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, CTLFLAG_RW, 0, 80 "DDB textdump options"); 81 82 /* 83 * Don't touch the first SIZEOF_METADATA bytes on the dump device. This is 84 * to protect us from metadata and metadata from us. 85 */ 86 #define SIZEOF_METADATA (64*1024) 87 88 /* 89 * Data is written out as a series of files in the ustar tar format. ustar 90 * is a simple streamed format consiting of a series of files prefixed with 91 * headers, and all padded to 512-byte block boundaries, which maps 92 * conveniently to our requirements. 93 */ 94 struct ustar_header { 95 char uh_filename[100]; 96 char uh_mode[8]; 97 char uh_tar_owner[8]; 98 char uh_tar_group[8]; 99 char uh_size[12]; 100 char uh_mtime[12]; 101 char uh_sum[8]; 102 char uh_type; 103 char uh_linkfile[100]; 104 char uh_ustar[6]; 105 char uh_version[2]; 106 char uh_owner[32]; 107 char uh_group[32]; 108 char uh_major[8]; 109 char uh_minor[8]; 110 char uh_filenameprefix[155]; 111 char uh_zeropad[12]; 112 } __packed; 113 114 /* 115 * Various size assertions -- pretty much everything must be one block in 116 * size. 117 */ 118 CTASSERT(sizeof(struct kerneldumpheader) == TEXTDUMP_BLOCKSIZE); 119 CTASSERT(sizeof(struct ustar_header) == TEXTDUMP_BLOCKSIZE); 120 121 /* 122 * Is a textdump scheduled? If so, the shutdown code will invoke our dumpsys 123 * routine instead of the machine-dependent kernel dump routine. 124 */ 125 #ifdef TEXTDUMP_PREFERRED 126 int textdump_pending = 1; 127 #else 128 int textdump_pending = 0; 129 #endif 130 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, pending, CTLFLAG_RW, 131 &textdump_pending, 0, 132 "Perform textdump instead of regular kernel dump."); 133 134 /* 135 * Various constants for tar headers and contents. 136 */ 137 #define TAR_USER "root" 138 #define TAR_GROUP "wheel" 139 #define TAR_UID "0" 140 #define TAR_GID "0" 141 #define TAR_MODE "0600" 142 #define TAR_USTAR "ustar" 143 144 #define TAR_CONFIG_FILENAME "config.txt" /* Kernel configuration. */ 145 #define TAR_MSGBUF_FILENAME "msgbuf.txt" /* Kernel messsage buffer. */ 146 #define TAR_PANIC_FILENAME "panic.txt" /* Panic message. */ 147 #define TAR_VERSION_FILENAME "version.txt" /* Kernel version. */ 148 149 /* 150 * Configure which files will be dumped. 151 */ 152 #ifdef INCLUDE_CONFIG_FILE 153 static int textdump_do_config = 1; 154 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_config, CTLFLAG_RW, 155 &textdump_do_config, 0, "Dump kernel configuration in textdump"); 156 #endif 157 158 static int textdump_do_ddb = 1; 159 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_ddb, CTLFLAG_RW, 160 &textdump_do_ddb, 0, "Dump DDB captured output in textdump"); 161 162 static int textdump_do_msgbuf = 1; 163 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_msgbuf, CTLFLAG_RW, 164 &textdump_do_msgbuf, 0, "Dump kernel message buffer in textdump"); 165 166 static int textdump_do_panic = 1; 167 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_panic, CTLFLAG_RW, 168 &textdump_do_panic, 0, "Dump kernel panic message in textdump"); 169 170 static int textdump_do_version = 1; 171 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_version, CTLFLAG_RW, 172 &textdump_do_version, 0, "Dump kernel version string in textdump"); 173 174 /* 175 * State related to incremental writing of blocks to disk. 176 */ 177 static off_t textdump_offset; /* Offset of next sequential write. */ 178 static int textdump_error; /* Carried write error, if any. */ 179 180 /* 181 * Statically allocate space to prepare block-sized headers and data. 182 */ 183 char textdump_block_buffer[TEXTDUMP_BLOCKSIZE]; 184 static struct kerneldumpheader kdh; 185 186 /* 187 * Calculate and fill in the checksum for a ustar header. 188 */ 189 static void 190 ustar_checksum(struct ustar_header *uhp) 191 { 192 u_int sum; 193 int i; 194 195 for (i = 0; i < sizeof(uhp->uh_sum); i++) 196 uhp->uh_sum[i] = ' '; 197 sum = 0; 198 for (i = 0; i < sizeof(*uhp); i++) 199 sum += ((u_char *)uhp)[i]; 200 snprintf(uhp->uh_sum, sizeof(uhp->uh_sum), "%6o", sum); 201 } 202 203 /* 204 * Each file in the tarball has a block-sized header with its name and other, 205 * largely hard-coded, properties. 206 */ 207 void 208 textdump_mkustar(char *block_buffer, const char *filename, u_int size) 209 { 210 struct ustar_header *uhp; 211 212 #ifdef TEXTDUMP_VERBOSE 213 if (textdump_error == 0) 214 printf("textdump: creating '%s'.\n", filename); 215 #endif 216 uhp = (struct ustar_header *)block_buffer; 217 bzero(uhp, sizeof(*uhp)); 218 strlcpy(uhp->uh_filename, filename, sizeof(uhp->uh_filename)); 219 strlcpy(uhp->uh_mode, TAR_MODE, sizeof(uhp->uh_mode)); 220 snprintf(uhp->uh_size, sizeof(uhp->uh_size), "%o", size); 221 strlcpy(uhp->uh_tar_owner, TAR_UID, sizeof(uhp->uh_tar_owner)); 222 strlcpy(uhp->uh_tar_group, TAR_GID, sizeof(uhp->uh_tar_group)); 223 strlcpy(uhp->uh_owner, TAR_USER, sizeof(uhp->uh_owner)); 224 strlcpy(uhp->uh_group, TAR_GROUP, sizeof(uhp->uh_group)); 225 snprintf(uhp->uh_mtime, sizeof(uhp->uh_mtime), "%lo", 226 (unsigned long)time_second); 227 uhp->uh_type = 0; 228 strlcpy(uhp->uh_ustar, TAR_USTAR, sizeof(uhp->uh_ustar)); 229 ustar_checksum(uhp); 230 } 231 232 /* 233 * textdump_writeblock() writes TEXTDUMP_BLOCKSIZE-sized blocks of data to 234 * the space between di->mediaoffset and di->mediaoffset + di->mediasize. It 235 * accepts an offset relative to di->mediaoffset. If we're carrying any 236 * error from previous I/O, return that error and don't continue to try to 237 * write. Most writers ignore the error and forge ahead on the basis that 238 * there's not much you can do. 239 */ 240 static int 241 textdump_writeblock(struct dumperinfo *di, off_t offset, char *buffer) 242 { 243 244 if (textdump_error) 245 return (textdump_error); 246 if (offset + TEXTDUMP_BLOCKSIZE > di->mediasize) 247 return (EIO); 248 if (offset < SIZEOF_METADATA) 249 return (ENOSPC); 250 textdump_error = dump_write(di, buffer, 0, offset + di->mediaoffset, 251 TEXTDUMP_BLOCKSIZE); 252 if (textdump_error) 253 printf("textdump_writeblock: offset %jd, error %d\n", (intmax_t)offset, 254 textdump_error); 255 return (textdump_error); 256 } 257 258 /* 259 * Interfaces to save and restore the dump offset, so that printers can go 260 * back to rewrite a header if required, while avoiding their knowing about 261 * the global layout of the blocks. 262 * 263 * If we ever want to support writing textdumps to tape or other 264 * stream-oriented target, we'll need to remove this. 265 */ 266 void 267 textdump_saveoff(off_t *offsetp) 268 { 269 270 *offsetp = textdump_offset; 271 } 272 273 void 274 textdump_restoreoff(off_t offset) 275 { 276 277 textdump_offset = offset; 278 } 279 280 /* 281 * Interface to write the "next block" relative to the current offset; since 282 * we write backwards from the end of the partition, we subtract, but there's 283 * no reason for the caller to know this. 284 */ 285 int 286 textdump_writenextblock(struct dumperinfo *di, char *buffer) 287 { 288 int error; 289 290 error = textdump_writeblock(di, textdump_offset, buffer); 291 textdump_offset -= TEXTDUMP_BLOCKSIZE; 292 return (error); 293 } 294 295 #ifdef INCLUDE_CONFIG_FILE 296 extern char kernconfstring[]; 297 298 /* 299 * Dump kernel configuration. 300 */ 301 static void 302 textdump_dump_config(struct dumperinfo *di) 303 { 304 u_int count, fullblocks, len; 305 306 len = strlen(kernconfstring); 307 textdump_mkustar(textdump_block_buffer, TAR_CONFIG_FILENAME, len); 308 (void)textdump_writenextblock(di, textdump_block_buffer); 309 310 /* 311 * Write out all full blocks directly from the string, and handle any 312 * left-over bits by copying it to out to the local buffer and 313 * zero-padding it. 314 */ 315 fullblocks = len / TEXTDUMP_BLOCKSIZE; 316 for (count = 0; count < fullblocks; count++) 317 (void)textdump_writenextblock(di, kernconfstring + count * 318 TEXTDUMP_BLOCKSIZE); 319 if (len % TEXTDUMP_BLOCKSIZE != 0) { 320 bzero(textdump_block_buffer, TEXTDUMP_BLOCKSIZE); 321 bcopy(kernconfstring + count * TEXTDUMP_BLOCKSIZE, 322 textdump_block_buffer, len % TEXTDUMP_BLOCKSIZE); 323 (void)textdump_writenextblock(di, textdump_block_buffer); 324 } 325 } 326 #endif /* INCLUDE_CONFIG_FILE */ 327 328 /* 329 * Dump kernel message buffer. 330 */ 331 static void 332 textdump_dump_msgbuf(struct dumperinfo *di) 333 { 334 off_t end_offset, tarhdr_offset; 335 u_int i, len, offset, seq, total_len; 336 char buf[16]; 337 338 /* 339 * Write out a dummy tar header to advance the offset; we'll rewrite 340 * it later once we know the true size. 341 */ 342 textdump_saveoff(&tarhdr_offset); 343 textdump_mkustar(textdump_block_buffer, TAR_MSGBUF_FILENAME, 0); 344 (void)textdump_writenextblock(di, textdump_block_buffer); 345 346 /* 347 * Copy out the data in small chunks, but don't copy nuls that may be 348 * present if the message buffer has not yet completely filled at 349 * least once. 350 */ 351 total_len = 0; 352 offset = 0; 353 msgbuf_peekbytes(msgbufp, NULL, 0, &seq); 354 while ((len = msgbuf_peekbytes(msgbufp, buf, sizeof(buf), &seq)) > 0) { 355 for (i = 0; i < len; i++) { 356 if (buf[i] == '\0') 357 continue; 358 textdump_block_buffer[offset] = buf[i]; 359 offset++; 360 if (offset != sizeof(textdump_block_buffer)) 361 continue; 362 (void)textdump_writenextblock(di, 363 textdump_block_buffer); 364 total_len += offset; 365 offset = 0; 366 } 367 } 368 total_len += offset; /* Without the zero-padding. */ 369 if (offset != 0) { 370 bzero(textdump_block_buffer + offset, 371 sizeof(textdump_block_buffer) - offset); 372 (void)textdump_writenextblock(di, textdump_block_buffer); 373 } 374 375 /* 376 * Rewrite tar header to reflect how much was actually written. 377 */ 378 textdump_saveoff(&end_offset); 379 textdump_restoreoff(tarhdr_offset); 380 textdump_mkustar(textdump_block_buffer, TAR_MSGBUF_FILENAME, 381 total_len); 382 (void)textdump_writenextblock(di, textdump_block_buffer); 383 textdump_restoreoff(end_offset); 384 } 385 386 static void 387 textdump_dump_panic(struct dumperinfo *di) 388 { 389 u_int len; 390 391 /* 392 * Write out tar header -- we store up to one block of panic message. 393 */ 394 len = min(strlen(panicstr), TEXTDUMP_BLOCKSIZE); 395 textdump_mkustar(textdump_block_buffer, TAR_PANIC_FILENAME, len); 396 (void)textdump_writenextblock(di, textdump_block_buffer); 397 398 /* 399 * Zero-pad the panic string and write out block. 400 */ 401 bzero(textdump_block_buffer, sizeof(textdump_block_buffer)); 402 bcopy(panicstr, textdump_block_buffer, len); 403 (void)textdump_writenextblock(di, textdump_block_buffer); 404 } 405 406 static void 407 textdump_dump_version(struct dumperinfo *di) 408 { 409 u_int len; 410 411 /* 412 * Write out tar header -- at most one block of version information. 413 */ 414 len = min(strlen(version), TEXTDUMP_BLOCKSIZE); 415 textdump_mkustar(textdump_block_buffer, TAR_VERSION_FILENAME, len); 416 (void)textdump_writenextblock(di, textdump_block_buffer); 417 418 /* 419 * Zero pad the version string and write out block. 420 */ 421 bzero(textdump_block_buffer, sizeof(textdump_block_buffer)); 422 bcopy(version, textdump_block_buffer, len); 423 (void)textdump_writenextblock(di, textdump_block_buffer); 424 } 425 426 /* 427 * Commit text dump to disk. 428 */ 429 void 430 textdump_dumpsys(struct dumperinfo *di) 431 { 432 struct kerneldumpcrypto *kdc; 433 off_t dumplen, trailer_offset; 434 435 if (di->blocksize != TEXTDUMP_BLOCKSIZE) { 436 printf("Dump partition block size (%ju) not textdump " 437 "block size (%ju)", (uintmax_t)di->blocksize, 438 (uintmax_t)TEXTDUMP_BLOCKSIZE); 439 return; 440 } 441 442 /* 443 * We don't know a priori how large the dump will be, but we do know 444 * that we need to reserve space for metadata and that we need two 445 * dump headers. Also leave room for one ustar header and one block 446 * of data. 447 */ 448 if (di->mediasize < SIZEOF_METADATA + 2 * sizeof(kdh)) { 449 printf("Insufficient space on dump partition for minimal textdump.\n"); 450 return; 451 } 452 textdump_error = 0; 453 454 /* 455 * Disable EKCD because we don't provide encrypted textdumps. 456 */ 457 kdc = di->kdcrypto; 458 di->kdcrypto = NULL; 459 460 /* 461 * Position the start of the dump so that we'll write the kernel dump 462 * trailer immediately before the end of the partition, and then work 463 * our way back. We will rewrite this header later to reflect the 464 * true size if things go well. 465 */ 466 textdump_offset = di->mediasize - sizeof(kdh); 467 textdump_saveoff(&trailer_offset); 468 dump_init_header(di, &kdh, TEXTDUMPMAGIC, KERNELDUMP_TEXT_VERSION, 0); 469 (void)textdump_writenextblock(di, (char *)&kdh); 470 471 /* 472 * Write a series of files in ustar format. 473 */ 474 if (textdump_do_ddb) 475 db_capture_dump(di); 476 #ifdef INCLUDE_CONFIG_FILE 477 if (textdump_do_config) 478 textdump_dump_config(di); 479 #endif 480 if (textdump_do_msgbuf) 481 textdump_dump_msgbuf(di); 482 if (textdump_do_panic && panicstr != NULL) 483 textdump_dump_panic(di); 484 if (textdump_do_version) 485 textdump_dump_version(di); 486 487 /* 488 * Now that we know the true size, we can write out the header, then 489 * seek back to the end and rewrite the trailer with the correct 490 * size. 491 */ 492 dumplen = trailer_offset - (textdump_offset + TEXTDUMP_BLOCKSIZE); 493 dump_init_header(di, &kdh, TEXTDUMPMAGIC, KERNELDUMP_TEXT_VERSION, 494 dumplen); 495 (void)textdump_writenextblock(di, (char *)&kdh); 496 textdump_restoreoff(trailer_offset); 497 (void)textdump_writenextblock(di, (char *)&kdh); 498 499 /* 500 * Terminate the dump, report any errors, and clear the pending flag. 501 */ 502 if (textdump_error == 0) 503 (void)dump_write(di, NULL, 0, 0, 0); 504 if (textdump_error == ENOSPC) 505 printf("Textdump: Insufficient space on dump partition\n"); 506 else if (textdump_error != 0) 507 printf("Textdump: Error %d writing dump\n", textdump_error); 508 else 509 printf("Textdump complete.\n"); 510 textdump_pending = 0; 511 512 /* 513 * Restore EKCD status. 514 */ 515 di->kdcrypto = kdc; 516 } 517 518 /*- 519 * DDB(4) command to manage textdumps: 520 * 521 * textdump set - request a textdump 522 * textdump status - print DDB output textdump status 523 * textdump unset - clear textdump request 524 */ 525 static void 526 db_textdump_usage(void) 527 { 528 529 db_printf("textdump [unset|set|status|dump]\n"); 530 } 531 532 void 533 db_textdump_cmd(db_expr_t addr, bool have_addr, db_expr_t count, char *modif) 534 { 535 int t; 536 537 t = db_read_token(); 538 if (t != tIDENT) { 539 db_textdump_usage(); 540 return; 541 } 542 if (db_read_token() != tEOL) { 543 db_textdump_usage(); 544 return; 545 } 546 if (strcmp(db_tok_string, "set") == 0) { 547 textdump_pending = 1; 548 db_printf("textdump set\n"); 549 } else if (strcmp(db_tok_string, "status") == 0) { 550 if (textdump_pending) 551 db_printf("textdump is set\n"); 552 else 553 db_printf("textdump is not set\n"); 554 } else if (strcmp(db_tok_string, "unset") == 0) { 555 textdump_pending = 0; 556 db_printf("textdump unset\n"); 557 } else if (strcmp(db_tok_string, "dump") == 0) { 558 textdump_pending = 1; 559 doadump(true); 560 } else { 561 db_textdump_usage(); 562 } 563 } 564