kvm.c revision 175243 
1/*-
2 * Copyright (c) 1989, 1992, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * This code is derived from software developed by the Computer Systems
6 * Engineering group at Lawrence Berkeley Laboratory under DARPA contract
7 * BG 91-66 and contributed to Berkeley.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 *    notice, this list of conditions and the following disclaimer in the
16 *    documentation and/or other materials provided with the distribution.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#include <sys/cdefs.h>
35__FBSDID("$FreeBSD: head/lib/libkvm/kvm.c 175243 2008-01-12 00:54:47Z delphij $");
36
37#if defined(LIBC_SCCS) && !defined(lint)
38#if 0
39static char sccsid[] = "@(#)kvm.c	8.2 (Berkeley) 2/13/94";
40#endif
41#endif /* LIBC_SCCS and not lint */
42
43#include <sys/param.h>
44#include <sys/user.h>
45#include <sys/proc.h>
46#include <sys/ioctl.h>
47#include <sys/stat.h>
48#include <sys/sysctl.h>
49#include <sys/linker.h>
50
51#include <vm/vm.h>
52#include <vm/vm_param.h>
53
54#include <machine/vmparam.h>
55
56#include <ctype.h>
57#include <fcntl.h>
58#include <kvm.h>
59#include <limits.h>
60#include <nlist.h>
61#include <paths.h>
62#include <stdio.h>
63#include <stdlib.h>
64#include <string.h>
65#include <unistd.h>
66
67#include "kvm_private.h"
68
69/* from src/lib/libc/gen/nlist.c */
70int __fdnlist(int, struct nlist *);
71
72char *
73kvm_geterr(kd)
74	kvm_t *kd;
75{
76	return (kd->errbuf);
77}
78
79#include <stdarg.h>
80
81/*
82 * Report an error using printf style arguments.  "program" is kd->program
83 * on hard errors, and 0 on soft errors, so that under sun error emulation,
84 * only hard errors are printed out (otherwise, programs like gdb will
85 * generate tons of error messages when trying to access bogus pointers).
86 */
87void
88_kvm_err(kvm_t *kd, const char *program, const char *fmt, ...)
89{
90	va_list ap;
91
92	va_start(ap, fmt);
93	if (program != NULL) {
94		(void)fprintf(stderr, "%s: ", program);
95		(void)vfprintf(stderr, fmt, ap);
96		(void)fputc('\n', stderr);
97	} else
98		(void)vsnprintf(kd->errbuf,
99		    sizeof(kd->errbuf), (char *)fmt, ap);
100
101	va_end(ap);
102}
103
104void
105_kvm_syserr(kvm_t *kd, const char *program, const char *fmt, ...)
106{
107	va_list ap;
108	int n;
109
110	va_start(ap, fmt);
111	if (program != NULL) {
112		(void)fprintf(stderr, "%s: ", program);
113		(void)vfprintf(stderr, fmt, ap);
114		(void)fprintf(stderr, ": %s\n", strerror(errno));
115	} else {
116		char *cp = kd->errbuf;
117
118		(void)vsnprintf(cp, sizeof(kd->errbuf), (char *)fmt, ap);
119		n = strlen(cp);
120		(void)snprintf(&cp[n], sizeof(kd->errbuf) - n, ": %s",
121		    strerror(errno));
122	}
123	va_end(ap);
124}
125
126void *
127_kvm_malloc(kd, n)
128	kvm_t *kd;
129	size_t n;
130{
131	void *p;
132
133	if ((p = calloc(n, sizeof(char))) == NULL)
134		_kvm_err(kd, kd->program, "can't allocate %u bytes: %s",
135			 n, strerror(errno));
136	return (p);
137}
138
139static kvm_t *
140_kvm_open(kd, uf, mf, flag, errout)
141	kvm_t *kd;
142	const char *uf;
143	const char *mf;
144	int flag;
145	char *errout;
146{
147	struct stat st;
148
149	kd->vmfd = -1;
150	kd->pmfd = -1;
151	kd->nlfd = -1;
152	kd->vmst = 0;
153	kd->procbase = 0;
154	kd->argspc = 0;
155	kd->argv = 0;
156
157	if (uf == 0)
158		uf = getbootfile();
159	else if (strlen(uf) >= MAXPATHLEN) {
160		_kvm_err(kd, kd->program, "exec file name too long");
161		goto failed;
162	}
163	if (flag & ~O_RDWR) {
164		_kvm_err(kd, kd->program, "bad flags arg");
165		goto failed;
166	}
167	if (mf == 0)
168		mf = _PATH_MEM;
169
170	if ((kd->pmfd = open(mf, flag, 0)) < 0) {
171		_kvm_syserr(kd, kd->program, "%s", mf);
172		goto failed;
173	}
174	if (fstat(kd->pmfd, &st) < 0) {
175		_kvm_syserr(kd, kd->program, "%s", mf);
176		goto failed;
177	}
178	if (S_ISREG(st.st_mode) && st.st_size <= 0) {
179		errno = EINVAL;
180		_kvm_syserr(kd, kd->program, "empty file");
181		goto failed;
182	}
183	if (fcntl(kd->pmfd, F_SETFD, FD_CLOEXEC) < 0) {
184		_kvm_syserr(kd, kd->program, "%s", mf);
185		goto failed;
186	}
187	if (S_ISCHR(st.st_mode)) {
188		/*
189		 * If this is a character special device, then check that
190		 * it's /dev/mem.  If so, open kmem too.  (Maybe we should
191		 * make it work for either /dev/mem or /dev/kmem -- in either
192		 * case you're working with a live kernel.)
193		 */
194		if (strcmp(mf, _PATH_DEVNULL) == 0) {
195			kd->vmfd = open(_PATH_DEVNULL, O_RDONLY);
196			return (kd);
197		} else if (strcmp(mf, _PATH_MEM) == 0) {
198			if ((kd->vmfd = open(_PATH_KMEM, flag)) < 0) {
199				_kvm_syserr(kd, kd->program, "%s", _PATH_KMEM);
200				goto failed;
201			}
202			if (fcntl(kd->vmfd, F_SETFD, FD_CLOEXEC) < 0) {
203				_kvm_syserr(kd, kd->program, "%s", _PATH_KMEM);
204				goto failed;
205			}
206			return (kd);
207		}
208	}
209	/*
210	 * This is a crash dump.
211	 * Initialize the virtual address translation machinery,
212	 * but first setup the namelist fd.
213	 */
214	if ((kd->nlfd = open(uf, O_RDONLY, 0)) < 0) {
215		_kvm_syserr(kd, kd->program, "%s", uf);
216		goto failed;
217	}
218	if (fcntl(kd->nlfd, F_SETFD, FD_CLOEXEC) < 0) {
219		_kvm_syserr(kd, kd->program, "%s", uf);
220		goto failed;
221	}
222	if (strncmp(mf, _PATH_FWMEM, strlen(_PATH_FWMEM)) == 0)
223		kd->rawdump = 1;
224	if (_kvm_initvtop(kd) < 0)
225		goto failed;
226	return (kd);
227failed:
228	/*
229	 * Copy out the error if doing sane error semantics.
230	 */
231	if (errout != 0)
232		strlcpy(errout, kd->errbuf, _POSIX2_LINE_MAX);
233	(void)kvm_close(kd);
234	return (0);
235}
236
237kvm_t *
238kvm_openfiles(uf, mf, sf, flag, errout)
239	const char *uf;
240	const char *mf;
241	const char *sf __unused;
242	int flag;
243	char *errout;
244{
245	kvm_t *kd;
246
247	if ((kd = malloc(sizeof(*kd))) == NULL) {
248		(void)strlcpy(errout, strerror(errno), _POSIX2_LINE_MAX);
249		return (0);
250	}
251	memset(kd, 0, sizeof(*kd));
252	kd->program = 0;
253	return (_kvm_open(kd, uf, mf, flag, errout));
254}
255
256kvm_t *
257kvm_open(uf, mf, sf, flag, errstr)
258	const char *uf;
259	const char *mf;
260	const char *sf __unused;
261	int flag;
262	const char *errstr;
263{
264	kvm_t *kd;
265
266	if ((kd = malloc(sizeof(*kd))) == NULL) {
267		if (errstr != NULL)
268			(void)fprintf(stderr, "%s: %s\n",
269				      errstr, strerror(errno));
270		return (0);
271	}
272	memset(kd, 0, sizeof(*kd));
273	kd->program = errstr;
274	return (_kvm_open(kd, uf, mf, flag, NULL));
275}
276
277int
278kvm_close(kd)
279	kvm_t *kd;
280{
281	int error = 0;
282
283	if (kd->pmfd >= 0)
284		error |= close(kd->pmfd);
285	if (kd->vmfd >= 0)
286		error |= close(kd->vmfd);
287	if (kd->nlfd >= 0)
288		error |= close(kd->nlfd);
289	if (kd->vmst)
290		_kvm_freevtop(kd);
291	if (kd->procbase != 0)
292		free((void *)kd->procbase);
293	if (kd->argbuf != 0)
294		free((void *) kd->argbuf);
295	if (kd->argspc != 0)
296		free((void *) kd->argspc);
297	if (kd->argv != 0)
298		free((void *)kd->argv);
299	free((void *)kd);
300
301	return (0);
302}
303
304int
305kvm_nlist(kd, nl)
306	kvm_t *kd;
307	struct nlist *nl;
308{
309	struct nlist *p;
310	int nvalid;
311	struct kld_sym_lookup lookup;
312	int error;
313
314	/*
315	 * If we can't use the kld symbol lookup, revert to the
316	 * slow library call.
317	 */
318	if (!ISALIVE(kd))
319		return (__fdnlist(kd->nlfd, nl));
320
321	/*
322	 * We can use the kld lookup syscall.  Go through each nlist entry
323	 * and look it up with a kldsym(2) syscall.
324	 */
325	nvalid = 0;
326	for (p = nl; p->n_name && p->n_name[0]; ++p) {
327		lookup.version = sizeof(lookup);
328		lookup.symname = p->n_name;
329		lookup.symvalue = 0;
330		lookup.symsize = 0;
331
332		if (lookup.symname[0] == '_')
333			lookup.symname++;
334
335		if (kldsym(0, KLDSYM_LOOKUP, &lookup) != -1) {
336			p->n_type = N_TEXT;
337			p->n_other = 0;
338			p->n_desc = 0;
339			p->n_value = lookup.symvalue;
340			++nvalid;
341			/* lookup.symsize */
342		}
343	}
344	/*
345	 * Return the number of entries that weren't found. If they exist,
346	 * also fill internal error buffer.
347	 */
348	error = ((p - nl) - nvalid);
349	if (error)
350		_kvm_syserr(kd, kd->program, "kvm_nlist");
351	return (error);
352}
353
354ssize_t
355kvm_read(kd, kva, buf, len)
356	kvm_t *kd;
357	u_long kva;
358	void *buf;
359	size_t len;
360{
361	int cc;
362	char *cp;
363
364	if (ISALIVE(kd)) {
365		/*
366		 * We're using /dev/kmem.  Just read straight from the
367		 * device and let the active kernel do the address translation.
368		 */
369		errno = 0;
370		if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
371			_kvm_err(kd, 0, "invalid address (%x)", kva);
372			return (-1);
373		}
374		cc = read(kd->vmfd, buf, len);
375		if (cc < 0) {
376			_kvm_syserr(kd, 0, "kvm_read");
377			return (-1);
378		} else if (cc < len)
379			_kvm_err(kd, kd->program, "short read");
380		return (cc);
381	} else {
382		cp = buf;
383		while (len > 0) {
384			off_t pa;
385
386			cc = _kvm_kvatop(kd, kva, &pa);
387			if (cc == 0)
388				return (-1);
389			if (cc > len)
390				cc = len;
391			errno = 0;
392			if (lseek(kd->pmfd, pa, 0) == -1 && errno != 0) {
393				_kvm_syserr(kd, 0, _PATH_MEM);
394				break;
395			}
396			cc = read(kd->pmfd, cp, cc);
397			if (cc < 0) {
398				_kvm_syserr(kd, kd->program, "kvm_read");
399				break;
400			}
401			/*
402			 * If kvm_kvatop returns a bogus value or our core
403			 * file is truncated, we might wind up seeking beyond
404			 * the end of the core file in which case the read will
405			 * return 0 (EOF).
406			 */
407			if (cc == 0)
408				break;
409			cp += cc;
410			kva += cc;
411			len -= cc;
412		}
413		return (cp - (char *)buf);
414	}
415	/* NOTREACHED */
416}
417
418ssize_t
419kvm_write(kd, kva, buf, len)
420	kvm_t *kd;
421	u_long kva;
422	const void *buf;
423	size_t len;
424{
425	int cc;
426
427	if (ISALIVE(kd)) {
428		/*
429		 * Just like kvm_read, only we write.
430		 */
431		errno = 0;
432		if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
433			_kvm_err(kd, 0, "invalid address (%x)", kva);
434			return (-1);
435		}
436		cc = write(kd->vmfd, buf, len);
437		if (cc < 0) {
438			_kvm_syserr(kd, 0, "kvm_write");
439			return (-1);
440		} else if (cc < len)
441			_kvm_err(kd, kd->program, "short write");
442		return (cc);
443	} else {
444		_kvm_err(kd, kd->program,
445		    "kvm_write not implemented for dead kernels");
446		return (-1);
447	}
448	/* NOTREACHED */
449}
450