Add a key subtype for handling DSA crypto keys. For the moment it only
provides a signature verification facility.
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
---
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@xxxxxxxxxx)
+ *
+ * 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@xxxxxxxxxx)
+ *
+ * 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 <keys/crypto-subtype.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/mpi.h>
+#include <linux/pgp.h>
+#include <crypto/hash.h>
+#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);
--
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