. + */ + +#define pr_fmt(fmt) "PGPSIG: "fmt +#include +#include +#include +#include "public_key.h" +#include "pgp_parser.h" + +struct PGP_sig_parse_context { + struct pgp_parse_context pgp; + struct pgp_sig_parameters params; + bool found_sig; +}; + +/* + * Look inside signature sections for a key ID + */ +static int pgp_process_signature(struct pgp_parse_context *context, + enum pgp_packet_tag type, + u8 headerlen, + const u8 *data, + size_t datalen) +{ + struct PGP_sig_parse_context *ctx = + container_of(context, struct PGP_sig_parse_context, pgp); + + ctx->found_sig = true; + return pgp_parse_sig_params(&data, &datalen, &ctx->params); +} + +/* + * Attempt to find a key to use for PGP signature verification, starting off by + * looking in the supplied keyring. + * + * The function may also look for other key sources such as a TPM. If an + * alternative key is found it can be added to the keyring for future + * reference. + */ +static struct key *find_key_for_pgp_sig(struct key *keyring, + const u8 *sig, size_t siglen) +{ + struct PGP_sig_parse_context p; + key_ref_t key; + char criterion[3 + 8 * 2 + 1]; + int ret; + + if (!keyring) + return ERR_PTR(-ENOKEY); + + /* Need to find the key ID */ + p.pgp.types_of_interest = (1 << PGP_PKT_SIGNATURE); + p.pgp.process_packet = pgp_process_signature; + p.found_sig = false; + ret = pgp_parse_packets(sig, siglen, &p.pgp); + if (ret < 0) + return ERR_PTR(ret); + + if (!p.found_sig) + return ERR_PTR(-EINVAL); + + sprintf(criterion, "id:%08x%08x", + be32_to_cpu(p.params.issuer32[0]), + be32_to_cpu(p.params.issuer32[1])); + + pr_debug("Look up: %s\n", criterion); + + key = keyring_search(make_key_ref(keyring, 1), + &key_type_crypto, criterion); + if (IS_ERR(key)) + return ERR_CAST(key); + + pr_debug("Found key %x\n", key_serial(key_ref_to_ptr(key))); + return key_ref_to_ptr(key); +} + +/* + * Attempt to parse a signature as a PGP packet format blob and find a + * matching key. + */ +struct crypto_key_verify_context *pgp_verify_sig_begin( + struct key *keyring, const u8 *sig, size_t siglen) +{ + struct crypto_key_verify_context *ctx; + struct key *key; + + key = find_key_for_pgp_sig(keyring, sig, siglen); + if (IS_ERR(key)) + return ERR_CAST(key); + + /* We only handle in-kernel public key signatures for the moment */ + ctx = pgp_pkey_verify_sig_begin(key, sig, siglen); + key_put(key); + return ctx; +}