kvm.c revision 183986 
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 183986 2008-10-17 20:11:28Z 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 = calloc(1, sizeof(*kd))) == NULL) {
248		(void)strlcpy(errout, strerror(errno), _POSIX2_LINE_MAX);
249		return (0);
250	}
251	kd->program = 0;
252	return (_kvm_open(kd, uf, mf, flag, errout));
253}
254
255kvm_t *
256kvm_open(uf, mf, sf, flag, errstr)
257	const char *uf;
258	const char *mf;
259	const char *sf __unused;
260	int flag;
261	const char *errstr;
262{
263	kvm_t *kd;
264
265	if ((kd = calloc(1, sizeof(*kd))) == NULL) {
266		if (errstr != NULL)
267			(void)fprintf(stderr, "%s: %s\n",
268				      errstr, strerror(errno));
269		return (0);
270	}
271	kd->program = errstr;
272	return (_kvm_open(kd, uf, mf, flag, NULL));
273}
274
275int
276kvm_close(kd)
277	kvm_t *kd;
278{
279	int error = 0;
280
281	if (kd->pmfd >= 0)
282		error |= close(kd->pmfd);
283	if (kd->vmfd >= 0)
284		error |= close(kd->vmfd);
285	if (kd->nlfd >= 0)
286		error |= close(kd->nlfd);
287	if (kd->vmst)
288		_kvm_freevtop(kd);
289	if (kd->procbase != 0)
290		free((void *)kd->procbase);
291	if (kd->argbuf != 0)
292		free((void *) kd->argbuf);
293	if (kd->argspc != 0)
294		free((void *) kd->argspc);
295	if (kd->argv != 0)
296		free((void *)kd->argv);
297	free((void *)kd);
298
299	return (0);
300}
301
302int
303kvm_nlist(kd, nl)
304	kvm_t *kd;
305	struct nlist *nl;
306{
307	struct nlist *p;
308	int nvalid;
309	struct kld_sym_lookup lookup;
310	int error;
311
312	/*
313	 * If we can't use the kld symbol lookup, revert to the
314	 * slow library call.
315	 */
316	if (!ISALIVE(kd))
317		return (__fdnlist(kd->nlfd, nl));
318
319	/*
320	 * We can use the kld lookup syscall.  Go through each nlist entry
321	 * and look it up with a kldsym(2) syscall.
322	 */
323	nvalid = 0;
324	for (p = nl; p->n_name && p->n_name[0]; ++p) {
325		lookup.version = sizeof(lookup);
326		lookup.symname = p->n_name;
327		lookup.symvalue = 0;
328		lookup.symsize = 0;
329
330		if (lookup.symname[0] == '_')
331			lookup.symname++;
332
333		if (kldsym(0, KLDSYM_LOOKUP, &lookup) != -1) {
334			p->n_type = N_TEXT;
335			p->n_other = 0;
336			p->n_desc = 0;
337			p->n_value = lookup.symvalue;
338			++nvalid;
339			/* lookup.symsize */
340		}
341	}
342	/*
343	 * Return the number of entries that weren't found. If they exist,
344	 * also fill internal error buffer.
345	 */
346	error = ((p - nl) - nvalid);
347	if (error)
348		_kvm_syserr(kd, kd->program, "kvm_nlist");
349	return (error);
350}
351
352ssize_t
353kvm_read(kd, kva, buf, len)
354	kvm_t *kd;
355	u_long kva;
356	void *buf;
357	size_t len;
358{
359	int cc;
360	char *cp;
361
362	if (ISALIVE(kd)) {
363		/*
364		 * We're using /dev/kmem.  Just read straight from the
365		 * device and let the active kernel do the address translation.
366		 */
367		errno = 0;
368		if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
369			_kvm_err(kd, 0, "invalid address (%x)", kva);
370			return (-1);
371		}
372		cc = read(kd->vmfd, buf, len);
373		if (cc < 0) {
374			_kvm_syserr(kd, 0, "kvm_read");
375			return (-1);
376		} else if (cc < len)
377			_kvm_err(kd, kd->program, "short read");
378		return (cc);
379	} else {
380		cp = buf;
381		while (len > 0) {
382			off_t pa;
383
384			cc = _kvm_kvatop(kd, kva, &pa);
385			if (cc == 0)
386				return (-1);
387			if (cc > len)
388				cc = len;
389			errno = 0;
390			if (lseek(kd->pmfd, pa, 0) == -1 && errno != 0) {
391				_kvm_syserr(kd, 0, _PATH_MEM);
392				break;
393			}
394			cc = read(kd->pmfd, cp, cc);
395			if (cc < 0) {
396				_kvm_syserr(kd, kd->program, "kvm_read");
397				break;
398			}
399			/*
400			 * If kvm_kvatop returns a bogus value or our core
401			 * file is truncated, we might wind up seeking beyond
402			 * the end of the core file in which case the read will
403			 * return 0 (EOF).
404			 */
405			if (cc == 0)
406				break;
407			cp += cc;
408			kva += cc;
409			len -= cc;
410		}
411		return (cp - (char *)buf);
412	}
413	/* NOTREACHED */
414}
415
416ssize_t
417kvm_write(kd, kva, buf, len)
418	kvm_t *kd;
419	u_long kva;
420	const void *buf;
421	size_t len;
422{
423	int cc;
424
425	if (ISALIVE(kd)) {
426		/*
427		 * Just like kvm_read, only we write.
428		 */
429		errno = 0;
430		if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
431			_kvm_err(kd, 0, "invalid address (%x)", kva);
432			return (-1);
433		}
434		cc = write(kd->vmfd, buf, len);
435		if (cc < 0) {
436			_kvm_syserr(kd, 0, "kvm_write");
437			return (-1);
438		} else if (cc < len)
439			_kvm_err(kd, kd->program, "short write");
440		return (cc);
441	} else {
442		_kvm_err(kd, kd->program,
443		    "kvm_write not implemented for dead kernels");
444		return (-1);
445	}
446	/* NOTREACHED */
447}
448