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