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01325476 S |
1 | /* |
2 | * An implementation of file copy service. | |
3 | * | |
4 | * Copyright (C) 2014, Microsoft, Inc. | |
5 | * | |
6 | * Author : K. Y. Srinivasan <ksrinivasan@novell.com> | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or modify it | |
9 | * under the terms of the GNU General Public License version 2 as published | |
10 | * by the Free Software Foundation. | |
11 | * | |
12 | * This program is distributed in the hope that it will be useful, but | |
13 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or | |
15 | * NON INFRINGEMENT. See the GNU General Public License for more | |
16 | * details. | |
17 | * | |
18 | */ | |
19 | ||
20 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
21 | ||
22 | #include <linux/semaphore.h> | |
23 | #include <linux/fs.h> | |
24 | #include <linux/nls.h> | |
25 | #include <linux/workqueue.h> | |
26 | #include <linux/cdev.h> | |
27 | #include <linux/hyperv.h> | |
28 | #include <linux/sched.h> | |
29 | #include <linux/uaccess.h> | |
30 | #include <linux/miscdevice.h> | |
31 | ||
32 | #include "hyperv_vmbus.h" | |
33 | ||
34 | #define WIN8_SRV_MAJOR 1 | |
35 | #define WIN8_SRV_MINOR 1 | |
36 | #define WIN8_SRV_VERSION (WIN8_SRV_MAJOR << 16 | WIN8_SRV_MINOR) | |
37 | ||
38 | /* | |
39 | * Global state maintained for transaction that is being processed. | |
40 | * For a class of integration services, including the "file copy service", | |
41 | * the specified protocol is a "request/response" protocol which means that | |
42 | * there can only be single outstanding transaction from the host at any | |
43 | * given point in time. We use this to simplify memory management in this | |
44 | * driver - we cache and process only one message at a time. | |
45 | * | |
46 | * While the request/response protocol is guaranteed by the host, we further | |
47 | * ensure this by serializing packet processing in this driver - we do not | |
48 | * read additional packets from the VMBUs until the current packet is fully | |
49 | * handled. | |
50 | * | |
51 | * The transaction "active" state is set when we receive a request from the | |
52 | * host and we cleanup this state when the transaction is completed - when we | |
53 | * respond to the host with our response. When the transaction active state is | |
54 | * set, we defer handling incoming packets. | |
55 | */ | |
56 | ||
57 | static struct { | |
58 | bool active; /* transaction status - active or not */ | |
59 | int recv_len; /* number of bytes received. */ | |
60 | struct hv_fcopy_hdr *fcopy_msg; /* current message */ | |
61 | struct hv_start_fcopy message; /* sent to daemon */ | |
62 | struct vmbus_channel *recv_channel; /* chn we got the request */ | |
63 | u64 recv_req_id; /* request ID. */ | |
64 | void *fcopy_context; /* for the channel callback */ | |
65 | struct semaphore read_sema; | |
66 | } fcopy_transaction; | |
67 | ||
68 | static bool opened; /* currently device opened */ | |
69 | ||
70 | /* | |
71 | * Before we can accept copy messages from the host, we need | |
72 | * to handshake with the user level daemon. This state tracks | |
73 | * if we are in the handshake phase. | |
74 | */ | |
75 | static bool in_hand_shake = true; | |
76 | static void fcopy_send_data(void); | |
77 | static void fcopy_respond_to_host(int error); | |
78 | static void fcopy_work_func(struct work_struct *dummy); | |
79 | static DECLARE_DELAYED_WORK(fcopy_work, fcopy_work_func); | |
80 | static u8 *recv_buffer; | |
81 | ||
82 | static void fcopy_work_func(struct work_struct *dummy) | |
83 | { | |
84 | /* | |
85 | * If the timer fires, the user-mode component has not responded; | |
86 | * process the pending transaction. | |
87 | */ | |
88 | fcopy_respond_to_host(HV_E_FAIL); | |
d9b16529 DC |
89 | |
90 | /* In the case the user-space daemon crashes, hangs or is killed, we | |
91 | * need to down the semaphore, otherwise, after the daemon starts next | |
92 | * time, the obsolete data in fcopy_transaction.message or | |
93 | * fcopy_transaction.fcopy_msg will be used immediately. | |
94 | * | |
95 | * NOTE: fcopy_read() happens to get the semaphore (very rare)? We're | |
96 | * still OK, because we've reported the failure to the host. | |
97 | */ | |
98 | if (down_trylock(&fcopy_transaction.read_sema)) | |
99 | ; | |
100 | ||
01325476 S |
101 | } |
102 | ||
103 | static int fcopy_handle_handshake(u32 version) | |
104 | { | |
105 | switch (version) { | |
106 | case FCOPY_CURRENT_VERSION: | |
107 | break; | |
108 | default: | |
109 | /* | |
110 | * For now we will fail the registration. | |
111 | * If and when we have multiple versions to | |
112 | * deal with, we will be backward compatible. | |
113 | * We will add this code when needed. | |
114 | */ | |
115 | return -EINVAL; | |
116 | } | |
117 | pr_info("FCP: user-mode registering done. Daemon version: %d\n", | |
118 | version); | |
119 | fcopy_transaction.active = false; | |
120 | if (fcopy_transaction.fcopy_context) | |
121 | hv_fcopy_onchannelcallback(fcopy_transaction.fcopy_context); | |
122 | in_hand_shake = false; | |
123 | return 0; | |
124 | } | |
125 | ||
126 | static void fcopy_send_data(void) | |
127 | { | |
128 | struct hv_start_fcopy *smsg_out = &fcopy_transaction.message; | |
129 | int operation = fcopy_transaction.fcopy_msg->operation; | |
130 | struct hv_start_fcopy *smsg_in; | |
131 | ||
132 | /* | |
133 | * The strings sent from the host are encoded in | |
134 | * in utf16; convert it to utf8 strings. | |
135 | * The host assures us that the utf16 strings will not exceed | |
136 | * the max lengths specified. We will however, reserve room | |
137 | * for the string terminating character - in the utf16s_utf8s() | |
138 | * function we limit the size of the buffer where the converted | |
139 | * string is placed to W_MAX_PATH -1 to guarantee | |
140 | * that the strings can be properly terminated! | |
141 | */ | |
142 | ||
143 | switch (operation) { | |
144 | case START_FILE_COPY: | |
145 | memset(smsg_out, 0, sizeof(struct hv_start_fcopy)); | |
146 | smsg_out->hdr.operation = operation; | |
147 | smsg_in = (struct hv_start_fcopy *)fcopy_transaction.fcopy_msg; | |
148 | ||
149 | utf16s_to_utf8s((wchar_t *)smsg_in->file_name, W_MAX_PATH, | |
150 | UTF16_LITTLE_ENDIAN, | |
151 | (__u8 *)smsg_out->file_name, W_MAX_PATH - 1); | |
152 | ||
153 | utf16s_to_utf8s((wchar_t *)smsg_in->path_name, W_MAX_PATH, | |
154 | UTF16_LITTLE_ENDIAN, | |
155 | (__u8 *)smsg_out->path_name, W_MAX_PATH - 1); | |
156 | ||
157 | smsg_out->copy_flags = smsg_in->copy_flags; | |
158 | smsg_out->file_size = smsg_in->file_size; | |
159 | break; | |
160 | ||
161 | default: | |
162 | break; | |
163 | } | |
164 | up(&fcopy_transaction.read_sema); | |
165 | return; | |
166 | } | |
167 | ||
168 | /* | |
169 | * Send a response back to the host. | |
170 | */ | |
171 | ||
172 | static void | |
173 | fcopy_respond_to_host(int error) | |
174 | { | |
175 | struct icmsg_hdr *icmsghdr; | |
176 | u32 buf_len; | |
177 | struct vmbus_channel *channel; | |
178 | u64 req_id; | |
179 | ||
180 | /* | |
181 | * Copy the global state for completing the transaction. Note that | |
182 | * only one transaction can be active at a time. This is guaranteed | |
183 | * by the file copy protocol implemented by the host. Furthermore, | |
184 | * the "transaction active" state we maintain ensures that there can | |
185 | * only be one active transaction at a time. | |
186 | */ | |
187 | ||
188 | buf_len = fcopy_transaction.recv_len; | |
189 | channel = fcopy_transaction.recv_channel; | |
190 | req_id = fcopy_transaction.recv_req_id; | |
191 | ||
192 | fcopy_transaction.active = false; | |
193 | ||
194 | icmsghdr = (struct icmsg_hdr *) | |
195 | &recv_buffer[sizeof(struct vmbuspipe_hdr)]; | |
196 | ||
197 | if (channel->onchannel_callback == NULL) | |
198 | /* | |
199 | * We have raced with util driver being unloaded; | |
200 | * silently return. | |
201 | */ | |
202 | return; | |
203 | ||
204 | icmsghdr->status = error; | |
205 | icmsghdr->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE; | |
206 | vmbus_sendpacket(channel, recv_buffer, buf_len, req_id, | |
207 | VM_PKT_DATA_INBAND, 0); | |
208 | } | |
209 | ||
210 | void hv_fcopy_onchannelcallback(void *context) | |
211 | { | |
212 | struct vmbus_channel *channel = context; | |
213 | u32 recvlen; | |
214 | u64 requestid; | |
215 | struct hv_fcopy_hdr *fcopy_msg; | |
216 | struct icmsg_hdr *icmsghdr; | |
217 | struct icmsg_negotiate *negop = NULL; | |
218 | int util_fw_version; | |
219 | int fcopy_srv_version; | |
220 | ||
221 | if (fcopy_transaction.active) { | |
222 | /* | |
223 | * We will defer processing this callback once | |
224 | * the current transaction is complete. | |
225 | */ | |
226 | fcopy_transaction.fcopy_context = context; | |
227 | return; | |
228 | } | |
229 | ||
230 | vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen, | |
231 | &requestid); | |
232 | if (recvlen <= 0) | |
233 | return; | |
234 | ||
235 | icmsghdr = (struct icmsg_hdr *)&recv_buffer[ | |
236 | sizeof(struct vmbuspipe_hdr)]; | |
237 | if (icmsghdr->icmsgtype == ICMSGTYPE_NEGOTIATE) { | |
238 | util_fw_version = UTIL_FW_VERSION; | |
239 | fcopy_srv_version = WIN8_SRV_VERSION; | |
240 | vmbus_prep_negotiate_resp(icmsghdr, negop, recv_buffer, | |
241 | util_fw_version, fcopy_srv_version); | |
242 | } else { | |
243 | fcopy_msg = (struct hv_fcopy_hdr *)&recv_buffer[ | |
244 | sizeof(struct vmbuspipe_hdr) + | |
245 | sizeof(struct icmsg_hdr)]; | |
246 | ||
247 | /* | |
248 | * Stash away this global state for completing the | |
249 | * transaction; note transactions are serialized. | |
250 | */ | |
251 | ||
252 | fcopy_transaction.active = true; | |
253 | fcopy_transaction.recv_len = recvlen; | |
254 | fcopy_transaction.recv_channel = channel; | |
255 | fcopy_transaction.recv_req_id = requestid; | |
256 | fcopy_transaction.fcopy_msg = fcopy_msg; | |
257 | ||
258 | /* | |
259 | * Send the information to the user-level daemon. | |
260 | */ | |
01325476 | 261 | schedule_delayed_work(&fcopy_work, 5*HZ); |
2ef82d24 | 262 | fcopy_send_data(); |
01325476 S |
263 | return; |
264 | } | |
265 | icmsghdr->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE; | |
266 | vmbus_sendpacket(channel, recv_buffer, recvlen, requestid, | |
267 | VM_PKT_DATA_INBAND, 0); | |
268 | } | |
269 | ||
270 | /* | |
271 | * Create a char device that can support read/write for passing | |
272 | * the payload. | |
273 | */ | |
274 | ||
275 | static ssize_t fcopy_read(struct file *file, char __user *buf, | |
276 | size_t count, loff_t *ppos) | |
277 | { | |
278 | void *src; | |
279 | size_t copy_size; | |
280 | int operation; | |
281 | ||
282 | /* | |
283 | * Wait until there is something to be read. | |
284 | */ | |
285 | if (down_interruptible(&fcopy_transaction.read_sema)) | |
286 | return -EINTR; | |
287 | ||
288 | /* | |
289 | * The channel may be rescinded and in this case, we will wakeup the | |
290 | * the thread blocked on the semaphore and we will use the opened | |
291 | * state to correctly handle this case. | |
292 | */ | |
293 | if (!opened) | |
294 | return -ENODEV; | |
295 | ||
296 | operation = fcopy_transaction.fcopy_msg->operation; | |
297 | ||
298 | if (operation == START_FILE_COPY) { | |
299 | src = &fcopy_transaction.message; | |
300 | copy_size = sizeof(struct hv_start_fcopy); | |
301 | if (count < copy_size) | |
302 | return 0; | |
303 | } else { | |
304 | src = fcopy_transaction.fcopy_msg; | |
305 | copy_size = sizeof(struct hv_do_fcopy); | |
306 | if (count < copy_size) | |
307 | return 0; | |
308 | } | |
309 | if (copy_to_user(buf, src, copy_size)) | |
310 | return -EFAULT; | |
311 | ||
312 | return copy_size; | |
313 | } | |
314 | ||
315 | static ssize_t fcopy_write(struct file *file, const char __user *buf, | |
316 | size_t count, loff_t *ppos) | |
317 | { | |
318 | int response = 0; | |
319 | ||
320 | if (count != sizeof(int)) | |
321 | return -EINVAL; | |
322 | ||
323 | if (copy_from_user(&response, buf, sizeof(int))) | |
324 | return -EFAULT; | |
325 | ||
326 | if (in_hand_shake) { | |
327 | if (fcopy_handle_handshake(response)) | |
328 | return -EINVAL; | |
329 | return sizeof(int); | |
330 | } | |
331 | ||
332 | /* | |
333 | * Complete the transaction by forwarding the result | |
334 | * to the host. But first, cancel the timeout. | |
335 | */ | |
336 | if (cancel_delayed_work_sync(&fcopy_work)) | |
337 | fcopy_respond_to_host(response); | |
338 | ||
339 | return sizeof(int); | |
340 | } | |
341 | ||
c765a6df | 342 | static int fcopy_open(struct inode *inode, struct file *f) |
01325476 S |
343 | { |
344 | /* | |
345 | * The user level daemon that will open this device is | |
346 | * really an extension of this driver. We can have only | |
347 | * active open at a time. | |
348 | */ | |
349 | if (opened) | |
350 | return -EBUSY; | |
351 | ||
352 | /* | |
353 | * The daemon is alive; setup the state. | |
354 | */ | |
355 | opened = true; | |
356 | return 0; | |
357 | } | |
358 | ||
d9b16529 DC |
359 | /* XXX: there are still some tricky corner cases, e.g., |
360 | * 1) In a SMP guest, when fcopy_release() runs between | |
361 | * schedule_delayed_work() and fcopy_send_data(), there is | |
362 | * still a chance an obsolete message will be queued. | |
363 | * | |
364 | * 2) When the fcopy daemon is running, if we unload the driver, | |
365 | * we'll notice a kernel oops when we kill the daemon later. | |
366 | */ | |
c765a6df | 367 | static int fcopy_release(struct inode *inode, struct file *f) |
01325476 S |
368 | { |
369 | /* | |
370 | * The daemon has exited; reset the state. | |
371 | */ | |
372 | in_hand_shake = true; | |
373 | opened = false; | |
d9b16529 DC |
374 | |
375 | if (cancel_delayed_work_sync(&fcopy_work)) { | |
376 | /* We haven't up()-ed the semaphore(very rare)? */ | |
377 | if (down_trylock(&fcopy_transaction.read_sema)) | |
378 | ; | |
379 | fcopy_respond_to_host(HV_E_FAIL); | |
380 | } | |
01325476 S |
381 | return 0; |
382 | } | |
383 | ||
384 | ||
385 | static const struct file_operations fcopy_fops = { | |
386 | .read = fcopy_read, | |
387 | .write = fcopy_write, | |
388 | .release = fcopy_release, | |
389 | .open = fcopy_open, | |
390 | }; | |
391 | ||
392 | static struct miscdevice fcopy_misc = { | |
393 | .minor = MISC_DYNAMIC_MINOR, | |
394 | .name = "vmbus/hv_fcopy", | |
395 | .fops = &fcopy_fops, | |
396 | }; | |
397 | ||
398 | static int fcopy_dev_init(void) | |
399 | { | |
400 | return misc_register(&fcopy_misc); | |
401 | } | |
402 | ||
403 | static void fcopy_dev_deinit(void) | |
404 | { | |
405 | ||
406 | /* | |
407 | * The device is going away - perhaps because the | |
408 | * host has rescinded the channel. Setup state so that | |
409 | * user level daemon can gracefully exit if it is blocked | |
410 | * on the read semaphore. | |
411 | */ | |
412 | opened = false; | |
413 | /* | |
414 | * Signal the semaphore as the device is | |
415 | * going away. | |
416 | */ | |
417 | up(&fcopy_transaction.read_sema); | |
418 | misc_deregister(&fcopy_misc); | |
419 | } | |
420 | ||
421 | int hv_fcopy_init(struct hv_util_service *srv) | |
422 | { | |
423 | recv_buffer = srv->recv_buffer; | |
424 | ||
425 | /* | |
426 | * When this driver loads, the user level daemon that | |
427 | * processes the host requests may not yet be running. | |
428 | * Defer processing channel callbacks until the daemon | |
429 | * has registered. | |
430 | */ | |
431 | fcopy_transaction.active = true; | |
432 | sema_init(&fcopy_transaction.read_sema, 0); | |
433 | ||
434 | return fcopy_dev_init(); | |
435 | } | |
436 | ||
437 | void hv_fcopy_deinit(void) | |
438 | { | |
439 | cancel_delayed_work_sync(&fcopy_work); | |
440 | fcopy_dev_deinit(); | |
441 | } |