security/keys/trusted-keys/trusted_tee.c

   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  */
  51 struct 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
  58 static struct trusted_key_tee_private pvt_data;
  59
  60 /*
  61  * Have the TEE seal(encrypt) the symmetric key
  62  */
  63 static 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(pvt_data.ctx, (unsigned long)p->key,
  74                                       p->key_len, TEE_SHM_DMA_BUF |
  75                                       TEE_SHM_KERNEL_MAPPED);
  76         if (IS_ERR(reg_shm_in)) {
  77                 dev_err(pvt_data.dev, "key shm register failed\n");
  78                 return PTR_ERR(reg_shm_in);
  79         }
  80
  81         reg_shm_out = tee_shm_register(pvt_data.ctx, (unsigned long)p->blob,
  82                                        sizeof(p->blob), TEE_SHM_DMA_BUF |
  83                                        TEE_SHM_KERNEL_MAPPED);
  84         if (IS_ERR(reg_shm_out)) {
  85                 dev_err(pvt_data.dev, "blob shm register failed\n");
  86                 ret = PTR_ERR(reg_shm_out);
  87                 goto out;
  88         }
  89
  90         inv_arg.func = TA_CMD_SEAL;
  91         inv_arg.session = pvt_data.session_id;
  92         inv_arg.num_params = 4;
  93
  94         param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT;
  95         param[0].u.memref.shm = reg_shm_in;
  96         param[0].u.memref.size = p->key_len;
  97         param[0].u.memref.shm_offs = 0;
  98         param[1].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT;
  99         param[1].u.memref.shm = reg_shm_out;
 100         param[1].u.memref.size = sizeof(p->blob);
 101         param[1].u.memref.shm_offs = 0;
 102
 103         ret = tee_client_invoke_func(pvt_data.ctx, &inv_arg, param);
 104         if ((ret < 0) || (inv_arg.ret != 0)) {
 105                 dev_err(pvt_data.dev, "TA_CMD_SEAL invoke err: %x\n",
 106                         inv_arg.ret);
 107                 ret = -EFAULT;
 108         } else {
 109                 p->blob_len = param[1].u.memref.size;
 110         }
 111
 112 out:
 113         if (reg_shm_out)
 114                 tee_shm_free(reg_shm_out);
 115         if (reg_shm_in)
 116                 tee_shm_free(reg_shm_in);
 117
 118         return ret;
 119 }
 120
 121 /*
 122  * Have the TEE unseal(decrypt) the symmetric key
 123  */
 124 static int trusted_tee_unseal(struct trusted_key_payload *p, char *datablob)
 125 {
 126         int ret;
 127         struct tee_ioctl_invoke_arg inv_arg;
 128         struct tee_param param[4];
 129         struct tee_shm *reg_shm_in = NULL, *reg_shm_out = NULL;
 130
 131         memset(&inv_arg, 0, sizeof(inv_arg));
 132         memset(&param, 0, sizeof(param));
 133
 134         reg_shm_in = tee_shm_register(pvt_data.ctx, (unsigned long)p->blob,
 135                                       p->blob_len, TEE_SHM_DMA_BUF |
 136                                       TEE_SHM_KERNEL_MAPPED);
 137         if (IS_ERR(reg_shm_in)) {
 138                 dev_err(pvt_data.dev, "blob shm register failed\n");
 139                 return PTR_ERR(reg_shm_in);
 140         }
 141
 142         reg_shm_out = tee_shm_register(pvt_data.ctx, (unsigned long)p->key,
 143                                        sizeof(p->key), TEE_SHM_DMA_BUF |
 144                                        TEE_SHM_KERNEL_MAPPED);
 145         if (IS_ERR(reg_shm_out)) {
 146                 dev_err(pvt_data.dev, "key shm register failed\n");
 147                 ret = PTR_ERR(reg_shm_out);
 148                 goto out;
 149         }
 150
 151         inv_arg.func = TA_CMD_UNSEAL;
 152         inv_arg.session = pvt_data.session_id;
 153         inv_arg.num_params = 4;
 154
 155         param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT;
 156         param[0].u.memref.shm = reg_shm_in;
 157         param[0].u.memref.size = p->blob_len;
 158         param[0].u.memref.shm_offs = 0;
 159         param[1].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT;
 160         param[1].u.memref.shm = reg_shm_out;
 161         param[1].u.memref.size = sizeof(p->key);
 162         param[1].u.memref.shm_offs = 0;
 163
 164         ret = tee_client_invoke_func(pvt_data.ctx, &inv_arg, param);
 165         if ((ret < 0) || (inv_arg.ret != 0)) {
 166                 dev_err(pvt_data.dev, "TA_CMD_UNSEAL invoke err: %x\n",
 167                         inv_arg.ret);
 168                 ret = -EFAULT;
 169         } else {
 170                 p->key_len = param[1].u.memref.size;
 171         }
 172
 173 out:
 174         if (reg_shm_out)
 175                 tee_shm_free(reg_shm_out);
 176         if (reg_shm_in)
 177                 tee_shm_free(reg_shm_in);
 178
 179         return ret;
 180 }
 181
 182 /*
 183  * Have the TEE generate random symmetric key
 184  */
 185 static int trusted_tee_get_random(unsigned char *key, size_t key_len)
 186 {
 187         int ret;
 188         struct tee_ioctl_invoke_arg inv_arg;
 189         struct tee_param param[4];
 190         struct tee_shm *reg_shm = NULL;
 191
 192         memset(&inv_arg, 0, sizeof(inv_arg));
 193         memset(&param, 0, sizeof(param));
 194
 195         reg_shm = tee_shm_register(pvt_data.ctx, (unsigned long)key, key_len,
 196                                    TEE_SHM_DMA_BUF | TEE_SHM_KERNEL_MAPPED);
 197         if (IS_ERR(reg_shm)) {
 198                 dev_err(pvt_data.dev, "key shm register failed\n");
 199                 return PTR_ERR(reg_shm);
 200         }
 201
 202         inv_arg.func = TA_CMD_GET_RANDOM;
 203         inv_arg.session = pvt_data.session_id;
 204         inv_arg.num_params = 4;
 205
 206         param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT;
 207         param[0].u.memref.shm = reg_shm;
 208         param[0].u.memref.size = key_len;
 209         param[0].u.memref.shm_offs = 0;
 210
 211         ret = tee_client_invoke_func(pvt_data.ctx, &inv_arg, param);
 212         if ((ret < 0) || (inv_arg.ret != 0)) {
 213                 dev_err(pvt_data.dev, "TA_CMD_GET_RANDOM invoke err: %x\n",
 214                         inv_arg.ret);
 215                 ret = -EFAULT;
 216         } else {
 217                 ret = param[0].u.memref.size;
 218         }
 219
 220         tee_shm_free(reg_shm);
 221
 222         return ret;
 223 }
 224
 225 static int optee_ctx_match(struct tee_ioctl_version_data *ver, const void *data)
 226 {
 227         if (ver->impl_id == TEE_IMPL_ID_OPTEE)
 228                 return 1;
 229         else
 230                 return 0;
 231 }
 232
 233 static int trusted_key_probe(struct device *dev)
 234 {
 235         struct tee_client_device *rng_device = to_tee_client_device(dev);
 236         int ret;
 237         struct tee_ioctl_open_session_arg sess_arg;
 238
 239         memset(&sess_arg, 0, sizeof(sess_arg));
 240
 241         pvt_data.ctx = tee_client_open_context(NULL, optee_ctx_match, NULL,
 242                                                NULL);
 243         if (IS_ERR(pvt_data.ctx))
 244                 return -ENODEV;
 245
 246         memcpy(sess_arg.uuid, rng_device->id.uuid.b, TEE_IOCTL_UUID_LEN);
 247         sess_arg.clnt_login = TEE_IOCTL_LOGIN_REE_KERNEL;
 248         sess_arg.num_params = 0;
 249
 250         ret = tee_client_open_session(pvt_data.ctx, &sess_arg, NULL);
 251         if ((ret < 0) || (sess_arg.ret != 0)) {
 252                 dev_err(dev, "tee_client_open_session failed, err: %x\n",
 253                         sess_arg.ret);
 254                 ret = -EINVAL;
 255                 goto out_ctx;
 256         }
 257         pvt_data.session_id = sess_arg.session;
 258
 259         ret = register_key_type(&key_type_trusted);
 260         if (ret < 0)
 261                 goto out_sess;
 262
 263         pvt_data.dev = dev;
 264
 265         return 0;
 266
 267 out_sess:
 268         tee_client_close_session(pvt_data.ctx, pvt_data.session_id);
 269 out_ctx:
 270         tee_client_close_context(pvt_data.ctx);
 271
 272         return ret;
 273 }
 274
 275 static int trusted_key_remove(struct device *dev)
 276 {
 277         unregister_key_type(&key_type_trusted);
 278         tee_client_close_session(pvt_data.ctx, pvt_data.session_id);
 279         tee_client_close_context(pvt_data.ctx);
 280
 281         return 0;
 282 }
 283
 284 static const struct tee_client_device_id trusted_key_id_table[] = {
 285         {UUID_INIT(0xf04a0fe7, 0x1f5d, 0x4b9b,
 286                    0xab, 0xf7, 0x61, 0x9b, 0x85, 0xb4, 0xce, 0x8c)},
 287         {}
 288 };
 289 MODULE_DEVICE_TABLE(tee, trusted_key_id_table);
 290
 291 static struct tee_client_driver trusted_key_driver = {
 292         .id_table       = trusted_key_id_table,
 293         .driver         = {
 294                 .name           = DRIVER_NAME,
 295                 .bus            = &tee_bus_type,
 296                 .probe          = trusted_key_probe,
 297                 .remove         = trusted_key_remove,
 298         },
 299 };
 300
 301 static int trusted_tee_init(void)
 302 {
 303         return driver_register(&trusted_key_driver.driver);
 304 }
 305
 306 static void trusted_tee_exit(void)
 307 {
 308         driver_unregister(&trusted_key_driver.driver);
 309 }
 310
 311 struct trusted_key_ops trusted_key_tee_ops = {
 312         .migratable = 0, /* non-migratable */
 313         .init = trusted_tee_init,
 314         .seal = trusted_tee_seal,
 315         .unseal = trusted_tee_unseal,
 316         .get_random = trusted_tee_get_random,
 317         .exit = trusted_tee_exit,
 318 };