1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright (C) 2019-2021 Linaro Ltd.
  4 *
  5 * Author:
  6 * Sumit Garg <sumit.garg@linaro.org>
  7 */
  8
  9#include <linux/err.h>
 10#include <linux/key-type.h>
 11#include <linux/module.h>
 12#include <linux/slab.h>
 13#include <linux/string.h>
 14#include <linux/tee_drv.h>
 15#include <linux/uuid.h>
 16
 17#include <keys/trusted_tee.h>
 18
 19#define DRIVER_NAME "trusted-key-tee"
 20
 21/*
 22 * Get random data for symmetric key
 23 *
 24 * [out]     memref[0]        Random data
 25 */
 26#define TA_CMD_GET_RANDOM	0x0
 27
 28/*
 29 * Seal trusted key using hardware unique key
 30 *
 31 * [in]      memref[0]        Plain key
 32 * [out]     memref[1]        Sealed key datablob
 33 */
 34#define TA_CMD_SEAL		0x1
 35
 36/*
 37 * Unseal trusted key using hardware unique key
 38 *
 39 * [in]      memref[0]        Sealed key datablob
 40 * [out]     memref[1]        Plain key
 41 */
 42#define TA_CMD_UNSEAL		0x2
 43
 44/**
 45 * struct trusted_key_tee_private - TEE Trusted key private data
 46 * @dev:		TEE based Trusted key device.
 47 * @ctx:		TEE context handler.
 48 * @session_id:		Trusted key TA session identifier.
 49 * @shm_pool:		Memory pool shared with TEE device.
 50 */
 51struct trusted_key_tee_private {
 52	struct device *dev;
 53	struct tee_context *ctx;
 54	u32 session_id;
 55	struct tee_shm *shm_pool;
 56};
 57
 58static struct trusted_key_tee_private pvt_data;
 59
 60/*
 61 * Have the TEE seal(encrypt) the symmetric key
 62 */
 63static int trusted_tee_seal(struct trusted_key_payload *p, char *datablob)
 64{
 65	int ret;
 66	struct tee_ioctl_invoke_arg inv_arg;
 67	struct tee_param param[4];
 68	struct tee_shm *reg_shm = NULL;
 69
 70	memset(&inv_arg, 0, sizeof(inv_arg));
 71	memset(&param, 0, sizeof(param));
 72
 73	reg_shm = tee_shm_register_kernel_buf(pvt_data.ctx, p->key,
 74					      sizeof(p->key) + sizeof(p->blob));
 75	if (IS_ERR(reg_shm)) {
 76		dev_err(pvt_data.dev, "shm register failed\n");
 77		return PTR_ERR(reg_shm);
 78	}
 79
 80	inv_arg.func = TA_CMD_SEAL;
 81	inv_arg.session = pvt_data.session_id;
 82	inv_arg.num_params = 4;
 83
 84	param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT;
 85	param[0].u.memref.shm = reg_shm;
 86	param[0].u.memref.size = p->key_len;
 87	param[0].u.memref.shm_offs = 0;
 88	param[1].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT;
 89	param[1].u.memref.shm = reg_shm;
 90	param[1].u.memref.size = sizeof(p->blob);
 91	param[1].u.memref.shm_offs = sizeof(p->key);
 92
 93	ret = tee_client_invoke_func(pvt_data.ctx, &inv_arg, param);
 94	if ((ret < 0) || (inv_arg.ret != 0)) {
 95		dev_err(pvt_data.dev, "TA_CMD_SEAL invoke err: %x\n",
 96			inv_arg.ret);
 97		ret = -EFAULT;
 98	} else {
 99		p->blob_len = param[1].u.memref.size;
100	}
101
102	tee_shm_free(reg_shm);
103
104	return ret;
105}
106
107/*
108 * Have the TEE unseal(decrypt) the symmetric key
109 */
110static int trusted_tee_unseal(struct trusted_key_payload *p, char *datablob)
111{
112	int ret;
113	struct tee_ioctl_invoke_arg inv_arg;
114	struct tee_param param[4];
115	struct tee_shm *reg_shm = NULL;
116
117	memset(&inv_arg, 0, sizeof(inv_arg));
118	memset(&param, 0, sizeof(param));
119
120	reg_shm = tee_shm_register_kernel_buf(pvt_data.ctx, p->key,
121					      sizeof(p->key) + sizeof(p->blob));
122	if (IS_ERR(reg_shm)) {
123		dev_err(pvt_data.dev, "shm register failed\n");
124		return PTR_ERR(reg_shm);
125	}
126
127	inv_arg.func = TA_CMD_UNSEAL;
128	inv_arg.session = pvt_data.session_id;
129	inv_arg.num_params = 4;
130
131	param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT;
132	param[0].u.memref.shm = reg_shm;
133	param[0].u.memref.size = p->blob_len;
134	param[0].u.memref.shm_offs = sizeof(p->key);
135	param[1].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT;
136	param[1].u.memref.shm = reg_shm;
137	param[1].u.memref.size = sizeof(p->key);
138	param[1].u.memref.shm_offs = 0;
139
140	ret = tee_client_invoke_func(pvt_data.ctx, &inv_arg, param);
141	if ((ret < 0) || (inv_arg.ret != 0)) {
142		dev_err(pvt_data.dev, "TA_CMD_UNSEAL invoke err: %x\n",
143			inv_arg.ret);
144		ret = -EFAULT;
145	} else {
146		p->key_len = param[1].u.memref.size;
147	}
148
149	tee_shm_free(reg_shm);
150
151	return ret;
152}
153
154/*
155 * Have the TEE generate random symmetric key
156 */
157static int trusted_tee_get_random(unsigned char *key, size_t key_len)
158{
159	int ret;
160	struct tee_ioctl_invoke_arg inv_arg;
161	struct tee_param param[4];
162	struct tee_shm *reg_shm = NULL;
163
164	memset(&inv_arg, 0, sizeof(inv_arg));
165	memset(&param, 0, sizeof(param));
166
167	reg_shm = tee_shm_register_kernel_buf(pvt_data.ctx, key, key_len);
168	if (IS_ERR(reg_shm)) {
169		dev_err(pvt_data.dev, "key shm register failed\n");
170		return PTR_ERR(reg_shm);
171	}
172
173	inv_arg.func = TA_CMD_GET_RANDOM;
174	inv_arg.session = pvt_data.session_id;
175	inv_arg.num_params = 4;
176
177	param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT;
178	param[0].u.memref.shm = reg_shm;
179	param[0].u.memref.size = key_len;
180	param[0].u.memref.shm_offs = 0;
181
182	ret = tee_client_invoke_func(pvt_data.ctx, &inv_arg, param);
183	if ((ret < 0) || (inv_arg.ret != 0)) {
184		dev_err(pvt_data.dev, "TA_CMD_GET_RANDOM invoke err: %x\n",
185			inv_arg.ret);
186		ret = -EFAULT;
187	} else {
188		ret = param[0].u.memref.size;
189	}
190
191	tee_shm_free(reg_shm);
192
193	return ret;
194}
195
196static int optee_ctx_match(struct tee_ioctl_version_data *ver, const void *data)
197{
198	if (ver->impl_id == TEE_IMPL_ID_OPTEE &&
199	    ver->gen_caps & TEE_GEN_CAP_REG_MEM)
200		return 1;
201	else
202		return 0;
203}
204
205static int trusted_key_probe(struct device *dev)
206{
207	struct tee_client_device *rng_device = to_tee_client_device(dev);
208	int ret;
209	struct tee_ioctl_open_session_arg sess_arg;
210
211	memset(&sess_arg, 0, sizeof(sess_arg));
212
213	pvt_data.ctx = tee_client_open_context(NULL, optee_ctx_match, NULL,
214					       NULL);
215	if (IS_ERR(pvt_data.ctx))
216		return -ENODEV;
217
218	memcpy(sess_arg.uuid, rng_device->id.uuid.b, TEE_IOCTL_UUID_LEN);
219	sess_arg.clnt_login = TEE_IOCTL_LOGIN_REE_KERNEL;
220	sess_arg.num_params = 0;
221
222	ret = tee_client_open_session(pvt_data.ctx, &sess_arg, NULL);
223	if ((ret < 0) || (sess_arg.ret != 0)) {
224		dev_err(dev, "tee_client_open_session failed, err: %x\n",
225			sess_arg.ret);
226		ret = -EINVAL;
227		goto out_ctx;
228	}
229	pvt_data.session_id = sess_arg.session;
230
231	ret = register_key_type(&key_type_trusted);
232	if (ret < 0)
233		goto out_sess;
234
235	pvt_data.dev = dev;
236
237	return 0;
238
239out_sess:
240	tee_client_close_session(pvt_data.ctx, pvt_data.session_id);
241out_ctx:
242	tee_client_close_context(pvt_data.ctx);
243
244	return ret;
245}
246
247static int trusted_key_remove(struct device *dev)
248{
249	unregister_key_type(&key_type_trusted);
250	tee_client_close_session(pvt_data.ctx, pvt_data.session_id);
251	tee_client_close_context(pvt_data.ctx);
252
253	return 0;
254}
255
256static const struct tee_client_device_id trusted_key_id_table[] = {
257	{UUID_INIT(0xf04a0fe7, 0x1f5d, 0x4b9b,
258		   0xab, 0xf7, 0x61, 0x9b, 0x85, 0xb4, 0xce, 0x8c)},
259	{}
260};
261MODULE_DEVICE_TABLE(tee, trusted_key_id_table);
262
263static struct tee_client_driver trusted_key_driver = {
264	.id_table	= trusted_key_id_table,
265	.driver		= {
266		.name		= DRIVER_NAME,
267		.bus		= &tee_bus_type,
268		.probe		= trusted_key_probe,
269		.remove		= trusted_key_remove,
270	},
271};
272
273static int trusted_tee_init(void)
274{
275	return driver_register(&trusted_key_driver.driver);
276}
277
278static void trusted_tee_exit(void)
279{
280	driver_unregister(&trusted_key_driver.driver);
281}
282
283struct trusted_key_ops trusted_key_tee_ops = {
284	.migratable = 0, /* non-migratable */
285	.init = trusted_tee_init,
286	.seal = trusted_tee_seal,
287	.unseal = trusted_tee_unseal,
288	.get_random = trusted_tee_get_random,
289	.exit = trusted_tee_exit,
290};