Restrict which filesystems are available for swap. This rules out

obvious misconfigurations that cannot work.

OK mpi@ tedu@

5 files changed, 26 insertions, 11 deletions

diff --git a/lib/libc/sys/swapctl.2 b/lib/libc/sys/swapctl.2
index ec000679783..35f4098dc40 100644
--- a/lib/libc/sys/swapctl.2
+++ b/lib/libc/sys/swapctl.2
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: swapctl.2,v 1.23 2018/04/27 13:42:08 guenther Exp $
+.\"	$OpenBSD: swapctl.2,v 1.24 2019/04/02 13:07:28 visa Exp $
 .\"	$NetBSD: swapctl.2,v 1.10 1998/08/29 17:11:09 mrg Exp $
 .\"
 .\" Copyright (c) 1997 Matthew R. Green
@@ -29,7 +29,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd $Mdocdate: April 27 2018 $
+.Dd $Mdocdate: April 2 2019 $
 .Dt SWAPCTL 2
 .Os
 .Sh NAME
@@ -210,6 +210,10 @@ An I/O error occurred while opening the swap device.
 .It Bq Er EFAULT
 .Fa arg
 points outside the process' allocated address space.
+.It Bq Er ENOTSUP
+The device specified by
+.Fa arg
+cannot be used for swapping.
 .El
 .Sh SEE ALSO
 .Xr config 8 ,
diff --git a/sys/kern/vfs_init.c b/sys/kern/vfs_init.c
index 78301377e97..adf1116645d 100644
--- a/sys/kern/vfs_init.c
+++ b/sys/kern/vfs_init.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vfs_init.c,v 1.41 2018/09/17 14:56:37 visa Exp $	*/
+/*	$OpenBSD: vfs_init.c,v 1.42 2019/04/02 13:07:28 visa Exp $	*/
 /*	$NetBSD: vfs_init.c,v 1.6 1996/02/09 19:00:58 christos Exp $	*/
 
 /*
@@ -93,7 +93,7 @@ extern  const struct vfsops tmpfs_vfsops;
 /* Set up the filesystem operations for vnodes. */
 static struct vfsconf vfsconflist[] = {
 #ifdef FFS
-        { &ffs_vfsops, MOUNT_FFS, 1, 0, MNT_LOCAL,
+        { &ffs_vfsops, MOUNT_FFS, 1, 0, MNT_LOCAL | MNT_SWAPPABLE,
 	    sizeof(struct ufs_args) },
 #endif
 
@@ -103,7 +103,7 @@ static struct vfsconf vfsconflist[] = {
 #endif
 
 #ifdef EXT2FS
-	{ &ext2fs_vfsops, MOUNT_EXT2FS, 17, 0, MNT_LOCAL,
+	{ &ext2fs_vfsops, MOUNT_EXT2FS, 17, 0, MNT_LOCAL | MNT_SWAPPABLE,
 	    sizeof(struct ufs_args) },
 #endif
 
@@ -113,12 +113,12 @@ static struct vfsconf vfsconflist[] = {
 #endif
 
 #ifdef MSDOSFS
-        { &msdosfs_vfsops, MOUNT_MSDOS, 4, 0, MNT_LOCAL,
+        { &msdosfs_vfsops, MOUNT_MSDOS, 4, 0, MNT_LOCAL | MNT_SWAPPABLE,
 	    sizeof(struct msdosfs_args) },
 #endif
 
 #ifdef NFSCLIENT
-        { &nfs_vfsops, MOUNT_NFS, 2, 0, 0,
+        { &nfs_vfsops, MOUNT_NFS, 2, 0, MNT_SWAPPABLE,
 	    sizeof(struct nfs_args) },
 #endif
 
diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index ed5bbd1be61..982e45080ca 100644
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vfs_subr.c,v 1.286 2019/02/17 22:17:28 tedu Exp $	*/
+/*	$OpenBSD: vfs_subr.c,v 1.287 2019/04/02 13:07:28 visa Exp $	*/
 /*	$NetBSD: vfs_subr.c,v 1.53 1996/04/22 01:39:13 christos Exp $	*/
 
 /*
@@ -184,7 +184,7 @@ vfs_mount_alloc(struct vnode *vp, struct vfsconf *vfsp)
 	atomic_inc_int(&vfsp->vfc_refcount);
 	mp->mnt_vfc = vfsp;
 	mp->mnt_op = vfsp->vfc_vfsops;
-	mp->mnt_flag = vfsp->vfc_flags & MNT_VISFLAGMASK;
+	mp->mnt_flag = vfsp->vfc_flags;
 	strncpy(mp->mnt_stat.f_fstypename, vfsp->vfc_name, MFSNAMELEN);
 
 	return (mp);
diff --git a/sys/sys/mount.h b/sys/sys/mount.h
index f11785cd0b6..6f1004324a3 100644
--- a/sys/sys/mount.h
+++ b/sys/sys/mount.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mount.h,v 1.143 2018/12/07 16:21:19 mpi Exp $	*/
+/*	$OpenBSD: mount.h,v 1.144 2019/04/02 13:07:28 visa Exp $	*/
 /*	$NetBSD: mount.h,v 1.48 1996/02/18 11:55:47 fvdl Exp $	*/
 
 /*
@@ -399,6 +399,7 @@ struct mount {
 #define	MNT_RELOAD	0x00040000	/* reload filesystem data */
 #define	MNT_FORCE	0x00080000	/* force unmount or readonly change */
 #define	MNT_STALLED	0x00100000	/* filesystem stalled */ 
+#define	MNT_SWAPPABLE	0x00200000	/* filesystem can be used for swap */
 #define MNT_WANTRDWR	0x02000000	/* want upgrade to read/write */
 #define MNT_SOFTDEP     0x04000000      /* soft dependencies being done */
 #define MNT_DOOMED	0x08000000	/* device behind filesystem is gone */
diff --git a/sys/uvm/uvm_swap.c b/sys/uvm/uvm_swap.c
index 663f05b9562..233908ca5e2 100644
--- a/sys/uvm/uvm_swap.c
+++ b/sys/uvm/uvm_swap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_swap.c,v 1.143 2018/02/19 08:59:53 mpi Exp $	*/
+/*	$OpenBSD: uvm_swap.c,v 1.144 2019/04/02 13:07:28 visa Exp $	*/
 /*	$NetBSD: uvm_swap.c,v 1.40 2000/11/17 11:39:39 mrg Exp $	*/
 
 /*
@@ -714,6 +714,16 @@ sys_swapctl(struct proc *p, void *v, register_t *retval)
 		break;
 	case SWAP_ON:
 		/*
+		 * If the device is a regular file, make sure the filesystem
+		 * can be used for swapping.
+		 */
+		if (vp->v_type == VREG &&
+		    (vp->v_mount->mnt_flag & MNT_SWAPPABLE) == 0) {
+			error = ENOTSUP;
+			break;
+		}
+
+		/*
 		 * check for duplicates.   if none found, then insert a
 		 * dummy entry on the list to prevent someone else from
 		 * trying to enable this device while we are working on