backends/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 2.1 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_int.h"
  27 #include "exec/memory.h"
  28 #include "hw/qdev-properties.h"
  29 #include "sysemu/tpm_backend.h"
  30 #include "sysemu/tpm_util.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     TPMBackend **be = object_field_prop_ptr(obj, opaque);
  39     char *p;
  40
  41     p = g_strdup(*be ? (*be)->id : "");
  42     visit_type_str(v, name, &p, errp);
  43     g_free(p);
  44 }
  45
  46 static void set_tpm(Object *obj, Visitor *v, const char *name, void *opaque,
  47                     Error **errp)
  48 {
  49     Property *prop = opaque;
  50     TPMBackend *s, **be = object_field_prop_ptr(obj, prop);
  51     char *str;
  52
  53     if (!visit_type_str(v, name, &str, errp)) {
  54         return;
  55     }
  56
  57     s = qemu_find_tpm_be(str);
  58     if (s == NULL) {
  59         error_setg(errp, "Property '%s.%s' can't find value '%s'",
  60                    object_get_typename(obj), name, str);
  61     } else if (tpm_backend_init(s, TPM_IF(obj), errp) == 0) {
  62         *be = s; /* weak reference, avoid cyclic ref */
  63     }
  64     g_free(str);
  65 }
  66
  67 static void release_tpm(Object *obj, const char *name, void *opaque)
  68 {
  69     Property *prop = opaque;
  70     TPMBackend **be = object_field_prop_ptr(obj, prop);
  71
  72     if (*be) {
  73         tpm_backend_reset(*be);
  74     }
  75 }
  76
  77 const PropertyInfo qdev_prop_tpm = {
  78     .name  = "str",
  79     .description = "ID of a tpm to use as a backend",
  80     .get   = get_tpm,
  81     .set   = set_tpm,
  82     .release = release_tpm,
  83 };
  84
  85 /*
  86  * Write an error message in the given output buffer.
  87  */
  88 void tpm_util_write_fatal_error_response(uint8_t *out, uint32_t out_len)
  89 {
  90     if (out_len >= sizeof(struct tpm_resp_hdr)) {
  91         tpm_cmd_set_tag(out, TPM_TAG_RSP_COMMAND);
  92         tpm_cmd_set_size(out, sizeof(struct tpm_resp_hdr));
  93         tpm_cmd_set_error(out, TPM_FAIL);
  94     }
  95 }
  96
  97 bool tpm_util_is_selftest(const uint8_t *in, uint32_t in_len)
  98 {
  99     if (in_len >= sizeof(struct tpm_req_hdr)) {
 100         return tpm_cmd_get_ordinal(in) == TPM_ORD_ContinueSelfTest;
 101     }
 102
 103     return false;
 104 }
 105
 106 /*
 107  * Send request to a TPM device. We expect a response within one second.
 108  */
 109 static int tpm_util_request(int fd,
 110                             const void *request,
 111                             size_t requestlen,
 112                             void *response,
 113                             size_t responselen)
 114 {
 115     GPollFD fds[1] = { {.fd = fd, .events = G_IO_IN } };
 116     int n;
 117
 118     n = write(fd, request, requestlen);
 119     if (n < 0) {
 120         return -errno;
 121     }
 122     if (n != requestlen) {
 123         return -EFAULT;
 124     }
 125
 126     /* wait for a second */
 127     n = RETRY_ON_EINTR(g_poll(fds, 1, 1000));
 128     if (n != 1) {
 129         return -errno;
 130     }
 131
 132     n = read(fd, response, responselen);
 133     if (n < sizeof(struct tpm_resp_hdr)) {
 134         return -EFAULT;
 135     }
 136
 137     /* check the header */
 138     if (tpm_cmd_get_size(response) != n) {
 139         return -EMSGSIZE;
 140     }
 141
 142     return 0;
 143 }
 144
 145 /*
 146  * A basic test of a TPM device. We expect a well formatted response header
 147  * (error response is fine).
 148  */
 149 static int tpm_util_test(int fd,
 150                          const void *request,
 151                          size_t requestlen,
 152                          uint16_t *return_tag)
 153 {
 154     char buf[1024];
 155     ssize_t ret;
 156
 157     ret = tpm_util_request(fd, request, requestlen,
 158                            buf, sizeof(buf));
 159     if (ret < 0) {
 160         return ret;
 161     }
 162
 163     *return_tag = tpm_cmd_get_tag(buf);
 164
 165     return 0;
 166 }
 167
 168 /*
 169  * Probe for the TPM device in the back
 170  * Returns 0 on success with the version of the probed TPM set, 1 on failure.
 171  */
 172 int tpm_util_test_tpmdev(int tpm_fd, TPMVersion *tpm_version)
 173 {
 174     /*
 175      * Sending a TPM1.2 command to a TPM2 should return a TPM1.2
 176      * header (tag = 0xc4) and error code (TPM_BADTAG = 0x1e)
 177      *
 178      * Sending a TPM2 command to a TPM 2 will give a TPM 2 tag in the
 179      * header.
 180      * Sending a TPM2 command to a TPM 1.2 will give a TPM 1.2 tag
 181      * in the header and an error code.
 182      */
 183     const struct tpm_req_hdr test_req = {
 184         .tag = cpu_to_be16(TPM_TAG_RQU_COMMAND),
 185         .len = cpu_to_be32(sizeof(test_req)),
 186         .ordinal = cpu_to_be32(TPM_ORD_GetTicks),
 187     };
 188
 189     const struct tpm_req_hdr test_req_tpm2 = {
 190         .tag = cpu_to_be16(TPM2_ST_NO_SESSIONS),
 191         .len = cpu_to_be32(sizeof(test_req_tpm2)),
 192         .ordinal = cpu_to_be32(TPM2_CC_ReadClock),
 193     };
 194     uint16_t return_tag;
 195     int ret;
 196
 197     /* Send TPM 2 command */
 198     ret = tpm_util_test(tpm_fd, &test_req_tpm2,
 199                         sizeof(test_req_tpm2), &return_tag);
 200     /* TPM 2 would respond with a tag of TPM2_ST_NO_SESSIONS */
 201     if (!ret && return_tag == TPM2_ST_NO_SESSIONS) {
 202         *tpm_version = TPM_VERSION_2_0;
 203         return 0;
 204     }
 205
 206     /* Send TPM 1.2 command */
 207     ret = tpm_util_test(tpm_fd, &test_req,
 208                         sizeof(test_req), &return_tag);
 209     if (!ret && return_tag == TPM_TAG_RSP_COMMAND) {
 210         *tpm_version = TPM_VERSION_1_2;
 211         /* this is a TPM 1.2 */
 212         return 0;
 213     }
 214
 215     *tpm_version = TPM_VERSION_UNSPEC;
 216
 217     return 1;
 218 }
 219
 220 int tpm_util_get_buffer_size(int tpm_fd, TPMVersion tpm_version,
 221                              size_t *buffersize)
 222 {
 223     int ret;
 224
 225     switch (tpm_version) {
 226     case TPM_VERSION_1_2: {
 227         const struct tpm_req_get_buffer_size {
 228             struct tpm_req_hdr hdr;
 229             uint32_t capability;
 230             uint32_t len;
 231             uint32_t subcap;
 232         } QEMU_PACKED tpm_get_buffer_size = {
 233             .hdr = {
 234                 .tag = cpu_to_be16(TPM_TAG_RQU_COMMAND),
 235                 .len = cpu_to_be32(sizeof(tpm_get_buffer_size)),
 236                 .ordinal = cpu_to_be32(TPM_ORD_GetCapability),
 237             },
 238             .capability = cpu_to_be32(TPM_CAP_PROPERTY),
 239             .len = cpu_to_be32(sizeof(uint32_t)),
 240             .subcap = cpu_to_be32(TPM_CAP_PROP_INPUT_BUFFER),
 241         };
 242         struct tpm_resp_get_buffer_size {
 243             struct tpm_resp_hdr hdr;
 244             uint32_t len;
 245             uint32_t buffersize;
 246         } QEMU_PACKED tpm_resp;
 247
 248         ret = tpm_util_request(tpm_fd, &tpm_get_buffer_size,
 249                                sizeof(tpm_get_buffer_size),
 250                                &tpm_resp, sizeof(tpm_resp));
 251         if (ret < 0) {
 252             return ret;
 253         }
 254
 255         if (be32_to_cpu(tpm_resp.hdr.len) != sizeof(tpm_resp) ||
 256             be32_to_cpu(tpm_resp.len) != sizeof(uint32_t)) {
 257             trace_tpm_util_get_buffer_size_hdr_len(
 258                 be32_to_cpu(tpm_resp.hdr.len),
 259                 sizeof(tpm_resp));
 260             trace_tpm_util_get_buffer_size_len(be32_to_cpu(tpm_resp.len),
 261                                                sizeof(uint32_t));
 262             error_report("tpm_util: Got unexpected response to "
 263                          "TPM_GetCapability; errcode: 0x%x",
 264                          be32_to_cpu(tpm_resp.hdr.errcode));
 265             return -EFAULT;
 266         }
 267         *buffersize = be32_to_cpu(tpm_resp.buffersize);
 268         break;
 269     }
 270     case TPM_VERSION_2_0: {
 271         const struct tpm2_req_get_buffer_size {
 272             struct tpm_req_hdr hdr;
 273             uint32_t capability;
 274             uint32_t property;
 275             uint32_t count;
 276         } QEMU_PACKED tpm2_get_buffer_size = {
 277             .hdr = {
 278                 .tag = cpu_to_be16(TPM2_ST_NO_SESSIONS),
 279                 .len = cpu_to_be32(sizeof(tpm2_get_buffer_size)),
 280                 .ordinal = cpu_to_be32(TPM2_CC_GetCapability),
 281             },
 282             .capability = cpu_to_be32(TPM2_CAP_TPM_PROPERTIES),
 283             .property = cpu_to_be32(TPM2_PT_MAX_COMMAND_SIZE),
 284             .count = cpu_to_be32(2), /* also get TPM2_PT_MAX_RESPONSE_SIZE */
 285         };
 286         struct tpm2_resp_get_buffer_size {
 287             struct tpm_resp_hdr hdr;
 288             uint8_t more;
 289             uint32_t capability;
 290             uint32_t count;
 291             uint32_t property1;
 292             uint32_t value1;
 293             uint32_t property2;
 294             uint32_t value2;
 295         } QEMU_PACKED tpm2_resp;
 296
 297         ret = tpm_util_request(tpm_fd, &tpm2_get_buffer_size,
 298                                sizeof(tpm2_get_buffer_size),
 299                                &tpm2_resp, sizeof(tpm2_resp));
 300         if (ret < 0) {
 301             return ret;
 302         }
 303
 304         if (be32_to_cpu(tpm2_resp.hdr.len) != sizeof(tpm2_resp) ||
 305             be32_to_cpu(tpm2_resp.count) != 2) {
 306             trace_tpm_util_get_buffer_size_hdr_len2(
 307                 be32_to_cpu(tpm2_resp.hdr.len),
 308                 sizeof(tpm2_resp));
 309             trace_tpm_util_get_buffer_size_len2(
 310                 be32_to_cpu(tpm2_resp.count), 2);
 311             error_report("tpm_util: Got unexpected response to "
 312                          "TPM2_GetCapability; errcode: 0x%x",
 313                          be32_to_cpu(tpm2_resp.hdr.errcode));
 314             return -EFAULT;
 315         }
 316         *buffersize = MAX(be32_to_cpu(tpm2_resp.value1),
 317                           be32_to_cpu(tpm2_resp.value2));
 318         break;
 319     }
 320     case TPM_VERSION_UNSPEC:
 321         return -EFAULT;
 322     }
 323
 324     trace_tpm_util_get_buffer_size(*buffersize);
 325
 326     return 0;
 327 }
 328
 329 void tpm_sized_buffer_reset(TPMSizedBuffer *tsb)
 330 {
 331     g_free(tsb->buffer);
 332     tsb->buffer = NULL;
 333     tsb->size = 0;
 334 }
 335
 336 void tpm_util_show_buffer(const unsigned char *buffer,
 337                           size_t buffer_size, const char *string)
 338 {
 339     size_t len, i;
 340     char *line_buffer, *p;
 341
 342     if (!trace_event_get_state_backends(TRACE_TPM_UTIL_SHOW_BUFFER)) {
 343         return;
 344     }
 345     len = MIN(tpm_cmd_get_size(buffer), buffer_size);
 346
 347     /*
 348      * allocate enough room for 3 chars per buffer entry plus a
 349      * newline after every 16 chars and a final null terminator.
 350      */
 351     line_buffer = g_malloc(len * 3 + (len / 16) + 1);
 352
 353     for (i = 0, p = line_buffer; i < len; i++) {
 354         if (i && !(i % 16)) {
 355             p += sprintf(p, "\n");
 356         }
 357         p += sprintf(p, "%.2X ", buffer[i]);
 358     }
 359     trace_tpm_util_show_buffer(string, len, line_buffer);
 360
 361     g_free(line_buffer);
 362 }