From: David Howells Subject: [PATCH 05/14] KEYS: Add a DSA crypto key subtype Date: Mon, 28 Nov 2011 15:45:26 +0000 Message-ID: <20111128154526.6009.22566.stgit@warthog.procyon.org.uk> References: <20111128154436.6009.77586.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, mitry.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: <20111128154436.6009.77586.stgit@warthog.procyon.org.uk> Sender: linux-security-module-owner@vger.kernel.org List-Id: linux-crypto.vger.kernel.org Add a key subtype for handling DSA crypto keys. For the moment it only provides a signature verification facility. Signed-off-by: David Howells --- security/Kconfig | 10 + security/keys/Makefile | 2 security/keys/crypto_dsa.h | 36 ++++ security/keys/crypto_dsa_subtype.c | 338 ++++++++++++++++++++++++++++++++++++ 4 files changed, 386 insertions(+), 0 deletions(-) create mode 100644 security/keys/crypto_dsa.h create mode 100644 security/keys/crypto_dsa_subtype.c diff --git a/security/Kconfig b/security/Kconfig index ef39878..48926af 100644 --- a/security/Kconfig +++ b/security/Kconfig @@ -62,6 +62,16 @@ config CRYPTO_KEY_TYPE required for cryptographic operations such as encryption, decryption, signature generation and signature verification. +config CRYPTO_KEY_DSA + tristate "DSA key type" + depends on CRYPTO_KEY_TYPE + select CRYPTO + select MPILIB + select MPILIB_EXTRA + help + This option makes DSA cryptographic keys available. They can be used + for signature verification. + config KEYS_DEBUG_PROC_KEYS bool "Enable the /proc/keys file by which keys may be viewed" depends on KEYS diff --git a/security/keys/Makefile b/security/keys/Makefile index ca85b01..8c499b1 100644 --- a/security/keys/Makefile +++ b/security/keys/Makefile @@ -16,8 +16,10 @@ obj-y := \ obj-$(CONFIG_TRUSTED_KEYS) += trusted.o obj-$(CONFIG_ENCRYPTED_KEYS) += encrypted-keys/ obj-$(CONFIG_CRYPTO_KEY_TYPE) += crypto_keys.o +obj-$(CONFIG_CRYPTO_KEY_DSA) += crypto_dsa.o obj-$(CONFIG_KEYS_COMPAT) += compat.o obj-$(CONFIG_PROC_FS) += proc.o obj-$(CONFIG_SYSCTL) += sysctl.o crypto_keys-y := crypto_type.o pgp_parse.o +crypto_dsa-y := crypto_dsa_subtype.o diff --git a/security/keys/crypto_dsa.h b/security/keys/crypto_dsa.h new file mode 100644 index 0000000..0455634 --- /dev/null +++ b/security/keys/crypto_dsa.h @@ -0,0 +1,36 @@ +/* DSA internal definitions + * + * 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 DSA_NPKEY 4 /* number of MPI's in DSA public key */ + +extern struct crypto_key_subtype DSA_crypto_key_subtype; + +/* + * public key record + */ +struct DSA_public_key { + struct pgp_parse_pubkey pgp; + union { + MPI pkey[DSA_NPKEY]; + struct { + MPI p; /* DSA prime */ + MPI q; /* DSA group order */ + MPI g; /* DSA group generator */ + MPI y; /* DSA public-key value = g^x mod p */ + }; + }; +}; + +struct DSA_payload { + u8 key_id[8]; /* ID of this key pair */ + u8 key_id_size; /* Number of bytes in key_id */ + struct DSA_public_key *public_key; +}; diff --git a/security/keys/crypto_dsa_subtype.c b/security/keys/crypto_dsa_subtype.c new file mode 100644 index 0000000..ae6133b --- /dev/null +++ b/security/keys/crypto_dsa_subtype.c @@ -0,0 +1,338 @@ +/* DSA crypto key subtype + * + * Copyright (C) 2011 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * This file is derived from GnuPG. + * Copyright (C) 1998, 1999, 2000 Free Software Foundation, Inc. + * + * GnuPG is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * GnuPG is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA + */ + +#define DEBUG +#define pr_fmt(fmt) "DSA: "fmt +#include +#include +#include +#include +#include +#include +#include +#define __KDEBUG +#include "internal.h" +#include "crypto_dsa.h" + +MODULE_LICENSE("GPL"); + +static inline void digest_putc(struct shash_desc *digest, uint8_t ch) +{ + crypto_shash_update(digest, &ch, 1); +} + +/* + * Destroy the contents of a DSA payload + */ +static void DSA_destroy_payload(struct DSA_payload *dsa) +{ + int i; + + if (dsa->public_key) { + for (i = 0; i < DSA_NPKEY; i++) + mpi_free(dsa->public_key->pkey[i]); + kfree(dsa->public_key); + } + kfree(dsa); +} + +/* + * Calculate the public key ID (RFC4880 12.2) + */ +static void DSA_calc_pk_keyid(struct shash_desc *digest, + struct DSA_public_key *pk) +{ + unsigned n; + unsigned nb[DSA_NPKEY]; + unsigned nn[DSA_NPKEY]; + u8 *pp[DSA_NPKEY]; + u32 a32; + int i; + int npkey = DSA_NPKEY; + + kenter(""); + + n = (pk->pgp.version < PGP_KEY_VERSION_4) ? 8 : 6; + for (i = 0; i < npkey; i++) { + nb[i] = mpi_get_nbits(pk->pkey[i]); + pp[i] = mpi_get_buffer(pk->pkey[i], nn + i, NULL); + n += 2 + nn[i]; + } + + digest_putc(digest, 0x99); /* ctb */ + digest_putc(digest, n >> 8); /* 16-bit header length */ + digest_putc(digest, n); + digest_putc(digest, pk->pgp.version); + + a32 = pk->pgp.creation_time; + digest_putc(digest, a32 >> 24); + digest_putc(digest, a32 >> 16); + digest_putc(digest, a32 >> 8); + digest_putc(digest, a32 >> 0); + + if (pk->pgp.version < PGP_KEY_VERSION_4) { + u16 a16; + + if( pk->pgp.expires_at) + a16 = (pk->pgp.expires_at - pk->pgp.creation_time) / 86400UL; + else + a16 = 0; + digest_putc(digest, a16 >> 8); + digest_putc(digest, a16 >> 0); + } + + digest_putc(digest, PGP_PUBKEY_DSA); + + for (i = 0; i < npkey; i++) { + digest_putc(digest, nb[i] >> 8); + digest_putc(digest, nb[i]); + crypto_shash_update(digest, pp[i], nn[i]); + kfree(pp[i]); + } + + kleave(""); +} + +/* + * Calculate and check the public key ID fingerprint against the key ID + */ +static int DSA_get_fingerprint(struct DSA_payload *dsa, + struct DSA_public_key *pk, + char **_fingerprint) +{ + struct crypto_shash *tfm; + struct shash_desc *digest; + int digest_size, offset; + char *fingerprint; + u8 *raw_fingerprint; + int ret, i; + + ret = -ENOMEM; + tfm = crypto_alloc_shash(pk->pgp.version < PGP_KEY_VERSION_4 ? + "md5" : "sha1", 0, 0); + if (!tfm) + goto cleanup; + + digest = kmalloc(sizeof(*digest) + crypto_shash_descsize(tfm), + GFP_KERNEL); + if (!digest) + goto cleanup_tfm; + + digest->tfm = tfm; + digest->flags = CRYPTO_TFM_REQ_MAY_SLEEP; + ret = crypto_shash_init(digest); + if (ret < 0) + goto cleanup_hash; + + DSA_calc_pk_keyid(digest, pk); + + digest_size = crypto_shash_digestsize(tfm); + + raw_fingerprint = kmalloc(digest_size, GFP_KERNEL); + if (!raw_fingerprint) + goto cleanup_hash; + + ret = crypto_shash_final(digest, raw_fingerprint); + if (ret < 0) + goto cleanup_raw_fingerprint; + + fingerprint = kmalloc(digest_size * 2 + 1, GFP_KERNEL); + if (!fingerprint) + goto cleanup_raw_fingerprint; + + offset = digest_size - 8; + kdebug("offset %u/%u", offset, digest_size); + + for (i = 0; i < digest_size; i++) + sprintf(fingerprint + i * 2, "%02x", raw_fingerprint[i]); + kdebug("fingerprint %s", fingerprint); + + memcpy(&dsa->key_id, raw_fingerprint + offset, 8); + dsa->key_id_size = 8; + + *_fingerprint = fingerprint; + fingerprint = NULL; + ret = 0; +cleanup_raw_fingerprint: + kfree(raw_fingerprint); +cleanup_hash: + kfree(digest); +cleanup_tfm: + crypto_free_shash(tfm); +cleanup: + kleave(" = %d", ret); + return ret; +} + +struct DSA_pk_parse_context { + struct pgp_parse_context pgp; + struct DSA_payload *dsa; + struct DSA_public_key *pk; + char *fingerprint; +}; + +/* + * Extract a public key or subkey from the PGP stream. + */ +static int DSA_parse_public_key(struct pgp_parse_context *context, + enum pgp_packet_tag type, + u8 headerlen, + const u8 *data, + size_t datalen) +{ + struct DSA_pk_parse_context *ctx = + container_of(context, struct DSA_pk_parse_context, pgp); + struct DSA_payload *dsa = ctx->dsa; + struct DSA_public_key *pk; + int i, ret; + + kenter(",%u,%u,,%zu", type, headerlen, datalen); + + if (dsa->public_key) { + kleave(" = -ENOKEY [already]"); + return -ENOKEY; + } + + pk = kzalloc(sizeof(struct DSA_public_key), GFP_KERNEL); + if (!pk) + return -ENOMEM; + + ret = pgp_parse_public_key(&data, &datalen, &pk->pgp); + if (pk->pgp.pubkey_algo != PGP_PUBKEY_DSA) { + pr_debug("Ignoring non-DSA public key [%u]\n", + pk->pgp.pubkey_algo); + ret = -ENOKEY; + goto cleanup; + } + + ret = -ENOMEM; + for (i = 0; i < DSA_NPKEY; i++) { + unsigned int remaining = datalen; + pk->pkey[i] = mpi_read_from_buffer(data, &remaining); + if (!pk->pkey[i]) + goto cleanup; + data += remaining; + datalen -= remaining; + } + + ret = DSA_get_fingerprint(dsa, pk, &ctx->fingerprint); + if (ret < 0) + goto cleanup; + + dsa->public_key = pk; + kleave(" = 0 [use]"); + return 0; + +cleanup: + kdebug("cleanup"); + if (pk) { + for (i = 0; i < DSA_NPKEY; i++) + mpi_free(pk->pkey[i]); + kfree(pk); + } + kleave(" = %d", ret); + return ret; +} + +/* + * Instantiate a DSA key + */ +static int DSA_instantiate(struct key *key, + const void *data, size_t datalen) +{ + struct DSA_pk_parse_context ctx; + struct DSA_payload *dsa; + int ret; + + kenter(""); + + ret = key_payload_reserve(key, datalen); + if (ret < 0) + return ret; + + dsa = kzalloc(sizeof(struct DSA_payload), GFP_KERNEL); + if (!dsa) + return -ENOMEM; + + ctx.pgp.types_of_interest = + (1 << PGP_PKT_PUBLIC_KEY) | (1 << PGP_PKT_PUBLIC_SUBKEY); + ctx.pgp.process_packet = DSA_parse_public_key; + ctx.dsa = dsa; + ctx.pk = NULL; + ctx.fingerprint = NULL; + + ret = pgp_parse_packets(data, datalen, &ctx.pgp); + if (ret < 0) { + DSA_destroy_payload(dsa); + kfree(ctx.fingerprint); + key_payload_reserve(key, 0); + return ret; + } + + key->type_data.p[0] = &DSA_crypto_key_subtype; + key->type_data.p[1] = ctx.fingerprint; + key->payload.data = dsa; + return 0; +} + +/* + * Destroy a DSA key + */ +static void DSA_destroy(struct key *key) +{ + if (key->payload.data) + DSA_destroy_payload(key->payload.data); +} + +/* + * DSA crypto key subtype + */ +struct crypto_key_subtype DSA_crypto_key_subtype = { + .owner = THIS_MODULE, + .name = "dsa", + .pubkey_algo = PGP_PUBKEY_DSA, + .info = CRYPTO_KEY_IS_PUBKEY_ALGO, + .instantiate = DSA_instantiate, + .destroy = DSA_destroy, + + .verify_sig_begin = DSA_verify_sig_begin, + .verify_sig_add_data = DSA_verify_sig_add_data, + .verify_sig_end = DSA_verify_sig_end, + .verify_sig_cancel = DSA_verify_sig_cancel, +}; + +/* + * Module stuff + */ +static int __init DSA_init(void) +{ + return register_crypto_key_subtype(&DSA_crypto_key_subtype); +} + +static void __exit DSA_cleanup(void) +{ + unregister_crypto_key_subtype(&DSA_crypto_key_subtype); +} + +module_init(DSA_init); +module_exit(DSA_cleanup);