[PATCH v8 2/4] KEYS: trusted: Introduce TEE based Trusted Keys

Sumit Garg
2020-11-03T16:01:44Z

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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 aa4f2a0..15b1b0f3 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>
@@ -29,6 +30,9 @@ static const 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
};

DEFINE_STATIC_CALL_NULL(trusted_key_init, *trusted_key_sources[0].ops->init);
diff --git a/security/keys/trusted-keys/trusted_tee.c b/security/keys/trusted-keys/trusted_tee.c
new file mode 100644
index 0000000..da8785a
--- /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 trusted_tee_seal(struct trusted_key_payload *p, char *datablob)
+{
+ int ret;
+ 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 trusted_tee_unseal(struct trusted_key_payload *p, char *datablob)
+{
+ int ret;
+ 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 trusted_tee_get_random(unsigned char *key, size_t key_len)
+{
+ int ret;
+ 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;
+ struct tee_ioctl_open_session_arg sess_arg;
+
+ 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);
+ ret = -EINVAL;
+ 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 ret;
+}
+
+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 trusted_tee_init(void)
+{
+ return driver_register(&trusted_key_driver.driver);
+}
+
+static void trusted_tee_exit(void)
+{
+ driver_unregister(&trusted_key_driver.driver);
+}
+
+struct trusted_key_ops tee_trusted_key_ops = {
+ .migratable = 0, /* non-migratable */
+ .init = trusted_tee_init,
+ .seal = trusted_tee_seal,
+ .unseal = trusted_tee_unseal,
+ .get_random = trusted_tee_get_random,
+ .exit = trusted_tee_exit,
+};
--
2.7.4