drivers/char/tpm/xen-tpmfront.c

   1 /*
   2  * Implementation of the Xen vTPM device frontend
   3  *
   4  * Author:  Daniel De Graaf <dgdegra@tycho.nsa.gov>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2,
   8  * as published by the Free Software Foundation.
   9  */
  10 #include <linux/errno.h>
  11 #include <linux/err.h>
  12 #include <linux/interrupt.h>
  13 #include <xen/xen.h>
  14 #include <xen/events.h>
  15 #include <xen/interface/io/tpmif.h>
  16 #include <xen/grant_table.h>
  17 #include <xen/xenbus.h>
  18 #include <xen/page.h>
  19 #include "tpm.h"
  20 #include <xen/platform_pci.h>
  21
  22 struct tpm_private {
  23         struct tpm_chip *chip;
  24         struct xenbus_device *dev;
  25
  26         struct vtpm_shared_page *shr;
  27
  28         unsigned int evtchn;
  29         int ring_ref;
  30         domid_t backend_id;
  31 };
  32
  33 enum status_bits {
  34         VTPM_STATUS_RUNNING  = 0x1,
  35         VTPM_STATUS_IDLE     = 0x2,
  36         VTPM_STATUS_RESULT   = 0x4,
  37         VTPM_STATUS_CANCELED = 0x8,
  38 };
  39
  40 static u8 vtpm_status(struct tpm_chip *chip)
  41 {
  42         struct tpm_private *priv = TPM_VPRIV(chip);
  43         switch (priv->shr->state) {
  44         case VTPM_STATE_IDLE:
  45                 return VTPM_STATUS_IDLE | VTPM_STATUS_CANCELED;
  46         case VTPM_STATE_FINISH:
  47                 return VTPM_STATUS_IDLE | VTPM_STATUS_RESULT;
  48         case VTPM_STATE_SUBMIT:
  49         case VTPM_STATE_CANCEL: /* cancel requested, not yet canceled */
  50                 return VTPM_STATUS_RUNNING;
  51         default:
  52                 return 0;
  53         }
  54 }
  55
  56 static bool vtpm_req_canceled(struct tpm_chip *chip, u8 status)
  57 {
  58         return status & VTPM_STATUS_CANCELED;
  59 }
  60
  61 static void vtpm_cancel(struct tpm_chip *chip)
  62 {
  63         struct tpm_private *priv = TPM_VPRIV(chip);
  64         priv->shr->state = VTPM_STATE_CANCEL;
  65         wmb();
  66         notify_remote_via_evtchn(priv->evtchn);
  67 }
  68
  69 static unsigned int shr_data_offset(struct vtpm_shared_page *shr)
  70 {
  71         return sizeof(*shr) + sizeof(u32) * shr->nr_extra_pages;
  72 }
  73
  74 static int vtpm_send(struct tpm_chip *chip, u8 *buf, size_t count)
  75 {
  76         struct tpm_private *priv = TPM_VPRIV(chip);
  77         struct vtpm_shared_page *shr = priv->shr;
  78         unsigned int offset = shr_data_offset(shr);
  79
  80         u32 ordinal;
  81         unsigned long duration;
  82
  83         if (offset > PAGE_SIZE)
  84                 return -EINVAL;
  85
  86         if (offset + count > PAGE_SIZE)
  87                 return -EINVAL;
  88
  89         /* Wait for completion of any existing command or cancellation */
  90         if (wait_for_tpm_stat(chip, VTPM_STATUS_IDLE, chip->vendor.timeout_c,
  91                         &chip->vendor.read_queue, true) < 0) {
  92                 vtpm_cancel(chip);
  93                 return -ETIME;
  94         }
  95
  96         memcpy(offset + (u8 *)shr, buf, count);
  97         shr->length = count;
  98         barrier();
  99         shr->state = VTPM_STATE_SUBMIT;
 100         wmb();
 101         notify_remote_via_evtchn(priv->evtchn);
 102
 103         ordinal = be32_to_cpu(((struct tpm_input_header*)buf)->ordinal);
 104         duration = tpm_calc_ordinal_duration(chip, ordinal);
 105
 106         if (wait_for_tpm_stat(chip, VTPM_STATUS_IDLE, duration,
 107                         &chip->vendor.read_queue, true) < 0) {
 108                 /* got a signal or timeout, try to cancel */
 109                 vtpm_cancel(chip);
 110                 return -ETIME;
 111         }
 112
 113         return count;
 114 }
 115
 116 static int vtpm_recv(struct tpm_chip *chip, u8 *buf, size_t count)
 117 {
 118         struct tpm_private *priv = TPM_VPRIV(chip);
 119         struct vtpm_shared_page *shr = priv->shr;
 120         unsigned int offset = shr_data_offset(shr);
 121         size_t length = shr->length;
 122
 123         if (shr->state == VTPM_STATE_IDLE)
 124                 return -ECANCELED;
 125
 126         /* In theory the wait at the end of _send makes this one unnecessary */
 127         if (wait_for_tpm_stat(chip, VTPM_STATUS_RESULT, chip->vendor.timeout_c,
 128                         &chip->vendor.read_queue, true) < 0) {
 129                 vtpm_cancel(chip);
 130                 return -ETIME;
 131         }
 132
 133         if (offset > PAGE_SIZE)
 134                 return -EIO;
 135
 136         if (offset + length > PAGE_SIZE)
 137                 length = PAGE_SIZE - offset;
 138
 139         if (length > count)
 140                 length = count;
 141
 142         memcpy(buf, offset + (u8 *)shr, length);
 143
 144         return length;
 145 }
 146
 147 static const struct file_operations vtpm_ops = {
 148         .owner = THIS_MODULE,
 149         .llseek = no_llseek,
 150         .open = tpm_open,
 151         .read = tpm_read,
 152         .write = tpm_write,
 153         .release = tpm_release,
 154 };
 155
 156 static DEVICE_ATTR(pubek, S_IRUGO, tpm_show_pubek, NULL);
 157 static DEVICE_ATTR(pcrs, S_IRUGO, tpm_show_pcrs, NULL);
 158 static DEVICE_ATTR(enabled, S_IRUGO, tpm_show_enabled, NULL);
 159 static DEVICE_ATTR(active, S_IRUGO, tpm_show_active, NULL);
 160 static DEVICE_ATTR(owned, S_IRUGO, tpm_show_owned, NULL);
 161 static DEVICE_ATTR(temp_deactivated, S_IRUGO, tpm_show_temp_deactivated,
 162                 NULL);
 163 static DEVICE_ATTR(caps, S_IRUGO, tpm_show_caps, NULL);
 164 static DEVICE_ATTR(cancel, S_IWUSR | S_IWGRP, NULL, tpm_store_cancel);
 165 static DEVICE_ATTR(durations, S_IRUGO, tpm_show_durations, NULL);
 166 static DEVICE_ATTR(timeouts, S_IRUGO, tpm_show_timeouts, NULL);
 167
 168 static struct attribute *vtpm_attrs[] = {
 169         &dev_attr_pubek.attr,
 170         &dev_attr_pcrs.attr,
 171         &dev_attr_enabled.attr,
 172         &dev_attr_active.attr,
 173         &dev_attr_owned.attr,
 174         &dev_attr_temp_deactivated.attr,
 175         &dev_attr_caps.attr,
 176         &dev_attr_cancel.attr,
 177         &dev_attr_durations.attr,
 178         &dev_attr_timeouts.attr,
 179         NULL,
 180 };
 181
 182 static struct attribute_group vtpm_attr_grp = {
 183         .attrs = vtpm_attrs,
 184 };
 185
 186 static const struct tpm_vendor_specific tpm_vtpm = {
 187         .status = vtpm_status,
 188         .recv = vtpm_recv,
 189         .send = vtpm_send,
 190         .cancel = vtpm_cancel,
 191         .req_complete_mask = VTPM_STATUS_IDLE | VTPM_STATUS_RESULT,
 192         .req_complete_val  = VTPM_STATUS_IDLE | VTPM_STATUS_RESULT,
 193         .req_canceled      = vtpm_req_canceled,
 194         .attr_group = &vtpm_attr_grp,
 195         .miscdev = {
 196                 .fops = &vtpm_ops,
 197         },
 198 };
 199
 200 static irqreturn_t tpmif_interrupt(int dummy, void *dev_id)
 201 {
 202         struct tpm_private *priv = dev_id;
 203
 204         switch (priv->shr->state) {
 205         case VTPM_STATE_IDLE:
 206         case VTPM_STATE_FINISH:
 207                 wake_up_interruptible(&priv->chip->vendor.read_queue);
 208                 break;
 209         case VTPM_STATE_SUBMIT:
 210         case VTPM_STATE_CANCEL:
 211         default:
 212                 break;
 213         }
 214         return IRQ_HANDLED;
 215 }
 216
 217 static int setup_chip(struct device *dev, struct tpm_private *priv)
 218 {
 219         struct tpm_chip *chip;
 220
 221         chip = tpm_register_hardware(dev, &tpm_vtpm);
 222         if (!chip)
 223                 return -ENODEV;
 224
 225         init_waitqueue_head(&chip->vendor.read_queue);
 226
 227         priv->chip = chip;
 228         TPM_VPRIV(chip) = priv;
 229
 230         return 0;
 231 }
 232
 233 /* caller must clean up in case of errors */
 234 static int setup_ring(struct xenbus_device *dev, struct tpm_private *priv)
 235 {
 236         struct xenbus_transaction xbt;
 237         const char *message = NULL;
 238         int rv;
 239
 240         priv->shr = (void *)__get_free_page(GFP_KERNEL|__GFP_ZERO);
 241         if (!priv->shr) {
 242                 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
 243                 return -ENOMEM;
 244         }
 245
 246         rv = xenbus_grant_ring(dev, virt_to_mfn(priv->shr));
 247         if (rv < 0)
 248                 return rv;
 249
 250         priv->ring_ref = rv;
 251
 252         rv = xenbus_alloc_evtchn(dev, &priv->evtchn);
 253         if (rv)
 254                 return rv;
 255
 256         rv = bind_evtchn_to_irqhandler(priv->evtchn, tpmif_interrupt, 0,
 257                                        "tpmif", priv);
 258         if (rv <= 0) {
 259                 xenbus_dev_fatal(dev, rv, "allocating TPM irq");
 260                 return rv;
 261         }
 262         priv->chip->vendor.irq = rv;
 263
 264  again:
 265         rv = xenbus_transaction_start(&xbt);
 266         if (rv) {
 267                 xenbus_dev_fatal(dev, rv, "starting transaction");
 268                 return rv;
 269         }
 270
 271         rv = xenbus_printf(xbt, dev->nodename,
 272                         "ring-ref", "%u", priv->ring_ref);
 273         if (rv) {
 274                 message = "writing ring-ref";
 275                 goto abort_transaction;
 276         }
 277
 278         rv = xenbus_printf(xbt, dev->nodename, "event-channel", "%u",
 279                         priv->evtchn);
 280         if (rv) {
 281                 message = "writing event-channel";
 282                 goto abort_transaction;
 283         }
 284
 285         rv = xenbus_printf(xbt, dev->nodename, "feature-protocol-v2", "1");
 286         if (rv) {
 287                 message = "writing feature-protocol-v2";
 288                 goto abort_transaction;
 289         }
 290
 291         rv = xenbus_transaction_end(xbt, 0);
 292         if (rv == -EAGAIN)
 293                 goto again;
 294         if (rv) {
 295                 xenbus_dev_fatal(dev, rv, "completing transaction");
 296                 return rv;
 297         }
 298
 299         xenbus_switch_state(dev, XenbusStateInitialised);
 300
 301         return 0;
 302
 303  abort_transaction:
 304         xenbus_transaction_end(xbt, 1);
 305         if (message)
 306                 xenbus_dev_error(dev, rv, "%s", message);
 307
 308         return rv;
 309 }
 310
 311 static void ring_free(struct tpm_private *priv)
 312 {
 313         if (!priv)
 314                 return;
 315
 316         if (priv->ring_ref)
 317                 gnttab_end_foreign_access(priv->ring_ref, 0,
 318                                 (unsigned long)priv->shr);
 319         else
 320                 free_page((unsigned long)priv->shr);
 321
 322         if (priv->chip && priv->chip->vendor.irq)
 323                 unbind_from_irqhandler(priv->chip->vendor.irq, priv);
 324
 325         kfree(priv);
 326 }
 327
 328 static int tpmfront_probe(struct xenbus_device *dev,
 329                 const struct xenbus_device_id *id)
 330 {
 331         struct tpm_private *priv;
 332         int rv;
 333
 334         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 335         if (!priv) {
 336                 xenbus_dev_fatal(dev, -ENOMEM, "allocating priv structure");
 337                 return -ENOMEM;
 338         }
 339
 340         rv = setup_chip(&dev->dev, priv);
 341         if (rv) {
 342                 kfree(priv);
 343                 return rv;
 344         }
 345
 346         rv = setup_ring(dev, priv);
 347         if (rv) {
 348                 tpm_remove_hardware(&dev->dev);
 349                 ring_free(priv);
 350                 return rv;
 351         }
 352
 353         tpm_get_timeouts(priv->chip);
 354
 355         dev_set_drvdata(&dev->dev, priv->chip);
 356
 357         return rv;
 358 }
 359
 360 static int tpmfront_remove(struct xenbus_device *dev)
 361 {
 362         struct tpm_chip *chip = dev_get_drvdata(&dev->dev);
 363         struct tpm_private *priv = TPM_VPRIV(chip);
 364         tpm_remove_hardware(&dev->dev);
 365         ring_free(priv);
 366         TPM_VPRIV(chip) = NULL;
 367         return 0;
 368 }
 369
 370 static int tpmfront_resume(struct xenbus_device *dev)
 371 {
 372         /* A suspend/resume/migrate will interrupt a vTPM anyway */
 373         tpmfront_remove(dev);
 374         return tpmfront_probe(dev, NULL);
 375 }
 376
 377 static void backend_changed(struct xenbus_device *dev,
 378                 enum xenbus_state backend_state)
 379 {
 380         int val;
 381
 382         switch (backend_state) {
 383         case XenbusStateInitialised:
 384         case XenbusStateConnected:
 385                 if (dev->state == XenbusStateConnected)
 386                         break;
 387
 388                 if (xenbus_scanf(XBT_NIL, dev->otherend,
 389                                 "feature-protocol-v2", "%d", &val) < 0)
 390                         val = 0;
 391                 if (!val) {
 392                         xenbus_dev_fatal(dev, -EINVAL,
 393                                         "vTPM protocol 2 required");
 394                         return;
 395                 }
 396                 xenbus_switch_state(dev, XenbusStateConnected);
 397                 break;
 398
 399         case XenbusStateClosing:
 400         case XenbusStateClosed:
 401                 device_unregister(&dev->dev);
 402                 xenbus_frontend_closed(dev);
 403                 break;
 404         default:
 405                 break;
 406         }
 407 }
 408
 409 static const struct xenbus_device_id tpmfront_ids[] = {
 410         { "vtpm" },
 411         { "" }
 412 };
 413 MODULE_ALIAS("xen:vtpm");
 414
 415 static DEFINE_XENBUS_DRIVER(tpmfront, ,
 416                 .probe = tpmfront_probe,
 417                 .remove = tpmfront_remove,
 418                 .resume = tpmfront_resume,
 419                 .otherend_changed = backend_changed,
 420         );
 421
 422 static int __init xen_tpmfront_init(void)
 423 {
 424         if (!xen_domain())
 425                 return -ENODEV;
 426
 427         if (!xen_has_pv_devices())
 428                 return -ENODEV;
 429
 430         return xenbus_register_frontend(&tpmfront_driver);
 431 }
 432 module_init(xen_tpmfront_init);
 433
 434 static void __exit xen_tpmfront_exit(void)
 435 {
 436         xenbus_unregister_driver(&tpmfront_driver);
 437 }
 438 module_exit(xen_tpmfront_exit);
 439
 440 MODULE_AUTHOR("Daniel De Graaf <dgdegra@tycho.nsa.gov>");
 441 MODULE_DESCRIPTION("Xen vTPM Driver");
 442 MODULE_LICENSE("GPL");