drivers/char/tpm/tpm-dev-common.c

   1 /*
   2  * Copyright (C) 2004 IBM Corporation
   3  * Authors:
   4  * Leendert van Doorn <leendert@watson.ibm.com>
   5  * Dave Safford <safford@watson.ibm.com>
   6  * Reiner Sailer <sailer@watson.ibm.com>
   7  * Kylene Hall <kjhall@us.ibm.com>
   8  *
   9  * Copyright (C) 2013 Obsidian Research Corp
  10  * Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
  11  *
  12  * Device file system interface to the TPM
  13  *
  14  * This program is free software; you can redistribute it and/or
  15  * modify it under the terms of the GNU General Public License as
  16  * published by the Free Software Foundation, version 2 of the
  17  * License.
  18  *
  19  */
  20 #include <linux/poll.h>
  21 #include <linux/slab.h>
  22 #include <linux/uaccess.h>
  23 #include <linux/workqueue.h>
  24 #include "tpm.h"
  25 #include "tpm-dev.h"
  26
  27 static struct workqueue_struct *tpm_dev_wq;
  28 static DEFINE_MUTEX(tpm_dev_wq_lock);
  29
  30 static ssize_t tpm_dev_transmit(struct tpm_chip *chip, struct tpm_space *space,
  31                                 u8 *buf, size_t bufsiz)
  32 {
  33         struct tpm_header *header = (void *)buf;
  34         ssize_t ret, len;
  35
  36         ret = tpm2_prepare_space(chip, space, buf, bufsiz);
  37         /* If the command is not implemented by the TPM, synthesize a
  38          * response with a TPM2_RC_COMMAND_CODE return for user-space.
  39          */
  40         if (ret == -EOPNOTSUPP) {
  41                 header->length = cpu_to_be32(sizeof(*header));
  42                 header->tag = cpu_to_be16(TPM2_ST_NO_SESSIONS);
  43                 header->return_code = cpu_to_be32(TPM2_RC_COMMAND_CODE |
  44                                                   TSS2_RESMGR_TPM_RC_LAYER);
  45                 ret = sizeof(*header);
  46         }
  47         if (ret)
  48                 goto out_rc;
  49
  50         len = tpm_transmit(chip, buf, bufsiz);
  51         if (len < 0)
  52                 ret = len;
  53
  54         if (!ret)
  55                 ret = tpm2_commit_space(chip, space, buf, &len);
  56
  57 out_rc:
  58         return ret ? ret : len;
  59 }
  60
  61 static void tpm_dev_async_work(struct work_struct *work)
  62 {
  63         struct file_priv *priv =
  64                         container_of(work, struct file_priv, async_work);
  65         ssize_t ret;
  66
  67         mutex_lock(&priv->buffer_mutex);
  68         priv->command_enqueued = false;
  69         ret = tpm_dev_transmit(priv->chip, priv->space, priv->data_buffer,
  70                                sizeof(priv->data_buffer));
  71         tpm_put_ops(priv->chip);
  72         if (ret > 0) {
  73                 priv->response_length = ret;
  74                 mod_timer(&priv->user_read_timer, jiffies + (120 * HZ));
  75         }
  76         mutex_unlock(&priv->buffer_mutex);
  77         wake_up_interruptible(&priv->async_wait);
  78 }
  79
  80 static void user_reader_timeout(struct timer_list *t)
  81 {
  82         struct file_priv *priv = from_timer(priv, t, user_read_timer);
  83
  84         pr_warn("TPM user space timeout is deprecated (pid=%d)\n",
  85                 task_tgid_nr(current));
  86
  87         schedule_work(&priv->timeout_work);
  88 }
  89
  90 static void tpm_timeout_work(struct work_struct *work)
  91 {
  92         struct file_priv *priv = container_of(work, struct file_priv,
  93                                               timeout_work);
  94
  95         mutex_lock(&priv->buffer_mutex);
  96         priv->response_read = true;
  97         priv->response_length = 0;
  98         memset(priv->data_buffer, 0, sizeof(priv->data_buffer));
  99         mutex_unlock(&priv->buffer_mutex);
 100         wake_up_interruptible(&priv->async_wait);
 101 }
 102
 103 void tpm_common_open(struct file *file, struct tpm_chip *chip,
 104                      struct file_priv *priv, struct tpm_space *space)
 105 {
 106         priv->chip = chip;
 107         priv->space = space;
 108         priv->response_read = true;
 109
 110         mutex_init(&priv->buffer_mutex);
 111         timer_setup(&priv->user_read_timer, user_reader_timeout, 0);
 112         INIT_WORK(&priv->timeout_work, tpm_timeout_work);
 113         INIT_WORK(&priv->async_work, tpm_dev_async_work);
 114         init_waitqueue_head(&priv->async_wait);
 115         file->private_data = priv;
 116 }
 117
 118 ssize_t tpm_common_read(struct file *file, char __user *buf,
 119                         size_t size, loff_t *off)
 120 {
 121         struct file_priv *priv = file->private_data;
 122         ssize_t ret_size = 0;
 123         int rc;
 124
 125         mutex_lock(&priv->buffer_mutex);
 126
 127         if (priv->response_length) {
 128                 priv->response_read = true;
 129
 130                 ret_size = min_t(ssize_t, size, priv->response_length);
 131                 if (!ret_size) {
 132                         priv->response_length = 0;
 133                         goto out;
 134                 }
 135
 136                 rc = copy_to_user(buf, priv->data_buffer + *off, ret_size);
 137                 if (rc) {
 138                         memset(priv->data_buffer, 0, TPM_BUFSIZE);
 139                         priv->response_length = 0;
 140                         ret_size = -EFAULT;
 141                 } else {
 142                         memset(priv->data_buffer + *off, 0, ret_size);
 143                         priv->response_length -= ret_size;
 144                         *off += ret_size;
 145                 }
 146         }
 147
 148 out:
 149         if (!priv->response_length) {
 150                 *off = 0;
 151                 del_singleshot_timer_sync(&priv->user_read_timer);
 152                 flush_work(&priv->timeout_work);
 153         }
 154         mutex_unlock(&priv->buffer_mutex);
 155         return ret_size;
 156 }
 157
 158 ssize_t tpm_common_write(struct file *file, const char __user *buf,
 159                          size_t size, loff_t *off)
 160 {
 161         struct file_priv *priv = file->private_data;
 162         int ret = 0;
 163
 164         if (size > TPM_BUFSIZE)
 165                 return -E2BIG;
 166
 167         mutex_lock(&priv->buffer_mutex);
 168
 169         /* Cannot perform a write until the read has cleared either via
 170          * tpm_read or a user_read_timer timeout. This also prevents split
 171          * buffered writes from blocking here.
 172          */
 173         if ((!priv->response_read && priv->response_length) ||
 174             priv->command_enqueued) {
 175                 ret = -EBUSY;
 176                 goto out;
 177         }
 178
 179         if (copy_from_user(priv->data_buffer, buf, size)) {
 180                 ret = -EFAULT;
 181                 goto out;
 182         }
 183
 184         if (size < 6 ||
 185             size < be32_to_cpu(*((__be32 *)(priv->data_buffer + 2)))) {
 186                 ret = -EINVAL;
 187                 goto out;
 188         }
 189
 190         /* atomic tpm command send and result receive. We only hold the ops
 191          * lock during this period so that the tpm can be unregistered even if
 192          * the char dev is held open.
 193          */
 194         if (tpm_try_get_ops(priv->chip)) {
 195                 ret = -EPIPE;
 196                 goto out;
 197         }
 198
 199         priv->response_length = 0;
 200         priv->response_read = false;
 201         *off = 0;
 202
 203         /*
 204          * If in nonblocking mode schedule an async job to send
 205          * the command return the size.
 206          * In case of error the err code will be returned in
 207          * the subsequent read call.
 208          */
 209         if (file->f_flags & O_NONBLOCK) {
 210                 priv->command_enqueued = true;
 211                 queue_work(tpm_dev_wq, &priv->async_work);
 212                 mutex_unlock(&priv->buffer_mutex);
 213                 return size;
 214         }
 215
 216         ret = tpm_dev_transmit(priv->chip, priv->space, priv->data_buffer,
 217                                sizeof(priv->data_buffer));
 218         tpm_put_ops(priv->chip);
 219
 220         if (ret > 0) {
 221                 priv->response_length = ret;
 222                 mod_timer(&priv->user_read_timer, jiffies + (120 * HZ));
 223                 ret = size;
 224         }
 225 out:
 226         mutex_unlock(&priv->buffer_mutex);
 227         return ret;
 228 }
 229
 230 __poll_t tpm_common_poll(struct file *file, poll_table *wait)
 231 {
 232         struct file_priv *priv = file->private_data;
 233         __poll_t mask = 0;
 234
 235         poll_wait(file, &priv->async_wait, wait);
 236         mutex_lock(&priv->buffer_mutex);
 237
 238         /*
 239          * The response_length indicates if there is still response
 240          * (or part of it) to be consumed. Partial reads decrease it
 241          * by the number of bytes read, and write resets it the zero.
 242          */
 243         if (priv->response_length)
 244                 mask = EPOLLIN | EPOLLRDNORM;
 245         else
 246                 mask = EPOLLOUT | EPOLLWRNORM;
 247
 248         mutex_unlock(&priv->buffer_mutex);
 249         return mask;
 250 }
 251
 252 /*
 253  * Called on file close
 254  */
 255 void tpm_common_release(struct file *file, struct file_priv *priv)
 256 {
 257         flush_work(&priv->async_work);
 258         del_singleshot_timer_sync(&priv->user_read_timer);
 259         flush_work(&priv->timeout_work);
 260         file->private_data = NULL;
 261         priv->response_length = 0;
 262 }
 263
 264 int __init tpm_dev_common_init(void)
 265 {
 266         tpm_dev_wq = alloc_workqueue("tpm_dev_wq", WQ_MEM_RECLAIM, 0);
 267
 268         return !tpm_dev_wq ? -ENOMEM : 0;
 269 }
 270
 271 void __exit tpm_dev_common_exit(void)
 272 {
 273         if (tpm_dev_wq) {
 274                 destroy_workqueue(tpm_dev_wq);
 275                 tpm_dev_wq = NULL;
 276         }
 277 }