subr_log.c revision 1.33 
1/*	$OpenBSD: subr_log.c,v 1.33 2015/11/24 23:59:22 deraadt 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
156/*ARGSUSED*/
157int
158logopen(dev_t dev, int flags, int mode, struct proc *p)
159{
160	if (log_open)
161		return (EBUSY);
162	log_open = 1;
163	return (0);
164}
165
166/*ARGSUSED*/
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
179/*ARGSUSED*/
180int
181logread(dev_t dev, struct uio *uio, int flag)
182{
183	struct msgbuf *mbp = msgbufp;
184	long l;
185	int s;
186	int error = 0;
187
188	s = splhigh();
189	while (mbp->msg_bufr == mbp->msg_bufx) {
190		if (flag & IO_NDELAY) {
191			splx(s);
192			return (EWOULDBLOCK);
193		}
194		logsoftc.sc_state |= LOG_RDWAIT;
195		error = tsleep(mbp, LOG_RDPRI | PCATCH,
196			       "klog", 0);
197		if (error) {
198			splx(s);
199			return (error);
200		}
201	}
202	splx(s);
203	logsoftc.sc_state &= ~LOG_RDWAIT;
204
205	while (uio->uio_resid > 0) {
206		l = mbp->msg_bufx - mbp->msg_bufr;
207		if (l < 0)
208			l = mbp->msg_bufs - mbp->msg_bufr;
209		l = min(l, uio->uio_resid);
210		if (l == 0)
211			break;
212		error = uiomovei(&mbp->msg_bufc[mbp->msg_bufr], (int)l, uio);
213		if (error)
214			break;
215		mbp->msg_bufr += l;
216		if (mbp->msg_bufr < 0 || mbp->msg_bufr >= mbp->msg_bufs)
217			mbp->msg_bufr = 0;
218	}
219	return (error);
220}
221
222/*ARGSUSED*/
223int
224logpoll(dev_t dev, int events, struct proc *p)
225{
226	int revents = 0;
227	int s = splhigh();
228
229	if (events & (POLLIN | POLLRDNORM)) {
230		if (msgbufp->msg_bufr != msgbufp->msg_bufx)
231			revents |= events & (POLLIN | POLLRDNORM);
232		else
233			selrecord(p, &logsoftc.sc_selp);
234	}
235	splx(s);
236	return (revents);
237}
238
239int
240logkqfilter(dev_t dev, struct knote *kn)
241{
242	struct klist *klist;
243	int s;
244
245	switch (kn->kn_filter) {
246	case EVFILT_READ:
247		klist = &logsoftc.sc_selp.si_note;
248		kn->kn_fop = &logread_filtops;
249		break;
250	default:
251		return (EINVAL);
252	}
253
254	kn->kn_hook = (void *)msgbufp;
255
256	s = splhigh();
257	SLIST_INSERT_HEAD(klist, kn, kn_selnext);
258	splx(s);
259
260	return (0);
261}
262
263void
264filt_logrdetach(struct knote *kn)
265{
266	int s = splhigh();
267
268	SLIST_REMOVE(&logsoftc.sc_selp.si_note, kn, knote, kn_selnext);
269	splx(s);
270}
271
272int
273filt_logread(struct knote *kn, long hint)
274{
275	struct  msgbuf *p = (struct  msgbuf *)kn->kn_hook;
276
277	kn->kn_data = (int)(p->msg_bufx - p->msg_bufr);
278
279	return (p->msg_bufx != p->msg_bufr);
280}
281
282void
283logwakeup(void)
284{
285	if (!log_open)
286		return;
287	selwakeup(&logsoftc.sc_selp);
288	if (logsoftc.sc_state & LOG_ASYNC)
289		csignal(logsoftc.sc_pgid, SIGIO,
290		    logsoftc.sc_siguid, logsoftc.sc_sigeuid);
291	if (logsoftc.sc_state & LOG_RDWAIT) {
292		wakeup(msgbufp);
293		logsoftc.sc_state &= ~LOG_RDWAIT;
294	}
295}
296
297/*ARGSUSED*/
298int
299logioctl(dev_t dev, u_long com, caddr_t data, int flag, struct proc *p)
300{
301	struct file *fp;
302	long l;
303	int error, s;
304
305	switch (com) {
306
307	/* return number of characters immediately available */
308	case FIONREAD:
309		s = splhigh();
310		l = msgbufp->msg_bufx - msgbufp->msg_bufr;
311		splx(s);
312		if (l < 0)
313			l += msgbufp->msg_bufs;
314		*(int *)data = l;
315		break;
316
317	case FIONBIO:
318		break;
319
320	case FIOASYNC:
321		if (*(int *)data)
322			logsoftc.sc_state |= LOG_ASYNC;
323		else
324			logsoftc.sc_state &= ~LOG_ASYNC;
325		break;
326
327	case TIOCSPGRP:
328		logsoftc.sc_pgid = *(int *)data;
329		logsoftc.sc_siguid = p->p_ucred->cr_ruid;
330		logsoftc.sc_sigeuid = p->p_ucred->cr_uid;
331		break;
332
333	case TIOCGPGRP:
334		*(int *)data = logsoftc.sc_pgid;
335		break;
336
337	case LIOCSFD:
338		if ((error = suser(p, 0)) != 0)
339			return (error);
340		if ((error = getsock(p, *(int *)data, &fp)) != 0)
341			return (error);
342		if (syslogf)
343			FRELE(syslogf, p);
344		syslogf = fp;
345		break;
346
347	default:
348		return (ENOTTY);
349	}
350	return (0);
351}
352
353int
354sys_sendsyslog(struct proc *p, void *v, register_t *retval)
355{
356	struct sys_sendsyslog_args /* {
357		syscallarg(const void *) buf;
358		syscallarg(size_t) nbyte;
359	} */ *uap = v;
360	struct sys_sendsyslog2_args oap;
361
362	SCARG(&oap, buf) = SCARG(uap, buf);
363	SCARG(&oap, nbyte) = SCARG(uap, nbyte);
364	SCARG(&oap, flags) = 0;
365	return sys_sendsyslog2(p, &oap, retval);
366}
367
368int
369sys_sendsyslog2(struct proc *p, void *v, register_t *retval)
370{
371	struct sys_sendsyslog2_args /* {
372		syscallarg(const void *) buf;
373		syscallarg(size_t) nbyte;
374		syscallarg(int) flags;
375	} */ *uap = v;
376	int error;
377#ifndef SMALL_KERNEL
378	static int dropped_count, orig_error;
379	int len;
380	char buf[64];
381
382	if (dropped_count) {
383		len = snprintf(buf, sizeof(buf),
384		    "<%d>sendsyslog: dropped %d message%s, error %d",
385		    LOG_KERN|LOG_WARNING, dropped_count,
386		    dropped_count == 1 ? "" : "s", orig_error);
387		error = dosendsyslog(p, buf, MIN((size_t)len, sizeof(buf) - 1),
388		    SCARG(uap, flags), UIO_SYSSPACE);
389		if (error) {
390			dropped_count++;
391			return (error);
392		}
393		dropped_count = 0;
394	}
395#endif
396	error = dosendsyslog(p, SCARG(uap, buf), SCARG(uap, nbyte),
397	    SCARG(uap, flags), UIO_USERSPACE);
398#ifndef SMALL_KERNEL
399	if (error && error != ENOTCONN) {
400		dropped_count++;
401		orig_error = error;
402	}
403#endif
404	return (error);
405}
406
407int
408dosendsyslog(struct proc *p, const char *buf, size_t nbyte, int flags,
409    enum uio_seg sflg)
410{
411#ifdef KTRACE
412	struct iovec *ktriov = NULL;
413	int iovlen;
414#endif
415	extern struct tty *constty;
416	struct iovec aiov;
417	struct uio auio;
418	struct file *f;
419	size_t len;
420	int error;
421
422	if (syslogf == NULL) {
423		if (constty && (flags & LOG_CONS)) {
424			int i;
425
426			/* Skip syslog prefix */
427			if (nbyte >= 4 && buf[0] == '<' &&
428			    buf[3] == '>') {
429				buf += 4;
430				nbyte -= 4;
431			}
432			for (i = 0; i < nbyte; i++)
433				tputchar(buf[i], constty);
434			tputchar('\n', constty);
435		}
436		return (ENOTCONN);
437	}
438	f = syslogf;
439	FREF(f);
440
441	aiov.iov_base = (char *)buf;
442	aiov.iov_len = nbyte;
443	auio.uio_iov = &aiov;
444	auio.uio_iovcnt = 1;
445	auio.uio_segflg = sflg;
446	auio.uio_rw = UIO_WRITE;
447	auio.uio_procp = p;
448	auio.uio_offset = 0;
449	auio.uio_resid = aiov.iov_len;
450#ifdef KTRACE
451	if (KTRPOINT(p, KTR_GENIO)) {
452		ktriov = mallocarray(auio.uio_iovcnt, sizeof(struct iovec),
453		    M_TEMP, M_WAITOK);
454		iovlen = auio.uio_iovcnt * sizeof (struct iovec);
455
456		memcpy(ktriov, auio.uio_iov, iovlen);
457	}
458#endif
459
460	len = auio.uio_resid;
461	error = sosend(f->f_data, NULL, &auio, NULL, NULL, 0);
462	if (error == 0)
463		len -= auio.uio_resid;
464
465#ifdef KTRACE
466	if (ktriov != NULL) {
467		if (error == 0)
468			ktrgenio(p, -1, UIO_WRITE, ktriov, len);
469		free(ktriov, M_TEMP, iovlen);
470	}
471#endif
472	FRELE(f, p);
473	return error;
474}
475