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 = 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  */
 110 static 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  */
 157 static 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
 196 static 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
 205 static 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
 239 out_sess:
 240         tee_client_close_session(pvt_data.ctx, pvt_data.session_id);
 241 out_ctx:
 242         tee_client_close_context(pvt_data.ctx);
 243
 244         return ret;
 245 }
 246
 247 static 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
 256 static 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 };
 261 MODULE_DEVICE_TABLE(tee, trusted_key_id_table);
 262
 263 static 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
 273 static int trusted_tee_init(void)
 274 {
 275         return driver_register(&trusted_key_driver.driver);
 276 }
 277
 278 static void trusted_tee_exit(void)
 279 {
 280         driver_unregister(&trusted_key_driver.driver);
 281 }
 282
 283 struct 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 };