subr_log.c revision 1.69 
1/*	$OpenBSD: subr_log.c,v 1.69 2020/10/25 10:55:42 visa 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 */
77struct 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
85int	log_open;			/* also used in log() */
86int	msgbufmapped;			/* is the message buffer mapped */
87struct	msgbuf *msgbufp;		/* the mapped buffer, itself. */
88struct	msgbuf *consbufp;		/* console message buffer. */
89struct	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 */
96struct	mutex log_mtx =
97    MUTEX_INITIALIZER_FLAGS(IPL_HIGH, "logmtx", MTX_NOWITNESS);
98
99void filt_logrdetach(struct knote *kn);
100int filt_logread(struct knote *kn, long hint);
101
102const 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
109int dosendsyslog(struct proc *, const char *, size_t, int, enum uio_seg);
110void logtick(void *);
111size_t msgbuf_getlen(struct msgbuf *);
112
113void
114initmsgbuf(caddr_t buf, size_t bufsize)
115{
116	struct msgbuf *mbp;
117	long new_bufs;
118
119	/* Sanity-check the given size. */
120	if (bufsize < sizeof(struct msgbuf))
121		return;
122
123	mbp = msgbufp = (struct msgbuf *)buf;
124
125	new_bufs = bufsize - offsetof(struct msgbuf, msg_bufc);
126	if ((mbp->msg_magic != MSG_MAGIC) || (mbp->msg_bufs != new_bufs) ||
127	    (mbp->msg_bufr < 0) || (mbp->msg_bufr >= mbp->msg_bufs) ||
128	    (mbp->msg_bufx < 0) || (mbp->msg_bufx >= mbp->msg_bufs)) {
129		/*
130		 * If the buffer magic number is wrong, has changed
131		 * size (which shouldn't happen often), or is
132		 * internally inconsistent, initialize it.
133		 */
134
135		memset(buf, 0, bufsize);
136		mbp->msg_magic = MSG_MAGIC;
137		mbp->msg_bufs = new_bufs;
138	}
139
140	/* Always start new buffer data on a new line. */
141	if (mbp->msg_bufx > 0 && mbp->msg_bufc[mbp->msg_bufx - 1] != '\n')
142		msgbuf_putchar(msgbufp, '\n');
143
144	/* mark it as ready for use. */
145	msgbufmapped = 1;
146}
147
148void
149initconsbuf(void)
150{
151	/* Set up a buffer to collect /dev/console output */
152	consbufp = malloc(CONSBUFSIZE, M_TTYS, M_WAITOK | M_ZERO);
153	consbufp->msg_magic = MSG_MAGIC;
154	consbufp->msg_bufs = CONSBUFSIZE - offsetof(struct msgbuf, msg_bufc);
155}
156
157void
158msgbuf_putchar(struct msgbuf *mbp, const char c)
159{
160	if (mbp->msg_magic != MSG_MAGIC)
161		/* Nothing we can do */
162		return;
163
164	mtx_enter(&log_mtx);
165	mbp->msg_bufc[mbp->msg_bufx++] = c;
166	if (mbp->msg_bufx < 0 || mbp->msg_bufx >= mbp->msg_bufs)
167		mbp->msg_bufx = 0;
168	/* If the buffer is full, keep the most recent data. */
169	if (mbp->msg_bufr == mbp->msg_bufx) {
170		if (++mbp->msg_bufr >= mbp->msg_bufs)
171			mbp->msg_bufr = 0;
172		mbp->msg_bufd++;
173	}
174	mtx_leave(&log_mtx);
175}
176
177size_t
178msgbuf_getlen(struct msgbuf *mbp)
179{
180	long len;
181
182	mtx_enter(&log_mtx);
183	len = mbp->msg_bufx - mbp->msg_bufr;
184	if (len < 0)
185		len += mbp->msg_bufs;
186	mtx_leave(&log_mtx);
187	return (len);
188}
189
190int
191logopen(dev_t dev, int flags, int mode, struct proc *p)
192{
193	if (log_open)
194		return (EBUSY);
195	log_open = 1;
196	sigio_init(&logsoftc.sc_sigio);
197	timeout_set(&logsoftc.sc_tick, logtick, NULL);
198	timeout_add_msec(&logsoftc.sc_tick, LOG_TICK);
199	return (0);
200}
201
202int
203logclose(dev_t dev, int flag, int mode, struct proc *p)
204{
205	struct file *fp;
206
207	fp = syslogf;
208	syslogf = NULL;
209	if (fp)
210		FRELE(fp, p);
211	log_open = 0;
212	timeout_del(&logsoftc.sc_tick);
213	logsoftc.sc_state = 0;
214	sigio_free(&logsoftc.sc_sigio);
215	return (0);
216}
217
218int
219logread(dev_t dev, struct uio *uio, int flag)
220{
221	struct sleep_state sls;
222	struct msgbuf *mbp = msgbufp;
223	size_t l, rpos;
224	int error = 0;
225
226	mtx_enter(&log_mtx);
227	while (mbp->msg_bufr == mbp->msg_bufx) {
228		if (flag & IO_NDELAY) {
229			error = EWOULDBLOCK;
230			goto out;
231		}
232		logsoftc.sc_state |= LOG_RDWAIT;
233		mtx_leave(&log_mtx);
234		/*
235		 * Set up and enter sleep manually instead of using msleep()
236		 * to keep log_mtx as a leaf lock.
237		 */
238		sleep_setup(&sls, mbp, LOG_RDPRI | PCATCH, "klog");
239		sleep_setup_signal(&sls);
240		sleep_finish(&sls, logsoftc.sc_state & LOG_RDWAIT);
241		error = sleep_finish_signal(&sls);
242		mtx_enter(&log_mtx);
243		if (error)
244			goto out;
245	}
246
247	if (mbp->msg_bufd > 0) {
248		char buf[64];
249		long ndropped;
250
251		ndropped = mbp->msg_bufd;
252		mtx_leave(&log_mtx);
253		l = snprintf(buf, sizeof(buf),
254		    "<%d>klog: dropped %ld byte%s, message buffer full\n",
255		    LOG_KERN|LOG_WARNING, ndropped,
256		    ndropped == 1 ? "" : "s");
257		error = uiomove(buf, ulmin(l, sizeof(buf) - 1), uio);
258		mtx_enter(&log_mtx);
259		if (error)
260			goto out;
261		mbp->msg_bufd -= ndropped;
262	}
263
264	while (uio->uio_resid > 0) {
265		if (mbp->msg_bufx >= mbp->msg_bufr)
266			l = mbp->msg_bufx - mbp->msg_bufr;
267		else
268			l = mbp->msg_bufs - mbp->msg_bufr;
269		l = ulmin(l, uio->uio_resid);
270		if (l == 0)
271			break;
272		rpos = mbp->msg_bufr;
273		mtx_leave(&log_mtx);
274		/* Ignore that concurrent readers may consume the same data. */
275		error = uiomove(&mbp->msg_bufc[rpos], l, uio);
276		mtx_enter(&log_mtx);
277		if (error)
278			break;
279		mbp->msg_bufr += l;
280		if (mbp->msg_bufr < 0 || mbp->msg_bufr >= mbp->msg_bufs)
281			mbp->msg_bufr = 0;
282	}
283 out:
284	mtx_leave(&log_mtx);
285	return (error);
286}
287
288int
289logpoll(dev_t dev, int events, struct proc *p)
290{
291	int revents = 0;
292
293	mtx_enter(&log_mtx);
294	if (events & (POLLIN | POLLRDNORM)) {
295		if (msgbufp->msg_bufr != msgbufp->msg_bufx)
296			revents |= events & (POLLIN | POLLRDNORM);
297		else
298			selrecord(p, &logsoftc.sc_selp);
299	}
300	mtx_leave(&log_mtx);
301	return (revents);
302}
303
304int
305logkqfilter(dev_t dev, struct knote *kn)
306{
307	struct klist *klist;
308	int s;
309
310	switch (kn->kn_filter) {
311	case EVFILT_READ:
312		klist = &logsoftc.sc_selp.si_note;
313		kn->kn_fop = &logread_filtops;
314		break;
315	default:
316		return (EINVAL);
317	}
318
319	kn->kn_hook = (void *)msgbufp;
320
321	s = splhigh();
322	klist_insert(klist, kn);
323	splx(s);
324
325	return (0);
326}
327
328void
329filt_logrdetach(struct knote *kn)
330{
331	int s;
332
333	s = splhigh();
334	klist_remove(&logsoftc.sc_selp.si_note, kn);
335	splx(s);
336}
337
338int
339filt_logread(struct knote *kn, long hint)
340{
341	struct msgbuf *mbp = kn->kn_hook;
342
343	kn->kn_data = msgbuf_getlen(mbp);
344	return (kn->kn_data != 0);
345}
346
347void
348logwakeup(void)
349{
350	/*
351	 * The actual wakeup has to be deferred because logwakeup() can be
352	 * called in very varied contexts.
353	 * Keep the print routines usable in as many situations as possible
354	 * by not using locking here.
355	 */
356
357	/*
358	 * Ensure that preceding stores become visible to other CPUs
359	 * before the flag.
360	 */
361	membar_producer();
362
363	logsoftc.sc_need_wakeup = 1;
364}
365
366void
367logtick(void *arg)
368{
369	int state;
370
371	if (!log_open)
372		return;
373
374	if (!logsoftc.sc_need_wakeup)
375		goto out;
376	logsoftc.sc_need_wakeup = 0;
377
378	/*
379	 * sc_need_wakeup has to be cleared before handling the wakeup.
380	 * Visiting log_mtx ensures the proper order.
381	 */
382
383	mtx_enter(&log_mtx);
384	state = logsoftc.sc_state;
385	if (logsoftc.sc_state & LOG_RDWAIT)
386		logsoftc.sc_state &= ~LOG_RDWAIT;
387	mtx_leave(&log_mtx);
388
389	selwakeup(&logsoftc.sc_selp);
390	if (state & LOG_ASYNC)
391		pgsigio(&logsoftc.sc_sigio, SIGIO, 0);
392	if (state & LOG_RDWAIT)
393		wakeup(msgbufp);
394out:
395	timeout_add_msec(&logsoftc.sc_tick, LOG_TICK);
396}
397
398int
399logioctl(dev_t dev, u_long com, caddr_t data, int flag, struct proc *p)
400{
401	struct file *fp;
402	int error;
403
404	switch (com) {
405
406	/* return number of characters immediately available */
407	case FIONREAD:
408		*(int *)data = (int)msgbuf_getlen(msgbufp);
409		break;
410
411	case FIONBIO:
412		break;
413
414	case FIOASYNC:
415		mtx_enter(&log_mtx);
416		if (*(int *)data)
417			logsoftc.sc_state |= LOG_ASYNC;
418		else
419			logsoftc.sc_state &= ~LOG_ASYNC;
420		mtx_leave(&log_mtx);
421		break;
422
423	case FIOSETOWN:
424	case TIOCSPGRP:
425		return (sigio_setown(&logsoftc.sc_sigio, com, data));
426
427	case FIOGETOWN:
428	case TIOCGPGRP:
429		sigio_getown(&logsoftc.sc_sigio, com, data);
430		break;
431
432	case LIOCSFD:
433		if ((error = suser(p)) != 0)
434			return (error);
435		fp = syslogf;
436		if ((error = getsock(p, *(int *)data, &syslogf)) != 0)
437			return (error);
438		if (fp)
439			FRELE(fp, p);
440		break;
441
442	default:
443		return (ENOTTY);
444	}
445	return (0);
446}
447
448int
449sys_sendsyslog(struct proc *p, void *v, register_t *retval)
450{
451	struct sys_sendsyslog_args /* {
452		syscallarg(const char *) buf;
453		syscallarg(size_t) nbyte;
454		syscallarg(int) flags;
455	} */ *uap = v;
456	int error;
457	static int dropped_count, orig_error, orig_pid;
458
459	if (dropped_count) {
460		size_t l;
461		char buf[80];
462
463		l = snprintf(buf, sizeof(buf),
464		    "<%d>sendsyslog: dropped %d message%s, error %d, pid %d",
465		    LOG_KERN|LOG_WARNING, dropped_count,
466		    dropped_count == 1 ? "" : "s", orig_error, orig_pid);
467		error = dosendsyslog(p, buf, ulmin(l, sizeof(buf) - 1),
468		    0, UIO_SYSSPACE);
469		if (error == 0) {
470			dropped_count = 0;
471			orig_error = 0;
472			orig_pid = 0;
473		}
474	}
475	error = dosendsyslog(p, SCARG(uap, buf), SCARG(uap, nbyte),
476	    SCARG(uap, flags), UIO_USERSPACE);
477	if (error) {
478		dropped_count++;
479		orig_error = error;
480		orig_pid = p->p_p->ps_pid;
481	}
482	return (error);
483}
484
485int
486dosendsyslog(struct proc *p, const char *buf, size_t nbyte, int flags,
487    enum uio_seg sflg)
488{
489#ifdef KTRACE
490	struct iovec ktriov;
491#endif
492	struct file *fp;
493	char pri[6], *kbuf;
494	struct iovec aiov;
495	struct uio auio;
496	size_t i, len;
497	int error;
498
499	if (nbyte > LOG_MAXLINE)
500		nbyte = LOG_MAXLINE;
501
502	/* Global variable syslogf may change during sleep, use local copy. */
503	fp = syslogf;
504	if (fp)
505		FREF(fp);
506	else if (!ISSET(flags, LOG_CONS))
507		return (ENOTCONN);
508	else {
509		/*
510		 * Strip off syslog priority when logging to console.
511		 * LOG_PRIMASK | LOG_FACMASK is 0x03ff, so at most 4
512		 * decimal digits may appear in priority as <1023>.
513		 */
514		len = MIN(nbyte, sizeof(pri));
515		if (sflg == UIO_USERSPACE) {
516			if ((error = copyin(buf, pri, len)))
517				return (error);
518		} else
519			memcpy(pri, buf, len);
520		if (0 < len && pri[0] == '<') {
521			for (i = 1; i < len; i++) {
522				if (pri[i] < '0' || pri[i] > '9')
523					break;
524			}
525			if (i < len && pri[i] == '>') {
526				i++;
527				/* There must be at least one digit <0>. */
528				if (i >= 3) {
529					buf += i;
530					nbyte -= i;
531				}
532			}
533		}
534	}
535
536	aiov.iov_base = (char *)buf;
537	aiov.iov_len = nbyte;
538	auio.uio_iov = &aiov;
539	auio.uio_iovcnt = 1;
540	auio.uio_segflg = sflg;
541	auio.uio_rw = UIO_WRITE;
542	auio.uio_procp = p;
543	auio.uio_offset = 0;
544	auio.uio_resid = aiov.iov_len;
545#ifdef KTRACE
546	if (sflg == UIO_USERSPACE && KTRPOINT(p, KTR_GENIO))
547		ktriov = aiov;
548	else
549		ktriov.iov_len = 0;
550#endif
551
552	len = auio.uio_resid;
553	if (fp) {
554		int flags = (fp->f_flag & FNONBLOCK) ? MSG_DONTWAIT : 0;
555		error = sosend(fp->f_data, NULL, &auio, NULL, NULL, flags);
556		if (error == 0)
557			len -= auio.uio_resid;
558	} else if (constty || cn_devvp) {
559		error = cnwrite(0, &auio, 0);
560		if (error == 0)
561			len -= auio.uio_resid;
562		aiov.iov_base = "\r\n";
563		aiov.iov_len = 2;
564		auio.uio_iov = &aiov;
565		auio.uio_iovcnt = 1;
566		auio.uio_segflg = UIO_SYSSPACE;
567		auio.uio_rw = UIO_WRITE;
568		auio.uio_procp = p;
569		auio.uio_offset = 0;
570		auio.uio_resid = aiov.iov_len;
571		cnwrite(0, &auio, 0);
572	} else {
573		/* XXX console redirection breaks down... */
574		if (sflg == UIO_USERSPACE) {
575			kbuf = malloc(len, M_TEMP, M_WAITOK);
576			error = copyin(aiov.iov_base, kbuf, len);
577		} else {
578			kbuf = aiov.iov_base;
579			error = 0;
580		}
581		if (error == 0)
582			for (i = 0; i < len; i++) {
583				if (kbuf[i] == '\0')
584					break;
585				cnputc(kbuf[i]);
586				auio.uio_resid--;
587			}
588		if (sflg == UIO_USERSPACE)
589			free(kbuf, M_TEMP, len);
590		if (error == 0)
591			len -= auio.uio_resid;
592		cnputc('\n');
593	}
594
595#ifdef KTRACE
596	if (error == 0 && ktriov.iov_len != 0)
597		ktrgenio(p, -1, UIO_WRITE, &ktriov, len);
598#endif
599	if (fp)
600		FRELE(fp, p);
601	else
602		error = ENOTCONN;
603	return (error);
604}
605