significantly simplified disklabel infrastructure. MBR handling becomes MI

to support hotplug media on most architectures.  disklabel setup and
verification done using new helper functions.  Disklabels must *always*
have a correct checksum now.  Same code paths are used to learn on-disk
location disklabels, to avoid new errors sneaking in.  Tested on almost all
cases, testing help from todd, kettenis, krw, otto, dlg, robert, gwk, drahn

2 files changed, 19 insertions, 314 deletions

diff --git a/sys/arch/amd64/amd64/disksubr.c b/sys/arch/amd64/amd64/disksubr.c
index 437f3674c2e..3dc92c8504f 100644
--- a/sys/arch/amd64/amd64/disksubr.c
+++ b/sys/arch/amd64/amd64/disksubr.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: disksubr.c,v 1.49 2007/06/14 03:37:23 deraadt Exp $	*/
+/*	$OpenBSD: disksubr.c,v 1.50 2007/06/17 00:27:28 deraadt Exp $	*/
 /*	$NetBSD: disksubr.c,v 1.21 1996/05/03 19:42:03 christos Exp $	*/
 
 /*
@@ -29,16 +29,12 @@
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
- *
- *	@(#)ufs_disksubr.c	7.16 (Berkeley) 5/4/91
  */
 
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/buf.h>
-#include <sys/device.h>
 #include <sys/disklabel.h>
-#include <sys/syslog.h>
 #include <sys/disk.h>
 #include <sys/reboot.h>
 #include <sys/conf.h>
@@ -69,37 +65,13 @@ char *
 readdisklabel(dev_t dev, void (*strat)(struct buf *),
     struct disklabel *lp, struct cpu_disklabel *osdep, int spoofonly)
 {
-	struct dos_partition dp[NDOSPART], *dp2;
-	struct partition *pp;
-	struct disklabel *dlp;
 	bios_diskinfo_t *pdi;
-	unsigned long extoff = 0;
-	unsigned int fattest;
 	struct buf *bp = NULL;
-	daddr64_t part_blkno = DOSBBSECTOR;
 	dev_t devno;
-	char *msg = NULL;
-	int dospartoff, cyl, i, ourpart = -1;
-	int wander = 1, n = 0, loop = 0;
+	char *msg;
 
-	/* minimal requirements for archetypal disk label */
-	if (lp->d_secsize < DEV_BSIZE)
-		lp->d_secsize = DEV_BSIZE;
-	if (DL_GETDSIZE(lp) == 0)
-		DL_SETDSIZE(lp, MAXDISKSIZE);
-	if (lp->d_secpercyl == 0) {
-		msg = "invalid geometry";
+	if ((msg = initdisklabel(lp)))
 		goto done;
-	}
-	lp->d_npartitions = RAW_PART + 1;
-	for (i = 0; i < RAW_PART; i++) {
-		DL_SETPSIZE(&lp->d_partitions[i], 0);
-		DL_SETPOFFSET(&lp->d_partitions[i], 0);
-	}
-	if (DL_GETPSIZE(&lp->d_partitions[RAW_PART]) == 0)
-		DL_SETPSIZE(&lp->d_partitions[RAW_PART], DL_GETDSIZE(lp));
-	DL_SETPOFFSET(&lp->d_partitions[RAW_PART], 0);
-	lp->d_version = 1;
 
 	/* Look for any BIOS geometry information we should honour. */
 	devno = chrtoblk(dev);
@@ -124,193 +96,21 @@ readdisklabel(dev_t dev, void (*strat)(struct buf *),
 	bp = geteblk((int)lp->d_secsize);
 	bp->b_dev = dev;
 
-	/* do dos partitions in the process of getting disklabel? */
-	dospartoff = 0;
-	cyl = LABELSECTOR / lp->d_secpercyl;
-
-	/*
-	 * Read dos partition table, follow extended partitions.
-	 * Map the partitions to disklabel entries i-p
-	 */
-	while (wander && n < 8 && loop < 8) {
-		loop++;
-		wander = 0;
-		if (part_blkno < extoff)
-			part_blkno = extoff;
-
-		/* read boot record */
-		bp->b_blkno = part_blkno;
-		bp->b_bcount = lp->d_secsize;
-		bp->b_flags = B_BUSY | B_READ;
-		bp->b_cylinder = part_blkno / lp->d_secpercyl;
-		(*strat)(bp);
-
-		/* if successful, wander through dos partition table */
-		if (biowait(bp)) {
-			msg = "dos partition I/O error";
-			goto done;
-		}
-		bcopy(bp->b_data + DOSPARTOFF, dp, sizeof(dp));
-
-		if (ourpart == -1 && part_blkno == DOSBBSECTOR) {
-			/* Search for our MBR partition */
-			for (dp2=dp, i=0; i < NDOSPART && ourpart == -1;
-			    i++, dp2++)
-				if (letoh32(dp2->dp_size) &&
-				    dp2->dp_typ == DOSPTYP_OPENBSD)
-					ourpart = i;
-			if (ourpart == -1)
-				goto donot;
-			/*
-			 * This is our MBR partition. need sector address
-			 * for SCSI/IDE, cylinder for ESDI/ST506/RLL
-			 */
-			dp2 = &dp[ourpart];
-			dospartoff = letoh32(dp2->dp_start) + part_blkno;
-			cyl = DPCYL(dp2->dp_scyl, dp2->dp_ssect);
-
-			/* XXX build a temporary disklabel */
-			DL_SETPSIZE(&lp->d_partitions[0], letoh32(dp2->dp_size));
-			DL_SETPOFFSET(&lp->d_partitions[0],
-			    letoh32(dp2->dp_start) + part_blkno);
-			if (lp->d_ntracks == 0)
-				lp->d_ntracks = dp2->dp_ehd + 1;
-			if (lp->d_nsectors == 0)
-				lp->d_nsectors = DPSECT(dp2->dp_esect);
-			if (lp->d_secpercyl == 0)
-				lp->d_secpercyl = lp->d_ntracks *
-				    lp->d_nsectors;
-		}
-donot:
-		/*
-		 * In case the disklabel read below fails, we want to
-		 * provide a fake label in i-p.
-		 */
-		for (dp2=dp, i=0; i < NDOSPART && n < 8; i++, dp2++) {
-			pp = &lp->d_partitions[8+n];
-
-			if (dp2->dp_typ == DOSPTYP_OPENBSD)
-				continue;
-			if (letoh32(dp2->dp_size) > DL_GETDSIZE(lp))
-				continue;
-			if (letoh32(dp2->dp_start) > DL_GETDSIZE(lp))
-				continue;
-			if (letoh32(dp2->dp_size) == 0)
-				continue;
-			if (letoh32(dp2->dp_start))
-				DL_SETPOFFSET(pp,
-				    letoh32(dp2->dp_start) + part_blkno);
-
-			DL_SETPSIZE(pp, letoh32(dp2->dp_size));
-
-			switch (dp2->dp_typ) {
-			case DOSPTYP_UNUSED:
-				pp->p_fstype = FS_UNUSED;
-				n++;
-				break;
-
-			case DOSPTYP_LINUX:
-				pp->p_fstype = FS_EXT2FS;
-				n++;
-				break;
-
-			case DOSPTYP_FAT12:
-			case DOSPTYP_FAT16S:
-			case DOSPTYP_FAT16B:
-			case DOSPTYP_FAT16L:
-			case DOSPTYP_FAT32:
-			case DOSPTYP_FAT32L:
-				pp->p_fstype = FS_MSDOS;
-				n++;
-				break;
-			case DOSPTYP_EXTEND:
-			case DOSPTYP_EXTENDL:
-				part_blkno = letoh32(dp2->dp_start) + extoff;
-				if (!extoff) {
-					extoff = letoh32(dp2->dp_start);
-					part_blkno = 0;
-				}
-				wander = 1;
-				break;
-			default:
-				pp->p_fstype = FS_OTHER;
-				n++;
-				break;
-			}
-		}
-	}
-	lp->d_bbsize = 8192;
-	lp->d_sbsize = 64*1024;		/* XXX ? */
-	lp->d_npartitions = MAXPARTITIONS;
-
-	if (n == 0 && part_blkno == DOSBBSECTOR) {
-		/* Check for a short jump instruction. */
-		fattest = ((bp->b_data[0] << 8) & 0xff00) | (bp->b_data[2] &
-		    0xff);
-		if (fattest != 0xeb90 && fattest != 0xe900)
-			goto notfat;
-
-		/* Check for a valid bytes per sector value. */
-		fattest = ((bp->b_data[12] << 8) & 0xff00) | (bp->b_data[11] &
-		    0xff);
-		if (fattest < 512 || fattest > 4096 || (fattest % 512 != 0))
-			goto notfat;
-
-		/* Check the end of sector marker. */
-		fattest = ((bp->b_data[510] << 8) & 0xff00) | (bp->b_data[511] &
-		    0xff);
-		if (fattest != 0x55aa)
-			goto notfat;
-
-		/* Looks like a FAT filesystem. Spoof 'i'. */
-		DL_SETPSIZE(&lp->d_partitions['i' - 'a'],
-		    DL_GETPSIZE(&lp->d_partitions[RAW_PART]));
-		DL_SETPOFFSET(&lp->d_partitions['i' - 'a'], 0);
-		lp->d_partitions['i' - 'a'].p_fstype = FS_MSDOS;
-	}
-notfat:
-
-	/* don't read the on-disk label if we are in spoofed-only mode */
-	if (spoofonly)
-		goto done;
-
-	/* next, dig out disk label */
-	bp->b_blkno = dospartoff + LABELSECTOR;
-	bp->b_cylinder = cyl;
-	bp->b_bcount = lp->d_secsize;
-	bp->b_flags = B_BUSY | B_READ;
-	(*strat)(bp);
-
-	/* if successful, locate disk label within block and validate */
-	if (biowait(bp)) {
-		/* XXX we return the faked label built so far */
-		msg = "disk label I/O error";
+	msg = readdoslabel(bp, strat, lp, osdep, NULL, NULL, spoofonly);
+	if (msg == NULL)
 		goto done;
-	}
-	for (dlp = (struct disklabel *)bp->b_data;
-	    dlp <= (struct disklabel *)(bp->b_data + lp->d_secsize - sizeof(*dlp));
-	    dlp = (struct disklabel *)((char *)dlp + sizeof(long))) {
-		if (dlp->d_magic != DISKMAGIC || dlp->d_magic2 != DISKMAGIC) {
-			if (msg == NULL)
-				msg = "no disk label";
-		} else if (dlp->d_npartitions > MAXPARTITIONS ||
-			   dkcksum(dlp) != 0)
-			msg = "disk label corrupted";
-		else {
-			DL_SETDSIZE(dlp, DL_GETDSIZE(lp));
-			*lp = *dlp;
-			msg = NULL;
-			break;
-		}
-	}
 
 #if defined(CD9660)
-	if (msg && iso_disklabelspoof(dev, strat, lp) == 0)
+	if (iso_disklabelspoof(dev, strat, lp) == 0) {
 		msg = NULL;
+		goto done;
+	}
 #endif
 #if defined(UDF)
-	if (msg && udf_disklabelspoof(dev, strat, lp) == 0)
+	if (udf_disklabelspoof(dev, strat, lp) == 0) {
 		msg = NULL;
+		goto done;
+	}
 #endif
 
 done:
@@ -318,7 +118,6 @@ done:
 		bp->b_flags |= B_INVAL;
 		brelse(bp);
 	}
-	disklabeltokernlabel(lp);
 	return (msg);
 }
 
@@ -330,73 +129,30 @@ int
 writedisklabel(dev_t dev, void (*strat)(struct buf *),
     struct disklabel *lp, struct cpu_disklabel *osdep)
 {
-	struct dos_partition dp[NDOSPART], *dp2;
+	int error, partoff = -1, cyl = 0;
 	struct disklabel *dlp;
 	struct buf *bp = NULL;
-	int error, dospartoff, cyl, i;
-	int ourpart = -1;
 
 	/* get a buffer and initialize it */
 	bp = geteblk((int)lp->d_secsize);
 	bp->b_dev = dev;
 
-	/* do dos partitions in the process of getting disklabel? */
-	dospartoff = 0;
-	cyl = LABELSECTOR / lp->d_secpercyl;
-
-	/* read master boot record */
-	bp->b_blkno = DOSBBSECTOR;
-	bp->b_bcount = lp->d_secsize;
-	bp->b_flags = B_BUSY | B_READ;
-	bp->b_cylinder = DOSBBSECTOR / lp->d_secpercyl;
-	(*strat)(bp);
-
-	if ((error = biowait(bp)) != 0)
+	if (readdoslabel(bp, strat, lp, osdep, &partoff, &cyl, 1) != NULL) {
+		error = EIO;
 		goto done;
-
-	/* XXX how do we check veracity/bounds of this? */
-	bcopy(bp->b_data + DOSPARTOFF, dp, sizeof(dp));
-
-	for (dp2=dp, i=0; i < NDOSPART && ourpart == -1; i++, dp2++)
-		if (letoh32(dp2->dp_size) && dp2->dp_typ == DOSPTYP_OPENBSD)
-			ourpart = i;
-
-	if (ourpart != -1) {
-		dp2 = &dp[ourpart];
-
-		/*
-		 * need sector address for SCSI/IDE,
-		 * cylinder for ESDI/ST506/RLL
-		 */
-		dospartoff = letoh32(dp2->dp_start);
-		cyl = DPCYL(dp2->dp_scyl, dp2->dp_ssect);
 	}
 
-	/* next, dig out disk label */
-	bp->b_blkno = dospartoff + LABELSECTOR;
+	/* Read it in, slap the new label in, and write it back out */
+	bp->b_blkno = partoff + LABELSECTOR;
 	bp->b_cylinder = cyl;
 	bp->b_bcount = lp->d_secsize;
 	bp->b_flags = B_BUSY | B_READ;
 	(*strat)(bp);
-
-	/* if successful, locate disk label within block and validate */
 	if ((error = biowait(bp)) != 0)
 		goto done;
-	for (dlp = (struct disklabel *)bp->b_data;
-	    dlp <= (struct disklabel *)(bp->b_data + lp->d_secsize - sizeof(*dlp));
-	    dlp = (struct disklabel *)((char *)dlp + sizeof(long))) {
-		if (dlp->d_magic == DISKMAGIC && dlp->d_magic2 == DISKMAGIC &&
-		    dkcksum(dlp) == 0) {
-			*dlp = *lp;
-			bp->b_flags = B_BUSY | B_WRITE;
-			(*strat)(bp);
-			error = biowait(bp);
-			goto done;
-		}
-	}
 
-	/* Write it in the regular place. */
-	*(struct disklabel *)bp->b_data = *lp;
+	dlp = (struct disklabel *)(bp->b_data + LABELOFFSET);
+	*dlp = *lp;
 	bp->b_flags = B_BUSY | B_WRITE;
 	(*strat)(bp);
 	error = biowait(bp);
diff --git a/sys/arch/amd64/include/disklabel.h b/sys/arch/amd64/include/disklabel.h
index 0851f8a57b9..12c78faa294 100644
--- a/sys/arch/amd64/include/disklabel.h
+++ b/sys/arch/amd64/include/disklabel.h
@@ -1,5 +1,4 @@
-/*	$OpenBSD: disklabel.h,v 1.8 2006/10/20 23:47:42 krw Exp $	*/
-/*	$NetBSD: disklabel.h,v 1.3 1996/03/09 20:52:54 ghudson Exp $	*/
+/*	$OpenBSD: disklabel.h,v 1.9 2007/06/17 00:27:26 deraadt Exp $	*/
 
 /*
  * Copyright (c) 1994 Christopher G. Demetriou
@@ -37,58 +36,8 @@
 #define	LABELSECTOR	1		/* sector containing label */
 #define	LABELOFFSET	0		/* offset of label in sector */
 #define	MAXPARTITIONS	16		/* number of partitions */
-#define	RAW_PART	2		/* raw partition: ie. rsd0c */
-
-/* DOS partition table -- located in boot block */
-#define	DOSBBSECTOR	0		/* DOS boot block relative sector # */
-#define	DOSPARTOFF	446
-#define	DOSDISKOFF	444
-#define	NDOSPART	4
-#define	DOSACTIVE	0x80		/* active partition */
-
-struct dos_partition {
-	u_int8_t	dp_flag;	/* bootstrap flags */
-	u_int8_t	dp_shd;		/* starting head */
-	u_int8_t	dp_ssect;	/* starting sector */
-	u_int8_t	dp_scyl;	/* starting cylinder */
-	u_int8_t	dp_typ;		/* partition type (see below) */
-	u_int8_t	dp_ehd;		/* end head */
-	u_int8_t	dp_esect;	/* end sector */
-	u_int8_t	dp_ecyl;	/* end cylinder */
-	u_int32_t	dp_start;	/* absolute starting sector number */
-	u_int32_t	dp_size;	/* partition size in sectors */
-};
-
-/* Known DOS partition types. */
-#define	DOSPTYP_UNUSED	0x00		/* Unused partition */
-#define DOSPTYP_FAT12	0x01		/* 12-bit FAT */
-#define DOSPTYP_FAT16S	0x04		/* 16-bit FAT, less than 32M */
-#define DOSPTYP_EXTEND	0x05		/* Extended; contains sub-partitions */
-#define DOSPTYP_FAT16B	0x06		/* 16-bit FAT, more than 32M */
-#define DOSPTYP_FAT32	0x0b		/* 32-bit FAT */
-#define DOSPTYP_FAT32L	0x0c		/* 32-bit FAT, LBA-mapped */
-#define DOSPTYP_FAT16L	0x0e		/* 16-bit FAT, LBA-mapped */
-#define DOSPTYP_EXTENDL 0x0f		/* Extended, LBA-mapped; contains sub-partitions */
-#define DOSPTYP_ONTRACK	0x54
-#define	DOSPTYP_LINUX	0x83		/* That other thing */
-#define DOSPTYP_FREEBSD	0xa5		/* FreeBSD partition type */
-#define DOSPTYP_OPENBSD	0xa6		/* OpenBSD partition type */
-#define DOSPTYP_NETBSD	0xa9		/* NetBSD partition type */
-
-struct dos_mbr {
-	u_int8_t		dmbr_boot[DOSPARTOFF];
-	struct dos_partition	dmbr_parts[NDOSPART];
-	u_int16_t		dmbr_sign;
-} __packed;
-
-#define DOSMBR_SIGNATURE	(0xaa55)
-#define DOSMBR_SIGNATURE_OFF	(0x1fe)
 
 struct cpu_disklabel {
 };
 
-/* Isolate the relevant bits to get sector and cylinder. */
-#define	DPSECT(s)	((s) & 0x3f)
-#define	DPCYL(c, s)	((c) + (((s) & 0xc0) << 2))
-
 #endif /* _MACHINE_DISKLABEL_H_ */