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Use the hotspot code to prevent people from overwriting their disklabel

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with stuff which would ruin the day for any open parititons.

Approved by:	re
This commit is contained in:
Poul-Henning Kamp 2002-12-02 20:23:54 +00:00
parent 7e8dbd8b20
commit 00e11500e2
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=107526
1 changed files with 90 additions and 11 deletions
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101
sys/geom/geom_bsd.c
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@ -198,6 +198,12 @@ g_bsd_leenc_disklabel(u_char *ptr, struct disklabel *d)
g_bsd_leenc_partition(ptr + 148 + 16 * i, &d->d_partitions[i]);
}
static int
g_bsd_ondisk_size(void)
{
return (148 + 16 * MAXPARTITIONS);
}
/*
* For reasons which were valid and just in their days, FreeBSD/i386 uses
* absolute disk-addresses in disklabels. The way it works is that the
@ -418,7 +424,7 @@ g_bsd_lesum(struct disklabel *dl, u_char *p)
*/
static int
g_bsd_try(struct g_slicer *gsp, struct g_consumer *cp, int secsize, struct g_bsd_softc *ms, off_t offset)
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)
{
int error;
u_char *buf;
@ -456,6 +462,9 @@ g_bsd_try(struct g_slicer *gsp, struct g_consumer *cp, int secsize, struct g_bsd
if (error == 0) {
gsp->frontstuff = 16 * secsize; /* XXX */
ms->labeloffset = offset;
g_topology_lock();
g_slice_conf_hot(gp, 0, offset, g_bsd_ondisk_size());
g_topology_unlock();
}
return (error);
}
@ -535,6 +544,52 @@ g_bsd_ioctl(void *arg)
g_io_deliver(bp, error);
}
/*
* If the user tries to overwrite our disklabel through an open partition
* or via a magicwrite config call, we end up here and try to prevent
* footshooting as best we can.
*/
static void
g_bsd_hotwrite(void *arg)
{
struct bio *bp;
struct g_geom *gp;
struct g_slicer *gsp;
struct g_bsd_softc *ms;
struct g_bsd_softc fake;
u_char *p;
int error;
bp = arg;
gp = bp->bio_to->geom;
gsp = gp->softc;
ms = gsp->softc;
p = bp->bio_data + ms->labeloffset - bp->bio_offset;
g_bsd_ledec_disklabel(p, &fake.ondisk);
ondisk2inram(&fake);
if (g_bsd_checklabel(&fake.inram)) {
g_io_deliver(bp, EPERM);
return;
}
if (g_bsd_lesum(&fake.ondisk, p) != 0) {
g_io_deliver(bp, EPERM);
return;
}
g_topology_unlock();
error = g_bsd_modify(gp, &fake.inram); /* May pick up topology. */
if (error) {
g_io_deliver(bp, EPERM);
g_topology_lock();
return;
}
/* Update our copy of the disklabel. */
ms->inram = fake.inram;
inram2ondisk(ms);
g_bsd_leenc_disklabel(p, &ms->ondisk);
g_slice_finish_hot(bp);
}
/*-
* This start routine is only called for non-trivial requests, all the
* trivial ones are handled autonomously by the slice code.
@ -558,6 +613,23 @@ g_bsd_start(struct bio *bp)
gp = bp->bio_to->geom;
gsp = gp->softc;
ms = gsp->softc;
switch(bp->bio_cmd) {
case BIO_READ:
/* We allow reading of our hot spots */
return (0);
case BIO_DELETE:
/* We do not allow deleting our hot spots */
return (EPERM);
case BIO_WRITE:
g_call_me(g_bsd_hotwrite, bp);
return (EJUSTRETURN);
case BIO_GETATTR:
case BIO_SETATTR:
break;
default:
KASSERT(0 == 1, ("Unknown bio_cmd in g_bsd_start (%d)",
bp->bio_cmd));
}
/* We only handle ioctl(2) requests of the right format. */
if (strcmp(bp->bio_attribute, "GEOM::ioctl"))
@ -707,16 +779,23 @@ g_bsd_taste(struct g_class *mp, struct g_provider *pp, int flags)
* attach to any other type (BSD was handles above)
*/
error = g_getattr("MBR::type", cp, &i);
if (!error && i != 165 && flags == G_TF_NORMAL)
break;
if (!error) {
if (i != 165 && flags == G_TF_NORMAL)
break;
error = g_getattr("MBR::offset", cp, &ms->mbroffset);
if (error)
break;
}
/* Same thing if we are inside a PC98 */
error = g_getattr("PC98::type", cp, &i);
if (!error && i != 0xc494 && flags == G_TF_NORMAL)
break;
ms->mbroffset = 0;
g_getattr("MBR::offset", cp, &ms->mbroffset);
g_getattr("PC98::offset", cp, &ms->mbroffset);
if (!error) {
if (i != 0xc494 && flags == G_TF_NORMAL)
break;
error = g_getattr("PC98::offset", cp, &ms->mbroffset);
if (error)
break;
}
/* Get sector size, we need it to read data. */
secsize = cp->provider->sectorsize;
@ -724,11 +803,11 @@ g_bsd_taste(struct g_class *mp, struct g_provider *pp, int flags)
break;
/* First look for a label at the start of the second sector. */
error = g_bsd_try(gsp, cp, secsize, ms, secsize);
error = g_bsd_try(gp, gsp, cp, secsize, ms, secsize);
/* Next, look for alpha labels */
if (error)
error = g_bsd_try(gsp, cp, secsize, ms,
error = g_bsd_try(gp, gsp, cp, secsize, ms,
ALPHA_LABEL_OFFSET);
/* If we didn't find a label, punt. */