1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (C) 2004 IBM Corporation
10 * Copyright (C) 2013 Obsidian Research Corp
13 * Device file system interface to the TPM
15 #include <linux/poll.h>
16 #include <linux/slab.h>
17 #include <linux/uaccess.h>
18 #include <linux/workqueue.h>
22 static struct workqueue_struct *tpm_dev_wq;
23 static DEFINE_MUTEX(tpm_dev_wq_lock);
25 static ssize_t tpm_dev_transmit(struct tpm_chip *chip, struct tpm_space *space,
26 u8 *buf, size_t bufsiz)
28 struct tpm_header *header = (void *)buf;
31 ret = tpm2_prepare_space(chip, space, buf, bufsiz);
32 /* If the command is not implemented by the TPM, synthesize a
33 * response with a TPM2_RC_COMMAND_CODE return for user-space.
35 if (ret == -EOPNOTSUPP) {
36 header->length = cpu_to_be32(sizeof(*header));
37 header->tag = cpu_to_be16(TPM2_ST_NO_SESSIONS);
38 header->return_code = cpu_to_be32(TPM2_RC_COMMAND_CODE |
39 TSS2_RESMGR_TPM_RC_LAYER);
40 ret = sizeof(*header);
45 len = tpm_transmit(chip, buf, bufsiz);
50 ret = tpm2_commit_space(chip, space, buf, &len);
53 return ret ? ret : len;
56 static void tpm_dev_async_work(struct work_struct *work)
58 struct file_priv *priv =
59 container_of(work, struct file_priv, async_work);
62 mutex_lock(&priv->buffer_mutex);
63 priv->command_enqueued = false;
64 ret = tpm_try_get_ops(priv->chip);
66 priv->response_length = ret;
70 ret = tpm_dev_transmit(priv->chip, priv->space, priv->data_buffer,
71 sizeof(priv->data_buffer));
72 tpm_put_ops(priv->chip);
74 priv->response_length = ret;
75 mod_timer(&priv->user_read_timer, jiffies + (120 * HZ));
78 mutex_unlock(&priv->buffer_mutex);
79 wake_up_interruptible(&priv->async_wait);
82 static void user_reader_timeout(struct timer_list *t)
84 struct file_priv *priv = from_timer(priv, t, user_read_timer);
86 pr_warn("TPM user space timeout is deprecated (pid=%d)\n",
87 task_tgid_nr(current));
89 schedule_work(&priv->timeout_work);
92 static void tpm_timeout_work(struct work_struct *work)
94 struct file_priv *priv = container_of(work, struct file_priv,
97 mutex_lock(&priv->buffer_mutex);
98 priv->response_read = true;
99 priv->response_length = 0;
100 memset(priv->data_buffer, 0, sizeof(priv->data_buffer));
101 mutex_unlock(&priv->buffer_mutex);
102 wake_up_interruptible(&priv->async_wait);
105 void tpm_common_open(struct file *file, struct tpm_chip *chip,
106 struct file_priv *priv, struct tpm_space *space)
110 priv->response_read = true;
112 mutex_init(&priv->buffer_mutex);
113 timer_setup(&priv->user_read_timer, user_reader_timeout, 0);
114 INIT_WORK(&priv->timeout_work, tpm_timeout_work);
115 INIT_WORK(&priv->async_work, tpm_dev_async_work);
116 init_waitqueue_head(&priv->async_wait);
117 file->private_data = priv;
120 ssize_t tpm_common_read(struct file *file, char __user *buf,
121 size_t size, loff_t *off)
123 struct file_priv *priv = file->private_data;
124 ssize_t ret_size = 0;
127 mutex_lock(&priv->buffer_mutex);
129 if (priv->response_length) {
130 priv->response_read = true;
132 ret_size = min_t(ssize_t, size, priv->response_length);
134 priv->response_length = 0;
138 rc = copy_to_user(buf, priv->data_buffer + *off, ret_size);
140 memset(priv->data_buffer, 0, TPM_BUFSIZE);
141 priv->response_length = 0;
144 memset(priv->data_buffer + *off, 0, ret_size);
145 priv->response_length -= ret_size;
151 if (!priv->response_length) {
153 del_singleshot_timer_sync(&priv->user_read_timer);
154 flush_work(&priv->timeout_work);
156 mutex_unlock(&priv->buffer_mutex);
160 ssize_t tpm_common_write(struct file *file, const char __user *buf,
161 size_t size, loff_t *off)
163 struct file_priv *priv = file->private_data;
166 if (size > TPM_BUFSIZE)
169 mutex_lock(&priv->buffer_mutex);
171 /* Cannot perform a write until the read has cleared either via
172 * tpm_read or a user_read_timer timeout. This also prevents split
173 * buffered writes from blocking here.
175 if ((!priv->response_read && priv->response_length) ||
176 priv->command_enqueued) {
181 if (copy_from_user(priv->data_buffer, buf, size)) {
187 size < be32_to_cpu(*((__be32 *)(priv->data_buffer + 2)))) {
192 /* atomic tpm command send and result receive. We only hold the ops
193 * lock during this period so that the tpm can be unregistered even if
194 * the char dev is held open.
196 if (tpm_try_get_ops(priv->chip)) {
201 priv->response_length = 0;
202 priv->response_read = false;
206 * If in nonblocking mode schedule an async job to send
207 * the command return the size.
208 * In case of error the err code will be returned in
209 * the subsequent read call.
211 if (file->f_flags & O_NONBLOCK) {
212 priv->command_enqueued = true;
213 queue_work(tpm_dev_wq, &priv->async_work);
214 tpm_put_ops(priv->chip);
215 mutex_unlock(&priv->buffer_mutex);
219 ret = tpm_dev_transmit(priv->chip, priv->space, priv->data_buffer,
220 sizeof(priv->data_buffer));
221 tpm_put_ops(priv->chip);
224 priv->response_length = ret;
225 mod_timer(&priv->user_read_timer, jiffies + (120 * HZ));
229 mutex_unlock(&priv->buffer_mutex);
233 __poll_t tpm_common_poll(struct file *file, poll_table *wait)
235 struct file_priv *priv = file->private_data;
238 poll_wait(file, &priv->async_wait, wait);
239 mutex_lock(&priv->buffer_mutex);
242 * The response_length indicates if there is still response
243 * (or part of it) to be consumed. Partial reads decrease it
244 * by the number of bytes read, and write resets it the zero.
246 if (priv->response_length)
247 mask = EPOLLIN | EPOLLRDNORM;
249 mask = EPOLLOUT | EPOLLWRNORM;
251 mutex_unlock(&priv->buffer_mutex);
256 * Called on file close
258 void tpm_common_release(struct file *file, struct file_priv *priv)
260 flush_work(&priv->async_work);
261 del_singleshot_timer_sync(&priv->user_read_timer);
262 flush_work(&priv->timeout_work);
263 file->private_data = NULL;
264 priv->response_length = 0;
267 int __init tpm_dev_common_init(void)
269 tpm_dev_wq = alloc_workqueue("tpm_dev_wq", WQ_MEM_RECLAIM, 0);
271 return !tpm_dev_wq ? -ENOMEM : 0;
274 void __exit tpm_dev_common_exit(void)
277 destroy_workqueue(tpm_dev_wq);