1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2007 Robert N. M. Watson 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 /*- 30 * Kernel text-dump support: write a series of text files to the dump 31 * partition for later recovery, including captured DDB output, kernel 32 * configuration, message buffer, and panic message. This allows for a more 33 * compact representation of critical debugging information than traditional 34 * binary dumps, as well as allowing dump information to be used without 35 * access to kernel symbols, source code, etc. 36 * 37 * Storage Layout 38 * -------------- 39 * 40 * Crash dumps are aligned to the end of the dump or swap partition in order 41 * to minimize the chances of swap duing fsck eating into the dump. However, 42 * unlike a memory dump, we don't know the size of the textdump a priori, so 43 * can't just write it out sequentially in order from a known starting point 44 * calculated with respect to the end of the partition. In order to address 45 * this, we actually write out the textdump in reverse block order, allowing 46 * us to directly align it to the end of the partition and then write out the 47 * dump header and trailer before and after it once done. savecore(8) must 48 * know to reverse the order of the blocks in order to produce a readable 49 * file. 50 * 51 * Data is written out in the ustar file format so that we can write data 52 * incrementally as a stream without reference to previous files. 53 * 54 * TODO 55 * ---- 56 * 57 * - Allow subsystems to register to submit files for inclusion in the text 58 * dump in a generic way. 59 */ 60 61 #include <sys/cdefs.h> 62 __FBSDID("$FreeBSD$"); 63 64 #include "opt_config.h" 65 66 #include "opt_ddb.h" 67 68 #include <sys/param.h> 69 #include <sys/conf.h> 70 #include <sys/kernel.h> 71 #include <sys/kerneldump.h> 72 #include <sys/msgbuf.h> 73 #include <sys/sysctl.h> 74 #include <sys/systm.h> 75 76 #include <ddb/ddb.h> 77 #include <ddb/db_lex.h> 78 79 static SYSCTL_NODE(_debug_ddb, OID_AUTO, textdump, 80 CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 81 "DDB textdump options"); 82 83 /* 84 * Don't touch the first SIZEOF_METADATA bytes on the dump device. This is 85 * to protect us from metadata and metadata from us. 86 */ 87 #define SIZEOF_METADATA (64*1024) 88 89 /* 90 * Data is written out as a series of files in the ustar tar format. ustar 91 * is a simple streamed format consiting of a series of files prefixed with 92 * headers, and all padded to 512-byte block boundaries, which maps 93 * conveniently to our requirements. 94 */ 95 struct ustar_header { 96 char uh_filename[100]; 97 char uh_mode[8]; 98 char uh_tar_owner[8]; 99 char uh_tar_group[8]; 100 char uh_size[12]; 101 char uh_mtime[12]; 102 char uh_sum[8]; 103 char uh_type; 104 char uh_linkfile[100]; 105 char uh_ustar[6]; 106 char uh_version[2]; 107 char uh_owner[32]; 108 char uh_group[32]; 109 char uh_major[8]; 110 char uh_minor[8]; 111 char uh_filenameprefix[155]; 112 char uh_zeropad[12]; 113 } __packed; 114 115 /* 116 * Various size assertions -- pretty much everything must be one block in 117 * size. 118 */ 119 CTASSERT(sizeof(struct kerneldumpheader) == TEXTDUMP_BLOCKSIZE); 120 CTASSERT(sizeof(struct ustar_header) == TEXTDUMP_BLOCKSIZE); 121 122 /* 123 * Is a textdump scheduled? If so, the shutdown code will invoke our dumpsys 124 * routine instead of the machine-dependent kernel dump routine. 125 */ 126 #ifdef TEXTDUMP_PREFERRED 127 int textdump_pending = 1; 128 #else 129 int textdump_pending = 0; 130 #endif 131 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, pending, CTLFLAG_RW, 132 &textdump_pending, 0, 133 "Perform textdump instead of regular kernel dump."); 134 135 /* 136 * Various constants for tar headers and contents. 137 */ 138 #define TAR_USER "root" 139 #define TAR_GROUP "wheel" 140 #define TAR_UID "0" 141 #define TAR_GID "0" 142 #define TAR_MODE "0600" 143 #define TAR_USTAR "ustar" 144 145 #define TAR_CONFIG_FILENAME "config.txt" /* Kernel configuration. */ 146 #define TAR_MSGBUF_FILENAME "msgbuf.txt" /* Kernel messsage buffer. */ 147 #define TAR_PANIC_FILENAME "panic.txt" /* Panic message. */ 148 #define TAR_VERSION_FILENAME "version.txt" /* Kernel version. */ 149 150 /* 151 * Configure which files will be dumped. 152 */ 153 #ifdef INCLUDE_CONFIG_FILE 154 static int textdump_do_config = 1; 155 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_config, CTLFLAG_RW, 156 &textdump_do_config, 0, "Dump kernel configuration in textdump"); 157 #endif 158 159 static int textdump_do_ddb = 1; 160 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_ddb, CTLFLAG_RW, 161 &textdump_do_ddb, 0, "Dump DDB captured output in textdump"); 162 163 static int textdump_do_msgbuf = 1; 164 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_msgbuf, CTLFLAG_RW, 165 &textdump_do_msgbuf, 0, "Dump kernel message buffer in textdump"); 166 167 static int textdump_do_panic = 1; 168 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_panic, CTLFLAG_RW, 169 &textdump_do_panic, 0, "Dump kernel panic message in textdump"); 170 171 static int textdump_do_version = 1; 172 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_version, CTLFLAG_RW, 173 &textdump_do_version, 0, "Dump kernel version string in textdump"); 174 175 /* 176 * State related to incremental writing of blocks to disk. 177 */ 178 static off_t textdump_offset; /* Offset of next sequential write. */ 179 static int textdump_error; /* Carried write error, if any. */ 180 181 /* 182 * Statically allocate space to prepare block-sized headers and data. 183 */ 184 char textdump_block_buffer[TEXTDUMP_BLOCKSIZE]; 185 static struct kerneldumpheader kdh; 186 187 /* 188 * Calculate and fill in the checksum for a ustar header. 189 */ 190 static void 191 ustar_checksum(struct ustar_header *uhp) 192 { 193 u_int sum; 194 int i; 195 196 for (i = 0; i < sizeof(uhp->uh_sum); i++) 197 uhp->uh_sum[i] = ' '; 198 sum = 0; 199 for (i = 0; i < sizeof(*uhp); i++) 200 sum += ((u_char *)uhp)[i]; 201 snprintf(uhp->uh_sum, sizeof(uhp->uh_sum), "%6o", sum); 202 } 203 204 /* 205 * Each file in the tarball has a block-sized header with its name and other, 206 * largely hard-coded, properties. 207 */ 208 void 209 textdump_mkustar(char *block_buffer, const char *filename, u_int size) 210 { 211 struct ustar_header *uhp; 212 213 #ifdef TEXTDUMP_VERBOSE 214 if (textdump_error == 0) 215 printf("textdump: creating '%s'.\n", filename); 216 #endif 217 uhp = (struct ustar_header *)block_buffer; 218 bzero(uhp, sizeof(*uhp)); 219 strlcpy(uhp->uh_filename, filename, sizeof(uhp->uh_filename)); 220 strlcpy(uhp->uh_mode, TAR_MODE, sizeof(uhp->uh_mode)); 221 snprintf(uhp->uh_size, sizeof(uhp->uh_size), "%o", size); 222 strlcpy(uhp->uh_tar_owner, TAR_UID, sizeof(uhp->uh_tar_owner)); 223 strlcpy(uhp->uh_tar_group, TAR_GID, sizeof(uhp->uh_tar_group)); 224 strlcpy(uhp->uh_owner, TAR_USER, sizeof(uhp->uh_owner)); 225 strlcpy(uhp->uh_group, TAR_GROUP, sizeof(uhp->uh_group)); 226 snprintf(uhp->uh_mtime, sizeof(uhp->uh_mtime), "%lo", 227 (unsigned long)time_second); 228 uhp->uh_type = 0; 229 strlcpy(uhp->uh_ustar, TAR_USTAR, sizeof(uhp->uh_ustar)); 230 ustar_checksum(uhp); 231 } 232 233 /* 234 * textdump_writeblock() writes TEXTDUMP_BLOCKSIZE-sized blocks of data to 235 * the space between di->mediaoffset and di->mediaoffset + di->mediasize. It 236 * accepts an offset relative to di->mediaoffset. If we're carrying any 237 * error from previous I/O, return that error and don't continue to try to 238 * write. Most writers ignore the error and forge ahead on the basis that 239 * there's not much you can do. 240 */ 241 static int 242 textdump_writeblock(struct dumperinfo *di, off_t offset, char *buffer) 243 { 244 245 if (textdump_error) 246 return (textdump_error); 247 if (offset + TEXTDUMP_BLOCKSIZE > di->mediasize) 248 return (EIO); 249 if (offset < SIZEOF_METADATA) 250 return (ENOSPC); 251 textdump_error = dump_write(di, buffer, offset + di->mediaoffset, 252 TEXTDUMP_BLOCKSIZE); 253 if (textdump_error) 254 printf("textdump_writeblock: offset %jd, error %d\n", (intmax_t)offset, 255 textdump_error); 256 return (textdump_error); 257 } 258 259 /* 260 * Interfaces to save and restore the dump offset, so that printers can go 261 * back to rewrite a header if required, while avoiding their knowing about 262 * the global layout of the blocks. 263 * 264 * If we ever want to support writing textdumps to tape or other 265 * stream-oriented target, we'll need to remove this. 266 */ 267 void 268 textdump_saveoff(off_t *offsetp) 269 { 270 271 *offsetp = textdump_offset; 272 } 273 274 void 275 textdump_restoreoff(off_t offset) 276 { 277 278 textdump_offset = offset; 279 } 280 281 /* 282 * Interface to write the "next block" relative to the current offset; since 283 * we write backwards from the end of the partition, we subtract, but there's 284 * no reason for the caller to know this. 285 */ 286 int 287 textdump_writenextblock(struct dumperinfo *di, char *buffer) 288 { 289 int error; 290 291 error = textdump_writeblock(di, textdump_offset, buffer); 292 textdump_offset -= TEXTDUMP_BLOCKSIZE; 293 return (error); 294 } 295 296 #ifdef INCLUDE_CONFIG_FILE 297 extern char kernconfstring[]; 298 299 /* 300 * Dump kernel configuration. 301 */ 302 static void 303 textdump_dump_config(struct dumperinfo *di) 304 { 305 u_int count, fullblocks, len; 306 307 len = strlen(kernconfstring); 308 textdump_mkustar(textdump_block_buffer, TAR_CONFIG_FILENAME, len); 309 (void)textdump_writenextblock(di, textdump_block_buffer); 310 311 /* 312 * Write out all full blocks directly from the string, and handle any 313 * left-over bits by copying it to out to the local buffer and 314 * zero-padding it. 315 */ 316 fullblocks = len / TEXTDUMP_BLOCKSIZE; 317 for (count = 0; count < fullblocks; count++) 318 (void)textdump_writenextblock(di, kernconfstring + count * 319 TEXTDUMP_BLOCKSIZE); 320 if (len % TEXTDUMP_BLOCKSIZE != 0) { 321 bzero(textdump_block_buffer, TEXTDUMP_BLOCKSIZE); 322 bcopy(kernconfstring + count * TEXTDUMP_BLOCKSIZE, 323 textdump_block_buffer, len % TEXTDUMP_BLOCKSIZE); 324 (void)textdump_writenextblock(di, textdump_block_buffer); 325 } 326 } 327 #endif /* INCLUDE_CONFIG_FILE */ 328 329 /* 330 * Dump kernel message buffer. 331 */ 332 static void 333 textdump_dump_msgbuf(struct dumperinfo *di) 334 { 335 off_t end_offset, tarhdr_offset; 336 u_int i, len, offset, seq, total_len; 337 char buf[16]; 338 339 /* 340 * Write out a dummy tar header to advance the offset; we'll rewrite 341 * it later once we know the true size. 342 */ 343 textdump_saveoff(&tarhdr_offset); 344 textdump_mkustar(textdump_block_buffer, TAR_MSGBUF_FILENAME, 0); 345 (void)textdump_writenextblock(di, textdump_block_buffer); 346 347 /* 348 * Copy out the data in small chunks, but don't copy nuls that may be 349 * present if the message buffer has not yet completely filled at 350 * least once. 351 */ 352 total_len = 0; 353 offset = 0; 354 msgbuf_peekbytes(msgbufp, NULL, 0, &seq); 355 while ((len = msgbuf_peekbytes(msgbufp, buf, sizeof(buf), &seq)) > 0) { 356 for (i = 0; i < len; i++) { 357 if (buf[i] == '\0') 358 continue; 359 textdump_block_buffer[offset] = buf[i]; 360 offset++; 361 if (offset != sizeof(textdump_block_buffer)) 362 continue; 363 (void)textdump_writenextblock(di, 364 textdump_block_buffer); 365 total_len += offset; 366 offset = 0; 367 } 368 } 369 total_len += offset; /* Without the zero-padding. */ 370 if (offset != 0) { 371 bzero(textdump_block_buffer + offset, 372 sizeof(textdump_block_buffer) - offset); 373 (void)textdump_writenextblock(di, textdump_block_buffer); 374 } 375 376 /* 377 * Rewrite tar header to reflect how much was actually written. 378 */ 379 textdump_saveoff(&end_offset); 380 textdump_restoreoff(tarhdr_offset); 381 textdump_mkustar(textdump_block_buffer, TAR_MSGBUF_FILENAME, 382 total_len); 383 (void)textdump_writenextblock(di, textdump_block_buffer); 384 textdump_restoreoff(end_offset); 385 } 386 387 static void 388 textdump_dump_panic(struct dumperinfo *di) 389 { 390 u_int len; 391 392 /* 393 * Write out tar header -- we store up to one block of panic message. 394 */ 395 len = min(strlen(panicstr), TEXTDUMP_BLOCKSIZE); 396 textdump_mkustar(textdump_block_buffer, TAR_PANIC_FILENAME, len); 397 (void)textdump_writenextblock(di, textdump_block_buffer); 398 399 /* 400 * Zero-pad the panic string and write out block. 401 */ 402 bzero(textdump_block_buffer, sizeof(textdump_block_buffer)); 403 bcopy(panicstr, textdump_block_buffer, len); 404 (void)textdump_writenextblock(di, textdump_block_buffer); 405 } 406 407 static void 408 textdump_dump_version(struct dumperinfo *di) 409 { 410 u_int len; 411 412 /* 413 * Write out tar header -- at most one block of version information. 414 */ 415 len = min(strlen(version), TEXTDUMP_BLOCKSIZE); 416 textdump_mkustar(textdump_block_buffer, TAR_VERSION_FILENAME, len); 417 (void)textdump_writenextblock(di, textdump_block_buffer); 418 419 /* 420 * Zero pad the version string and write out block. 421 */ 422 bzero(textdump_block_buffer, sizeof(textdump_block_buffer)); 423 bcopy(version, textdump_block_buffer, len); 424 (void)textdump_writenextblock(di, textdump_block_buffer); 425 } 426 427 /* 428 * Commit text dump to disk. 429 */ 430 void 431 textdump_dumpsys(struct dumperinfo *di) 432 { 433 struct kerneldumpcrypto *kdc; 434 off_t dumplen, trailer_offset; 435 436 if (di->blocksize != TEXTDUMP_BLOCKSIZE) { 437 printf("Dump partition block size (%ju) not textdump " 438 "block size (%ju)", (uintmax_t)di->blocksize, 439 (uintmax_t)TEXTDUMP_BLOCKSIZE); 440 return; 441 } 442 443 /* 444 * We don't know a priori how large the dump will be, but we do know 445 * that we need to reserve space for metadata and that we need two 446 * dump headers. Also leave room for one ustar header and one block 447 * of data. 448 */ 449 if (di->mediasize < SIZEOF_METADATA + 2 * sizeof(kdh)) { 450 printf("Insufficient space on dump partition for minimal textdump.\n"); 451 return; 452 } 453 textdump_error = 0; 454 455 /* 456 * Disable EKCD because we don't provide encrypted textdumps. 457 */ 458 kdc = di->kdcrypto; 459 di->kdcrypto = NULL; 460 461 /* 462 * Position the start of the dump so that we'll write the kernel dump 463 * trailer immediately before the end of the partition, and then work 464 * our way back. We will rewrite this header later to reflect the 465 * true size if things go well. 466 */ 467 textdump_offset = di->mediasize - sizeof(kdh); 468 textdump_saveoff(&trailer_offset); 469 dump_init_header(di, &kdh, TEXTDUMPMAGIC, KERNELDUMP_TEXT_VERSION, 0); 470 (void)textdump_writenextblock(di, (char *)&kdh); 471 472 /* 473 * Write a series of files in ustar format. 474 */ 475 if (textdump_do_ddb) 476 db_capture_dump(di); 477 #ifdef INCLUDE_CONFIG_FILE 478 if (textdump_do_config) 479 textdump_dump_config(di); 480 #endif 481 if (textdump_do_msgbuf) 482 textdump_dump_msgbuf(di); 483 if (textdump_do_panic && KERNEL_PANICKED()) 484 textdump_dump_panic(di); 485 if (textdump_do_version) 486 textdump_dump_version(di); 487 488 /* 489 * Now that we know the true size, we can write out the header, then 490 * seek back to the end and rewrite the trailer with the correct 491 * size. 492 */ 493 dumplen = trailer_offset - (textdump_offset + TEXTDUMP_BLOCKSIZE); 494 dump_init_header(di, &kdh, TEXTDUMPMAGIC, KERNELDUMP_TEXT_VERSION, 495 dumplen); 496 (void)textdump_writenextblock(di, (char *)&kdh); 497 textdump_restoreoff(trailer_offset); 498 (void)textdump_writenextblock(di, (char *)&kdh); 499 500 /* 501 * Terminate the dump, report any errors, and clear the pending flag. 502 */ 503 if (textdump_error == 0) 504 (void)dump_write(di, NULL, 0, 0); 505 if (textdump_error == ENOSPC) 506 printf("Textdump: Insufficient space on dump partition\n"); 507 else if (textdump_error != 0) 508 printf("Textdump: Error %d writing dump\n", textdump_error); 509 else 510 printf("Textdump complete.\n"); 511 textdump_pending = 0; 512 513 /* 514 * Restore EKCD status. 515 */ 516 di->kdcrypto = kdc; 517 } 518 519 /*- 520 * DDB(4) command to manage textdumps: 521 * 522 * textdump set - request a textdump 523 * textdump status - print DDB output textdump status 524 * textdump unset - clear textdump request 525 */ 526 static void 527 db_textdump_usage(void) 528 { 529 530 db_printf("textdump [unset|set|status|dump]\n"); 531 } 532 533 void 534 db_textdump_cmd(db_expr_t addr, bool have_addr, db_expr_t count, char *modif) 535 { 536 int t; 537 538 t = db_read_token(); 539 if (t != tIDENT) { 540 db_textdump_usage(); 541 return; 542 } 543 if (db_read_token() != tEOL) { 544 db_textdump_usage(); 545 return; 546 } 547 if (strcmp(db_tok_string, "set") == 0) { 548 textdump_pending = 1; 549 db_printf("textdump set\n"); 550 } else if (strcmp(db_tok_string, "status") == 0) { 551 if (textdump_pending) 552 db_printf("textdump is set\n"); 553 else 554 db_printf("textdump is not set\n"); 555 } else if (strcmp(db_tok_string, "unset") == 0) { 556 textdump_pending = 0; 557 db_printf("textdump unset\n"); 558 } else if (strcmp(db_tok_string, "dump") == 0) { 559 textdump_pending = 1; 560 doadump(true); 561 } else { 562 db_textdump_usage(); 563 } 564 } 565