drivers/tpm/tpm_tis_sandbox.c

   1 /*
   2  * Copyright (c) 2013 Google, Inc
   3  *
   4  * SPDX-License-Identifier:     GPL-2.0+
   5  */
   6
   7 #include <common.h>
   8 #include <dm.h>
   9 #include <tpm.h>
  10 #include <asm/state.h>
  11 #include <asm/unaligned.h>
  12 #include <linux/crc8.h>
  13
  14 /* TPM NVRAM location indices. */
  15 #define FIRMWARE_NV_INDEX               0x1007
  16 #define KERNEL_NV_INDEX                 0x1008
  17
  18 #define NV_DATA_PUBLIC_PERMISSIONS_OFFSET       60
  19
  20 /* Kernel TPM space - KERNEL_NV_INDEX, locked with physical presence */
  21 #define ROLLBACK_SPACE_KERNEL_VERSION   2
  22 #define ROLLBACK_SPACE_KERNEL_UID       0x4752574C  /* 'GRWL' */
  23
  24 struct rollback_space_kernel {
  25         /* Struct version, for backwards compatibility */
  26         uint8_t struct_version;
  27         /* Unique ID to detect space redefinition */
  28         uint32_t uid;
  29         /* Kernel versions */
  30         uint32_t kernel_versions;
  31         /* Reserved for future expansion */
  32         uint8_t reserved[3];
  33         /* Checksum (v2 and later only) */
  34         uint8_t crc8;
  35 } __packed rollback_space_kernel;
  36
  37 /*
  38  * These numbers derive from adding the sizes of command fields as shown in
  39  * the TPM commands manual.
  40  */
  41 #define TPM_REQUEST_HEADER_LENGTH       10
  42 #define TPM_RESPONSE_HEADER_LENGTH      10
  43
  44 /* These are the different non-volatile spaces that we emulate */
  45 enum {
  46         NV_GLOBAL_LOCK,
  47         NV_SEQ_FIRMWARE,
  48         NV_SEQ_KERNEL,
  49         NV_SEQ_COUNT,
  50 };
  51
  52 /* Size of each non-volatile space */
  53 #define NV_DATA_SIZE            0x20
  54
  55 /*
  56  * Information about our TPM emulation. This is preserved in the sandbox
  57  * state file if enabled.
  58  */
  59 static struct tpm_state {
  60         uint8_t nvdata[NV_SEQ_COUNT][NV_DATA_SIZE];
  61 } g_state;
  62
  63 /**
  64  * sandbox_tpm_read_state() - read the sandbox EC state from the state file
  65  *
  66  * If data is available, then blob and node will provide access to it. If
  67  * not this function sets up an empty TPM.
  68  *
  69  * @blob: Pointer to device tree blob, or NULL if no data to read
  70  * @node: Node offset to read from
  71  */
  72 static int sandbox_tpm_read_state(const void *blob, int node)
  73 {
  74         const char *prop;
  75         int len;
  76         int i;
  77
  78         if (!blob)
  79                 return 0;
  80
  81         for (i = 0; i < NV_SEQ_COUNT; i++) {
  82                 char prop_name[20];
  83
  84                 sprintf(prop_name, "nvdata%d", i);
  85                 prop = fdt_getprop(blob, node, prop_name, &len);
  86                 if (prop && len == NV_DATA_SIZE)
  87                         memcpy(g_state.nvdata[i], prop, NV_DATA_SIZE);
  88         }
  89
  90         return 0;
  91 }
  92
  93 /**
  94  * cros_ec_write_state() - Write out our state to the state file
  95  *
  96  * The caller will ensure that there is a node ready for the state. The node
  97  * may already contain the old state, in which case it is overridden.
  98  *
  99  * @blob: Device tree blob holding state
 100  * @node: Node to write our state into
 101  */
 102 static int sandbox_tpm_write_state(void *blob, int node)
 103 {
 104         int i;
 105
 106         /*
 107          * We are guaranteed enough space to write basic properties.
 108          * We could use fdt_add_subnode() to put each set of data in its
 109          * own node - perhaps useful if we add access informaiton to each.
 110          */
 111         for (i = 0; i < NV_SEQ_COUNT; i++) {
 112                 char prop_name[20];
 113
 114                 sprintf(prop_name, "nvdata%d", i);
 115                 fdt_setprop(blob, node, prop_name, g_state.nvdata[i],
 116                             NV_DATA_SIZE);
 117         }
 118
 119         return 0;
 120 }
 121
 122 SANDBOX_STATE_IO(sandbox_tpm, "google,sandbox-tpm", sandbox_tpm_read_state,
 123                  sandbox_tpm_write_state);
 124
 125 static int index_to_seq(uint32_t index)
 126 {
 127         switch (index) {
 128         case FIRMWARE_NV_INDEX:
 129                 return NV_SEQ_FIRMWARE;
 130         case KERNEL_NV_INDEX:
 131                 return NV_SEQ_KERNEL;
 132         case 0:
 133                 return NV_GLOBAL_LOCK;
 134         }
 135
 136         printf("Invalid nv index %#x\n", index);
 137         return -1;
 138 }
 139
 140 static int sandbox_tpm_xfer(struct udevice *dev, const uint8_t *sendbuf,
 141                             size_t send_size, uint8_t *recvbuf,
 142                             size_t *recv_len)
 143 {
 144         struct tpm_state *tpm = dev_get_priv(dev);
 145         uint32_t code, index, length, type;
 146         uint8_t *data;
 147         int seq;
 148
 149         code = get_unaligned_be32(sendbuf + sizeof(uint16_t) +
 150                                   sizeof(uint32_t));
 151         printf("tpm: %zd bytes, recv_len %zd, cmd = %x\n", send_size,
 152                *recv_len, code);
 153         print_buffer(0, sendbuf, 1, send_size, 0);
 154         switch (code) {
 155         case 0x65: /* get flags */
 156                 type = get_unaligned_be32(sendbuf + 14);
 157                 switch (type) {
 158                 case 4:
 159                         index = get_unaligned_be32(sendbuf + 18);
 160                         printf("Get flags index %#02x\n", index);
 161                         *recv_len = 22;
 162                         memset(recvbuf, '\0', *recv_len);
 163                         put_unaligned_be32(22, recvbuf +
 164                                            TPM_RESPONSE_HEADER_LENGTH);
 165                         data = recvbuf + TPM_RESPONSE_HEADER_LENGTH +
 166                                         sizeof(uint32_t);
 167                         switch (index) {
 168                         case FIRMWARE_NV_INDEX:
 169                                 break;
 170                         case KERNEL_NV_INDEX:
 171                                 /* TPM_NV_PER_PPWRITE */
 172                                 put_unaligned_be32(1, data +
 173                                         NV_DATA_PUBLIC_PERMISSIONS_OFFSET);
 174                                 break;
 175                         }
 176                         break;
 177                 case 0x11: /* TPM_CAP_NV_INDEX */
 178                         index = get_unaligned_be32(sendbuf + 18);
 179                         printf("Get cap nv index %#02x\n", index);
 180                         put_unaligned_be32(22, recvbuf +
 181                                            TPM_RESPONSE_HEADER_LENGTH);
 182                         break;
 183                 default:
 184                         printf("   ** Unknown 0x65 command type %#02x\n",
 185                                type);
 186                         return -1;
 187                 }
 188                 break;
 189         case 0xcd: /* nvwrite */
 190                 index = get_unaligned_be32(sendbuf + 10);
 191                 length = get_unaligned_be32(sendbuf + 18);
 192                 seq = index_to_seq(index);
 193                 if (seq < 0)
 194                         return -1;
 195                 printf("tpm: nvwrite index=%#02x, len=%#02x\n", index, length);
 196                 memcpy(&tpm->nvdata[seq], sendbuf + 22, length);
 197                 *recv_len = 12;
 198                 memset(recvbuf, '\0', *recv_len);
 199                 break;
 200         case 0xcf: /* nvread */
 201                 index = get_unaligned_be32(sendbuf + 10);
 202                 length = get_unaligned_be32(sendbuf + 18);
 203                 seq = index_to_seq(index);
 204                 if (seq < 0)
 205                         return -1;
 206                 printf("tpm: nvread index=%#02x, len=%#02x\n", index, length);
 207                 *recv_len = TPM_RESPONSE_HEADER_LENGTH + sizeof(uint32_t) +
 208                                         length;
 209                 memset(recvbuf, '\0', *recv_len);
 210                 put_unaligned_be32(length, recvbuf +
 211                                    TPM_RESPONSE_HEADER_LENGTH);
 212                 if (seq == NV_SEQ_KERNEL) {
 213                         struct rollback_space_kernel rsk;
 214
 215                         data = recvbuf + TPM_RESPONSE_HEADER_LENGTH +
 216                                         sizeof(uint32_t);
 217                         rsk.struct_version = 2;
 218                         rsk.uid = ROLLBACK_SPACE_KERNEL_UID;
 219                         rsk.kernel_versions = 0;
 220                         rsk.crc8 = crc8((unsigned char *)&rsk,
 221                                         offsetof(struct rollback_space_kernel,
 222                                                  crc8));
 223                         memcpy(data, &rsk, sizeof(rsk));
 224                 } else {
 225                         memcpy(recvbuf + TPM_RESPONSE_HEADER_LENGTH +
 226                                sizeof(uint32_t), &tpm->nvdata[seq], length);
 227                 }
 228                 break;
 229         case 0x14: /* tpm extend */
 230         case 0x15: /* pcr read */
 231         case 0x5d: /* force clear */
 232         case 0x6f: /* physical enable */
 233         case 0x72: /* physical set deactivated */
 234         case 0x99: /* startup */
 235         case 0x4000000a:  /* assert physical presence */
 236                 *recv_len = 12;
 237                 memset(recvbuf, '\0', *recv_len);
 238                 break;
 239         default:
 240                 printf("Unknown tpm command %02x\n", code);
 241                 return -1;
 242         }
 243
 244         return 0;
 245 }
 246
 247 static int sandbox_tpm_get_desc(struct udevice *dev, char *buf, int size)
 248 {
 249         if (size < 15)
 250                 return -ENOSPC;
 251
 252         return snprintf(buf, size, "sandbox TPM");
 253 }
 254
 255 static int sandbox_tpm_probe(struct udevice *dev)
 256 {
 257         struct tpm_state *tpm = dev_get_priv(dev);
 258
 259         memcpy(tpm, &g_state, sizeof(*tpm));
 260
 261         return 0;
 262 }
 263
 264 static int sandbox_tpm_open(struct udevice *dev)
 265 {
 266         return 0;
 267 }
 268
 269 static int sandbox_tpm_close(struct udevice *dev)
 270 {
 271         return 0;
 272 }
 273
 274 static const struct tpm_ops sandbox_tpm_ops = {
 275         .open           = sandbox_tpm_open,
 276         .close          = sandbox_tpm_close,
 277         .get_desc       = sandbox_tpm_get_desc,
 278         .xfer           = sandbox_tpm_xfer,
 279 };
 280
 281 static const struct udevice_id sandbox_tpm_ids[] = {
 282         { .compatible = "google,sandbox-tpm" },
 283         { }
 284 };
 285
 286 U_BOOT_DRIVER(sandbox_tpm) = {
 287         .name   = "sandbox_tpm",
 288         .id     = UCLASS_TPM,
 289         .of_match = sandbox_tpm_ids,
 290         .ops    = &sandbox_tpm_ops,
 291         .probe  = sandbox_tpm_probe,
 292         .priv_auto_alloc_size = sizeof(struct tpm_state),
 293 };