1 /*- 2 * Copyright (c) 2007 Robert N. M. Watson 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 /*- 28 * Kernel text-dump support: write a series of text files to the dump 29 * partition for later recovery, including captured DDB output, kernel 30 * configuration, message buffer, and panic message. This allows for a more 31 * compact representation of critical debugging information than traditional 32 * binary dumps, as well as allowing dump information to be used without 33 * access to kernel symbols, source code, etc. 34 * 35 * Storage Layout 36 * -------------- 37 * 38 * Crash dumps are aligned to the end of the dump or swap partition in order 39 * to minimize the chances of swap duing fsck eating into the dump. However, 40 * unlike a memory dump, we don't know the size of the textdump a priori, so 41 * can't just write it out sequentially in order from a known starting point 42 * calculated with respect to the end of the partition. In order to address 43 * this, we actually write out the textdump in reverse block order, allowing 44 * us to directly align it to the end of the partition and then write out the 45 * dump header and trailer before and after it once done. savecore(8) must 46 * know to reverse the order of the blocks in order to produce a readable 47 * file. 48 * 49 * Data is written out in the ustar file format so that we can write data 50 * incrementally as a stream without reference to previous files. 51 * 52 * TODO 53 * ---- 54 * 55 * - Allow subsytems to register to submit files for inclusion in the text 56 * dump in a generic way. 57 */ 58 59 #include <sys/cdefs.h> 60 __FBSDID("$FreeBSD$"); 61 62 #include "opt_config.h" 63 64 #include <sys/param.h> 65 #include <sys/conf.h> 66 #include <sys/kernel.h> 67 #include <sys/kerneldump.h> 68 #include <sys/msgbuf.h> 69 #include <sys/sysctl.h> 70 #include <sys/systm.h> 71 #include <sys/vimage.h> 72 73 #include <ddb/ddb.h> 74 #include <ddb/db_lex.h> 75 76 static SYSCTL_NODE(_debug_ddb, OID_AUTO, textdump, CTLFLAG_RW, 0, 77 "DDB textdump options"); 78 79 /* 80 * Don't touch the first SIZEOF_METADATA bytes on the dump device. This is 81 * to protect us from metadata and metadata from us. 82 */ 83 #define SIZEOF_METADATA (64*1024) 84 85 /* 86 * Data is written out as a series of files in the ustar tar format. ustar 87 * is a simple streamed format consiting of a series of files prefixed with 88 * headers, and all padded to 512-byte block boundaries, which maps 89 * conveniently to our requirements. 90 */ 91 struct ustar_header { 92 char uh_filename[100]; 93 char uh_mode[8]; 94 char uh_tar_owner[8]; 95 char uh_tar_group[8]; 96 char uh_size[12]; 97 char uh_mtime[12]; 98 char uh_sum[8]; 99 char uh_type; 100 char uh_linkfile[100]; 101 char uh_ustar[6]; 102 char uh_version[2]; 103 char uh_owner[32]; 104 char uh_group[32]; 105 char uh_major[8]; 106 char uh_minor[8]; 107 char uh_filenameprefix[155]; 108 char uh_zeropad[12]; 109 } __packed; 110 111 /* 112 * Various size assertions -- pretty much everything must be one block in 113 * size. 114 */ 115 CTASSERT(sizeof(struct kerneldumpheader) == TEXTDUMP_BLOCKSIZE); 116 CTASSERT(sizeof(struct ustar_header) == TEXTDUMP_BLOCKSIZE); 117 118 /* 119 * Is a textdump scheduled? If so, the shutdown code will invoke our dumpsys 120 * routine instead of the machine-dependent kernel dump routine. 121 */ 122 int textdump_pending; 123 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, pending, CTLFLAG_RW, 124 &textdump_pending, 0, 125 "Perform textdump instead of regular kernel dump."); 126 127 /* 128 * Various constants for tar headers and contents. 129 */ 130 #define TAR_USER "root" 131 #define TAR_GROUP "wheel" 132 #define TAR_UID "0" 133 #define TAR_GID "0" 134 #define TAR_MODE "0600" 135 #define TAR_USTAR "ustar" 136 137 #define TAR_CONFIG_FILENAME "config.txt" /* Kernel configuration. */ 138 #define TAR_MSGBUF_FILENAME "msgbuf.txt" /* Kernel messsage buffer. */ 139 #define TAR_PANIC_FILENAME "panic.txt" /* Panic message. */ 140 #define TAR_VERSION_FILENAME "version.txt" /* Kernel version. */ 141 142 /* 143 * Configure which files will be dumped. 144 */ 145 #ifdef INCLUDE_CONFIG_FILE 146 static int textdump_do_config = 1; 147 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_config, CTLFLAG_RW, 148 &textdump_do_config, 0, "Dump kernel configuration in textdump"); 149 #endif 150 151 static int textdump_do_ddb = 1; 152 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_ddb, CTLFLAG_RW, 153 &textdump_do_ddb, 0, "Dump DDB captured output in textdump"); 154 155 static int textdump_do_msgbuf = 1; 156 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_msgbuf, CTLFLAG_RW, 157 &textdump_do_msgbuf, 0, "Dump kernel message buffer in textdump"); 158 159 static int textdump_do_panic = 1; 160 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_panic, CTLFLAG_RW, 161 &textdump_do_panic, 0, "Dump kernel panic message in textdump"); 162 163 static int textdump_do_version = 1; 164 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_version, CTLFLAG_RW, 165 &textdump_do_version, 0, "Dump kernel version string in textdump"); 166 167 /* 168 * State related to incremental writing of blocks to disk. 169 */ 170 static off_t textdump_offset; /* Offset of next sequential write. */ 171 static int textdump_error; /* Carried write error, if any. */ 172 173 /* 174 * Statically allocate space to prepare block-sized headers and data. 175 */ 176 char textdump_block_buffer[TEXTDUMP_BLOCKSIZE]; 177 static struct kerneldumpheader kdh; 178 179 /* 180 * Text dumps are prefixed with a normal kernel dump header but with a 181 * different magic number to allow them to be uniquely identified. 182 */ 183 static void 184 mkdumpheader(struct kerneldumpheader *kdh, uint32_t archver, 185 uint64_t dumplen, uint32_t blksz) 186 { 187 188 bzero(kdh, sizeof(*kdh)); 189 strncpy(kdh->magic, TEXTDUMPMAGIC, sizeof(kdh->magic)); 190 strncpy(kdh->architecture, MACHINE_ARCH, sizeof(kdh->architecture)); 191 kdh->version = htod32(KERNELDUMPVERSION); 192 kdh->architectureversion = htod32(archver); 193 kdh->dumplength = htod64(dumplen); 194 kdh->dumptime = htod64(time_second); 195 kdh->blocksize = htod32(blksz); 196 strncpy(kdh->hostname, G_hostname, sizeof(kdh->hostname)); 197 strncpy(kdh->versionstring, version, sizeof(kdh->versionstring)); 198 if (panicstr != NULL) 199 strncpy(kdh->panicstring, panicstr, sizeof(kdh->panicstring)); 200 kdh->parity = kerneldump_parity(kdh); 201 } 202 203 /* 204 * Calculate and fill in the checksum for a ustar header. 205 */ 206 static void 207 ustar_checksum(struct ustar_header *uhp) 208 { 209 u_int sum; 210 int i; 211 212 for (i = 0; i < sizeof(uhp->uh_sum); i++) 213 uhp->uh_sum[i] = ' '; 214 sum = 0; 215 for (i = 0; i < sizeof(*uhp); i++) 216 sum += ((u_char *)uhp)[i]; 217 snprintf(uhp->uh_sum, sizeof(uhp->uh_sum), "%6o", sum); 218 } 219 220 /* 221 * Each file in the tarball has a block-sized header with its name and other, 222 * largely hard-coded, properties. 223 */ 224 void 225 textdump_mkustar(char *block_buffer, const char *filename, u_int size) 226 { 227 struct ustar_header *uhp; 228 229 uhp = (struct ustar_header *)block_buffer; 230 bzero(uhp, sizeof(*uhp)); 231 strlcpy(uhp->uh_filename, filename, sizeof(uhp->uh_filename)); 232 strlcpy(uhp->uh_mode, TAR_MODE, sizeof(uhp->uh_mode)); 233 snprintf(uhp->uh_size, sizeof(uhp->uh_size), "%o", size); 234 strlcpy(uhp->uh_tar_owner, TAR_UID, sizeof(uhp->uh_tar_owner)); 235 strlcpy(uhp->uh_tar_group, TAR_GID, sizeof(uhp->uh_tar_group)); 236 strlcpy(uhp->uh_owner, TAR_USER, sizeof(uhp->uh_owner)); 237 strlcpy(uhp->uh_group, TAR_GROUP, sizeof(uhp->uh_group)); 238 snprintf(uhp->uh_mtime, sizeof(uhp->uh_mtime), "%lo", 239 (unsigned long)time_second); 240 uhp->uh_type = 0; 241 strlcpy(uhp->uh_ustar, TAR_USTAR, sizeof(uhp->uh_ustar)); 242 ustar_checksum(uhp); 243 } 244 245 /* 246 * textdump_writeblock() writes TEXTDUMP_BLOCKSIZE-sized blocks of data to 247 * the space between di->mediaoffset and di->mediaoffset + di->mediasize. It 248 * accepts an offset relative to di->mediaoffset. If we're carrying any 249 * error from previous I/O, return that error and don't continue to try to 250 * write. Most writers ignore the error and forge ahead on the basis that 251 * there's not much you can do. 252 */ 253 static int 254 textdump_writeblock(struct dumperinfo *di, off_t offset, char *buffer) 255 { 256 257 if (textdump_error) 258 return (textdump_error); 259 if (offset + TEXTDUMP_BLOCKSIZE > di->mediasize) 260 return (EIO); 261 if (offset < SIZEOF_METADATA) 262 return (ENOSPC); 263 textdump_error = dump_write(di, buffer, 0, offset + di->mediaoffset, 264 TEXTDUMP_BLOCKSIZE); 265 return (textdump_error); 266 } 267 268 /* 269 * Interfaces to save and restore the dump offset, so that printers can go 270 * back to rewrite a header if required, while avoiding their knowing about 271 * the global layout of the blocks. 272 * 273 * If we ever want to support writing textdumps to tape or other 274 * stream-oriented target, we'll need to remove this. 275 */ 276 void 277 textdump_saveoff(off_t *offsetp) 278 { 279 280 *offsetp = textdump_offset; 281 } 282 283 void 284 textdump_restoreoff(off_t offset) 285 { 286 287 textdump_offset = offset; 288 } 289 290 /* 291 * Interface to write the "next block" relative to the current offset; since 292 * we write backwards from the end of the partition, we subtract, but there's 293 * no reason for the caller to know this. 294 */ 295 int 296 textdump_writenextblock(struct dumperinfo *di, char *buffer) 297 { 298 int error; 299 300 error = textdump_writeblock(di, textdump_offset, buffer); 301 textdump_offset -= TEXTDUMP_BLOCKSIZE; 302 return (error); 303 } 304 305 #ifdef INCLUDE_CONFIG_FILE 306 extern char kernconfstring[]; 307 308 /* 309 * Dump kernel configuration. 310 */ 311 static void 312 textdump_dump_config(struct dumperinfo *di) 313 { 314 u_int count, fullblocks, len; 315 316 len = strlen(kernconfstring); 317 textdump_mkustar(textdump_block_buffer, TAR_CONFIG_FILENAME, len); 318 (void)textdump_writenextblock(di, textdump_block_buffer); 319 320 /* 321 * Write out all full blocks directly from the string, and handle any 322 * left-over bits by copying it to out to the local buffer and 323 * zero-padding it. 324 */ 325 fullblocks = len / TEXTDUMP_BLOCKSIZE; 326 for (count = 0; count < fullblocks; count++) 327 (void)textdump_writenextblock(di, kernconfstring + count * 328 TEXTDUMP_BLOCKSIZE); 329 if (len % TEXTDUMP_BLOCKSIZE != 0) { 330 bzero(textdump_block_buffer, TEXTDUMP_BLOCKSIZE); 331 bcopy(kernconfstring + count * TEXTDUMP_BLOCKSIZE, 332 textdump_block_buffer, len % TEXTDUMP_BLOCKSIZE); 333 (void)textdump_writenextblock(di, textdump_block_buffer); 334 } 335 } 336 #endif /* INCLUDE_CONFIG_FILE */ 337 338 /* 339 * Dump kernel message buffer. 340 */ 341 static void 342 textdump_dump_msgbuf(struct dumperinfo *di) 343 { 344 off_t end_offset, tarhdr_offset; 345 u_int i, len, offset, seq, total_len; 346 char buf[16]; 347 348 /* 349 * Write out a dummy tar header to advance the offset; we'll rewrite 350 * it later once we know the true size. 351 */ 352 textdump_saveoff(&tarhdr_offset); 353 textdump_mkustar(textdump_block_buffer, TAR_MSGBUF_FILENAME, 0); 354 (void)textdump_writenextblock(di, textdump_block_buffer); 355 356 /* 357 * Copy out the data in small chunks, but don't copy nuls that may be 358 * present if the message buffer has not yet completely filled at 359 * least once. 360 */ 361 total_len = 0; 362 offset = 0; 363 msgbuf_peekbytes(msgbufp, NULL, 0, &seq); 364 while ((len = msgbuf_peekbytes(msgbufp, buf, sizeof(buf), &seq)) > 0) { 365 for (i = 0; i < len; i++) { 366 if (buf[i] == '\0') 367 continue; 368 textdump_block_buffer[offset] = buf[i]; 369 offset++; 370 if (offset != sizeof(textdump_block_buffer)) 371 continue; 372 (void)textdump_writenextblock(di, 373 textdump_block_buffer); 374 total_len += offset; 375 offset = 0; 376 } 377 } 378 total_len += offset; /* Without the zero-padding. */ 379 if (offset != 0) { 380 bzero(textdump_block_buffer + offset, 381 sizeof(textdump_block_buffer) - offset); 382 (void)textdump_writenextblock(di, textdump_block_buffer); 383 } 384 385 /* 386 * Rewrite tar header to reflect how much was actually written. 387 */ 388 textdump_saveoff(&end_offset); 389 textdump_restoreoff(tarhdr_offset); 390 textdump_mkustar(textdump_block_buffer, TAR_MSGBUF_FILENAME, 391 total_len); 392 (void)textdump_writenextblock(di, textdump_block_buffer); 393 textdump_restoreoff(end_offset); 394 } 395 396 static void 397 textdump_dump_panic(struct dumperinfo *di) 398 { 399 u_int len; 400 401 /* 402 * Write out tar header -- we store up to one block of panic message. 403 */ 404 len = min(strlen(panicstr), TEXTDUMP_BLOCKSIZE); 405 textdump_mkustar(textdump_block_buffer, TAR_PANIC_FILENAME, len); 406 (void)textdump_writenextblock(di, textdump_block_buffer); 407 408 /* 409 * Zero-pad the panic string and write out block. 410 */ 411 bzero(textdump_block_buffer, sizeof(textdump_block_buffer)); 412 bcopy(panicstr, textdump_block_buffer, len); 413 (void)textdump_writenextblock(di, textdump_block_buffer); 414 } 415 416 static void 417 textdump_dump_version(struct dumperinfo *di) 418 { 419 u_int len; 420 421 /* 422 * Write out tar header -- at most one block of version information. 423 */ 424 len = min(strlen(version), TEXTDUMP_BLOCKSIZE); 425 textdump_mkustar(textdump_block_buffer, TAR_VERSION_FILENAME, len); 426 (void)textdump_writenextblock(di, textdump_block_buffer); 427 428 /* 429 * Zero pad the version string and write out block. 430 */ 431 bzero(textdump_block_buffer, sizeof(textdump_block_buffer)); 432 bcopy(version, textdump_block_buffer, len); 433 (void)textdump_writenextblock(di, textdump_block_buffer); 434 } 435 436 /* 437 * Commit text dump to disk. 438 */ 439 void 440 textdump_dumpsys(struct dumperinfo *di) 441 { 442 off_t dumplen, trailer_offset; 443 444 if (di->blocksize != TEXTDUMP_BLOCKSIZE) { 445 printf("Dump partition block size (%ju) not textdump " 446 "block size (%ju)", (uintmax_t)di->blocksize, 447 (uintmax_t)TEXTDUMP_BLOCKSIZE); 448 return; 449 } 450 451 /* 452 * We don't know a priori how large the dump will be, but we do know 453 * that we need to reserve space for metadata and that we need two 454 * dump headers. Also leave room for one ustar header and one block 455 * of data. 456 */ 457 if (di->mediasize < SIZEOF_METADATA + 2 * sizeof(kdh)) { 458 printf("Insufficient space on dump partition.\n"); 459 return; 460 } 461 textdump_error = 0; 462 463 /* 464 * Position the start of the dump so that we'll write the kernel dump 465 * trailer immediately before the end of the partition, and then work 466 * our way back. We will rewrite this header later to reflect the 467 * true size if things go well. 468 */ 469 textdump_offset = di->mediasize - sizeof(kdh); 470 textdump_saveoff(&trailer_offset); 471 mkdumpheader(&kdh, KERNELDUMP_TEXT_VERSION, 0, TEXTDUMP_BLOCKSIZE); 472 (void)textdump_writenextblock(di, (char *)&kdh); 473 474 /* 475 * Write a series of files in ustar format. 476 */ 477 if (textdump_do_ddb) 478 db_capture_dump(di); 479 #ifdef INCLUDE_CONFIG_FILE 480 if (textdump_do_config) 481 textdump_dump_config(di); 482 #endif 483 if (textdump_do_msgbuf) 484 textdump_dump_msgbuf(di); 485 if (textdump_do_panic && panicstr != NULL) 486 textdump_dump_panic(di); 487 if (textdump_do_version) 488 textdump_dump_version(di); 489 490 /* 491 * Now that we know the true size, we can write out the header, then 492 * seek back to the end and rewrite the trailer with the correct 493 * size. 494 */ 495 dumplen = trailer_offset - (textdump_offset + TEXTDUMP_BLOCKSIZE); 496 mkdumpheader(&kdh, KERNELDUMP_TEXT_VERSION, dumplen, 497 TEXTDUMP_BLOCKSIZE); 498 (void)textdump_writenextblock(di, (char *)&kdh); 499 textdump_restoreoff(trailer_offset); 500 (void)textdump_writenextblock(di, (char *)&kdh); 501 502 /* 503 * Terminate the dump, report any errors, and clear the pending flag. 504 */ 505 if (textdump_error == 0) 506 (void)dump_write(di, NULL, 0, 0, 0); 507 if (textdump_error == ENOSPC) 508 printf("Insufficient space on dump partition\n"); 509 else if (textdump_error != 0) 510 printf("Error %d writing dump\n", textdump_error); 511 else 512 printf("Textdump complete.\n"); 513 textdump_pending = 0; 514 } 515 516 /*- 517 * DDB(4) command to manage textdumps: 518 * 519 * textdump set - request a textdump 520 * textdump status - print DDB output textdump status 521 * textdump unset - clear textdump request 522 */ 523 static void 524 db_textdump_usage(void) 525 { 526 527 db_printf("textdump [unset|set|status]\n"); 528 } 529 530 void 531 db_textdump_cmd(db_expr_t addr, boolean_t have_addr, db_expr_t count, 532 char *modif) 533 { 534 int t; 535 536 t = db_read_token(); 537 if (t != tIDENT) { 538 db_textdump_usage(); 539 return; 540 } 541 if (db_read_token() != tEOL) { 542 db_textdump_usage(); 543 return; 544 } 545 if (strcmp(db_tok_string, "set") == 0) { 546 textdump_pending = 1; 547 db_printf("textdump set\n"); 548 } else if (strcmp(db_tok_string, "status") == 0) { 549 if (textdump_pending) 550 db_printf("textdump is set\n"); 551 else 552 db_printf("textdump is not set\n"); 553 } else if (strcmp(db_tok_string, "unset") == 0) { 554 textdump_pending = 0; 555 db_printf("textdump unset\n"); 556 } else 557 db_textdump_usage(); 558 } 559