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_in = NULL, *reg_shm_out = NULL;
 69
 70	memset(&inv_arg, 0, sizeof(inv_arg));
 71	memset(&param, 0, sizeof(param));
 72
 73	reg_shm_in = tee_shm_register_kernel_buf(pvt_data.ctx, p->key,
 74						 p->key_len);
 75	if (IS_ERR(reg_shm_in)) {
 76		dev_err(pvt_data.dev, "key shm register failed\n");
 77		return PTR_ERR(reg_shm_in);
 78	}
 79
 80	reg_shm_out = tee_shm_register_kernel_buf(pvt_data.ctx, p->blob,
 81						  sizeof(p->blob));
 82	if (IS_ERR(reg_shm_out)) {
 83		dev_err(pvt_data.dev, "blob shm register failed\n");
 84		ret = PTR_ERR(reg_shm_out);
 85		goto out;
 86	}
 87
 88	inv_arg.func = TA_CMD_SEAL;
 89	inv_arg.session = pvt_data.session_id;
 90	inv_arg.num_params = 4;
 91
 92	param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT;
 93	param[0].u.memref.shm = reg_shm_in;
 94	param[0].u.memref.size = p->key_len;
 95	param[0].u.memref.shm_offs = 0;
 96	param[1].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT;
 97	param[1].u.memref.shm = reg_shm_out;
 98	param[1].u.memref.size = sizeof(p->blob);
 99	param[1].u.memref.shm_offs = 0;
100
101	ret = tee_client_invoke_func(pvt_data.ctx, &inv_arg, param);
102	if ((ret < 0) || (inv_arg.ret != 0)) {
103		dev_err(pvt_data.dev, "TA_CMD_SEAL invoke err: %x\n",
104			inv_arg.ret);
105		ret = -EFAULT;
106	} else {
107		p->blob_len = param[1].u.memref.size;
108	}
109
110out:
111	if (reg_shm_out)
112		tee_shm_free(reg_shm_out);
113	if (reg_shm_in)
114		tee_shm_free(reg_shm_in);
115
116	return ret;
117}
118
119/*
120 * Have the TEE unseal(decrypt) the symmetric key
121 */
122static int trusted_tee_unseal(struct trusted_key_payload *p, char *datablob)
123{
124	int ret;
125	struct tee_ioctl_invoke_arg inv_arg;
126	struct tee_param param[4];
127	struct tee_shm *reg_shm_in = NULL, *reg_shm_out = NULL;
128
129	memset(&inv_arg, 0, sizeof(inv_arg));
130	memset(&param, 0, sizeof(param));
131
132	reg_shm_in = tee_shm_register_kernel_buf(pvt_data.ctx, p->blob,
133						 p->blob_len);
134	if (IS_ERR(reg_shm_in)) {
135		dev_err(pvt_data.dev, "blob shm register failed\n");
136		return PTR_ERR(reg_shm_in);
137	}
138
139	reg_shm_out = tee_shm_register_kernel_buf(pvt_data.ctx, p->key,
140						  sizeof(p->key));
141	if (IS_ERR(reg_shm_out)) {
142		dev_err(pvt_data.dev, "key shm register failed\n");
143		ret = PTR_ERR(reg_shm_out);
144		goto out;
145	}
146
147	inv_arg.func = TA_CMD_UNSEAL;
148	inv_arg.session = pvt_data.session_id;
149	inv_arg.num_params = 4;
150
151	param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT;
152	param[0].u.memref.shm = reg_shm_in;
153	param[0].u.memref.size = p->blob_len;
154	param[0].u.memref.shm_offs = 0;
155	param[1].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT;
156	param[1].u.memref.shm = reg_shm_out;
157	param[1].u.memref.size = sizeof(p->key);
158	param[1].u.memref.shm_offs = 0;
159
160	ret = tee_client_invoke_func(pvt_data.ctx, &inv_arg, param);
161	if ((ret < 0) || (inv_arg.ret != 0)) {
162		dev_err(pvt_data.dev, "TA_CMD_UNSEAL invoke err: %x\n",
163			inv_arg.ret);
164		ret = -EFAULT;
165	} else {
166		p->key_len = param[1].u.memref.size;
167	}
168
169out:
170	if (reg_shm_out)
171		tee_shm_free(reg_shm_out);
172	if (reg_shm_in)
173		tee_shm_free(reg_shm_in);
174
175	return ret;
176}
177
178/*
179 * Have the TEE generate random symmetric key
180 */
181static int trusted_tee_get_random(unsigned char *key, size_t key_len)
182{
183	int ret;
184	struct tee_ioctl_invoke_arg inv_arg;
185	struct tee_param param[4];
186	struct tee_shm *reg_shm = NULL;
187
188	memset(&inv_arg, 0, sizeof(inv_arg));
189	memset(&param, 0, sizeof(param));
190
191	reg_shm = tee_shm_register_kernel_buf(pvt_data.ctx, key, key_len);
192	if (IS_ERR(reg_shm)) {
193		dev_err(pvt_data.dev, "key shm register failed\n");
194		return PTR_ERR(reg_shm);
195	}
196
197	inv_arg.func = TA_CMD_GET_RANDOM;
198	inv_arg.session = pvt_data.session_id;
199	inv_arg.num_params = 4;
200
201	param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT;
202	param[0].u.memref.shm = reg_shm;
203	param[0].u.memref.size = key_len;
204	param[0].u.memref.shm_offs = 0;
205
206	ret = tee_client_invoke_func(pvt_data.ctx, &inv_arg, param);
207	if ((ret < 0) || (inv_arg.ret != 0)) {
208		dev_err(pvt_data.dev, "TA_CMD_GET_RANDOM invoke err: %x\n",
209			inv_arg.ret);
210		ret = -EFAULT;
211	} else {
212		ret = param[0].u.memref.size;
213	}
214
215	tee_shm_free(reg_shm);
216
217	return ret;
218}
219
220static int optee_ctx_match(struct tee_ioctl_version_data *ver, const void *data)
221{
222	if (ver->impl_id == TEE_IMPL_ID_OPTEE &&
223	    ver->gen_caps & TEE_GEN_CAP_REG_MEM)
224		return 1;
225	else
226		return 0;
227}
228
229static int trusted_key_probe(struct device *dev)
230{
231	struct tee_client_device *rng_device = to_tee_client_device(dev);
232	int ret;
233	struct tee_ioctl_open_session_arg sess_arg;
234
235	memset(&sess_arg, 0, sizeof(sess_arg));
236
237	pvt_data.ctx = tee_client_open_context(NULL, optee_ctx_match, NULL,
238					       NULL);
239	if (IS_ERR(pvt_data.ctx))
240		return -ENODEV;
241
242	memcpy(sess_arg.uuid, rng_device->id.uuid.b, TEE_IOCTL_UUID_LEN);
243	sess_arg.clnt_login = TEE_IOCTL_LOGIN_REE_KERNEL;
244	sess_arg.num_params = 0;
245
246	ret = tee_client_open_session(pvt_data.ctx, &sess_arg, NULL);
247	if ((ret < 0) || (sess_arg.ret != 0)) {
248		dev_err(dev, "tee_client_open_session failed, err: %x\n",
249			sess_arg.ret);
250		ret = -EINVAL;
251		goto out_ctx;
252	}
253	pvt_data.session_id = sess_arg.session;
254
255	ret = register_key_type(&key_type_trusted);
256	if (ret < 0)
257		goto out_sess;
258
259	pvt_data.dev = dev;
260
261	return 0;
262
263out_sess:
264	tee_client_close_session(pvt_data.ctx, pvt_data.session_id);
265out_ctx:
266	tee_client_close_context(pvt_data.ctx);
267
268	return ret;
269}
270
271static int trusted_key_remove(struct device *dev)
272{
273	unregister_key_type(&key_type_trusted);
274	tee_client_close_session(pvt_data.ctx, pvt_data.session_id);
275	tee_client_close_context(pvt_data.ctx);
276
277	return 0;
278}
279
280static const struct tee_client_device_id trusted_key_id_table[] = {
281	{UUID_INIT(0xf04a0fe7, 0x1f5d, 0x4b9b,
282		   0xab, 0xf7, 0x61, 0x9b, 0x85, 0xb4, 0xce, 0x8c)},
283	{}
284};
285MODULE_DEVICE_TABLE(tee, trusted_key_id_table);
286
287static struct tee_client_driver trusted_key_driver = {
288	.id_table	= trusted_key_id_table,
289	.driver		= {
290		.name		= DRIVER_NAME,
291		.bus		= &tee_bus_type,
292		.probe		= trusted_key_probe,
293		.remove		= trusted_key_remove,
294	},
295};
296
297static int trusted_tee_init(void)
298{
299	return driver_register(&trusted_key_driver.driver);
300}
301
302static void trusted_tee_exit(void)
303{
304	driver_unregister(&trusted_key_driver.driver);
305}
306
307struct trusted_key_ops trusted_key_tee_ops = {
308	.migratable = 0, /* non-migratable */
309	.init = trusted_tee_init,
310	.seal = trusted_tee_seal,
311	.unseal = trusted_tee_unseal,
312	.get_random = trusted_tee_get_random,
313	.exit = trusted_tee_exit,
314};