Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/geom/geom_bsd.c
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1 /*- 2 * Copyright (c) 2002 Poul-Henning Kamp 3 * Copyright (c) 2002 Networks Associates Technology, Inc. 4 * All rights reserved. 5 * 6 * This software was developed for the FreeBSD Project by Poul-Henning Kamp 7 * and NAI Labs, the Security Research Division of Network Associates, Inc. 8 * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the 9 * DARPA CHATS research program. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. The names of the authors may not be used to endorse or promote 20 * products derived from this software without specific prior written 21 * permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36 /* 37 * This is the method for dealing with BSD disklabels. It has been 38 * extensively (by my standards at least) commented, in the vain hope that 39 * it will serve as the source in future copy&paste operations. 40 */ 41 42 #include <sys/cdefs.h> 43 __FBSDID("$FreeBSD: releng/10.4/sys/geom/geom_bsd.c 322860 2017-08-24 21:44:23Z mckusick $"); 44 45 #include <sys/param.h> 46 #include <sys/endian.h> 47 #include <sys/systm.h> 48 #include <sys/sysctl.h> 49 #include <sys/kernel.h> 50 #include <sys/fcntl.h> 51 #include <sys/conf.h> 52 #include <sys/bio.h> 53 #include <sys/malloc.h> 54 #include <sys/lock.h> 55 #include <sys/mutex.h> 56 #include <sys/md5.h> 57 #include <sys/errno.h> 58 #include <sys/disklabel.h> 59 #include <sys/gpt.h> 60 #include <sys/proc.h> 61 #include <sys/sbuf.h> 62 #include <sys/uuid.h> 63 #include <geom/geom.h> 64 #include <geom/geom_slice.h> 65 66 FEATURE(geom_bsd, "GEOM BSD disklabels support"); 67 68 #define BSD_CLASS_NAME "BSD" 69 70 #define ALPHA_LABEL_OFFSET 64 71 #define HISTORIC_LABEL_OFFSET 512 72 73 #define LABELSIZE (148 + 16 * MAXPARTITIONS) 74 75 static void g_bsd_hotwrite(void *arg, int flag); 76 /* 77 * Our private data about one instance. All the rest is handled by the 78 * slice code and stored in its softc, so this is just the stuff 79 * specific to BSD disklabels. 80 */ 81 struct g_bsd_softc { 82 off_t labeloffset; 83 off_t mbroffset; 84 off_t rawoffset; 85 struct disklabel ondisk; 86 u_char label[LABELSIZE]; 87 u_char labelsum[16]; 88 }; 89 90 /* 91 * Modify our slicer to match proposed disklabel, if possible. 92 * This is where we make sure we don't do something stupid. 93 */ 94 static int 95 g_bsd_modify(struct g_geom *gp, u_char *label) 96 { 97 int i, error; 98 struct partition *ppp; 99 struct g_slicer *gsp; 100 struct g_consumer *cp; 101 struct g_bsd_softc *ms; 102 u_int secsize, u; 103 off_t rawoffset, o; 104 struct disklabel dl; 105 MD5_CTX md5sum; 106 107 g_topology_assert(); 108 gsp = gp->softc; 109 ms = gsp->softc; 110 111 error = bsd_disklabel_le_dec(label, &dl, MAXPARTITIONS); 112 if (error) { 113 return (error); 114 } 115 116 /* Get dimensions of our device. */ 117 cp = LIST_FIRST(&gp->consumer); 118 secsize = cp->provider->sectorsize; 119 120 /* ... or a smaller sector size. */ 121 if (dl.d_secsize < secsize) { 122 return (EINVAL); 123 } 124 125 /* ... or a non-multiple sector size. */ 126 if (dl.d_secsize % secsize != 0) { 127 return (EINVAL); 128 } 129 130 /* Historical braindamage... */ 131 rawoffset = (off_t)dl.d_partitions[RAW_PART].p_offset * dl.d_secsize; 132 133 for (i = 0; i < dl.d_npartitions; i++) { 134 ppp = &dl.d_partitions[i]; 135 if (ppp->p_size == 0) 136 continue; 137 o = (off_t)ppp->p_offset * dl.d_secsize; 138 139 if (o < rawoffset) 140 rawoffset = 0; 141 } 142 143 if (rawoffset != 0 && (off_t)rawoffset != ms->mbroffset) 144 printf("WARNING: %s expected rawoffset %jd, found %jd\n", 145 gp->name, 146 (intmax_t)ms->mbroffset/dl.d_secsize, 147 (intmax_t)rawoffset/dl.d_secsize); 148 149 /* Don't munge open partitions. */ 150 for (i = 0; i < dl.d_npartitions; i++) { 151 ppp = &dl.d_partitions[i]; 152 153 o = (off_t)ppp->p_offset * dl.d_secsize; 154 if (o == 0) 155 o = rawoffset; 156 error = g_slice_config(gp, i, G_SLICE_CONFIG_CHECK, 157 o - rawoffset, 158 (off_t)ppp->p_size * dl.d_secsize, 159 dl.d_secsize, 160 "%s%c", gp->name, 'a' + i); 161 if (error) 162 return (error); 163 } 164 165 /* Look good, go for it... */ 166 for (u = 0; u < gsp->nslice; u++) { 167 ppp = &dl.d_partitions[u]; 168 o = (off_t)ppp->p_offset * dl.d_secsize; 169 if (o == 0) 170 o = rawoffset; 171 g_slice_config(gp, u, G_SLICE_CONFIG_SET, 172 o - rawoffset, 173 (off_t)ppp->p_size * dl.d_secsize, 174 dl.d_secsize, 175 "%s%c", gp->name, 'a' + u); 176 } 177 178 /* Update our softc */ 179 ms->ondisk = dl; 180 if (label != ms->label) 181 bcopy(label, ms->label, LABELSIZE); 182 ms->rawoffset = rawoffset; 183 184 /* 185 * In order to avoid recursively attaching to the same 186 * on-disk label (it's usually visible through the 'c' 187 * partition) we calculate an MD5 and ask if other BSD's 188 * below us love that label. If they do, we don't. 189 */ 190 MD5Init(&md5sum); 191 MD5Update(&md5sum, ms->label, sizeof(ms->label)); 192 MD5Final(ms->labelsum, &md5sum); 193 194 return (0); 195 } 196 197 /* 198 * This is an internal helper function, called multiple times from the taste 199 * function to try to locate a disklabel on the disk. More civilized formats 200 * will not need this, as there is only one possible place on disk to look 201 * for the magic spot. 202 */ 203 204 static int 205 g_bsd_try(struct g_geom *gp, struct g_slicer *gsp, struct g_consumer *cp, int secsize, struct g_bsd_softc *ms, off_t offset) 206 { 207 int error; 208 u_char *buf; 209 struct disklabel *dl; 210 off_t secoff; 211 212 /* 213 * We need to read entire aligned sectors, and we assume that the 214 * disklabel does not span sectors, so one sector is enough. 215 */ 216 secoff = offset % secsize; 217 buf = g_read_data(cp, offset - secoff, secsize, NULL); 218 if (buf == NULL) 219 return (ENOENT); 220 221 /* Decode into our native format. */ 222 dl = &ms->ondisk; 223 error = bsd_disklabel_le_dec(buf + secoff, dl, MAXPARTITIONS); 224 if (!error) 225 bcopy(buf + secoff, ms->label, LABELSIZE); 226 227 /* Remember to free the buffer g_read_data() gave us. */ 228 g_free(buf); 229 230 ms->labeloffset = offset; 231 return (error); 232 } 233 234 /* 235 * This function writes the current label to disk, possibly updating 236 * the alpha SRM checksum. 237 */ 238 239 static int 240 g_bsd_writelabel(struct g_geom *gp, u_char *bootcode) 241 { 242 off_t secoff; 243 u_int secsize; 244 struct g_consumer *cp; 245 struct g_slicer *gsp; 246 struct g_bsd_softc *ms; 247 u_char *buf; 248 uint64_t sum; 249 int error, i; 250 251 gsp = gp->softc; 252 ms = gsp->softc; 253 cp = LIST_FIRST(&gp->consumer); 254 /* Get sector size, we need it to read data. */ 255 secsize = cp->provider->sectorsize; 256 secoff = ms->labeloffset % secsize; 257 if (bootcode == NULL) { 258 buf = g_read_data(cp, ms->labeloffset - secoff, secsize, &error); 259 if (buf == NULL) 260 return (error); 261 bcopy(ms->label, buf + secoff, sizeof(ms->label)); 262 } else { 263 buf = bootcode; 264 bcopy(ms->label, buf + ms->labeloffset, sizeof(ms->label)); 265 } 266 if (ms->labeloffset == ALPHA_LABEL_OFFSET) { 267 sum = 0; 268 for (i = 0; i < 63; i++) 269 sum += le64dec(buf + i * 8); 270 le64enc(buf + 504, sum); 271 } 272 if (bootcode == NULL) { 273 error = g_write_data(cp, ms->labeloffset - secoff, buf, secsize); 274 g_free(buf); 275 } else { 276 error = g_write_data(cp, 0, bootcode, BBSIZE); 277 } 278 return(error); 279 } 280 281 /* 282 * If the user tries to overwrite our disklabel through an open partition 283 * or via a magicwrite config call, we end up here and try to prevent 284 * footshooting as best we can. 285 */ 286 static void 287 g_bsd_hotwrite(void *arg, int flag) 288 { 289 struct bio *bp; 290 struct g_geom *gp; 291 struct g_slicer *gsp; 292 struct g_slice *gsl; 293 struct g_bsd_softc *ms; 294 u_char *p; 295 int error; 296 297 g_topology_assert(); 298 /* 299 * We should never get canceled, because that would amount to a removal 300 * of the geom while there was outstanding I/O requests. 301 */ 302 KASSERT(flag != EV_CANCEL, ("g_bsd_hotwrite cancelled")); 303 bp = arg; 304 gp = bp->bio_to->geom; 305 gsp = gp->softc; 306 ms = gsp->softc; 307 gsl = &gsp->slices[bp->bio_to->index]; 308 p = (u_char*)bp->bio_data + ms->labeloffset - 309 (bp->bio_offset + gsl->offset); 310 error = g_bsd_modify(gp, p); 311 if (error) { 312 g_io_deliver(bp, EPERM); 313 return; 314 } 315 g_slice_finish_hot(bp); 316 } 317 318 static int 319 g_bsd_start(struct bio *bp) 320 { 321 struct g_geom *gp; 322 struct g_bsd_softc *ms; 323 struct g_slicer *gsp; 324 325 gp = bp->bio_to->geom; 326 gsp = gp->softc; 327 ms = gsp->softc; 328 if (bp->bio_cmd == BIO_GETATTR) { 329 if (g_handleattr(bp, "BSD::labelsum", ms->labelsum, 330 sizeof(ms->labelsum))) 331 return (1); 332 } 333 return (0); 334 } 335 336 /* 337 * Dump configuration information in XML format. 338 * Notice that the function is called once for the geom and once for each 339 * consumer and provider. We let g_slice_dumpconf() do most of the work. 340 */ 341 static void 342 g_bsd_dumpconf(struct sbuf *sb, const char *indent, struct g_geom *gp, struct g_consumer *cp, struct g_provider *pp) 343 { 344 struct g_bsd_softc *ms; 345 struct g_slicer *gsp; 346 347 gsp = gp->softc; 348 ms = gsp->softc; 349 g_slice_dumpconf(sb, indent, gp, cp, pp); 350 if (indent != NULL && pp == NULL && cp == NULL) { 351 sbuf_printf(sb, "%s<labeloffset>%jd</labeloffset>\n", 352 indent, (intmax_t)ms->labeloffset); 353 sbuf_printf(sb, "%s<rawoffset>%jd</rawoffset>\n", 354 indent, (intmax_t)ms->rawoffset); 355 sbuf_printf(sb, "%s<mbroffset>%jd</mbroffset>\n", 356 indent, (intmax_t)ms->mbroffset); 357 } else if (pp != NULL) { 358 if (indent == NULL) 359 sbuf_printf(sb, " ty %d", 360 ms->ondisk.d_partitions[pp->index].p_fstype); 361 else 362 sbuf_printf(sb, "%s<type>%d</type>\n", indent, 363 ms->ondisk.d_partitions[pp->index].p_fstype); 364 } 365 } 366 367 /* 368 * The taste function is called from the event-handler, with the topology 369 * lock already held and a provider to examine. The flags are unused. 370 * 371 * If flags == G_TF_NORMAL, the idea is to take a bite of the provider and 372 * if we find valid, consistent magic on it, build a geom on it. 373 * 374 * There may be cases where the operator would like to put a BSD-geom on 375 * providers which do not meet all of the requirements. This can be done 376 * by instead passing the G_TF_INSIST flag, which will override these 377 * checks. 378 * 379 * The final flags value is G_TF_TRANSPARENT, which instructs the method 380 * to put a geom on top of the provider and configure it to be as transparent 381 * as possible. This is not really relevant to the BSD method and therefore 382 * not implemented here. 383 */ 384 385 static struct uuid freebsd_slice = GPT_ENT_TYPE_FREEBSD; 386 387 static struct g_geom * 388 g_bsd_taste(struct g_class *mp, struct g_provider *pp, int flags) 389 { 390 struct g_geom *gp; 391 struct g_consumer *cp; 392 int error, i; 393 struct g_bsd_softc *ms; 394 u_int secsize; 395 struct g_slicer *gsp; 396 u_char hash[16]; 397 MD5_CTX md5sum; 398 struct uuid uuid; 399 400 g_trace(G_T_TOPOLOGY, "bsd_taste(%s,%s)", mp->name, pp->name); 401 g_topology_assert(); 402 403 /* We don't implement transparent inserts. */ 404 if (flags == G_TF_TRANSPARENT) 405 return (NULL); 406 407 /* 408 * BSD labels are a subclass of the general "slicing" topology so 409 * a lot of the work can be done by the common "slice" code. 410 * Create a geom with space for MAXPARTITIONS providers, one consumer 411 * and a softc structure for us. Specify the provider to attach 412 * the consumer to and our "start" routine for special requests. 413 * The provider is opened with mode (1,0,0) so we can do reads 414 * from it. 415 */ 416 gp = g_slice_new(mp, MAXPARTITIONS, pp, &cp, &ms, 417 sizeof(*ms), g_bsd_start); 418 if (gp == NULL) 419 return (NULL); 420 421 /* Get the geom_slicer softc from the geom. */ 422 gsp = gp->softc; 423 424 /* 425 * The do...while loop here allows us to have multiple escapes 426 * using a simple "break". This improves code clarity without 427 * ending up in deep nesting and without using goto or come from. 428 */ 429 do { 430 /* 431 * If the provider is an MBR we will only auto attach 432 * to type 165 slices in the G_TF_NORMAL case. We will 433 * attach to any other type. 434 */ 435 error = g_getattr("MBR::type", cp, &i); 436 if (!error) { 437 if (i != 165 && flags == G_TF_NORMAL) 438 break; 439 error = g_getattr("MBR::offset", cp, &ms->mbroffset); 440 if (error) 441 break; 442 } 443 444 /* Same thing if we are inside a PC98 */ 445 error = g_getattr("PC98::type", cp, &i); 446 if (!error) { 447 if (i != 0xc494 && flags == G_TF_NORMAL) 448 break; 449 error = g_getattr("PC98::offset", cp, &ms->mbroffset); 450 if (error) 451 break; 452 } 453 454 /* Same thing if we are inside a GPT */ 455 error = g_getattr("GPT::type", cp, &uuid); 456 if (!error) { 457 if (memcmp(&uuid, &freebsd_slice, sizeof(uuid)) != 0 && 458 flags == G_TF_NORMAL) 459 break; 460 } 461 462 /* Get sector size, we need it to read data. */ 463 secsize = cp->provider->sectorsize; 464 if (secsize < 512) 465 break; 466 467 /* First look for a label at the start of the second sector. */ 468 error = g_bsd_try(gp, gsp, cp, secsize, ms, secsize); 469 470 /* 471 * If sector size is not 512 the label still can be at 472 * offset 512, not at the start of the second sector. At least 473 * it's true for labels created by the FreeBSD's bsdlabel(8). 474 */ 475 if (error && secsize != HISTORIC_LABEL_OFFSET) 476 error = g_bsd_try(gp, gsp, cp, secsize, ms, 477 HISTORIC_LABEL_OFFSET); 478 479 /* Next, look for alpha labels */ 480 if (error) 481 error = g_bsd_try(gp, gsp, cp, secsize, ms, 482 ALPHA_LABEL_OFFSET); 483 484 /* If we didn't find a label, punt. */ 485 if (error) 486 break; 487 488 /* 489 * In order to avoid recursively attaching to the same 490 * on-disk label (it's usually visible through the 'c' 491 * partition) we calculate an MD5 and ask if other BSD's 492 * below us love that label. If they do, we don't. 493 */ 494 MD5Init(&md5sum); 495 MD5Update(&md5sum, ms->label, sizeof(ms->label)); 496 MD5Final(ms->labelsum, &md5sum); 497 498 error = g_getattr("BSD::labelsum", cp, &hash); 499 if (!error && !bcmp(ms->labelsum, hash, sizeof(hash))) 500 break; 501 502 /* 503 * Process the found disklabel, and modify our "slice" 504 * instance to match it, if possible. 505 */ 506 error = g_bsd_modify(gp, ms->label); 507 } while (0); 508 509 /* Success or failure, we can close our provider now. */ 510 g_access(cp, -1, 0, 0); 511 512 /* If we have configured any providers, return the new geom. */ 513 if (gsp->nprovider > 0) { 514 g_slice_conf_hot(gp, 0, ms->labeloffset, LABELSIZE, 515 G_SLICE_HOT_ALLOW, G_SLICE_HOT_DENY, G_SLICE_HOT_CALL); 516 gsp->hot = g_bsd_hotwrite; 517 return (gp); 518 } 519 /* 520 * ...else push the "self-destruct" button, by spoiling our own 521 * consumer. This triggers a call to g_slice_spoiled which will 522 * dismantle what was setup. 523 */ 524 g_slice_spoiled(cp); 525 return (NULL); 526 } 527 528 struct h0h0 { 529 struct g_geom *gp; 530 struct g_bsd_softc *ms; 531 u_char *label; 532 int error; 533 }; 534 535 static void 536 g_bsd_callconfig(void *arg, int flag) 537 { 538 struct h0h0 *hp; 539 540 hp = arg; 541 hp->error = g_bsd_modify(hp->gp, hp->label); 542 if (!hp->error) 543 hp->error = g_bsd_writelabel(hp->gp, NULL); 544 } 545 546 /* 547 * NB! curthread is user process which GCTL'ed. 548 */ 549 static void 550 g_bsd_config(struct gctl_req *req, struct g_class *mp, char const *verb) 551 { 552 u_char *label; 553 int error; 554 struct h0h0 h0h0; 555 struct g_geom *gp; 556 struct g_slicer *gsp; 557 struct g_consumer *cp; 558 struct g_bsd_softc *ms; 559 560 g_topology_assert(); 561 gp = gctl_get_geom(req, mp, "geom"); 562 if (gp == NULL) 563 return; 564 cp = LIST_FIRST(&gp->consumer); 565 gsp = gp->softc; 566 ms = gsp->softc; 567 if (!strcmp(verb, "read mbroffset")) { 568 gctl_set_param_err(req, "mbroffset", &ms->mbroffset, 569 sizeof(ms->mbroffset)); 570 return; 571 } else if (!strcmp(verb, "write label")) { 572 label = gctl_get_paraml(req, "label", LABELSIZE); 573 if (label == NULL) 574 return; 575 h0h0.gp = gp; 576 h0h0.ms = gsp->softc; 577 h0h0.label = label; 578 h0h0.error = -1; 579 /* XXX: Does this reference register with our selfdestruct code ? */ 580 error = g_access(cp, 1, 1, 1); 581 if (error) { 582 gctl_error(req, "could not access consumer"); 583 return; 584 } 585 g_bsd_callconfig(&h0h0, 0); 586 error = h0h0.error; 587 g_access(cp, -1, -1, -1); 588 } else if (!strcmp(verb, "write bootcode")) { 589 label = gctl_get_paraml(req, "bootcode", BBSIZE); 590 if (label == NULL) 591 return; 592 /* XXX: Does this reference register with our selfdestruct code ? */ 593 error = g_access(cp, 1, 1, 1); 594 if (error) { 595 gctl_error(req, "could not access consumer"); 596 return; 597 } 598 error = g_bsd_writelabel(gp, label); 599 g_access(cp, -1, -1, -1); 600 } else { 601 gctl_error(req, "Unknown verb parameter"); 602 } 603 604 return; 605 } 606 607 /* Finally, register with GEOM infrastructure. */ 608 static struct g_class g_bsd_class = { 609 .name = BSD_CLASS_NAME, 610 .version = G_VERSION, 611 .taste = g_bsd_taste, 612 .ctlreq = g_bsd_config, 613 .dumpconf = g_bsd_dumpconf, 614 }; 615 616 DECLARE_GEOM_CLASS(g_bsd_class, g_bsd);
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