KEYS: trusted: Add generic trusted keys framework

Current trusted keys framework is tightly coupled to use TPM device as
an underlying implementation which makes it difficult for implementations
like Trusted Execution Environment (TEE) etc. to provide trusted keys
support in case platform doesn't posses a TPM device.

Add a generic trusted keys framework where underlying implementations
can be easily plugged in. Create struct trusted_key_ops to achieve this,
which contains necessary functions of a backend.

Also, define a module parameter in order to select a particular trust
source in case a platform support multiple trust sources. In case its
not specified then implementation itetrates through trust sources list
starting with TPM and assign the first trust source as a backend which
has initiazed successfully during iteration.

Note that current implementation only supports a single trust source at
runtime which is either selectable at compile time or during boot via
aforementioned module parameter.

Suggested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

1 files changed, 69 insertions, 297 deletions

diff --git a/security/keys/trusted-keys/trusted_tpm1.c b/security/keys/trusted-keys/trusted_tpm1.c
index 713b79576840..798dc7820084 100644
--- a/security/keys/trusted-keys/trusted_tpm1.c
+++ b/security/keys/trusted-keys/trusted_tpm1.c
@@ -1,29 +1,22 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (C) 2010 IBM Corporation
- *
- * Author:
- * David Safford <safford@us.ibm.com>
+ * Copyright (c) 2019-2021, Linaro Limited
  *
  * See Documentation/security/keys/trusted-encrypted.rst
  */
 
 #include <crypto/hash_info.h>
-#include <linux/uaccess.h>
-#include <linux/module.h>
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/parser.h>
 #include <linux/string.h>
 #include <linux/err.h>
-#include <keys/user-type.h>
 #include <keys/trusted-type.h>
 #include <linux/key-type.h>
-#include <linux/rcupdate.h>
 #include <linux/crypto.h>
 #include <crypto/hash.h>
 #include <crypto/sha1.h>
-#include <linux/capability.h>
 #include <linux/tpm.h>
 #include <linux/tpm_command.h>
 
@@ -63,7 +56,7 @@ static int TSS_sha1(const unsigned char *data, unsigned int datalen,
 
 	sdesc = init_sdesc(hashalg);
 	if (IS_ERR(sdesc)) {
-		pr_info("trusted_key: can't alloc %s\n", hash_alg);
+		pr_info("can't alloc %s\n", hash_alg);
 		return PTR_ERR(sdesc);
 	}
 
@@ -83,7 +76,7 @@ static int TSS_rawhmac(unsigned char *digest, const unsigned char *key,
 
 	sdesc = init_sdesc(hmacalg);
 	if (IS_ERR(sdesc)) {
-		pr_info("trusted_key: can't alloc %s\n", hmac_alg);
+		pr_info("can't alloc %s\n", hmac_alg);
 		return PTR_ERR(sdesc);
 	}
 
@@ -136,7 +129,7 @@ int TSS_authhmac(unsigned char *digest, const unsigned char *key,
 
 	sdesc = init_sdesc(hashalg);
 	if (IS_ERR(sdesc)) {
-		pr_info("trusted_key: can't alloc %s\n", hash_alg);
+		pr_info("can't alloc %s\n", hash_alg);
 		return PTR_ERR(sdesc);
 	}
 
@@ -212,7 +205,7 @@ int TSS_checkhmac1(unsigned char *buffer,
 
 	sdesc = init_sdesc(hashalg);
 	if (IS_ERR(sdesc)) {
-		pr_info("trusted_key: can't alloc %s\n", hash_alg);
+		pr_info("can't alloc %s\n", hash_alg);
 		return PTR_ERR(sdesc);
 	}
 	ret = crypto_shash_init(&sdesc->shash);
@@ -305,7 +298,7 @@ static int TSS_checkhmac2(unsigned char *buffer,
 
 	sdesc = init_sdesc(hashalg);
 	if (IS_ERR(sdesc)) {
-		pr_info("trusted_key: can't alloc %s\n", hash_alg);
+		pr_info("can't alloc %s\n", hash_alg);
 		return PTR_ERR(sdesc);
 	}
 	ret = crypto_shash_init(&sdesc->shash);
@@ -597,12 +590,12 @@ static int tpm_unseal(struct tpm_buf *tb,
 	/* sessions for unsealing key and data */
 	ret = oiap(tb, &authhandle1, enonce1);
 	if (ret < 0) {
-		pr_info("trusted_key: oiap failed (%d)\n", ret);
+		pr_info("oiap failed (%d)\n", ret);
 		return ret;
 	}
 	ret = oiap(tb, &authhandle2, enonce2);
 	if (ret < 0) {
-		pr_info("trusted_key: oiap failed (%d)\n", ret);
+		pr_info("oiap failed (%d)\n", ret);
 		return ret;
 	}
 
@@ -612,7 +605,7 @@ static int tpm_unseal(struct tpm_buf *tb,
 		return ret;
 
 	if (ret != TPM_NONCE_SIZE) {
-		pr_info("trusted_key: tpm_get_random failed (%d)\n", ret);
+		pr_info("tpm_get_random failed (%d)\n", ret);
 		return -EIO;
 	}
 	ret = TSS_authhmac(authdata1, keyauth, TPM_NONCE_SIZE,
@@ -641,7 +634,7 @@ static int tpm_unseal(struct tpm_buf *tb,
 
 	ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE);
 	if (ret < 0) {
-		pr_info("trusted_key: authhmac failed (%d)\n", ret);
+		pr_info("authhmac failed (%d)\n", ret);
 		return ret;
 	}
 
@@ -653,7 +646,7 @@ static int tpm_unseal(struct tpm_buf *tb,
 			     *datalen, TPM_DATA_OFFSET + sizeof(uint32_t), 0,
 			     0);
 	if (ret < 0) {
-		pr_info("trusted_key: TSS_checkhmac2 failed (%d)\n", ret);
+		pr_info("TSS_checkhmac2 failed (%d)\n", ret);
 		return ret;
 	}
 	memcpy(data, tb->data + TPM_DATA_OFFSET + sizeof(uint32_t), *datalen);
@@ -680,7 +673,7 @@ static int key_seal(struct trusted_key_payload *p,
 		       p->key, p->key_len + 1, p->blob, &p->blob_len,
 		       o->blobauth, o->pcrinfo, o->pcrinfo_len);
 	if (ret < 0)
-		pr_info("trusted_key: srkseal failed (%d)\n", ret);
+		pr_info("srkseal failed (%d)\n", ret);
 
 	tpm_buf_destroy(&tb);
 	return ret;
@@ -702,7 +695,7 @@ static int key_unseal(struct trusted_key_payload *p,
 	ret = tpm_unseal(&tb, o->keyhandle, o->keyauth, p->blob, p->blob_len,
 			 o->blobauth, p->key, &p->key_len);
 	if (ret < 0)
-		pr_info("trusted_key: srkunseal failed (%d)\n", ret);
+		pr_info("srkunseal failed (%d)\n", ret);
 	else
 		/* pull migratable flag out of sealed key */
 		p->migratable = p->key[--p->key_len];
@@ -713,7 +706,6 @@ static int key_unseal(struct trusted_key_payload *p,
 
 enum {
 	Opt_err,
-	Opt_new, Opt_load, Opt_update,
 	Opt_keyhandle, Opt_keyauth, Opt_blobauth,
 	Opt_pcrinfo, Opt_pcrlock, Opt_migratable,
 	Opt_hash,
@@ -722,9 +714,6 @@ enum {
 };
 
 static const match_table_t key_tokens = {
-	{Opt_new, "new"},
-	{Opt_load, "load"},
-	{Opt_update, "update"},
 	{Opt_keyhandle, "keyhandle=%s"},
 	{Opt_keyauth, "keyauth=%s"},
 	{Opt_blobauth, "blobauth=%s"},
@@ -842,7 +831,7 @@ static int getoptions(char *c, struct trusted_key_payload *pay,
 			if (i == HASH_ALGO__LAST)
 				return -EINVAL;
 			if  (!tpm2 && i != HASH_ALGO_SHA1) {
-				pr_info("trusted_key: TPM 1.x only supports SHA-1.\n");
+				pr_info("TPM 1.x only supports SHA-1.\n");
 				return -EINVAL;
 			}
 			break;
@@ -871,71 +860,6 @@ static int getoptions(char *c, struct trusted_key_payload *pay,
 	return 0;
 }
 
-/*
- * datablob_parse - parse the keyctl data and fill in the
- * 		    payload and options structures
- *
- * On success returns 0, otherwise -EINVAL.
- */
-static int datablob_parse(char *datablob, struct trusted_key_payload *p,
-			  struct trusted_key_options *o)
-{
-	substring_t args[MAX_OPT_ARGS];
-	long keylen;
-	int ret = -EINVAL;
-	int key_cmd;
-	char *c;
-
-	/* main command */
-	c = strsep(&datablob, " \t");
-	if (!c)
-		return -EINVAL;
-	key_cmd = match_token(c, key_tokens, args);
-	switch (key_cmd) {
-	case Opt_new:
-		/* first argument is key size */
-		c = strsep(&datablob, " \t");
-		if (!c)
-			return -EINVAL;
-		ret = kstrtol(c, 10, &keylen);
-		if (ret < 0 || keylen < MIN_KEY_SIZE || keylen > MAX_KEY_SIZE)
-			return -EINVAL;
-		p->key_len = keylen;
-		ret = getoptions(datablob, p, o);
-		if (ret < 0)
-			return ret;
-		ret = Opt_new;
-		break;
-	case Opt_load:
-		/* first argument is sealed blob */
-		c = strsep(&datablob, " \t");
-		if (!c)
-			return -EINVAL;
-		p->blob_len = strlen(c) / 2;
-		if (p->blob_len > MAX_BLOB_SIZE)
-			return -EINVAL;
-		ret = hex2bin(p->blob, c, p->blob_len);
-		if (ret < 0)
-			return -EINVAL;
-		ret = getoptions(datablob, p, o);
-		if (ret < 0)
-			return ret;
-		ret = Opt_load;
-		break;
-	case Opt_update:
-		/* all arguments are options */
-		ret = getoptions(datablob, p, o);
-		if (ret < 0)
-			return ret;
-		ret = Opt_update;
-		break;
-	case Opt_err:
-		return -EINVAL;
-		break;
-	}
-	return ret;
-}
-
 static struct trusted_key_options *trusted_options_alloc(void)
 {
 	struct trusted_key_options *options;
@@ -956,252 +880,99 @@ static struct trusted_key_options *trusted_options_alloc(void)
 	return options;
 }
 
-static struct trusted_key_payload *trusted_payload_alloc(struct key *key)
-{
-	struct trusted_key_payload *p = NULL;
-	int ret;
-
-	ret = key_payload_reserve(key, sizeof *p);
-	if (ret < 0)
-		return p;
-	p = kzalloc(sizeof *p, GFP_KERNEL);
-	if (p)
-		p->migratable = 1; /* migratable by default */
-	return p;
-}
-
-/*
- * trusted_instantiate - create a new trusted key
- *
- * Unseal an existing trusted blob or, for a new key, get a
- * random key, then seal and create a trusted key-type key,
- * adding it to the specified keyring.
- *
- * On success, return 0. Otherwise return errno.
- */
-static int trusted_instantiate(struct key *key,
-			       struct key_preparsed_payload *prep)
+static int trusted_tpm_seal(struct trusted_key_payload *p, char *datablob)
 {
-	struct trusted_key_payload *payload = NULL;
 	struct trusted_key_options *options = NULL;
-	size_t datalen = prep->datalen;
-	char *datablob;
 	int ret = 0;
-	int key_cmd;
-	size_t key_len;
 	int tpm2;
 
 	tpm2 = tpm_is_tpm2(chip);
 	if (tpm2 < 0)
 		return tpm2;
 
-	if (datalen <= 0 || datalen > 32767 || !prep->data)
-		return -EINVAL;
-
-	datablob = kmalloc(datalen + 1, GFP_KERNEL);
-	if (!datablob)
-		return -ENOMEM;
-	memcpy(datablob, prep->data, datalen);
-	datablob[datalen] = '\0';
-
 	options = trusted_options_alloc();
-	if (!options) {
-		ret = -ENOMEM;
-		goto out;
-	}
-	payload = trusted_payload_alloc(key);
-	if (!payload) {
-		ret = -ENOMEM;
-		goto out;
-	}
+	if (!options)
+		return -ENOMEM;
 
-	key_cmd = datablob_parse(datablob, payload, options);
-	if (key_cmd < 0) {
-		ret = key_cmd;
+	ret = getoptions(datablob, p, options);
+	if (ret < 0)
 		goto out;
-	}
+	dump_options(options);
 
 	if (!options->keyhandle && !tpm2) {
 		ret = -EINVAL;
 		goto out;
 	}
 
-	dump_payload(payload);
-	dump_options(options);
-
-	switch (key_cmd) {
-	case Opt_load:
-		if (tpm2)
-			ret = tpm2_unseal_trusted(chip, payload, options);
-		else
-			ret = key_unseal(payload, options);
-		dump_payload(payload);
-		dump_options(options);
-		if (ret < 0)
-			pr_info("trusted_key: key_unseal failed (%d)\n", ret);
-		break;
-	case Opt_new:
-		key_len = payload->key_len;
-		ret = tpm_get_random(chip, payload->key, key_len);
-		if (ret < 0)
-			goto out;
+	if (tpm2)
+		ret = tpm2_seal_trusted(chip, p, options);
+	else
+		ret = key_seal(p, options);
+	if (ret < 0) {
+		pr_info("key_seal failed (%d)\n", ret);
+		goto out;
+	}
 
-		if (ret != key_len) {
-			pr_info("trusted_key: key_create failed (%d)\n", ret);
-			ret = -EIO;
+	if (options->pcrlock) {
+		ret = pcrlock(options->pcrlock);
+		if (ret < 0) {
+			pr_info("pcrlock failed (%d)\n", ret);
 			goto out;
 		}
-		if (tpm2)
-			ret = tpm2_seal_trusted(chip, payload, options);
-		else
-			ret = key_seal(payload, options);
-		if (ret < 0)
-			pr_info("trusted_key: key_seal failed (%d)\n", ret);
-		break;
-	default:
-		ret = -EINVAL;
-		goto out;
 	}
-	if (!ret && options->pcrlock)
-		ret = pcrlock(options->pcrlock);
 out:
-	kfree_sensitive(datablob);
 	kfree_sensitive(options);
-	if (!ret)
-		rcu_assign_keypointer(key, payload);
-	else
-		kfree_sensitive(payload);
 	return ret;
 }
 
-static void trusted_rcu_free(struct rcu_head *rcu)
-{
-	struct trusted_key_payload *p;
-
-	p = container_of(rcu, struct trusted_key_payload, rcu);
-	kfree_sensitive(p);
-}
-
-/*
- * trusted_update - reseal an existing key with new PCR values
- */
-static int trusted_update(struct key *key, struct key_preparsed_payload *prep)
+static int trusted_tpm_unseal(struct trusted_key_payload *p, char *datablob)
 {
-	struct trusted_key_payload *p;
-	struct trusted_key_payload *new_p;
-	struct trusted_key_options *new_o;
-	size_t datalen = prep->datalen;
-	char *datablob;
+	struct trusted_key_options *options = NULL;
 	int ret = 0;
+	int tpm2;
 
-	if (key_is_negative(key))
-		return -ENOKEY;
-	p = key->payload.data[0];
-	if (!p->migratable)
-		return -EPERM;
-	if (datalen <= 0 || datalen > 32767 || !prep->data)
-		return -EINVAL;
+	tpm2 = tpm_is_tpm2(chip);
+	if (tpm2 < 0)
+		return tpm2;
 
-	datablob = kmalloc(datalen + 1, GFP_KERNEL);
-	if (!datablob)
+	options = trusted_options_alloc();
+	if (!options)
 		return -ENOMEM;
-	new_o = trusted_options_alloc();
-	if (!new_o) {
-		ret = -ENOMEM;
-		goto out;
-	}
-	new_p = trusted_payload_alloc(key);
-	if (!new_p) {
-		ret = -ENOMEM;
-		goto out;
-	}
 
-	memcpy(datablob, prep->data, datalen);
-	datablob[datalen] = '\0';
-	ret = datablob_parse(datablob, new_p, new_o);
-	if (ret != Opt_update) {
-		ret = -EINVAL;
-		kfree_sensitive(new_p);
+	ret = getoptions(datablob, p, options);
+	if (ret < 0)
 		goto out;
-	}
+	dump_options(options);
 
-	if (!new_o->keyhandle) {
+	if (!options->keyhandle) {
 		ret = -EINVAL;
-		kfree_sensitive(new_p);
 		goto out;
 	}
 
-	/* copy old key values, and reseal with new pcrs */
-	new_p->migratable = p->migratable;
-	new_p->key_len = p->key_len;
-	memcpy(new_p->key, p->key, p->key_len);
-	dump_payload(p);
-	dump_payload(new_p);
+	if (tpm2)
+		ret = tpm2_unseal_trusted(chip, p, options);
+	else
+		ret = key_unseal(p, options);
+	if (ret < 0)
+		pr_info("key_unseal failed (%d)\n", ret);
 
-	ret = key_seal(new_p, new_o);
-	if (ret < 0) {
-		pr_info("trusted_key: key_seal failed (%d)\n", ret);
-		kfree_sensitive(new_p);
-		goto out;
-	}
-	if (new_o->pcrlock) {
-		ret = pcrlock(new_o->pcrlock);
+	if (options->pcrlock) {
+		ret = pcrlock(options->pcrlock);
 		if (ret < 0) {
-			pr_info("trusted_key: pcrlock failed (%d)\n", ret);
-			kfree_sensitive(new_p);
+			pr_info("pcrlock failed (%d)\n", ret);
 			goto out;
 		}
 	}
-	rcu_assign_keypointer(key, new_p);
-	call_rcu(&p->rcu, trusted_rcu_free);
 out:
-	kfree_sensitive(datablob);
-	kfree_sensitive(new_o);
+	kfree_sensitive(options);
 	return ret;
 }
 
-/*
- * trusted_read - copy the sealed blob data to userspace in hex.
- * On success, return to userspace the trusted key datablob size.
- */
-static long trusted_read(const struct key *key, char *buffer,
-			 size_t buflen)
+static int trusted_tpm_get_random(unsigned char *key, size_t key_len)
 {
-	const struct trusted_key_payload *p;
-	char *bufp;
-	int i;
-
-	p = dereference_key_locked(key);
-	if (!p)
-		return -EINVAL;
-
-	if (buffer && buflen >= 2 * p->blob_len) {
-		bufp = buffer;
-		for (i = 0; i < p->blob_len; i++)
-			bufp = hex_byte_pack(bufp, p->blob[i]);
-	}
-	return 2 * p->blob_len;
+	return tpm_get_random(chip, key, key_len);
 }
 
-/*
- * trusted_destroy - clear and free the key's payload
- */
-static void trusted_destroy(struct key *key)
-{
-	kfree_sensitive(key->payload.data[0]);
-}
-
-struct key_type key_type_trusted = {
-	.name = "trusted",
-	.instantiate = trusted_instantiate,
-	.update = trusted_update,
-	.destroy = trusted_destroy,
-	.describe = user_describe,
-	.read = trusted_read,
-};
-
-EXPORT_SYMBOL_GPL(key_type_trusted);
-
 static void trusted_shash_release(void)
 {
 	if (hashalg)
@@ -1216,14 +987,14 @@ static int __init trusted_shash_alloc(void)
 
 	hmacalg = crypto_alloc_shash(hmac_alg, 0, 0);
 	if (IS_ERR(hmacalg)) {
-		pr_info("trusted_key: could not allocate crypto %s\n",
+		pr_info("could not allocate crypto %s\n",
 			hmac_alg);
 		return PTR_ERR(hmacalg);
 	}
 
 	hashalg = crypto_alloc_shash(hash_alg, 0, 0);
 	if (IS_ERR(hashalg)) {
-		pr_info("trusted_key: could not allocate crypto %s\n",
+		pr_info("could not allocate crypto %s\n",
 			hash_alg);
 		ret = PTR_ERR(hashalg);
 		goto hashalg_fail;
@@ -1251,16 +1022,13 @@ static int __init init_digests(void)
 	return 0;
 }
 
-static int __init init_trusted(void)
+static int __init trusted_tpm_init(void)
 {
 	int ret;
 
-	/* encrypted_keys.ko depends on successful load of this module even if
-	 * TPM is not used.
-	 */
 	chip = tpm_default_chip();
 	if (!chip)
-		return 0;
+		return -ENODEV;
 
 	ret = init_digests();
 	if (ret < 0)
@@ -1281,7 +1049,7 @@ err_put:
 	return ret;
 }
 
-static void __exit cleanup_trusted(void)
+static void trusted_tpm_exit(void)
 {
 	if (chip) {
 		put_device(&chip->dev);
@@ -1291,7 +1059,11 @@ static void __exit cleanup_trusted(void)
 	}
 }
 
-late_initcall(init_trusted);
-module_exit(cleanup_trusted);
-
-MODULE_LICENSE("GPL");
+struct trusted_key_ops trusted_key_tpm_ops = {
+	.migratable = 1, /* migratable by default */
+	.init = trusted_tpm_init,
+	.seal = trusted_tpm_seal,
+	.unseal = trusted_tpm_unseal,
+	.get_random = trusted_tpm_get_random,
+	.exit = trusted_tpm_exit,
+};