xref: /openbsd-src/sys/kern/subr_log.c (revision 4566e8afcfc484b82cc9ed84724ca64a42ba75ba) 
1 /*	$OpenBSD: subr_log.c,v 1.36 2016/01/07 12:27:07 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 
55 #ifdef KTRACE
56 #include <sys/ktrace.h>
57 #endif
58 
59 #include <sys/mount.h>
60 #include <sys/syscallargs.h>
61 
62 #include <dev/cons.h>
63 
64 #define LOG_RDPRI	(PZERO + 1)
65 
66 #define LOG_ASYNC	0x04
67 #define LOG_RDWAIT	0x08
68 
69 struct logsoftc {
70 	int	sc_state;		/* see above for possibilities */
71 	struct	selinfo sc_selp;	/* process waiting on select call */
72 	int	sc_pgid;		/* process/group for async I/O */
73 	uid_t	sc_siguid;		/* uid for process that set sc_pgid */
74 	uid_t	sc_sigeuid;		/* euid for process that set sc_pgid */
75 } logsoftc;
76 
77 int	log_open;			/* also used in log() */
78 int	msgbufmapped;			/* is the message buffer mapped */
79 struct	msgbuf *msgbufp;		/* the mapped buffer, itself. */
80 struct	msgbuf *consbufp;		/* console message buffer. */
81 struct	file *syslogf;
82 
83 void filt_logrdetach(struct knote *kn);
84 int filt_logread(struct knote *kn, long hint);
85 
86 struct filterops logread_filtops =
87 	{ 1, NULL, filt_logrdetach, filt_logread};
88 
89 int dosendsyslog(struct proc *, const char *, size_t, int, enum uio_seg);
90 
91 void
92 initmsgbuf(caddr_t buf, size_t bufsize)
93 {
94 	struct msgbuf *mbp;
95 	long new_bufs;
96 
97 	/* Sanity-check the given size. */
98 	if (bufsize < sizeof(struct msgbuf))
99 		return;
100 
101 	mbp = msgbufp = (struct msgbuf *)buf;
102 
103 	new_bufs = bufsize - offsetof(struct msgbuf, msg_bufc);
104 	if ((mbp->msg_magic != MSG_MAGIC) || (mbp->msg_bufs != new_bufs) ||
105 	    (mbp->msg_bufr < 0) || (mbp->msg_bufr >= mbp->msg_bufs) ||
106 	    (mbp->msg_bufx < 0) || (mbp->msg_bufx >= mbp->msg_bufs)) {
107 		/*
108 		 * If the buffer magic number is wrong, has changed
109 		 * size (which shouldn't happen often), or is
110 		 * internally inconsistent, initialize it.
111 		 */
112 
113 		memset(buf, 0, bufsize);
114 		mbp->msg_magic = MSG_MAGIC;
115 		mbp->msg_bufs = new_bufs;
116 	}
117 
118 	/* Always start new buffer data on a new line. */
119 	if (mbp->msg_bufx > 0 && mbp->msg_bufc[mbp->msg_bufx - 1] != '\n')
120 		msgbuf_putchar(msgbufp, '\n');
121 
122 	/* mark it as ready for use. */
123 	msgbufmapped = 1;
124 }
125 
126 void
127 initconsbuf(void)
128 {
129 	long new_bufs;
130 
131 	/* Set up a buffer to collect /dev/console output */
132 	consbufp = malloc(CONSBUFSIZE, M_TEMP, M_NOWAIT|M_ZERO);
133 	if (consbufp) {
134 		new_bufs = CONSBUFSIZE - offsetof(struct msgbuf, msg_bufc);
135 		consbufp->msg_magic = MSG_MAGIC;
136 		consbufp->msg_bufs = new_bufs;
137 	}
138 }
139 
140 void
141 msgbuf_putchar(struct msgbuf *mbp, const char c)
142 {
143 	if (mbp->msg_magic != MSG_MAGIC)
144 		/* Nothing we can do */
145 		return;
146 
147 	mbp->msg_bufc[mbp->msg_bufx++] = c;
148 	mbp->msg_bufl = min(mbp->msg_bufl+1, mbp->msg_bufs);
149 	if (mbp->msg_bufx < 0 || mbp->msg_bufx >= mbp->msg_bufs)
150 		mbp->msg_bufx = 0;
151 	/* If the buffer is full, keep the most recent data. */
152 	if (mbp->msg_bufr == mbp->msg_bufx) {
153 		if (++mbp->msg_bufr >= mbp->msg_bufs)
154 			mbp->msg_bufr = 0;
155 	}
156 }
157 
158 int
159 logopen(dev_t dev, int flags, int mode, struct proc *p)
160 {
161 	if (log_open)
162 		return (EBUSY);
163 	log_open = 1;
164 	return (0);
165 }
166 
167 int
168 logclose(dev_t dev, int flag, int mode, struct proc *p)
169 {
170 
171 	if (syslogf)
172 		FRELE(syslogf, p);
173 	syslogf = NULL;
174 	log_open = 0;
175 	logsoftc.sc_state = 0;
176 	return (0);
177 }
178 
179 int
180 logread(dev_t dev, struct uio *uio, int flag)
181 {
182 	struct msgbuf *mbp = msgbufp;
183 	long l;
184 	int s;
185 	int error = 0;
186 
187 	s = splhigh();
188 	while (mbp->msg_bufr == mbp->msg_bufx) {
189 		if (flag & IO_NDELAY) {
190 			splx(s);
191 			return (EWOULDBLOCK);
192 		}
193 		logsoftc.sc_state |= LOG_RDWAIT;
194 		error = tsleep(mbp, LOG_RDPRI | PCATCH,
195 			       "klog", 0);
196 		if (error) {
197 			splx(s);
198 			return (error);
199 		}
200 	}
201 	splx(s);
202 	logsoftc.sc_state &= ~LOG_RDWAIT;
203 
204 	while (uio->uio_resid > 0) {
205 		l = mbp->msg_bufx - mbp->msg_bufr;
206 		if (l < 0)
207 			l = mbp->msg_bufs - mbp->msg_bufr;
208 		l = min(l, uio->uio_resid);
209 		if (l == 0)
210 			break;
211 		error = uiomovei(&mbp->msg_bufc[mbp->msg_bufr], (int)l, uio);
212 		if (error)
213 			break;
214 		mbp->msg_bufr += l;
215 		if (mbp->msg_bufr < 0 || mbp->msg_bufr >= mbp->msg_bufs)
216 			mbp->msg_bufr = 0;
217 	}
218 	return (error);
219 }
220 
221 int
222 logpoll(dev_t dev, int events, struct proc *p)
223 {
224 	int revents = 0;
225 	int s = splhigh();
226 
227 	if (events & (POLLIN | POLLRDNORM)) {
228 		if (msgbufp->msg_bufr != msgbufp->msg_bufx)
229 			revents |= events & (POLLIN | POLLRDNORM);
230 		else
231 			selrecord(p, &logsoftc.sc_selp);
232 	}
233 	splx(s);
234 	return (revents);
235 }
236 
237 int
238 logkqfilter(dev_t dev, struct knote *kn)
239 {
240 	struct klist *klist;
241 	int s;
242 
243 	switch (kn->kn_filter) {
244 	case EVFILT_READ:
245 		klist = &logsoftc.sc_selp.si_note;
246 		kn->kn_fop = &logread_filtops;
247 		break;
248 	default:
249 		return (EINVAL);
250 	}
251 
252 	kn->kn_hook = (void *)msgbufp;
253 
254 	s = splhigh();
255 	SLIST_INSERT_HEAD(klist, kn, kn_selnext);
256 	splx(s);
257 
258 	return (0);
259 }
260 
261 void
262 filt_logrdetach(struct knote *kn)
263 {
264 	int s = splhigh();
265 
266 	SLIST_REMOVE(&logsoftc.sc_selp.si_note, kn, knote, kn_selnext);
267 	splx(s);
268 }
269 
270 int
271 filt_logread(struct knote *kn, long hint)
272 {
273 	struct  msgbuf *p = (struct  msgbuf *)kn->kn_hook;
274 
275 	kn->kn_data = (int)(p->msg_bufx - p->msg_bufr);
276 
277 	return (p->msg_bufx != p->msg_bufr);
278 }
279 
280 void
281 logwakeup(void)
282 {
283 	if (!log_open)
284 		return;
285 	selwakeup(&logsoftc.sc_selp);
286 	if (logsoftc.sc_state & LOG_ASYNC)
287 		csignal(logsoftc.sc_pgid, SIGIO,
288 		    logsoftc.sc_siguid, logsoftc.sc_sigeuid);
289 	if (logsoftc.sc_state & LOG_RDWAIT) {
290 		wakeup(msgbufp);
291 		logsoftc.sc_state &= ~LOG_RDWAIT;
292 	}
293 }
294 
295 int
296 logioctl(dev_t dev, u_long com, caddr_t data, int flag, struct proc *p)
297 {
298 	struct file *fp;
299 	long l;
300 	int error, s;
301 
302 	switch (com) {
303 
304 	/* return number of characters immediately available */
305 	case FIONREAD:
306 		s = splhigh();
307 		l = msgbufp->msg_bufx - msgbufp->msg_bufr;
308 		splx(s);
309 		if (l < 0)
310 			l += msgbufp->msg_bufs;
311 		*(int *)data = l;
312 		break;
313 
314 	case FIONBIO:
315 		break;
316 
317 	case FIOASYNC:
318 		if (*(int *)data)
319 			logsoftc.sc_state |= LOG_ASYNC;
320 		else
321 			logsoftc.sc_state &= ~LOG_ASYNC;
322 		break;
323 
324 	case TIOCSPGRP:
325 		logsoftc.sc_pgid = *(int *)data;
326 		logsoftc.sc_siguid = p->p_ucred->cr_ruid;
327 		logsoftc.sc_sigeuid = p->p_ucred->cr_uid;
328 		break;
329 
330 	case TIOCGPGRP:
331 		*(int *)data = logsoftc.sc_pgid;
332 		break;
333 
334 	case LIOCSFD:
335 		if ((error = suser(p, 0)) != 0)
336 			return (error);
337 		if ((error = getsock(p, *(int *)data, &fp)) != 0)
338 			return (error);
339 		if (syslogf)
340 			FRELE(syslogf, p);
341 		syslogf = fp;
342 		break;
343 
344 	default:
345 		return (ENOTTY);
346 	}
347 	return (0);
348 }
349 
350 int
351 sys_sendsyslog(struct proc *p, void *v, register_t *retval)
352 {
353 	struct sys_sendsyslog_args /* {
354 		syscallarg(const void *) buf;
355 		syscallarg(size_t) nbyte;
356 	} */ *uap = v;
357 	struct sys_sendsyslog2_args oap;
358 
359 	SCARG(&oap, buf) = SCARG(uap, buf);
360 	SCARG(&oap, nbyte) = SCARG(uap, nbyte);
361 	SCARG(&oap, flags) = 0;
362 	return sys_sendsyslog2(p, &oap, retval);
363 }
364 
365 int
366 sys_sendsyslog2(struct proc *p, void *v, register_t *retval)
367 {
368 	struct sys_sendsyslog2_args /* {
369 		syscallarg(const void *) buf;
370 		syscallarg(size_t) nbyte;
371 		syscallarg(int) flags;
372 	} */ *uap = v;
373 	int error;
374 #ifndef SMALL_KERNEL
375 	static int dropped_count, orig_error;
376 	int len;
377 	char buf[64];
378 
379 	if (dropped_count) {
380 		len = snprintf(buf, sizeof(buf),
381 		    "<%d>sendsyslog: dropped %d message%s, error %d",
382 		    LOG_KERN|LOG_WARNING, dropped_count,
383 		    dropped_count == 1 ? "" : "s", orig_error);
384 		error = dosendsyslog(p, buf, MIN((size_t)len, sizeof(buf) - 1),
385 		    0, UIO_SYSSPACE);
386 		if (error == 0)
387 			dropped_count = 0;
388 	}
389 #endif
390 	error = dosendsyslog(p, SCARG(uap, buf), SCARG(uap, nbyte),
391 	    SCARG(uap, flags), UIO_USERSPACE);
392 #ifndef SMALL_KERNEL
393 	if (error) {
394 		dropped_count++;
395 		orig_error = error;
396 	}
397 #endif
398 	return (error);
399 }
400 
401 int
402 dosendsyslog(struct proc *p, const char *buf, size_t nbyte, int flags,
403     enum uio_seg sflg)
404 {
405 #ifdef KTRACE
406 	struct iovec *ktriov = NULL;
407 	int iovlen;
408 #endif
409 	char pri[6];
410 	struct iovec aiov;
411 	struct uio auio;
412 	size_t i, len;
413 	int error;
414 
415 	if (syslogf)
416 		FREF(syslogf);
417 	else if ((flags & LOG_CONS) == 0)
418 		return (ENOTCONN);
419 	else {
420 		/*
421 		 * Strip off syslog priority when logging to console.
422 		 * LOG_PRIMASK | LOG_FACMASK is 0x03ff, so at most 4
423 		 * decimal digits may appear in priority as <1023>.
424 		 */
425 		len = MIN(nbyte, sizeof(pri));
426 		if (sflg == UIO_USERSPACE) {
427 			if ((error = copyin(buf, pri, len)))
428 				return (error);
429 		} else
430 			memcpy(pri, buf, len);
431 		if (0 < len && pri[0] == '<') {
432 			for (i = 1; i < len; i++) {
433 				if (pri[i] < '0' || pri[i] > '9')
434 					break;
435 			}
436 			if (i < len && pri[i] == '>') {
437 				i++;
438 				/* There must be at least one digit <0>. */
439 				if (i >= 3) {
440 					buf += i;
441 					nbyte -= i;
442 				}
443 			}
444 		}
445 	}
446 
447 	aiov.iov_base = (char *)buf;
448 	aiov.iov_len = nbyte;
449 	auio.uio_iov = &aiov;
450 	auio.uio_iovcnt = 1;
451 	auio.uio_segflg = sflg;
452 	auio.uio_rw = UIO_WRITE;
453 	auio.uio_procp = p;
454 	auio.uio_offset = 0;
455 	auio.uio_resid = aiov.iov_len;
456 #ifdef KTRACE
457 	if (KTRPOINT(p, KTR_GENIO)) {
458 		ktriov = mallocarray(auio.uio_iovcnt, sizeof(struct iovec),
459 		    M_TEMP, M_WAITOK);
460 		iovlen = auio.uio_iovcnt * sizeof (struct iovec);
461 
462 		memcpy(ktriov, auio.uio_iov, iovlen);
463 	}
464 #endif
465 
466 	len = auio.uio_resid;
467 	if (syslogf)
468 		error = sosend(syslogf->f_data, NULL, &auio, NULL, NULL, 0);
469 	else
470 		error = cnwrite(0, &auio, 0);
471 	if (error == 0)
472 		len -= auio.uio_resid;
473 	if (syslogf == NULL) {
474 		aiov.iov_base = "\r\n";
475 		aiov.iov_len = 2;
476 		auio.uio_iov = &aiov;
477 		auio.uio_iovcnt = 1;
478 		auio.uio_segflg = UIO_SYSSPACE;
479 		auio.uio_rw = UIO_WRITE;
480 		auio.uio_procp = p;
481 		auio.uio_offset = 0;
482 		auio.uio_resid = aiov.iov_len;
483 		cnwrite(0, &auio, 0);
484 	}
485 
486 #ifdef KTRACE
487 	if (ktriov != NULL) {
488 		if (error == 0)
489 			ktrgenio(p, -1, UIO_WRITE, ktriov, len);
490 		free(ktriov, M_TEMP, iovlen);
491 	}
492 #endif
493 	if (syslogf)
494 		FRELE(syslogf, p);
495 	else
496 		error = ENOTCONN;
497 	return (error);
498 }
499