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