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 24 static ssize_t tpm_dev_transmit(struct tpm_chip *chip, struct tpm_space *space, 25 u8 *buf, size_t bufsiz) 26 { 27 struct tpm_header *header = (void *)buf; 28 ssize_t ret, len; 29 30 ret = tpm2_prepare_space(chip, space, buf, bufsiz); 31 /* If the command is not implemented by the TPM, synthesize a 32 * response with a TPM2_RC_COMMAND_CODE return for user-space. 33 */ 34 if (ret == -EOPNOTSUPP) { 35 header->length = cpu_to_be32(sizeof(*header)); 36 header->tag = cpu_to_be16(TPM2_ST_NO_SESSIONS); 37 header->return_code = cpu_to_be32(TPM2_RC_COMMAND_CODE | 38 TSS2_RESMGR_TPM_RC_LAYER); 39 ret = sizeof(*header); 40 } 41 if (ret) 42 goto out_rc; 43 44 len = tpm_transmit(chip, buf, bufsiz); 45 if (len < 0) 46 ret = len; 47 48 if (!ret) 49 ret = tpm2_commit_space(chip, space, buf, &len); 50 51 out_rc: 52 return ret ? ret : len; 53 } 54 55 static void tpm_dev_async_work(struct work_struct *work) 56 { 57 struct file_priv *priv = 58 container_of(work, struct file_priv, async_work); 59 ssize_t ret; 60 61 mutex_lock(&priv->buffer_mutex); 62 priv->command_enqueued = false; 63 ret = tpm_try_get_ops(priv->chip); 64 if (ret) { 65 priv->response_length = ret; 66 goto out; 67 } 68 69 ret = tpm_dev_transmit(priv->chip, priv->space, priv->data_buffer, 70 sizeof(priv->data_buffer)); 71 tpm_put_ops(priv->chip); 72 73 /* 74 * If ret is > 0 then tpm_dev_transmit returned the size of the 75 * response. If ret is < 0 then tpm_dev_transmit failed and 76 * returned an error code. 77 */ 78 if (ret != 0) { 79 priv->response_length = ret; 80 mod_timer(&priv->user_read_timer, jiffies + (120 * HZ)); 81 } 82 out: 83 mutex_unlock(&priv->buffer_mutex); 84 wake_up_interruptible(&priv->async_wait); 85 } 86 87 static void user_reader_timeout(struct timer_list *t) 88 { 89 struct file_priv *priv = from_timer(priv, t, user_read_timer); 90 91 pr_warn("TPM user space timeout is deprecated (pid=%d)\n", 92 task_tgid_nr(current)); 93 94 schedule_work(&priv->timeout_work); 95 } 96 97 static void tpm_timeout_work(struct work_struct *work) 98 { 99 struct file_priv *priv = container_of(work, struct file_priv, 100 timeout_work); 101 102 mutex_lock(&priv->buffer_mutex); 103 priv->response_read = true; 104 priv->response_length = 0; 105 memset(priv->data_buffer, 0, sizeof(priv->data_buffer)); 106 mutex_unlock(&priv->buffer_mutex); 107 wake_up_interruptible(&priv->async_wait); 108 } 109 110 void tpm_common_open(struct file *file, struct tpm_chip *chip, 111 struct file_priv *priv, struct tpm_space *space) 112 { 113 priv->chip = chip; 114 priv->space = space; 115 priv->response_read = true; 116 117 mutex_init(&priv->buffer_mutex); 118 timer_setup(&priv->user_read_timer, user_reader_timeout, 0); 119 INIT_WORK(&priv->timeout_work, tpm_timeout_work); 120 INIT_WORK(&priv->async_work, tpm_dev_async_work); 121 init_waitqueue_head(&priv->async_wait); 122 file->private_data = priv; 123 } 124 125 ssize_t tpm_common_read(struct file *file, char __user *buf, 126 size_t size, loff_t *off) 127 { 128 struct file_priv *priv = file->private_data; 129 ssize_t ret_size = 0; 130 int rc; 131 132 mutex_lock(&priv->buffer_mutex); 133 134 if (priv->response_length) { 135 priv->response_read = true; 136 137 ret_size = min_t(ssize_t, size, priv->response_length); 138 if (ret_size <= 0) { 139 priv->response_length = 0; 140 goto out; 141 } 142 143 rc = copy_to_user(buf, priv->data_buffer + *off, ret_size); 144 if (rc) { 145 memset(priv->data_buffer, 0, TPM_BUFSIZE); 146 priv->response_length = 0; 147 ret_size = -EFAULT; 148 } else { 149 memset(priv->data_buffer + *off, 0, ret_size); 150 priv->response_length -= ret_size; 151 *off += ret_size; 152 } 153 } 154 155 out: 156 if (!priv->response_length) { 157 *off = 0; 158 del_singleshot_timer_sync(&priv->user_read_timer); 159 flush_work(&priv->timeout_work); 160 } 161 mutex_unlock(&priv->buffer_mutex); 162 return ret_size; 163 } 164 165 ssize_t tpm_common_write(struct file *file, const char __user *buf, 166 size_t size, loff_t *off) 167 { 168 struct file_priv *priv = file->private_data; 169 int ret = 0; 170 171 if (size > TPM_BUFSIZE) 172 return -E2BIG; 173 174 mutex_lock(&priv->buffer_mutex); 175 176 /* Cannot perform a write until the read has cleared either via 177 * tpm_read or a user_read_timer timeout. This also prevents split 178 * buffered writes from blocking here. 179 */ 180 if ((!priv->response_read && priv->response_length) || 181 priv->command_enqueued) { 182 ret = -EBUSY; 183 goto out; 184 } 185 186 if (copy_from_user(priv->data_buffer, buf, size)) { 187 ret = -EFAULT; 188 goto out; 189 } 190 191 if (size < 6 || 192 size < be32_to_cpu(*((__be32 *)(priv->data_buffer + 2)))) { 193 ret = -EINVAL; 194 goto out; 195 } 196 197 priv->response_length = 0; 198 priv->response_read = false; 199 *off = 0; 200 201 /* 202 * If in nonblocking mode schedule an async job to send 203 * the command return the size. 204 * In case of error the err code will be returned in 205 * the subsequent read call. 206 */ 207 if (file->f_flags & O_NONBLOCK) { 208 priv->command_enqueued = true; 209 queue_work(tpm_dev_wq, &priv->async_work); 210 mutex_unlock(&priv->buffer_mutex); 211 return size; 212 } 213 214 /* atomic tpm command send and result receive. We only hold the ops 215 * lock during this period so that the tpm can be unregistered even if 216 * the char dev is held open. 217 */ 218 if (tpm_try_get_ops(priv->chip)) { 219 ret = -EPIPE; 220 goto out; 221 } 222 223 ret = tpm_dev_transmit(priv->chip, priv->space, priv->data_buffer, 224 sizeof(priv->data_buffer)); 225 tpm_put_ops(priv->chip); 226 227 if (ret > 0) { 228 priv->response_length = ret; 229 mod_timer(&priv->user_read_timer, jiffies + (120 * HZ)); 230 ret = size; 231 } 232 out: 233 mutex_unlock(&priv->buffer_mutex); 234 return ret; 235 } 236 237 __poll_t tpm_common_poll(struct file *file, poll_table *wait) 238 { 239 struct file_priv *priv = file->private_data; 240 __poll_t mask = 0; 241 242 poll_wait(file, &priv->async_wait, wait); 243 mutex_lock(&priv->buffer_mutex); 244 245 /* 246 * The response_length indicates if there is still response 247 * (or part of it) to be consumed. Partial reads decrease it 248 * by the number of bytes read, and write resets it the zero. 249 */ 250 if (priv->response_length) 251 mask = EPOLLIN | EPOLLRDNORM; 252 else 253 mask = EPOLLOUT | EPOLLWRNORM; 254 255 mutex_unlock(&priv->buffer_mutex); 256 return mask; 257 } 258 259 /* 260 * Called on file close 261 */ 262 void tpm_common_release(struct file *file, struct file_priv *priv) 263 { 264 flush_work(&priv->async_work); 265 del_singleshot_timer_sync(&priv->user_read_timer); 266 flush_work(&priv->timeout_work); 267 file->private_data = NULL; 268 priv->response_length = 0; 269 } 270 271 int __init tpm_dev_common_init(void) 272 { 273 tpm_dev_wq = alloc_workqueue("tpm_dev_wq", WQ_MEM_RECLAIM, 0); 274 275 return !tpm_dev_wq ? -ENOMEM : 0; 276 } 277 278 void __exit tpm_dev_common_exit(void) 279 { 280 if (tpm_dev_wq) { 281 destroy_workqueue(tpm_dev_wq); 282 tpm_dev_wq = NULL; 283 } 284 } 285