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