1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2004 IBM Corporation
4 * Authors:
5 * Leendert van Doorn <leendert@watson.ibm.com>
6 * Dave Safford <safford@watson.ibm.com>
7 * Reiner Sailer <sailer@watson.ibm.com>
8 * Kylene Hall <kjhall@us.ibm.com>
9 *
10 * Copyright (C) 2013 Obsidian Research Corp
11 * Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
12 *
13 * Device file system interface to the TPM
14 */
15 #include <linux/poll.h>
16 #include <linux/slab.h>
17 #include <linux/uaccess.h>
18 #include <linux/workqueue.h>
19 #include "tpm.h"
20 #include "tpm-dev.h"
21
22 static struct workqueue_struct *tpm_dev_wq;
23 static DEFINE_MUTEX(tpm_dev_wq_lock);
24
tpm_dev_transmit(struct tpm_chip * chip,struct tpm_space * space,u8 * buf,size_t bufsiz)25 static ssize_t tpm_dev_transmit(struct tpm_chip *chip, struct tpm_space *space,
26 u8 *buf, size_t bufsiz)
27 {
28 struct tpm_header *header = (void *)buf;
29 ssize_t ret, len;
30
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.
34 */
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);
41 }
42 if (ret)
43 goto out_rc;
44
45 len = tpm_transmit(chip, buf, bufsiz);
46 if (len < 0)
47 ret = len;
48
49 if (!ret)
50 ret = tpm2_commit_space(chip, space, buf, &len);
51
52 out_rc:
53 return ret ? ret : len;
54 }
55
tpm_dev_async_work(struct work_struct * work)56 static void tpm_dev_async_work(struct work_struct *work)
57 {
58 struct file_priv *priv =
59 container_of(work, struct file_priv, async_work);
60 ssize_t ret;
61
62 mutex_lock(&priv->buffer_mutex);
63 priv->command_enqueued = false;
64 ret = tpm_try_get_ops(priv->chip);
65 if (ret) {
66 priv->response_length = ret;
67 goto out;
68 }
69
70 ret = tpm_dev_transmit(priv->chip, priv->space, priv->data_buffer,
71 sizeof(priv->data_buffer));
72 tpm_put_ops(priv->chip);
73 if (ret > 0) {
74 priv->response_length = ret;
75 mod_timer(&priv->user_read_timer, jiffies + (120 * HZ));
76 }
77 out:
78 mutex_unlock(&priv->buffer_mutex);
79 wake_up_interruptible(&priv->async_wait);
80 }
81
user_reader_timeout(struct timer_list * t)82 static void user_reader_timeout(struct timer_list *t)
83 {
84 struct file_priv *priv = from_timer(priv, t, user_read_timer);
85
86 pr_warn("TPM user space timeout is deprecated (pid=%d)\n",
87 task_tgid_nr(current));
88
89 schedule_work(&priv->timeout_work);
90 }
91
tpm_timeout_work(struct work_struct * work)92 static void tpm_timeout_work(struct work_struct *work)
93 {
94 struct file_priv *priv = container_of(work, struct file_priv,
95 timeout_work);
96
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);
103 }
104
tpm_common_open(struct file * file,struct tpm_chip * chip,struct file_priv * priv,struct tpm_space * space)105 void tpm_common_open(struct file *file, struct tpm_chip *chip,
106 struct file_priv *priv, struct tpm_space *space)
107 {
108 priv->chip = chip;
109 priv->space = space;
110 priv->response_read = true;
111
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;
118 }
119
tpm_common_read(struct file * file,char __user * buf,size_t size,loff_t * off)120 ssize_t tpm_common_read(struct file *file, char __user *buf,
121 size_t size, loff_t *off)
122 {
123 struct file_priv *priv = file->private_data;
124 ssize_t ret_size = 0;
125 int rc;
126
127 mutex_lock(&priv->buffer_mutex);
128
129 if (priv->response_length) {
130 priv->response_read = true;
131
132 ret_size = min_t(ssize_t, size, priv->response_length);
133 if (ret_size <= 0) {
134 priv->response_length = 0;
135 goto out;
136 }
137
138 rc = copy_to_user(buf, priv->data_buffer + *off, ret_size);
139 if (rc) {
140 memset(priv->data_buffer, 0, TPM_BUFSIZE);
141 priv->response_length = 0;
142 ret_size = -EFAULT;
143 } else {
144 memset(priv->data_buffer + *off, 0, ret_size);
145 priv->response_length -= ret_size;
146 *off += ret_size;
147 }
148 }
149
150 out:
151 if (!priv->response_length) {
152 *off = 0;
153 del_singleshot_timer_sync(&priv->user_read_timer);
154 flush_work(&priv->timeout_work);
155 }
156 mutex_unlock(&priv->buffer_mutex);
157 return ret_size;
158 }
159
tpm_common_write(struct file * file,const char __user * buf,size_t size,loff_t * off)160 ssize_t tpm_common_write(struct file *file, const char __user *buf,
161 size_t size, loff_t *off)
162 {
163 struct file_priv *priv = file->private_data;
164 int ret = 0;
165
166 if (size > TPM_BUFSIZE)
167 return -E2BIG;
168
169 mutex_lock(&priv->buffer_mutex);
170
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.
174 */
175 if ((!priv->response_read && priv->response_length) ||
176 priv->command_enqueued) {
177 ret = -EBUSY;
178 goto out;
179 }
180
181 if (copy_from_user(priv->data_buffer, buf, size)) {
182 ret = -EFAULT;
183 goto out;
184 }
185
186 if (size < 6 ||
187 size < be32_to_cpu(*((__be32 *)(priv->data_buffer + 2)))) {
188 ret = -EINVAL;
189 goto out;
190 }
191
192 priv->response_length = 0;
193 priv->response_read = false;
194 *off = 0;
195
196 /*
197 * If in nonblocking mode schedule an async job to send
198 * the command return the size.
199 * In case of error the err code will be returned in
200 * the subsequent read call.
201 */
202 if (file->f_flags & O_NONBLOCK) {
203 priv->command_enqueued = true;
204 queue_work(tpm_dev_wq, &priv->async_work);
205 mutex_unlock(&priv->buffer_mutex);
206 return size;
207 }
208
209 /* atomic tpm command send and result receive. We only hold the ops
210 * lock during this period so that the tpm can be unregistered even if
211 * the char dev is held open.
212 */
213 if (tpm_try_get_ops(priv->chip)) {
214 ret = -EPIPE;
215 goto out;
216 }
217
218 ret = tpm_dev_transmit(priv->chip, priv->space, priv->data_buffer,
219 sizeof(priv->data_buffer));
220 tpm_put_ops(priv->chip);
221
222 if (ret > 0) {
223 priv->response_length = ret;
224 mod_timer(&priv->user_read_timer, jiffies + (120 * HZ));
225 ret = size;
226 }
227 out:
228 mutex_unlock(&priv->buffer_mutex);
229 return ret;
230 }
231
tpm_common_poll(struct file * file,poll_table * wait)232 __poll_t tpm_common_poll(struct file *file, poll_table *wait)
233 {
234 struct file_priv *priv = file->private_data;
235 __poll_t mask = 0;
236
237 poll_wait(file, &priv->async_wait, wait);
238 mutex_lock(&priv->buffer_mutex);
239
240 /*
241 * The response_length indicates if there is still response
242 * (or part of it) to be consumed. Partial reads decrease it
243 * by the number of bytes read, and write resets it the zero.
244 */
245 if (priv->response_length)
246 mask = EPOLLIN | EPOLLRDNORM;
247 else
248 mask = EPOLLOUT | EPOLLWRNORM;
249
250 mutex_unlock(&priv->buffer_mutex);
251 return mask;
252 }
253
254 /*
255 * Called on file close
256 */
tpm_common_release(struct file * file,struct file_priv * priv)257 void tpm_common_release(struct file *file, struct file_priv *priv)
258 {
259 flush_work(&priv->async_work);
260 del_singleshot_timer_sync(&priv->user_read_timer);
261 flush_work(&priv->timeout_work);
262 file->private_data = NULL;
263 priv->response_length = 0;
264 }
265
tpm_dev_common_init(void)266 int __init tpm_dev_common_init(void)
267 {
268 tpm_dev_wq = alloc_workqueue("tpm_dev_wq", WQ_MEM_RECLAIM, 0);
269
270 return !tpm_dev_wq ? -ENOMEM : 0;
271 }
272
tpm_dev_common_exit(void)273 void __exit tpm_dev_common_exit(void)
274 {
275 if (tpm_dev_wq) {
276 destroy_workqueue(tpm_dev_wq);
277 tpm_dev_wq = NULL;
278 }
279 }
280