subr_log.c revision 1.35 
1/*	$OpenBSD: subr_log.c,v 1.35 2016/01/01 19:15:00 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
69struct 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
77int	log_open;			/* also used in log() */
78int	msgbufmapped;			/* is the message buffer mapped */
79struct	msgbuf *msgbufp;		/* the mapped buffer, itself. */
80struct	msgbuf *consbufp;		/* console message buffer. */
81struct	file *syslogf;
82
83void filt_logrdetach(struct knote *kn);
84int filt_logread(struct knote *kn, long hint);
85
86struct filterops logread_filtops =
87	{ 1, NULL, filt_logrdetach, filt_logread};
88
89int dosendsyslog(struct proc *, const char *, size_t, int, enum uio_seg);
90
91void
92initmsgbuf(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
126void
127initconsbuf(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
140void
141msgbuf_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
158int
159logopen(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
167int
168logclose(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
179int
180logread(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
221int
222logpoll(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
237int
238logkqfilter(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
261void
262filt_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
270int
271filt_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
280void
281logwakeup(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
295int
296logioctl(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
350int
351sys_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
365int
366sys_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
401int
402dosendsyslog(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	struct iovec aiov;
410	struct uio auio;
411	size_t len;
412	int error;
413
414	if (syslogf == NULL && (flags & LOG_CONS) == 0)
415		return (ENOTCONN);
416	if (syslogf)
417		FREF(syslogf);
418
419	aiov.iov_base = (char *)buf;
420	aiov.iov_len = nbyte;
421	auio.uio_iov = &aiov;
422	auio.uio_iovcnt = 1;
423	auio.uio_segflg = sflg;
424	auio.uio_rw = UIO_WRITE;
425	auio.uio_procp = p;
426	auio.uio_offset = 0;
427	auio.uio_resid = aiov.iov_len;
428#ifdef KTRACE
429	if (KTRPOINT(p, KTR_GENIO)) {
430		ktriov = mallocarray(auio.uio_iovcnt, sizeof(struct iovec),
431		    M_TEMP, M_WAITOK);
432		iovlen = auio.uio_iovcnt * sizeof (struct iovec);
433
434		memcpy(ktriov, auio.uio_iov, iovlen);
435	}
436#endif
437
438	len = auio.uio_resid;
439	if (syslogf)
440		error = sosend(syslogf->f_data, NULL, &auio, NULL, NULL, 0);
441	else
442		error = cnwrite(0, &auio, 0);
443	if (error == 0)
444		len -= auio.uio_resid;
445	if (syslogf == NULL) {
446		aiov.iov_base = "\r\n";
447		aiov.iov_len = 2;
448		auio.uio_iov = &aiov;
449		auio.uio_iovcnt = 1;
450		auio.uio_segflg = UIO_SYSSPACE;
451		auio.uio_rw = UIO_WRITE;
452		auio.uio_procp = p;
453		auio.uio_offset = 0;
454		auio.uio_resid = aiov.iov_len;
455		cnwrite(0, &auio, 0);
456	}
457
458#ifdef KTRACE
459	if (ktriov != NULL) {
460		if (error == 0)
461			ktrgenio(p, -1, UIO_WRITE, ktriov, len);
462		free(ktriov, M_TEMP, iovlen);
463	}
464#endif
465	if (syslogf)
466		FRELE(syslogf, p);
467	else
468		error = ENOTCONN;
469	return (error);
470}
471