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/8.4/sys/geom/geom_mbr.c 235502 2012-05-16 09:03:29Z avg $");
   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 #include <sys/proc.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 #define MBR_CLASS_NAME "MBR"
   55 #define MBREXT_CLASS_NAME "MBREXT"
   56 
   57 static struct dos_partition historical_bogus_partition_table[NDOSPART] = {
   58         { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
   59         { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
   60         { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
   61         { 0x80, 0, 1, 0, DOSPTYP_386BSD, 255, 255, 255, 0, 50000, },
   62 };
   63 
   64 static struct dos_partition historical_bogus_partition_table_fixed[NDOSPART] = {
   65         { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
   66         { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
   67         { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
   68         { 0x80, 0, 1, 0, DOSPTYP_386BSD, 254, 255, 255, 0, 50000, },
   69 };
   70 
   71 static void
   72 g_mbr_print(int i, struct dos_partition *dp)
   73 {
   74 
   75         printf("[%d] f:%02x typ:%d", i, dp->dp_flag, dp->dp_typ);
   76         printf(" s(CHS):%d/%d/%d", DPCYL(dp->dp_scyl, dp->dp_ssect),
   77             dp->dp_shd, DPSECT(dp->dp_ssect));
   78         printf(" e(CHS):%d/%d/%d", DPCYL(dp->dp_ecyl, dp->dp_esect),
   79             dp->dp_ehd, DPSECT(dp->dp_esect));
   80         printf(" s:%d l:%d\n", dp->dp_start, dp->dp_size);
   81 }
   82 
   83 struct g_mbr_softc {
   84         int             type [NDOSPART];
   85         u_int           sectorsize;
   86         u_char          sec0[512];
   87         u_char          slicesum[16];
   88 };
   89 
   90 /*
   91  * XXX: Add gctl_req arg and give good error msgs.
   92  * XXX: Check that length argument does not bring boot code inside any slice.
   93  */
   94 static int
   95 g_mbr_modify(struct g_geom *gp, struct g_mbr_softc *ms, u_char *sec0, int len __unused)
   96 {
   97         int i, error;
   98         off_t l[NDOSPART];
   99         struct dos_partition ndp[NDOSPART], *dp;
  100         MD5_CTX md5sum;
  101 
  102         g_topology_assert();
  103 
  104         if (sec0[0x1fe] != 0x55 && sec0[0x1ff] != 0xaa)
  105                 return (EBUSY);
  106 
  107         dp = ndp;
  108         for (i = 0; i < NDOSPART; i++) {
  109                 dos_partition_dec(
  110                     sec0 + DOSPARTOFF + i * sizeof(struct dos_partition),
  111                     dp + i);
  112         }
  113         if ((!bcmp(dp, historical_bogus_partition_table,
  114             sizeof historical_bogus_partition_table)) ||
  115             (!bcmp(dp, historical_bogus_partition_table_fixed,
  116             sizeof historical_bogus_partition_table_fixed))) {
  117                 /*
  118                  * We will not allow people to write these from "the inside",
  119                  * Since properly selfdestructing takes too much code.  If 
  120                  * people really want to do this, they cannot have any
  121                  * providers of this geom open, and in that case they can just
  122                  * as easily overwrite the MBR in the parent device.
  123                  */
  124                 return(EBUSY);
  125         }
  126         for (i = 0; i < NDOSPART; i++) {
  127                 /* 
  128                  * A Protective MBR (PMBR) has a single partition of
  129                  * type 0xEE spanning the whole disk. Such a MBR
  130                  * protects a GPT on the disk from MBR tools that
  131                  * don't know anything about GPT. We're interpreting
  132                  * it a bit more loosely: any partition of type 0xEE
  133                  * is to be skipped as it doesn't contain any data
  134                  * that we should care about. We still allow other
  135                  * partitions to be present in the MBR. A PMBR will
  136                  * be handled correctly anyway.
  137                  */
  138                 if (dp[i].dp_typ == DOSPTYP_PMBR)
  139                         l[i] = 0;
  140                 else if (dp[i].dp_flag != 0 && dp[i].dp_flag != 0x80)
  141                         l[i] = 0;
  142                 else if (dp[i].dp_typ == 0)
  143                         l[i] = 0;
  144                 else
  145                         l[i] = (off_t)dp[i].dp_size * ms->sectorsize;
  146                 error = g_slice_config(gp, i, G_SLICE_CONFIG_CHECK,
  147                     (off_t)dp[i].dp_start * ms->sectorsize, l[i],
  148                     ms->sectorsize, "%ss%d", gp->name, 1 + i);
  149                 if (error)
  150                         return (error);
  151         }
  152         for (i = 0; i < NDOSPART; i++) {
  153                 ms->type[i] = dp[i].dp_typ;
  154                 g_slice_config(gp, i, G_SLICE_CONFIG_SET,
  155                     (off_t)dp[i].dp_start * ms->sectorsize, l[i],
  156                     ms->sectorsize, "%ss%d", gp->name, 1 + i);
  157         }
  158         bcopy(sec0, ms->sec0, 512);
  159 
  160         /*
  161          * Calculate MD5 from the first sector and use it for avoiding
  162          * recursive slices creation.
  163          */
  164         MD5Init(&md5sum);
  165         MD5Update(&md5sum, ms->sec0, sizeof(ms->sec0));
  166         MD5Final(ms->slicesum, &md5sum);
  167 
  168         return (0);
  169 }
  170 
  171 static int
  172 g_mbr_ioctl(struct g_provider *pp, u_long cmd, void *data, int fflag, struct thread *td)
  173 {
  174         struct g_geom *gp;
  175         struct g_mbr_softc *ms;
  176         struct g_slicer *gsp;
  177         struct g_consumer *cp;
  178         int error, opened;
  179 
  180         gp = pp->geom;
  181         gsp = gp->softc;
  182         ms = gsp->softc;
  183 
  184         opened = 0;
  185         error = 0;
  186         switch(cmd) {
  187         case DIOCSMBR: {
  188                 if (!(fflag & FWRITE))
  189                         return (EPERM);
  190                 DROP_GIANT();
  191                 g_topology_lock();
  192                 cp = LIST_FIRST(&gp->consumer);
  193                 if (cp->acw == 0) {
  194                         error = g_access(cp, 0, 1, 0);
  195                         if (error == 0)
  196                                 opened = 1;
  197                 }
  198                 if (!error)
  199                         error = g_mbr_modify(gp, ms, data, 512);
  200                 if (!error)
  201                         error = g_write_data(cp, 0, data, 512);
  202                 if (opened)
  203                         g_access(cp, 0, -1 , 0);
  204                 g_topology_unlock();
  205                 PICKUP_GIANT();
  206                 return(error);
  207         }
  208         default:
  209                 return (ENOIOCTL);
  210         }
  211 }
  212 
  213 static int
  214 g_mbr_start(struct bio *bp)
  215 {
  216         struct g_provider *pp;
  217         struct g_geom *gp;
  218         struct g_mbr_softc *mp;
  219         struct g_slicer *gsp;
  220         int idx;
  221 
  222         pp = bp->bio_to;
  223         idx = pp->index;
  224         gp = pp->geom;
  225         gsp = gp->softc;
  226         mp = gsp->softc;
  227         if (bp->bio_cmd == BIO_GETATTR) {
  228                 if (g_handleattr_int(bp, "MBR::type", mp->type[idx]))
  229                         return (1);
  230                 if (g_handleattr_off_t(bp, "MBR::offset",
  231                     gsp->slices[idx].offset))
  232                         return (1);
  233                 if (g_handleattr(bp, "MBR::slicesum", mp->slicesum,
  234                     sizeof(mp->slicesum)))
  235                         return (1);
  236         }
  237 
  238         return (0);
  239 }
  240 
  241 static void
  242 g_mbr_dumpconf(struct sbuf *sb, const char *indent, struct g_geom *gp, struct g_consumer *cp __unused, struct g_provider *pp)
  243 {
  244         struct g_mbr_softc *mp;
  245         struct g_slicer *gsp;
  246 
  247         gsp = gp->softc;
  248         mp = gsp->softc;
  249         g_slice_dumpconf(sb, indent, gp, cp, pp);
  250         if (pp != NULL) {
  251                 if (indent == NULL)
  252                         sbuf_printf(sb, " ty %d", mp->type[pp->index]);
  253                 else
  254                         sbuf_printf(sb, "%s<type>%d</type>\n", indent,
  255                             mp->type[pp->index]);
  256         }
  257 }
  258 
  259 static struct g_geom *
  260 g_mbr_taste(struct g_class *mp, struct g_provider *pp, int insist)
  261 {
  262         struct g_geom *gp;
  263         struct g_consumer *cp;
  264         int error;
  265         struct g_mbr_softc *ms;
  266         u_int fwsectors, sectorsize;
  267         u_char *buf;
  268         u_char hash[16];
  269         MD5_CTX md5sum;
  270 
  271         g_trace(G_T_TOPOLOGY, "mbr_taste(%s,%s)", mp->name, pp->name);
  272         g_topology_assert();
  273         if (!strcmp(pp->geom->class->name, MBR_CLASS_NAME))
  274                 return (NULL);
  275         gp = g_slice_new(mp, NDOSPART, pp, &cp, &ms, sizeof *ms, g_mbr_start);
  276         if (gp == NULL)
  277                 return (NULL);
  278         g_topology_unlock();
  279         do {
  280                 error = g_getattr("GEOM::fwsectors", cp, &fwsectors);
  281                 if (error)
  282                         fwsectors = 17;
  283                 sectorsize = cp->provider->sectorsize;
  284                 if (sectorsize < 512)
  285                         break;
  286                 ms->sectorsize = sectorsize;
  287                 buf = g_read_data(cp, 0, sectorsize, NULL);
  288                 if (buf == NULL)
  289                         break;
  290 
  291                 /*
  292                  * Calculate MD5 from the first sector and use it for avoiding
  293                  * recursive slices creation.
  294                  */
  295                 bcopy(buf, ms->sec0, 512);
  296                 MD5Init(&md5sum);
  297                 MD5Update(&md5sum, ms->sec0, sizeof(ms->sec0));
  298                 MD5Final(ms->slicesum, &md5sum);
  299 
  300                 error = g_getattr("MBR::slicesum", cp, &hash);
  301                 if (!error && !bcmp(ms->slicesum, hash, sizeof(hash))) {
  302                         g_free(buf);
  303                         break;
  304                 }
  305 
  306                 g_topology_lock();
  307                 g_mbr_modify(gp, ms, buf, 512);
  308                 g_topology_unlock();
  309                 g_free(buf);
  310                 break;
  311         } while (0);
  312         g_topology_lock();
  313         g_access(cp, -1, 0, 0);
  314         if (LIST_EMPTY(&gp->provider)) {
  315                 g_slice_spoiled(cp);
  316                 return (NULL);
  317         }
  318         return (gp);
  319 }
  320 
  321 static void
  322 g_mbr_config(struct gctl_req *req, struct g_class *mp, const char *verb)
  323 {
  324         struct g_geom *gp;
  325         struct g_consumer *cp;
  326         struct g_mbr_softc *ms;
  327         struct g_slicer *gsp;
  328         int opened = 0, error = 0;
  329         void *data;
  330         int len;
  331 
  332         g_topology_assert();
  333         gp = gctl_get_geom(req, mp, "geom");
  334         if (gp == NULL)
  335                 return;
  336         if (strcmp(verb, "write MBR")) {
  337                 gctl_error(req, "Unknown verb");
  338                 return;
  339         }
  340         gsp = gp->softc;
  341         ms = gsp->softc;
  342         data = gctl_get_param(req, "data", &len);
  343         if (data == NULL)
  344                 return;
  345         if (len < 512 || (len % 512)) {
  346                 gctl_error(req, "Wrong request length");
  347                 return;
  348         }
  349         cp = LIST_FIRST(&gp->consumer);
  350         if (cp->acw == 0) {
  351                 error = g_access(cp, 0, 1, 0);
  352                 if (error == 0)
  353                         opened = 1;
  354         }
  355         if (!error)
  356                 error = g_mbr_modify(gp, ms, data, len);
  357         if (error)
  358                 gctl_error(req, "conflict with open slices");
  359         if (!error)
  360                 error = g_write_data(cp, 0, data, len);
  361         if (error)
  362                 gctl_error(req, "sector zero write failed");
  363         if (opened)
  364                 g_access(cp, 0, -1 , 0);
  365         return;
  366 }
  367 
  368 static struct g_class g_mbr_class       = {
  369         .name = MBR_CLASS_NAME,
  370         .version = G_VERSION,
  371         .taste = g_mbr_taste,
  372         .dumpconf = g_mbr_dumpconf,
  373         .ctlreq = g_mbr_config,
  374         .ioctl = g_mbr_ioctl,
  375 };
  376 
  377 DECLARE_GEOM_CLASS(g_mbr_class, g_mbr);
  378 
  379 #define NDOSEXTPART             32
  380 struct g_mbrext_softc {
  381         int             type [NDOSEXTPART];
  382 };
  383 
  384 static int
  385 g_mbrext_start(struct bio *bp)
  386 {
  387         struct g_provider *pp;
  388         struct g_geom *gp;
  389         struct g_mbrext_softc *mp;
  390         struct g_slicer *gsp;
  391         int idx;
  392 
  393         pp = bp->bio_to;
  394         idx = pp->index;
  395         gp = pp->geom;
  396         gsp = gp->softc;
  397         mp = gsp->softc;
  398         if (bp->bio_cmd == BIO_GETATTR) {
  399                 if (g_handleattr_int(bp, "MBR::type", mp->type[idx]))
  400                         return (1);
  401         }
  402         return (0);
  403 }
  404 
  405 static void
  406 g_mbrext_dumpconf(struct sbuf *sb, const char *indent, struct g_geom *gp, struct g_consumer *cp __unused, struct g_provider *pp)
  407 {
  408         struct g_mbrext_softc *mp;
  409         struct g_slicer *gsp;
  410 
  411         g_slice_dumpconf(sb, indent, gp, cp, pp);
  412         gsp = gp->softc;
  413         mp = gsp->softc;
  414         if (pp != NULL) {
  415                 if (indent == NULL)
  416                         sbuf_printf(sb, " ty %d", mp->type[pp->index]);
  417                 else
  418                         sbuf_printf(sb, "%s<type>%d</type>\n", indent,
  419                             mp->type[pp->index]);
  420         }
  421 }
  422 
  423 static struct g_geom *
  424 g_mbrext_taste(struct g_class *mp, struct g_provider *pp, int insist __unused)
  425 {
  426         struct g_geom *gp;
  427         struct g_consumer *cp;
  428         int error, i, slice;
  429         struct g_mbrext_softc *ms;
  430         off_t off;
  431         u_char *buf;
  432         struct dos_partition dp[4];
  433         u_int fwsectors, sectorsize;
  434 
  435         g_trace(G_T_TOPOLOGY, "g_mbrext_taste(%s,%s)", mp->name, pp->name);
  436         g_topology_assert();
  437         if (strcmp(pp->geom->class->name, MBR_CLASS_NAME))
  438                 return (NULL);
  439         gp = g_slice_new(mp, NDOSEXTPART, pp, &cp, &ms, sizeof *ms,
  440             g_mbrext_start);
  441         if (gp == NULL)
  442                 return (NULL);
  443         g_topology_unlock();
  444         off = 0;
  445         slice = 0;
  446         do {
  447                 error = g_getattr("MBR::type", cp, &i);
  448                 if (error || (i != DOSPTYP_EXT && i != DOSPTYP_EXTLBA))
  449                         break;
  450                 error = g_getattr("GEOM::fwsectors", cp, &fwsectors);
  451                 if (error)
  452                         fwsectors = 17;
  453                 sectorsize = cp->provider->sectorsize;
  454                 if (sectorsize != 512)
  455                         break;
  456                 for (;;) {
  457                         buf = g_read_data(cp, off, sectorsize, NULL);
  458                         if (buf == NULL)
  459                                 break;
  460                         if (buf[0x1fe] != 0x55 && buf[0x1ff] != 0xaa) {
  461                                 g_free(buf);
  462                                 break;
  463                         }
  464                         for (i = 0; i < NDOSPART; i++) 
  465                                 dos_partition_dec(
  466                                     buf + DOSPARTOFF + 
  467                                     i * sizeof(struct dos_partition), dp + i);
  468                         g_free(buf);
  469                         if (0 && bootverbose) {
  470                                 printf("MBREXT Slice %d on %s:\n",
  471                                     slice + 5, gp->name);
  472                                 g_mbr_print(0, dp);
  473                                 g_mbr_print(1, dp + 1);
  474                         }
  475                         if ((dp[0].dp_flag & 0x7f) == 0 &&
  476                              dp[0].dp_size != 0 && dp[0].dp_typ != 0) {
  477                                 g_topology_lock();
  478                                 g_slice_config(gp, slice, G_SLICE_CONFIG_SET,
  479                                     (((off_t)dp[0].dp_start) << 9ULL) + off,
  480                                     ((off_t)dp[0].dp_size) << 9ULL,
  481                                     sectorsize,
  482                                     "%*.*s%d",
  483                                     strlen(gp->name) - 1,
  484                                     strlen(gp->name) - 1,
  485                                     gp->name,
  486                                     slice + 5);
  487                                 g_topology_unlock();
  488                                 ms->type[slice] = dp[0].dp_typ;
  489                                 slice++;
  490                         }
  491                         if (dp[1].dp_flag != 0)
  492                                 break;
  493                         if (dp[1].dp_typ != DOSPTYP_EXT &&
  494                             dp[1].dp_typ != DOSPTYP_EXTLBA)
  495                                 break;
  496                         if (dp[1].dp_size == 0)
  497                                 break;
  498                         off = ((off_t)dp[1].dp_start) << 9ULL;
  499                 }
  500                 break;
  501         } while (0);
  502         g_topology_lock();
  503         g_access(cp, -1, 0, 0);
  504         if (LIST_EMPTY(&gp->provider)) {
  505                 g_slice_spoiled(cp);
  506                 return (NULL);
  507         }
  508         return (gp);
  509 }
  510 
  511 
  512 static struct g_class g_mbrext_class    = {
  513         .name = MBREXT_CLASS_NAME,
  514         .version = G_VERSION,
  515         .taste = g_mbrext_taste,
  516         .dumpconf = g_mbrext_dumpconf,
  517 };
  518 
  519 DECLARE_GEOM_CLASS(g_mbrext_class, g_mbrext);

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