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 #include "trace.h"
  32
  33 /* tpm backend property */
  34
  35 static void get_tpm(Object *obj, Visitor *v, const char *name, void *opaque,
  36                     Error **errp)
  37 {
  38     DeviceState *dev = DEVICE(obj);
  39     TPMBackend **be = qdev_get_prop_ptr(dev, opaque);
  40     char *p;
  41
  42     p = g_strdup(*be ? (*be)->id : "");
  43     visit_type_str(v, name, &p, errp);
  44     g_free(p);
  45 }
  46
  47 static void set_tpm(Object *obj, Visitor *v, const char *name, void *opaque,
  48                     Error **errp)
  49 {
  50     DeviceState *dev = DEVICE(obj);
  51     Error *local_err = NULL;
  52     Property *prop = opaque;
  53     TPMBackend *s, **be = qdev_get_prop_ptr(dev, prop);
  54     char *str;
  55
  56     if (dev->realized) {
  57         qdev_prop_set_after_realize(dev, name, errp);
  58         return;
  59     }
  60
  61     visit_type_str(v, name, &str, &local_err);
  62     if (local_err) {
  63         error_propagate(errp, local_err);
  64         return;
  65     }
  66
  67     s = qemu_find_tpm_be(str);
  68     if (s == NULL) {
  69         error_setg(errp, "Property '%s.%s' can't find value '%s'",
  70                    object_get_typename(obj), prop->name, str);
  71     } else if (tpm_backend_init(s, TPM_IF(obj), errp) == 0) {
  72         *be = s; /* weak reference, avoid cyclic ref */
  73     }
  74     g_free(str);
  75 }
  76
  77 static void release_tpm(Object *obj, const char *name, void *opaque)
  78 {
  79     DeviceState *dev = DEVICE(obj);
  80     Property *prop = opaque;
  81     TPMBackend **be = qdev_get_prop_ptr(dev, prop);
  82
  83     if (*be) {
  84         tpm_backend_reset(*be);
  85     }
  86 }
  87
  88 const PropertyInfo qdev_prop_tpm = {
  89     .name  = "str",
  90     .description = "ID of a tpm to use as a backend",
  91     .get   = get_tpm,
  92     .set   = set_tpm,
  93     .release = release_tpm,
  94 };
  95
  96 /*
  97  * Write an error message in the given output buffer.
  98  */
  99 void tpm_util_write_fatal_error_response(uint8_t *out, uint32_t out_len)
 100 {
 101     if (out_len >= sizeof(struct tpm_resp_hdr)) {
 102         tpm_cmd_set_tag(out, TPM_TAG_RSP_COMMAND);
 103         tpm_cmd_set_size(out, sizeof(struct tpm_resp_hdr));
 104         tpm_cmd_set_error(out, TPM_FAIL);
 105     }
 106 }
 107
 108 bool tpm_util_is_selftest(const uint8_t *in, uint32_t in_len)
 109 {
 110     if (in_len >= sizeof(struct tpm_req_hdr)) {
 111         return tpm_cmd_get_ordinal(in) == TPM_ORD_ContinueSelfTest;
 112     }
 113
 114     return false;
 115 }
 116
 117 /*
 118  * Send request to a TPM device. We expect a response within one second.
 119  */
 120 static int tpm_util_request(int fd,
 121                             const void *request,
 122                             size_t requestlen,
 123                             void *response,
 124                             size_t responselen)
 125 {
 126     fd_set readfds;
 127     int n;
 128     struct timeval tv = {
 129         .tv_sec = 1,
 130         .tv_usec = 0,
 131     };
 132
 133     n = write(fd, request, requestlen);
 134     if (n < 0) {
 135         return -errno;
 136     }
 137     if (n != requestlen) {
 138         return -EFAULT;
 139     }
 140
 141     FD_ZERO(&readfds);
 142     FD_SET(fd, &readfds);
 143
 144     /* wait for a second */
 145     n = select(fd + 1, &readfds, NULL, NULL, &tv);
 146     if (n != 1) {
 147         return -errno;
 148     }
 149
 150     n = read(fd, response, responselen);
 151     if (n < sizeof(struct tpm_resp_hdr)) {
 152         return -EFAULT;
 153     }
 154
 155     /* check the header */
 156     if (tpm_cmd_get_size(response) != n) {
 157         return -EMSGSIZE;
 158     }
 159
 160     return 0;
 161 }
 162
 163 /*
 164  * A basic test of a TPM device. We expect a well formatted response header
 165  * (error response is fine).
 166  */
 167 static int tpm_util_test(int fd,
 168                          const void *request,
 169                          size_t requestlen,
 170                          uint16_t *return_tag)
 171 {
 172     char buf[1024];
 173     ssize_t ret;
 174
 175     ret = tpm_util_request(fd, request, requestlen,
 176                            buf, sizeof(buf));
 177     if (ret < 0) {
 178         return ret;
 179     }
 180
 181     *return_tag = tpm_cmd_get_tag(buf);
 182
 183     return 0;
 184 }
 185
 186 /*
 187  * Probe for the TPM device in the back
 188  * Returns 0 on success with the version of the probed TPM set, 1 on failure.
 189  */
 190 int tpm_util_test_tpmdev(int tpm_fd, TPMVersion *tpm_version)
 191 {
 192     /*
 193      * Sending a TPM1.2 command to a TPM2 should return a TPM1.2
 194      * header (tag = 0xc4) and error code (TPM_BADTAG = 0x1e)
 195      *
 196      * Sending a TPM2 command to a TPM 2 will give a TPM 2 tag in the
 197      * header.
 198      * Sending a TPM2 command to a TPM 1.2 will give a TPM 1.2 tag
 199      * in the header and an error code.
 200      */
 201     const struct tpm_req_hdr test_req = {
 202         .tag = cpu_to_be16(TPM_TAG_RQU_COMMAND),
 203         .len = cpu_to_be32(sizeof(test_req)),
 204         .ordinal = cpu_to_be32(TPM_ORD_GetTicks),
 205     };
 206
 207     const struct tpm_req_hdr test_req_tpm2 = {
 208         .tag = cpu_to_be16(TPM2_ST_NO_SESSIONS),
 209         .len = cpu_to_be32(sizeof(test_req_tpm2)),
 210         .ordinal = cpu_to_be32(TPM2_CC_ReadClock),
 211     };
 212     uint16_t return_tag;
 213     int ret;
 214
 215     /* Send TPM 2 command */
 216     ret = tpm_util_test(tpm_fd, &test_req_tpm2,
 217                         sizeof(test_req_tpm2), &return_tag);
 218     /* TPM 2 would respond with a tag of TPM2_ST_NO_SESSIONS */
 219     if (!ret && return_tag == TPM2_ST_NO_SESSIONS) {
 220         *tpm_version = TPM_VERSION_2_0;
 221         return 0;
 222     }
 223
 224     /* Send TPM 1.2 command */
 225     ret = tpm_util_test(tpm_fd, &test_req,
 226                         sizeof(test_req), &return_tag);
 227     if (!ret && return_tag == TPM_TAG_RSP_COMMAND) {
 228         *tpm_version = TPM_VERSION_1_2;
 229         /* this is a TPM 1.2 */
 230         return 0;
 231     }
 232
 233     *tpm_version = TPM_VERSION_UNSPEC;
 234
 235     return 1;
 236 }
 237
 238 int tpm_util_get_buffer_size(int tpm_fd, TPMVersion tpm_version,
 239                              size_t *buffersize)
 240 {
 241     int ret;
 242
 243     switch (tpm_version) {
 244     case TPM_VERSION_1_2: {
 245         const struct tpm_req_get_buffer_size {
 246             struct tpm_req_hdr hdr;
 247             uint32_t capability;
 248             uint32_t len;
 249             uint32_t subcap;
 250         } QEMU_PACKED tpm_get_buffer_size = {
 251             .hdr = {
 252                 .tag = cpu_to_be16(TPM_TAG_RQU_COMMAND),
 253                 .len = cpu_to_be32(sizeof(tpm_get_buffer_size)),
 254                 .ordinal = cpu_to_be32(TPM_ORD_GetCapability),
 255             },
 256             .capability = cpu_to_be32(TPM_CAP_PROPERTY),
 257             .len = cpu_to_be32(sizeof(uint32_t)),
 258             .subcap = cpu_to_be32(TPM_CAP_PROP_INPUT_BUFFER),
 259         };
 260         struct tpm_resp_get_buffer_size {
 261             struct tpm_resp_hdr hdr;
 262             uint32_t len;
 263             uint32_t buffersize;
 264         } QEMU_PACKED tpm_resp;
 265
 266         ret = tpm_util_request(tpm_fd, &tpm_get_buffer_size,
 267                                sizeof(tpm_get_buffer_size),
 268                                &tpm_resp, sizeof(tpm_resp));
 269         if (ret < 0) {
 270             return ret;
 271         }
 272
 273         if (be32_to_cpu(tpm_resp.hdr.len) != sizeof(tpm_resp) ||
 274             be32_to_cpu(tpm_resp.len) != sizeof(uint32_t)) {
 275             trace_tpm_util_get_buffer_size_hdr_len(
 276                 be32_to_cpu(tpm_resp.hdr.len),
 277                 sizeof(tpm_resp));
 278             trace_tpm_util_get_buffer_size_len(be32_to_cpu(tpm_resp.len),
 279                                                sizeof(uint32_t));
 280             error_report("tpm_util: Got unexpected response to "
 281                          "TPM_GetCapability; errcode: 0x%x",
 282                          be32_to_cpu(tpm_resp.hdr.errcode));
 283             return -EFAULT;
 284         }
 285         *buffersize = be32_to_cpu(tpm_resp.buffersize);
 286         break;
 287     }
 288     case TPM_VERSION_2_0: {
 289         const struct tpm2_req_get_buffer_size {
 290             struct tpm_req_hdr hdr;
 291             uint32_t capability;
 292             uint32_t property;
 293             uint32_t count;
 294         } QEMU_PACKED tpm2_get_buffer_size = {
 295             .hdr = {
 296                 .tag = cpu_to_be16(TPM2_ST_NO_SESSIONS),
 297                 .len = cpu_to_be32(sizeof(tpm2_get_buffer_size)),
 298                 .ordinal = cpu_to_be32(TPM2_CC_GetCapability),
 299             },
 300             .capability = cpu_to_be32(TPM2_CAP_TPM_PROPERTIES),
 301             .property = cpu_to_be32(TPM2_PT_MAX_COMMAND_SIZE),
 302             .count = cpu_to_be32(2), /* also get TPM2_PT_MAX_RESPONSE_SIZE */
 303         };
 304         struct tpm2_resp_get_buffer_size {
 305             struct tpm_resp_hdr hdr;
 306             uint8_t more;
 307             uint32_t capability;
 308             uint32_t count;
 309             uint32_t property1;
 310             uint32_t value1;
 311             uint32_t property2;
 312             uint32_t value2;
 313         } QEMU_PACKED tpm2_resp;
 314
 315         ret = tpm_util_request(tpm_fd, &tpm2_get_buffer_size,
 316                                sizeof(tpm2_get_buffer_size),
 317                                &tpm2_resp, sizeof(tpm2_resp));
 318         if (ret < 0) {
 319             return ret;
 320         }
 321
 322         if (be32_to_cpu(tpm2_resp.hdr.len) != sizeof(tpm2_resp) ||
 323             be32_to_cpu(tpm2_resp.count) != 2) {
 324             trace_tpm_util_get_buffer_size_hdr_len2(
 325                 be32_to_cpu(tpm2_resp.hdr.len),
 326                 sizeof(tpm2_resp));
 327             trace_tpm_util_get_buffer_size_len2(
 328                 be32_to_cpu(tpm2_resp.count), 2);
 329             error_report("tpm_util: Got unexpected response to "
 330                          "TPM2_GetCapability; errcode: 0x%x",
 331                          be32_to_cpu(tpm2_resp.hdr.errcode));
 332             return -EFAULT;
 333         }
 334         *buffersize = MAX(be32_to_cpu(tpm2_resp.value1),
 335                           be32_to_cpu(tpm2_resp.value2));
 336         break;
 337     }
 338     case TPM_VERSION_UNSPEC:
 339         return -EFAULT;
 340     }
 341
 342     trace_tpm_util_get_buffer_size(*buffersize);
 343
 344     return 0;
 345 }
 346
 347 void tpm_sized_buffer_reset(TPMSizedBuffer *tsb)
 348 {
 349     g_free(tsb->buffer);
 350     tsb->buffer = NULL;
 351     tsb->size = 0;
 352 }