1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2018-2019 Linaro Ltd. 4 */ 5 6 #include <linux/delay.h> 7 #include <linux/of.h> 8 #include <linux/hw_random.h> 9 #include <linux/kernel.h> 10 #include <linux/module.h> 11 #include <linux/slab.h> 12 #include <linux/tee_drv.h> 13 #include <linux/uuid.h> 14 15 #define DRIVER_NAME "optee-rng" 16 17 #define TEE_ERROR_HEALTH_TEST_FAIL 0x00000001 18 19 /* 20 * TA_CMD_GET_ENTROPY - Get Entropy from RNG 21 * 22 * param[0] (inout memref) - Entropy buffer memory reference 23 * param[1] unused 24 * param[2] unused 25 * param[3] unused 26 * 27 * Result: 28 * TEE_SUCCESS - Invoke command success 29 * TEE_ERROR_BAD_PARAMETERS - Incorrect input param 30 * TEE_ERROR_NOT_SUPPORTED - Requested entropy size greater than size of pool 31 * TEE_ERROR_HEALTH_TEST_FAIL - Continuous health testing failed 32 */ 33 #define TA_CMD_GET_ENTROPY 0x0 34 35 /* 36 * TA_CMD_GET_RNG_INFO - Get RNG information 37 * 38 * param[0] (out value) - value.a: RNG data-rate in bytes per second 39 * value.b: Quality/Entropy per 1024 bit of data 40 * param[1] unused 41 * param[2] unused 42 * param[3] unused 43 * 44 * Result: 45 * TEE_SUCCESS - Invoke command success 46 * TEE_ERROR_BAD_PARAMETERS - Incorrect input param 47 */ 48 #define TA_CMD_GET_RNG_INFO 0x1 49 50 #define MAX_ENTROPY_REQ_SZ (4 * 1024) 51 52 /** 53 * struct optee_rng_private - OP-TEE Random Number Generator private data 54 * @dev: OP-TEE based RNG device. 55 * @ctx: OP-TEE context handler. 56 * @session_id: RNG TA session identifier. 57 * @data_rate: RNG data rate. 58 * @entropy_shm_pool: Memory pool shared with RNG device. 59 * @optee_rng: OP-TEE RNG driver structure. 60 */ 61 struct optee_rng_private { 62 struct device *dev; 63 struct tee_context *ctx; 64 u32 session_id; 65 u32 data_rate; 66 struct tee_shm *entropy_shm_pool; 67 struct hwrng optee_rng; 68 }; 69 70 #define to_optee_rng_private(r) \ 71 container_of(r, struct optee_rng_private, optee_rng) 72 73 static size_t get_optee_rng_data(struct optee_rng_private *pvt_data, 74 void *buf, size_t req_size) 75 { 76 int ret = 0; 77 u8 *rng_data = NULL; 78 size_t rng_size = 0; 79 struct tee_ioctl_invoke_arg inv_arg; 80 struct tee_param param[4]; 81 82 memset(&inv_arg, 0, sizeof(inv_arg)); 83 memset(¶m, 0, sizeof(param)); 84 85 /* Invoke TA_CMD_GET_ENTROPY function of Trusted App */ 86 inv_arg.func = TA_CMD_GET_ENTROPY; 87 inv_arg.session = pvt_data->session_id; 88 inv_arg.num_params = 4; 89 90 /* Fill invoke cmd params */ 91 param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INOUT; 92 param[0].u.memref.shm = pvt_data->entropy_shm_pool; 93 param[0].u.memref.size = req_size; 94 param[0].u.memref.shm_offs = 0; 95 96 ret = tee_client_invoke_func(pvt_data->ctx, &inv_arg, param); 97 if ((ret < 0) || (inv_arg.ret != 0)) { 98 dev_err(pvt_data->dev, "TA_CMD_GET_ENTROPY invoke err: %x\n", 99 inv_arg.ret); 100 return 0; 101 } 102 103 rng_data = tee_shm_get_va(pvt_data->entropy_shm_pool, 0); 104 if (IS_ERR(rng_data)) { 105 dev_err(pvt_data->dev, "tee_shm_get_va failed\n"); 106 return 0; 107 } 108 109 rng_size = param[0].u.memref.size; 110 memcpy(buf, rng_data, rng_size); 111 112 return rng_size; 113 } 114 115 static int optee_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait) 116 { 117 struct optee_rng_private *pvt_data = to_optee_rng_private(rng); 118 size_t read = 0, rng_size = 0; 119 int timeout = 1; 120 u8 *data = buf; 121 122 if (max > MAX_ENTROPY_REQ_SZ) 123 max = MAX_ENTROPY_REQ_SZ; 124 125 while (read < max) { 126 rng_size = get_optee_rng_data(pvt_data, data, (max - read)); 127 128 data += rng_size; 129 read += rng_size; 130 131 if (wait && pvt_data->data_rate) { 132 if ((timeout-- == 0) || (read == max)) 133 return read; 134 msleep((1000 * (max - read)) / pvt_data->data_rate); 135 } else { 136 return read; 137 } 138 } 139 140 return read; 141 } 142 143 static int optee_rng_init(struct hwrng *rng) 144 { 145 struct optee_rng_private *pvt_data = to_optee_rng_private(rng); 146 struct tee_shm *entropy_shm_pool = NULL; 147 148 entropy_shm_pool = tee_shm_alloc_kernel_buf(pvt_data->ctx, 149 MAX_ENTROPY_REQ_SZ); 150 if (IS_ERR(entropy_shm_pool)) { 151 dev_err(pvt_data->dev, "tee_shm_alloc_kernel_buf failed\n"); 152 return PTR_ERR(entropy_shm_pool); 153 } 154 155 pvt_data->entropy_shm_pool = entropy_shm_pool; 156 157 return 0; 158 } 159 160 static void optee_rng_cleanup(struct hwrng *rng) 161 { 162 struct optee_rng_private *pvt_data = to_optee_rng_private(rng); 163 164 tee_shm_free(pvt_data->entropy_shm_pool); 165 } 166 167 static struct optee_rng_private pvt_data = { 168 .optee_rng = { 169 .name = DRIVER_NAME, 170 .init = optee_rng_init, 171 .cleanup = optee_rng_cleanup, 172 .read = optee_rng_read, 173 } 174 }; 175 176 static int get_optee_rng_info(struct device *dev) 177 { 178 int ret = 0; 179 struct tee_ioctl_invoke_arg inv_arg; 180 struct tee_param param[4]; 181 182 memset(&inv_arg, 0, sizeof(inv_arg)); 183 memset(¶m, 0, sizeof(param)); 184 185 /* Invoke TA_CMD_GET_RNG_INFO function of Trusted App */ 186 inv_arg.func = TA_CMD_GET_RNG_INFO; 187 inv_arg.session = pvt_data.session_id; 188 inv_arg.num_params = 4; 189 190 /* Fill invoke cmd params */ 191 param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_OUTPUT; 192 193 ret = tee_client_invoke_func(pvt_data.ctx, &inv_arg, param); 194 if ((ret < 0) || (inv_arg.ret != 0)) { 195 dev_err(dev, "TA_CMD_GET_RNG_INFO invoke err: %x\n", 196 inv_arg.ret); 197 return -EINVAL; 198 } 199 200 pvt_data.data_rate = param[0].u.value.a; 201 pvt_data.optee_rng.quality = param[0].u.value.b; 202 203 return 0; 204 } 205 206 static int optee_ctx_match(struct tee_ioctl_version_data *ver, const void *data) 207 { 208 if (ver->impl_id == TEE_IMPL_ID_OPTEE) 209 return 1; 210 else 211 return 0; 212 } 213 214 static int optee_rng_probe(struct device *dev) 215 { 216 struct tee_client_device *rng_device = to_tee_client_device(dev); 217 int ret = 0, err = -ENODEV; 218 struct tee_ioctl_open_session_arg sess_arg; 219 220 memset(&sess_arg, 0, sizeof(sess_arg)); 221 222 /* Open context with TEE driver */ 223 pvt_data.ctx = tee_client_open_context(NULL, optee_ctx_match, NULL, 224 NULL); 225 if (IS_ERR(pvt_data.ctx)) 226 return -ENODEV; 227 228 /* Open session with hwrng Trusted App */ 229 export_uuid(sess_arg.uuid, &rng_device->id.uuid); 230 sess_arg.clnt_login = TEE_IOCTL_LOGIN_PUBLIC; 231 sess_arg.num_params = 0; 232 233 ret = tee_client_open_session(pvt_data.ctx, &sess_arg, NULL); 234 if ((ret < 0) || (sess_arg.ret != 0)) { 235 dev_err(dev, "tee_client_open_session failed, err: %x\n", 236 sess_arg.ret); 237 err = -EINVAL; 238 goto out_ctx; 239 } 240 pvt_data.session_id = sess_arg.session; 241 242 err = get_optee_rng_info(dev); 243 if (err) 244 goto out_sess; 245 246 err = devm_hwrng_register(dev, &pvt_data.optee_rng); 247 if (err) { 248 dev_err(dev, "hwrng registration failed (%d)\n", err); 249 goto out_sess; 250 } 251 252 pvt_data.dev = dev; 253 254 return 0; 255 256 out_sess: 257 tee_client_close_session(pvt_data.ctx, pvt_data.session_id); 258 out_ctx: 259 tee_client_close_context(pvt_data.ctx); 260 261 return err; 262 } 263 264 static int optee_rng_remove(struct device *dev) 265 { 266 tee_client_close_session(pvt_data.ctx, pvt_data.session_id); 267 tee_client_close_context(pvt_data.ctx); 268 269 return 0; 270 } 271 272 static const struct tee_client_device_id optee_rng_id_table[] = { 273 {UUID_INIT(0xab7a617c, 0xb8e7, 0x4d8f, 274 0x83, 0x01, 0xd0, 0x9b, 0x61, 0x03, 0x6b, 0x64)}, 275 {} 276 }; 277 278 MODULE_DEVICE_TABLE(tee, optee_rng_id_table); 279 280 static struct tee_client_driver optee_rng_driver = { 281 .id_table = optee_rng_id_table, 282 .driver = { 283 .name = DRIVER_NAME, 284 .bus = &tee_bus_type, 285 .probe = optee_rng_probe, 286 .remove = optee_rng_remove, 287 }, 288 }; 289 290 static int __init optee_rng_mod_init(void) 291 { 292 return driver_register(&optee_rng_driver.driver); 293 } 294 295 static void __exit optee_rng_mod_exit(void) 296 { 297 driver_unregister(&optee_rng_driver.driver); 298 } 299 300 module_init(optee_rng_mod_init); 301 module_exit(optee_rng_mod_exit); 302 303 MODULE_LICENSE("GPL v2"); 304 MODULE_AUTHOR("Sumit Garg <sumit.garg@linaro.org>"); 305 MODULE_DESCRIPTION("OP-TEE based random number generator driver"); 306