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