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/9.0/sys/geom/geom_mbr.c 219029 2011-02-25 10:24:35Z netchild $");
   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 
   49 #include <sys/diskmbr.h>
   50 #include <sys/sbuf.h>
   51 #include <geom/geom.h>
   52 #include <geom/geom_slice.h>
   53 
   54 FEATURE(geom_mbr, "GEOM DOS/MBR partitioning support");
   55 
   56 #define MBR_CLASS_NAME "MBR"
   57 #define MBREXT_CLASS_NAME "MBREXT"
   58 
   59 static struct dos_partition historical_bogus_partition_table[NDOSPART] = {
   60         { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
   61         { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
   62         { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
   63         { 0x80, 0, 1, 0, DOSPTYP_386BSD, 255, 255, 255, 0, 50000, },
   64 };
   65 
   66 static struct dos_partition historical_bogus_partition_table_fixed[NDOSPART] = {
   67         { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
   68         { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
   69         { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
   70         { 0x80, 0, 1, 0, DOSPTYP_386BSD, 254, 255, 255, 0, 50000, },
   71 };
   72 
   73 static void
   74 g_mbr_print(int i, struct dos_partition *dp)
   75 {
   76 
   77         printf("[%d] f:%02x typ:%d", i, dp->dp_flag, dp->dp_typ);
   78         printf(" s(CHS):%d/%d/%d", DPCYL(dp->dp_scyl, dp->dp_ssect),
   79             dp->dp_shd, DPSECT(dp->dp_ssect));
   80         printf(" e(CHS):%d/%d/%d", DPCYL(dp->dp_ecyl, dp->dp_esect),
   81             dp->dp_ehd, DPSECT(dp->dp_esect));
   82         printf(" s:%d l:%d\n", dp->dp_start, dp->dp_size);
   83 }
   84 
   85 struct g_mbr_softc {
   86         int             type [NDOSPART];
   87         u_int           sectorsize;
   88         u_char          sec0[512];
   89         u_char          slicesum[16];
   90 };
   91 
   92 /*
   93  * XXX: Add gctl_req arg and give good error msgs.
   94  * XXX: Check that length argument does not bring boot code inside any slice.
   95  */
   96 static int
   97 g_mbr_modify(struct g_geom *gp, struct g_mbr_softc *ms, u_char *sec0, int len __unused)
   98 {
   99         int i, error;
  100         off_t l[NDOSPART];
  101         struct dos_partition ndp[NDOSPART], *dp;
  102         MD5_CTX md5sum;
  103 
  104         g_topology_assert();
  105 
  106         if (sec0[0x1fe] != 0x55 && sec0[0x1ff] != 0xaa)
  107                 return (EBUSY);
  108 
  109         dp = ndp;
  110         for (i = 0; i < NDOSPART; i++) {
  111                 dos_partition_dec(
  112                     sec0 + DOSPARTOFF + i * sizeof(struct dos_partition),
  113                     dp + i);
  114         }
  115         if ((!bcmp(dp, historical_bogus_partition_table,
  116             sizeof historical_bogus_partition_table)) ||
  117             (!bcmp(dp, historical_bogus_partition_table_fixed,
  118             sizeof historical_bogus_partition_table_fixed))) {
  119                 /*
  120                  * We will not allow people to write these from "the inside",
  121                  * Since properly selfdestructing takes too much code.  If 
  122                  * people really want to do this, they cannot have any
  123                  * providers of this geom open, and in that case they can just
  124                  * as easily overwrite the MBR in the parent device.
  125                  */
  126                 return(EBUSY);
  127         }
  128         for (i = 0; i < NDOSPART; i++) {
  129                 /* 
  130                  * A Protective MBR (PMBR) has a single partition of
  131                  * type 0xEE spanning the whole disk. Such a MBR
  132                  * protects a GPT on the disk from MBR tools that
  133                  * don't know anything about GPT. We're interpreting
  134                  * it a bit more loosely: any partition of type 0xEE
  135                  * is to be skipped as it doesn't contain any data
  136                  * that we should care about. We still allow other
  137                  * partitions to be present in the MBR. A PMBR will
  138                  * be handled correctly anyway.
  139                  */
  140                 if (dp[i].dp_typ == DOSPTYP_PMBR)
  141                         l[i] = 0;
  142                 else if (dp[i].dp_flag != 0 && dp[i].dp_flag != 0x80)
  143                         l[i] = 0;
  144                 else if (dp[i].dp_typ == 0)
  145                         l[i] = 0;
  146                 else
  147                         l[i] = (off_t)dp[i].dp_size * ms->sectorsize;
  148                 error = g_slice_config(gp, i, G_SLICE_CONFIG_CHECK,
  149                     (off_t)dp[i].dp_start * ms->sectorsize, l[i],
  150                     ms->sectorsize, "%ss%d", gp->name, 1 + i);
  151                 if (error)
  152                         return (error);
  153         }
  154         for (i = 0; i < NDOSPART; i++) {
  155                 ms->type[i] = dp[i].dp_typ;
  156                 g_slice_config(gp, i, G_SLICE_CONFIG_SET,
  157                     (off_t)dp[i].dp_start * ms->sectorsize, l[i],
  158                     ms->sectorsize, "%ss%d", gp->name, 1 + i);
  159         }
  160         bcopy(sec0, ms->sec0, 512);
  161 
  162         /*
  163          * Calculate MD5 from the first sector and use it for avoiding
  164          * recursive slices creation.
  165          */
  166         MD5Init(&md5sum);
  167         MD5Update(&md5sum, ms->sec0, sizeof(ms->sec0));
  168         MD5Final(ms->slicesum, &md5sum);
  169 
  170         return (0);
  171 }
  172 
  173 static int
  174 g_mbr_ioctl(struct g_provider *pp, u_long cmd, void *data, int fflag, struct thread *td)
  175 {
  176         struct g_geom *gp;
  177         struct g_mbr_softc *ms;
  178         struct g_slicer *gsp;
  179         struct g_consumer *cp;
  180         int error, opened;
  181 
  182         gp = pp->geom;
  183         gsp = gp->softc;
  184         ms = gsp->softc;
  185 
  186         opened = 0;
  187         error = 0;
  188         switch(cmd) {
  189         case DIOCSMBR: {
  190                 if (!(fflag & FWRITE))
  191                         return (EPERM);
  192                 DROP_GIANT();
  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                 PICKUP_GIANT();
  208                 return(error);
  209         }
  210         default:
  211                 return (ENOIOCTL);
  212         }
  213 }
  214 
  215 static int
  216 g_mbr_start(struct bio *bp)
  217 {
  218         struct g_provider *pp;
  219         struct g_geom *gp;
  220         struct g_mbr_softc *mp;
  221         struct g_slicer *gsp;
  222         int idx;
  223 
  224         pp = bp->bio_to;
  225         idx = pp->index;
  226         gp = pp->geom;
  227         gsp = gp->softc;
  228         mp = gsp->softc;
  229         if (bp->bio_cmd == BIO_GETATTR) {
  230                 if (g_handleattr_int(bp, "MBR::type", mp->type[idx]))
  231                         return (1);
  232                 if (g_handleattr_off_t(bp, "MBR::offset",
  233                     gsp->slices[idx].offset))
  234                         return (1);
  235                 if (g_handleattr(bp, "MBR::slicesum", mp->slicesum,
  236                     sizeof(mp->slicesum)))
  237                         return (1);
  238         }
  239 
  240         return (0);
  241 }
  242 
  243 static void
  244 g_mbr_dumpconf(struct sbuf *sb, const char *indent, struct g_geom *gp, struct g_consumer *cp __unused, struct g_provider *pp)
  245 {
  246         struct g_mbr_softc *mp;
  247         struct g_slicer *gsp;
  248 
  249         gsp = gp->softc;
  250         mp = gsp->softc;
  251         g_slice_dumpconf(sb, indent, gp, cp, pp);
  252         if (pp != NULL) {
  253                 if (indent == NULL)
  254                         sbuf_printf(sb, " ty %d", mp->type[pp->index]);
  255                 else
  256                         sbuf_printf(sb, "%s<type>%d</type>\n", indent,
  257                             mp->type[pp->index]);
  258         }
  259 }
  260 
  261 static struct g_geom *
  262 g_mbr_taste(struct g_class *mp, struct g_provider *pp, int insist)
  263 {
  264         struct g_geom *gp;
  265         struct g_consumer *cp;
  266         int error;
  267         struct g_mbr_softc *ms;
  268         u_int fwsectors, sectorsize;
  269         u_char *buf;
  270         u_char hash[16];
  271         MD5_CTX md5sum;
  272 
  273         g_trace(G_T_TOPOLOGY, "mbr_taste(%s,%s)", mp->name, pp->name);
  274         g_topology_assert();
  275         if (!strcmp(pp->geom->class->name, MBR_CLASS_NAME))
  276                 return (NULL);
  277         gp = g_slice_new(mp, NDOSPART, pp, &cp, &ms, sizeof *ms, g_mbr_start);
  278         if (gp == NULL)
  279                 return (NULL);
  280         g_topology_unlock();
  281         do {
  282                 error = g_getattr("GEOM::fwsectors", cp, &fwsectors);
  283                 if (error)
  284                         fwsectors = 17;
  285                 sectorsize = cp->provider->sectorsize;
  286                 if (sectorsize < 512)
  287                         break;
  288                 ms->sectorsize = sectorsize;
  289                 buf = g_read_data(cp, 0, sectorsize, NULL);
  290                 if (buf == NULL)
  291                         break;
  292 
  293                 /*
  294                  * Calculate MD5 from the first sector and use it for avoiding
  295                  * recursive slices creation.
  296                  */
  297                 bcopy(buf, ms->sec0, 512);
  298                 MD5Init(&md5sum);
  299                 MD5Update(&md5sum, ms->sec0, sizeof(ms->sec0));
  300                 MD5Final(ms->slicesum, &md5sum);
  301 
  302                 error = g_getattr("MBR::slicesum", cp, &hash);
  303                 if (!error && !bcmp(ms->slicesum, hash, sizeof(hash))) {
  304                         g_free(buf);
  305                         break;
  306                 }
  307 
  308                 g_topology_lock();
  309                 g_mbr_modify(gp, ms, buf, 512);
  310                 g_topology_unlock();
  311                 g_free(buf);
  312                 break;
  313         } while (0);
  314         g_topology_lock();
  315         g_access(cp, -1, 0, 0);
  316         if (LIST_EMPTY(&gp->provider)) {
  317                 g_slice_spoiled(cp);
  318                 return (NULL);
  319         }
  320         return (gp);
  321 }
  322 
  323 static void
  324 g_mbr_config(struct gctl_req *req, struct g_class *mp, const char *verb)
  325 {
  326         struct g_geom *gp;
  327         struct g_consumer *cp;
  328         struct g_mbr_softc *ms;
  329         struct g_slicer *gsp;
  330         int opened = 0, error = 0;
  331         void *data;
  332         int len;
  333 
  334         g_topology_assert();
  335         gp = gctl_get_geom(req, mp, "geom");
  336         if (gp == NULL)
  337                 return;
  338         if (strcmp(verb, "write MBR")) {
  339                 gctl_error(req, "Unknown verb");
  340                 return;
  341         }
  342         gsp = gp->softc;
  343         ms = gsp->softc;
  344         data = gctl_get_param(req, "data", &len);
  345         if (data == NULL)
  346                 return;
  347         if (len < 512 || (len % 512)) {
  348                 gctl_error(req, "Wrong request length");
  349                 return;
  350         }
  351         cp = LIST_FIRST(&gp->consumer);
  352         if (cp->acw == 0) {
  353                 error = g_access(cp, 0, 1, 0);
  354                 if (error == 0)
  355                         opened = 1;
  356         }
  357         if (!error)
  358                 error = g_mbr_modify(gp, ms, data, len);
  359         if (error)
  360                 gctl_error(req, "conflict with open slices");
  361         if (!error)
  362                 error = g_write_data(cp, 0, data, len);
  363         if (error)
  364                 gctl_error(req, "sector zero write failed");
  365         if (opened)
  366                 g_access(cp, 0, -1 , 0);
  367         return;
  368 }
  369 
  370 static struct g_class g_mbr_class       = {
  371         .name = MBR_CLASS_NAME,
  372         .version = G_VERSION,
  373         .taste = g_mbr_taste,
  374         .dumpconf = g_mbr_dumpconf,
  375         .ctlreq = g_mbr_config,
  376         .ioctl = g_mbr_ioctl,
  377 };
  378 
  379 DECLARE_GEOM_CLASS(g_mbr_class, g_mbr);
  380 
  381 #define NDOSEXTPART             32
  382 struct g_mbrext_softc {
  383         int             type [NDOSEXTPART];
  384 };
  385 
  386 static int
  387 g_mbrext_start(struct bio *bp)
  388 {
  389         struct g_provider *pp;
  390         struct g_geom *gp;
  391         struct g_mbrext_softc *mp;
  392         struct g_slicer *gsp;
  393         int idx;
  394 
  395         pp = bp->bio_to;
  396         idx = pp->index;
  397         gp = pp->geom;
  398         gsp = gp->softc;
  399         mp = gsp->softc;
  400         if (bp->bio_cmd == BIO_GETATTR) {
  401                 if (g_handleattr_int(bp, "MBR::type", mp->type[idx]))
  402                         return (1);
  403         }
  404         return (0);
  405 }
  406 
  407 static void
  408 g_mbrext_dumpconf(struct sbuf *sb, const char *indent, struct g_geom *gp, struct g_consumer *cp __unused, struct g_provider *pp)
  409 {
  410         struct g_mbrext_softc *mp;
  411         struct g_slicer *gsp;
  412 
  413         g_slice_dumpconf(sb, indent, gp, cp, pp);
  414         gsp = gp->softc;
  415         mp = gsp->softc;
  416         if (pp != NULL) {
  417                 if (indent == NULL)
  418                         sbuf_printf(sb, " ty %d", mp->type[pp->index]);
  419                 else
  420                         sbuf_printf(sb, "%s<type>%d</type>\n", indent,
  421                             mp->type[pp->index]);
  422         }
  423 }
  424 
  425 static struct g_geom *
  426 g_mbrext_taste(struct g_class *mp, struct g_provider *pp, int insist __unused)
  427 {
  428         struct g_geom *gp;
  429         struct g_consumer *cp;
  430         int error, i, slice;
  431         struct g_mbrext_softc *ms;
  432         off_t off;
  433         u_char *buf;
  434         struct dos_partition dp[4];
  435         u_int fwsectors, sectorsize;
  436 
  437         g_trace(G_T_TOPOLOGY, "g_mbrext_taste(%s,%s)", mp->name, pp->name);
  438         g_topology_assert();
  439         if (strcmp(pp->geom->class->name, MBR_CLASS_NAME))
  440                 return (NULL);
  441         gp = g_slice_new(mp, NDOSEXTPART, pp, &cp, &ms, sizeof *ms,
  442             g_mbrext_start);
  443         if (gp == NULL)
  444                 return (NULL);
  445         g_topology_unlock();
  446         off = 0;
  447         slice = 0;
  448         do {
  449                 error = g_getattr("MBR::type", cp, &i);
  450                 if (error || (i != DOSPTYP_EXT && i != DOSPTYP_EXTLBA))
  451                         break;
  452                 error = g_getattr("GEOM::fwsectors", cp, &fwsectors);
  453                 if (error)
  454                         fwsectors = 17;
  455                 sectorsize = cp->provider->sectorsize;
  456                 if (sectorsize != 512)
  457                         break;
  458                 for (;;) {
  459                         buf = g_read_data(cp, off, sectorsize, NULL);
  460                         if (buf == NULL)
  461                                 break;
  462                         if (buf[0x1fe] != 0x55 && buf[0x1ff] != 0xaa) {
  463                                 g_free(buf);
  464                                 break;
  465                         }
  466                         for (i = 0; i < NDOSPART; i++) 
  467                                 dos_partition_dec(
  468                                     buf + DOSPARTOFF + 
  469                                     i * sizeof(struct dos_partition), dp + i);
  470                         g_free(buf);
  471                         if (0 && bootverbose) {
  472                                 printf("MBREXT Slice %d on %s:\n",
  473                                     slice + 5, gp->name);
  474                                 g_mbr_print(0, dp);
  475                                 g_mbr_print(1, dp + 1);
  476                         }
  477                         if ((dp[0].dp_flag & 0x7f) == 0 &&
  478                              dp[0].dp_size != 0 && dp[0].dp_typ != 0) {
  479                                 g_topology_lock();
  480                                 g_slice_config(gp, slice, G_SLICE_CONFIG_SET,
  481                                     (((off_t)dp[0].dp_start) << 9ULL) + off,
  482                                     ((off_t)dp[0].dp_size) << 9ULL,
  483                                     sectorsize,
  484                                     "%*.*s%d",
  485                                     strlen(gp->name) - 1,
  486                                     strlen(gp->name) - 1,
  487                                     gp->name,
  488                                     slice + 5);
  489                                 g_topology_unlock();
  490                                 ms->type[slice] = dp[0].dp_typ;
  491                                 slice++;
  492                         }
  493                         if (dp[1].dp_flag != 0)
  494                                 break;
  495                         if (dp[1].dp_typ != DOSPTYP_EXT &&
  496                             dp[1].dp_typ != DOSPTYP_EXTLBA)
  497                                 break;
  498                         if (dp[1].dp_size == 0)
  499                                 break;
  500                         off = ((off_t)dp[1].dp_start) << 9ULL;
  501                 }
  502                 break;
  503         } while (0);
  504         g_topology_lock();
  505         g_access(cp, -1, 0, 0);
  506         if (LIST_EMPTY(&gp->provider)) {
  507                 g_slice_spoiled(cp);
  508                 return (NULL);
  509         }
  510         return (gp);
  511 }
  512 
  513 
  514 static struct g_class g_mbrext_class    = {
  515         .name = MBREXT_CLASS_NAME,
  516         .version = G_VERSION,
  517         .taste = g_mbrext_taste,
  518         .dumpconf = g_mbrext_dumpconf,
  519 };
  520 
  521 DECLARE_GEOM_CLASS(g_mbrext_class, g_mbrext);

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