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_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
 110 out:
 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  */
 122 static 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
 169 out:
 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  */
 181 static 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
 220 static int optee_ctx_match(struct tee_ioctl_version_data *ver, const void *data)
 221 {
 222         if (ver->impl_id == TEE_IMPL_ID_OPTEE)
 223                 return 1;
 224         else
 225                 return 0;
 226 }
 227
 228 static int trusted_key_probe(struct device *dev)
 229 {
 230         struct tee_client_device *rng_device = to_tee_client_device(dev);
 231         int ret;
 232         struct tee_ioctl_open_session_arg sess_arg;
 233
 234         memset(&sess_arg, 0, sizeof(sess_arg));
 235
 236         pvt_data.ctx = tee_client_open_context(NULL, optee_ctx_match, NULL,
 237                                                NULL);
 238         if (IS_ERR(pvt_data.ctx))
 239                 return -ENODEV;
 240
 241         memcpy(sess_arg.uuid, rng_device->id.uuid.b, TEE_IOCTL_UUID_LEN);
 242         sess_arg.clnt_login = TEE_IOCTL_LOGIN_REE_KERNEL;
 243         sess_arg.num_params = 0;
 244
 245         ret = tee_client_open_session(pvt_data.ctx, &sess_arg, NULL);
 246         if ((ret < 0) || (sess_arg.ret != 0)) {
 247                 dev_err(dev, "tee_client_open_session failed, err: %x\n",
 248                         sess_arg.ret);
 249                 ret = -EINVAL;
 250                 goto out_ctx;
 251         }
 252         pvt_data.session_id = sess_arg.session;
 253
 254         ret = register_key_type(&key_type_trusted);
 255         if (ret < 0)
 256                 goto out_sess;
 257
 258         pvt_data.dev = dev;
 259
 260         return 0;
 261
 262 out_sess:
 263         tee_client_close_session(pvt_data.ctx, pvt_data.session_id);
 264 out_ctx:
 265         tee_client_close_context(pvt_data.ctx);
 266
 267         return ret;
 268 }
 269
 270 static int trusted_key_remove(struct device *dev)
 271 {
 272         unregister_key_type(&key_type_trusted);
 273         tee_client_close_session(pvt_data.ctx, pvt_data.session_id);
 274         tee_client_close_context(pvt_data.ctx);
 275
 276         return 0;
 277 }
 278
 279 static const struct tee_client_device_id trusted_key_id_table[] = {
 280         {UUID_INIT(0xf04a0fe7, 0x1f5d, 0x4b9b,
 281                    0xab, 0xf7, 0x61, 0x9b, 0x85, 0xb4, 0xce, 0x8c)},
 282         {}
 283 };
 284 MODULE_DEVICE_TABLE(tee, trusted_key_id_table);
 285
 286 static struct tee_client_driver trusted_key_driver = {
 287         .id_table       = trusted_key_id_table,
 288         .driver         = {
 289                 .name           = DRIVER_NAME,
 290                 .bus            = &tee_bus_type,
 291                 .probe          = trusted_key_probe,
 292                 .remove         = trusted_key_remove,
 293         },
 294 };
 295
 296 static int trusted_tee_init(void)
 297 {
 298         return driver_register(&trusted_key_driver.driver);
 299 }
 300
 301 static void trusted_tee_exit(void)
 302 {
 303         driver_unregister(&trusted_key_driver.driver);
 304 }
 305
 306 struct trusted_key_ops trusted_key_tee_ops = {
 307         .migratable = 0, /* non-migratable */
 308         .init = trusted_tee_init,
 309         .seal = trusted_tee_seal,
 310         .unseal = trusted_tee_unseal,
 311         .get_random = trusted_tee_get_random,
 312         .exit = trusted_tee_exit,
 313 };