The Design and Implementation of the FreeBSD Operating System, Second Edition
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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/5.4/sys/geom/geom_mbr.c 145335 2005-04-20 19:11:07Z cvs2svn $");
   35 
   36 #include <sys/param.h>
   37 #include <sys/errno.h>
   38 #include <sys/endian.h>
   39 #include <sys/systm.h>
   40 #include <sys/kernel.h>
   41 #include <sys/fcntl.h>
   42 #include <sys/malloc.h>
   43 #include <sys/bio.h>
   44 #include <sys/lock.h>
   45 #include <sys/mutex.h>
   46 #include <sys/md5.h>
   47 
   48 #include <sys/diskmbr.h>
   49 #include <sys/sbuf.h>
   50 #include <geom/geom.h>
   51 #include <geom/geom_slice.h>
   52 
   53 #define MBR_CLASS_NAME "MBR"
   54 #define MBREXT_CLASS_NAME "MBREXT"
   55 
   56 static struct dos_partition historical_bogus_partition_table[NDOSPART] = {
   57         { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
   58         { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
   59         { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
   60         { 0x80, 0, 1, 0, DOSPTYP_386BSD, 255, 255, 255, 0, 50000, },
   61 };
   62 
   63 static struct dos_partition historical_bogus_partition_table_fixed[NDOSPART] = {
   64         { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
   65         { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
   66         { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
   67         { 0x80, 0, 1, 0, DOSPTYP_386BSD, 254, 255, 255, 0, 50000, },
   68 };
   69 
   70 static void
   71 g_mbr_print(int i, struct dos_partition *dp)
   72 {
   73 
   74         printf("[%d] f:%02x typ:%d", i, dp->dp_flag, dp->dp_typ);
   75         printf(" s(CHS):%d/%d/%d", DPCYL(dp->dp_scyl, dp->dp_ssect),
   76             dp->dp_shd, DPSECT(dp->dp_ssect));
   77         printf(" e(CHS):%d/%d/%d", DPCYL(dp->dp_ecyl, dp->dp_esect),
   78             dp->dp_ehd, DPSECT(dp->dp_esect));
   79         printf(" s:%d l:%d\n", dp->dp_start, dp->dp_size);
   80 }
   81 
   82 struct g_mbr_softc {
   83         int             type [NDOSPART];
   84         u_int           sectorsize;
   85         u_char          sec0[512];
   86         u_char          slicesum[16];
   87 };
   88 
   89 static int
   90 g_mbr_modify(struct g_geom *gp, struct g_mbr_softc *ms, u_char *sec0)
   91 {
   92         int i, error;
   93         off_t l[NDOSPART];
   94         struct dos_partition ndp[NDOSPART], *dp;
   95         MD5_CTX md5sum;
   96 
   97         g_topology_assert();
   98 
   99         if (sec0[0x1fe] != 0x55 && sec0[0x1ff] != 0xaa)
  100                 return (EBUSY);
  101 
  102         dp = ndp;
  103         for (i = 0; i < NDOSPART; i++) {
  104                 dos_partition_dec(
  105                     sec0 + DOSPARTOFF + i * sizeof(struct dos_partition),
  106                     dp + i);
  107                 if (bootverbose)
  108                         g_mbr_print(i, dp + i);
  109         }
  110         if ((!bcmp(dp, historical_bogus_partition_table,
  111             sizeof historical_bogus_partition_table)) ||
  112             (!bcmp(dp, historical_bogus_partition_table_fixed,
  113             sizeof historical_bogus_partition_table_fixed))) {
  114                 /*
  115                  * We will not allow people to write these from "the inside",
  116                  * Since properly selfdestructing takes too much code.  If 
  117                  * people really want to do this, they cannot have any
  118                  * providers of this geom open, and in that case they can just
  119                  * as easily overwrite the MBR in the parent device.
  120                  */
  121                 return(EBUSY);
  122         }
  123         for (i = 0; i < NDOSPART; i++) {
  124                 /* 
  125                  * A Protective MBR (PMBR) has a single partition of
  126                  * type 0xEE spanning the whole disk. Such a MBR
  127                  * protects a GPT on the disk from MBR tools that
  128                  * don't know anything about GPT. We're interpreting
  129                  * it a bit more loosely: any partition of type 0xEE
  130                  * is to be skipped as it doesn't contain any data
  131                  * that we should care about. We still allow other
  132                  * partitions to be present in the MBR. A PMBR will
  133                  * be handled correctly anyway.
  134                  */
  135                 if (dp[i].dp_typ == DOSPTYP_PMBR)
  136                         l[i] = 0;
  137                 else if (dp[i].dp_flag != 0 && dp[i].dp_flag != 0x80)
  138                         l[i] = 0;
  139                 else if (dp[i].dp_typ == 0)
  140                         l[i] = 0;
  141                 else
  142                         l[i] = (off_t)dp[i].dp_size * ms->sectorsize;
  143                 error = g_slice_config(gp, i, G_SLICE_CONFIG_CHECK,
  144                     (off_t)dp[i].dp_start * ms->sectorsize, l[i],
  145                     ms->sectorsize, "%ss%d", gp->name, 1 + i);
  146                 if (error)
  147                         return (error);
  148         }
  149         for (i = 0; i < NDOSPART; i++) {
  150                 ms->type[i] = dp[i].dp_typ;
  151                 g_slice_config(gp, i, G_SLICE_CONFIG_SET,
  152                     (off_t)dp[i].dp_start * ms->sectorsize, l[i],
  153                     ms->sectorsize, "%ss%d", gp->name, 1 + i);
  154         }
  155         bcopy(sec0, ms->sec0, 512);
  156 
  157         /*
  158          * Calculate MD5 from the first sector and use it for avoiding
  159          * recursive slices creation.
  160          */
  161         MD5Init(&md5sum);
  162         MD5Update(&md5sum, ms->sec0, sizeof(ms->sec0));
  163         MD5Final(ms->slicesum, &md5sum);
  164 
  165         return (0);
  166 }
  167 
  168 static int
  169 g_mbr_ioctl(struct g_provider *pp, u_long cmd, void *data, int fflag, struct thread *td)
  170 {
  171         struct g_geom *gp;
  172         struct g_mbr_softc *ms;
  173         struct g_slicer *gsp;
  174         struct g_consumer *cp;
  175         int error;
  176 
  177         gp = pp->geom;
  178         gsp = gp->softc;
  179         ms = gsp->softc;
  180 
  181         switch(cmd) {
  182         case DIOCSMBR: {
  183                 if (!(fflag & FWRITE))
  184                         return (EPERM);
  185                 DROP_GIANT();
  186                 g_topology_lock();
  187                 /* Validate and modify our slicer instance to match. */
  188                 error = g_mbr_modify(gp, ms, data);
  189                 cp = LIST_FIRST(&gp->consumer);
  190                 error = g_write_data(cp, 0, data, 512);
  191                 g_topology_unlock();
  192                 PICKUP_GIANT();
  193                 return(error);
  194         }
  195         default:
  196                 return (ENOIOCTL);
  197         }
  198 }
  199 
  200 static int
  201 g_mbr_start(struct bio *bp)
  202 {
  203         struct g_provider *pp;
  204         struct g_geom *gp;
  205         struct g_mbr_softc *mp;
  206         struct g_slicer *gsp;
  207         int idx;
  208 
  209         pp = bp->bio_to;
  210         idx = pp->index;
  211         gp = pp->geom;
  212         gsp = gp->softc;
  213         mp = gsp->softc;
  214         if (bp->bio_cmd == BIO_GETATTR) {
  215                 if (g_handleattr_int(bp, "MBR::type", mp->type[idx]))
  216                         return (1);
  217                 if (g_handleattr_off_t(bp, "MBR::offset",
  218                     gsp->slices[idx].offset))
  219                         return (1);
  220                 if (g_handleattr(bp, "MBR::slicesum", mp->slicesum,
  221                     sizeof(mp->slicesum)))
  222                         return (1);
  223         }
  224 
  225         return (0);
  226 }
  227 
  228 static void
  229 g_mbr_dumpconf(struct sbuf *sb, const char *indent, struct g_geom *gp, struct g_consumer *cp __unused, struct g_provider *pp)
  230 {
  231         struct g_mbr_softc *mp;
  232         struct g_slicer *gsp;
  233 
  234         gsp = gp->softc;
  235         mp = gsp->softc;
  236         g_slice_dumpconf(sb, indent, gp, cp, pp);
  237         if (pp != NULL) {
  238                 if (indent == NULL)
  239                         sbuf_printf(sb, " ty %d", mp->type[pp->index]);
  240                 else
  241                         sbuf_printf(sb, "%s<type>%d</type>\n", indent,
  242                             mp->type[pp->index]);
  243         }
  244 }
  245 
  246 static struct g_geom *
  247 g_mbr_taste(struct g_class *mp, struct g_provider *pp, int insist)
  248 {
  249         struct g_geom *gp;
  250         struct g_consumer *cp;
  251         int error;
  252         struct g_mbr_softc *ms;
  253         u_int fwsectors, sectorsize;
  254         u_char *buf;
  255         u_char hash[16];
  256         MD5_CTX md5sum;
  257 
  258         g_trace(G_T_TOPOLOGY, "mbr_taste(%s,%s)", mp->name, pp->name);
  259         g_topology_assert();
  260         gp = g_slice_new(mp, NDOSPART, pp, &cp, &ms, sizeof *ms, g_mbr_start);
  261         if (gp == NULL)
  262                 return (NULL);
  263         g_topology_unlock();
  264         do {
  265                 error = g_getattr("GEOM::fwsectors", cp, &fwsectors);
  266                 if (error)
  267                         fwsectors = 17;
  268                 sectorsize = cp->provider->sectorsize;
  269                 if (sectorsize < 512)
  270                         break;
  271                 ms->sectorsize = sectorsize;
  272                 buf = g_read_data(cp, 0, sectorsize, &error);
  273                 if (buf == NULL || error != 0)
  274                         break;
  275 
  276                 /*
  277                  * Calculate MD5 from the first sector and use it for avoiding
  278                  * recursive slices creation.
  279                  */
  280                 bcopy(buf, ms->sec0, 512);
  281                 MD5Init(&md5sum);
  282                 MD5Update(&md5sum, ms->sec0, sizeof(ms->sec0));
  283                 MD5Final(ms->slicesum, &md5sum);
  284 
  285                 error = g_getattr("MBR::slicesum", cp, &hash);
  286                 if (!error && !bcmp(ms->slicesum, hash, sizeof(hash))) {
  287                         g_free(buf);
  288                         break;
  289                 }
  290 
  291                 g_topology_lock();
  292                 g_mbr_modify(gp, ms, buf);
  293                 g_topology_unlock();
  294                 g_free(buf);
  295                 break;
  296         } while (0);
  297         g_topology_lock();
  298         g_access(cp, -1, 0, 0);
  299         if (LIST_EMPTY(&gp->provider)) {
  300                 g_slice_spoiled(cp);
  301                 return (NULL);
  302         }
  303         return (gp);
  304 }
  305 
  306 static struct g_class g_mbr_class       = {
  307         .name = MBR_CLASS_NAME,
  308         .version = G_VERSION,
  309         .taste = g_mbr_taste,
  310         .dumpconf = g_mbr_dumpconf,
  311         .ioctl = g_mbr_ioctl,
  312 };
  313 
  314 DECLARE_GEOM_CLASS(g_mbr_class, g_mbr);
  315 
  316 #define NDOSEXTPART             32
  317 struct g_mbrext_softc {
  318         int             type [NDOSEXTPART];
  319 };
  320 
  321 static int
  322 g_mbrext_start(struct bio *bp)
  323 {
  324         struct g_provider *pp;
  325         struct g_geom *gp;
  326         struct g_mbrext_softc *mp;
  327         struct g_slicer *gsp;
  328         int idx;
  329 
  330         pp = bp->bio_to;
  331         idx = pp->index;
  332         gp = pp->geom;
  333         gsp = gp->softc;
  334         mp = gsp->softc;
  335         if (bp->bio_cmd == BIO_GETATTR) {
  336                 if (g_handleattr_int(bp, "MBR::type", mp->type[idx]))
  337                         return (1);
  338         }
  339         return (0);
  340 }
  341 
  342 static void
  343 g_mbrext_dumpconf(struct sbuf *sb, const char *indent, struct g_geom *gp, struct g_consumer *cp __unused, struct g_provider *pp)
  344 {
  345         struct g_mbrext_softc *mp;
  346         struct g_slicer *gsp;
  347 
  348         g_slice_dumpconf(sb, indent, gp, cp, pp);
  349         gsp = gp->softc;
  350         mp = gsp->softc;
  351         if (pp != NULL) {
  352                 if (indent == NULL)
  353                         sbuf_printf(sb, " ty %d", mp->type[pp->index]);
  354                 else
  355                         sbuf_printf(sb, "%s<type>%d</type>\n", indent,
  356                             mp->type[pp->index]);
  357         }
  358 }
  359 
  360 static struct g_geom *
  361 g_mbrext_taste(struct g_class *mp, struct g_provider *pp, int insist __unused)
  362 {
  363         struct g_geom *gp;
  364         struct g_consumer *cp;
  365         int error, i, slice;
  366         struct g_mbrext_softc *ms;
  367         off_t off;
  368         u_char *buf;
  369         struct dos_partition dp[4];
  370         u_int fwsectors, sectorsize;
  371 
  372         g_trace(G_T_TOPOLOGY, "g_mbrext_taste(%s,%s)", mp->name, pp->name);
  373         g_topology_assert();
  374         if (strcmp(pp->geom->class->name, MBR_CLASS_NAME))
  375                 return (NULL);
  376         gp = g_slice_new(mp, NDOSEXTPART, pp, &cp, &ms, sizeof *ms,
  377             g_mbrext_start);
  378         if (gp == NULL)
  379                 return (NULL);
  380         g_topology_unlock();
  381         off = 0;
  382         slice = 0;
  383         do {
  384                 error = g_getattr("MBR::type", cp, &i);
  385                 if (error || (i != DOSPTYP_EXT && i != DOSPTYP_EXTLBA))
  386                         break;
  387                 error = g_getattr("GEOM::fwsectors", cp, &fwsectors);
  388                 if (error)
  389                         fwsectors = 17;
  390                 sectorsize = cp->provider->sectorsize;
  391                 if (sectorsize != 512)
  392                         break;
  393                 for (;;) {
  394                         buf = g_read_data(cp, off, sectorsize, &error);
  395                         if (buf == NULL || error != 0)
  396                                 break;
  397                         if (buf[0x1fe] != 0x55 && buf[0x1ff] != 0xaa) {
  398                                 g_free(buf);
  399                                 break;
  400                         }
  401                         for (i = 0; i < NDOSPART; i++) 
  402                                 dos_partition_dec(
  403                                     buf + DOSPARTOFF + 
  404                                     i * sizeof(struct dos_partition), dp + i);
  405                         g_free(buf);
  406                         if (bootverbose) {
  407                                 printf("MBREXT Slice %d on %s:\n",
  408                                     slice + 5, gp->name);
  409                                 g_mbr_print(0, dp);
  410                                 g_mbr_print(1, dp + 1);
  411                         }
  412                         if ((dp[0].dp_flag & 0x7f) == 0 &&
  413                              dp[0].dp_size != 0 && dp[0].dp_typ != 0) {
  414                                 g_topology_lock();
  415                                 g_slice_config(gp, slice, G_SLICE_CONFIG_SET,
  416                                     (((off_t)dp[0].dp_start) << 9ULL) + off,
  417                                     ((off_t)dp[0].dp_size) << 9ULL,
  418                                     sectorsize,
  419                                     "%*.*s%d",
  420                                     strlen(gp->name) - 1,
  421                                     strlen(gp->name) - 1,
  422                                     gp->name,
  423                                     slice + 5);
  424                                 g_topology_unlock();
  425                                 ms->type[slice] = dp[0].dp_typ;
  426                                 slice++;
  427                         }
  428                         if (dp[1].dp_flag != 0)
  429                                 break;
  430                         if (dp[1].dp_typ != DOSPTYP_EXT &&
  431                             dp[1].dp_typ != DOSPTYP_EXTLBA)
  432                                 break;
  433                         if (dp[1].dp_size == 0)
  434                                 break;
  435                         off = ((off_t)dp[1].dp_start) << 9ULL;
  436                 }
  437                 break;
  438         } while (0);
  439         g_topology_lock();
  440         g_access(cp, -1, 0, 0);
  441         if (LIST_EMPTY(&gp->provider)) {
  442                 g_slice_spoiled(cp);
  443                 return (NULL);
  444         }
  445         return (gp);
  446 }
  447 
  448 
  449 static struct g_class g_mbrext_class    = {
  450         .name = MBREXT_CLASS_NAME,
  451         .version = G_VERSION,
  452         .taste = g_mbrext_taste,
  453         .dumpconf = g_mbrext_dumpconf,
  454 };
  455 
  456 DECLARE_GEOM_CLASS(g_mbrext_class, g_mbrext);

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