subr_log.c revision 1.31 
1/*	$OpenBSD: subr_log.c,v 1.31 2015/09/02 13:21:37 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/signalvar.h>
47#include <sys/syslog.h>
48#include <sys/poll.h>
49#include <sys/malloc.h>
50#include <sys/filedesc.h>
51#include <sys/socket.h>
52#include <sys/socketvar.h>
53
54#ifdef KTRACE
55#include <sys/ktrace.h>
56#endif
57
58#include <sys/mount.h>
59#include <sys/syscallargs.h>
60
61#define LOG_RDPRI	(PZERO + 1)
62
63#define LOG_ASYNC	0x04
64#define LOG_RDWAIT	0x08
65
66struct logsoftc {
67	int	sc_state;		/* see above for possibilities */
68	struct	selinfo sc_selp;	/* process waiting on select call */
69	int	sc_pgid;		/* process/group for async I/O */
70	uid_t	sc_siguid;		/* uid for process that set sc_pgid */
71	uid_t	sc_sigeuid;		/* euid for process that set sc_pgid */
72} logsoftc;
73
74int	log_open;			/* also used in log() */
75int	msgbufmapped;			/* is the message buffer mapped */
76struct	msgbuf *msgbufp;		/* the mapped buffer, itself. */
77struct	msgbuf *consbufp;		/* console message buffer. */
78struct file *syslogf;
79
80void filt_logrdetach(struct knote *kn);
81int filt_logread(struct knote *kn, long hint);
82
83struct filterops logread_filtops =
84	{ 1, NULL, filt_logrdetach, filt_logread};
85
86int dosendsyslog(struct proc *, const char *, size_t, enum uio_seg);
87
88void
89initmsgbuf(caddr_t buf, size_t bufsize)
90{
91	struct msgbuf *mbp;
92	long new_bufs;
93
94	/* Sanity-check the given size. */
95	if (bufsize < sizeof(struct msgbuf))
96		return;
97
98	mbp = msgbufp = (struct msgbuf *)buf;
99
100	new_bufs = bufsize - offsetof(struct msgbuf, msg_bufc);
101	if ((mbp->msg_magic != MSG_MAGIC) || (mbp->msg_bufs != new_bufs) ||
102	    (mbp->msg_bufr < 0) || (mbp->msg_bufr >= mbp->msg_bufs) ||
103	    (mbp->msg_bufx < 0) || (mbp->msg_bufx >= mbp->msg_bufs)) {
104		/*
105		 * If the buffer magic number is wrong, has changed
106		 * size (which shouldn't happen often), or is
107		 * internally inconsistent, initialize it.
108		 */
109
110		memset(buf, 0, bufsize);
111		mbp->msg_magic = MSG_MAGIC;
112		mbp->msg_bufs = new_bufs;
113	}
114
115	/* Always start new buffer data on a new line. */
116	if (mbp->msg_bufx > 0 && mbp->msg_bufc[mbp->msg_bufx - 1] != '\n')
117		msgbuf_putchar(msgbufp, '\n');
118
119	/* mark it as ready for use. */
120	msgbufmapped = 1;
121}
122
123void
124initconsbuf(void)
125{
126	long new_bufs;
127
128	/* Set up a buffer to collect /dev/console output */
129	consbufp = malloc(CONSBUFSIZE, M_TEMP, M_NOWAIT|M_ZERO);
130	if (consbufp) {
131		new_bufs = CONSBUFSIZE - offsetof(struct msgbuf, msg_bufc);
132		consbufp->msg_magic = MSG_MAGIC;
133		consbufp->msg_bufs = new_bufs;
134	}
135}
136
137void
138msgbuf_putchar(struct msgbuf *mbp, const char c)
139{
140	if (mbp->msg_magic != MSG_MAGIC)
141		/* Nothing we can do */
142		return;
143
144	mbp->msg_bufc[mbp->msg_bufx++] = c;
145	mbp->msg_bufl = min(mbp->msg_bufl+1, mbp->msg_bufs);
146	if (mbp->msg_bufx < 0 || mbp->msg_bufx >= mbp->msg_bufs)
147		mbp->msg_bufx = 0;
148	/* If the buffer is full, keep the most recent data. */
149	if (mbp->msg_bufr == mbp->msg_bufx) {
150		if (++mbp->msg_bufr >= mbp->msg_bufs)
151			mbp->msg_bufr = 0;
152	}
153}
154
155/*ARGSUSED*/
156int
157logopen(dev_t dev, int flags, int mode, struct proc *p)
158{
159	if (log_open)
160		return (EBUSY);
161	log_open = 1;
162	return (0);
163}
164
165/*ARGSUSED*/
166int
167logclose(dev_t dev, int flag, int mode, struct proc *p)
168{
169
170	if (syslogf)
171		FRELE(syslogf, p);
172	syslogf = NULL;
173	log_open = 0;
174	logsoftc.sc_state = 0;
175	return (0);
176}
177
178/*ARGSUSED*/
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
221/*ARGSUSED*/
222int
223logpoll(dev_t dev, int events, struct proc *p)
224{
225	int revents = 0;
226	int s = splhigh();
227
228	if (events & (POLLIN | POLLRDNORM)) {
229		if (msgbufp->msg_bufr != msgbufp->msg_bufx)
230			revents |= events & (POLLIN | POLLRDNORM);
231		else
232			selrecord(p, &logsoftc.sc_selp);
233	}
234	splx(s);
235	return (revents);
236}
237
238int
239logkqfilter(dev_t dev, struct knote *kn)
240{
241	struct klist *klist;
242	int s;
243
244	switch (kn->kn_filter) {
245	case EVFILT_READ:
246		klist = &logsoftc.sc_selp.si_note;
247		kn->kn_fop = &logread_filtops;
248		break;
249	default:
250		return (EINVAL);
251	}
252
253	kn->kn_hook = (void *)msgbufp;
254
255	s = splhigh();
256	SLIST_INSERT_HEAD(klist, kn, kn_selnext);
257	splx(s);
258
259	return (0);
260}
261
262void
263filt_logrdetach(struct knote *kn)
264{
265	int s = splhigh();
266
267	SLIST_REMOVE(&logsoftc.sc_selp.si_note, kn, knote, kn_selnext);
268	splx(s);
269}
270
271int
272filt_logread(struct knote *kn, long hint)
273{
274	struct  msgbuf *p = (struct  msgbuf *)kn->kn_hook;
275
276	kn->kn_data = (int)(p->msg_bufx - p->msg_bufr);
277
278	return (p->msg_bufx != p->msg_bufr);
279}
280
281void
282logwakeup(void)
283{
284	if (!log_open)
285		return;
286	selwakeup(&logsoftc.sc_selp);
287	if (logsoftc.sc_state & LOG_ASYNC)
288		csignal(logsoftc.sc_pgid, SIGIO,
289		    logsoftc.sc_siguid, logsoftc.sc_sigeuid);
290	if (logsoftc.sc_state & LOG_RDWAIT) {
291		wakeup(msgbufp);
292		logsoftc.sc_state &= ~LOG_RDWAIT;
293	}
294}
295
296/*ARGSUSED*/
297int
298logioctl(dev_t dev, u_long com, caddr_t data, int flag, struct proc *p)
299{
300	struct file *fp;
301	long l;
302	int error, s;
303
304	switch (com) {
305
306	/* return number of characters immediately available */
307	case FIONREAD:
308		s = splhigh();
309		l = msgbufp->msg_bufx - msgbufp->msg_bufr;
310		splx(s);
311		if (l < 0)
312			l += msgbufp->msg_bufs;
313		*(int *)data = l;
314		break;
315
316	case FIONBIO:
317		break;
318
319	case FIOASYNC:
320		if (*(int *)data)
321			logsoftc.sc_state |= LOG_ASYNC;
322		else
323			logsoftc.sc_state &= ~LOG_ASYNC;
324		break;
325
326	case TIOCSPGRP:
327		logsoftc.sc_pgid = *(int *)data;
328		logsoftc.sc_siguid = p->p_ucred->cr_ruid;
329		logsoftc.sc_sigeuid = p->p_ucred->cr_uid;
330		break;
331
332	case TIOCGPGRP:
333		*(int *)data = logsoftc.sc_pgid;
334		break;
335
336	case LIOCSFD:
337		if ((error = suser(p, 0)) != 0)
338			return (error);
339		if ((error = getsock(p, *(int *)data, &fp)) != 0)
340			return (error);
341		if (syslogf)
342			FRELE(syslogf, p);
343		syslogf = fp;
344		break;
345
346	default:
347		return (ENOTTY);
348	}
349	return (0);
350}
351
352int
353sys_sendsyslog(struct proc *p, void *v, register_t *retval)
354{
355	struct sys_sendsyslog_args /* {
356		syscallarg(const void *) buf;
357		syscallarg(size_t) nbyte;
358	} */ *uap = v;
359	int error;
360#ifndef SMALL_KERNEL
361	static int dropped_count, orig_error;
362	int len;
363	char buf[64];
364
365	if (dropped_count) {
366		len = snprintf(buf, sizeof(buf),
367		    "<%d> sendsyslog: dropped %d message%s, error %d",
368		    LOG_KERN|LOG_WARNING, dropped_count,
369		    dropped_count == 1 ? "" : "s", orig_error);
370		error = dosendsyslog(p, buf, MIN((size_t)len, sizeof(buf) - 1),
371		    UIO_SYSSPACE);
372		if (error) {
373			dropped_count++;
374			return (error);
375		}
376		dropped_count = 0;
377	}
378#endif
379	error = dosendsyslog(p, SCARG(uap, buf), SCARG(uap, nbyte),
380	    UIO_USERSPACE);
381#ifndef SMALL_KERNEL
382	if (error) {
383		dropped_count++;
384		orig_error = error;
385	}
386#endif
387	return (error);
388}
389
390int
391dosendsyslog(struct proc *p, const char *buf, size_t nbyte, enum uio_seg sflg)
392{
393#ifdef KTRACE
394	struct iovec *ktriov = NULL;
395	int iovlen;
396#endif
397	struct iovec aiov;
398	struct uio auio;
399	struct file *f;
400	size_t len;
401	int error;
402
403	if (syslogf == NULL)
404		return (ENOTCONN);
405	f = syslogf;
406	FREF(f);
407
408	aiov.iov_base = (char *)buf;
409	aiov.iov_len = nbyte;
410	auio.uio_iov = &aiov;
411	auio.uio_iovcnt = 1;
412	auio.uio_segflg = sflg;
413	auio.uio_rw = UIO_WRITE;
414	auio.uio_procp = p;
415	auio.uio_offset = 0;
416	auio.uio_resid = aiov.iov_len;
417#ifdef KTRACE
418	if (KTRPOINT(p, KTR_GENIO)) {
419		ktriov = mallocarray(auio.uio_iovcnt, sizeof(struct iovec),
420		    M_TEMP, M_WAITOK);
421		iovlen = auio.uio_iovcnt * sizeof (struct iovec);
422
423		memcpy(ktriov, auio.uio_iov, iovlen);
424	}
425#endif
426
427	len = auio.uio_resid;
428	error = sosend(f->f_data, NULL, &auio, NULL, NULL, 0);
429	if (error == 0)
430		len -= auio.uio_resid;
431
432#ifdef KTRACE
433	if (ktriov != NULL) {
434		if (error == 0)
435			ktrgenio(p, -1, UIO_WRITE, ktriov, len);
436		free(ktriov, M_TEMP, iovlen);
437	}
438#endif
439	FRELE(f, p);
440	return error;
441}
442