subr_log.c revision 1.34 
1/*	$OpenBSD: subr_log.c,v 1.34 2015/12/05 10:11:53 tedu 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#define LOG_RDPRI	(PZERO + 1)
63
64#define LOG_ASYNC	0x04
65#define LOG_RDWAIT	0x08
66
67struct logsoftc {
68	int	sc_state;		/* see above for possibilities */
69	struct	selinfo sc_selp;	/* process waiting on select call */
70	int	sc_pgid;		/* process/group for async I/O */
71	uid_t	sc_siguid;		/* uid for process that set sc_pgid */
72	uid_t	sc_sigeuid;		/* euid for process that set sc_pgid */
73} logsoftc;
74
75int	log_open;			/* also used in log() */
76int	msgbufmapped;			/* is the message buffer mapped */
77struct	msgbuf *msgbufp;		/* the mapped buffer, itself. */
78struct	msgbuf *consbufp;		/* console message buffer. */
79struct file *syslogf;
80
81void filt_logrdetach(struct knote *kn);
82int filt_logread(struct knote *kn, long hint);
83
84struct filterops logread_filtops =
85	{ 1, NULL, filt_logrdetach, filt_logread};
86
87int dosendsyslog(struct proc *, const char *, size_t, int, enum uio_seg);
88
89void
90initmsgbuf(caddr_t buf, size_t bufsize)
91{
92	struct msgbuf *mbp;
93	long new_bufs;
94
95	/* Sanity-check the given size. */
96	if (bufsize < sizeof(struct msgbuf))
97		return;
98
99	mbp = msgbufp = (struct msgbuf *)buf;
100
101	new_bufs = bufsize - offsetof(struct msgbuf, msg_bufc);
102	if ((mbp->msg_magic != MSG_MAGIC) || (mbp->msg_bufs != new_bufs) ||
103	    (mbp->msg_bufr < 0) || (mbp->msg_bufr >= mbp->msg_bufs) ||
104	    (mbp->msg_bufx < 0) || (mbp->msg_bufx >= mbp->msg_bufs)) {
105		/*
106		 * If the buffer magic number is wrong, has changed
107		 * size (which shouldn't happen often), or is
108		 * internally inconsistent, initialize it.
109		 */
110
111		memset(buf, 0, bufsize);
112		mbp->msg_magic = MSG_MAGIC;
113		mbp->msg_bufs = new_bufs;
114	}
115
116	/* Always start new buffer data on a new line. */
117	if (mbp->msg_bufx > 0 && mbp->msg_bufc[mbp->msg_bufx - 1] != '\n')
118		msgbuf_putchar(msgbufp, '\n');
119
120	/* mark it as ready for use. */
121	msgbufmapped = 1;
122}
123
124void
125initconsbuf(void)
126{
127	long new_bufs;
128
129	/* Set up a buffer to collect /dev/console output */
130	consbufp = malloc(CONSBUFSIZE, M_TEMP, M_NOWAIT|M_ZERO);
131	if (consbufp) {
132		new_bufs = CONSBUFSIZE - offsetof(struct msgbuf, msg_bufc);
133		consbufp->msg_magic = MSG_MAGIC;
134		consbufp->msg_bufs = new_bufs;
135	}
136}
137
138void
139msgbuf_putchar(struct msgbuf *mbp, const char c)
140{
141	if (mbp->msg_magic != MSG_MAGIC)
142		/* Nothing we can do */
143		return;
144
145	mbp->msg_bufc[mbp->msg_bufx++] = c;
146	mbp->msg_bufl = min(mbp->msg_bufl+1, mbp->msg_bufs);
147	if (mbp->msg_bufx < 0 || mbp->msg_bufx >= mbp->msg_bufs)
148		mbp->msg_bufx = 0;
149	/* If the buffer is full, keep the most recent data. */
150	if (mbp->msg_bufr == mbp->msg_bufx) {
151		if (++mbp->msg_bufr >= mbp->msg_bufs)
152			mbp->msg_bufr = 0;
153	}
154}
155
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
165int
166logclose(dev_t dev, int flag, int mode, struct proc *p)
167{
168
169	if (syslogf)
170		FRELE(syslogf, p);
171	syslogf = NULL;
172	log_open = 0;
173	logsoftc.sc_state = 0;
174	return (0);
175}
176
177int
178logread(dev_t dev, struct uio *uio, int flag)
179{
180	struct msgbuf *mbp = msgbufp;
181	long l;
182	int s;
183	int error = 0;
184
185	s = splhigh();
186	while (mbp->msg_bufr == mbp->msg_bufx) {
187		if (flag & IO_NDELAY) {
188			splx(s);
189			return (EWOULDBLOCK);
190		}
191		logsoftc.sc_state |= LOG_RDWAIT;
192		error = tsleep(mbp, LOG_RDPRI | PCATCH,
193			       "klog", 0);
194		if (error) {
195			splx(s);
196			return (error);
197		}
198	}
199	splx(s);
200	logsoftc.sc_state &= ~LOG_RDWAIT;
201
202	while (uio->uio_resid > 0) {
203		l = mbp->msg_bufx - mbp->msg_bufr;
204		if (l < 0)
205			l = mbp->msg_bufs - mbp->msg_bufr;
206		l = min(l, uio->uio_resid);
207		if (l == 0)
208			break;
209		error = uiomovei(&mbp->msg_bufc[mbp->msg_bufr], (int)l, uio);
210		if (error)
211			break;
212		mbp->msg_bufr += l;
213		if (mbp->msg_bufr < 0 || mbp->msg_bufr >= mbp->msg_bufs)
214			mbp->msg_bufr = 0;
215	}
216	return (error);
217}
218
219int
220logpoll(dev_t dev, int events, struct proc *p)
221{
222	int revents = 0;
223	int s = splhigh();
224
225	if (events & (POLLIN | POLLRDNORM)) {
226		if (msgbufp->msg_bufr != msgbufp->msg_bufx)
227			revents |= events & (POLLIN | POLLRDNORM);
228		else
229			selrecord(p, &logsoftc.sc_selp);
230	}
231	splx(s);
232	return (revents);
233}
234
235int
236logkqfilter(dev_t dev, struct knote *kn)
237{
238	struct klist *klist;
239	int s;
240
241	switch (kn->kn_filter) {
242	case EVFILT_READ:
243		klist = &logsoftc.sc_selp.si_note;
244		kn->kn_fop = &logread_filtops;
245		break;
246	default:
247		return (EINVAL);
248	}
249
250	kn->kn_hook = (void *)msgbufp;
251
252	s = splhigh();
253	SLIST_INSERT_HEAD(klist, kn, kn_selnext);
254	splx(s);
255
256	return (0);
257}
258
259void
260filt_logrdetach(struct knote *kn)
261{
262	int s = splhigh();
263
264	SLIST_REMOVE(&logsoftc.sc_selp.si_note, kn, knote, kn_selnext);
265	splx(s);
266}
267
268int
269filt_logread(struct knote *kn, long hint)
270{
271	struct  msgbuf *p = (struct  msgbuf *)kn->kn_hook;
272
273	kn->kn_data = (int)(p->msg_bufx - p->msg_bufr);
274
275	return (p->msg_bufx != p->msg_bufr);
276}
277
278void
279logwakeup(void)
280{
281	if (!log_open)
282		return;
283	selwakeup(&logsoftc.sc_selp);
284	if (logsoftc.sc_state & LOG_ASYNC)
285		csignal(logsoftc.sc_pgid, SIGIO,
286		    logsoftc.sc_siguid, logsoftc.sc_sigeuid);
287	if (logsoftc.sc_state & LOG_RDWAIT) {
288		wakeup(msgbufp);
289		logsoftc.sc_state &= ~LOG_RDWAIT;
290	}
291}
292
293int
294logioctl(dev_t dev, u_long com, caddr_t data, int flag, struct proc *p)
295{
296	struct file *fp;
297	long l;
298	int error, s;
299
300	switch (com) {
301
302	/* return number of characters immediately available */
303	case FIONREAD:
304		s = splhigh();
305		l = msgbufp->msg_bufx - msgbufp->msg_bufr;
306		splx(s);
307		if (l < 0)
308			l += msgbufp->msg_bufs;
309		*(int *)data = l;
310		break;
311
312	case FIONBIO:
313		break;
314
315	case FIOASYNC:
316		if (*(int *)data)
317			logsoftc.sc_state |= LOG_ASYNC;
318		else
319			logsoftc.sc_state &= ~LOG_ASYNC;
320		break;
321
322	case TIOCSPGRP:
323		logsoftc.sc_pgid = *(int *)data;
324		logsoftc.sc_siguid = p->p_ucred->cr_ruid;
325		logsoftc.sc_sigeuid = p->p_ucred->cr_uid;
326		break;
327
328	case TIOCGPGRP:
329		*(int *)data = logsoftc.sc_pgid;
330		break;
331
332	case LIOCSFD:
333		if ((error = suser(p, 0)) != 0)
334			return (error);
335		if ((error = getsock(p, *(int *)data, &fp)) != 0)
336			return (error);
337		if (syslogf)
338			FRELE(syslogf, p);
339		syslogf = fp;
340		break;
341
342	default:
343		return (ENOTTY);
344	}
345	return (0);
346}
347
348int
349sys_sendsyslog(struct proc *p, void *v, register_t *retval)
350{
351	struct sys_sendsyslog_args /* {
352		syscallarg(const void *) buf;
353		syscallarg(size_t) nbyte;
354	} */ *uap = v;
355	struct sys_sendsyslog2_args oap;
356
357	SCARG(&oap, buf) = SCARG(uap, buf);
358	SCARG(&oap, nbyte) = SCARG(uap, nbyte);
359	SCARG(&oap, flags) = 0;
360	return sys_sendsyslog2(p, &oap, retval);
361}
362
363int
364sys_sendsyslog2(struct proc *p, void *v, register_t *retval)
365{
366	struct sys_sendsyslog2_args /* {
367		syscallarg(const void *) buf;
368		syscallarg(size_t) nbyte;
369		syscallarg(int) flags;
370	} */ *uap = v;
371	int error;
372#ifndef SMALL_KERNEL
373	static int dropped_count, orig_error;
374	int len;
375	char buf[64];
376
377	if (dropped_count) {
378		len = snprintf(buf, sizeof(buf),
379		    "<%d>sendsyslog: dropped %d message%s, error %d",
380		    LOG_KERN|LOG_WARNING, dropped_count,
381		    dropped_count == 1 ? "" : "s", orig_error);
382		error = dosendsyslog(p, buf, MIN((size_t)len, sizeof(buf) - 1),
383		    SCARG(uap, flags), UIO_SYSSPACE);
384		if (error) {
385			dropped_count++;
386			return (error);
387		}
388		dropped_count = 0;
389	}
390#endif
391	error = dosendsyslog(p, SCARG(uap, buf), SCARG(uap, nbyte),
392	    SCARG(uap, flags), UIO_USERSPACE);
393#ifndef SMALL_KERNEL
394	if (error && error != ENOTCONN) {
395		dropped_count++;
396		orig_error = error;
397	}
398#endif
399	return (error);
400}
401
402int
403dosendsyslog(struct proc *p, const char *buf, size_t nbyte, int flags,
404    enum uio_seg sflg)
405{
406#ifdef KTRACE
407	struct iovec *ktriov = NULL;
408	int iovlen;
409#endif
410	extern struct tty *constty;
411	struct iovec aiov;
412	struct uio auio;
413	struct file *f;
414	size_t len;
415	int error;
416
417	if (syslogf == NULL) {
418		if (constty && (flags & LOG_CONS)) {
419			int i;
420
421			/* Skip syslog prefix */
422			if (nbyte >= 4 && buf[0] == '<' &&
423			    buf[3] == '>') {
424				buf += 4;
425				nbyte -= 4;
426			}
427			for (i = 0; i < nbyte; i++)
428				tputchar(buf[i], constty);
429			tputchar('\n', constty);
430		}
431		return (ENOTCONN);
432	}
433	f = syslogf;
434	FREF(f);
435
436	aiov.iov_base = (char *)buf;
437	aiov.iov_len = nbyte;
438	auio.uio_iov = &aiov;
439	auio.uio_iovcnt = 1;
440	auio.uio_segflg = sflg;
441	auio.uio_rw = UIO_WRITE;
442	auio.uio_procp = p;
443	auio.uio_offset = 0;
444	auio.uio_resid = aiov.iov_len;
445#ifdef KTRACE
446	if (KTRPOINT(p, KTR_GENIO)) {
447		ktriov = mallocarray(auio.uio_iovcnt, sizeof(struct iovec),
448		    M_TEMP, M_WAITOK);
449		iovlen = auio.uio_iovcnt * sizeof (struct iovec);
450
451		memcpy(ktriov, auio.uio_iov, iovlen);
452	}
453#endif
454
455	len = auio.uio_resid;
456	error = sosend(f->f_data, NULL, &auio, NULL, NULL, 0);
457	if (error == 0)
458		len -= auio.uio_resid;
459
460#ifdef KTRACE
461	if (ktriov != NULL) {
462		if (error == 0)
463			ktrgenio(p, -1, UIO_WRITE, ktriov, len);
464		free(ktriov, M_TEMP, iovlen);
465	}
466#endif
467	FRELE(f, p);
468	return error;
469}
470