xref: /freebsd/lib/libkvm/kvm.c (revision e1fe3dba5ce2826061f6489765be9b4a341736a9)
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("$FreeBSD$");
40 
41 #if defined(LIBC_SCCS) && !defined(lint)
42 #if 0
43 static 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 */
74 int __fdnlist(int, struct nlist *);
75 
76 char *
77 kvm_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  */
91 void
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 
108 void
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 
130 void *
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 
143 static 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);
229 failed:
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 
239 kvm_t *
240 kvm_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 
258 kvm_t *
259 kvm_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 
279 int
280 kvm_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 
302 int
303 kvm_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 
347 ssize_t
348 kvm_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 
411 ssize_t
412 kvm_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