subr_log.c revision 1.60 
1/*	$OpenBSD: subr_log.c,v 1.60 2019/12/24 12:56:07 bluhm 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/timeout.h>
56
57#ifdef KTRACE
58#include <sys/ktrace.h>
59#endif
60
61#include <sys/mount.h>
62#include <sys/syscallargs.h>
63
64#include <dev/cons.h>
65
66#define LOG_RDPRI	(PZERO + 1)
67#define LOG_TICK	50		/* log tick interval in msec */
68
69#define LOG_ASYNC	0x04
70#define LOG_RDWAIT	0x08
71
72struct logsoftc {
73	int	sc_state;		/* see above for possibilities */
74	struct	selinfo sc_selp;	/* process waiting on select call */
75	int	sc_pgid;		/* process/group for async I/O */
76	uid_t	sc_siguid;		/* uid for process that set sc_pgid */
77	uid_t	sc_sigeuid;		/* euid for process that set sc_pgid */
78	int	sc_need_wakeup;		/* if set, wake up waiters */
79	struct timeout sc_tick;		/* wakeup poll timeout */
80} logsoftc;
81
82int	log_open;			/* also used in log() */
83int	msgbufmapped;			/* is the message buffer mapped */
84struct	msgbuf *msgbufp;		/* the mapped buffer, itself. */
85struct	msgbuf *consbufp;		/* console message buffer. */
86struct	file *syslogf;
87
88void filt_logrdetach(struct knote *kn);
89int filt_logread(struct knote *kn, long hint);
90
91struct filterops logread_filtops =
92	{ 1, NULL, filt_logrdetach, filt_logread};
93
94int dosendsyslog(struct proc *, const char *, size_t, int, enum uio_seg);
95void logtick(void *);
96
97void
98initmsgbuf(caddr_t buf, size_t bufsize)
99{
100	struct msgbuf *mbp;
101	long new_bufs;
102
103	/* Sanity-check the given size. */
104	if (bufsize < sizeof(struct msgbuf))
105		return;
106
107	mbp = msgbufp = (struct msgbuf *)buf;
108
109	new_bufs = bufsize - offsetof(struct msgbuf, msg_bufc);
110	if ((mbp->msg_magic != MSG_MAGIC) || (mbp->msg_bufs != new_bufs) ||
111	    (mbp->msg_bufr < 0) || (mbp->msg_bufr >= mbp->msg_bufs) ||
112	    (mbp->msg_bufx < 0) || (mbp->msg_bufx >= mbp->msg_bufs)) {
113		/*
114		 * If the buffer magic number is wrong, has changed
115		 * size (which shouldn't happen often), or is
116		 * internally inconsistent, initialize it.
117		 */
118
119		memset(buf, 0, bufsize);
120		mbp->msg_magic = MSG_MAGIC;
121		mbp->msg_bufs = new_bufs;
122	}
123
124	/* Always start new buffer data on a new line. */
125	if (mbp->msg_bufx > 0 && mbp->msg_bufc[mbp->msg_bufx - 1] != '\n')
126		msgbuf_putchar(msgbufp, '\n');
127
128	/* mark it as ready for use. */
129	msgbufmapped = 1;
130}
131
132void
133initconsbuf(void)
134{
135	/* Set up a buffer to collect /dev/console output */
136	consbufp = malloc(CONSBUFSIZE, M_TTYS, M_WAITOK | M_ZERO);
137	consbufp->msg_magic = MSG_MAGIC;
138	consbufp->msg_bufs = CONSBUFSIZE - offsetof(struct msgbuf, msg_bufc);
139}
140
141void
142msgbuf_putchar(struct msgbuf *mbp, const char c)
143{
144	int s;
145
146	if (mbp->msg_magic != MSG_MAGIC)
147		/* Nothing we can do */
148		return;
149
150	s = splhigh();
151	mbp->msg_bufc[mbp->msg_bufx++] = c;
152	mbp->msg_bufl = lmin(mbp->msg_bufl+1, mbp->msg_bufs);
153	if (mbp->msg_bufx < 0 || mbp->msg_bufx >= mbp->msg_bufs)
154		mbp->msg_bufx = 0;
155	/* If the buffer is full, keep the most recent data. */
156	if (mbp->msg_bufr == mbp->msg_bufx) {
157		if (++mbp->msg_bufr >= mbp->msg_bufs)
158			mbp->msg_bufr = 0;
159		mbp->msg_bufd++;
160	}
161	splx(s);
162}
163
164int
165logopen(dev_t dev, int flags, int mode, struct proc *p)
166{
167	if (log_open)
168		return (EBUSY);
169	log_open = 1;
170	timeout_set(&logsoftc.sc_tick, logtick, NULL);
171	timeout_add_msec(&logsoftc.sc_tick, LOG_TICK);
172	return (0);
173}
174
175int
176logclose(dev_t dev, int flag, int mode, struct proc *p)
177{
178	struct file *fp;
179
180	fp = syslogf;
181	syslogf = NULL;
182	if (fp)
183		FRELE(fp, p);
184	log_open = 0;
185	timeout_del(&logsoftc.sc_tick);
186	logsoftc.sc_state = 0;
187	return (0);
188}
189
190int
191logread(dev_t dev, struct uio *uio, int flag)
192{
193	struct msgbuf *mbp = msgbufp;
194	size_t l;
195	int s, error = 0;
196
197	s = splhigh();
198	while (mbp->msg_bufr == mbp->msg_bufx) {
199		if (flag & IO_NDELAY) {
200			error = EWOULDBLOCK;
201			goto out;
202		}
203		logsoftc.sc_state |= LOG_RDWAIT;
204		error = tsleep(mbp, LOG_RDPRI | PCATCH,
205			       "klog", 0);
206		if (error)
207			goto out;
208	}
209	logsoftc.sc_state &= ~LOG_RDWAIT;
210
211	if (mbp->msg_bufd > 0) {
212		char buf[64];
213
214		l = snprintf(buf, sizeof(buf),
215		    "<%d>klog: dropped %ld byte%s, message buffer full\n",
216		    LOG_KERN|LOG_WARNING, mbp->msg_bufd,
217                    mbp->msg_bufd == 1 ? "" : "s");
218		error = uiomove(buf, ulmin(l, sizeof(buf) - 1), uio);
219		if (error)
220			goto out;
221		mbp->msg_bufd = 0;
222	}
223
224	while (uio->uio_resid > 0) {
225		if (mbp->msg_bufx >= mbp->msg_bufr)
226			l = mbp->msg_bufx - mbp->msg_bufr;
227		else
228			l = mbp->msg_bufs - mbp->msg_bufr;
229		l = ulmin(l, uio->uio_resid);
230		if (l == 0)
231			break;
232		error = uiomove(&mbp->msg_bufc[mbp->msg_bufr], l, uio);
233		if (error)
234			break;
235		mbp->msg_bufr += l;
236		if (mbp->msg_bufr < 0 || mbp->msg_bufr >= mbp->msg_bufs)
237			mbp->msg_bufr = 0;
238	}
239 out:
240	splx(s);
241	return (error);
242}
243
244int
245logpoll(dev_t dev, int events, struct proc *p)
246{
247	int s, revents = 0;
248
249	s = splhigh();
250	if (events & (POLLIN | POLLRDNORM)) {
251		if (msgbufp->msg_bufr != msgbufp->msg_bufx)
252			revents |= events & (POLLIN | POLLRDNORM);
253		else
254			selrecord(p, &logsoftc.sc_selp);
255	}
256	splx(s);
257	return (revents);
258}
259
260int
261logkqfilter(dev_t dev, struct knote *kn)
262{
263	struct klist *klist;
264	int s;
265
266	switch (kn->kn_filter) {
267	case EVFILT_READ:
268		klist = &logsoftc.sc_selp.si_note;
269		kn->kn_fop = &logread_filtops;
270		break;
271	default:
272		return (EINVAL);
273	}
274
275	kn->kn_hook = (void *)msgbufp;
276
277	s = splhigh();
278	SLIST_INSERT_HEAD(klist, kn, kn_selnext);
279	splx(s);
280
281	return (0);
282}
283
284void
285filt_logrdetach(struct knote *kn)
286{
287	int s;
288
289	s = splhigh();
290	SLIST_REMOVE(&logsoftc.sc_selp.si_note, kn, knote, kn_selnext);
291	splx(s);
292}
293
294int
295filt_logread(struct knote *kn, long hint)
296{
297	struct  msgbuf *p = (struct  msgbuf *)kn->kn_hook;
298	int s, event = 0;
299
300	s = splhigh();
301	kn->kn_data = (int)(p->msg_bufx - p->msg_bufr);
302	event = (p->msg_bufx != p->msg_bufr);
303	splx(s);
304	return (event);
305}
306
307void
308logwakeup(void)
309{
310	/*
311	 * The actual wakeup has to be deferred because logwakeup() can be
312	 * called in very varied contexts.
313	 * Keep the print routines usable in as many situations as possible
314	 * by not using locking here.
315	 */
316
317	/*
318	 * Ensure that preceding stores become visible to other CPUs
319	 * before the flag.
320	 */
321	membar_producer();
322
323	logsoftc.sc_need_wakeup = 1;
324}
325
326void
327logtick(void *arg)
328{
329	if (!log_open)
330		return;
331
332	if (!logsoftc.sc_need_wakeup)
333		goto out;
334	logsoftc.sc_need_wakeup = 0;
335
336	/*
337	 * sc_need_wakeup has to be cleared before handling the wakeup.
338	 * This ensures that no wakeup is lost.
339	 */
340	membar_enter();
341
342	selwakeup(&logsoftc.sc_selp);
343	if (logsoftc.sc_state & LOG_ASYNC)
344		csignal(logsoftc.sc_pgid, SIGIO,
345		    logsoftc.sc_siguid, logsoftc.sc_sigeuid);
346	if (logsoftc.sc_state & LOG_RDWAIT) {
347		wakeup(msgbufp);
348		logsoftc.sc_state &= ~LOG_RDWAIT;
349	}
350out:
351	timeout_add_msec(&logsoftc.sc_tick, LOG_TICK);
352}
353
354int
355logioctl(dev_t dev, u_long com, caddr_t data, int flag, struct proc *p)
356{
357	struct file *fp;
358	long l;
359	int error, s;
360
361	switch (com) {
362
363	/* return number of characters immediately available */
364	case FIONREAD:
365		s = splhigh();
366		l = msgbufp->msg_bufx - msgbufp->msg_bufr;
367		splx(s);
368		if (l < 0)
369			l += msgbufp->msg_bufs;
370		*(int *)data = l;
371		break;
372
373	case FIONBIO:
374		break;
375
376	case FIOASYNC:
377		if (*(int *)data)
378			logsoftc.sc_state |= LOG_ASYNC;
379		else
380			logsoftc.sc_state &= ~LOG_ASYNC;
381		break;
382
383	case TIOCSPGRP:
384		logsoftc.sc_pgid = *(int *)data;
385		logsoftc.sc_siguid = p->p_ucred->cr_ruid;
386		logsoftc.sc_sigeuid = p->p_ucred->cr_uid;
387		break;
388
389	case TIOCGPGRP:
390		*(int *)data = logsoftc.sc_pgid;
391		break;
392
393	case LIOCSFD:
394		if ((error = suser(p)) != 0)
395			return (error);
396		fp = syslogf;
397		if ((error = getsock(p, *(int *)data, &syslogf)) != 0)
398			return (error);
399		if (fp)
400			FRELE(fp, p);
401		break;
402
403	default:
404		return (ENOTTY);
405	}
406	return (0);
407}
408
409int
410sys_sendsyslog(struct proc *p, void *v, register_t *retval)
411{
412	struct sys_sendsyslog_args /* {
413		syscallarg(const char *) buf;
414		syscallarg(size_t) nbyte;
415		syscallarg(int) flags;
416	} */ *uap = v;
417	int error;
418	static int dropped_count, orig_error, orig_pid;
419
420	if (dropped_count) {
421		size_t l;
422		char buf[80];
423
424		l = snprintf(buf, sizeof(buf),
425		    "<%d>sendsyslog: dropped %d message%s, error %d, pid %d",
426		    LOG_KERN|LOG_WARNING, dropped_count,
427		    dropped_count == 1 ? "" : "s", orig_error, orig_pid);
428		error = dosendsyslog(p, buf, ulmin(l, sizeof(buf) - 1),
429		    0, UIO_SYSSPACE);
430		if (error == 0) {
431			dropped_count = 0;
432			orig_error = 0;
433			orig_pid = 0;
434		}
435	}
436	error = dosendsyslog(p, SCARG(uap, buf), SCARG(uap, nbyte),
437	    SCARG(uap, flags), UIO_USERSPACE);
438	if (error) {
439		dropped_count++;
440		orig_error = error;
441		orig_pid = p->p_p->ps_pid;
442	}
443	return (error);
444}
445
446int
447dosendsyslog(struct proc *p, const char *buf, size_t nbyte, int flags,
448    enum uio_seg sflg)
449{
450#ifdef KTRACE
451	struct iovec ktriov;
452#endif
453	struct file *fp;
454	char pri[6], *kbuf;
455	struct iovec aiov;
456	struct uio auio;
457	size_t i, len;
458	int error;
459
460	if (nbyte > LOG_MAXLINE)
461		nbyte = LOG_MAXLINE;
462
463	/* Global variable syslogf may change during sleep, use local copy. */
464	fp = syslogf;
465	if (fp)
466		FREF(fp);
467	else if (!ISSET(flags, LOG_CONS))
468		return (ENOTCONN);
469	else {
470		/*
471		 * Strip off syslog priority when logging to console.
472		 * LOG_PRIMASK | LOG_FACMASK is 0x03ff, so at most 4
473		 * decimal digits may appear in priority as <1023>.
474		 */
475		len = MIN(nbyte, sizeof(pri));
476		if (sflg == UIO_USERSPACE) {
477			if ((error = copyin(buf, pri, len)))
478				return (error);
479		} else
480			memcpy(pri, buf, len);
481		if (0 < len && pri[0] == '<') {
482			for (i = 1; i < len; i++) {
483				if (pri[i] < '0' || pri[i] > '9')
484					break;
485			}
486			if (i < len && pri[i] == '>') {
487				i++;
488				/* There must be at least one digit <0>. */
489				if (i >= 3) {
490					buf += i;
491					nbyte -= i;
492				}
493			}
494		}
495	}
496
497	aiov.iov_base = (char *)buf;
498	aiov.iov_len = nbyte;
499	auio.uio_iov = &aiov;
500	auio.uio_iovcnt = 1;
501	auio.uio_segflg = sflg;
502	auio.uio_rw = UIO_WRITE;
503	auio.uio_procp = p;
504	auio.uio_offset = 0;
505	auio.uio_resid = aiov.iov_len;
506#ifdef KTRACE
507	if (sflg == UIO_USERSPACE && KTRPOINT(p, KTR_GENIO))
508		ktriov = aiov;
509	else
510		ktriov.iov_len = 0;
511#endif
512
513	len = auio.uio_resid;
514	if (fp) {
515		int flags = (fp->f_flag & FNONBLOCK) ? MSG_DONTWAIT : 0;
516		error = sosend(fp->f_data, NULL, &auio, NULL, NULL, flags);
517		if (error == 0)
518			len -= auio.uio_resid;
519	} else if (constty || cn_devvp) {
520		error = cnwrite(0, &auio, 0);
521		if (error == 0)
522			len -= auio.uio_resid;
523		aiov.iov_base = "\r\n";
524		aiov.iov_len = 2;
525		auio.uio_iov = &aiov;
526		auio.uio_iovcnt = 1;
527		auio.uio_segflg = UIO_SYSSPACE;
528		auio.uio_rw = UIO_WRITE;
529		auio.uio_procp = p;
530		auio.uio_offset = 0;
531		auio.uio_resid = aiov.iov_len;
532		cnwrite(0, &auio, 0);
533	} else {
534		/* XXX console redirection breaks down... */
535		if (sflg == UIO_USERSPACE) {
536			kbuf = malloc(len, M_TEMP, M_WAITOK);
537			error = copyin(aiov.iov_base, kbuf, len);
538		} else {
539			kbuf = aiov.iov_base;
540			error = 0;
541		}
542		if (error == 0)
543			for (i = 0; i < len; i++) {
544				if (kbuf[i] == '\0')
545					break;
546				cnputc(kbuf[i]);
547				auio.uio_resid--;
548			}
549		if (sflg == UIO_USERSPACE)
550			free(kbuf, M_TEMP, len);
551		if (error == 0)
552			len -= auio.uio_resid;
553		cnputc('\n');
554	}
555
556#ifdef KTRACE
557	if (error == 0 && ktriov.iov_len != 0)
558		ktrgenio(p, -1, UIO_WRITE, &ktriov, len);
559#endif
560	if (fp)
561		FRELE(fp, p);
562	else
563		error = ENOTCONN;
564	return (error);
565}
566