1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
|
/*
* Copyright (C) 2004 IBM Corporation
* Authors:
* Leendert van Doorn <leendert@watson.ibm.com>
* Dave Safford <safford@watson.ibm.com>
* Reiner Sailer <sailer@watson.ibm.com>
* Kylene Hall <kjhall@us.ibm.com>
*
* Copyright (C) 2013 Obsidian Research Corp
* Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
*
* Device file system interface to the TPM
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation, version 2 of the
* License.
*
*/
#include <linux/miscdevice.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include "tpm.h"
struct file_priv {
struct tpm_chip *chip;
/* Data passed to and from the tpm via the read/write calls */
atomic_t data_pending;
struct mutex buffer_mutex;
struct timer_list user_read_timer; /* user needs to claim result */
struct work_struct work;
u8 data_buffer[TPM_BUFSIZE];
};
static void user_reader_timeout(unsigned long ptr)
{
struct file_priv *priv = (struct file_priv *)ptr;
schedule_work(&priv->work);
}
static void timeout_work(struct work_struct *work)
{
struct file_priv *priv = container_of(work, struct file_priv, work);
mutex_lock(&priv->buffer_mutex);
atomic_set(&priv->data_pending, 0);
memset(priv->data_buffer, 0, sizeof(priv->data_buffer));
mutex_unlock(&priv->buffer_mutex);
}
static int tpm_open(struct inode *inode, struct file *file)
{
struct miscdevice *misc = file->private_data;
struct tpm_chip *chip = container_of(misc, struct tpm_chip,
vendor.miscdev);
struct file_priv *priv;
/* It's assured that the chip will be opened just once,
* by the check of is_open variable, which is protected
* by driver_lock. */
if (test_and_set_bit(0, &chip->is_open)) {
dev_dbg(chip->dev, "Another process owns this TPM\n");
return -EBUSY;
}
priv = kzalloc(sizeof(*priv), GFP_KERNEL);
if (priv == NULL) {
clear_bit(0, &chip->is_open);
return -ENOMEM;
}
priv->chip = chip;
atomic_set(&priv->data_pending, 0);
mutex_init(&priv->buffer_mutex);
setup_timer(&priv->user_read_timer, user_reader_timeout,
(unsigned long)priv);
INIT_WORK(&priv->work, timeout_work);
file->private_data = priv;
get_device(chip->dev);
return 0;
}
static ssize_t tpm_read(struct file *file, char __user *buf,
size_t size, loff_t *off)
{
struct file_priv *priv = file->private_data;
ssize_t ret_size;
int rc;
del_singleshot_timer_sync(&priv->user_read_timer);
flush_work(&priv->work);
ret_size = atomic_read(&priv->data_pending);
if (ret_size > 0) { /* relay data */
ssize_t orig_ret_size = ret_size;
if (size < ret_size)
ret_size = size;
mutex_lock(&priv->buffer_mutex);
rc = copy_to_user(buf, priv->data_buffer, ret_size);
memset(priv->data_buffer, 0, orig_ret_size);
if (rc)
ret_size = -EFAULT;
mutex_unlock(&priv->buffer_mutex);
}
atomic_set(&priv->data_pending, 0);
return ret_size;
}
static ssize_t tpm_write(struct file *file, const char __user *buf,
size_t size, loff_t *off)
{
struct file_priv *priv = file->private_data;
size_t in_size = size;
ssize_t out_size;
/* cannot perform a write until the read has cleared
either via tpm_read or a user_read_timer timeout.
This also prevents splitted buffered writes from blocking here.
*/
if (atomic_read(&priv->data_pending) != 0)
return -EBUSY;
if (in_size > TPM_BUFSIZE)
return -E2BIG;
mutex_lock(&priv->buffer_mutex);
if (copy_from_user
(priv->data_buffer, (void __user *) buf, in_size)) {
mutex_unlock(&priv->buffer_mutex);
return -EFAULT;
}
/* atomic tpm command send and result receive */
out_size = tpm_transmit(priv->chip, priv->data_buffer,
sizeof(priv->data_buffer));
if (out_size < 0) {
mutex_unlock(&priv->buffer_mutex);
return out_size;
}
atomic_set(&priv->data_pending, out_size);
mutex_unlock(&priv->buffer_mutex);
/* Set a timeout by which the reader must come claim the result */
mod_timer(&priv->user_read_timer, jiffies + (60 * HZ));
return in_size;
}
/*
* Called on file close
*/
static int tpm_release(struct inode *inode, struct file *file)
{
struct file_priv *priv = file->private_data;
del_singleshot_timer_sync(&priv->user_read_timer);
flush_work(&priv->work);
file->private_data = NULL;
atomic_set(&priv->data_pending, 0);
clear_bit(0, &priv->chip->is_open);
put_device(priv->chip->dev);
kfree(priv);
return 0;
}
static const struct file_operations tpm_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.open = tpm_open,
.read = tpm_read,
.write = tpm_write,
.release = tpm_release,
};
int tpm_dev_add_device(struct tpm_chip *chip)
{
int rc;
chip->vendor.miscdev.fops = &tpm_fops;
if (chip->dev_num == 0)
chip->vendor.miscdev.minor = TPM_MINOR;
else
chip->vendor.miscdev.minor = MISC_DYNAMIC_MINOR;
chip->vendor.miscdev.name = chip->devname;
chip->vendor.miscdev.parent = chip->dev;
rc = misc_register(&chip->vendor.miscdev);
if (rc) {
chip->vendor.miscdev.name = NULL;
dev_err(chip->dev,
"unable to misc_register %s, minor %d err=%d\n",
chip->vendor.miscdev.name,
chip->vendor.miscdev.minor, rc);
}
return rc;
}
void tpm_dev_del_device(struct tpm_chip *chip)
{
if (chip->vendor.miscdev.name)
misc_deregister(&chip->vendor.miscdev);
}
|
