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/poll.h> 21 #include <linux/slab.h> 22 #include <linux/uaccess.h> 23 #include <linux/workqueue.h> 24 #include "tpm.h" 25 #include "tpm-dev.h" 26 27 static struct workqueue_struct *tpm_dev_wq; 28 static DEFINE_MUTEX(tpm_dev_wq_lock); 29 30 static ssize_t tpm_dev_transmit(struct tpm_chip *chip, struct tpm_space *space, 31 u8 *buf, size_t bufsiz) 32 { 33 struct tpm_header *header = (void *)buf; 34 ssize_t ret, len; 35 36 ret = tpm2_prepare_space(chip, space, buf, bufsiz); 37 /* If the command is not implemented by the TPM, synthesize a 38 * response with a TPM2_RC_COMMAND_CODE return for user-space. 39 */ 40 if (ret == -EOPNOTSUPP) { 41 header->length = cpu_to_be32(sizeof(*header)); 42 header->tag = cpu_to_be16(TPM2_ST_NO_SESSIONS); 43 header->return_code = cpu_to_be32(TPM2_RC_COMMAND_CODE | 44 TSS2_RESMGR_TPM_RC_LAYER); 45 ret = sizeof(*header); 46 } 47 if (ret) 48 goto out_rc; 49 50 len = tpm_transmit(chip, buf, bufsiz); 51 if (len < 0) 52 ret = len; 53 54 if (!ret) 55 ret = tpm2_commit_space(chip, space, buf, &len); 56 57 out_rc: 58 return ret ? ret : len; 59 } 60 61 static void tpm_dev_async_work(struct work_struct *work) 62 { 63 struct file_priv *priv = 64 container_of(work, struct file_priv, async_work); 65 ssize_t ret; 66 67 mutex_lock(&priv->buffer_mutex); 68 priv->command_enqueued = false; 69 ret = tpm_dev_transmit(priv->chip, priv->space, priv->data_buffer, 70 sizeof(priv->data_buffer)); 71 tpm_put_ops(priv->chip); 72 if (ret > 0) { 73 priv->response_length = ret; 74 mod_timer(&priv->user_read_timer, jiffies + (120 * HZ)); 75 } 76 mutex_unlock(&priv->buffer_mutex); 77 wake_up_interruptible(&priv->async_wait); 78 } 79 80 static void user_reader_timeout(struct timer_list *t) 81 { 82 struct file_priv *priv = from_timer(priv, t, user_read_timer); 83 84 pr_warn("TPM user space timeout is deprecated (pid=%d)\n", 85 task_tgid_nr(current)); 86 87 schedule_work(&priv->timeout_work); 88 } 89 90 static void tpm_timeout_work(struct work_struct *work) 91 { 92 struct file_priv *priv = container_of(work, struct file_priv, 93 timeout_work); 94 95 mutex_lock(&priv->buffer_mutex); 96 priv->response_read = true; 97 priv->response_length = 0; 98 memset(priv->data_buffer, 0, sizeof(priv->data_buffer)); 99 mutex_unlock(&priv->buffer_mutex); 100 wake_up_interruptible(&priv->async_wait); 101 } 102 103 void tpm_common_open(struct file *file, struct tpm_chip *chip, 104 struct file_priv *priv, struct tpm_space *space) 105 { 106 priv->chip = chip; 107 priv->space = space; 108 priv->response_read = true; 109 110 mutex_init(&priv->buffer_mutex); 111 timer_setup(&priv->user_read_timer, user_reader_timeout, 0); 112 INIT_WORK(&priv->timeout_work, tpm_timeout_work); 113 INIT_WORK(&priv->async_work, tpm_dev_async_work); 114 init_waitqueue_head(&priv->async_wait); 115 file->private_data = priv; 116 } 117 118 ssize_t tpm_common_read(struct file *file, char __user *buf, 119 size_t size, loff_t *off) 120 { 121 struct file_priv *priv = file->private_data; 122 ssize_t ret_size = 0; 123 int rc; 124 125 mutex_lock(&priv->buffer_mutex); 126 127 if (priv->response_length) { 128 priv->response_read = true; 129 130 ret_size = min_t(ssize_t, size, priv->response_length); 131 if (!ret_size) { 132 priv->response_length = 0; 133 goto out; 134 } 135 136 rc = copy_to_user(buf, priv->data_buffer + *off, ret_size); 137 if (rc) { 138 memset(priv->data_buffer, 0, TPM_BUFSIZE); 139 priv->response_length = 0; 140 ret_size = -EFAULT; 141 } else { 142 memset(priv->data_buffer + *off, 0, ret_size); 143 priv->response_length -= ret_size; 144 *off += ret_size; 145 } 146 } 147 148 out: 149 if (!priv->response_length) { 150 *off = 0; 151 del_singleshot_timer_sync(&priv->user_read_timer); 152 flush_work(&priv->timeout_work); 153 } 154 mutex_unlock(&priv->buffer_mutex); 155 return ret_size; 156 } 157 158 ssize_t tpm_common_write(struct file *file, const char __user *buf, 159 size_t size, loff_t *off) 160 { 161 struct file_priv *priv = file->private_data; 162 int ret = 0; 163 164 if (size > TPM_BUFSIZE) 165 return -E2BIG; 166 167 mutex_lock(&priv->buffer_mutex); 168 169 /* Cannot perform a write until the read has cleared either via 170 * tpm_read or a user_read_timer timeout. This also prevents split 171 * buffered writes from blocking here. 172 */ 173 if ((!priv->response_read && priv->response_length) || 174 priv->command_enqueued) { 175 ret = -EBUSY; 176 goto out; 177 } 178 179 if (copy_from_user(priv->data_buffer, buf, size)) { 180 ret = -EFAULT; 181 goto out; 182 } 183 184 if (size < 6 || 185 size < be32_to_cpu(*((__be32 *)(priv->data_buffer + 2)))) { 186 ret = -EINVAL; 187 goto out; 188 } 189 190 /* atomic tpm command send and result receive. We only hold the ops 191 * lock during this period so that the tpm can be unregistered even if 192 * the char dev is held open. 193 */ 194 if (tpm_try_get_ops(priv->chip)) { 195 ret = -EPIPE; 196 goto out; 197 } 198 199 priv->response_length = 0; 200 priv->response_read = false; 201 *off = 0; 202 203 /* 204 * If in nonblocking mode schedule an async job to send 205 * the command return the size. 206 * In case of error the err code will be returned in 207 * the subsequent read call. 208 */ 209 if (file->f_flags & O_NONBLOCK) { 210 priv->command_enqueued = true; 211 queue_work(tpm_dev_wq, &priv->async_work); 212 mutex_unlock(&priv->buffer_mutex); 213 return size; 214 } 215 216 ret = tpm_dev_transmit(priv->chip, priv->space, priv->data_buffer, 217 sizeof(priv->data_buffer)); 218 tpm_put_ops(priv->chip); 219 220 if (ret > 0) { 221 priv->response_length = ret; 222 mod_timer(&priv->user_read_timer, jiffies + (120 * HZ)); 223 ret = size; 224 } 225 out: 226 mutex_unlock(&priv->buffer_mutex); 227 return ret; 228 } 229 230 __poll_t tpm_common_poll(struct file *file, poll_table *wait) 231 { 232 struct file_priv *priv = file->private_data; 233 __poll_t mask = 0; 234 235 poll_wait(file, &priv->async_wait, wait); 236 mutex_lock(&priv->buffer_mutex); 237 238 /* 239 * The response_length indicates if there is still response 240 * (or part of it) to be consumed. Partial reads decrease it 241 * by the number of bytes read, and write resets it the zero. 242 */ 243 if (priv->response_length) 244 mask = EPOLLIN | EPOLLRDNORM; 245 else 246 mask = EPOLLOUT | EPOLLWRNORM; 247 248 mutex_unlock(&priv->buffer_mutex); 249 return mask; 250 } 251 252 /* 253 * Called on file close 254 */ 255 void tpm_common_release(struct file *file, struct file_priv *priv) 256 { 257 flush_work(&priv->async_work); 258 del_singleshot_timer_sync(&priv->user_read_timer); 259 flush_work(&priv->timeout_work); 260 file->private_data = NULL; 261 priv->response_length = 0; 262 } 263 264 int __init tpm_dev_common_init(void) 265 { 266 tpm_dev_wq = alloc_workqueue("tpm_dev_wq", WQ_MEM_RECLAIM, 0); 267 268 return !tpm_dev_wq ? -ENOMEM : 0; 269 } 270 271 void __exit tpm_dev_common_exit(void) 272 { 273 if (tpm_dev_wq) { 274 destroy_workqueue(tpm_dev_wq); 275 tpm_dev_wq = NULL; 276 } 277 } 278