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