From: David Howells <dhowells@xxxxxxxxxx>
Implement a PGP data parser for the crypto key type to use when
instantiating a key.
This parser attempts to parse the instantiation data as a PGP packet
sequence (RFC 4880) and if it parses okay, attempts to extract a public-key
algorithm key or subkey from it.
If it finds such a key, it will set up a public_key subtype payload with
appropriate handler routines (DSA or RSA) and attach it to the key.
Thanks to Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> for pointing
out some errors.
Changelog
v0:
- remove declaration of pgp_to_public_key_algo (Roberto Sassu)
- replace prep->type_data with prep->payload.data (Roberto Sassu)
- replace public_key_destroy() with public_key_free() (Roberto Sassu)
- use asymmetric_key_generate_id() to generate the key identifiers
(Roberto Sassu)
- add raw_fingerprint to pgp_key_data_parse_context structure
(Roberto Sassu)
- replace algorithm identifiers with strings (Roberto Sassu)
- don't parse MPIs (Roberto Sassu)
- don't process Public-Subkey packets (only one key will be created)
(Roberto Sassu)
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Co-developed-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
---
crypto/asymmetric_keys/Kconfig | 11 +
crypto/asymmetric_keys/Makefile | 4 +
crypto/asymmetric_keys/pgp_public_key.c | 336 ++++++++++++++++++++++++
3 files changed, 351 insertions(+)
create mode 100644 crypto/asymmetric_keys/pgp_public_key.c
diff --git a/crypto/asymmetric_keys/Kconfig b/crypto/asymmetric_keys/Kconfig
index 38c36c14d712..356b85fc34bd 100644
--- a/crypto/asymmetric_keys/Kconfig
+++ b/crypto/asymmetric_keys/Kconfig
@@ -99,4 +99,15 @@ config PGP_LIBRARY
This option enables a library that provides a number of simple
utility functions for parsing PGP (RFC 4880) packet-based messages.
+config PGP_KEY_PARSER
+ tristate "PGP key parser"
+ depends on ASYMMETRIC_PUBLIC_KEY_SUBTYPE
+ select PGP_LIBRARY
+ select MD5 # V3 fingerprint generation
+ select SHA1 # V4 fingerprint generation
+ help
+ 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.
+
endif # ASYMMETRIC_KEY_TYPE
diff --git a/crypto/asymmetric_keys/Makefile b/crypto/asymmetric_keys/Makefile
index 55a67ebfe8e1..a68f9a5d1746 100644
--- a/crypto/asymmetric_keys/Makefile
+++ b/crypto/asymmetric_keys/Makefile
@@ -91,3 +91,7 @@ $(obj)/tpm.asn1.o: $(obj)/tpm.asn1.c $(obj)/tpm.asn1.h
# PGP handling
#
obj-$(CONFIG_PGP_LIBRARY) += pgp_library.o
+
+obj-$(CONFIG_PGP_KEY_PARSER) += pgp_key_parser.o
+pgp_key_parser-y := \
+ pgp_public_key.o
diff --git a/crypto/asymmetric_keys/pgp_public_key.c b/crypto/asymmetric_keys/pgp_public_key.c
new file mode 100644
index 000000000000..a5ce146a1250
--- /dev/null
+++ b/crypto/asymmetric_keys/pgp_public_key.c
@@ -0,0 +1,336 @@
+/* Instantiate a public key crypto key from PGP format data [RFC 4880]
+ *
+ * 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 pr_fmt(fmt) "PGP: "fmt
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/mpi.h>
+#include <linux/pgplib.h>
+#include <keys/asymmetric-subtype.h>
+#include <keys/asymmetric-parser.h>
+#include <crypto/hash.h>
+#include <crypto/public_key.h>
+#include "pgp_parser.h"
+
+#define MAX_MPI 5
+
+MODULE_LICENSE("GPL");
+
+static inline void digest_putc(struct shash_desc *digest, uint8_t ch)
+{
+ crypto_shash_update(digest, &ch, 1);
+}
+
+struct pgp_key_data_parse_context {
+ struct pgp_parse_context pgp;
+ struct public_key *pub;
+ unsigned char *raw_fingerprint;
+ char *fingerprint;
+};
+
+/*
+ * Calculate the public key ID (RFC4880 12.2)
+ */
+static int pgp_calc_pkey_keyid(struct shash_desc *digest,
+ struct pgp_parse_pubkey *pgp,
+ struct public_key *pub)
+{
+ unsigned int nb[MAX_MPI];
+ unsigned int nn[MAX_MPI];
+ unsigned int n;
+ size_t keylen = pub->keylen;
+ u8 *key_ptr = pub->key;
+ u8 *pp[MAX_MPI];
+ u32 a32;
+ int npkey;
+ int i, ret;
+
+ kenter("");
+
+ n = (pgp->version < PGP_KEY_VERSION_4) ? 8 : 6;
+ for (i = 0; i < MAX_MPI && keylen > 0; i++) {
+ ret = mpi_key_length(key_ptr, keylen, nb + i, nn + i);
+ if (ret < 0)
+ return ret;
+
+ pp[i] = key_ptr + 2;
+ key_ptr += 2 + nn[i];
+ keylen -= 2 + nn[i];
+ n += 2 + nn[i];
+ }
+
+ if (keylen != 0) {
+ pr_debug("excess %zu\n", keylen);
+ return -EBADMSG;
+ }
+
+ npkey = i;
+
+ digest_putc(digest, 0x99); /* ctb */
+ digest_putc(digest, n >> 8); /* 16-bit header length */
+ digest_putc(digest, n);
+ digest_putc(digest, pgp->version);
+
+ a32 = pgp->creation_time;
+ digest_putc(digest, a32 >> 24);
+ digest_putc(digest, a32 >> 16);
+ digest_putc(digest, a32 >> 8);
+ digest_putc(digest, a32 >> 0);
+
+ if (pgp->version < PGP_KEY_VERSION_4) {
+ u16 a16;
+
+ if (pgp->expires_at)
+ a16 = (pgp->expires_at - pgp->creation_time) / 86400UL;
+ else
+ a16 = 0;
+ digest_putc(digest, a16 >> 8);
+ digest_putc(digest, a16 >> 0);
+ }
+
+ digest_putc(digest, pgp->pubkey_algo);
+
+ 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]);
+ }
+ ret = 0;
+
+ kleave(" = %d", ret);
+ return ret;
+}
+
+/*
+ * Calculate the public key ID fingerprint
+ */
+static int pgp_generate_fingerprint(struct pgp_key_data_parse_context *ctx,
+ struct pgp_parse_pubkey *pgp,
+ struct public_key *pub)
+{
+ struct crypto_shash *tfm;
+ struct shash_desc *digest;
+ char *fingerprint;
+ u8 *raw_fingerprint;
+ int digest_size, offset;
+ int ret, i;
+
+ ret = -ENOMEM;
+ tfm = crypto_alloc_shash(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;
+
+ ret = pgp_calc_pkey_keyid(digest, pgp, pub);
+ if (ret < 0)
+ goto cleanup_hash;
+
+ 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;
+ pr_debug("offset %u/%u\n", offset, digest_size);
+
+ for (i = 0; i < digest_size; i++)
+ sprintf(fingerprint + i * 2, "%02x", raw_fingerprint[i]);
+ pr_debug("fingerprint %s\n", fingerprint);
+
+ ctx->raw_fingerprint = raw_fingerprint;
+ ctx->fingerprint = fingerprint;
+ ret = 0;
+cleanup_raw_fingerprint:
+ if (ret < 0)
+ kfree(raw_fingerprint);
+cleanup_hash:
+ kfree(digest);
+cleanup_tfm:
+ crypto_free_shash(tfm);
+cleanup:
+ kleave(" = %d", ret);
+ return ret;
+}
+
+/*
+ * Extract a public key or public subkey from the PGP stream.
+ */
+static int pgp_process_public_key(struct pgp_parse_context *context,
+ enum pgp_packet_tag type,
+ u8 headerlen,
+ const u8 *data,
+ size_t datalen)
+{
+ const char *algo;
+ struct pgp_key_data_parse_context *ctx =
+ container_of(context, struct pgp_key_data_parse_context, pgp);
+ struct pgp_parse_pubkey pgp;
+ struct public_key *pub;
+ int ret;
+
+ kenter(",%u,%u,,%zu", type, headerlen, datalen);
+
+ if (ctx->fingerprint) {
+ kleave(" = -ENOKEY [already]");
+ return -EBADMSG;
+ }
+
+ pub = kzalloc(sizeof(struct public_key), GFP_KERNEL);
+ if (!pub)
+ return -ENOMEM;
+ pub->id_type = "PGP";
+
+ ret = pgp_parse_public_key(&data, &datalen, &pgp);
+ if (ret < 0)
+ goto cleanup;
+
+ if (pgp.pubkey_algo >= PGP_PUBKEY__LAST)
+ goto cleanup_unsupported_pkey_algo;
+ algo = pgp_to_public_key_algo[pgp.pubkey_algo];
+ if (!algo)
+ goto cleanup_unsupported_pkey_algo;
+ pub->pkey_algo = algo;
+
+ pub->key = kmemdup(data, datalen, GFP_KERNEL);
+ if (!pub->key)
+ goto cleanup_nomem;
+
+ pub->keylen = datalen;
+
+ ret = pgp_generate_fingerprint(ctx, &pgp, pub);
+ if (ret < 0)
+ goto cleanup;
+
+ ctx->pub = pub;
+ kleave(" = 0 [use]");
+ return 0;
+
+cleanup_unsupported_pkey_algo:
+ pr_debug("Unsupported public key algorithm %u\n",
+ pgp.pubkey_algo);
+ ret = -ENOPKG;
+ goto cleanup;
+cleanup_nomem:
+ ret = -ENOMEM;
+ goto cleanup;
+cleanup:
+ pr_devel("cleanup");
+ kfree(pub->key);
+ kfree(pub);
+ kleave(" = %d", ret);
+ return ret;
+}
+
+static struct asymmetric_key_ids *pgp_key_generate_id(
+ struct pgp_key_data_parse_context *ctx)
+{
+ struct asymmetric_key_ids *kids;
+ struct asymmetric_key_id *kid;
+ int fingerprint_len = strlen(ctx->fingerprint) / 2;
+
+ kids = kzalloc(sizeof(struct asymmetric_key_ids), GFP_KERNEL);
+ if (!kids)
+ return kids;
+
+ kid = asymmetric_key_generate_id(ctx->raw_fingerprint, fingerprint_len,
+ NULL, 0);
+ if (IS_ERR(kid))
+ goto error;
+
+ kids->id[0] = kid;
+ kids->id[1] = kmemdup(kid, sizeof(kid) + fingerprint_len, GFP_KERNEL);
+ if (!kids->id[1])
+ goto error;
+
+ return kids;
+error:
+ kfree(kids->id[0]);
+ kfree(kids);
+
+ return NULL;
+}
+
+/*
+ * Attempt to parse the instantiation data blob for a key as a PGP packet
+ * message holding a key.
+ */
+static int pgp_key_parse(struct key_preparsed_payload *prep)
+{
+ struct pgp_key_data_parse_context ctx;
+ int ret;
+
+ kenter("");
+
+ memset(&ctx, 0, sizeof(ctx));
+ ctx.pgp.types_of_interest = (1 << PGP_PKT_PUBLIC_KEY);
+ ctx.pgp.process_packet = pgp_process_public_key;
+
+ ret = pgp_parse_packets(prep->data, prep->datalen, &ctx.pgp);
+ if (ret < 0)
+ goto error;
+
+ /* We're pinning the module by being linked against it */
+ __module_get(public_key_subtype.owner);
+ prep->payload.data[asym_subtype] = &public_key_subtype;
+ prep->payload.data[asym_key_ids] = pgp_key_generate_id(&ctx);
+ prep->payload.data[asym_crypto] = ctx.pub;
+ prep->quotalen = 100;
+ return 0;
+
+error:
+ public_key_free(ctx.pub);
+ kfree(ctx.fingerprint);
+ kfree(ctx.raw_fingerprint);
+ return ret;
+}
+
+static struct asymmetric_key_parser pgp_key_parser = {
+ .owner = THIS_MODULE,
+ .name = "pgp",
+ .parse = pgp_key_parse,
+};
+
+/*
+ * Module stuff
+ */
+static int __init pgp_key_init(void)
+{
+ return register_asymmetric_key_parser(&pgp_key_parser);
+}
+
+static void __exit pgp_key_exit(void)
+{
+ unregister_asymmetric_key_parser(&pgp_key_parser);
+}
+
+module_init(pgp_key_init);
+module_exit(pgp_key_exit);
--
2.17.1
