xref: /openbsd/sys/kern/subr_log.c (revision 55cc5ba3) 
1 /*	$OpenBSD: subr_log.c,v 1.72 2021/02/08 08:18:45 mpi Exp $	*/
2 /*	$NetBSD: subr_log.c,v 1.11 1996/03/30 22:24:44 christos Exp $	*/
3 
4 /*
5  * Copyright (c) 1982, 1986, 1993
6  *	The Regents of the University of California.  All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. Neither the name of the University nor the names of its contributors
17  *    may be used to endorse or promote products derived from this software
18  *    without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  *
32  *	@(#)subr_log.c	8.1 (Berkeley) 6/10/93
33  */
34 
35 /*
36  * Error log buffer for kernel printf's.
37  */
38 
39 #include <sys/param.h>
40 #include <sys/systm.h>
41 #include <sys/proc.h>
42 #include <sys/vnode.h>
43 #include <sys/ioctl.h>
44 #include <sys/msgbuf.h>
45 #include <sys/file.h>
46 #include <sys/tty.h>
47 #include <sys/signalvar.h>
48 #include <sys/syslog.h>
49 #include <sys/poll.h>
50 #include <sys/malloc.h>
51 #include <sys/filedesc.h>
52 #include <sys/socket.h>
53 #include <sys/socketvar.h>
54 #include <sys/fcntl.h>
55 #include <sys/mutex.h>
56 #include <sys/timeout.h>
57 
58 #ifdef KTRACE
59 #include <sys/ktrace.h>
60 #endif
61 
62 #include <sys/mount.h>
63 #include <sys/syscallargs.h>
64 
65 #include <dev/cons.h>
66 
67 #define LOG_RDPRI	(PZERO + 1)
68 #define LOG_TICK	50		/* log tick interval in msec */
69 
70 #define LOG_ASYNC	0x04
71 #define LOG_RDWAIT	0x08
72 
73 /*
74  * Locking:
75  *	L	log_mtx
76  */
77 struct logsoftc {
78 	int	sc_state;		/* [L] see above for possibilities */
79 	struct	selinfo sc_selp;	/* process waiting on select call */
80 	struct	sigio_ref sc_sigio;	/* async I/O registration */
81 	int	sc_need_wakeup;		/* if set, wake up waiters */
82 	struct timeout sc_tick;		/* wakeup poll timeout */
83 } logsoftc;
84 
85 int	log_open;			/* also used in log() */
86 int	msgbufmapped;			/* is the message buffer mapped */
87 struct	msgbuf *msgbufp;		/* the mapped buffer, itself. */
88 struct	msgbuf *consbufp;		/* console message buffer. */
89 struct	file *syslogf;
90 
91 /*
92  * Lock that serializes access to log message buffers.
93  * This should be kept as a leaf lock in order not to constrain where
94  * printf(9) can be used.
95  */
96 struct	mutex log_mtx =
97     MUTEX_INITIALIZER_FLAGS(IPL_HIGH, "logmtx", MTX_NOWITNESS);
98 
99 void filt_logrdetach(struct knote *kn);
100 int filt_logread(struct knote *kn, long hint);
101 
102 const struct filterops logread_filtops = {
103 	.f_flags	= FILTEROP_ISFD,
104 	.f_attach	= NULL,
105 	.f_detach	= filt_logrdetach,
106 	.f_event	= filt_logread,
107 };
108 
109 int dosendsyslog(struct proc *, const char *, size_t, int, enum uio_seg);
110 void logtick(void *);
111 size_t msgbuf_getlen(struct msgbuf *);
112 void msgbuf_putchar_locked(struct msgbuf *, const char);
113 
114 void
115 initmsgbuf(caddr_t buf, size_t bufsize)
116 {
117 	struct msgbuf *mbp;
118 	long new_bufs;
119 
120 	/* Sanity-check the given size. */
121 	if (bufsize < sizeof(struct msgbuf))
122 		return;
123 
124 	mbp = msgbufp = (struct msgbuf *)buf;
125 
126 	new_bufs = bufsize - offsetof(struct msgbuf, msg_bufc);
127 	if ((mbp->msg_magic != MSG_MAGIC) || (mbp->msg_bufs != new_bufs) ||
128 	    (mbp->msg_bufr < 0) || (mbp->msg_bufr >= mbp->msg_bufs) ||
129 	    (mbp->msg_bufx < 0) || (mbp->msg_bufx >= mbp->msg_bufs)) {
130 		/*
131 		 * If the buffer magic number is wrong, has changed
132 		 * size (which shouldn't happen often), or is
133 		 * internally inconsistent, initialize it.
134 		 */
135 
136 		memset(buf, 0, bufsize);
137 		mbp->msg_magic = MSG_MAGIC;
138 		mbp->msg_bufs = new_bufs;
139 	}
140 
141 	/*
142 	 * Always start new buffer data on a new line.
143 	 * Avoid using log_mtx because mutexes do not work during early boot
144 	 * on some architectures.
145 	 */
146 	if (mbp->msg_bufx > 0 && mbp->msg_bufc[mbp->msg_bufx - 1] != '\n')
147 		msgbuf_putchar_locked(mbp, '\n');
148 
149 	/* mark it as ready for use. */
150 	msgbufmapped = 1;
151 }
152 
153 void
154 initconsbuf(void)
155 {
156 	/* Set up a buffer to collect /dev/console output */
157 	consbufp = malloc(CONSBUFSIZE, M_TTYS, M_WAITOK | M_ZERO);
158 	consbufp->msg_magic = MSG_MAGIC;
159 	consbufp->msg_bufs = CONSBUFSIZE - offsetof(struct msgbuf, msg_bufc);
160 }
161 
162 void
163 msgbuf_putchar(struct msgbuf *mbp, const char c)
164 {
165 	if (mbp->msg_magic != MSG_MAGIC)
166 		/* Nothing we can do */
167 		return;
168 
169 	mtx_enter(&log_mtx);
170 	msgbuf_putchar_locked(mbp, c);
171 	mtx_leave(&log_mtx);
172 }
173 
174 void
175 msgbuf_putchar_locked(struct msgbuf *mbp, const char c)
176 {
177 	mbp->msg_bufc[mbp->msg_bufx++] = c;
178 	if (mbp->msg_bufx < 0 || mbp->msg_bufx >= mbp->msg_bufs)
179 		mbp->msg_bufx = 0;
180 	/* If the buffer is full, keep the most recent data. */
181 	if (mbp->msg_bufr == mbp->msg_bufx) {
182 		if (++mbp->msg_bufr >= mbp->msg_bufs)
183 			mbp->msg_bufr = 0;
184 		mbp->msg_bufd++;
185 	}
186 }
187 
188 size_t
189 msgbuf_getlen(struct msgbuf *mbp)
190 {
191 	long len;
192 
193 	mtx_enter(&log_mtx);
194 	len = mbp->msg_bufx - mbp->msg_bufr;
195 	if (len < 0)
196 		len += mbp->msg_bufs;
197 	mtx_leave(&log_mtx);
198 	return (len);
199 }
200 
201 int
202 logopen(dev_t dev, int flags, int mode, struct proc *p)
203 {
204 	if (log_open)
205 		return (EBUSY);
206 	log_open = 1;
207 	sigio_init(&logsoftc.sc_sigio);
208 	timeout_set(&logsoftc.sc_tick, logtick, NULL);
209 	timeout_add_msec(&logsoftc.sc_tick, LOG_TICK);
210 	return (0);
211 }
212 
213 int
214 logclose(dev_t dev, int flag, int mode, struct proc *p)
215 {
216 	struct file *fp;
217 
218 	fp = syslogf;
219 	syslogf = NULL;
220 	if (fp)
221 		FRELE(fp, p);
222 	log_open = 0;
223 	timeout_del(&logsoftc.sc_tick);
224 	logsoftc.sc_state = 0;
225 	sigio_free(&logsoftc.sc_sigio);
226 	return (0);
227 }
228 
229 int
230 logread(dev_t dev, struct uio *uio, int flag)
231 {
232 	struct sleep_state sls;
233 	struct msgbuf *mbp = msgbufp;
234 	size_t l, rpos;
235 	int error = 0;
236 
237 	mtx_enter(&log_mtx);
238 	while (mbp->msg_bufr == mbp->msg_bufx) {
239 		if (flag & IO_NDELAY) {
240 			error = EWOULDBLOCK;
241 			goto out;
242 		}
243 		logsoftc.sc_state |= LOG_RDWAIT;
244 		mtx_leave(&log_mtx);
245 		/*
246 		 * Set up and enter sleep manually instead of using msleep()
247 		 * to keep log_mtx as a leaf lock.
248 		 */
249 		sleep_setup(&sls, mbp, LOG_RDPRI | PCATCH, "klog", 0);
250 		error = sleep_finish(&sls, logsoftc.sc_state & LOG_RDWAIT);
251 		mtx_enter(&log_mtx);
252 		if (error)
253 			goto out;
254 	}
255 
256 	if (mbp->msg_bufd > 0) {
257 		char buf[64];
258 		long ndropped;
259 
260 		ndropped = mbp->msg_bufd;
261 		mtx_leave(&log_mtx);
262 		l = snprintf(buf, sizeof(buf),
263 		    "<%d>klog: dropped %ld byte%s, message buffer full\n",
264 		    LOG_KERN|LOG_WARNING, ndropped,
265 		    ndropped == 1 ? "" : "s");
266 		error = uiomove(buf, ulmin(l, sizeof(buf) - 1), uio);
267 		mtx_enter(&log_mtx);
268 		if (error)
269 			goto out;
270 		mbp->msg_bufd -= ndropped;
271 	}
272 
273 	while (uio->uio_resid > 0) {
274 		if (mbp->msg_bufx >= mbp->msg_bufr)
275 			l = mbp->msg_bufx - mbp->msg_bufr;
276 		else
277 			l = mbp->msg_bufs - mbp->msg_bufr;
278 		l = ulmin(l, uio->uio_resid);
279 		if (l == 0)
280 			break;
281 		rpos = mbp->msg_bufr;
282 		mtx_leave(&log_mtx);
283 		/* Ignore that concurrent readers may consume the same data. */
284 		error = uiomove(&mbp->msg_bufc[rpos], l, uio);
285 		mtx_enter(&log_mtx);
286 		if (error)
287 			break;
288 		mbp->msg_bufr += l;
289 		if (mbp->msg_bufr < 0 || mbp->msg_bufr >= mbp->msg_bufs)
290 			mbp->msg_bufr = 0;
291 	}
292  out:
293 	mtx_leave(&log_mtx);
294 	return (error);
295 }
296 
297 int
298 logpoll(dev_t dev, int events, struct proc *p)
299 {
300 	int revents = 0;
301 
302 	mtx_enter(&log_mtx);
303 	if (events & (POLLIN | POLLRDNORM)) {
304 		if (msgbufp->msg_bufr != msgbufp->msg_bufx)
305 			revents |= events & (POLLIN | POLLRDNORM);
306 		else
307 			selrecord(p, &logsoftc.sc_selp);
308 	}
309 	mtx_leave(&log_mtx);
310 	return (revents);
311 }
312 
313 int
314 logkqfilter(dev_t dev, struct knote *kn)
315 {
316 	struct klist *klist;
317 	int s;
318 
319 	switch (kn->kn_filter) {
320 	case EVFILT_READ:
321 		klist = &logsoftc.sc_selp.si_note;
322 		kn->kn_fop = &logread_filtops;
323 		break;
324 	default:
325 		return (EINVAL);
326 	}
327 
328 	kn->kn_hook = (void *)msgbufp;
329 
330 	s = splhigh();
331 	klist_insert_locked(klist, kn);
332 	splx(s);
333 
334 	return (0);
335 }
336 
337 void
338 filt_logrdetach(struct knote *kn)
339 {
340 	int s;
341 
342 	s = splhigh();
343 	klist_remove_locked(&logsoftc.sc_selp.si_note, kn);
344 	splx(s);
345 }
346 
347 int
348 filt_logread(struct knote *kn, long hint)
349 {
350 	struct msgbuf *mbp = kn->kn_hook;
351 
352 	kn->kn_data = msgbuf_getlen(mbp);
353 	return (kn->kn_data != 0);
354 }
355 
356 void
357 logwakeup(void)
358 {
359 	/*
360 	 * The actual wakeup has to be deferred because logwakeup() can be
361 	 * called in very varied contexts.
362 	 * Keep the print routines usable in as many situations as possible
363 	 * by not using locking here.
364 	 */
365 
366 	/*
367 	 * Ensure that preceding stores become visible to other CPUs
368 	 * before the flag.
369 	 */
370 	membar_producer();
371 
372 	logsoftc.sc_need_wakeup = 1;
373 }
374 
375 void
376 logtick(void *arg)
377 {
378 	int state;
379 
380 	if (!log_open)
381 		return;
382 
383 	if (!logsoftc.sc_need_wakeup)
384 		goto out;
385 	logsoftc.sc_need_wakeup = 0;
386 
387 	/*
388 	 * sc_need_wakeup has to be cleared before handling the wakeup.
389 	 * Visiting log_mtx ensures the proper order.
390 	 */
391 
392 	mtx_enter(&log_mtx);
393 	state = logsoftc.sc_state;
394 	if (logsoftc.sc_state & LOG_RDWAIT)
395 		logsoftc.sc_state &= ~LOG_RDWAIT;
396 	mtx_leave(&log_mtx);
397 
398 	selwakeup(&logsoftc.sc_selp);
399 	if (state & LOG_ASYNC)
400 		pgsigio(&logsoftc.sc_sigio, SIGIO, 0);
401 	if (state & LOG_RDWAIT)
402 		wakeup(msgbufp);
403 out:
404 	timeout_add_msec(&logsoftc.sc_tick, LOG_TICK);
405 }
406 
407 int
408 logioctl(dev_t dev, u_long com, caddr_t data, int flag, struct proc *p)
409 {
410 	struct file *fp;
411 	int error;
412 
413 	switch (com) {
414 
415 	/* return number of characters immediately available */
416 	case FIONREAD:
417 		*(int *)data = (int)msgbuf_getlen(msgbufp);
418 		break;
419 
420 	case FIONBIO:
421 		break;
422 
423 	case FIOASYNC:
424 		mtx_enter(&log_mtx);
425 		if (*(int *)data)
426 			logsoftc.sc_state |= LOG_ASYNC;
427 		else
428 			logsoftc.sc_state &= ~LOG_ASYNC;
429 		mtx_leave(&log_mtx);
430 		break;
431 
432 	case FIOSETOWN:
433 	case TIOCSPGRP:
434 		return (sigio_setown(&logsoftc.sc_sigio, com, data));
435 
436 	case FIOGETOWN:
437 	case TIOCGPGRP:
438 		sigio_getown(&logsoftc.sc_sigio, com, data);
439 		break;
440 
441 	case LIOCSFD:
442 		if ((error = suser(p)) != 0)
443 			return (error);
444 		fp = syslogf;
445 		if ((error = getsock(p, *(int *)data, &syslogf)) != 0)
446 			return (error);
447 		if (fp)
448 			FRELE(fp, p);
449 		break;
450 
451 	default:
452 		return (ENOTTY);
453 	}
454 	return (0);
455 }
456 
457 int
458 sys_sendsyslog(struct proc *p, void *v, register_t *retval)
459 {
460 	struct sys_sendsyslog_args /* {
461 		syscallarg(const char *) buf;
462 		syscallarg(size_t) nbyte;
463 		syscallarg(int) flags;
464 	} */ *uap = v;
465 	int error;
466 	static int dropped_count, orig_error, orig_pid;
467 
468 	if (dropped_count) {
469 		size_t l;
470 		char buf[80];
471 
472 		l = snprintf(buf, sizeof(buf),
473 		    "<%d>sendsyslog: dropped %d message%s, error %d, pid %d",
474 		    LOG_KERN|LOG_WARNING, dropped_count,
475 		    dropped_count == 1 ? "" : "s", orig_error, orig_pid);
476 		error = dosendsyslog(p, buf, ulmin(l, sizeof(buf) - 1),
477 		    0, UIO_SYSSPACE);
478 		if (error == 0) {
479 			dropped_count = 0;
480 			orig_error = 0;
481 			orig_pid = 0;
482 		}
483 	}
484 	error = dosendsyslog(p, SCARG(uap, buf), SCARG(uap, nbyte),
485 	    SCARG(uap, flags), UIO_USERSPACE);
486 	if (error) {
487 		dropped_count++;
488 		orig_error = error;
489 		orig_pid = p->p_p->ps_pid;
490 	}
491 	return (error);
492 }
493 
494 int
495 dosendsyslog(struct proc *p, const char *buf, size_t nbyte, int flags,
496     enum uio_seg sflg)
497 {
498 #ifdef KTRACE
499 	struct iovec ktriov;
500 #endif
501 	struct file *fp;
502 	char pri[6], *kbuf;
503 	struct iovec aiov;
504 	struct uio auio;
505 	size_t i, len;
506 	int error;
507 
508 	if (nbyte > LOG_MAXLINE)
509 		nbyte = LOG_MAXLINE;
510 
511 	/* Global variable syslogf may change during sleep, use local copy. */
512 	fp = syslogf;
513 	if (fp)
514 		FREF(fp);
515 	else if (!ISSET(flags, LOG_CONS))
516 		return (ENOTCONN);
517 	else {
518 		/*
519 		 * Strip off syslog priority when logging to console.
520 		 * LOG_PRIMASK | LOG_FACMASK is 0x03ff, so at most 4
521 		 * decimal digits may appear in priority as <1023>.
522 		 */
523 		len = MIN(nbyte, sizeof(pri));
524 		if (sflg == UIO_USERSPACE) {
525 			if ((error = copyin(buf, pri, len)))
526 				return (error);
527 		} else
528 			memcpy(pri, buf, len);
529 		if (0 < len && pri[0] == '<') {
530 			for (i = 1; i < len; i++) {
531 				if (pri[i] < '0' || pri[i] > '9')
532 					break;
533 			}
534 			if (i < len && pri[i] == '>') {
535 				i++;
536 				/* There must be at least one digit <0>. */
537 				if (i >= 3) {
538 					buf += i;
539 					nbyte -= i;
540 				}
541 			}
542 		}
543 	}
544 
545 	aiov.iov_base = (char *)buf;
546 	aiov.iov_len = nbyte;
547 	auio.uio_iov = &aiov;
548 	auio.uio_iovcnt = 1;
549 	auio.uio_segflg = sflg;
550 	auio.uio_rw = UIO_WRITE;
551 	auio.uio_procp = p;
552 	auio.uio_offset = 0;
553 	auio.uio_resid = aiov.iov_len;
554 #ifdef KTRACE
555 	if (sflg == UIO_USERSPACE && KTRPOINT(p, KTR_GENIO))
556 		ktriov = aiov;
557 	else
558 		ktriov.iov_len = 0;
559 #endif
560 
561 	len = auio.uio_resid;
562 	if (fp) {
563 		int flags = (fp->f_flag & FNONBLOCK) ? MSG_DONTWAIT : 0;
564 		error = sosend(fp->f_data, NULL, &auio, NULL, NULL, flags);
565 		if (error == 0)
566 			len -= auio.uio_resid;
567 	} else if (constty || cn_devvp) {
568 		error = cnwrite(0, &auio, 0);
569 		if (error == 0)
570 			len -= auio.uio_resid;
571 		aiov.iov_base = "\r\n";
572 		aiov.iov_len = 2;
573 		auio.uio_iov = &aiov;
574 		auio.uio_iovcnt = 1;
575 		auio.uio_segflg = UIO_SYSSPACE;
576 		auio.uio_rw = UIO_WRITE;
577 		auio.uio_procp = p;
578 		auio.uio_offset = 0;
579 		auio.uio_resid = aiov.iov_len;
580 		cnwrite(0, &auio, 0);
581 	} else {
582 		/* XXX console redirection breaks down... */
583 		if (sflg == UIO_USERSPACE) {
584 			kbuf = malloc(len, M_TEMP, M_WAITOK);
585 			error = copyin(aiov.iov_base, kbuf, len);
586 		} else {
587 			kbuf = aiov.iov_base;
588 			error = 0;
589 		}
590 		if (error == 0)
591 			for (i = 0; i < len; i++) {
592 				if (kbuf[i] == '\0')
593 					break;
594 				cnputc(kbuf[i]);
595 				auio.uio_resid--;
596 			}
597 		if (sflg == UIO_USERSPACE)
598 			free(kbuf, M_TEMP, len);
599 		if (error == 0)
600 			len -= auio.uio_resid;
601 		cnputc('\n');
602 	}
603 
604 #ifdef KTRACE
605 	if (error == 0 && ktriov.iov_len != 0)
606 		ktrgenio(p, -1, UIO_WRITE, &ktriov, len);
607 #endif
608 	if (fp)
609 		FRELE(fp, p);
610 	else
611 		error = ENOTCONN;
612 	return (error);
613 }
614