kvm.c revision 154404 
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 * 3. All advertising materials mentioning features or use of this software
18 *    must display the following acknowledgement:
19 *	This product includes software developed by the University of
20 *	California, Berkeley and its contributors.
21 * 4. Neither the name of the University nor the names of its contributors
22 *    may be used to endorse or promote products derived from this software
23 *    without specific prior written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * SUCH DAMAGE.
36 */
37
38#include <sys/cdefs.h>
39__FBSDID("$FreeBSD: head/lib/libkvm/kvm.c 154404 2006-01-15 20:30:13Z csjp $");
40
41#if defined(LIBC_SCCS) && !defined(lint)
42#if 0
43static char sccsid[] = "@(#)kvm.c	8.2 (Berkeley) 2/13/94";
44#endif
45#endif /* LIBC_SCCS and not lint */
46
47#include <sys/param.h>
48#include <sys/user.h>
49#include <sys/proc.h>
50#include <sys/ioctl.h>
51#include <sys/stat.h>
52#include <sys/sysctl.h>
53#include <sys/linker.h>
54
55#include <vm/vm.h>
56#include <vm/vm_param.h>
57
58#include <machine/vmparam.h>
59
60#include <ctype.h>
61#include <fcntl.h>
62#include <kvm.h>
63#include <limits.h>
64#include <nlist.h>
65#include <paths.h>
66#include <stdio.h>
67#include <stdlib.h>
68#include <string.h>
69#include <unistd.h>
70
71#include "kvm_private.h"
72
73/* from src/lib/libc/gen/nlist.c */
74int __fdnlist(int, struct nlist *);
75
76char *
77kvm_geterr(kd)
78	kvm_t *kd;
79{
80	return (kd->errbuf);
81}
82
83#include <stdarg.h>
84
85/*
86 * Report an error using printf style arguments.  "program" is kd->program
87 * on hard errors, and 0 on soft errors, so that under sun error emulation,
88 * only hard errors are printed out (otherwise, programs like gdb will
89 * generate tons of error messages when trying to access bogus pointers).
90 */
91void
92_kvm_err(kvm_t *kd, const char *program, const char *fmt, ...)
93{
94	va_list ap;
95
96	va_start(ap, fmt);
97	if (program != NULL) {
98		(void)fprintf(stderr, "%s: ", program);
99		(void)vfprintf(stderr, fmt, ap);
100		(void)fputc('\n', stderr);
101	} else
102		(void)vsnprintf(kd->errbuf,
103		    sizeof(kd->errbuf), (char *)fmt, ap);
104
105	va_end(ap);
106}
107
108void
109_kvm_syserr(kvm_t *kd, const char *program, const char *fmt, ...)
110{
111	va_list ap;
112	int n;
113
114	va_start(ap, fmt);
115	if (program != NULL) {
116		(void)fprintf(stderr, "%s: ", program);
117		(void)vfprintf(stderr, fmt, ap);
118		(void)fprintf(stderr, ": %s\n", strerror(errno));
119	} else {
120		char *cp = kd->errbuf;
121
122		(void)vsnprintf(cp, sizeof(kd->errbuf), (char *)fmt, ap);
123		n = strlen(cp);
124		(void)snprintf(&cp[n], sizeof(kd->errbuf) - n, ": %s",
125		    strerror(errno));
126	}
127	va_end(ap);
128}
129
130void *
131_kvm_malloc(kd, n)
132	kvm_t *kd;
133	size_t n;
134{
135	void *p;
136
137	if ((p = calloc(n, sizeof(char))) == NULL)
138		_kvm_err(kd, kd->program, "can't allocate %u bytes: %s",
139			 n, strerror(errno));
140	return (p);
141}
142
143static kvm_t *
144_kvm_open(kd, uf, mf, flag, errout)
145	kvm_t *kd;
146	const char *uf;
147	const char *mf;
148	int flag;
149	char *errout;
150{
151	struct stat st;
152
153	kd->vmfd = -1;
154	kd->pmfd = -1;
155	kd->nlfd = -1;
156	kd->vmst = 0;
157	kd->procbase = 0;
158	kd->argspc = 0;
159	kd->argv = 0;
160
161	if (uf == 0)
162		uf = getbootfile();
163	else if (strlen(uf) >= MAXPATHLEN) {
164		_kvm_err(kd, kd->program, "exec file name too long");
165		goto failed;
166	}
167	if (flag & ~O_RDWR) {
168		_kvm_err(kd, kd->program, "bad flags arg");
169		goto failed;
170	}
171	if (mf == 0)
172		mf = _PATH_MEM;
173
174	if ((kd->pmfd = open(mf, flag, 0)) < 0) {
175		_kvm_syserr(kd, kd->program, "%s", mf);
176		goto failed;
177	}
178	if (fstat(kd->pmfd, &st) < 0) {
179		_kvm_syserr(kd, kd->program, "%s", mf);
180		goto failed;
181	}
182	if (S_ISREG(st.st_mode) && st.st_size <= 0) {
183		errno = EINVAL;
184		_kvm_syserr(kd, kd->program, "empty file");
185		goto failed;
186	}
187	if (fcntl(kd->pmfd, F_SETFD, FD_CLOEXEC) < 0) {
188		_kvm_syserr(kd, kd->program, "%s", mf);
189		goto failed;
190	}
191	if (S_ISCHR(st.st_mode)) {
192		/*
193		 * If this is a character special device, then check that
194		 * it's /dev/mem.  If so, open kmem too.  (Maybe we should
195		 * make it work for either /dev/mem or /dev/kmem -- in either
196		 * case you're working with a live kernel.)
197		 */
198		if (strcmp(mf, _PATH_DEVNULL) == 0) {
199			kd->vmfd = open(_PATH_DEVNULL, O_RDONLY);
200			return (kd);
201		} else if (strcmp(mf, _PATH_MEM) == 0) {
202			if ((kd->vmfd = open(_PATH_KMEM, flag)) < 0) {
203				_kvm_syserr(kd, kd->program, "%s", _PATH_KMEM);
204				goto failed;
205			}
206			if (fcntl(kd->vmfd, F_SETFD, FD_CLOEXEC) < 0) {
207				_kvm_syserr(kd, kd->program, "%s", _PATH_KMEM);
208				goto failed;
209			}
210			return (kd);
211		}
212	}
213	/*
214	 * This is a crash dump.
215	 * Initialize the virtual address translation machinery,
216	 * but first setup the namelist fd.
217	 */
218	if ((kd->nlfd = open(uf, O_RDONLY, 0)) < 0) {
219		_kvm_syserr(kd, kd->program, "%s", uf);
220		goto failed;
221	}
222	if (fcntl(kd->nlfd, F_SETFD, FD_CLOEXEC) < 0) {
223		_kvm_syserr(kd, kd->program, "%s", uf);
224		goto failed;
225	}
226	if (_kvm_initvtop(kd) < 0)
227		goto failed;
228	return (kd);
229failed:
230	/*
231	 * Copy out the error if doing sane error semantics.
232	 */
233	if (errout != 0)
234		strlcpy(errout, kd->errbuf, _POSIX2_LINE_MAX);
235	(void)kvm_close(kd);
236	return (0);
237}
238
239kvm_t *
240kvm_openfiles(uf, mf, sf, flag, errout)
241	const char *uf;
242	const char *mf;
243	const char *sf __unused;
244	int flag;
245	char *errout;
246{
247	kvm_t *kd;
248
249	if ((kd = malloc(sizeof(*kd))) == NULL) {
250		(void)strlcpy(errout, strerror(errno), _POSIX2_LINE_MAX);
251		return (0);
252	}
253	memset(kd, 0, sizeof(*kd));
254	kd->program = 0;
255	return (_kvm_open(kd, uf, mf, flag, errout));
256}
257
258kvm_t *
259kvm_open(uf, mf, sf, flag, errstr)
260	const char *uf;
261	const char *mf;
262	const char *sf __unused;
263	int flag;
264	const char *errstr;
265{
266	kvm_t *kd;
267
268	if ((kd = malloc(sizeof(*kd))) == NULL) {
269		if (errstr != NULL)
270			(void)fprintf(stderr, "%s: %s\n",
271				      errstr, strerror(errno));
272		return (0);
273	}
274	memset(kd, 0, sizeof(*kd));
275	kd->program = errstr;
276	return (_kvm_open(kd, uf, mf, flag, NULL));
277}
278
279int
280kvm_close(kd)
281	kvm_t *kd;
282{
283	int error = 0;
284
285	if (kd->pmfd >= 0)
286		error |= close(kd->pmfd);
287	if (kd->vmfd >= 0)
288		error |= close(kd->vmfd);
289	if (kd->nlfd >= 0)
290		error |= close(kd->nlfd);
291	if (kd->vmst)
292		_kvm_freevtop(kd);
293	if (kd->procbase != 0)
294		free((void *)kd->procbase);
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
311	/*
312	 * If we can't use the kld symbol lookup, revert to the
313	 * slow library call.
314	 */
315	if (!ISALIVE(kd))
316		return (__fdnlist(kd->nlfd, nl));
317
318	/*
319	 * We can use the kld lookup syscall.  Go through each nlist entry
320	 * and look it up with a kldsym(2) syscall.
321	 */
322	nvalid = 0;
323	for (p = nl; p->n_name && p->n_name[0]; ++p) {
324		lookup.version = sizeof(lookup);
325		lookup.symname = p->n_name;
326		lookup.symvalue = 0;
327		lookup.symsize = 0;
328
329		if (lookup.symname[0] == '_')
330			lookup.symname++;
331
332		if (kldsym(0, KLDSYM_LOOKUP, &lookup) != -1) {
333			p->n_type = N_TEXT;
334			p->n_other = 0;
335			p->n_desc = 0;
336			p->n_value = lookup.symvalue;
337			++nvalid;
338			/* lookup.symsize */
339		}
340	}
341	/*
342	 * Return the number of entries that weren't found.
343	 */
344	return ((p - nl) - nvalid);
345}
346
347ssize_t
348kvm_read(kd, kva, buf, len)
349	kvm_t *kd;
350	u_long kva;
351	void *buf;
352	size_t len;
353{
354	int cc;
355	char *cp;
356
357	if (ISALIVE(kd)) {
358		/*
359		 * We're using /dev/kmem.  Just read straight from the
360		 * device and let the active kernel do the address translation.
361		 */
362		errno = 0;
363		if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
364			_kvm_err(kd, 0, "invalid address (%x)", kva);
365			return (-1);
366		}
367		cc = read(kd->vmfd, buf, len);
368		if (cc < 0) {
369			_kvm_syserr(kd, 0, "kvm_read");
370			return (-1);
371		} else if (cc < len)
372			_kvm_err(kd, kd->program, "short read");
373		return (cc);
374	} else {
375		cp = buf;
376		while (len > 0) {
377			off_t pa;
378
379			cc = _kvm_kvatop(kd, kva, &pa);
380			if (cc == 0)
381				return (-1);
382			if (cc > len)
383				cc = len;
384			errno = 0;
385			if (lseek(kd->pmfd, pa, 0) == -1 && errno != 0) {
386				_kvm_syserr(kd, 0, _PATH_MEM);
387				break;
388			}
389			cc = read(kd->pmfd, cp, cc);
390			if (cc < 0) {
391				_kvm_syserr(kd, kd->program, "kvm_read");
392				break;
393			}
394			/*
395			 * If kvm_kvatop returns a bogus value or our core
396			 * file is truncated, we might wind up seeking beyond
397			 * the end of the core file in which case the read will
398			 * return 0 (EOF).
399			 */
400			if (cc == 0)
401				break;
402			cp += cc;
403			kva += cc;
404			len -= cc;
405		}
406		return (cp - (char *)buf);
407	}
408	/* NOTREACHED */
409}
410
411ssize_t
412kvm_write(kd, kva, buf, len)
413	kvm_t *kd;
414	u_long kva;
415	const void *buf;
416	size_t len;
417{
418	int cc;
419
420	if (ISALIVE(kd)) {
421		/*
422		 * Just like kvm_read, only we write.
423		 */
424		errno = 0;
425		if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
426			_kvm_err(kd, 0, "invalid address (%x)", kva);
427			return (-1);
428		}
429		cc = write(kd->vmfd, buf, len);
430		if (cc < 0) {
431			_kvm_syserr(kd, 0, "kvm_write");
432			return (-1);
433		} else if (cc < len)
434			_kvm_err(kd, kd->program, "short write");
435		return (cc);
436	} else {
437		_kvm_err(kd, kd->program,
438		    "kvm_write not implemented for dead kernels");
439		return (-1);
440	}
441	/* NOTREACHED */
442}
443