hw/tpm/tpm_util.c

   1 /*
   2  * TPM utility functions
   3  *
   4  *  Copyright (c) 2010 - 2015 IBM Corporation
   5  *  Authors:
   6  *    Stefan Berger <stefanb@us.ibm.com>
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2 of the License, or (at your option) any later version.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, see <http://www.gnu.org/licenses/>
  20  */
  21
  22 #include "qemu/osdep.h"
  23 #include "qemu/error-report.h"
  24 #include "qapi/error.h"
  25 #include "qapi/visitor.h"
  26 #include "tpm_util.h"
  27 #include "tpm_int.h"
  28 #include "exec/memory.h"
  29 #include "sysemu/tpm_backend.h"
  30 #include "hw/qdev.h"
  31
  32 #define DEBUG_TPM 0
  33
  34 #define DPRINTF(fmt, ...) do { \
  35     if (DEBUG_TPM) { \
  36         fprintf(stderr, "tpm-util:"fmt"\n", ## __VA_ARGS__); \
  37     } \
  38 } while (0)
  39
  40 /* tpm backend property */
  41
  42 static void get_tpm(Object *obj, Visitor *v, const char *name, void *opaque,
  43                     Error **errp)
  44 {
  45     DeviceState *dev = DEVICE(obj);
  46     TPMBackend **be = qdev_get_prop_ptr(dev, opaque);
  47     char *p;
  48
  49     p = g_strdup(*be ? (*be)->id : "");
  50     visit_type_str(v, name, &p, errp);
  51     g_free(p);
  52 }
  53
  54 static void set_tpm(Object *obj, Visitor *v, const char *name, void *opaque,
  55                     Error **errp)
  56 {
  57     DeviceState *dev = DEVICE(obj);
  58     Error *local_err = NULL;
  59     Property *prop = opaque;
  60     TPMBackend *s, **be = qdev_get_prop_ptr(dev, prop);
  61     char *str;
  62
  63     if (dev->realized) {
  64         qdev_prop_set_after_realize(dev, name, errp);
  65         return;
  66     }
  67
  68     visit_type_str(v, name, &str, &local_err);
  69     if (local_err) {
  70         error_propagate(errp, local_err);
  71         return;
  72     }
  73
  74     s = qemu_find_tpm_be(str);
  75     if (s == NULL) {
  76         error_setg(errp, "Property '%s.%s' can't find value '%s'",
  77                    object_get_typename(obj), prop->name, str);
  78     } else if (tpm_backend_init(s, TPM_IF(obj), errp) == 0) {
  79         *be = s; /* weak reference, avoid cyclic ref */
  80     }
  81     g_free(str);
  82 }
  83
  84 static void release_tpm(Object *obj, const char *name, void *opaque)
  85 {
  86     DeviceState *dev = DEVICE(obj);
  87     Property *prop = opaque;
  88     TPMBackend **be = qdev_get_prop_ptr(dev, prop);
  89
  90     if (*be) {
  91         tpm_backend_reset(*be);
  92     }
  93 }
  94
  95 const PropertyInfo qdev_prop_tpm = {
  96     .name  = "str",
  97     .description = "ID of a tpm to use as a backend",
  98     .get   = get_tpm,
  99     .set   = set_tpm,
 100     .release = release_tpm,
 101 };
 102
 103 /*
 104  * Write an error message in the given output buffer.
 105  */
 106 void tpm_util_write_fatal_error_response(uint8_t *out, uint32_t out_len)
 107 {
 108     if (out_len >= sizeof(struct tpm_resp_hdr)) {
 109         stw_be_p(out, TPM_TAG_RSP_COMMAND);
 110         stl_be_p(out + 2, sizeof(struct tpm_resp_hdr));
 111         stl_be_p(out + 6, TPM_FAIL);
 112     }
 113 }
 114
 115 bool tpm_util_is_selftest(const uint8_t *in, uint32_t in_len)
 116 {
 117     if (in_len >= sizeof(struct tpm_req_hdr)) {
 118         return tpm_cmd_get_ordinal(in) == TPM_ORD_ContinueSelfTest;
 119     }
 120
 121     return false;
 122 }
 123
 124 /*
 125  * Send request to a TPM device. We expect a response within one second.
 126  */
 127 static int tpm_util_request(int fd,
 128                             const void *request,
 129                             size_t requestlen,
 130                             void *response,
 131                             size_t responselen)
 132 {
 133     fd_set readfds;
 134     int n;
 135     struct timeval tv = {
 136         .tv_sec = 1,
 137         .tv_usec = 0,
 138     };
 139
 140     n = write(fd, request, requestlen);
 141     if (n < 0) {
 142         return -errno;
 143     }
 144     if (n != requestlen) {
 145         return -EFAULT;
 146     }
 147
 148     FD_ZERO(&readfds);
 149     FD_SET(fd, &readfds);
 150
 151     /* wait for a second */
 152     n = select(fd + 1, &readfds, NULL, NULL, &tv);
 153     if (n != 1) {
 154         return -errno;
 155     }
 156
 157     n = read(fd, response, responselen);
 158     if (n < sizeof(struct tpm_resp_hdr)) {
 159         return -EFAULT;
 160     }
 161
 162     /* check the header */
 163     if (tpm_cmd_get_size(response) != n) {
 164         return -EMSGSIZE;
 165     }
 166
 167     return 0;
 168 }
 169
 170 /*
 171  * A basic test of a TPM device. We expect a well formatted response header
 172  * (error response is fine).
 173  */
 174 static int tpm_util_test(int fd,
 175                          const void *request,
 176                          size_t requestlen,
 177                          uint16_t *return_tag)
 178 {
 179     char buf[1024];
 180     ssize_t ret;
 181
 182     ret = tpm_util_request(fd, request, requestlen,
 183                            buf, sizeof(buf));
 184     if (ret < 0) {
 185         return ret;
 186     }
 187
 188     *return_tag = tpm_cmd_get_tag(buf);
 189
 190     return 0;
 191 }
 192
 193 /*
 194  * Probe for the TPM device in the back
 195  * Returns 0 on success with the version of the probed TPM set, 1 on failure.
 196  */
 197 int tpm_util_test_tpmdev(int tpm_fd, TPMVersion *tpm_version)
 198 {
 199     /*
 200      * Sending a TPM1.2 command to a TPM2 should return a TPM1.2
 201      * header (tag = 0xc4) and error code (TPM_BADTAG = 0x1e)
 202      *
 203      * Sending a TPM2 command to a TPM 2 will give a TPM 2 tag in the
 204      * header.
 205      * Sending a TPM2 command to a TPM 1.2 will give a TPM 1.2 tag
 206      * in the header and an error code.
 207      */
 208     const struct tpm_req_hdr test_req = {
 209         .tag = cpu_to_be16(TPM_TAG_RQU_COMMAND),
 210         .len = cpu_to_be32(sizeof(test_req)),
 211         .ordinal = cpu_to_be32(TPM_ORD_GetTicks),
 212     };
 213
 214     const struct tpm_req_hdr test_req_tpm2 = {
 215         .tag = cpu_to_be16(TPM2_ST_NO_SESSIONS),
 216         .len = cpu_to_be32(sizeof(test_req_tpm2)),
 217         .ordinal = cpu_to_be32(TPM2_CC_ReadClock),
 218     };
 219     uint16_t return_tag;
 220     int ret;
 221
 222     /* Send TPM 2 command */
 223     ret = tpm_util_test(tpm_fd, &test_req_tpm2,
 224                         sizeof(test_req_tpm2), &return_tag);
 225     /* TPM 2 would respond with a tag of TPM2_ST_NO_SESSIONS */
 226     if (!ret && return_tag == TPM2_ST_NO_SESSIONS) {
 227         *tpm_version = TPM_VERSION_2_0;
 228         return 0;
 229     }
 230
 231     /* Send TPM 1.2 command */
 232     ret = tpm_util_test(tpm_fd, &test_req,
 233                         sizeof(test_req), &return_tag);
 234     if (!ret && return_tag == TPM_TAG_RSP_COMMAND) {
 235         *tpm_version = TPM_VERSION_1_2;
 236         /* this is a TPM 1.2 */
 237         return 0;
 238     }
 239
 240     *tpm_version = TPM_VERSION_UNSPEC;
 241
 242     return 1;
 243 }
 244
 245 int tpm_util_get_buffer_size(int tpm_fd, TPMVersion tpm_version,
 246                              size_t *buffersize)
 247 {
 248     int ret;
 249
 250     switch (tpm_version) {
 251     case TPM_VERSION_1_2: {
 252         const struct tpm_req_get_buffer_size {
 253             struct tpm_req_hdr hdr;
 254             uint32_t capability;
 255             uint32_t len;
 256             uint32_t subcap;
 257         } QEMU_PACKED tpm_get_buffer_size = {
 258             .hdr = {
 259                 .tag = cpu_to_be16(TPM_TAG_RQU_COMMAND),
 260                 .len = cpu_to_be32(sizeof(tpm_get_buffer_size)),
 261                 .ordinal = cpu_to_be32(TPM_ORD_GetCapability),
 262             },
 263             .capability = cpu_to_be32(TPM_CAP_PROPERTY),
 264             .len = cpu_to_be32(sizeof(uint32_t)),
 265             .subcap = cpu_to_be32(TPM_CAP_PROP_INPUT_BUFFER),
 266         };
 267         struct tpm_resp_get_buffer_size {
 268             struct tpm_resp_hdr hdr;
 269             uint32_t len;
 270             uint32_t buffersize;
 271         } QEMU_PACKED tpm_resp;
 272
 273         ret = tpm_util_request(tpm_fd, &tpm_get_buffer_size,
 274                                sizeof(tpm_get_buffer_size),
 275                                &tpm_resp, sizeof(tpm_resp));
 276         if (ret < 0) {
 277             return ret;
 278         }
 279
 280         if (be32_to_cpu(tpm_resp.hdr.len) != sizeof(tpm_resp) ||
 281             be32_to_cpu(tpm_resp.len) != sizeof(uint32_t)) {
 282             DPRINTF("tpm_resp->hdr.len = %u, expected = %zu\n",
 283                     be32_to_cpu(tpm_resp.hdr.len), sizeof(tpm_resp));
 284             DPRINTF("tpm_resp->len = %u, expected = %zu\n",
 285                     be32_to_cpu(tpm_resp.len), sizeof(uint32_t));
 286             error_report("tpm_util: Got unexpected response to "
 287                          "TPM_GetCapability; errcode: 0x%x",
 288                          be32_to_cpu(tpm_resp.hdr.errcode));
 289             return -EFAULT;
 290         }
 291         *buffersize = be32_to_cpu(tpm_resp.buffersize);
 292         break;
 293     }
 294     case TPM_VERSION_2_0: {
 295         const struct tpm2_req_get_buffer_size {
 296             struct tpm_req_hdr hdr;
 297             uint32_t capability;
 298             uint32_t property;
 299             uint32_t count;
 300         } QEMU_PACKED tpm2_get_buffer_size = {
 301             .hdr = {
 302                 .tag = cpu_to_be16(TPM2_ST_NO_SESSIONS),
 303                 .len = cpu_to_be32(sizeof(tpm2_get_buffer_size)),
 304                 .ordinal = cpu_to_be32(TPM2_CC_GetCapability),
 305             },
 306             .capability = cpu_to_be32(TPM2_CAP_TPM_PROPERTIES),
 307             .property = cpu_to_be32(TPM2_PT_MAX_COMMAND_SIZE),
 308             .count = cpu_to_be32(2), /* also get TPM2_PT_MAX_RESPONSE_SIZE */
 309         };
 310         struct tpm2_resp_get_buffer_size {
 311             struct tpm_resp_hdr hdr;
 312             uint8_t more;
 313             uint32_t capability;
 314             uint32_t count;
 315             uint32_t property1;
 316             uint32_t value1;
 317             uint32_t property2;
 318             uint32_t value2;
 319         } QEMU_PACKED tpm2_resp;
 320
 321         ret = tpm_util_request(tpm_fd, &tpm2_get_buffer_size,
 322                                sizeof(tpm2_get_buffer_size),
 323                                &tpm2_resp, sizeof(tpm2_resp));
 324         if (ret < 0) {
 325             return ret;
 326         }
 327
 328         if (be32_to_cpu(tpm2_resp.hdr.len) != sizeof(tpm2_resp) ||
 329             be32_to_cpu(tpm2_resp.count) != 2) {
 330             DPRINTF("tpm2_resp->hdr.len = %u, expected = %zu\n",
 331                     be32_to_cpu(tpm2_resp.hdr.len), sizeof(tpm2_resp));
 332             DPRINTF("tpm2_resp->len = %u, expected = %u\n",
 333                     be32_to_cpu(tpm2_resp.count), 2);
 334             error_report("tpm_util: Got unexpected response to "
 335                          "TPM2_GetCapability; errcode: 0x%x",
 336                          be32_to_cpu(tpm2_resp.hdr.errcode));
 337             return -EFAULT;
 338         }
 339         *buffersize = MAX(be32_to_cpu(tpm2_resp.value1),
 340                           be32_to_cpu(tpm2_resp.value2));
 341         break;
 342     }
 343     case TPM_VERSION_UNSPEC:
 344         return -EFAULT;
 345     }
 346
 347     DPRINTF("buffersize of device: %zu\n", *buffersize);
 348
 349     return 0;
 350 }
 351
 352 void tpm_sized_buffer_reset(TPMSizedBuffer *tsb)
 353 {
 354     g_free(tsb->buffer);
 355     tsb->buffer = NULL;
 356     tsb->size = 0;
 357 }