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SubjectRe: [PATCH v4 1/4] KEYS: trusted: Add generic trusted keys framework
On Wed, May 06, 2020 at 03:10:14PM +0530, Sumit Garg wrote:
> 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 trusked keys
> support in case platform doesn't posses a TPM device.
>
> So this patch tries to add generic trusted keys framework where underlying
> implemtations like TPM, TEE etc. could be easily plugged-in.
>
> Suggested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
> ---
> include/keys/trusted-type.h | 45 ++++
> include/keys/trusted_tpm.h | 15 --
> security/keys/trusted-keys/Makefile | 1 +
> security/keys/trusted-keys/trusted_common.c | 333 +++++++++++++++++++++++++++
> security/keys/trusted-keys/trusted_tpm1.c | 335 +++++-----------------------
> 5 files changed, 437 insertions(+), 292 deletions(-)
> create mode 100644 security/keys/trusted-keys/trusted_common.c
>
> diff --git a/include/keys/trusted-type.h b/include/keys/trusted-type.h
> index a94c03a..5559010 100644
> --- a/include/keys/trusted-type.h
> +++ b/include/keys/trusted-type.h
> @@ -40,6 +40,51 @@ struct trusted_key_options {
> uint32_t policyhandle;
> };
>
> +struct trusted_key_ops {
> + /*
> + * flag to indicate if trusted key implementation supports migration
> + * or not.
> + */
> + unsigned char migratable;
> +
> + /* trusted key init */
> + int (*init)(void);
> +
> + /* seal a trusted key */
> + int (*seal)(struct trusted_key_payload *p, char *datablob);
> +
> + /* unseal a trusted key */
> + int (*unseal)(struct trusted_key_payload *p, char *datablob);
> +
> + /* get random trusted key */
> + int (*get_random)(unsigned char *key, size_t key_len);
> +
> + /* trusted key cleanup */
> + void (*cleanup)(void);
> +};
> +
> extern struct key_type key_type_trusted;
> +#if defined(CONFIG_TCG_TPM)
> +extern struct trusted_key_ops tpm_trusted_key_ops;
> +#endif
> +
> +#define TRUSTED_DEBUG 0
> +
> +#if TRUSTED_DEBUG
> +static inline void dump_payload(struct trusted_key_payload *p)
> +{
> + pr_info("trusted_key: key_len %d\n", p->key_len);
> + print_hex_dump(KERN_INFO, "key ", DUMP_PREFIX_NONE,
> + 16, 1, p->key, p->key_len, 0);
> + pr_info("trusted_key: bloblen %d\n", p->blob_len);
> + print_hex_dump(KERN_INFO, "blob ", DUMP_PREFIX_NONE,
> + 16, 1, p->blob, p->blob_len, 0);
> + pr_info("trusted_key: migratable %d\n", p->migratable);
> +}
> +#else
> +static inline void dump_payload(struct trusted_key_payload *p)
> +{
> +}
> +#endif
>
> #endif /* _KEYS_TRUSTED_TYPE_H */
> diff --git a/include/keys/trusted_tpm.h b/include/keys/trusted_tpm.h
> index a56d8e1..5753231 100644
> --- a/include/keys/trusted_tpm.h
> +++ b/include/keys/trusted_tpm.h
> @@ -60,17 +60,6 @@ static inline void dump_options(struct trusted_key_options *o)
> 16, 1, o->pcrinfo, o->pcrinfo_len, 0);
> }
>
> -static inline void dump_payload(struct trusted_key_payload *p)
> -{
> - pr_info("trusted_key: key_len %d\n", p->key_len);
> - print_hex_dump(KERN_INFO, "key ", DUMP_PREFIX_NONE,
> - 16, 1, p->key, p->key_len, 0);
> - pr_info("trusted_key: bloblen %d\n", p->blob_len);
> - print_hex_dump(KERN_INFO, "blob ", DUMP_PREFIX_NONE,
> - 16, 1, p->blob, p->blob_len, 0);
> - pr_info("trusted_key: migratable %d\n", p->migratable);
> -}
> -
> static inline void dump_sess(struct osapsess *s)
> {
> print_hex_dump(KERN_INFO, "trusted-key: handle ", DUMP_PREFIX_NONE,
> @@ -96,10 +85,6 @@ static inline void dump_options(struct trusted_key_options *o)
> {
> }
>
> -static inline void dump_payload(struct trusted_key_payload *p)
> -{
> -}
> -
> static inline void dump_sess(struct osapsess *s)
> {
> }
> diff --git a/security/keys/trusted-keys/Makefile b/security/keys/trusted-keys/Makefile
> index 7b73ceb..2b1085b 100644
> --- a/security/keys/trusted-keys/Makefile
> +++ b/security/keys/trusted-keys/Makefile
> @@ -4,5 +4,6 @@
> #
>
> obj-$(CONFIG_TRUSTED_KEYS) += trusted.o
> +trusted-y += trusted_common.o
> trusted-y += trusted_tpm1.o
> trusted-y += trusted_tpm2.o
> diff --git a/security/keys/trusted-keys/trusted_common.c b/security/keys/trusted-keys/trusted_common.c
> new file mode 100644
> index 0000000..9bfd081
> --- /dev/null
> +++ b/security/keys/trusted-keys/trusted_common.c
> @@ -0,0 +1,333 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2010 IBM Corporation
> + * Copyright (c) 2019, Linaro Limited
> + *
> + * Author:
> + * David Safford <safford@us.ibm.com>
> + * Added generic trusted key framework: Sumit Garg <sumit.garg@linaro.org>
> + *
> + * See Documentation/security/keys/trusted-encrypted.rst
> + */
> +
> +#include <keys/user-type.h>
> +#include <keys/trusted-type.h>
> +#include <linux/capability.h>
> +#include <linux/err.h>
> +#include <linux/init.h>
> +#include <linux/key-type.h>
> +#include <linux/module.h>
> +#include <linux/parser.h>
> +#include <linux/rcupdate.h>
> +#include <linux/slab.h>
> +#include <linux/string.h>
> +#include <linux/uaccess.h>
> +
> +static struct trusted_key_ops *available_tk_ops[] = {
> +#if defined(CONFIG_TCG_TPM)
> + &tpm_trusted_key_ops,
> +#endif
> +};

This, I think is wrong. You should have a compile time flag for TPM e.g.
CONFIG_TRUSTED_TPM, not this dynamic mess.

Please make the whole choice compile time, not run-time.

> +static struct trusted_key_ops *tk_ops;
> +
> +enum {
> + Opt_err,
> + Opt_new, Opt_load, Opt_update,
> +};
> +
> +static const match_table_t key_tokens = {
> + {Opt_new, "new"},
> + {Opt_load, "load"},
> + {Opt_update, "update"},
> + {Opt_err, NULL}
> +};
> +
> +/*
> + * datablob_parse - parse the keyctl data and fill in the
> + * payload structure
> + *
> + * On success returns 0, otherwise -EINVAL.
> + */
> +static int datablob_parse(char *datablob, struct trusted_key_payload *p)
> +{
> + 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 = 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 = Opt_load;
> + break;
> + case Opt_update:
> + ret = Opt_update;
> + break;
> + case Opt_err:
> + return -EINVAL;
> + }
> + return ret;
> +}
> +
> +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);
> +
> + p->migratable = tk_ops->migratable;
> +
> + 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)
> +{
> + struct trusted_key_payload *payload = NULL;
> + size_t datalen = prep->datalen;
> + char *datablob;
> + int ret = 0;
> + int key_cmd;
> + size_t key_len;
> +
> + 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';
> +
> + payload = trusted_payload_alloc(key);
> + if (!payload) {
> + ret = -ENOMEM;
> + goto out;
> + }
> +
> + key_cmd = datablob_parse(datablob, payload);
> + if (key_cmd < 0) {
> + ret = key_cmd;
> + goto out;
> + }
> +
> + dump_payload(payload);
> +
> + switch (key_cmd) {
> + case Opt_load:
> + ret = tk_ops->unseal(payload, datablob);
> + dump_payload(payload);
> + if (ret < 0)
> + pr_info("trusted_key: key_unseal failed (%d)\n", ret);
> + break;
> + case Opt_new:
> + key_len = payload->key_len;
> + ret = tk_ops->get_random(payload->key, key_len);
> + if (ret != key_len) {
> + pr_info("trusted_key: key_create failed (%d)\n", ret);
> + goto out;
> + }
> +
> + ret = tk_ops->seal(payload, datablob);
> + if (ret < 0)
> + pr_info("trusted_key: key_seal failed (%d)\n", ret);
> + break;
> + default:
> + ret = -EINVAL;
> + }
> +out:
> + kzfree(datablob);
> + if (!ret)
> + rcu_assign_keypointer(key, payload);
> + else
> + kzfree(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);
> + kzfree(p);
> +}
> +
> +/*
> + * trusted_update - reseal an existing key with new PCR values
> + */
> +static int trusted_update(struct key *key, struct key_preparsed_payload *prep)
> +{
> + struct trusted_key_payload *p;
> + struct trusted_key_payload *new_p;
> + size_t datalen = prep->datalen;
> + char *datablob;
> + int ret = 0;
> +
> + 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;
> +
> + datablob = kmalloc(datalen + 1, GFP_KERNEL);
> + if (!datablob)
> + return -ENOMEM;
> +
> + 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);
> + if (ret != Opt_update) {
> + ret = -EINVAL;
> + kzfree(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);
> +
> + ret = tk_ops->seal(new_p, datablob);
> + if (ret < 0) {
> + pr_info("trusted_key: key_seal failed (%d)\n", ret);
> + kzfree(new_p);
> + goto out;
> + }
> +
> + rcu_assign_keypointer(key, new_p);
> + call_rcu(&p->rcu, trusted_rcu_free);
> +out:
> + kzfree(datablob);
> + 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)
> +{
> + 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;
> +}
> +
> +/*
> + * trusted_destroy - clear and free the key's payload
> + */
> +static void trusted_destroy(struct key *key)
> +{
> + kzfree(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 int __init init_trusted(void)
> +{
> + int i, ret = 0;
> +
> + for (i = 0; i < sizeof(available_tk_ops); i++) {
> + tk_ops = available_tk_ops[i];
> +
> + if (!(tk_ops && tk_ops->init && tk_ops->seal &&
> + tk_ops->unseal && tk_ops->get_random))
> + continue;

This check should not exist as there is no legit case for any of these
callbacks missing. Please remove it.

> +
> + ret = tk_ops->init();
> + if (ret) {
> + if (tk_ops->cleanup)
> + tk_ops->cleanup();

Why is clean up called? What is "clean up"? Init should take care clean
up its dirt if it fails. Please remove the calll to clean up from here.

/Jarkko

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