Make fsck_msdos work with non-512-byte sector devices. Problem noted

by and fixes tested by Alexey Vatchenko.

Add a bunch of tests and error messages so whatever media/devices
this breaks will be more easily fixed.

Ignore invalid signatures since we have other checks and many media
have missing signatures.

Use character device to read disk even when called directly.

4 files changed, 128 insertions, 58 deletions

diff --git a/sbin/fsck_msdos/boot.c b/sbin/fsck_msdos/boot.c
index 8c57fc167aa..8a7f54fcabe 100644
--- a/sbin/fsck_msdos/boot.c
+++ b/sbin/fsck_msdos/boot.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: boot.c,v 1.15 2010/12/18 04:57:34 deraadt Exp $	*/
+/*	$OpenBSD: boot.c,v 1.16 2012/03/31 17:53:34 krw Exp $	*/
 /*	$NetBSD: boot.c,v 1.5 1997/10/17 11:19:23 ws Exp $	*/
 
 /*
@@ -33,6 +33,9 @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+#include <sys/param.h>
+#include <sys/disklabel.h>
+
 #include <stdlib.h>
 #include <string.h>
 #include <ctype.h>
@@ -44,21 +47,42 @@
 int
 readboot(int dosfs, struct bootblock *boot)
 {
-	u_char block[DOSBOOTBLOCKSIZE];
-	u_char fsinfo[2 * DOSBOOTBLOCKSIZE];
-	u_char backup[DOSBOOTBLOCKSIZE];
-	int ret = FSOK;
+	u_char *block;
+	u_char *fsinfo;
+	u_char *backup;
+	int ret = FSOK, secsize = lab.d_secsize, fsinfosz;
 	off_t o;
 	ssize_t n;
 
-	if ((n = read(dosfs, block, sizeof block)) == -1 || n != sizeof block) {
+	if (secsize < DOSBOOTBLOCKSIZE) {
+		xperror("sector size < DOSBOOTBLOCKSIZE");
+		return (FSFATAL);
+	}
+	if (DOSBOOTBLOCKSIZE != DEV_BSIZE) {
+		xperror("DOSBOOTBLOCKSIZE != DEV_BSIZE");
+		return (FSFATAL);
+	}
+
+	block = malloc(secsize);
+	if (block == NULL) {
+		xperror("could not malloc boot block");
+		return FSFATAL;
+	}
+
+	if ((o = lseek(dosfs, 0, SEEK_SET)) == -1) {
+		xperror("could not seek boot block");
+		return FSFATAL;
+	}
+
+	n = read(dosfs, block, secsize);
+	if (n == -1 || n != secsize) {
 		xperror("could not read boot block");
 		return (FSFATAL);
 	}
 
 	if (block[510] != 0x55 || block[511] != 0xaa) {
-		pfatal("Invalid signature in boot block: %02x%02x\n", block[511], block[510]);
-		return FSFATAL;
+		pfatal("Invalid signature in boot block: %02x%02x\n",
+		    block[511], block[510]);
 	}
 
 	memset(boot, 0, sizeof *boot);
@@ -66,7 +90,15 @@ readboot(int dosfs, struct bootblock *boot)
 
 	/* decode bios parameter block */
 	boot->BytesPerSec = block[11] + (block[12] << 8);
+	if (boot->BytesPerSec == 0 || boot->BytesPerSec != secsize) {
+		pfatal("Invalid sector size: %u\n", boot->BytesPerSec);
+		return (FSFATAL);
+	}
 	boot->SecPerClust = block[13];
+	if (boot->SecPerClust == 0) {
+		pfatal("Invalid cluster size: %u\n", boot->SecPerClust);
+		return (FSFATAL);
+	}
 	boot->ResSectors = block[14] + (block[15] << 8);
 	boot->FATs = block[16];
 	boot->RootDirEnts = block[17] + (block[18] << 8);
@@ -80,9 +112,8 @@ readboot(int dosfs, struct bootblock *boot)
 
 	boot->FATsecs = boot->FATsmall;
 
-	if (!boot->RootDirEnts)
+	if (!boot->RootDirEnts) {
 		boot->flags |= FAT32;
-	if (boot->flags & FAT32) {
 		boot->FATsecs = block[36] + (block[37] << 8)
 				+ (block[38] << 16) + (block[39] << 24);
 		if (block[40] & 0x80)
@@ -100,14 +131,27 @@ readboot(int dosfs, struct bootblock *boot)
 		boot->FSInfo = block[48] + (block[49] << 8);
 		boot->Backup = block[50] + (block[51] << 8);
 
-		o = boot->FSInfo * boot->BytesPerSec;
-		if ((o = lseek(dosfs, o, SEEK_SET)) == -1
-		    || o != boot->FSInfo * boot->BytesPerSec
-		    || (n = read(dosfs, fsinfo, sizeof fsinfo)) == -1
-		    || n != sizeof fsinfo) {
+		o = lseek(dosfs, boot->FSInfo * secsize, SEEK_SET);
+		if (o == -1 || o != boot->FSInfo * secsize) {
+			xperror("could not seek fsinfo block");
+			return FSFATAL;
+		}
+
+		if ((2 * DOSBOOTBLOCKSIZE) < secsize)
+			fsinfosz = secsize;
+		else
+			fsinfosz = 2 * secsize;
+		fsinfo = malloc(fsinfosz);
+		if (fsinfo == NULL) {
+			xperror("could not malloc fsinfo");
+			return FSFATAL;
+		}
+		n = read(dosfs, fsinfo, fsinfosz);
+		if (n == -1 || n != fsinfosz) {
 			xperror("could not read fsinfo block");
 			return FSFATAL;
 		}
+
 		if (memcmp(fsinfo, "RRaA", 4)
 		    || memcmp(fsinfo + 0x1e4, "rrAa", 4)
 		    || fsinfo[0x1fc]
@@ -129,11 +173,14 @@ readboot(int dosfs, struct bootblock *boot)
 				fsinfo[0x3fe] = 0x55;
 				fsinfo[0x3ff] = 0xaa;
 
-				o = boot->FSInfo * boot->BytesPerSec;
-				if ((o = lseek(dosfs, o, SEEK_SET)) == -1
-				    || o != boot->FSInfo * boot->BytesPerSec
-				    || (n = write(dosfs, fsinfo, sizeof fsinfo)) == -1
-				    || n != sizeof fsinfo) {
+				o = lseek(dosfs, boot->FSInfo * secsize,
+				    SEEK_SET);
+				if (o == -1 || o != boot->FSInfo * secsize) {
+					xperror("Unable to seek FSInfo");
+					return FSFATAL;
+				}
+				n = write(dosfs, block, fsinfosz);
+				if (n == -1 || n != fsinfosz) {
 					xperror("Unable to write FSInfo");
 					return FSFATAL;
 				}
@@ -150,11 +197,18 @@ readboot(int dosfs, struct bootblock *boot)
 				       + (fsinfo[0x1ef] << 24);
 		}
 
-		o = boot->Backup * boot->BytesPerSec;
-		if ((o = lseek(dosfs, o, SEEK_SET)) == -1
-		    || o != boot->Backup * boot->BytesPerSec
-		    || (n = read(dosfs, backup, sizeof backup)) == -1
-		    || n != sizeof backup) {
+		o = lseek(dosfs, boot->Backup * secsize, SEEK_SET);
+		if (o == -1 || o != boot->Backup * secsize) {
+			xperror("could not seek backup bootblock");
+			return (FSFATAL);
+		}
+		backup = malloc(2 * secsize); /* In case we check fsinfo. */
+		if (backup == NULL) {
+			xperror("could not malloc backup boot block");
+			return FSFATAL;
+		}
+		n = read(dosfs, backup, secsize);
+		if (n == -1 || n != secsize) {
 			xperror("could not read backup bootblock");
 			return FSFATAL;
 		}
@@ -172,7 +226,6 @@ readboot(int dosfs, struct bootblock *boot)
 		 */
 		if (backup[510] != 0x55 || backup[511] != 0xaa) {
 			pfatal("Invalid signature in backup boot block: %02x%02x\n", backup[511], backup[510]);
-			return FSFATAL;
 		}
 		if (memcmp(block + 11, backup + 11, 79)) {
 			pfatal("backup doesn't compare to primary bootblock\n");
@@ -181,18 +234,8 @@ readboot(int dosfs, struct bootblock *boot)
 		/* Check backup FSInfo?					XXX */
 	}
 
-	if (boot->BytesPerSec == 0 || boot->BytesPerSec % DOSBOOTBLOCKSIZE
-	    != 0) {
-		pfatal("Invalid sector size: %u\n", boot->BytesPerSec);
-		return (FSFATAL);
-	}
-	if (boot->SecPerClust == 0) {
-		pfatal("Invalid cluster size: %u\n", boot->SecPerClust);
-		return (FSFATAL);
-	}
-
-	boot->ClusterOffset = (boot->RootDirEnts * 32 + boot->BytesPerSec - 1)
-	    / boot->BytesPerSec
+	boot->ClusterOffset = (boot->RootDirEnts * 32 + secsize - 1)
+	    / secsize
 	    + boot->ResSectors
 	    + boot->FATs * boot->FATsecs
 	    - CLUST_FIRST * boot->SecPerClust;
@@ -218,13 +261,13 @@ readboot(int dosfs, struct bootblock *boot)
 
 	switch (boot->ClustMask) {
 	case CLUST32_MASK:
-		boot->NumFatEntries = (boot->FATsecs * boot->BytesPerSec) / 4;
+		boot->NumFatEntries = (boot->FATsecs * secsize) / 4;
 		break;
 	case CLUST16_MASK:
-		boot->NumFatEntries = (boot->FATsecs * boot->BytesPerSec) / 2;
+		boot->NumFatEntries = (boot->FATsecs * secsize) / 2;
 		break;
 	default:
-		boot->NumFatEntries = (boot->FATsecs * boot->BytesPerSec * 2) / 3;
+		boot->NumFatEntries = (boot->FATsecs * secsize * 2) / 3;
 		break;
 	}
 
@@ -233,7 +276,7 @@ readboot(int dosfs, struct bootblock *boot)
 		       boot->NumClusters, boot->FATsecs);
 		return (FSFATAL);
 	}
-	boot->ClusterSize = boot->BytesPerSec * boot->SecPerClust;
+	boot->ClusterSize = boot->SecPerClust * secsize;
 
 	boot->NumFiles = 1;
 	boot->NumFree = 0;
@@ -244,18 +287,34 @@ readboot(int dosfs, struct bootblock *boot)
 int
 writefsinfo(int dosfs, struct bootblock *boot)
 {
-	u_char fsinfo[2 * DOSBOOTBLOCKSIZE];
+	u_char *fsinfo;
+	int secsize = lab.d_secsize, fsinfosz;
 	off_t o;
 	ssize_t n;
 
-	o = boot->FSInfo * boot->BytesPerSec;
-	if ((o = lseek(dosfs, o, SEEK_SET)) == -1
-	   || o != boot->FSInfo * boot->BytesPerSec
-	   || (n = read(dosfs, fsinfo, sizeof fsinfo)) == -1
-	   || n != sizeof fsinfo) {
+	if ((2 * DOSBOOTBLOCKSIZE) < secsize)
+		fsinfosz = secsize;
+	else
+		fsinfosz = 2 * secsize;
+
+	fsinfo = malloc(fsinfosz);
+	if (fsinfo == NULL) {
+		xperror("could not malloc fsinfo block");
+		return FSFATAL;
+	}
+
+	o = lseek(dosfs, boot->FSInfo * secsize, SEEK_SET);
+	if (o == -1 || o != boot->FSInfo * secsize) {
+		xperror("could not seek fsinfo block");
+		return FSFATAL;
+	}
+
+	n = read(dosfs, fsinfo, fsinfosz);
+	if (n == -1 || n != fsinfosz) {
 		xperror("could not read fsinfo block");
 		return FSFATAL;
 	}
+
 	fsinfo[0x1e8] = (u_char)boot->FSFree;
 	fsinfo[0x1e9] = (u_char)(boot->FSFree >> 8);
 	fsinfo[0x1ea] = (u_char)(boot->FSFree >> 16);
@@ -265,14 +324,17 @@ writefsinfo(int dosfs, struct bootblock *boot)
 	fsinfo[0x1ee] = (u_char)(boot->FSNext >> 16);
 	fsinfo[0x1ef] = (u_char)(boot->FSNext >> 24);
 
-	o = boot->FSInfo * boot->BytesPerSec;
-	if ((o = lseek(dosfs, o, SEEK_SET)) == -1
-	    || o != boot->FSInfo * boot->BytesPerSec
-	    || (n = write(dosfs, fsinfo, sizeof fsinfo)) == -1
-	    || n != sizeof fsinfo) {
+	o = lseek(dosfs, o, SEEK_SET);
+	if (o == -1 || o != boot->FSInfo * boot->BytesPerSec) {
+		xperror("Unable to seek FSInfo");
+		return FSFATAL;
+	}
+	n = write(dosfs, fsinfo, fsinfosz);
+	if (n == -1 || n != fsinfosz) {
 		xperror("Unable to write FSInfo");
 		return FSFATAL;
 	}
+
 	/*
 	 * Technically, we should return FSBOOTMOD here.
 	 *
diff --git a/sbin/fsck_msdos/check.c b/sbin/fsck_msdos/check.c
index ee6a05b4596..26f2afce48f 100644
--- a/sbin/fsck_msdos/check.c
+++ b/sbin/fsck_msdos/check.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: check.c,v 1.14 2010/12/17 19:36:03 millert Exp $	*/
+/*	$OpenBSD: check.c,v 1.15 2012/03/31 17:53:34 krw Exp $	*/
 /*	$NetBSD: check.c,v 1.8 1997/10/17 11:19:29 ws Exp $	*/
 
 /*
@@ -34,6 +34,9 @@
  */
 
 #include <sys/param.h>
+#include <sys/ioctl.h>
+#include <sys/dkio.h>
+#include <sys/disklabel.h>
 #include <stdlib.h>
 #include <string.h>
 #include <ctype.h>
@@ -44,6 +47,8 @@
 
 #include "ext.h"
 
+struct disklabel lab;
+
 int
 checkfilesys(const char *fname)
 {
@@ -75,6 +80,9 @@ checkfilesys(const char *fname)
 		printf("\n");
 	}
 
+	if (ioctl(dosfs, DIOCGDINFO, (char *)&lab) < 0)
+		pfatal("can't read disk label for %s\n", fname);
+
 	if (readboot(dosfs, &boot) != FSOK) {
 		(void)close(dosfs);
 		return (8);
diff --git a/sbin/fsck_msdos/ext.h b/sbin/fsck_msdos/ext.h
index 2fb233ecb82..5d5dd16516f 100644
--- a/sbin/fsck_msdos/ext.h
+++ b/sbin/fsck_msdos/ext.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ext.h,v 1.9 2008/02/07 01:34:12 ian Exp $	*/
+/*	$OpenBSD: ext.h,v 1.10 2012/03/31 17:53:34 krw Exp $	*/
 /*	$NetBSD: ext.h,v 1.5 1997/10/17 11:19:48 ws Exp $	*/
 
 /*
@@ -51,7 +51,7 @@ extern int alwaysyes;	/* assume "yes" for all questions */
 extern int preen;	/* we are preening */
 extern int rdonly;	/* device is opened read only (supersedes above) */
 
-extern char *fname;	/* filesystem currently checked */
+extern struct disklabel lab;
 
 extern struct dosDirEntry *rootDir;
 
diff --git a/sbin/fsck_msdos/main.c b/sbin/fsck_msdos/main.c
index 78faff06500..99c5fc620f5 100644
--- a/sbin/fsck_msdos/main.c
+++ b/sbin/fsck_msdos/main.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: main.c,v 1.17 2010/08/12 15:26:34 jsing Exp $	*/
+/*	$OpenBSD: main.c,v 1.18 2012/03/31 17:53:34 krw Exp $	*/
 /*	$NetBSD: main.c,v 1.8 1996/10/17 20:29:53 cgd Exp $	*/
 
 /*
@@ -98,7 +98,7 @@ main(int argc, char *argv[])
 
 	while (argc-- > 0) {
 		setcdevname(*argv, NULL, preen);
-		erg = checkfilesys(*argv++);
+		erg = checkfilesys(blockcheck(*argv++));
 		if (erg > ret)
 			ret = erg;
 	}