bin/151976: mount_nullfs patch to add support for exposing sockets and fifos of layered filesystems

[John Hixson]

>Number:         151976
>Category:       bin
>Synopsis:       mount_nullfs patch to add support for exposing sockets and fifos of layered filesystems
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          update
>Submitter-Id:   current-users
>Arrival-Date:   Sat Nov 06 00:20:05 UTC 2010
>Closed-Date:
>Last-Modified:
>Originator:     John Hixson
>Release:        9.0-CURRENT
>Organization:
iXsystems
>Environment:
FreeBSD thinkbsd 9.0-CURRENT FreeBSD 9.0-CURRENT #11: Fri Oct 29 04:51:53 PDT 2010     john at thinkbsd:/usr/obj/usr/src/sys/THINKBSD  amd64

>Description:
Update to PR 151736 , which would panic. 
>How-To-Repeat:

>Fix:


Patch attached with submission follows:

diff -urN sbin/mount_nullfs.orig/mount_nullfs.8 sbin/mount_nullfs/mount_nullfs.8
--- sbin/mount_nullfs.orig/mount_nullfs.8	2006-04-19 12:21:42.000000000 -0700
+++ sbin/mount_nullfs/mount_nullfs.8	2010-10-25 16:50:35.000000000 -0700
@@ -73,6 +73,8 @@
 .Pp
 The options are as follows:
 .Bl -tag -width indent
+.It Fl i
+Expose sockets and fifos across the nullfs mounted filesystem.
 .It Fl o
 Options are specified with a
 .Fl o
@@ -80,6 +82,13 @@
 See the
 .Xr mount 8
 man page for possible options and their meanings.
+The following nullfs specific options are available:
+.Pp
+.Bl -tag -width "ipc" -compact
+.It Cm ipc
+Same as
+.Fl i .
+.El
 .El
 .Pp
 The null layer has two purposes.
diff -urN sbin/mount_nullfs.orig/mount_nullfs.c sbin/mount_nullfs/mount_nullfs.c
--- sbin/mount_nullfs.orig/mount_nullfs.c	2009-12-29 14:53:27.000000000 -0800
+++ sbin/mount_nullfs/mount_nullfs.c	2010-10-25 16:57:31.000000000 -0700
@@ -48,6 +48,8 @@
 #include <sys/mount.h>
 #include <sys/uio.h>
 
+#include <fs/nullfs/null.h>
+
 #include <err.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -68,16 +70,25 @@
 int
 main(int argc, char *argv[])
 {
-	struct iovec iov[6];
-	int ch, mntflags;
+	struct iovec *iov;
 	char source[MAXPATHLEN];
 	char target[MAXPATHLEN];
+	char fstype[] = "nullfs";
+	int ch, iovlen, mntflags, nullfs_flags;
 
-	mntflags = 0;
-	while ((ch = getopt(argc, argv, "o:")) != -1)
+	iov = NULL;
+	getmnt_silent = 1;
+	iovlen = mntflags = nullfs_flags = 0;
+	while ((ch = getopt(argc, argv, "io:")) != -1)
 		switch(ch) {
+		case 'i':
+			nullfs_flags |= NULLFSMNT_IPC;
+			break;
 		case 'o':
 			getmntopts(optarg, mopts, &mntflags, 0);
+			if (strncmp(optarg, "ipc", 3) == 0)
+				nullfs_flags |= NULLFSMNT_IPC;
+
 			break;
 		case '?':
 		default:
@@ -97,20 +108,14 @@
 		errx(EX_USAGE, "%s (%s) and %s are not distinct paths",
 		    argv[0], target, argv[1]);
 
-	iov[0].iov_base = strdup("fstype");
-	iov[0].iov_len = sizeof("fstype");
-	iov[1].iov_base = strdup("nullfs");
-	iov[1].iov_len = strlen(iov[1].iov_base) + 1;
-	iov[2].iov_base = strdup("fspath");
-	iov[2].iov_len = sizeof("fspath");
-	iov[3].iov_base = source;
-	iov[3].iov_len = strlen(source) + 1;
-	iov[4].iov_base = strdup("target");
-	iov[4].iov_len = sizeof("target");
-	iov[5].iov_base = target;
-	iov[5].iov_len = strlen(target) + 1;
+	build_iovec(&iov, &iovlen, "fstype", fstype, (size_t)-1);
+	build_iovec(&iov, &iovlen, "fspath", source, (size_t)-1);
+	build_iovec(&iov, &iovlen, "target", target, (size_t)-1);
+
+	if (nullfs_flags & NULLFSMNT_IPC)
+		build_iovec(&iov, &iovlen, "ipc", NULL, 0);
 
-	if (nmount(iov, 6, mntflags))
+	if (nmount(iov, iovlen, mntflags))
 		err(1, NULL);
 	exit(0);
 }
@@ -134,6 +139,6 @@
 usage(void)
 {
 	(void)fprintf(stderr,
-		"usage: mount_nullfs [-o options] target mount-point\n");
+		"usage: mount_nullfs [-o options] [-i] target mount-point\n");
 	exit(1);
 }
diff -urN sys/fs/nullfs.orig/null.h sys/fs/nullfs/null.h
--- sys/fs/nullfs.orig/null.h	2005-03-15 05:49:33.000000000 -0800
+++ sys/fs/nullfs/null.h	2010-10-25 11:19:16.000000000 -0700
@@ -39,6 +39,8 @@
 	struct vnode	*nullm_rootvp;	/* Reference to root null_node */
 };
 
+#define	NULLFSMNT_IPC	0x00000001
+
 #ifdef _KERNEL
 /*
  * A cache of vnode references
diff -urN sys/fs/nullfs.orig/null_subr.c sys/fs/nullfs/null_subr.c
--- sys/fs/nullfs.orig/null_subr.c	2009-05-31 07:54:20.000000000 -0700
+++ sys/fs/nullfs/null_subr.c	2010-10-25 16:55:31.000000000 -0700
@@ -230,6 +230,11 @@
 	xp->null_vnode = vp;
 	xp->null_lowervp = lowervp;
 	vp->v_type = lowervp->v_type;
+
+	if (vp->v_type == VSOCK || vp->v_type == VFIFO)
+		if (vfs_getopt(mp->mnt_optnew, "ipc", NULL, NULL) == 0)
+	 		vp->v_un = lowervp->v_un;
+
 	vp->v_data = xp;
 	vp->v_vnlock = lowervp->v_vnlock;
 	if (vp->v_vnlock == NULL)


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