The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/geom/geom_mbr.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  *
   20  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   30  * SUCH DAMAGE.
   31  */
   32 
   33 #include <sys/cdefs.h>
   34 __FBSDID("$FreeBSD: releng/11.1/sys/geom/geom_mbr.c 300288 2016-05-20 08:25:37Z kib $");
   35 
   36 #include <sys/param.h>
   37 #include <sys/errno.h>
   38 #include <sys/endian.h>
   39 #include <sys/systm.h>
   40 #include <sys/sysctl.h>
   41 #include <sys/kernel.h>
   42 #include <sys/fcntl.h>
   43 #include <sys/malloc.h>
   44 #include <sys/bio.h>
   45 #include <sys/lock.h>
   46 #include <sys/mutex.h>
   47 #include <sys/md5.h>
   48 #include <sys/proc.h>
   49 
   50 #include <sys/diskmbr.h>
   51 #include <sys/sbuf.h>
   52 #include <geom/geom.h>
   53 #include <geom/geom_slice.h>
   54 
   55 FEATURE(geom_mbr, "GEOM DOS/MBR partitioning support");
   56 
   57 #define MBR_CLASS_NAME "MBR"
   58 #define MBREXT_CLASS_NAME "MBREXT"
   59 
   60 static struct dos_partition historical_bogus_partition_table[NDOSPART] = {
   61         { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
   62         { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
   63         { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
   64         { 0x80, 0, 1, 0, DOSPTYP_386BSD, 255, 255, 255, 0, 50000, },
   65 };
   66 
   67 static struct dos_partition historical_bogus_partition_table_fixed[NDOSPART] = {
   68         { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
   69         { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
   70         { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
   71         { 0x80, 0, 1, 0, DOSPTYP_386BSD, 254, 255, 255, 0, 50000, },
   72 };
   73 
   74 static void
   75 g_mbr_print(int i, struct dos_partition *dp)
   76 {
   77 
   78         printf("[%d] f:%02x typ:%d", i, dp->dp_flag, dp->dp_typ);
   79         printf(" s(CHS):%d/%d/%d", DPCYL(dp->dp_scyl, dp->dp_ssect),
   80             dp->dp_shd, DPSECT(dp->dp_ssect));
   81         printf(" e(CHS):%d/%d/%d", DPCYL(dp->dp_ecyl, dp->dp_esect),
   82             dp->dp_ehd, DPSECT(dp->dp_esect));
   83         printf(" s:%d l:%d\n", dp->dp_start, dp->dp_size);
   84 }
   85 
   86 struct g_mbr_softc {
   87         int             type [NDOSPART];
   88         u_int           sectorsize;
   89         u_char          sec0[512];
   90         u_char          slicesum[16];
   91 };
   92 
   93 /*
   94  * XXX: Add gctl_req arg and give good error msgs.
   95  * XXX: Check that length argument does not bring boot code inside any slice.
   96  */
   97 static int
   98 g_mbr_modify(struct g_geom *gp, struct g_mbr_softc *ms, u_char *sec0, int len __unused)
   99 {
  100         int i, error;
  101         off_t l[NDOSPART];
  102         struct dos_partition ndp[NDOSPART], *dp;
  103         MD5_CTX md5sum;
  104 
  105         g_topology_assert();
  106 
  107         if (sec0[0x1fe] != 0x55 && sec0[0x1ff] != 0xaa)
  108                 return (EBUSY);
  109 
  110         dp = ndp;
  111         for (i = 0; i < NDOSPART; i++) {
  112                 dos_partition_dec(
  113                     sec0 + DOSPARTOFF + i * sizeof(struct dos_partition),
  114                     dp + i);
  115         }
  116         if ((!bcmp(dp, historical_bogus_partition_table,
  117             sizeof historical_bogus_partition_table)) ||
  118             (!bcmp(dp, historical_bogus_partition_table_fixed,
  119             sizeof historical_bogus_partition_table_fixed))) {
  120                 /*
  121                  * We will not allow people to write these from "the inside",
  122                  * Since properly selfdestructing takes too much code.  If 
  123                  * people really want to do this, they cannot have any
  124                  * providers of this geom open, and in that case they can just
  125                  * as easily overwrite the MBR in the parent device.
  126                  */
  127                 return(EBUSY);
  128         }
  129         for (i = 0; i < NDOSPART; i++) {
  130                 /* 
  131                  * A Protective MBR (PMBR) has a single partition of
  132                  * type 0xEE spanning the whole disk. Such a MBR
  133                  * protects a GPT on the disk from MBR tools that
  134                  * don't know anything about GPT. We're interpreting
  135                  * it a bit more loosely: any partition of type 0xEE
  136                  * is to be skipped as it doesn't contain any data
  137                  * that we should care about. We still allow other
  138                  * partitions to be present in the MBR. A PMBR will
  139                  * be handled correctly anyway.
  140                  */
  141                 if (dp[i].dp_typ == DOSPTYP_PMBR)
  142                         l[i] = 0;
  143                 else if (dp[i].dp_flag != 0 && dp[i].dp_flag != 0x80)
  144                         l[i] = 0;
  145                 else if (dp[i].dp_typ == 0)
  146                         l[i] = 0;
  147                 else
  148                         l[i] = (off_t)dp[i].dp_size * ms->sectorsize;
  149                 error = g_slice_config(gp, i, G_SLICE_CONFIG_CHECK,
  150                     (off_t)dp[i].dp_start * ms->sectorsize, l[i],
  151                     ms->sectorsize, "%ss%d", gp->name, 1 + i);
  152                 if (error)
  153                         return (error);
  154         }
  155         for (i = 0; i < NDOSPART; i++) {
  156                 ms->type[i] = dp[i].dp_typ;
  157                 g_slice_config(gp, i, G_SLICE_CONFIG_SET,
  158                     (off_t)dp[i].dp_start * ms->sectorsize, l[i],
  159                     ms->sectorsize, "%ss%d", gp->name, 1 + i);
  160         }
  161         bcopy(sec0, ms->sec0, 512);
  162 
  163         /*
  164          * Calculate MD5 from the first sector and use it for avoiding
  165          * recursive slices creation.
  166          */
  167         MD5Init(&md5sum);
  168         MD5Update(&md5sum, ms->sec0, sizeof(ms->sec0));
  169         MD5Final(ms->slicesum, &md5sum);
  170 
  171         return (0);
  172 }
  173 
  174 static int
  175 g_mbr_ioctl(struct g_provider *pp, u_long cmd, void *data, int fflag, struct thread *td)
  176 {
  177         struct g_geom *gp;
  178         struct g_mbr_softc *ms;
  179         struct g_slicer *gsp;
  180         struct g_consumer *cp;
  181         int error, opened;
  182 
  183         gp = pp->geom;
  184         gsp = gp->softc;
  185         ms = gsp->softc;
  186 
  187         opened = 0;
  188         error = 0;
  189         switch(cmd) {
  190         case DIOCSMBR: {
  191                 if (!(fflag & FWRITE))
  192                         return (EPERM);
  193                 g_topology_lock();
  194                 cp = LIST_FIRST(&gp->consumer);
  195                 if (cp->acw == 0) {
  196                         error = g_access(cp, 0, 1, 0);
  197                         if (error == 0)
  198                                 opened = 1;
  199                 }
  200                 if (!error)
  201                         error = g_mbr_modify(gp, ms, data, 512);
  202                 if (!error)
  203                         error = g_write_data(cp, 0, data, 512);
  204                 if (opened)
  205                         g_access(cp, 0, -1 , 0);
  206                 g_topology_unlock();
  207                 return(error);
  208         }
  209         default:
  210                 return (ENOIOCTL);
  211         }
  212 }
  213 
  214 static int
  215 g_mbr_start(struct bio *bp)
  216 {
  217         struct g_provider *pp;
  218         struct g_geom *gp;
  219         struct g_mbr_softc *mp;
  220         struct g_slicer *gsp;
  221         int idx;
  222 
  223         pp = bp->bio_to;
  224         idx = pp->index;
  225         gp = pp->geom;
  226         gsp = gp->softc;
  227         mp = gsp->softc;
  228         if (bp->bio_cmd == BIO_GETATTR) {
  229                 if (g_handleattr_int(bp, "MBR::type", mp->type[idx]))
  230                         return (1);
  231                 if (g_handleattr_off_t(bp, "MBR::offset",
  232                     gsp->slices[idx].offset))
  233                         return (1);
  234                 if (g_handleattr(bp, "MBR::slicesum", mp->slicesum,
  235                     sizeof(mp->slicesum)))
  236                         return (1);
  237         }
  238 
  239         return (0);
  240 }
  241 
  242 static void
  243 g_mbr_dumpconf(struct sbuf *sb, const char *indent, struct g_geom *gp, struct g_consumer *cp __unused, struct g_provider *pp)
  244 {
  245         struct g_mbr_softc *mp;
  246         struct g_slicer *gsp;
  247 
  248         gsp = gp->softc;
  249         mp = gsp->softc;
  250         g_slice_dumpconf(sb, indent, gp, cp, pp);
  251         if (pp != NULL) {
  252                 if (indent == NULL)
  253                         sbuf_printf(sb, " ty %d", mp->type[pp->index]);
  254                 else
  255                         sbuf_printf(sb, "%s<type>%d</type>\n", indent,
  256                             mp->type[pp->index]);
  257         }
  258 }
  259 
  260 static struct g_geom *
  261 g_mbr_taste(struct g_class *mp, struct g_provider *pp, int insist)
  262 {
  263         struct g_geom *gp;
  264         struct g_consumer *cp;
  265         int error;
  266         struct g_mbr_softc *ms;
  267         u_int fwsectors, sectorsize;
  268         u_char *buf;
  269         u_char hash[16];
  270         MD5_CTX md5sum;
  271 
  272         g_trace(G_T_TOPOLOGY, "mbr_taste(%s,%s)", mp->name, pp->name);
  273         g_topology_assert();
  274         if (!strcmp(pp->geom->class->name, MBR_CLASS_NAME))
  275                 return (NULL);
  276         gp = g_slice_new(mp, NDOSPART, pp, &cp, &ms, sizeof *ms, g_mbr_start);
  277         if (gp == NULL)
  278                 return (NULL);
  279         g_topology_unlock();
  280         do {
  281                 error = g_getattr("GEOM::fwsectors", cp, &fwsectors);
  282                 if (error)
  283                         fwsectors = 17;
  284                 sectorsize = cp->provider->sectorsize;
  285                 if (sectorsize < 512)
  286                         break;
  287                 ms->sectorsize = sectorsize;
  288                 buf = g_read_data(cp, 0, sectorsize, NULL);
  289                 if (buf == NULL)
  290                         break;
  291 
  292                 /*
  293                  * Calculate MD5 from the first sector and use it for avoiding
  294                  * recursive slices creation.
  295                  */
  296                 bcopy(buf, ms->sec0, 512);
  297                 MD5Init(&md5sum);
  298                 MD5Update(&md5sum, ms->sec0, sizeof(ms->sec0));
  299                 MD5Final(ms->slicesum, &md5sum);
  300 
  301                 error = g_getattr("MBR::slicesum", cp, &hash);
  302                 if (!error && !bcmp(ms->slicesum, hash, sizeof(hash))) {
  303                         g_free(buf);
  304                         break;
  305                 }
  306 
  307                 g_topology_lock();
  308                 g_mbr_modify(gp, ms, buf, 512);
  309                 g_topology_unlock();
  310                 g_free(buf);
  311                 break;
  312         } while (0);
  313         g_topology_lock();
  314         g_access(cp, -1, 0, 0);
  315         if (LIST_EMPTY(&gp->provider)) {
  316                 g_slice_spoiled(cp);
  317                 return (NULL);
  318         }
  319         return (gp);
  320 }
  321 
  322 static void
  323 g_mbr_config(struct gctl_req *req, struct g_class *mp, const char *verb)
  324 {
  325         struct g_geom *gp;
  326         struct g_consumer *cp;
  327         struct g_mbr_softc *ms;
  328         struct g_slicer *gsp;
  329         int opened = 0, error = 0;
  330         void *data;
  331         int len;
  332 
  333         g_topology_assert();
  334         gp = gctl_get_geom(req, mp, "geom");
  335         if (gp == NULL)
  336                 return;
  337         if (strcmp(verb, "write MBR")) {
  338                 gctl_error(req, "Unknown verb");
  339                 return;
  340         }
  341         gsp = gp->softc;
  342         ms = gsp->softc;
  343         data = gctl_get_param(req, "data", &len);
  344         if (data == NULL)
  345                 return;
  346         if (len < 512 || (len % 512)) {
  347                 gctl_error(req, "Wrong request length");
  348                 return;
  349         }
  350         cp = LIST_FIRST(&gp->consumer);
  351         if (cp->acw == 0) {
  352                 error = g_access(cp, 0, 1, 0);
  353                 if (error == 0)
  354                         opened = 1;
  355         }
  356         if (!error)
  357                 error = g_mbr_modify(gp, ms, data, len);
  358         if (error)
  359                 gctl_error(req, "conflict with open slices");
  360         if (!error)
  361                 error = g_write_data(cp, 0, data, len);
  362         if (error)
  363                 gctl_error(req, "sector zero write failed");
  364         if (opened)
  365                 g_access(cp, 0, -1 , 0);
  366         return;
  367 }
  368 
  369 static struct g_class g_mbr_class       = {
  370         .name = MBR_CLASS_NAME,
  371         .version = G_VERSION,
  372         .taste = g_mbr_taste,
  373         .dumpconf = g_mbr_dumpconf,
  374         .ctlreq = g_mbr_config,
  375         .ioctl = g_mbr_ioctl,
  376 };
  377 
  378 DECLARE_GEOM_CLASS(g_mbr_class, g_mbr);
  379 
  380 #define NDOSEXTPART             32
  381 struct g_mbrext_softc {
  382         int             type [NDOSEXTPART];
  383 };
  384 
  385 static int
  386 g_mbrext_start(struct bio *bp)
  387 {
  388         struct g_provider *pp;
  389         struct g_geom *gp;
  390         struct g_mbrext_softc *mp;
  391         struct g_slicer *gsp;
  392         int idx;
  393 
  394         pp = bp->bio_to;
  395         idx = pp->index;
  396         gp = pp->geom;
  397         gsp = gp->softc;
  398         mp = gsp->softc;
  399         if (bp->bio_cmd == BIO_GETATTR) {
  400                 if (g_handleattr_int(bp, "MBR::type", mp->type[idx]))
  401                         return (1);
  402         }
  403         return (0);
  404 }
  405 
  406 static void
  407 g_mbrext_dumpconf(struct sbuf *sb, const char *indent, struct g_geom *gp, struct g_consumer *cp __unused, struct g_provider *pp)
  408 {
  409         struct g_mbrext_softc *mp;
  410         struct g_slicer *gsp;
  411 
  412         g_slice_dumpconf(sb, indent, gp, cp, pp);
  413         gsp = gp->softc;
  414         mp = gsp->softc;
  415         if (pp != NULL) {
  416                 if (indent == NULL)
  417                         sbuf_printf(sb, " ty %d", mp->type[pp->index]);
  418                 else
  419                         sbuf_printf(sb, "%s<type>%d</type>\n", indent,
  420                             mp->type[pp->index]);
  421         }
  422 }
  423 
  424 static struct g_geom *
  425 g_mbrext_taste(struct g_class *mp, struct g_provider *pp, int insist __unused)
  426 {
  427         struct g_geom *gp;
  428         struct g_consumer *cp;
  429         int error, i, slice;
  430         struct g_mbrext_softc *ms;
  431         off_t off;
  432         u_char *buf;
  433         struct dos_partition dp[4];
  434         u_int fwsectors, sectorsize;
  435 
  436         g_trace(G_T_TOPOLOGY, "g_mbrext_taste(%s,%s)", mp->name, pp->name);
  437         g_topology_assert();
  438         if (strcmp(pp->geom->class->name, MBR_CLASS_NAME))
  439                 return (NULL);
  440         gp = g_slice_new(mp, NDOSEXTPART, pp, &cp, &ms, sizeof *ms,
  441             g_mbrext_start);
  442         if (gp == NULL)
  443                 return (NULL);
  444         g_topology_unlock();
  445         off = 0;
  446         slice = 0;
  447         do {
  448                 error = g_getattr("MBR::type", cp, &i);
  449                 if (error || (i != DOSPTYP_EXT && i != DOSPTYP_EXTLBA))
  450                         break;
  451                 error = g_getattr("GEOM::fwsectors", cp, &fwsectors);
  452                 if (error)
  453                         fwsectors = 17;
  454                 sectorsize = cp->provider->sectorsize;
  455                 if (sectorsize != 512)
  456                         break;
  457                 for (;;) {
  458                         buf = g_read_data(cp, off, sectorsize, NULL);
  459                         if (buf == NULL)
  460                                 break;
  461                         if (buf[0x1fe] != 0x55 && buf[0x1ff] != 0xaa) {
  462                                 g_free(buf);
  463                                 break;
  464                         }
  465                         for (i = 0; i < NDOSPART; i++) 
  466                                 dos_partition_dec(
  467                                     buf + DOSPARTOFF + 
  468                                     i * sizeof(struct dos_partition), dp + i);
  469                         g_free(buf);
  470                         if (0 && bootverbose) {
  471                                 printf("MBREXT Slice %d on %s:\n",
  472                                     slice + 5, gp->name);
  473                                 g_mbr_print(0, dp);
  474                                 g_mbr_print(1, dp + 1);
  475                         }
  476                         if ((dp[0].dp_flag & 0x7f) == 0 &&
  477                              dp[0].dp_size != 0 && dp[0].dp_typ != 0) {
  478                                 g_topology_lock();
  479                                 g_slice_config(gp, slice, G_SLICE_CONFIG_SET,
  480                                     (((off_t)dp[0].dp_start) << 9ULL) + off,
  481                                     ((off_t)dp[0].dp_size) << 9ULL,
  482                                     sectorsize,
  483                                     "%*.*s%d",
  484                                     (int)strlen(gp->name) - 1,
  485                                     (int)strlen(gp->name) - 1,
  486                                     gp->name,
  487                                     slice + 5);
  488                                 g_topology_unlock();
  489                                 ms->type[slice] = dp[0].dp_typ;
  490                                 slice++;
  491                         }
  492                         if (dp[1].dp_flag != 0)
  493                                 break;
  494                         if (dp[1].dp_typ != DOSPTYP_EXT &&
  495                             dp[1].dp_typ != DOSPTYP_EXTLBA)
  496                                 break;
  497                         if (dp[1].dp_size == 0)
  498                                 break;
  499                         off = ((off_t)dp[1].dp_start) << 9ULL;
  500                 }
  501                 break;
  502         } while (0);
  503         g_topology_lock();
  504         g_access(cp, -1, 0, 0);
  505         if (LIST_EMPTY(&gp->provider)) {
  506                 g_slice_spoiled(cp);
  507                 return (NULL);
  508         }
  509         return (gp);
  510 }
  511 
  512 
  513 static struct g_class g_mbrext_class    = {
  514         .name = MBREXT_CLASS_NAME,
  515         .version = G_VERSION,
  516         .taste = g_mbrext_taste,
  517         .dumpconf = g_mbrext_dumpconf,
  518 };
  519 
  520 DECLARE_GEOM_CLASS(g_mbrext_class, g_mbrext);

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