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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/slab.h>
16#include "tpm-dev.h"
17
18static int tpm_open(struct inode *inode, struct file *file)
19{
20 struct tpm_chip *chip;
21 struct file_priv *priv;
22
23 chip = container_of(inode->i_cdev, struct tpm_chip, cdev);
24
25 /* It's assured that the chip will be opened just once,
26 * by the check of is_open variable, which is protected
27 * by driver_lock. */
28 if (test_and_set_bit(0, &chip->is_open)) {
29 dev_dbg(&chip->dev, "Another process owns this TPM\n");
30 return -EBUSY;
31 }
32
33 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
34 if (priv == NULL)
35 goto out;
36
37 tpm_common_open(file, chip, priv, NULL);
38
39 return 0;
40
41 out:
42 clear_bit(0, &chip->is_open);
43 return -ENOMEM;
44}
45
46/*
47 * Called on file close
48 */
49static int tpm_release(struct inode *inode, struct file *file)
50{
51 struct file_priv *priv = file->private_data;
52
53 tpm_common_release(file, priv);
54 clear_bit(0, &priv->chip->is_open);
55 kfree(priv);
56
57 return 0;
58}
59
60const struct file_operations tpm_fops = {
61 .owner = THIS_MODULE,
62 .llseek = no_llseek,
63 .open = tpm_open,
64 .read = tpm_common_read,
65 .write = tpm_common_write,
66 .poll = tpm_common_poll,
67 .release = tpm_release,
68};
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/miscdevice.h>
21#include <linux/slab.h>
22#include <linux/uaccess.h>
23#include "tpm.h"
24
25struct file_priv {
26 struct tpm_chip *chip;
27
28 /* Data passed to and from the tpm via the read/write calls */
29 atomic_t data_pending;
30 struct mutex buffer_mutex;
31
32 struct timer_list user_read_timer; /* user needs to claim result */
33 struct work_struct work;
34
35 u8 data_buffer[TPM_BUFSIZE];
36};
37
38static void user_reader_timeout(unsigned long ptr)
39{
40 struct file_priv *priv = (struct file_priv *)ptr;
41
42 schedule_work(&priv->work);
43}
44
45static void timeout_work(struct work_struct *work)
46{
47 struct file_priv *priv = container_of(work, struct file_priv, work);
48
49 mutex_lock(&priv->buffer_mutex);
50 atomic_set(&priv->data_pending, 0);
51 memset(priv->data_buffer, 0, sizeof(priv->data_buffer));
52 mutex_unlock(&priv->buffer_mutex);
53}
54
55static int tpm_open(struct inode *inode, struct file *file)
56{
57 struct miscdevice *misc = file->private_data;
58 struct tpm_chip *chip = container_of(misc, struct tpm_chip,
59 vendor.miscdev);
60 struct file_priv *priv;
61
62 /* It's assured that the chip will be opened just once,
63 * by the check of is_open variable, which is protected
64 * by driver_lock. */
65 if (test_and_set_bit(0, &chip->is_open)) {
66 dev_dbg(chip->dev, "Another process owns this TPM\n");
67 return -EBUSY;
68 }
69
70 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
71 if (priv == NULL) {
72 clear_bit(0, &chip->is_open);
73 return -ENOMEM;
74 }
75
76 priv->chip = chip;
77 atomic_set(&priv->data_pending, 0);
78 mutex_init(&priv->buffer_mutex);
79 setup_timer(&priv->user_read_timer, user_reader_timeout,
80 (unsigned long)priv);
81 INIT_WORK(&priv->work, timeout_work);
82
83 file->private_data = priv;
84 get_device(chip->dev);
85 return 0;
86}
87
88static ssize_t tpm_read(struct file *file, char __user *buf,
89 size_t size, loff_t *off)
90{
91 struct file_priv *priv = file->private_data;
92 ssize_t ret_size;
93 int rc;
94
95 del_singleshot_timer_sync(&priv->user_read_timer);
96 flush_work(&priv->work);
97 ret_size = atomic_read(&priv->data_pending);
98 if (ret_size > 0) { /* relay data */
99 ssize_t orig_ret_size = ret_size;
100 if (size < ret_size)
101 ret_size = size;
102
103 mutex_lock(&priv->buffer_mutex);
104 rc = copy_to_user(buf, priv->data_buffer, ret_size);
105 memset(priv->data_buffer, 0, orig_ret_size);
106 if (rc)
107 ret_size = -EFAULT;
108
109 mutex_unlock(&priv->buffer_mutex);
110 }
111
112 atomic_set(&priv->data_pending, 0);
113
114 return ret_size;
115}
116
117static ssize_t tpm_write(struct file *file, const char __user *buf,
118 size_t size, loff_t *off)
119{
120 struct file_priv *priv = file->private_data;
121 size_t in_size = size;
122 ssize_t out_size;
123
124 /* cannot perform a write until the read has cleared
125 either via tpm_read or a user_read_timer timeout.
126 This also prevents splitted buffered writes from blocking here.
127 */
128 if (atomic_read(&priv->data_pending) != 0)
129 return -EBUSY;
130
131 if (in_size > TPM_BUFSIZE)
132 return -E2BIG;
133
134 mutex_lock(&priv->buffer_mutex);
135
136 if (copy_from_user
137 (priv->data_buffer, (void __user *) buf, in_size)) {
138 mutex_unlock(&priv->buffer_mutex);
139 return -EFAULT;
140 }
141
142 /* atomic tpm command send and result receive */
143 out_size = tpm_transmit(priv->chip, priv->data_buffer,
144 sizeof(priv->data_buffer));
145 if (out_size < 0) {
146 mutex_unlock(&priv->buffer_mutex);
147 return out_size;
148 }
149
150 atomic_set(&priv->data_pending, out_size);
151 mutex_unlock(&priv->buffer_mutex);
152
153 /* Set a timeout by which the reader must come claim the result */
154 mod_timer(&priv->user_read_timer, jiffies + (60 * HZ));
155
156 return in_size;
157}
158
159/*
160 * Called on file close
161 */
162static int tpm_release(struct inode *inode, struct file *file)
163{
164 struct file_priv *priv = file->private_data;
165
166 del_singleshot_timer_sync(&priv->user_read_timer);
167 flush_work(&priv->work);
168 file->private_data = NULL;
169 atomic_set(&priv->data_pending, 0);
170 clear_bit(0, &priv->chip->is_open);
171 put_device(priv->chip->dev);
172 kfree(priv);
173 return 0;
174}
175
176static const struct file_operations tpm_fops = {
177 .owner = THIS_MODULE,
178 .llseek = no_llseek,
179 .open = tpm_open,
180 .read = tpm_read,
181 .write = tpm_write,
182 .release = tpm_release,
183};
184
185int tpm_dev_add_device(struct tpm_chip *chip)
186{
187 int rc;
188
189 chip->vendor.miscdev.fops = &tpm_fops;
190 if (chip->dev_num == 0)
191 chip->vendor.miscdev.minor = TPM_MINOR;
192 else
193 chip->vendor.miscdev.minor = MISC_DYNAMIC_MINOR;
194
195 chip->vendor.miscdev.name = chip->devname;
196 chip->vendor.miscdev.parent = chip->dev;
197
198 rc = misc_register(&chip->vendor.miscdev);
199 if (rc) {
200 chip->vendor.miscdev.name = NULL;
201 dev_err(chip->dev,
202 "unable to misc_register %s, minor %d err=%d\n",
203 chip->vendor.miscdev.name,
204 chip->vendor.miscdev.minor, rc);
205 }
206 return rc;
207}
208
209void tpm_dev_del_device(struct tpm_chip *chip)
210{
211 if (chip->vendor.miscdev.name)
212 misc_deregister(&chip->vendor.miscdev);
213}