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/poll.h> 16 #include <linux/slab.h> 17 #include <linux/uaccess.h> 18 #include <linux/workqueue.h> 19 #include "tpm.h" 20 #include "tpm-dev.h" 21 22 static struct workqueue_struct *tpm_dev_wq; 23 static DEFINE_MUTEX(tpm_dev_wq_lock); 24 25 static ssize_t tpm_dev_transmit(struct tpm_chip *chip, struct tpm_space *space, 26 u8 *buf, size_t bufsiz) 27 { 28 struct tpm_header *header = (void *)buf; 29 ssize_t ret, len; 30 31 ret = tpm2_prepare_space(chip, space, buf, bufsiz); 32 /* If the command is not implemented by the TPM, synthesize a 33 * response with a TPM2_RC_COMMAND_CODE return for user-space. 34 */ 35 if (ret == -EOPNOTSUPP) { 36 header->length = cpu_to_be32(sizeof(*header)); 37 header->tag = cpu_to_be16(TPM2_ST_NO_SESSIONS); 38 header->return_code = cpu_to_be32(TPM2_RC_COMMAND_CODE | 39 TSS2_RESMGR_TPM_RC_LAYER); 40 ret = sizeof(*header); 41 } 42 if (ret) 43 goto out_rc; 44 45 len = tpm_transmit(chip, buf, bufsiz); 46 if (len < 0) 47 ret = len; 48 49 if (!ret) 50 ret = tpm2_commit_space(chip, space, buf, &len); 51 52 out_rc: 53 return ret ? ret : len; 54 } 55 56 static void tpm_dev_async_work(struct work_struct *work) 57 { 58 struct file_priv *priv = 59 container_of(work, struct file_priv, async_work); 60 ssize_t ret; 61 62 mutex_lock(&priv->buffer_mutex); 63 priv->command_enqueued = false; 64 ret = tpm_try_get_ops(priv->chip); 65 if (ret) { 66 priv->response_length = ret; 67 goto out; 68 } 69 70 ret = tpm_dev_transmit(priv->chip, priv->space, priv->data_buffer, 71 sizeof(priv->data_buffer)); 72 tpm_put_ops(priv->chip); 73 if (ret > 0) { 74 priv->response_length = ret; 75 mod_timer(&priv->user_read_timer, jiffies + (120 * HZ)); 76 } 77 out: 78 mutex_unlock(&priv->buffer_mutex); 79 wake_up_interruptible(&priv->async_wait); 80 } 81 82 static void user_reader_timeout(struct timer_list *t) 83 { 84 struct file_priv *priv = from_timer(priv, t, user_read_timer); 85 86 pr_warn("TPM user space timeout is deprecated (pid=%d)\n", 87 task_tgid_nr(current)); 88 89 schedule_work(&priv->timeout_work); 90 } 91 92 static void tpm_timeout_work(struct work_struct *work) 93 { 94 struct file_priv *priv = container_of(work, struct file_priv, 95 timeout_work); 96 97 mutex_lock(&priv->buffer_mutex); 98 priv->response_read = true; 99 priv->response_length = 0; 100 memset(priv->data_buffer, 0, sizeof(priv->data_buffer)); 101 mutex_unlock(&priv->buffer_mutex); 102 wake_up_interruptible(&priv->async_wait); 103 } 104 105 void tpm_common_open(struct file *file, struct tpm_chip *chip, 106 struct file_priv *priv, struct tpm_space *space) 107 { 108 priv->chip = chip; 109 priv->space = space; 110 priv->response_read = true; 111 112 mutex_init(&priv->buffer_mutex); 113 timer_setup(&priv->user_read_timer, user_reader_timeout, 0); 114 INIT_WORK(&priv->timeout_work, tpm_timeout_work); 115 INIT_WORK(&priv->async_work, tpm_dev_async_work); 116 init_waitqueue_head(&priv->async_wait); 117 file->private_data = priv; 118 } 119 120 ssize_t tpm_common_read(struct file *file, char __user *buf, 121 size_t size, loff_t *off) 122 { 123 struct file_priv *priv = file->private_data; 124 ssize_t ret_size = 0; 125 int rc; 126 127 mutex_lock(&priv->buffer_mutex); 128 129 if (priv->response_length) { 130 priv->response_read = true; 131 132 ret_size = min_t(ssize_t, size, priv->response_length); 133 if (ret_size <= 0) { 134 priv->response_length = 0; 135 goto out; 136 } 137 138 rc = copy_to_user(buf, priv->data_buffer + *off, ret_size); 139 if (rc) { 140 memset(priv->data_buffer, 0, TPM_BUFSIZE); 141 priv->response_length = 0; 142 ret_size = -EFAULT; 143 } else { 144 memset(priv->data_buffer + *off, 0, ret_size); 145 priv->response_length -= ret_size; 146 *off += ret_size; 147 } 148 } 149 150 out: 151 if (!priv->response_length) { 152 *off = 0; 153 del_singleshot_timer_sync(&priv->user_read_timer); 154 flush_work(&priv->timeout_work); 155 } 156 mutex_unlock(&priv->buffer_mutex); 157 return ret_size; 158 } 159 160 ssize_t tpm_common_write(struct file *file, const char __user *buf, 161 size_t size, loff_t *off) 162 { 163 struct file_priv *priv = file->private_data; 164 int ret = 0; 165 166 if (size > TPM_BUFSIZE) 167 return -E2BIG; 168 169 mutex_lock(&priv->buffer_mutex); 170 171 /* Cannot perform a write until the read has cleared either via 172 * tpm_read or a user_read_timer timeout. This also prevents split 173 * buffered writes from blocking here. 174 */ 175 if ((!priv->response_read && priv->response_length) || 176 priv->command_enqueued) { 177 ret = -EBUSY; 178 goto out; 179 } 180 181 if (copy_from_user(priv->data_buffer, buf, size)) { 182 ret = -EFAULT; 183 goto out; 184 } 185 186 if (size < 6 || 187 size < be32_to_cpu(*((__be32 *)(priv->data_buffer + 2)))) { 188 ret = -EINVAL; 189 goto out; 190 } 191 192 /* atomic tpm command send and result receive. We only hold the ops 193 * lock during this period so that the tpm can be unregistered even if 194 * the char dev is held open. 195 */ 196 if (tpm_try_get_ops(priv->chip)) { 197 ret = -EPIPE; 198 goto out; 199 } 200 201 priv->response_length = 0; 202 priv->response_read = false; 203 *off = 0; 204 205 /* 206 * If in nonblocking mode schedule an async job to send 207 * the command return the size. 208 * In case of error the err code will be returned in 209 * the subsequent read call. 210 */ 211 if (file->f_flags & O_NONBLOCK) { 212 priv->command_enqueued = true; 213 queue_work(tpm_dev_wq, &priv->async_work); 214 tpm_put_ops(priv->chip); 215 mutex_unlock(&priv->buffer_mutex); 216 return size; 217 } 218 219 ret = tpm_dev_transmit(priv->chip, priv->space, priv->data_buffer, 220 sizeof(priv->data_buffer)); 221 tpm_put_ops(priv->chip); 222 223 if (ret > 0) { 224 priv->response_length = ret; 225 mod_timer(&priv->user_read_timer, jiffies + (120 * HZ)); 226 ret = size; 227 } 228 out: 229 mutex_unlock(&priv->buffer_mutex); 230 return ret; 231 } 232 233 __poll_t tpm_common_poll(struct file *file, poll_table *wait) 234 { 235 struct file_priv *priv = file->private_data; 236 __poll_t mask = 0; 237 238 poll_wait(file, &priv->async_wait, wait); 239 mutex_lock(&priv->buffer_mutex); 240 241 /* 242 * The response_length indicates if there is still response 243 * (or part of it) to be consumed. Partial reads decrease it 244 * by the number of bytes read, and write resets it the zero. 245 */ 246 if (priv->response_length) 247 mask = EPOLLIN | EPOLLRDNORM; 248 else 249 mask = EPOLLOUT | EPOLLWRNORM; 250 251 mutex_unlock(&priv->buffer_mutex); 252 return mask; 253 } 254 255 /* 256 * Called on file close 257 */ 258 void tpm_common_release(struct file *file, struct file_priv *priv) 259 { 260 flush_work(&priv->async_work); 261 del_singleshot_timer_sync(&priv->user_read_timer); 262 flush_work(&priv->timeout_work); 263 file->private_data = NULL; 264 priv->response_length = 0; 265 } 266 267 int __init tpm_dev_common_init(void) 268 { 269 tpm_dev_wq = alloc_workqueue("tpm_dev_wq", WQ_MEM_RECLAIM, 0); 270 271 return !tpm_dev_wq ? -ENOMEM : 0; 272 } 273 274 void __exit tpm_dev_common_exit(void) 275 { 276 if (tpm_dev_wq) { 277 destroy_workqueue(tpm_dev_wq); 278 tpm_dev_wq = NULL; 279 } 280 } 281