tpm20.c

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    1 /*-
    2  * Copyright (c) 2018 Stormshield.
    3  * Copyright (c) 2018 Semihalf.
    4  * All rights reserved.
    5  *
    6  * Redistribution and use in source and binary forms, with or without
    7  * modification, are permitted provided that the following conditions
    8  * are met:
    9  * 1. Redistributions of source code must retain the above copyright
   10  *    notice, this list of conditions and the following disclaimer.
   11  * 2. Redistributions in binary form must reproduce the above copyright
   12  *    notice, this list of conditions and the following disclaimer in the
   13  *    documentation and/or other materials provided with the distribution.
   14  *
   15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
   17  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   18  * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
   19  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
   20  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
   21  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
   23  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
   24  * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   25  * POSSIBILITY OF SUCH DAMAGE.
   26  */
   27 
   28 #include <sys/cdefs.h>
   29 __FBSDID("$FreeBSD$");
   30 
   31 #include <sys/random.h>
   32 
   33 #include "tpm20.h"
   34 
   35 #define TPM_HARVEST_SIZE     16
   36 /*
   37  * Perform a harvest every 10 seconds.
   38  * Since discrete TPMs are painfully slow
   39  * we don't want to execute this too often
   40  * as the chip is likely to be used by others too.
   41  */
   42 #define TPM_HARVEST_INTERVAL 10
   43 
   44 MALLOC_DEFINE(M_TPM20, "tpm_buffer", "buffer for tpm 2.0 driver");
   45 
   46 static void tpm20_discard_buffer(void *arg);
   47 #ifdef TPM_HARVEST
   48 static void tpm20_harvest(void *arg, int unused);
   49 #endif
   50 static int  tpm20_save_state(device_t dev, bool suspend);
   51 
   52 static d_open_t         tpm20_open;
   53 static d_close_t        tpm20_close;
   54 static d_read_t         tpm20_read;
   55 static d_write_t        tpm20_write;
   56 static d_ioctl_t        tpm20_ioctl;
   57 
   58 static struct cdevsw tpm20_cdevsw = {
   59         .d_version = D_VERSION,
   60         .d_open = tpm20_open,
   61         .d_close = tpm20_close,
   62         .d_read = tpm20_read,
   63         .d_write = tpm20_write,
   64         .d_ioctl = tpm20_ioctl,
   65         .d_name = "tpm20",
   66 };
   67 
   68 int
   69 tpm20_read(struct cdev *dev, struct uio *uio, int flags)
   70 {
   71         struct tpm_sc *sc;
   72         size_t bytes_to_transfer;
   73         int result = 0;
   74 
   75         sc = (struct tpm_sc *)dev->si_drv1;
   76 
   77         callout_stop(&sc->discard_buffer_callout);
   78         sx_xlock(&sc->dev_lock);
   79         if (sc->owner_tid != uio->uio_td->td_tid) {
   80                 sx_xunlock(&sc->dev_lock);
   81                 return (EPERM);
   82         }
   83 
   84         bytes_to_transfer = MIN(sc->pending_data_length, uio->uio_resid);
   85         if (bytes_to_transfer > 0) {
   86                 result = uiomove((caddr_t) sc->buf, bytes_to_transfer, uio);
   87                 memset(sc->buf, 0, TPM_BUFSIZE);
   88                 sc->pending_data_length = 0;
   89                 cv_signal(&sc->buf_cv);
   90         } else {
   91                 result = ETIMEDOUT;
   92         }
   93 
   94         sx_xunlock(&sc->dev_lock);
   95 
   96         return (result);
   97 }
   98 
   99 int
  100 tpm20_write(struct cdev *dev, struct uio *uio, int flags)
  101 {
  102         struct tpm_sc *sc;
  103         size_t byte_count;
  104         int result = 0;
  105 
  106         sc = (struct tpm_sc *)dev->si_drv1;
  107 
  108         byte_count = uio->uio_resid;
  109         if (byte_count < TPM_HEADER_SIZE) {
  110                 device_printf(sc->dev,
  111                     "Requested transfer is too small\n");
  112                 return (EINVAL);
  113         }
  114 
  115         if (byte_count > TPM_BUFSIZE) {
  116                 device_printf(sc->dev,
  117                     "Requested transfer is too large\n");
  118                 return (E2BIG);
  119         }
  120 
  121         sx_xlock(&sc->dev_lock);
  122 
  123         while (sc->pending_data_length != 0)
  124                 cv_wait(&sc->buf_cv, &sc->dev_lock);
  125 
  126         result = uiomove(sc->buf, byte_count, uio);
  127         if (result != 0) {
  128                 sx_xunlock(&sc->dev_lock);
  129                 return (result);
  130         }
  131 
  132         result = sc->transmit(sc, byte_count);
  133 
  134         if (result == 0) {
  135                 callout_reset(&sc->discard_buffer_callout,
  136                     TPM_READ_TIMEOUT / tick, tpm20_discard_buffer, sc);
  137                 sc->owner_tid = uio->uio_td->td_tid;
  138         }
  139 
  140         sx_xunlock(&sc->dev_lock);
  141         return (result);
  142 }
  143 
  144 static void
  145 tpm20_discard_buffer(void *arg)
  146 {
  147         struct tpm_sc *sc;
  148 
  149         sc = (struct tpm_sc *)arg;
  150         if (callout_pending(&sc->discard_buffer_callout))
  151                 return;
  152 
  153         sx_xlock(&sc->dev_lock);
  154 
  155         memset(sc->buf, 0, TPM_BUFSIZE);
  156         sc->pending_data_length = 0;
  157 
  158         cv_signal(&sc->buf_cv);
  159         sx_xunlock(&sc->dev_lock);
  160 
  161         device_printf(sc->dev,
  162             "User failed to read buffer in time\n");
  163 }
  164 
  165 int
  166 tpm20_open(struct cdev *dev, int flag, int mode, struct thread *td)
  167 {
  168 
  169         return (0);
  170 }
  171 
  172 int
  173 tpm20_close(struct cdev *dev, int flag, int mode, struct thread *td)
  174 {
  175 
  176         return (0);
  177 }
  178 
  179 int
  180 tpm20_ioctl(struct cdev *dev, u_long cmd, caddr_t data,
  181     int flags, struct thread *td)
  182 {
  183 
  184         return (ENOTTY);
  185 }
  186 
  187 int
  188 tpm20_init(struct tpm_sc *sc)
  189 {
  190         struct make_dev_args args;
  191         int result;
  192 
  193         cv_init(&sc->buf_cv, "TPM buffer cv");
  194         callout_init(&sc->discard_buffer_callout, 1);
  195         sc->pending_data_length = 0;
  196 
  197         make_dev_args_init(&args);
  198         args.mda_devsw = &tpm20_cdevsw;
  199         args.mda_uid = UID_ROOT;
  200         args.mda_gid = GID_WHEEL;
  201         args.mda_mode = TPM_CDEV_PERM_FLAG;
  202         args.mda_si_drv1 = sc;
  203         result = make_dev_s(&args, &sc->sc_cdev, TPM_CDEV_NAME);
  204         if (result != 0)
  205                 tpm20_release(sc);
  206 
  207 #ifdef TPM_HARVEST
  208         TIMEOUT_TASK_INIT(taskqueue_thread, &sc->harvest_task, 0,
  209             tpm20_harvest, sc);
  210         taskqueue_enqueue_timeout(taskqueue_thread, &sc->harvest_task, 0);
  211 #endif
  212 
  213         return (result);
  214 
  215 }
  216 
  217 void
  218 tpm20_release(struct tpm_sc *sc)
  219 {
  220 
  221 #ifdef TPM_HARVEST
  222         if (device_is_attached(sc->dev))
  223                 taskqueue_drain_timeout(taskqueue_thread, &sc->harvest_task);
  224 #endif
  225 
  226         if (sc->buf != NULL)
  227                 free(sc->buf, M_TPM20);
  228 
  229         sx_destroy(&sc->dev_lock);
  230         cv_destroy(&sc->buf_cv);
  231         if (sc->sc_cdev != NULL)
  232                 destroy_dev(sc->sc_cdev);
  233 }
  234 
  235 int
  236 tpm20_suspend(device_t dev)
  237 {
  238         return (tpm20_save_state(dev, true));
  239 }
  240 
  241 int
  242 tpm20_shutdown(device_t dev)
  243 {
  244         return (tpm20_save_state(dev, false));
  245 }
  246 
  247 #ifdef TPM_HARVEST
  248 /*
  249  * Get TPM_HARVEST_SIZE random bytes and add them
  250  * into system entropy pool.
  251  */
  252 static void
  253 tpm20_harvest(void *arg, int unused)
  254 {
  255         struct tpm_sc *sc;
  256         unsigned char entropy[TPM_HARVEST_SIZE];
  257         uint16_t entropy_size;
  258         int result;
  259         uint8_t cmd[] = {
  260                 0x80, 0x01,             /* TPM_ST_NO_SESSIONS tag*/
  261                 0x00, 0x00, 0x00, 0x0c, /* cmd length */
  262                 0x00, 0x00, 0x01, 0x7b, /* cmd TPM_CC_GetRandom */
  263                 0x00, TPM_HARVEST_SIZE  /* number of bytes requested */
  264         };
  265 
  266         sc = arg;
  267         sx_xlock(&sc->dev_lock);
  268         while (sc->pending_data_length != 0)
  269                 cv_wait(&sc->buf_cv, &sc->dev_lock);
  270 
  271         memcpy(sc->buf, cmd, sizeof(cmd));
  272         result = sc->transmit(sc, sizeof(cmd));
  273         if (result != 0) {
  274                 sx_xunlock(&sc->dev_lock);
  275                 return;
  276         }
  277 
  278         /* Ignore response size */
  279         sc->pending_data_length = 0;
  280 
  281         /* The number of random bytes we got is placed right after the header */
  282         entropy_size = (uint16_t) sc->buf[TPM_HEADER_SIZE + 1];
  283         if (entropy_size > 0) {
  284                 entropy_size = MIN(entropy_size, TPM_HARVEST_SIZE);
  285                 memcpy(entropy,
  286                         sc->buf + TPM_HEADER_SIZE + sizeof(uint16_t),
  287                         entropy_size);
  288         }
  289 
  290         sx_xunlock(&sc->dev_lock);
  291         if (entropy_size > 0)
  292                 random_harvest_queue(entropy, entropy_size, RANDOM_PURE_TPM);
  293 
  294         taskqueue_enqueue_timeout(taskqueue_thread, &sc->harvest_task,
  295             hz * TPM_HARVEST_INTERVAL);
  296 }
  297 #endif  /* TPM_HARVEST */
  298 
  299 static int
  300 tpm20_save_state(device_t dev, bool suspend)
  301 {
  302         struct tpm_sc *sc;
  303         uint8_t save_cmd[] = {
  304                 0x80, 0x01,             /* TPM_ST_NO_SESSIONS tag*/
  305                 0x00, 0x00, 0x00, 0x0C, /* cmd length */
  306                 0x00, 0x00, 0x01, 0x45, /* cmd TPM_CC_Shutdown */
  307                 0x00, 0x00              /* TPM_SU_STATE */
  308         };
  309 
  310         sc = device_get_softc(dev);
  311 
  312         /*
  313          * Inform the TPM whether we are going to suspend or reboot/shutdown.
  314          */
  315         if (suspend)
  316                 save_cmd[11] = 1; /* TPM_SU_STATE */
  317 
  318         if (sc == NULL || sc->buf == NULL)
  319                 return (0);
  320 
  321         sx_xlock(&sc->dev_lock);
  322 
  323         memcpy(sc->buf, save_cmd, sizeof(save_cmd));
  324         sc->transmit(sc, sizeof(save_cmd));
  325 
  326         sx_xunlock(&sc->dev_lock);
  327 
  328         return (0);
  329 }
  330 
  331 int32_t
  332 tpm20_get_timeout(uint32_t command)
  333 {
  334         int32_t timeout;
  335 
  336         switch (command) {
  337                 case TPM_CC_CreatePrimary:
  338                 case TPM_CC_Create:
  339                 case TPM_CC_CreateLoaded:
  340                         timeout = TPM_TIMEOUT_LONG;
  341                         break;
  342                 case TPM_CC_SequenceComplete:
  343                 case TPM_CC_Startup:
  344                 case TPM_CC_SequenceUpdate:
  345                 case TPM_CC_GetCapability:
  346                 case TPM_CC_PCR_Extend:
  347                 case TPM_CC_EventSequenceComplete:
  348                 case TPM_CC_HashSequenceStart:
  349                         timeout = TPM_TIMEOUT_C;
  350                         break;
  351                 default:
  352                         timeout = TPM_TIMEOUT_B;
  353                         break;
  354         }
  355         return timeout;
  356 }
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FreeBSD/Linux Kernel Cross Reference sys/dev/tpm/tpm20.c

FreeBSD/Linux Kernel Cross Reference
sys/dev/tpm/tpm20.c
