bin/116980: [patch] [msdosfs] mount_msdosfs(8) resets some flags for 'update' mount

[Eugene Grosbein]

>Number:         116980
>Category:       bin
>Synopsis:       [patch] [msdosfs] mount_msdosfs(8) resets some flags for 'update' mount
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sat Oct 06 19:30:00 GMT 2007
>Closed-Date:
>Last-Modified:
>Originator:     Eugene Grosbein
>Release:        FreeBSD 6.2-STABLE i386
>Organization:
Svyaz-Service JSC
>Environment:
System: FreeBSD grosbein.pp.ru 6.2-STABLE FreeBSD 6.2-STABLE #2: Sun Sep 16 16:54:23 KRAST 2007 eu at grosbein.pp.ru:/home/obj/usr/local/src/sys/DADV i386

>Description:
	"mount -t msdosfs -u -o rw" resets uid, gid, mask and dirmask
	to defauls but should keep current values.

>How-To-Repeat:

	1. Create FS with a file:

# dd if=/dev/zero bs=1k count=1440 of=image
# mdconfig -a -t vnode -f image
# newfs_msdos -f 1440 /dev/md0
# mount_msdosfs /dev/md0 /mnt/tmp
# touch /mnt/tmp/file
# umount /mnt/tmp

	2. Mount it with convenient flags, so directories are searchable
	and files are not executable, and read-only:

# mount_msdosfs -o ro -M 755 -m 644 /dev/md0 /mnt/tmp

	Make sure it works, file is not executable:

# ls -l /mnt/tmp
total 0
-rw-r--r--  1 root  wheel  0 Oct  7 03:05 file

	Now remount it read-write and see that mask has been reset:

# mount -u -o rw /mnt/tmp
# ls -l /mnt/tmp
total 0
-rwxr-xr-x  1 root  wheel  0 Oct  7 03:05 file

>Fix:

	mount_msdosfs(8) should not set defaults for update.

--- sbin/mount_msdosfs/mount_msdosfs.c.orig	2007-09-24 20:36:51.000000000 +0800
+++ sbin/mount_msdosfs/mount_msdosfs.c	2007-10-07 03:15:40.000000000 +0800
@@ -69,7 +69,7 @@
 	struct iovec *iov = NULL;
 	int iovlen = 0;
 	struct stat sb;
-	int c, mntflags, set_gid, set_uid, set_mask, set_dirmask;
+	int c, mntflags, set_gid, set_uid, set_mask, set_dirmask, update = 0;
 	char *dev, *dir, mntpath[MAXPATHLEN], *csp;
 	char fstype[] = "msdosfs";
 	char *cs_dos = NULL;
@@ -133,6 +133,7 @@
 				*p = '\0';
 				val = p + 1;
 			}
+			update = update || !strcmp(optarg, "update");
 			build_iovec(&iov, &iovlen, optarg, val, -1);
 			}
 			break;
@@ -165,13 +166,15 @@
 	if (optind + 2 != argc)
 		usage();
 
-	if (set_mask && !set_dirmask) {
-		dirmask = mask;
-		set_dirmask = 1;
-	}
-	else if (set_dirmask && !set_mask) {
-		mask = dirmask;
-		set_mask = 1;
+	if (!update) {
+		if (set_mask && !set_dirmask) {
+			dirmask = mask;
+			set_dirmask = 1;
+		}
+		else if (set_dirmask && !set_mask) {
+			mask = dirmask;
+			set_mask = 1;
+		}
 	}
 
 	dev = argv[optind];
@@ -195,26 +198,36 @@
 	(void)checkpath(dir, mntpath);
 	(void)rmslashes(dev, dev);
 
-	if (!set_gid || !set_uid || !set_mask) {
+	if (!update && (!set_gid || !set_uid || !set_mask)) {
 		if (stat(mntpath, &sb) == -1)
 			err(EX_OSERR, "stat %s", mntpath);
-
-		if (!set_uid)
+		if (!set_uid) {
 			uid = sb.st_uid;
-		if (!set_gid)
+			set_uid = 1;
+		}
+		if (!set_gid) {
 			gid = sb.st_gid;
-		if (!set_mask)
+			set_gid = 1;
+		}
+		if (!set_mask) {
 			mask = dirmask =
 				sb.st_mode & (S_IRWXU | S_IRWXG | S_IRWXO);
+			set_mask = set_dirmask = 1;
+		}
 	}
 
 	build_iovec(&iov, &iovlen, "fstype", fstype, -1);
 	build_iovec(&iov, &iovlen, "fspath", mntpath, -1);
 	build_iovec(&iov, &iovlen, "from", dev, -1);
-	build_iovec_argf(&iov, &iovlen, "uid", "%d", uid);
-	build_iovec_argf(&iov, &iovlen, "gid", "%u", gid);
-	build_iovec_argf(&iov, &iovlen, "mask", "%u", mask);
-	build_iovec_argf(&iov, &iovlen, "dirmask", "%u", dirmask);
+	
+	if (set_uid)
+		build_iovec_argf(&iov, &iovlen, "uid", "%d", uid);
+	if (set_gid)
+		build_iovec_argf(&iov, &iovlen, "gid", "%u", gid);
+	if (set_mask)
+		build_iovec_argf(&iov, &iovlen, "mask", "%u", mask);
+	if (set_dirmask)
+		build_iovec_argf(&iov, &iovlen, "dirmask", "%u", dirmask);
 
 	if (nmount(iov, iovlen, mntflags) < 0)
 		err(1, "%s", dev);


>Release-Note:
>Audit-Trail:
>Unformatted: