1 /*-
2 * Copyright (c) 1998 John D. Polstra
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 * $FreeBSD: src/usr.bin/gcore/elfcore.c,v 1.5.2.3 2001/07/11 23:59:11 obrien Exp $
27 */
28
29 #define _KERNEL_STRUCTURES
30
31 #include <sys/param.h>
32 #include <sys/lock.h>
33 #include <sys/procfs.h>
34 #include <machine/elf.h>
35 #include <vm/vm_param.h>
36 #include <vm/vm.h>
37 #include <vm/pmap.h>
38 #include <vm/vm_map.h>
39 #include <err.h>
40 #include <errno.h>
41 #include <fcntl.h>
42 #include <stdio.h>
43 #include <stdlib.h>
44 #include <string.h>
45 #include <unistd.h>
46
47 #include "extern.h"
48
49 extern ssize_t gcore_seg_limit;
50 extern int gcore_verbose;
51
52 /*
53 * Code for generating ELF core dumps.
54 */
55
56 typedef void (*segment_callback)(vm_map_entry_t, void *);
57
58 /* Closure for cb_put_phdr(). */
59 struct phdr_closure {
60 Elf_Phdr *phdr; /* Program header to fill in */
61 Elf_Off offset; /* Offset of segment in core file */
62 };
63
64 /* Closure for cb_size_segment(). */
65 struct sseg_closure {
66 int count; /* Count of writable segments. */
67 size_t size; /* Total size of all writable segments. */
68 };
69
70 static void cb_put_phdr(vm_map_entry_t, void *);
71 static void cb_size_segment(vm_map_entry_t, void *);
72 static void each_writable_segment(vm_map_entry_t, segment_callback,
73 void *closure);
74 static void elf_corehdr(int fd, pid_t, vm_map_entry_t, int numsegs,
75 void *hdr, size_t hdrsize);
76 static void elf_puthdr(vm_map_entry_t, void *, size_t *,
77 const prstatus_t *, const prfpregset_t *, const prpsinfo_t *, int numsegs);
78 static void elf_putnote(void *dst, size_t *off, const char *name, int type,
79 const void *desc, size_t descsz);
80 static void freemap(vm_map_entry_t);
81 static void readhdrinfo(pid_t, prstatus_t *, prfpregset_t *, prpsinfo_t *);
82 static vm_map_entry_t readmap(pid_t);
83
84 /*
85 * Write an ELF coredump for the given pid to the given fd.
86 */
87 void
elf_coredump(int fd,pid_t pid)88 elf_coredump(int fd, pid_t pid)
89 {
90 vm_map_entry_t map;
91 struct sseg_closure seginfo;
92 void *hdr;
93 size_t hdrsize;
94 char memname[64];
95 int memfd;
96 Elf_Phdr *php;
97 int i;
98
99 /* Get the program's memory map. */
100 map = readmap(pid);
101
102 /* Size the program segments. */
103 seginfo.count = 0;
104 seginfo.size = 0;
105 each_writable_segment(map, cb_size_segment, &seginfo);
106
107 /*
108 * Calculate the size of the core file header area by making
109 * a dry run of generating it. Nothing is written, but the
110 * size is calculated.
111 */
112 hdrsize = 0;
113 elf_puthdr(map, NULL, &hdrsize, NULL, NULL, NULL, seginfo.count);
114
115 /*
116 * Allocate memory for building the header, fill it up,
117 * and write it out.
118 */
119 hdr = malloc(hdrsize);
120 if ((hdr = malloc(hdrsize)) == NULL)
121 errx(1, "out of memory");
122 elf_corehdr(fd, pid, map, seginfo.count, hdr, hdrsize);
123
124 /* Write the contents of all of the writable segments. */
125 snprintf(memname, sizeof memname, "/proc/%d/mem", pid);
126 if ((memfd = open(memname, O_RDONLY)) == -1)
127 err(1, "cannot open %s", memname);
128
129 php = (Elf_Phdr *)((char *)hdr + sizeof(Elf_Ehdr)) + 1;
130 for (i = 0; i < seginfo.count; i++) {
131 long nleft = php->p_filesz;
132
133 lseek(memfd, (off_t)php->p_vaddr, SEEK_SET);
134 while (nleft > 0) {
135 char buf[65536];
136 ssize_t nwant;
137 ssize_t ngot;
138
139 nwant = (ssize_t)nleft;
140 if (nwant > sizeof buf)
141 nwant = sizeof buf;
142 ngot = read(memfd, buf, nwant);
143 if (ngot == -1)
144 err(1, "read from %s", memname);
145 if (ngot < nwant)
146 errx(1, "short read from %s:"
147 " wanted %zd, got %zd\n", memname,
148 nwant, ngot);
149 ngot = write(fd, buf, nwant);
150 if (ngot == -1)
151 err(1, "write of segment %d failed", i);
152 if (ngot != nwant)
153 errx(1, "short write");
154 nleft -= nwant;
155 }
156 php++;
157 }
158 close(memfd);
159 free(hdr);
160 freemap(map);
161 }
162
163 /*
164 * A callback for each_writable_segment() to write out the segment's
165 * program header entry.
166 */
167 static void
cb_put_phdr(vm_map_entry_t entry,void * closure)168 cb_put_phdr(vm_map_entry_t entry, void *closure)
169 {
170 struct phdr_closure *phc = (struct phdr_closure *)closure;
171 Elf_Phdr *phdr = phc->phdr;
172
173 phc->offset = round_page(phc->offset);
174
175 phdr->p_type = PT_LOAD;
176 phdr->p_offset = phc->offset;
177 phdr->p_vaddr = entry->ba.start;
178 phdr->p_paddr = 0;
179 phdr->p_filesz = phdr->p_memsz = entry->ba.end - entry->ba.start;
180 phdr->p_align = PAGE_SIZE;
181 phdr->p_flags = 0;
182 if (entry->protection & VM_PROT_READ)
183 phdr->p_flags |= PF_R;
184 if (entry->protection & VM_PROT_WRITE)
185 phdr->p_flags |= PF_W;
186 if (entry->protection & VM_PROT_EXECUTE)
187 phdr->p_flags |= PF_X;
188
189 phc->offset += phdr->p_filesz;
190 phc->phdr++;
191 }
192
193 /*
194 * A callback for each_writable_segment() to gather information about
195 * the number of segments and their total size.
196 */
197 static void
cb_size_segment(vm_map_entry_t entry,void * closure)198 cb_size_segment(vm_map_entry_t entry, void *closure)
199 {
200 struct sseg_closure *ssc = (struct sseg_closure *)closure;
201
202 ssc->count++;
203 ssc->size += entry->ba.end - entry->ba.start;
204 }
205
206 /*
207 * For each segment in the given memory map, call the given function
208 * with a pointer to the map entry and some arbitrary caller-supplied
209 * data.
210 */
211 static void
each_writable_segment(vm_map_entry_t map,segment_callback func,void * closure)212 each_writable_segment(vm_map_entry_t map, segment_callback func, void *closure)
213 {
214 vm_map_entry_t entry;
215
216 for (entry = map; entry; entry = entry->rb_entry.rbe_parent)
217 (*func)(entry, closure);
218 }
219
220 /*
221 * Write the core file header to the file, including padding up to
222 * the page boundary.
223 */
224 static void
elf_corehdr(int fd,pid_t pid,vm_map_entry_t map,int numsegs,void * hdr,size_t hdrsize)225 elf_corehdr(int fd, pid_t pid, vm_map_entry_t map, int numsegs, void *hdr,
226 size_t hdrsize)
227 {
228 size_t off;
229 prstatus_t status;
230 prfpregset_t fpregset;
231 prpsinfo_t psinfo;
232
233 /* Gather the information for the header. */
234 readhdrinfo(pid, &status, &fpregset, &psinfo);
235
236 /* Fill in the header. */
237 memset(hdr, 0, hdrsize);
238 off = 0;
239 elf_puthdr(map, hdr, &off, &status, &fpregset, &psinfo, numsegs);
240
241 /* Write it to the core file. */
242 if (write(fd, hdr, hdrsize) == -1)
243 err(1, "write");
244 }
245
246 /*
247 * Generate the ELF coredump header into the buffer at "dst". "dst" may
248 * be NULL, in which case the header is sized but not actually generated.
249 */
250 static void
elf_puthdr(vm_map_entry_t map,void * dst,size_t * off,const prstatus_t * status,const prfpregset_t * fpregset,const prpsinfo_t * psinfo,int numsegs)251 elf_puthdr(vm_map_entry_t map, void *dst, size_t *off, const prstatus_t *status,
252 const prfpregset_t *fpregset, const prpsinfo_t *psinfo, int numsegs)
253 {
254 size_t ehoff;
255 size_t phoff;
256 size_t noteoff;
257 size_t notesz;
258
259 ehoff = *off;
260 *off += sizeof(Elf_Ehdr);
261
262 phoff = *off;
263 *off += (numsegs + 1) * sizeof(Elf_Phdr);
264
265 noteoff = *off;
266 elf_putnote(dst, off, "FreeBSD", NT_PRSTATUS, status,
267 sizeof *status);
268 elf_putnote(dst, off, "FreeBSD", NT_FPREGSET, fpregset,
269 sizeof *fpregset);
270 elf_putnote(dst, off, "FreeBSD", NT_PRPSINFO, psinfo,
271 sizeof *psinfo);
272 notesz = *off - noteoff;
273
274 /* Align up to a page boundary for the program segments. */
275 *off = round_page(*off);
276
277 if (dst != NULL) {
278 Elf_Ehdr *ehdr;
279 Elf_Phdr *phdr;
280 struct phdr_closure phc;
281
282 /*
283 * Fill in the ELF header.
284 */
285 ehdr = (Elf_Ehdr *)((char *)dst + ehoff);
286 ehdr->e_ident[EI_MAG0] = ELFMAG0;
287 ehdr->e_ident[EI_MAG1] = ELFMAG1;
288 ehdr->e_ident[EI_MAG2] = ELFMAG2;
289 ehdr->e_ident[EI_MAG3] = ELFMAG3;
290 ehdr->e_ident[EI_CLASS] = ELF_CLASS;
291 ehdr->e_ident[EI_DATA] = ELF_DATA;
292 ehdr->e_ident[EI_VERSION] = EV_CURRENT;
293 ehdr->e_ident[EI_OSABI] = ELFOSABI_NONE;
294 ehdr->e_ident[EI_ABIVERSION] = 0;
295 ehdr->e_ident[EI_PAD] = 0;
296 ehdr->e_type = ET_CORE;
297 ehdr->e_machine = ELF_ARCH;
298 ehdr->e_version = EV_CURRENT;
299 ehdr->e_entry = 0;
300 ehdr->e_phoff = phoff;
301 ehdr->e_flags = 0;
302 ehdr->e_ehsize = sizeof(Elf_Ehdr);
303 ehdr->e_phentsize = sizeof(Elf_Phdr);
304 ehdr->e_phnum = numsegs + 1;
305 ehdr->e_shentsize = sizeof(Elf_Shdr);
306 ehdr->e_shnum = 0;
307 ehdr->e_shstrndx = SHN_UNDEF;
308
309 /*
310 * Fill in the program header entries.
311 */
312 phdr = (Elf_Phdr *)((char *)dst + phoff);
313
314 /* The note segement. */
315 phdr->p_type = PT_NOTE;
316 phdr->p_offset = noteoff;
317 phdr->p_vaddr = 0;
318 phdr->p_paddr = 0;
319 phdr->p_filesz = notesz;
320 phdr->p_memsz = 0;
321 phdr->p_flags = 0;
322 phdr->p_align = 0;
323 phdr++;
324
325 /* All the writable segments from the program. */
326 phc.phdr = phdr;
327 phc.offset = *off;
328 each_writable_segment(map, cb_put_phdr, &phc);
329 }
330 }
331
332 /*
333 * Emit one note section to "dst", or just size it if "dst" is NULL.
334 */
335 static void
elf_putnote(void * dst,size_t * off,const char * name,int type,const void * desc,size_t descsz)336 elf_putnote(void *dst, size_t *off, const char *name, int type,
337 const void *desc, size_t descsz)
338 {
339 Elf_Note note;
340
341 note.n_namesz = strlen(name) + 1;
342 note.n_descsz = descsz;
343 note.n_type = type;
344 if (dst != NULL)
345 bcopy(¬e, (char *)dst + *off, sizeof note);
346 *off += sizeof note;
347 if (dst != NULL)
348 bcopy(name, (char *)dst + *off, note.n_namesz);
349 *off += roundup2(note.n_namesz, sizeof(Elf_Size));
350 if (dst != NULL)
351 bcopy(desc, (char *)dst + *off, note.n_descsz);
352 *off += roundup2(note.n_descsz, sizeof(Elf_Size));
353 }
354
355 /*
356 * Free the memory map.
357 */
358 static void
freemap(vm_map_entry_t map)359 freemap(vm_map_entry_t map)
360 {
361 while (map != NULL) {
362 vm_map_entry_t next = map->rb_entry.rbe_parent;
363 free(map);
364 map = next;
365 }
366 }
367
368 /*
369 * Read the process information necessary to fill in the core file's header.
370 */
371 static void
readhdrinfo(pid_t pid,prstatus_t * status,prfpregset_t * fpregset,prpsinfo_t * psinfo)372 readhdrinfo(pid_t pid, prstatus_t *status, prfpregset_t *fpregset,
373 prpsinfo_t *psinfo)
374 {
375 char name[64];
376 char line[256];
377 int fd;
378 int i;
379 int n;
380
381 memset(status, 0, sizeof *status);
382 status->pr_version = PRSTATUS_VERSION;
383 status->pr_statussz = sizeof(prstatus_t);
384 status->pr_gregsetsz = sizeof(gregset_t);
385 status->pr_fpregsetsz = sizeof(fpregset_t);
386 status->pr_osreldate = __DragonFly_version;
387 status->pr_pid = pid;
388
389 memset(fpregset, 0, sizeof *fpregset);
390
391 memset(psinfo, 0, sizeof *psinfo);
392 psinfo->pr_version = PRPSINFO_VERSION;
393 psinfo->pr_psinfosz = sizeof(prpsinfo_t);
394
395 /* Read the general registers. */
396 snprintf(name, sizeof name, "/proc/%d/regs", pid);
397 if ((fd = open(name, O_RDONLY)) == -1)
398 err(1, "cannot open %s", name);
399 if ((n = read(fd, &status->pr_reg, sizeof status->pr_reg)) == -1)
400 err(1, "read error from %s", name);
401 if (n < sizeof status->pr_reg)
402 errx(1, "short read from %s: wanted %zu, got %d",
403 name, sizeof(status->pr_reg), n);
404 close(fd);
405
406 /* Read the floating point registers. */
407 snprintf(name, sizeof name, "/proc/%d/fpregs", pid);
408 if ((fd = open(name, O_RDONLY)) == -1)
409 err(1, "cannot open %s", name);
410 if ((n = read(fd, fpregset, sizeof *fpregset)) == -1)
411 err(1, "read error from %s", name);
412 if (n < sizeof *fpregset)
413 errx(1, "short read from %s: wanted %zu, got %d",
414 name, sizeof(*fpregset), n);
415 close(fd);
416
417 /* Read and parse the process status. */
418 snprintf(name, sizeof name, "/proc/%d/status", pid);
419 if ((fd = open(name, O_RDONLY)) == -1)
420 err(1, "cannot open %s", name);
421 if ((n = read(fd, line, sizeof line - 1)) == -1)
422 err(1, "read error from %s", name);
423 if (n > MAXCOMLEN)
424 n = MAXCOMLEN;
425 for (i = 0; i < n && line[i] != ' '; i++)
426 psinfo->pr_fname[i] = line[i];
427 strncpy(psinfo->pr_psargs, psinfo->pr_fname, PRARGSZ);
428 close(fd);
429 }
430
431 /*
432 * Read the process's memory map using procfs, and return a list of
433 * VM map entries. Only the non-device read/writable segments are
434 * returned. The map entries in the list aren't fully filled in; only
435 * the items we need are present.
436 */
437 static vm_map_entry_t
readmap(pid_t pid)438 readmap(pid_t pid)
439 {
440 char mapname[64];
441 int mapfd;
442 ssize_t mapsize;
443 size_t bufsize;
444 char *mapbuf;
445 int pos;
446 vm_map_entry_t map;
447 vm_map_entry_t *linkp;
448
449 snprintf(mapname, sizeof mapname, "/proc/%d/map", pid);
450 if ((mapfd = open(mapname, O_RDONLY)) == -1)
451 err(1, "cannot open %s", mapname);
452
453 /*
454 * Procfs requires (for consistency) that the entire memory map
455 * be read with a single read() call. Start with a reasonbly sized
456 * buffer, and double it until it is big enough.
457 */
458 bufsize = 65536;
459 mapbuf = NULL;
460 for ( ; ; ) {
461 if ((mapbuf = realloc(mapbuf, bufsize + 1)) == NULL)
462 errx(1, "out of memory");
463 mapsize = read(mapfd, mapbuf, bufsize);
464 if ((mapsize != -1 || errno != EFBIG) && mapsize != bufsize) {
465 break;
466 }
467 bufsize *= 2;
468 /* This lseek shouldn't be necessary, but it is. */
469 lseek(mapfd, (off_t)0, SEEK_SET);
470 }
471 if (mapsize == -1)
472 err(1, "read error from %s", mapname);
473 if (mapsize == 0)
474 errx(1, "empty map file %s", mapname);
475 mapbuf[mapsize] = 0;
476 close(mapfd);
477
478 pos = 0;
479 map = NULL;
480 linkp = ↦
481 while (pos < mapsize) {
482 vm_map_entry_t ent;
483 vm_offset_t start;
484 vm_offset_t end;
485 char prot[4];
486 char type[16];
487 int n;
488 int len;
489 int skipme = 0;
490
491 len = 0;
492 n = sscanf(mapbuf + pos, "%lx %lx %*d %*d %*x %3[-rwx]"
493 " %*d %*d %*x %*s %*s %15s %*s%*[\n]%n",
494 &start, &end, prot, type, &len);
495 if (n != 4)
496 errx(1, "ill-formed line in %s: '%s'",
497 mapname, mapbuf);
498 pos += len;
499
500 /* Ignore segments of the wrong kind, and unwritable ones */
501 if (gcore_seg_limit >= 0 && end - start > gcore_seg_limit) {
502 skipme = 1;
503 }
504 if (strncmp(prot, "rw", 2) != 0 ||
505 (strcmp(type, "default") != 0 &&
506 strcmp(type, "vnode") != 0 &&
507 strcmp(type, "swap") != 0)) {
508 skipme = 2;
509 }
510 if (gcore_verbose || skipme == 1)
511 printf("%016lx-%016lx (%ldM) %s,%s",
512 start, end,
513 (end - start) / (1024 * 1024),
514 prot, type);
515 if (skipme) {
516 if (skipme == 1)
517 printf(" (ignored - seglimit)\n");
518 else if (gcore_verbose)
519 printf(" (ignored)\n");
520 continue;
521 }
522 if (gcore_verbose)
523 printf("\n");
524
525 if ((ent = (vm_map_entry_t)calloc(1, sizeof *ent)) == NULL)
526 errx(1, "out of memory");
527 ent->ba.start = start;
528 ent->ba.end = end;
529 ent->protection = VM_PROT_READ | VM_PROT_WRITE;
530 if (prot[2] == 'x')
531 ent->protection |= VM_PROT_EXECUTE;
532
533 *linkp = ent;
534 linkp = &ent->rb_entry.rbe_parent;
535 }
536 free(mapbuf);
537 return map;
538 }
539