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 * Calculate and fill in the checksum for a ustar header. 181 */ 182 static void 183 ustar_checksum(struct ustar_header *uhp) 184 { 185 u_int sum; 186 int i; 187 188 for (i = 0; i < sizeof(uhp->uh_sum); i++) 189 uhp->uh_sum[i] = ' '; 190 sum = 0; 191 for (i = 0; i < sizeof(*uhp); i++) 192 sum += ((u_char *)uhp)[i]; 193 snprintf(uhp->uh_sum, sizeof(uhp->uh_sum), "%6o", sum); 194 } 195 196 /* 197 * Each file in the tarball has a block-sized header with its name and other, 198 * largely hard-coded, properties. 199 */ 200 void 201 textdump_mkustar(char *block_buffer, const char *filename, u_int size) 202 { 203 struct ustar_header *uhp; 204 205 uhp = (struct ustar_header *)block_buffer; 206 bzero(uhp, sizeof(*uhp)); 207 strlcpy(uhp->uh_filename, filename, sizeof(uhp->uh_filename)); 208 strlcpy(uhp->uh_mode, TAR_MODE, sizeof(uhp->uh_mode)); 209 snprintf(uhp->uh_size, sizeof(uhp->uh_size), "%o", size); 210 strlcpy(uhp->uh_tar_owner, TAR_UID, sizeof(uhp->uh_tar_owner)); 211 strlcpy(uhp->uh_tar_group, TAR_GID, sizeof(uhp->uh_tar_group)); 212 strlcpy(uhp->uh_owner, TAR_USER, sizeof(uhp->uh_owner)); 213 strlcpy(uhp->uh_group, TAR_GROUP, sizeof(uhp->uh_group)); 214 snprintf(uhp->uh_mtime, sizeof(uhp->uh_mtime), "%lo", 215 (unsigned long)time_second); 216 uhp->uh_type = 0; 217 strlcpy(uhp->uh_ustar, TAR_USTAR, sizeof(uhp->uh_ustar)); 218 ustar_checksum(uhp); 219 } 220 221 /* 222 * textdump_writeblock() writes TEXTDUMP_BLOCKSIZE-sized blocks of data to 223 * the space between di->mediaoffset and di->mediaoffset + di->mediasize. It 224 * accepts an offset relative to di->mediaoffset. If we're carrying any 225 * error from previous I/O, return that error and don't continue to try to 226 * write. Most writers ignore the error and forge ahead on the basis that 227 * there's not much you can do. 228 */ 229 static int 230 textdump_writeblock(struct dumperinfo *di, off_t offset, char *buffer) 231 { 232 233 if (textdump_error) 234 return (textdump_error); 235 if (offset + TEXTDUMP_BLOCKSIZE > di->mediasize) 236 return (EIO); 237 if (offset < SIZEOF_METADATA) 238 return (ENOSPC); 239 textdump_error = dump_write(di, buffer, 0, offset + di->mediaoffset, 240 TEXTDUMP_BLOCKSIZE); 241 return (textdump_error); 242 } 243 244 /* 245 * Interfaces to save and restore the dump offset, so that printers can go 246 * back to rewrite a header if required, while avoiding their knowing about 247 * the global layout of the blocks. 248 * 249 * If we ever want to support writing textdumps to tape or other 250 * stream-oriented target, we'll need to remove this. 251 */ 252 void 253 textdump_saveoff(off_t *offsetp) 254 { 255 256 *offsetp = textdump_offset; 257 } 258 259 void 260 textdump_restoreoff(off_t offset) 261 { 262 263 textdump_offset = offset; 264 } 265 266 /* 267 * Interface to write the "next block" relative to the current offset; since 268 * we write backwards from the end of the partition, we subtract, but there's 269 * no reason for the caller to know this. 270 */ 271 int 272 textdump_writenextblock(struct dumperinfo *di, char *buffer) 273 { 274 int error; 275 276 error = textdump_writeblock(di, textdump_offset, buffer); 277 textdump_offset -= TEXTDUMP_BLOCKSIZE; 278 return (error); 279 } 280 281 #ifdef INCLUDE_CONFIG_FILE 282 extern char kernconfstring[]; 283 284 /* 285 * Dump kernel configuration. 286 */ 287 static void 288 textdump_dump_config(struct dumperinfo *di) 289 { 290 u_int count, fullblocks, len; 291 292 len = strlen(kernconfstring); 293 textdump_mkustar(textdump_block_buffer, TAR_CONFIG_FILENAME, len); 294 (void)textdump_writenextblock(di, textdump_block_buffer); 295 296 /* 297 * Write out all full blocks directly from the string, and handle any 298 * left-over bits by copying it to out to the local buffer and 299 * zero-padding it. 300 */ 301 fullblocks = len / TEXTDUMP_BLOCKSIZE; 302 for (count = 0; count < fullblocks; count++) 303 (void)textdump_writenextblock(di, kernconfstring + count * 304 TEXTDUMP_BLOCKSIZE); 305 if (len % TEXTDUMP_BLOCKSIZE != 0) { 306 bzero(textdump_block_buffer, TEXTDUMP_BLOCKSIZE); 307 bcopy(kernconfstring + count * TEXTDUMP_BLOCKSIZE, 308 textdump_block_buffer, len % TEXTDUMP_BLOCKSIZE); 309 (void)textdump_writenextblock(di, textdump_block_buffer); 310 } 311 } 312 #endif /* INCLUDE_CONFIG_FILE */ 313 314 /* 315 * Dump kernel message buffer. 316 */ 317 static void 318 textdump_dump_msgbuf(struct dumperinfo *di) 319 { 320 off_t end_offset, tarhdr_offset; 321 u_int i, len, offset, seq, total_len; 322 char buf[16]; 323 324 /* 325 * Write out a dummy tar header to advance the offset; we'll rewrite 326 * it later once we know the true size. 327 */ 328 textdump_saveoff(&tarhdr_offset); 329 textdump_mkustar(textdump_block_buffer, TAR_MSGBUF_FILENAME, 0); 330 (void)textdump_writenextblock(di, textdump_block_buffer); 331 332 /* 333 * Copy out the data in small chunks, but don't copy nuls that may be 334 * present if the message buffer has not yet completely filled at 335 * least once. 336 */ 337 total_len = 0; 338 offset = 0; 339 msgbuf_peekbytes(msgbufp, NULL, 0, &seq); 340 while ((len = msgbuf_peekbytes(msgbufp, buf, sizeof(buf), &seq)) > 0) { 341 for (i = 0; i < len; i++) { 342 if (buf[i] == '\0') 343 continue; 344 textdump_block_buffer[offset] = buf[i]; 345 offset++; 346 if (offset != sizeof(textdump_block_buffer)) 347 continue; 348 (void)textdump_writenextblock(di, 349 textdump_block_buffer); 350 total_len += offset; 351 offset = 0; 352 } 353 } 354 total_len += offset; /* Without the zero-padding. */ 355 if (offset != 0) { 356 bzero(textdump_block_buffer + offset, 357 sizeof(textdump_block_buffer) - offset); 358 (void)textdump_writenextblock(di, textdump_block_buffer); 359 } 360 361 /* 362 * Rewrite tar header to reflect how much was actually written. 363 */ 364 textdump_saveoff(&end_offset); 365 textdump_restoreoff(tarhdr_offset); 366 textdump_mkustar(textdump_block_buffer, TAR_MSGBUF_FILENAME, 367 total_len); 368 (void)textdump_writenextblock(di, textdump_block_buffer); 369 textdump_restoreoff(end_offset); 370 } 371 372 static void 373 textdump_dump_panic(struct dumperinfo *di) 374 { 375 u_int len; 376 377 /* 378 * Write out tar header -- we store up to one block of panic message. 379 */ 380 len = min(strlen(panicstr), TEXTDUMP_BLOCKSIZE); 381 textdump_mkustar(textdump_block_buffer, TAR_PANIC_FILENAME, len); 382 (void)textdump_writenextblock(di, textdump_block_buffer); 383 384 /* 385 * Zero-pad the panic string and write out block. 386 */ 387 bzero(textdump_block_buffer, sizeof(textdump_block_buffer)); 388 bcopy(panicstr, textdump_block_buffer, len); 389 (void)textdump_writenextblock(di, textdump_block_buffer); 390 } 391 392 static void 393 textdump_dump_version(struct dumperinfo *di) 394 { 395 u_int len; 396 397 /* 398 * Write out tar header -- at most one block of version information. 399 */ 400 len = min(strlen(version), TEXTDUMP_BLOCKSIZE); 401 textdump_mkustar(textdump_block_buffer, TAR_VERSION_FILENAME, len); 402 (void)textdump_writenextblock(di, textdump_block_buffer); 403 404 /* 405 * Zero pad the version string and write out block. 406 */ 407 bzero(textdump_block_buffer, sizeof(textdump_block_buffer)); 408 bcopy(version, textdump_block_buffer, len); 409 (void)textdump_writenextblock(di, textdump_block_buffer); 410 } 411 412 /* 413 * Commit text dump to disk. 414 */ 415 void 416 textdump_dumpsys(struct dumperinfo *di) 417 { 418 off_t dumplen, trailer_offset; 419 420 if (di->blocksize != TEXTDUMP_BLOCKSIZE) { 421 printf("Dump partition block size (%ju) not textdump " 422 "block size (%ju)", (uintmax_t)di->blocksize, 423 (uintmax_t)TEXTDUMP_BLOCKSIZE); 424 return; 425 } 426 427 /* 428 * We don't know a priori how large the dump will be, but we do know 429 * that we need to reserve space for metadata and that we need two 430 * dump headers. Also leave room for one ustar header and one block 431 * of data. 432 */ 433 if (di->mediasize < SIZEOF_METADATA + 2 * sizeof(kdh)) { 434 printf("Insufficient space on dump partition.\n"); 435 return; 436 } 437 textdump_error = 0; 438 439 /* 440 * Position the start of the dump so that we'll write the kernel dump 441 * trailer immediately before the end of the partition, and then work 442 * our way back. We will rewrite this header later to reflect the 443 * true size if things go well. 444 */ 445 textdump_offset = di->mediasize - sizeof(kdh); 446 textdump_saveoff(&trailer_offset); 447 mkdumpheader(&kdh, TEXTDUMPMAGIC, KERNELDUMP_TEXT_VERSION, 0, TEXTDUMP_BLOCKSIZE); 448 (void)textdump_writenextblock(di, (char *)&kdh); 449 450 /* 451 * Write a series of files in ustar format. 452 */ 453 if (textdump_do_ddb) 454 db_capture_dump(di); 455 #ifdef INCLUDE_CONFIG_FILE 456 if (textdump_do_config) 457 textdump_dump_config(di); 458 #endif 459 if (textdump_do_msgbuf) 460 textdump_dump_msgbuf(di); 461 if (textdump_do_panic && panicstr != NULL) 462 textdump_dump_panic(di); 463 if (textdump_do_version) 464 textdump_dump_version(di); 465 466 /* 467 * Now that we know the true size, we can write out the header, then 468 * seek back to the end and rewrite the trailer with the correct 469 * size. 470 */ 471 dumplen = trailer_offset - (textdump_offset + TEXTDUMP_BLOCKSIZE); 472 mkdumpheader(&kdh, TEXTDUMPMAGIC, KERNELDUMP_TEXT_VERSION, dumplen, 473 TEXTDUMP_BLOCKSIZE); 474 (void)textdump_writenextblock(di, (char *)&kdh); 475 textdump_restoreoff(trailer_offset); 476 (void)textdump_writenextblock(di, (char *)&kdh); 477 478 /* 479 * Terminate the dump, report any errors, and clear the pending flag. 480 */ 481 if (textdump_error == 0) 482 (void)dump_write(di, NULL, 0, 0, 0); 483 if (textdump_error == ENOSPC) 484 printf("Insufficient space on dump partition\n"); 485 else if (textdump_error != 0) 486 printf("Error %d writing dump\n", textdump_error); 487 else 488 printf("Textdump complete.\n"); 489 textdump_pending = 0; 490 } 491 492 /*- 493 * DDB(4) command to manage textdumps: 494 * 495 * textdump set - request a textdump 496 * textdump status - print DDB output textdump status 497 * textdump unset - clear textdump request 498 */ 499 static void 500 db_textdump_usage(void) 501 { 502 503 db_printf("textdump [unset|set|status]\n"); 504 } 505 506 void 507 db_textdump_cmd(db_expr_t addr, boolean_t have_addr, db_expr_t count, 508 char *modif) 509 { 510 int t; 511 512 t = db_read_token(); 513 if (t != tIDENT) { 514 db_textdump_usage(); 515 return; 516 } 517 if (db_read_token() != tEOL) { 518 db_textdump_usage(); 519 return; 520 } 521 if (strcmp(db_tok_string, "set") == 0) { 522 textdump_pending = 1; 523 db_printf("textdump set\n"); 524 } else if (strcmp(db_tok_string, "status") == 0) { 525 if (textdump_pending) 526 db_printf("textdump is set\n"); 527 else 528 db_printf("textdump is not set\n"); 529 } else if (strcmp(db_tok_string, "unset") == 0) { 530 textdump_pending = 0; 531 db_printf("textdump unset\n"); 532 } else 533 db_textdump_usage(); 534 } 535