Re: [PATCH v7 2/4] KEYS: trusted: Introduce TEE based Trusted Keys

On Tue, 13 Oct 2020 at 07:22, Jarkko Sakkinen jarkko.sakkinen@linux.intel.com wrote:

On Wed, Oct 07, 2020 at 03:37:46PM +0530, Sumit Garg wrote:

...

Add support for TEE based trusted keys where TEE provides the functionality to seal and unseal trusted keys using hardware unique key.

Refer to Documentation/tee.txt for detailed information about TEE.

Signed-off-by: Sumit Garg sumit.garg@linaro.org

include/keys/trusted_tee.h | 55 ++++++ security/keys/trusted-keys/Makefile | 1 + security/keys/trusted-keys/trusted_core.c | 4 + security/keys/trusted-keys/trusted_tee.c | 278 ++++++++++++++++++++++++++++++ 4 files changed, 338 insertions(+) create mode 100644 include/keys/trusted_tee.h create mode 100644 security/keys/trusted-keys/trusted_tee.c

diff --git a/include/keys/trusted_tee.h b/include/keys/trusted_tee.h new file mode 100644 index 0000000..2e2bb15 --- /dev/null +++ b/include/keys/trusted_tee.h @@ -0,0 +1,55 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/*

• • Copyright (C) 2019-2020 Linaro Ltd.
• • Author:
• • Sumit Garg sumit.garg@linaro.org
• */

+#ifndef __TEE_TRUSTED_KEY_H +#define __TEE_TRUSTED_KEY_H

+#include <linux/tee_drv.h>

+#define DRIVER_NAME "tee-trusted-key"

+/*

• • Get random data for symmetric key
• • [out] memref[0] Random data
• */

+#define TA_CMD_GET_RANDOM 0x0

+/*

• • Seal trusted key using hardware unique key
• • [in] memref[0] Plain key
• • [out] memref[1] Sealed key datablob
• */

+#define TA_CMD_SEAL 0x1

+/*

• • Unseal trusted key using hardware unique key
• • [in] memref[0] Sealed key datablob
• • [out] memref[1] Plain key
• */

+#define TA_CMD_UNSEAL 0x2

+/**

• • struct trusted_key_private - TEE Trusted key private data
• • @dev: TEE based Trusted key device.
• • @ctx: TEE context handler.
• • @session_id: Trusted key TA session identifier.
• • @shm_pool: Memory pool shared with TEE device.
• */

+struct trusted_key_private {

• struct device *dev;
  

• struct tee_context *ctx;
  

• u32 session_id;
  

• struct tee_shm *shm_pool;
  

+};

+extern struct trusted_key_ops tee_trusted_key_ops;

+#endif diff --git a/security/keys/trusted-keys/Makefile b/security/keys/trusted-keys/Makefile index 49e3bcf..012dd78 100644 --- a/security/keys/trusted-keys/Makefile +++ b/security/keys/trusted-keys/Makefile @@ -7,3 +7,4 @@ obj-$(CONFIG_TRUSTED_KEYS) += trusted.o trusted-y += trusted_core.o trusted-y += trusted_tpm1.o trusted-y += trusted_tpm2.o +trusted-y += trusted_tee.o diff --git a/security/keys/trusted-keys/trusted_core.c b/security/keys/trusted-keys/trusted_core.c index 71a5e27..74a3d80 100644 --- a/security/keys/trusted-keys/trusted_core.c +++ b/security/keys/trusted-keys/trusted_core.c @@ -8,6 +8,7 @@

#include <keys/user-type.h> #include <keys/trusted-type.h> +#include <keys/trusted_tee.h> #include <keys/trusted_tpm.h> #include <linux/capability.h> #include <linux/err.h> @@ -28,6 +29,9 @@ static struct trusted_key_source trusted_key_sources[] = { #if defined(CONFIG_TCG_TPM) { "tpm", &tpm_trusted_key_ops }, #endif +#if defined(CONFIG_TEE)

• { "tee", &tee_trusted_key_ops },
  

+#endif }; static struct trusted_key_ops *trusted_key_ops;

diff --git a/security/keys/trusted-keys/trusted_tee.c b/security/keys/trusted-keys/trusted_tee.c new file mode 100644 index 0000000..b414d52 --- /dev/null +++ b/security/keys/trusted-keys/trusted_tee.c @@ -0,0 +1,278 @@ +// SPDX-License-Identifier: GPL-2.0 +/*

• • Copyright (C) 2019-2020 Linaro Ltd.
• • Author:
• • Sumit Garg sumit.garg@linaro.org
• */

+#include <linux/err.h> +#include <linux/key-type.h> +#include <linux/slab.h> +#include <linux/string.h> +#include <linux/uuid.h>

+#include <keys/trusted-type.h> +#include <keys/trusted_tee.h>

+static struct trusted_key_private pvt_data;

+/*

• • Have the TEE seal(encrypt) the symmetric key
• */

+static int tee_trusted_seal(struct trusted_key_payload *p, char *datablob)

Use trusted_tee_* prefix.

Okay, so will also switch to trusted_tpm_* prefix in patch #1 too.

...

+{

• int ret = 0;
  

"int ret;"

It is never used uninitialized.

Ack.

...

• struct tee_ioctl_invoke_arg inv_arg;
  

• struct tee_param param[4];
  

• struct tee_shm *reg_shm_in = NULL, *reg_shm_out = NULL;
  

• memset(&inv_arg, 0, sizeof(inv_arg));
  

• memset(&param, 0, sizeof(param));
  

• reg_shm_in = tee_shm_register(pvt_data.ctx, (unsigned long)p->key,
  

•                               p->key_len, TEE_SHM_DMA_BUF |
  

•                               TEE_SHM_KERNEL_MAPPED);
  

• if (IS_ERR(reg_shm_in)) {
  

•         dev_err(pvt_data.dev, "key shm register failed\n");
  

•         return PTR_ERR(reg_shm_in);
  

• }
  

• reg_shm_out = tee_shm_register(pvt_data.ctx, (unsigned long)p->blob,
  

•                                sizeof(p->blob), TEE_SHM_DMA_BUF |
  

•                                TEE_SHM_KERNEL_MAPPED);
  

• if (IS_ERR(reg_shm_out)) {
  

•         dev_err(pvt_data.dev, "blob shm register failed\n");
  

•         ret = PTR_ERR(reg_shm_out);
  

•         goto out;
  

• }
  

• inv_arg.func = TA_CMD_SEAL;
  

• inv_arg.session = pvt_data.session_id;
  

• inv_arg.num_params = 4;
  

• param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT;
  

• param[0].u.memref.shm = reg_shm_in;
  

• param[0].u.memref.size = p->key_len;
  

• param[0].u.memref.shm_offs = 0;
  

• param[1].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT;
  

• param[1].u.memref.shm = reg_shm_out;
  

• param[1].u.memref.size = sizeof(p->blob);
  

• param[1].u.memref.shm_offs = 0;
  

• ret = tee_client_invoke_func(pvt_data.ctx, &inv_arg, param);
  

• if ((ret < 0) || (inv_arg.ret != 0)) {
  

•         dev_err(pvt_data.dev, "TA_CMD_SEAL invoke err: %x\n",
  

•                 inv_arg.ret);
  

•         ret = -EFAULT;
  

• } else {
  

•         p->blob_len = param[1].u.memref.size;
  

• }
  

+out:

• if (reg_shm_out)
  

•         tee_shm_free(reg_shm_out);
  

• if (reg_shm_in)
  

•         tee_shm_free(reg_shm_in);
  

• return ret;
  

+}

+/*

• • Have the TEE unseal(decrypt) the symmetric key
• */

+static int tee_trusted_unseal(struct trusted_key_payload *p, char *datablob) +{

• int ret = 0;
  

Ditto.

Ack.

...

• struct tee_ioctl_invoke_arg inv_arg;
  

• struct tee_param param[4];
  

• struct tee_shm *reg_shm_in = NULL, *reg_shm_out = NULL;
  

• memset(&inv_arg, 0, sizeof(inv_arg));
  

• memset(&param, 0, sizeof(param));
  

• reg_shm_in = tee_shm_register(pvt_data.ctx, (unsigned long)p->blob,
  

•                               p->blob_len, TEE_SHM_DMA_BUF |
  

•                               TEE_SHM_KERNEL_MAPPED);
  

• if (IS_ERR(reg_shm_in)) {
  

•         dev_err(pvt_data.dev, "blob shm register failed\n");
  

•         return PTR_ERR(reg_shm_in);
  

• }
  

• reg_shm_out = tee_shm_register(pvt_data.ctx, (unsigned long)p->key,
  

•                                sizeof(p->key), TEE_SHM_DMA_BUF |
  

•                                TEE_SHM_KERNEL_MAPPED);
  

• if (IS_ERR(reg_shm_out)) {
  

•         dev_err(pvt_data.dev, "key shm register failed\n");
  

•         ret = PTR_ERR(reg_shm_out);
  

•         goto out;
  

• }
  

• inv_arg.func = TA_CMD_UNSEAL;
  

• inv_arg.session = pvt_data.session_id;
  

• inv_arg.num_params = 4;
  

• param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT;
  

• param[0].u.memref.shm = reg_shm_in;
  

• param[0].u.memref.size = p->blob_len;
  

• param[0].u.memref.shm_offs = 0;
  

• param[1].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT;
  

• param[1].u.memref.shm = reg_shm_out;
  

• param[1].u.memref.size = sizeof(p->key);
  

• param[1].u.memref.shm_offs = 0;
  

• ret = tee_client_invoke_func(pvt_data.ctx, &inv_arg, param);
  

• if ((ret < 0) || (inv_arg.ret != 0)) {
  

•         dev_err(pvt_data.dev, "TA_CMD_UNSEAL invoke err: %x\n",
  

•                 inv_arg.ret);
  

•         ret = -EFAULT;
  

• } else {
  

•         p->key_len = param[1].u.memref.size;
  

• }
  

+out:

• if (reg_shm_out)
  

•         tee_shm_free(reg_shm_out);
  

• if (reg_shm_in)
  

•         tee_shm_free(reg_shm_in);
  

• return ret;
  

+}

+/*

• • Have the TEE generate random symmetric key
• */

+static int tee_trusted_get_random(unsigned char *key, size_t key_len) +{

• int ret = 0;
  

Ditto.

Ack.

...

• struct tee_ioctl_invoke_arg inv_arg;
  

• struct tee_param param[4];
  

• struct tee_shm *reg_shm = NULL;
  

• memset(&inv_arg, 0, sizeof(inv_arg));
  

• memset(&param, 0, sizeof(param));
  

• reg_shm = tee_shm_register(pvt_data.ctx, (unsigned long)key, key_len,
  

•                            TEE_SHM_DMA_BUF | TEE_SHM_KERNEL_MAPPED);
  

• if (IS_ERR(reg_shm)) {
  

•         dev_err(pvt_data.dev, "key shm register failed\n");
  

•         return PTR_ERR(reg_shm);
  

• }
  

• inv_arg.func = TA_CMD_GET_RANDOM;
  

• inv_arg.session = pvt_data.session_id;
  

• inv_arg.num_params = 4;
  

• param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT;
  

• param[0].u.memref.shm = reg_shm;
  

• param[0].u.memref.size = key_len;
  

• param[0].u.memref.shm_offs = 0;
  

• ret = tee_client_invoke_func(pvt_data.ctx, &inv_arg, param);
  

• if ((ret < 0) || (inv_arg.ret != 0)) {
  

•         dev_err(pvt_data.dev, "TA_CMD_GET_RANDOM invoke err: %x\n",
  

•                 inv_arg.ret);
  

•         ret = -EFAULT;
  

• } else {
  

•         ret = param[0].u.memref.size;
  

• }
  

• tee_shm_free(reg_shm);
  

• return ret;
  

+}

+static int optee_ctx_match(struct tee_ioctl_version_data *ver, const void *data) +{

• if (ver->impl_id == TEE_IMPL_ID_OPTEE)
  

•         return 1;
  

• else
  

•         return 0;
  

+}

+static int trusted_key_probe(struct device *dev) +{

• struct tee_client_device *rng_device = to_tee_client_device(dev);
  

• int ret = 0, err = -ENODEV;
  

• struct tee_ioctl_open_session_arg sess_arg;
  

Ditto. I'm not sure why you need both 'ret' and 'err'.

Okay, will use 'ret' only.

...

• memset(&sess_arg, 0, sizeof(sess_arg));
  

• pvt_data.ctx = tee_client_open_context(NULL, optee_ctx_match, NULL,
  

•                                        NULL);
  

• if (IS_ERR(pvt_data.ctx))
  

•         return -ENODEV;
  

• memcpy(sess_arg.uuid, rng_device->id.uuid.b, TEE_IOCTL_UUID_LEN);
  

• sess_arg.clnt_login = TEE_IOCTL_LOGIN_REE_KERNEL;
  

• sess_arg.num_params = 0;
  

• ret = tee_client_open_session(pvt_data.ctx, &sess_arg, NULL);
  

• if ((ret < 0) || (sess_arg.ret != 0)) {
  

•         dev_err(dev, "tee_client_open_session failed, err: %x\n",
  

•                 sess_arg.ret);
  

•         err = -EINVAL;
  

Couldn't you just overwrite 'ret'?

Ack.

-Sumit

...

•         goto out_ctx;
  

• }
  

• pvt_data.session_id = sess_arg.session;
  

• ret = register_key_type(&key_type_trusted);
  

• if (ret < 0)
  

•         goto out_sess;
  

• pvt_data.dev = dev;
  

• return 0;
  

+out_sess:

• tee_client_close_session(pvt_data.ctx, pvt_data.session_id);
  

+out_ctx:

• tee_client_close_context(pvt_data.ctx);
  

• return err;
  

+}

+static int trusted_key_remove(struct device *dev) +{

• unregister_key_type(&key_type_trusted);
  

• tee_client_close_session(pvt_data.ctx, pvt_data.session_id);
  

• tee_client_close_context(pvt_data.ctx);
  

• return 0;
  

+}

+static const struct tee_client_device_id trusted_key_id_table[] = {

• {UUID_INIT(0xf04a0fe7, 0x1f5d, 0x4b9b,
  

•            0xab, 0xf7, 0x61, 0x9b, 0x85, 0xb4, 0xce, 0x8c)},
  

• {}
  

+}; +MODULE_DEVICE_TABLE(tee, trusted_key_id_table);

+static struct tee_client_driver trusted_key_driver = {

• .id_table       = trusted_key_id_table,
  

• .driver         = {
  

•         .name           = DRIVER_NAME,
  

•         .bus            = &tee_bus_type,
  

•         .probe          = trusted_key_probe,
  

•         .remove         = trusted_key_remove,
  

• },
  

+};

+static int __init init_tee_trusted(void) +{

• return driver_register(&trusted_key_driver.driver);
  

+}

+static void __exit exit_tee_trusted(void) +{

• driver_unregister(&trusted_key_driver.driver);
  

+}

+struct trusted_key_ops tee_trusted_key_ops = {

• .migratable = 0, /* non-migratable */
  

• .init = init_tee_trusted,
  

• .seal = tee_trusted_seal,
  

• .unseal = tee_trusted_unseal,
  

• .get_random = tee_trusted_get_random,
  

• .exit = exit_tee_trusted,
  

+};

2.7.4

/Jarkko