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 #include "tpm-dev.h"
24
user_reader_timeout(struct timer_list * t)25 static void user_reader_timeout(struct timer_list *t)
26 {
27 struct file_priv *priv = from_timer(priv, t, user_read_timer);
28
29 pr_warn("TPM user space timeout is deprecated (pid=%d)\n",
30 task_tgid_nr(current));
31
32 schedule_work(&priv->work);
33 }
34
timeout_work(struct work_struct * work)35 static void timeout_work(struct work_struct *work)
36 {
37 struct file_priv *priv = container_of(work, struct file_priv, work);
38
39 mutex_lock(&priv->buffer_mutex);
40 priv->data_pending = 0;
41 memset(priv->data_buffer, 0, sizeof(priv->data_buffer));
42 mutex_unlock(&priv->buffer_mutex);
43 }
44
tpm_common_open(struct file * file,struct tpm_chip * chip,struct file_priv * priv)45 void tpm_common_open(struct file *file, struct tpm_chip *chip,
46 struct file_priv *priv)
47 {
48 priv->chip = chip;
49 mutex_init(&priv->buffer_mutex);
50 timer_setup(&priv->user_read_timer, user_reader_timeout, 0);
51 INIT_WORK(&priv->work, timeout_work);
52
53 file->private_data = priv;
54 }
55
tpm_common_read(struct file * file,char __user * buf,size_t size,loff_t * off)56 ssize_t tpm_common_read(struct file *file, char __user *buf,
57 size_t size, loff_t *off)
58 {
59 struct file_priv *priv = file->private_data;
60 ssize_t ret_size = 0;
61 int rc;
62
63 del_singleshot_timer_sync(&priv->user_read_timer);
64 flush_work(&priv->work);
65 mutex_lock(&priv->buffer_mutex);
66
67 if (priv->data_pending) {
68 ret_size = min_t(ssize_t, size, priv->data_pending);
69 rc = copy_to_user(buf, priv->data_buffer, ret_size);
70 memset(priv->data_buffer, 0, priv->data_pending);
71 if (rc)
72 ret_size = -EFAULT;
73
74 priv->data_pending = 0;
75 }
76
77 mutex_unlock(&priv->buffer_mutex);
78 return ret_size;
79 }
80
tpm_common_write(struct file * file,const char __user * buf,size_t size,loff_t * off,struct tpm_space * space)81 ssize_t tpm_common_write(struct file *file, const char __user *buf,
82 size_t size, loff_t *off, struct tpm_space *space)
83 {
84 struct file_priv *priv = file->private_data;
85 size_t in_size = size;
86 ssize_t out_size;
87
88 if (in_size > TPM_BUFSIZE)
89 return -E2BIG;
90
91 mutex_lock(&priv->buffer_mutex);
92
93 /* Cannot perform a write until the read has cleared either via
94 * tpm_read or a user_read_timer timeout. This also prevents split
95 * buffered writes from blocking here.
96 */
97 if (priv->data_pending != 0) {
98 mutex_unlock(&priv->buffer_mutex);
99 return -EBUSY;
100 }
101
102 if (copy_from_user
103 (priv->data_buffer, (void __user *) buf, in_size)) {
104 mutex_unlock(&priv->buffer_mutex);
105 return -EFAULT;
106 }
107
108 if (in_size < 6 ||
109 in_size < be32_to_cpu(*((__be32 *) (priv->data_buffer + 2)))) {
110 mutex_unlock(&priv->buffer_mutex);
111 return -EINVAL;
112 }
113
114 /* atomic tpm command send and result receive. We only hold the ops
115 * lock during this period so that the tpm can be unregistered even if
116 * the char dev is held open.
117 */
118 if (tpm_try_get_ops(priv->chip)) {
119 mutex_unlock(&priv->buffer_mutex);
120 return -EPIPE;
121 }
122 out_size = tpm_transmit(priv->chip, space, priv->data_buffer,
123 sizeof(priv->data_buffer), 0);
124
125 tpm_put_ops(priv->chip);
126 if (out_size < 0) {
127 mutex_unlock(&priv->buffer_mutex);
128 return out_size;
129 }
130
131 priv->data_pending = out_size;
132 mutex_unlock(&priv->buffer_mutex);
133
134 /* Set a timeout by which the reader must come claim the result */
135 mod_timer(&priv->user_read_timer, jiffies + (120 * HZ));
136
137 return in_size;
138 }
139
140 /*
141 * Called on file close
142 */
tpm_common_release(struct file * file,struct file_priv * priv)143 void tpm_common_release(struct file *file, struct file_priv *priv)
144 {
145 del_singleshot_timer_sync(&priv->user_read_timer);
146 flush_work(&priv->work);
147 file->private_data = NULL;
148 priv->data_pending = 0;
149 }
150