Commit | Line | Data |
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355b0502 GKH |
1 | /* |
2 | * drivers/misc/logger.c | |
3 | * | |
4 | * A Logging Subsystem | |
5 | * | |
6 | * Copyright (C) 2007-2008 Google, Inc. | |
7 | * | |
8 | * Robert Love <rlove@google.com> | |
9 | * | |
10 | * This software is licensed under the terms of the GNU General Public | |
11 | * License version 2, as published by the Free Software Foundation, and | |
12 | * may be copied, distributed, and modified under those terms. | |
13 | * | |
14 | * This program is distributed in the hope that it will be useful, | |
15 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
17 | * GNU General Public License for more details. | |
18 | */ | |
19 | ||
c810a399 SK |
20 | #define pr_fmt(fmt) "logger: " fmt |
21 | ||
23687af9 | 22 | #include <linux/sched.h> |
355b0502 GKH |
23 | #include <linux/module.h> |
24 | #include <linux/fs.h> | |
25 | #include <linux/miscdevice.h> | |
26 | #include <linux/uaccess.h> | |
27 | #include <linux/poll.h> | |
c11a166c | 28 | #include <linux/slab.h> |
355b0502 | 29 | #include <linux/time.h> |
10b24199 | 30 | #include <linux/vmalloc.h> |
a27bb332 | 31 | #include <linux/aio.h> |
355b0502 GKH |
32 | #include "logger.h" |
33 | ||
34 | #include <asm/ioctls.h> | |
35 | ||
0edc6c6d | 36 | /** |
355b0502 | 37 | * struct logger_log - represents a specific log, such as 'main' or 'radio' |
0edc6c6d CJB |
38 | * @buffer: The actual ring buffer |
39 | * @misc: The "misc" device representing the log | |
40 | * @wq: The wait queue for @readers | |
41 | * @readers: This log's readers | |
42 | * @mutex: The mutex that protects the @buffer | |
43 | * @w_off: The current write head offset | |
44 | * @head: The head, or location that readers start reading at. | |
45 | * @size: The size of the log | |
46 | * @logs: The list of log channels | |
355b0502 GKH |
47 | * |
48 | * This structure lives from module insertion until module removal, so it does | |
49 | * not need additional reference counting. The structure is protected by the | |
50 | * mutex 'mutex'. | |
51 | */ | |
52 | struct logger_log { | |
0edc6c6d CJB |
53 | unsigned char *buffer; |
54 | struct miscdevice misc; | |
55 | wait_queue_head_t wq; | |
56 | struct list_head readers; | |
57 | struct mutex mutex; | |
58 | size_t w_off; | |
59 | size_t head; | |
60 | size_t size; | |
61 | struct list_head logs; | |
355b0502 GKH |
62 | }; |
63 | ||
10b24199 TB |
64 | static LIST_HEAD(log_list); |
65 | ||
66 | ||
0edc6c6d | 67 | /** |
355b0502 | 68 | * struct logger_reader - a logging device open for reading |
0edc6c6d CJB |
69 | * @log: The associated log |
70 | * @list: The associated entry in @logger_log's list | |
71 | * @r_off: The current read head offset. | |
0441bcf4 NK |
72 | * @r_all: Reader can read all entries |
73 | * @r_ver: Reader ABI version | |
355b0502 GKH |
74 | * |
75 | * This object lives from open to release, so we don't need additional | |
76 | * reference counting. The structure is protected by log->mutex. | |
77 | */ | |
78 | struct logger_reader { | |
0edc6c6d CJB |
79 | struct logger_log *log; |
80 | struct list_head list; | |
81 | size_t r_off; | |
0441bcf4 NK |
82 | bool r_all; |
83 | int r_ver; | |
355b0502 GKH |
84 | }; |
85 | ||
86 | /* logger_offset - returns index 'n' into the log via (optimized) modulus */ | |
e7f3eb0c | 87 | static size_t logger_offset(struct logger_log *log, size_t n) |
c626224d | 88 | { |
e7f3eb0c | 89 | return n & (log->size - 1); |
c626224d TB |
90 | } |
91 | ||
355b0502 GKH |
92 | |
93 | /* | |
94 | * file_get_log - Given a file structure, return the associated log | |
95 | * | |
96 | * This isn't aesthetic. We have several goals: | |
97 | * | |
277cdd01 MN |
98 | * 1) Need to quickly obtain the associated log during an I/O operation |
99 | * 2) Readers need to maintain state (logger_reader) | |
100 | * 3) Writers need to be very fast (open() should be a near no-op) | |
355b0502 GKH |
101 | * |
102 | * In the reader case, we can trivially go file->logger_reader->logger_log. | |
103 | * For a writer, we don't want to maintain a logger_reader, so we just go | |
104 | * file->logger_log. Thus what file->private_data points at depends on whether | |
105 | * or not the file was opened for reading. This function hides that dirtiness. | |
106 | */ | |
107 | static inline struct logger_log *file_get_log(struct file *file) | |
108 | { | |
109 | if (file->f_mode & FMODE_READ) { | |
110 | struct logger_reader *reader = file->private_data; | |
111 | return reader->log; | |
112 | } else | |
113 | return file->private_data; | |
114 | } | |
115 | ||
116 | /* | |
0441bcf4 NK |
117 | * get_entry_header - returns a pointer to the logger_entry header within |
118 | * 'log' starting at offset 'off'. A temporary logger_entry 'scratch' must | |
119 | * be provided. Typically the return value will be a pointer within | |
120 | * 'logger->buf'. However, a pointer to 'scratch' may be returned if | |
121 | * the log entry spans the end and beginning of the circular buffer. | |
122 | */ | |
123 | static struct logger_entry *get_entry_header(struct logger_log *log, | |
124 | size_t off, struct logger_entry *scratch) | |
125 | { | |
126 | size_t len = min(sizeof(struct logger_entry), log->size - off); | |
127 | if (len != sizeof(struct logger_entry)) { | |
128 | memcpy(((void *) scratch), log->buffer + off, len); | |
129 | memcpy(((void *) scratch) + len, log->buffer, | |
130 | sizeof(struct logger_entry) - len); | |
131 | return scratch; | |
132 | } | |
133 | ||
134 | return (struct logger_entry *) (log->buffer + off); | |
135 | } | |
136 | ||
137 | /* | |
138 | * get_entry_msg_len - Grabs the length of the message of the entry | |
139 | * starting from from 'off'. | |
355b0502 | 140 | * |
3bcfa431 TB |
141 | * An entry length is 2 bytes (16 bits) in host endian order. |
142 | * In the log, the length does not include the size of the log entry structure. | |
143 | * This function returns the size including the log entry structure. | |
144 | * | |
355b0502 GKH |
145 | * Caller needs to hold log->mutex. |
146 | */ | |
0441bcf4 | 147 | static __u32 get_entry_msg_len(struct logger_log *log, size_t off) |
355b0502 | 148 | { |
0441bcf4 NK |
149 | struct logger_entry scratch; |
150 | struct logger_entry *entry; | |
355b0502 | 151 | |
0441bcf4 NK |
152 | entry = get_entry_header(log, off, &scratch); |
153 | return entry->len; | |
154 | } | |
3bcfa431 | 155 | |
0441bcf4 NK |
156 | static size_t get_user_hdr_len(int ver) |
157 | { | |
158 | if (ver < 2) | |
159 | return sizeof(struct user_logger_entry_compat); | |
3bcfa431 | 160 | else |
0441bcf4 NK |
161 | return sizeof(struct logger_entry); |
162 | } | |
163 | ||
164 | static ssize_t copy_header_to_user(int ver, struct logger_entry *entry, | |
165 | char __user *buf) | |
166 | { | |
167 | void *hdr; | |
168 | size_t hdr_len; | |
169 | struct user_logger_entry_compat v1; | |
170 | ||
171 | if (ver < 2) { | |
172 | v1.len = entry->len; | |
173 | v1.__pad = 0; | |
174 | v1.pid = entry->pid; | |
175 | v1.tid = entry->tid; | |
176 | v1.sec = entry->sec; | |
177 | v1.nsec = entry->nsec; | |
178 | hdr = &v1; | |
179 | hdr_len = sizeof(struct user_logger_entry_compat); | |
180 | } else { | |
181 | hdr = entry; | |
182 | hdr_len = sizeof(struct logger_entry); | |
183 | } | |
355b0502 | 184 | |
0441bcf4 | 185 | return copy_to_user(buf, hdr, hdr_len); |
355b0502 GKH |
186 | } |
187 | ||
188 | /* | |
189 | * do_read_log_to_user - reads exactly 'count' bytes from 'log' into the | |
190 | * user-space buffer 'buf'. Returns 'count' on success. | |
191 | * | |
192 | * Caller must hold log->mutex. | |
193 | */ | |
194 | static ssize_t do_read_log_to_user(struct logger_log *log, | |
195 | struct logger_reader *reader, | |
196 | char __user *buf, | |
197 | size_t count) | |
198 | { | |
0441bcf4 NK |
199 | struct logger_entry scratch; |
200 | struct logger_entry *entry; | |
355b0502 | 201 | size_t len; |
0441bcf4 | 202 | size_t msg_start; |
355b0502 GKH |
203 | |
204 | /* | |
0441bcf4 NK |
205 | * First, copy the header to userspace, using the version of |
206 | * the header requested | |
207 | */ | |
208 | entry = get_entry_header(log, reader->r_off, &scratch); | |
209 | if (copy_header_to_user(reader->r_ver, entry, buf)) | |
210 | return -EFAULT; | |
211 | ||
212 | count -= get_user_hdr_len(reader->r_ver); | |
213 | buf += get_user_hdr_len(reader->r_ver); | |
214 | msg_start = logger_offset(log, | |
215 | reader->r_off + sizeof(struct logger_entry)); | |
216 | ||
217 | /* | |
218 | * We read from the msg in two disjoint operations. First, we read from | |
219 | * the current msg head offset up to 'count' bytes or to the end of | |
355b0502 GKH |
220 | * the log, whichever comes first. |
221 | */ | |
0441bcf4 NK |
222 | len = min(count, log->size - msg_start); |
223 | if (copy_to_user(buf, log->buffer + msg_start, len)) | |
355b0502 GKH |
224 | return -EFAULT; |
225 | ||
226 | /* | |
227 | * Second, we read any remaining bytes, starting back at the head of | |
228 | * the log. | |
229 | */ | |
230 | if (count != len) | |
231 | if (copy_to_user(buf + len, log->buffer, count - len)) | |
232 | return -EFAULT; | |
233 | ||
0441bcf4 NK |
234 | reader->r_off = logger_offset(log, reader->r_off + |
235 | sizeof(struct logger_entry) + count); | |
355b0502 | 236 | |
0441bcf4 NK |
237 | return count + get_user_hdr_len(reader->r_ver); |
238 | } | |
239 | ||
240 | /* | |
241 | * get_next_entry_by_uid - Starting at 'off', returns an offset into | |
242 | * 'log->buffer' which contains the first entry readable by 'euid' | |
243 | */ | |
244 | static size_t get_next_entry_by_uid(struct logger_log *log, | |
bd471258 | 245 | size_t off, kuid_t euid) |
0441bcf4 NK |
246 | { |
247 | while (off != log->w_off) { | |
248 | struct logger_entry *entry; | |
249 | struct logger_entry scratch; | |
250 | size_t next_len; | |
251 | ||
252 | entry = get_entry_header(log, off, &scratch); | |
253 | ||
bd471258 | 254 | if (uid_eq(entry->euid, euid)) |
0441bcf4 NK |
255 | return off; |
256 | ||
257 | next_len = sizeof(struct logger_entry) + entry->len; | |
258 | off = logger_offset(log, off + next_len); | |
259 | } | |
260 | ||
261 | return off; | |
355b0502 GKH |
262 | } |
263 | ||
264 | /* | |
265 | * logger_read - our log's read() method | |
266 | * | |
267 | * Behavior: | |
268 | * | |
277cdd01 MN |
269 | * - O_NONBLOCK works |
270 | * - If there are no log entries to read, blocks until log is written to | |
271 | * - Atomically reads exactly one log entry | |
355b0502 | 272 | * |
0441bcf4 | 273 | * Will set errno to EINVAL if read |
355b0502 GKH |
274 | * buffer is insufficient to hold next entry. |
275 | */ | |
276 | static ssize_t logger_read(struct file *file, char __user *buf, | |
277 | size_t count, loff_t *pos) | |
278 | { | |
279 | struct logger_reader *reader = file->private_data; | |
280 | struct logger_log *log = reader->log; | |
281 | ssize_t ret; | |
282 | DEFINE_WAIT(wait); | |
283 | ||
284 | start: | |
285 | while (1) { | |
c76c7ca3 TB |
286 | mutex_lock(&log->mutex); |
287 | ||
355b0502 GKH |
288 | prepare_to_wait(&log->wq, &wait, TASK_INTERRUPTIBLE); |
289 | ||
355b0502 GKH |
290 | ret = (log->w_off == reader->r_off); |
291 | mutex_unlock(&log->mutex); | |
292 | if (!ret) | |
293 | break; | |
294 | ||
295 | if (file->f_flags & O_NONBLOCK) { | |
296 | ret = -EAGAIN; | |
297 | break; | |
298 | } | |
299 | ||
300 | if (signal_pending(current)) { | |
301 | ret = -EINTR; | |
302 | break; | |
303 | } | |
304 | ||
305 | schedule(); | |
306 | } | |
307 | ||
308 | finish_wait(&log->wq, &wait); | |
309 | if (ret) | |
310 | return ret; | |
311 | ||
312 | mutex_lock(&log->mutex); | |
313 | ||
0441bcf4 NK |
314 | if (!reader->r_all) |
315 | reader->r_off = get_next_entry_by_uid(log, | |
316 | reader->r_off, current_euid()); | |
317 | ||
355b0502 GKH |
318 | /* is there still something to read or did we race? */ |
319 | if (unlikely(log->w_off == reader->r_off)) { | |
320 | mutex_unlock(&log->mutex); | |
321 | goto start; | |
322 | } | |
323 | ||
324 | /* get the size of the next entry */ | |
0441bcf4 NK |
325 | ret = get_user_hdr_len(reader->r_ver) + |
326 | get_entry_msg_len(log, reader->r_off); | |
355b0502 GKH |
327 | if (count < ret) { |
328 | ret = -EINVAL; | |
329 | goto out; | |
330 | } | |
331 | ||
332 | /* get exactly one entry from the log */ | |
333 | ret = do_read_log_to_user(log, reader, buf, ret); | |
334 | ||
335 | out: | |
336 | mutex_unlock(&log->mutex); | |
337 | ||
338 | return ret; | |
339 | } | |
340 | ||
341 | /* | |
342 | * get_next_entry - return the offset of the first valid entry at least 'len' | |
343 | * bytes after 'off'. | |
344 | * | |
345 | * Caller must hold log->mutex. | |
346 | */ | |
347 | static size_t get_next_entry(struct logger_log *log, size_t off, size_t len) | |
348 | { | |
349 | size_t count = 0; | |
350 | ||
351 | do { | |
0441bcf4 NK |
352 | size_t nr = sizeof(struct logger_entry) + |
353 | get_entry_msg_len(log, off); | |
c626224d | 354 | off = logger_offset(log, off + nr); |
355b0502 GKH |
355 | count += nr; |
356 | } while (count < len); | |
357 | ||
358 | return off; | |
359 | } | |
360 | ||
361 | /* | |
169c843a TB |
362 | * is_between - is a < c < b, accounting for wrapping of a, b, and c |
363 | * positions in the buffer | |
364 | * | |
365 | * That is, if a<b, check for c between a and b | |
366 | * and if a>b, check for c outside (not between) a and b | |
367 | * | |
368 | * |------- a xxxxxxxx b --------| | |
369 | * c^ | |
370 | * | |
371 | * |xxxxx b --------- a xxxxxxxxx| | |
372 | * c^ | |
373 | * or c^ | |
355b0502 | 374 | */ |
169c843a | 375 | static inline int is_between(size_t a, size_t b, size_t c) |
355b0502 | 376 | { |
169c843a TB |
377 | if (a < b) { |
378 | /* is c between a and b? */ | |
379 | if (a < c && c <= b) | |
355b0502 GKH |
380 | return 1; |
381 | } else { | |
169c843a TB |
382 | /* is c outside of b through a? */ |
383 | if (c <= b || a < c) | |
355b0502 GKH |
384 | return 1; |
385 | } | |
386 | ||
387 | return 0; | |
388 | } | |
389 | ||
390 | /* | |
391 | * fix_up_readers - walk the list of all readers and "fix up" any who were | |
392 | * lapped by the writer; also do the same for the default "start head". | |
393 | * We do this by "pulling forward" the readers and start head to the first | |
394 | * entry after the new write head. | |
395 | * | |
396 | * The caller needs to hold log->mutex. | |
397 | */ | |
398 | static void fix_up_readers(struct logger_log *log, size_t len) | |
399 | { | |
400 | size_t old = log->w_off; | |
c626224d | 401 | size_t new = logger_offset(log, old + len); |
355b0502 GKH |
402 | struct logger_reader *reader; |
403 | ||
169c843a | 404 | if (is_between(old, new, log->head)) |
355b0502 GKH |
405 | log->head = get_next_entry(log, log->head, len); |
406 | ||
407 | list_for_each_entry(reader, &log->readers, list) | |
169c843a | 408 | if (is_between(old, new, reader->r_off)) |
355b0502 GKH |
409 | reader->r_off = get_next_entry(log, reader->r_off, len); |
410 | } | |
411 | ||
412 | /* | |
413 | * do_write_log - writes 'len' bytes from 'buf' to 'log' | |
414 | * | |
415 | * The caller needs to hold log->mutex. | |
416 | */ | |
417 | static void do_write_log(struct logger_log *log, const void *buf, size_t count) | |
418 | { | |
419 | size_t len; | |
420 | ||
421 | len = min(count, log->size - log->w_off); | |
422 | memcpy(log->buffer + log->w_off, buf, len); | |
423 | ||
424 | if (count != len) | |
425 | memcpy(log->buffer, buf + len, count - len); | |
426 | ||
c626224d | 427 | log->w_off = logger_offset(log, log->w_off + count); |
355b0502 GKH |
428 | |
429 | } | |
430 | ||
431 | /* | |
432 | * do_write_log_user - writes 'len' bytes from the user-space buffer 'buf' to | |
433 | * the log 'log' | |
434 | * | |
435 | * The caller needs to hold log->mutex. | |
436 | * | |
437 | * Returns 'count' on success, negative error code on failure. | |
438 | */ | |
439 | static ssize_t do_write_log_from_user(struct logger_log *log, | |
440 | const void __user *buf, size_t count) | |
441 | { | |
442 | size_t len; | |
443 | ||
444 | len = min(count, log->size - log->w_off); | |
445 | if (len && copy_from_user(log->buffer + log->w_off, buf, len)) | |
446 | return -EFAULT; | |
447 | ||
448 | if (count != len) | |
449 | if (copy_from_user(log->buffer, buf + len, count - len)) | |
350a1955 TB |
450 | /* |
451 | * Note that by not updating w_off, this abandons the | |
452 | * portion of the new entry that *was* successfully | |
453 | * copied, just above. This is intentional to avoid | |
454 | * message corruption from missing fragments. | |
455 | */ | |
355b0502 GKH |
456 | return -EFAULT; |
457 | ||
c626224d | 458 | log->w_off = logger_offset(log, log->w_off + count); |
355b0502 GKH |
459 | |
460 | return count; | |
461 | } | |
462 | ||
463 | /* | |
464 | * logger_aio_write - our write method, implementing support for write(), | |
465 | * writev(), and aio_write(). Writes are our fast path, and we try to optimize | |
466 | * them above all else. | |
467 | */ | |
e7f3eb0c | 468 | static ssize_t logger_aio_write(struct kiocb *iocb, const struct iovec *iov, |
355b0502 GKH |
469 | unsigned long nr_segs, loff_t ppos) |
470 | { | |
471 | struct logger_log *log = file_get_log(iocb->ki_filp); | |
472 | size_t orig = log->w_off; | |
473 | struct logger_entry header; | |
474 | struct timespec now; | |
475 | ssize_t ret = 0; | |
476 | ||
477 | now = current_kernel_time(); | |
478 | ||
479 | header.pid = current->tgid; | |
480 | header.tid = current->pid; | |
481 | header.sec = now.tv_sec; | |
482 | header.nsec = now.tv_nsec; | |
0441bcf4 | 483 | header.euid = current_euid(); |
355b0502 | 484 | header.len = min_t(size_t, iocb->ki_left, LOGGER_ENTRY_MAX_PAYLOAD); |
0441bcf4 | 485 | header.hdr_size = sizeof(struct logger_entry); |
355b0502 GKH |
486 | |
487 | /* null writes succeed, return zero */ | |
488 | if (unlikely(!header.len)) | |
489 | return 0; | |
490 | ||
491 | mutex_lock(&log->mutex); | |
492 | ||
493 | /* | |
494 | * Fix up any readers, pulling them forward to the first readable | |
495 | * entry after (what will be) the new write offset. We do this now | |
496 | * because if we partially fail, we can end up with clobbered log | |
497 | * entries that encroach on readable buffer. | |
498 | */ | |
499 | fix_up_readers(log, sizeof(struct logger_entry) + header.len); | |
500 | ||
501 | do_write_log(log, &header, sizeof(struct logger_entry)); | |
502 | ||
503 | while (nr_segs-- > 0) { | |
504 | size_t len; | |
505 | ssize_t nr; | |
506 | ||
507 | /* figure out how much of this vector we can keep */ | |
508 | len = min_t(size_t, iov->iov_len, header.len - ret); | |
509 | ||
510 | /* write out this segment's payload */ | |
511 | nr = do_write_log_from_user(log, iov->iov_base, len); | |
512 | if (unlikely(nr < 0)) { | |
513 | log->w_off = orig; | |
514 | mutex_unlock(&log->mutex); | |
515 | return nr; | |
516 | } | |
517 | ||
518 | iov++; | |
519 | ret += nr; | |
520 | } | |
521 | ||
522 | mutex_unlock(&log->mutex); | |
523 | ||
524 | /* wake up any blocked readers */ | |
525 | wake_up_interruptible(&log->wq); | |
526 | ||
527 | return ret; | |
528 | } | |
529 | ||
10b24199 TB |
530 | static struct logger_log *get_log_from_minor(int minor) |
531 | { | |
532 | struct logger_log *log; | |
533 | ||
534 | list_for_each_entry(log, &log_list, logs) | |
535 | if (log->misc.minor == minor) | |
536 | return log; | |
537 | return NULL; | |
538 | } | |
355b0502 GKH |
539 | |
540 | /* | |
541 | * logger_open - the log's open() file operation | |
542 | * | |
543 | * Note how near a no-op this is in the write-only case. Keep it that way! | |
544 | */ | |
545 | static int logger_open(struct inode *inode, struct file *file) | |
546 | { | |
547 | struct logger_log *log; | |
548 | int ret; | |
549 | ||
550 | ret = nonseekable_open(inode, file); | |
551 | if (ret) | |
552 | return ret; | |
553 | ||
554 | log = get_log_from_minor(MINOR(inode->i_rdev)); | |
555 | if (!log) | |
556 | return -ENODEV; | |
557 | ||
558 | if (file->f_mode & FMODE_READ) { | |
559 | struct logger_reader *reader; | |
560 | ||
561 | reader = kmalloc(sizeof(struct logger_reader), GFP_KERNEL); | |
562 | if (!reader) | |
563 | return -ENOMEM; | |
564 | ||
565 | reader->log = log; | |
0441bcf4 NK |
566 | reader->r_ver = 1; |
567 | reader->r_all = in_egroup_p(inode->i_gid) || | |
568 | capable(CAP_SYSLOG); | |
569 | ||
355b0502 GKH |
570 | INIT_LIST_HEAD(&reader->list); |
571 | ||
572 | mutex_lock(&log->mutex); | |
573 | reader->r_off = log->head; | |
574 | list_add_tail(&reader->list, &log->readers); | |
575 | mutex_unlock(&log->mutex); | |
576 | ||
577 | file->private_data = reader; | |
578 | } else | |
579 | file->private_data = log; | |
580 | ||
581 | return 0; | |
582 | } | |
583 | ||
584 | /* | |
585 | * logger_release - the log's release file operation | |
586 | * | |
587 | * Note this is a total no-op in the write-only case. Keep it that way! | |
588 | */ | |
589 | static int logger_release(struct inode *ignored, struct file *file) | |
590 | { | |
591 | if (file->f_mode & FMODE_READ) { | |
592 | struct logger_reader *reader = file->private_data; | |
47de87a2 RV |
593 | struct logger_log *log = reader->log; |
594 | ||
595 | mutex_lock(&log->mutex); | |
355b0502 | 596 | list_del(&reader->list); |
47de87a2 RV |
597 | mutex_unlock(&log->mutex); |
598 | ||
355b0502 GKH |
599 | kfree(reader); |
600 | } | |
601 | ||
602 | return 0; | |
603 | } | |
604 | ||
605 | /* | |
606 | * logger_poll - the log's poll file operation, for poll/select/epoll | |
607 | * | |
608 | * Note we always return POLLOUT, because you can always write() to the log. | |
609 | * Note also that, strictly speaking, a return value of POLLIN does not | |
610 | * guarantee that the log is readable without blocking, as there is a small | |
611 | * chance that the writer can lap the reader in the interim between poll() | |
612 | * returning and the read() request. | |
613 | */ | |
614 | static unsigned int logger_poll(struct file *file, poll_table *wait) | |
615 | { | |
616 | struct logger_reader *reader; | |
617 | struct logger_log *log; | |
618 | unsigned int ret = POLLOUT | POLLWRNORM; | |
619 | ||
620 | if (!(file->f_mode & FMODE_READ)) | |
621 | return ret; | |
622 | ||
623 | reader = file->private_data; | |
624 | log = reader->log; | |
625 | ||
626 | poll_wait(file, &log->wq, wait); | |
627 | ||
628 | mutex_lock(&log->mutex); | |
0441bcf4 NK |
629 | if (!reader->r_all) |
630 | reader->r_off = get_next_entry_by_uid(log, | |
631 | reader->r_off, current_euid()); | |
632 | ||
355b0502 GKH |
633 | if (log->w_off != reader->r_off) |
634 | ret |= POLLIN | POLLRDNORM; | |
635 | mutex_unlock(&log->mutex); | |
636 | ||
637 | return ret; | |
638 | } | |
639 | ||
0441bcf4 NK |
640 | static long logger_set_version(struct logger_reader *reader, void __user *arg) |
641 | { | |
642 | int version; | |
643 | if (copy_from_user(&version, arg, sizeof(int))) | |
644 | return -EFAULT; | |
645 | ||
646 | if ((version < 1) || (version > 2)) | |
647 | return -EINVAL; | |
648 | ||
649 | reader->r_ver = version; | |
650 | return 0; | |
651 | } | |
652 | ||
355b0502 GKH |
653 | static long logger_ioctl(struct file *file, unsigned int cmd, unsigned long arg) |
654 | { | |
655 | struct logger_log *log = file_get_log(file); | |
656 | struct logger_reader *reader; | |
0441bcf4 NK |
657 | long ret = -EINVAL; |
658 | void __user *argp = (void __user *) arg; | |
355b0502 GKH |
659 | |
660 | mutex_lock(&log->mutex); | |
661 | ||
662 | switch (cmd) { | |
663 | case LOGGER_GET_LOG_BUF_SIZE: | |
664 | ret = log->size; | |
665 | break; | |
666 | case LOGGER_GET_LOG_LEN: | |
667 | if (!(file->f_mode & FMODE_READ)) { | |
668 | ret = -EBADF; | |
669 | break; | |
670 | } | |
671 | reader = file->private_data; | |
672 | if (log->w_off >= reader->r_off) | |
673 | ret = log->w_off - reader->r_off; | |
674 | else | |
675 | ret = (log->size - reader->r_off) + log->w_off; | |
676 | break; | |
677 | case LOGGER_GET_NEXT_ENTRY_LEN: | |
678 | if (!(file->f_mode & FMODE_READ)) { | |
679 | ret = -EBADF; | |
680 | break; | |
681 | } | |
682 | reader = file->private_data; | |
0441bcf4 NK |
683 | |
684 | if (!reader->r_all) | |
685 | reader->r_off = get_next_entry_by_uid(log, | |
686 | reader->r_off, current_euid()); | |
687 | ||
355b0502 | 688 | if (log->w_off != reader->r_off) |
0441bcf4 NK |
689 | ret = get_user_hdr_len(reader->r_ver) + |
690 | get_entry_msg_len(log, reader->r_off); | |
355b0502 GKH |
691 | else |
692 | ret = 0; | |
693 | break; | |
694 | case LOGGER_FLUSH_LOG: | |
695 | if (!(file->f_mode & FMODE_WRITE)) { | |
696 | ret = -EBADF; | |
697 | break; | |
698 | } | |
1e70bd46 CG |
699 | if (!(in_egroup_p(file->f_dentry->d_inode->i_gid) || |
700 | capable(CAP_SYSLOG))) { | |
701 | ret = -EPERM; | |
702 | break; | |
703 | } | |
355b0502 GKH |
704 | list_for_each_entry(reader, &log->readers, list) |
705 | reader->r_off = log->w_off; | |
706 | log->head = log->w_off; | |
707 | ret = 0; | |
708 | break; | |
0441bcf4 NK |
709 | case LOGGER_GET_VERSION: |
710 | if (!(file->f_mode & FMODE_READ)) { | |
711 | ret = -EBADF; | |
712 | break; | |
713 | } | |
714 | reader = file->private_data; | |
715 | ret = reader->r_ver; | |
716 | break; | |
717 | case LOGGER_SET_VERSION: | |
718 | if (!(file->f_mode & FMODE_READ)) { | |
719 | ret = -EBADF; | |
720 | break; | |
721 | } | |
722 | reader = file->private_data; | |
723 | ret = logger_set_version(reader, argp); | |
724 | break; | |
355b0502 GKH |
725 | } |
726 | ||
727 | mutex_unlock(&log->mutex); | |
728 | ||
729 | return ret; | |
730 | } | |
731 | ||
732 | static const struct file_operations logger_fops = { | |
733 | .owner = THIS_MODULE, | |
734 | .read = logger_read, | |
735 | .aio_write = logger_aio_write, | |
736 | .poll = logger_poll, | |
737 | .unlocked_ioctl = logger_ioctl, | |
738 | .compat_ioctl = logger_ioctl, | |
739 | .open = logger_open, | |
740 | .release = logger_release, | |
741 | }; | |
742 | ||
743 | /* | |
0441bcf4 NK |
744 | * Log size must must be a power of two, and greater than |
745 | * (LOGGER_ENTRY_MAX_PAYLOAD + sizeof(struct logger_entry)). | |
355b0502 | 746 | */ |
10b24199 TB |
747 | static int __init create_log(char *log_name, int size) |
748 | { | |
749 | int ret = 0; | |
750 | struct logger_log *log; | |
751 | unsigned char *buffer; | |
355b0502 | 752 | |
10b24199 TB |
753 | buffer = vmalloc(size); |
754 | if (buffer == NULL) | |
755 | return -ENOMEM; | |
355b0502 | 756 | |
10b24199 TB |
757 | log = kzalloc(sizeof(struct logger_log), GFP_KERNEL); |
758 | if (log == NULL) { | |
759 | ret = -ENOMEM; | |
760 | goto out_free_buffer; | |
761 | } | |
762 | log->buffer = buffer; | |
355b0502 | 763 | |
10b24199 TB |
764 | log->misc.minor = MISC_DYNAMIC_MINOR; |
765 | log->misc.name = kstrdup(log_name, GFP_KERNEL); | |
766 | if (log->misc.name == NULL) { | |
767 | ret = -ENOMEM; | |
768 | goto out_free_log; | |
769 | } | |
770 | ||
771 | log->misc.fops = &logger_fops; | |
772 | log->misc.parent = NULL; | |
355b0502 | 773 | |
10b24199 TB |
774 | init_waitqueue_head(&log->wq); |
775 | INIT_LIST_HEAD(&log->readers); | |
776 | mutex_init(&log->mutex); | |
777 | log->w_off = 0; | |
778 | log->head = 0; | |
779 | log->size = size; | |
780 | ||
781 | INIT_LIST_HEAD(&log->logs); | |
782 | list_add_tail(&log->logs, &log_list); | |
783 | ||
784 | /* finally, initialize the misc device for this log */ | |
355b0502 GKH |
785 | ret = misc_register(&log->misc); |
786 | if (unlikely(ret)) { | |
c810a399 SK |
787 | pr_err("failed to register misc device for log '%s'!\n", |
788 | log->misc.name); | |
10b24199 | 789 | goto out_free_log; |
355b0502 GKH |
790 | } |
791 | ||
c810a399 SK |
792 | pr_info("created %luK log '%s'\n", |
793 | (unsigned long) log->size >> 10, log->misc.name); | |
355b0502 GKH |
794 | |
795 | return 0; | |
10b24199 TB |
796 | |
797 | out_free_log: | |
798 | kfree(log); | |
799 | ||
800 | out_free_buffer: | |
801 | vfree(buffer); | |
802 | return ret; | |
355b0502 GKH |
803 | } |
804 | ||
805 | static int __init logger_init(void) | |
806 | { | |
807 | int ret; | |
808 | ||
10b24199 | 809 | ret = create_log(LOGGER_LOG_MAIN, 256*1024); |
355b0502 GKH |
810 | if (unlikely(ret)) |
811 | goto out; | |
812 | ||
10b24199 | 813 | ret = create_log(LOGGER_LOG_EVENTS, 256*1024); |
355b0502 GKH |
814 | if (unlikely(ret)) |
815 | goto out; | |
816 | ||
10b24199 | 817 | ret = create_log(LOGGER_LOG_RADIO, 256*1024); |
355b0502 GKH |
818 | if (unlikely(ret)) |
819 | goto out; | |
820 | ||
10b24199 | 821 | ret = create_log(LOGGER_LOG_SYSTEM, 256*1024); |
3537cdaa SM |
822 | if (unlikely(ret)) |
823 | goto out; | |
824 | ||
355b0502 GKH |
825 | out: |
826 | return ret; | |
827 | } | |
a3b41b7a LC |
828 | |
829 | static void __exit logger_exit(void) | |
830 | { | |
831 | struct logger_log *current_log, *next_log; | |
832 | ||
833 | list_for_each_entry_safe(current_log, next_log, &log_list, logs) { | |
834 | /* we have to delete all the entry inside log_list */ | |
835 | misc_deregister(¤t_log->misc); | |
836 | vfree(current_log->buffer); | |
837 | kfree(current_log->misc.name); | |
838 | list_del(¤t_log->logs); | |
839 | kfree(current_log); | |
840 | } | |
841 | } | |
842 | ||
843 | ||
355b0502 | 844 | device_initcall(logger_init); |
a3b41b7a LC |
845 | module_exit(logger_exit); |
846 | ||
847 | MODULE_LICENSE("GPL"); | |
848 | MODULE_AUTHOR("Robert Love, <rlove@google.com>"); | |
849 | MODULE_DESCRIPTION("Android Logger"); |