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 void tpm_async_work(struct work_struct *work)
  31 {
  32         struct file_priv *priv =
  33                         container_of(work, struct file_priv, async_work);
  34         ssize_t ret;
  35
  36         mutex_lock(&priv->buffer_mutex);
  37         priv->command_enqueued = false;
  38         ret = tpm_transmit(priv->chip, priv->space, priv->data_buffer,
  39                            sizeof(priv->data_buffer), 0);
  40
  41         tpm_put_ops(priv->chip);
  42         if (ret > 0) {
  43                 priv->data_pending = ret;
  44                 mod_timer(&priv->user_read_timer, jiffies + (120 * HZ));
  45         }
  46         mutex_unlock(&priv->buffer_mutex);
  47         wake_up_interruptible(&priv->async_wait);
  48 }
  49
  50 static void user_reader_timeout(struct timer_list *t)
  51 {
  52         struct file_priv *priv = from_timer(priv, t, user_read_timer);
  53
  54         pr_warn("TPM user space timeout is deprecated (pid=%d)\n",
  55                 task_tgid_nr(current));
  56
  57         schedule_work(&priv->timeout_work);
  58 }
  59
  60 static void tpm_timeout_work(struct work_struct *work)
  61 {
  62         struct file_priv *priv = container_of(work, struct file_priv,
  63                                               timeout_work);
  64
  65         mutex_lock(&priv->buffer_mutex);
  66         priv->data_pending = 0;
  67         memset(priv->data_buffer, 0, sizeof(priv->data_buffer));
  68         mutex_unlock(&priv->buffer_mutex);
  69         wake_up_interruptible(&priv->async_wait);
  70 }
  71
  72 void tpm_common_open(struct file *file, struct tpm_chip *chip,
  73                      struct file_priv *priv, struct tpm_space *space)
  74 {
  75         priv->chip = chip;
  76         priv->space = space;
  77
  78         mutex_init(&priv->buffer_mutex);
  79         timer_setup(&priv->user_read_timer, user_reader_timeout, 0);
  80         INIT_WORK(&priv->timeout_work, tpm_timeout_work);
  81         INIT_WORK(&priv->async_work, tpm_async_work);
  82         init_waitqueue_head(&priv->async_wait);
  83         file->private_data = priv;
  84 }
  85
  86 ssize_t tpm_common_read(struct file *file, char __user *buf,
  87                         size_t size, loff_t *off)
  88 {
  89         struct file_priv *priv = file->private_data;
  90         ssize_t ret_size = 0;
  91         int rc;
  92
  93         del_singleshot_timer_sync(&priv->user_read_timer);
  94         flush_work(&priv->timeout_work);
  95         mutex_lock(&priv->buffer_mutex);
  96
  97         if (priv->data_pending) {
  98                 ret_size = min_t(ssize_t, size, priv->data_pending);
  99                 if (ret_size > 0) {
 100                         rc = copy_to_user(buf, priv->data_buffer, ret_size);
 101                         memset(priv->data_buffer, 0, priv->data_pending);
 102                         if (rc)
 103                                 ret_size = -EFAULT;
 104                 }
 105
 106                 priv->data_pending = 0;
 107         }
 108
 109         mutex_unlock(&priv->buffer_mutex);
 110         return ret_size;
 111 }
 112
 113 ssize_t tpm_common_write(struct file *file, const char __user *buf,
 114                          size_t size, loff_t *off)
 115 {
 116         struct file_priv *priv = file->private_data;
 117         int ret = 0;
 118
 119         if (size > TPM_BUFSIZE)
 120                 return -E2BIG;
 121
 122         mutex_lock(&priv->buffer_mutex);
 123
 124         /* Cannot perform a write until the read has cleared either via
 125          * tpm_read or a user_read_timer timeout. This also prevents split
 126          * buffered writes from blocking here.
 127          */
 128         if (priv->data_pending != 0 || priv->command_enqueued) {
 129                 ret = -EBUSY;
 130                 goto out;
 131         }
 132
 133         if (copy_from_user(priv->data_buffer, buf, size)) {
 134                 ret = -EFAULT;
 135                 goto out;
 136         }
 137
 138         if (size < 6 ||
 139             size < be32_to_cpu(*((__be32 *)(priv->data_buffer + 2)))) {
 140                 ret = -EINVAL;
 141                 goto out;
 142         }
 143
 144         /* atomic tpm command send and result receive. We only hold the ops
 145          * lock during this period so that the tpm can be unregistered even if
 146          * the char dev is held open.
 147          */
 148         if (tpm_try_get_ops(priv->chip)) {
 149                 ret = -EPIPE;
 150                 goto out;
 151         }
 152
 153         /*
 154          * If in nonblocking mode schedule an async job to send
 155          * the command return the size.
 156          * In case of error the err code will be returned in
 157          * the subsequent read call.
 158          */
 159         if (file->f_flags & O_NONBLOCK) {
 160                 priv->command_enqueued = true;
 161                 queue_work(tpm_dev_wq, &priv->async_work);
 162                 mutex_unlock(&priv->buffer_mutex);
 163                 return size;
 164         }
 165
 166         ret = tpm_transmit(priv->chip, priv->space, priv->data_buffer,
 167                            sizeof(priv->data_buffer), 0);
 168         tpm_put_ops(priv->chip);
 169
 170         if (ret > 0) {
 171                 priv->data_pending = ret;
 172                 mod_timer(&priv->user_read_timer, jiffies + (120 * HZ));
 173                 ret = size;
 174         }
 175 out:
 176         mutex_unlock(&priv->buffer_mutex);
 177         return ret;
 178 }
 179
 180 __poll_t tpm_common_poll(struct file *file, poll_table *wait)
 181 {
 182         struct file_priv *priv = file->private_data;
 183         __poll_t mask = 0;
 184
 185         poll_wait(file, &priv->async_wait, wait);
 186
 187         if (priv->data_pending)
 188                 mask = EPOLLIN | EPOLLRDNORM;
 189         else
 190                 mask = EPOLLOUT | EPOLLWRNORM;
 191
 192         return mask;
 193 }
 194
 195 /*
 196  * Called on file close
 197  */
 198 void tpm_common_release(struct file *file, struct file_priv *priv)
 199 {
 200         flush_work(&priv->async_work);
 201         del_singleshot_timer_sync(&priv->user_read_timer);
 202         flush_work(&priv->timeout_work);
 203         file->private_data = NULL;
 204         priv->data_pending = 0;
 205 }
 206
 207 int __init tpm_dev_common_init(void)
 208 {
 209         tpm_dev_wq = alloc_workqueue("tpm_dev_wq", WQ_MEM_RECLAIM, 0);
 210
 211         return !tpm_dev_wq ? -ENOMEM : 0;
 212 }
 213
 214 void __exit tpm_dev_common_exit(void)
 215 {
 216         if (tpm_dev_wq) {
 217                 destroy_workqueue(tpm_dev_wq);
 218                 tpm_dev_wq = NULL;
 219         }
 220 }