aboutsummaryrefslogtreecommitdiff
path: root/drivers/char/tpm/tpm-dev-common.c
blob: 610638a80383d4a104a6fe1ec42479722f222f49 (plain)
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
/*
 * 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/slab.h>
#include <linux/uaccess.h>
#include "tpm.h"
#include "tpm-dev.h"

static void user_reader_timeout(unsigned long ptr)
{
	struct file_priv *priv = (struct file_priv *)ptr;

	pr_warn("TPM user space timeout is deprecated (pid=%d)\n",
		task_tgid_nr(current));

	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);
}

void tpm_common_open(struct file *file, struct tpm_chip *chip,
		     struct file_priv *priv)
{
	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;
}

ssize_t tpm_common_read(struct file *file, char __user *buf,
			size_t size, loff_t *off)
{
	struct file_priv *priv = file->private_data;
	ssize_t ret_size;
	ssize_t orig_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 */
		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;
}

ssize_t tpm_common_write(struct file *file, const char __user *buf,
			 size_t size, loff_t *off, struct tpm_space *space)
{
	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 split
	 * 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. We only hold the ops
	 * lock during this period so that the tpm can be unregistered even if
	 * the char dev is held open.
	 */
	if (tpm_try_get_ops(priv->chip)) {
		mutex_unlock(&priv->buffer_mutex);
		return -EPIPE;
	}
	out_size = tpm_transmit(priv->chip, space, priv->data_buffer,
				sizeof(priv->data_buffer), 0);

	tpm_put_ops(priv->chip);
	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 + (120 * HZ));

	return in_size;
}

/*
 * Called on file close
 */
void tpm_common_release(struct file *file, struct file_priv *priv)
{
	del_singleshot_timer_sync(&priv->user_read_timer);
	flush_work(&priv->work);
	file->private_data = NULL;
	atomic_set(&priv->data_pending, 0);
}