1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 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 #include "opt_config.h" 63 64 #include "opt_ddb.h" 65 66 #include <sys/param.h> 67 #include <sys/conf.h> 68 #include <sys/kernel.h> 69 #include <sys/kerneldump.h> 70 #include <sys/msgbuf.h> 71 #include <sys/sysctl.h> 72 #include <sys/systm.h> 73 74 #include <ddb/ddb.h> 75 #include <ddb/db_lex.h> 76 77 static SYSCTL_NODE(_debug_ddb, OID_AUTO, textdump, 78 CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 79 "DDB textdump options"); 80 81 /* 82 * Don't touch the first SIZEOF_METADATA bytes on the dump device. This is 83 * to protect us from metadata and metadata from us. 84 */ 85 #define SIZEOF_METADATA (64*1024) 86 87 /* 88 * Data is written out as a series of files in the ustar tar format. ustar 89 * is a simple streamed format consiting of a series of files prefixed with 90 * headers, and all padded to 512-byte block boundaries, which maps 91 * conveniently to our requirements. 92 */ 93 struct ustar_header { 94 char uh_filename[100]; 95 char uh_mode[8]; 96 char uh_tar_owner[8]; 97 char uh_tar_group[8]; 98 char uh_size[12]; 99 char uh_mtime[12]; 100 char uh_sum[8]; 101 char uh_type; 102 char uh_linkfile[100]; 103 char uh_ustar[6]; 104 char uh_version[2]; 105 char uh_owner[32]; 106 char uh_group[32]; 107 char uh_major[8]; 108 char uh_minor[8]; 109 char uh_filenameprefix[155]; 110 char uh_zeropad[12]; 111 } __packed; 112 113 /* 114 * Various size assertions -- pretty much everything must be one block in 115 * size. 116 */ 117 CTASSERT(sizeof(struct kerneldumpheader) == TEXTDUMP_BLOCKSIZE); 118 CTASSERT(sizeof(struct ustar_header) == TEXTDUMP_BLOCKSIZE); 119 120 /* 121 * Is a textdump scheduled? If so, the shutdown code will invoke our dumpsys 122 * routine instead of the machine-dependent kernel dump routine. 123 */ 124 #ifdef TEXTDUMP_PREFERRED 125 int textdump_pending = 1; 126 #else 127 int textdump_pending = 0; 128 #endif 129 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, pending, CTLFLAG_RW, 130 &textdump_pending, 0, 131 "Perform textdump instead of regular kernel dump."); 132 133 /* 134 * Various constants for tar headers and contents. 135 */ 136 #define TAR_USER "root" 137 #define TAR_GROUP "wheel" 138 #define TAR_UID "0" 139 #define TAR_GID "0" 140 #define TAR_MODE "0600" 141 #define TAR_USTAR "ustar" 142 143 #define TAR_CONFIG_FILENAME "config.txt" /* Kernel configuration. */ 144 #define TAR_MSGBUF_FILENAME "msgbuf.txt" /* Kernel message buffer. */ 145 #define TAR_PANIC_FILENAME "panic.txt" /* Panic message. */ 146 #define TAR_VERSION_FILENAME "version.txt" /* Kernel version. */ 147 148 /* 149 * Configure which files will be dumped. 150 */ 151 #ifdef INCLUDE_CONFIG_FILE 152 static int textdump_do_config = 1; 153 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_config, CTLFLAG_RW, 154 &textdump_do_config, 0, "Dump kernel configuration in textdump"); 155 #endif 156 157 static int textdump_do_ddb = 1; 158 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_ddb, CTLFLAG_RW, 159 &textdump_do_ddb, 0, "Dump DDB captured output in textdump"); 160 161 static int textdump_do_msgbuf = 1; 162 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_msgbuf, CTLFLAG_RW, 163 &textdump_do_msgbuf, 0, "Dump kernel message buffer in textdump"); 164 165 static int textdump_do_panic = 1; 166 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_panic, CTLFLAG_RW, 167 &textdump_do_panic, 0, "Dump kernel panic message in textdump"); 168 169 static int textdump_do_version = 1; 170 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_version, CTLFLAG_RW, 171 &textdump_do_version, 0, "Dump kernel version string in textdump"); 172 173 /* 174 * State related to incremental writing of blocks to disk. 175 */ 176 static off_t textdump_offset; /* Offset of next sequential write. */ 177 static int textdump_error; /* Carried write error, if any. */ 178 179 /* 180 * Statically allocate space to prepare block-sized headers and data. 181 */ 182 char textdump_block_buffer[TEXTDUMP_BLOCKSIZE]; 183 static struct kerneldumpheader kdh; 184 185 /* 186 * Calculate and fill in the checksum for a ustar header. 187 */ 188 static void 189 ustar_checksum(struct ustar_header *uhp) 190 { 191 u_int sum; 192 int i; 193 194 for (i = 0; i < sizeof(uhp->uh_sum); i++) 195 uhp->uh_sum[i] = ' '; 196 sum = 0; 197 for (i = 0; i < sizeof(*uhp); i++) 198 sum += ((u_char *)uhp)[i]; 199 snprintf(uhp->uh_sum, sizeof(uhp->uh_sum), "%6o", sum); 200 } 201 202 /* 203 * Each file in the tarball has a block-sized header with its name and other, 204 * largely hard-coded, properties. 205 */ 206 void 207 textdump_mkustar(char *block_buffer, const char *filename, u_int size) 208 { 209 struct ustar_header *uhp; 210 211 #ifdef TEXTDUMP_VERBOSE 212 if (textdump_error == 0) 213 printf("textdump: creating '%s'.\n", filename); 214 #endif 215 uhp = (struct ustar_header *)block_buffer; 216 bzero(uhp, sizeof(*uhp)); 217 strlcpy(uhp->uh_filename, filename, sizeof(uhp->uh_filename)); 218 strlcpy(uhp->uh_mode, TAR_MODE, sizeof(uhp->uh_mode)); 219 snprintf(uhp->uh_size, sizeof(uhp->uh_size), "%o", size); 220 strlcpy(uhp->uh_tar_owner, TAR_UID, sizeof(uhp->uh_tar_owner)); 221 strlcpy(uhp->uh_tar_group, TAR_GID, sizeof(uhp->uh_tar_group)); 222 strlcpy(uhp->uh_owner, TAR_USER, sizeof(uhp->uh_owner)); 223 strlcpy(uhp->uh_group, TAR_GROUP, sizeof(uhp->uh_group)); 224 snprintf(uhp->uh_mtime, sizeof(uhp->uh_mtime), "%lo", 225 (unsigned long)time_second); 226 uhp->uh_type = 0; 227 strlcpy(uhp->uh_ustar, TAR_USTAR, sizeof(uhp->uh_ustar)); 228 ustar_checksum(uhp); 229 } 230 231 /* 232 * textdump_writeblock() writes TEXTDUMP_BLOCKSIZE-sized blocks of data to 233 * the space between di->mediaoffset and di->mediaoffset + di->mediasize. It 234 * accepts an offset relative to di->mediaoffset. If we're carrying any 235 * error from previous I/O, return that error and don't continue to try to 236 * write. Most writers ignore the error and forge ahead on the basis that 237 * there's not much you can do. 238 */ 239 static int 240 textdump_writeblock(struct dumperinfo *di, off_t offset, char *buffer) 241 { 242 243 if (textdump_error) 244 return (textdump_error); 245 if (offset + TEXTDUMP_BLOCKSIZE > di->mediasize) 246 return (EIO); 247 if (offset < SIZEOF_METADATA) 248 return (ENOSPC); 249 textdump_error = dump_write(di, buffer, offset + di->mediaoffset, 250 TEXTDUMP_BLOCKSIZE); 251 if (textdump_error) 252 printf("textdump_writeblock: offset %jd, error %d\n", (intmax_t)offset, 253 textdump_error); 254 return (textdump_error); 255 } 256 257 /* 258 * Interfaces to save and restore the dump offset, so that printers can go 259 * back to rewrite a header if required, while avoiding their knowing about 260 * the global layout of the blocks. 261 * 262 * If we ever want to support writing textdumps to tape or other 263 * stream-oriented target, we'll need to remove this. 264 */ 265 void 266 textdump_saveoff(off_t *offsetp) 267 { 268 269 *offsetp = textdump_offset; 270 } 271 272 void 273 textdump_restoreoff(off_t offset) 274 { 275 276 textdump_offset = offset; 277 } 278 279 /* 280 * Interface to write the "next block" relative to the current offset; since 281 * we write backwards from the end of the partition, we subtract, but there's 282 * no reason for the caller to know this. 283 */ 284 int 285 textdump_writenextblock(struct dumperinfo *di, char *buffer) 286 { 287 int error; 288 289 error = textdump_writeblock(di, textdump_offset, buffer); 290 textdump_offset -= TEXTDUMP_BLOCKSIZE; 291 return (error); 292 } 293 294 #ifdef INCLUDE_CONFIG_FILE 295 extern char kernconfstring[]; 296 297 /* 298 * Dump kernel configuration. 299 */ 300 static void 301 textdump_dump_config(struct dumperinfo *di) 302 { 303 u_int count, fullblocks, len; 304 305 len = strlen(kernconfstring); 306 textdump_mkustar(textdump_block_buffer, TAR_CONFIG_FILENAME, len); 307 (void)textdump_writenextblock(di, textdump_block_buffer); 308 309 /* 310 * Write out all full blocks directly from the string, and handle any 311 * left-over bits by copying it to out to the local buffer and 312 * zero-padding it. 313 */ 314 fullblocks = len / TEXTDUMP_BLOCKSIZE; 315 for (count = 0; count < fullblocks; count++) 316 (void)textdump_writenextblock(di, kernconfstring + count * 317 TEXTDUMP_BLOCKSIZE); 318 if (len % TEXTDUMP_BLOCKSIZE != 0) { 319 bzero(textdump_block_buffer, TEXTDUMP_BLOCKSIZE); 320 bcopy(kernconfstring + count * TEXTDUMP_BLOCKSIZE, 321 textdump_block_buffer, len % TEXTDUMP_BLOCKSIZE); 322 (void)textdump_writenextblock(di, textdump_block_buffer); 323 } 324 } 325 #endif /* INCLUDE_CONFIG_FILE */ 326 327 /* 328 * Dump kernel message buffer. 329 */ 330 static void 331 textdump_dump_msgbuf(struct dumperinfo *di) 332 { 333 off_t end_offset, tarhdr_offset; 334 u_int i, len, offset, seq, total_len; 335 char buf[16]; 336 337 /* 338 * Write out a dummy tar header to advance the offset; we'll rewrite 339 * it later once we know the true size. 340 */ 341 textdump_saveoff(&tarhdr_offset); 342 textdump_mkustar(textdump_block_buffer, TAR_MSGBUF_FILENAME, 0); 343 (void)textdump_writenextblock(di, textdump_block_buffer); 344 345 /* 346 * Copy out the data in small chunks, but don't copy nuls that may be 347 * present if the message buffer has not yet completely filled at 348 * least once. 349 */ 350 total_len = 0; 351 offset = 0; 352 msgbuf_peekbytes(msgbufp, NULL, 0, &seq); 353 while ((len = msgbuf_peekbytes(msgbufp, buf, sizeof(buf), &seq)) > 0) { 354 for (i = 0; i < len; i++) { 355 if (buf[i] == '\0') 356 continue; 357 textdump_block_buffer[offset] = buf[i]; 358 offset++; 359 if (offset != sizeof(textdump_block_buffer)) 360 continue; 361 (void)textdump_writenextblock(di, 362 textdump_block_buffer); 363 total_len += offset; 364 offset = 0; 365 } 366 } 367 total_len += offset; /* Without the zero-padding. */ 368 if (offset != 0) { 369 bzero(textdump_block_buffer + offset, 370 sizeof(textdump_block_buffer) - offset); 371 (void)textdump_writenextblock(di, textdump_block_buffer); 372 } 373 374 /* 375 * Rewrite tar header to reflect how much was actually written. 376 */ 377 textdump_saveoff(&end_offset); 378 textdump_restoreoff(tarhdr_offset); 379 textdump_mkustar(textdump_block_buffer, TAR_MSGBUF_FILENAME, 380 total_len); 381 (void)textdump_writenextblock(di, textdump_block_buffer); 382 textdump_restoreoff(end_offset); 383 } 384 385 static void 386 textdump_dump_panic(struct dumperinfo *di) 387 { 388 u_int len; 389 390 /* 391 * Write out tar header -- we store up to one block of panic message. 392 */ 393 len = min(strlen(panicstr), TEXTDUMP_BLOCKSIZE); 394 textdump_mkustar(textdump_block_buffer, TAR_PANIC_FILENAME, len); 395 (void)textdump_writenextblock(di, textdump_block_buffer); 396 397 /* 398 * Zero-pad the panic string and write out block. 399 */ 400 bzero(textdump_block_buffer, sizeof(textdump_block_buffer)); 401 bcopy(panicstr, textdump_block_buffer, len); 402 (void)textdump_writenextblock(di, textdump_block_buffer); 403 } 404 405 static void 406 textdump_dump_version(struct dumperinfo *di) 407 { 408 u_int len; 409 410 /* 411 * Write out tar header -- at most one block of version information. 412 */ 413 len = min(strlen(version), TEXTDUMP_BLOCKSIZE); 414 textdump_mkustar(textdump_block_buffer, TAR_VERSION_FILENAME, len); 415 (void)textdump_writenextblock(di, textdump_block_buffer); 416 417 /* 418 * Zero pad the version string and write out block. 419 */ 420 bzero(textdump_block_buffer, sizeof(textdump_block_buffer)); 421 bcopy(version, textdump_block_buffer, len); 422 (void)textdump_writenextblock(di, textdump_block_buffer); 423 } 424 425 /* 426 * Commit text dump to disk. 427 */ 428 void 429 textdump_dumpsys(struct dumperinfo *di) 430 { 431 struct kerneldumpcrypto *kdc; 432 off_t dumplen, trailer_offset; 433 434 if (di->blocksize != TEXTDUMP_BLOCKSIZE) { 435 printf("Dump partition block size (%ju) not textdump " 436 "block size (%ju)", (uintmax_t)di->blocksize, 437 (uintmax_t)TEXTDUMP_BLOCKSIZE); 438 return; 439 } 440 441 /* 442 * We don't know a priori how large the dump will be, but we do know 443 * that we need to reserve space for metadata and that we need two 444 * dump headers. Also leave room for one ustar header and one block 445 * of data. 446 */ 447 if (di->mediasize < SIZEOF_METADATA + 2 * sizeof(kdh)) { 448 printf("Insufficient space on dump partition for minimal textdump.\n"); 449 return; 450 } 451 textdump_error = 0; 452 453 /* 454 * Disable EKCD because we don't provide encrypted textdumps. 455 */ 456 kdc = di->kdcrypto; 457 di->kdcrypto = NULL; 458 459 /* 460 * Position the start of the dump so that we'll write the kernel dump 461 * trailer immediately before the end of the partition, and then work 462 * our way back. We will rewrite this header later to reflect the 463 * true size if things go well. 464 */ 465 textdump_offset = di->mediasize - sizeof(kdh); 466 textdump_saveoff(&trailer_offset); 467 dump_init_header(di, &kdh, TEXTDUMPMAGIC, KERNELDUMP_TEXT_VERSION, 0); 468 (void)textdump_writenextblock(di, (char *)&kdh); 469 470 /* 471 * Write a series of files in ustar format. 472 */ 473 if (textdump_do_ddb) 474 db_capture_dump(di); 475 #ifdef INCLUDE_CONFIG_FILE 476 if (textdump_do_config) 477 textdump_dump_config(di); 478 #endif 479 if (textdump_do_msgbuf) 480 textdump_dump_msgbuf(di); 481 if (textdump_do_panic && KERNEL_PANICKED()) 482 textdump_dump_panic(di); 483 if (textdump_do_version) 484 textdump_dump_version(di); 485 486 /* 487 * Now that we know the true size, we can write out the header, then 488 * seek back to the end and rewrite the trailer with the correct 489 * size. 490 */ 491 dumplen = trailer_offset - (textdump_offset + TEXTDUMP_BLOCKSIZE); 492 dump_init_header(di, &kdh, TEXTDUMPMAGIC, KERNELDUMP_TEXT_VERSION, 493 dumplen); 494 (void)textdump_writenextblock(di, (char *)&kdh); 495 textdump_restoreoff(trailer_offset); 496 (void)textdump_writenextblock(di, (char *)&kdh); 497 498 /* 499 * Terminate the dump, report any errors, and clear the pending flag. 500 */ 501 if (textdump_error == 0) 502 (void)dump_write(di, NULL, 0, 0); 503 if (textdump_error == ENOSPC) 504 printf("Textdump: Insufficient space on dump partition\n"); 505 else if (textdump_error != 0) 506 printf("Textdump: Error %d writing dump\n", textdump_error); 507 else 508 printf("Textdump complete.\n"); 509 textdump_pending = 0; 510 511 /* 512 * Restore EKCD status. 513 */ 514 di->kdcrypto = kdc; 515 } 516 517 /*- 518 * DDB(4) command to manage textdumps: 519 * 520 * textdump set - request a textdump 521 * textdump status - print DDB output textdump status 522 * textdump unset - clear textdump request 523 */ 524 static void 525 db_textdump_usage(void) 526 { 527 528 db_printf("textdump [unset|set|status|dump]\n"); 529 } 530 531 void 532 db_textdump_cmd(db_expr_t addr, bool have_addr, db_expr_t count, 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 if (strcmp(db_tok_string, "dump") == 0) { 557 textdump_pending = 1; 558 doadump(true); 559 } else { 560 db_textdump_usage(); 561 } 562 } 563