6 files changed, 950 insertions, 1 deletions

diff --git a/sys/conf/files b/sys/conf/files
index 97ae16efe46fc..7a596ce96ec32 100644
--- a/sys/conf/files
+++ b/sys/conf/files
@@ -677,6 +677,7 @@ dev/xe/if_xe_pccard.c		optional xe card
 dev/xe/if_xe_pccard.c		optional xe pccard
 fs/deadfs/dead_vnops.c	standard
 fs/devfs/devfs_devs.c		standard
+fs/devfs/devfs_rule.c		standard
 fs/devfs/devfs_vfsops.c		standard
 fs/devfs/devfs_vnops.c		standard
 fs/fdescfs/fdesc_vfsops.c	optional fdescfs
diff --git a/sys/fs/devfs/devfs.h b/sys/fs/devfs/devfs.h
index 137797f4c8dbf..2f0dc762018b2 100644
--- a/sys/fs/devfs/devfs.h
+++ b/sys/fs/devfs/devfs.h
@@ -3,6 +3,8 @@
  *	The Regents of the University of California.  All rights reserved.
  * Copyright (c) 2000
  *	Poul-Henning Kamp.  All rights reserved.
+ * Copyright (c) 2002
+ *	Dima Dorfman.  All rights reserved.
  *
  * This code is derived from software donated to Berkeley by
  * Jan-Simon Pendry.
@@ -37,7 +39,86 @@
 #ifndef _FS_DEVFS_DEVFS_H_
 #define	_FS_DEVFS_DEVFS_H_
 
-#ifdef _KERNEL	/* No userland stuff in here... */
+#define	DEVFS_MAGIC	0xdb0a087a
+
+/*
+ * Identifiers.  The ruleset and rule numbers are 16-bit values.  The
+ * "rule ID" is a combination of the ruleset and rule number; it
+ * should be able to univocally describe a rule in the system.  In
+ * this implementation, the upper 16 bits of the rule ID is the
+ * ruleset number; the lower 16 bits, the rule number within the
+ * aforementioned ruleset.
+ */
+typedef uint16_t devfs_rnum;
+typedef uint16_t devfs_rsnum;
+typedef uint32_t devfs_rid;
+
+/*
+ * Identifier manipulators.
+ */
+#define	rid2rsn(rid)	((rid) >> 16)
+#define	rid2rn(rid)	((rid) & 0xffff)
+#define	mkrid(rsn, rn)	((rn) | ((rsn) << 16))
+
+/*
+ * Plain DEVFS rule.  This gets shared between kernel and userland
+ * verbatim, so it shouldn't contain any pointers or other kernel- or
+ * userland-specific values.
+ */
+struct devfs_rule {
+	uint32_t dr_magic;			/* Magic number. */
+	devfs_rid dr_id;			/* Identifier. */
+
+	/*
+	 * Conditions under which this rule should be applied.  These
+	 * are ANDed together since OR can be simulated by using
+	 * multiple rules.  dr_icond determines which of the other
+	 * variables we should process.
+	 */
+	int	dr_icond;
+#define	DRC_DSWFLAGS	0x001
+#define	DRC_PATHPTRN	0x002
+#define	DRC_MAJOR	0x004
+	int	dr_dswflags;			/* cdevsw flags to match. */
+#define	DEVFS_MAXPTRNLEN	200
+	char	dr_pathptrn[DEVFS_MAXPTRNLEN];	/* Pattern to match path. */
+	int	dr_major;			/* Device major number. */
+
+	/*
+	 * Things to change.  dr_iacts determines which of the other
+	 * variables we should process.
+	 */
+	int	dr_iacts;
+#define	DRA_BACTS	0x001
+#define DRA_UID		0x002
+#define	DRA_GID		0x004
+#define	DRA_MODE	0x008
+#define	DRA_INCSET	0x010
+	int	dr_bacts;			/* Boolean (on/off) action. */
+#define	DRB_HIDE	0x001			/* Hide entry (DE_WHITEOUT). */
+#define	DRB_UNHIDE	0x002			/* Unhide entry. */
+	uid_t	dr_uid;
+	gid_t	dr_gid;
+	mode_t	dr_mode;
+	devfs_rsnum dr_incset;			/* Included ruleset. */
+};
+
+/*
+ * Rule-related ioctls.
+ */
+#define	DEVFSIO_RADD		_IOWR('D', 0, struct devfs_rule)
+#define	DEVFSIO_RDEL		_IOW('D', 1, devfs_rid)
+#define	DEVFSIO_RAPPLY		_IOW('D', 2, struct devfs_rule)
+#define	DEVFSIO_RAPPLYID	_IOW('D', 3, devfs_rid)
+#define	DEVFSIO_RGETNEXT       	_IOWR('D', 4, struct devfs_rule)
+
+#define	DEVFSIO_SUSE		_IOW('D', 10, devfs_rsnum)
+#define	DEVFSIO_SAPPLY		_IOW('D', 11, devfs_rsnum)
+#define	DEVFSIO_SGETNEXT	_IOWR('D', 12, devfs_rsnum)
+
+/* XXX: DEVFSIO_RS_GET_INFO for refcount, active if any, etc. */
+
+#ifdef _KERNEL
 
 /*
  * These are default sizes for the DEVFS inode table and the overflow
@@ -94,6 +175,7 @@ struct devfs_mount {
 	struct devfs_dirent **dm_overflow;
 	int	dm_inode;
 	struct lock dm_lock;
+	devfs_rsnum dm_ruleset;
 };
 
 /*
@@ -106,6 +188,10 @@ struct devfs_mount {
 extern vop_t **devfs_vnodeop_p;
 extern vop_t **devfs_specop_p;
 
+void devfs_rules_apply(struct devfs_mount *dm, struct devfs_dirent *de);
+void devfs_rules_init(void);
+int devfs_rules_ioctl(struct mount *mp, int cmd, caddr_t data, struct thread *td);
+void devfs_rules_newmount(struct devfs_mount *dm, struct thread *td);
 int devfs_allocv (struct devfs_dirent *de, struct mount *mp, struct vnode **vpp, struct thread *td);
 dev_t *devfs_itod (int inode);
 struct devfs_dirent **devfs_itode (struct devfs_mount *dm, int inode);
diff --git a/sys/fs/devfs/devfs_devs.c b/sys/fs/devfs/devfs_devs.c
index ef9827cf5e45b..fd378b8c0ca25 100644
--- a/sys/fs/devfs/devfs_devs.c
+++ b/sys/fs/devfs/devfs_devs.c
@@ -352,6 +352,7 @@ devfs_populate(struct devfs_mount *dm)
 			}
 			*dep = de;
 			de->de_dir = dd;
+			devfs_rules_apply(dm, de);
 			TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
 #if 0
 			printf("Add ino%d %s\n", i, dev->si_name);
@@ -435,6 +436,7 @@ devfs_init(void *junk)
 	devfs_create_hook = devfs_create;
 	devfs_destroy_hook = devfs_destroy;
 	devfs_present = 1;
+	devfs_rules_init();
 }
 
 SYSINIT(devfs, SI_SUB_DEVFS, SI_ORDER_FIRST, devfs_init, NULL);
diff --git a/sys/fs/devfs/devfs_rule.c b/sys/fs/devfs/devfs_rule.c
new file mode 100644
index 0000000000000..3f19da2c30545
--- /dev/null
+++ b/sys/fs/devfs/devfs_rule.c
@@ -0,0 +1,839 @@
+/*-
+ * Copyright (c) 2002 Dima Dorfman.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * 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.
+ *
+ * $FreeBSD$
+ */
+
+/*
+ * DEVFS ruleset implementation.
+ *
+ * A note on terminology: To "run" a rule on a dirent is to take the
+ * prescribed action; to "apply" a rule is to check whether it matches
+ * a dirent and run if if it does.
+ *
+ * A note on locking: Only foreign entry points (non-static functions)
+ * should deal with locking.  Everything else assumes we already hold
+ * the required kind of lock.
+ *
+ * A note on namespace: devfs_rules_* are the non-static functions for
+ * the entire "ruleset" subsystem, devfs_rule_* are the static
+ * functions that operate on rules, and devfs_ruleset_* are the static
+ * functions that operate on rulesets.  The line between the last two
+ * isn't always clear, but the guideline is still useful.
+ *
+ * A note on "special" identifiers: Ruleset 0 is the NULL, or empty,
+ * ruleset; it cannot be deleted or changed in any way.  This may be
+ * assumed inside the code; e.g., a ruleset of 0 may be interpeted to
+ * mean "no ruleset".  The interpretation of rule 0 is
+ * command-dependent, but in no case is there a real rule with number
+ * 0.
+ *
+ * A note on errno codes: To make it easier for the userland to tell
+ * what went wrong, we sometimes use errno codes that are not entirely
+ * appropriate for the error but that would be less ambiguous than the
+ * appropriate "generic" code.  For example, when we can't find a
+ * ruleset, we return ESRCH instead of ENOENT (except in
+ * DEVFSIO_{R,S}GETNEXT, where a nonexistent ruleset means "end of
+ * list", and the userland expects ENOENT to be this indicator); this
+ * way, when an operation fails, it's clear that what couldn't be
+ * found is a ruleset and not a rule (well, it's clear to those who
+ * know the convention).
+ */
+
+#include "opt_devfs.h"
+#ifndef NODEVFS
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/conf.h>
+#include <sys/kernel.h>
+#include <sys/malloc.h>
+#include <sys/dirent.h>
+#include <sys/vnode.h>
+#include <sys/mount.h>
+#include <sys/ioccom.h>
+
+#include <fs/devfs/devfs.h>
+
+
+/*
+ * Kernel version of devfs_rule.
+ */
+struct devfs_krule {
+	SLIST_ENTRY(devfs_krule) dk_list;
+	struct devfs_ruleset *dk_ruleset;
+	struct devfs_rule dk_rule;
+};
+
+/*
+ * Structure to describe a ruleset.
+ */
+struct devfs_ruleset {
+	SLIST_ENTRY(devfs_ruleset) ds_list;
+	devfs_rsnum ds_number;
+	SLIST_HEAD(, devfs_krule) ds_rules;
+	int	ds_refcount;
+	int	ds_flags;
+#define	DS_IMMUTABLE	0x001
+};
+
+static devfs_rid devfs_rid_input(devfs_rid rid, struct devfs_mount *dm);
+
+static void devfs_rule_applyde(struct devfs_krule *dk,struct devfs_dirent *de);
+static void devfs_rule_applyde_recursive(struct devfs_krule *dk,
+		struct devfs_dirent *de);
+static void devfs_rule_applydm(struct devfs_krule *dk, struct devfs_mount *dm);
+static int  devfs_rule_autonumber(struct devfs_ruleset *ds, devfs_rnum *rnp);
+static struct devfs_krule *devfs_rule_byid(devfs_rid rid);
+static int  devfs_rule_delete(struct devfs_krule **dkp);
+static dev_t devfs_rule_getdev(struct devfs_dirent *de);
+static int  devfs_rule_input(struct devfs_rule *dr, struct devfs_mount *dm);
+static int  devfs_rule_insert(struct devfs_rule *dr);
+static int  devfs_rule_match(struct devfs_krule *dk, struct devfs_dirent *de);
+static int  devfs_rule_matchpath(struct devfs_krule *dk,
+		struct devfs_dirent *de);
+static void devfs_rule_run(struct devfs_krule *dk, struct devfs_dirent *de);
+
+static void devfs_ruleset_applyde(struct devfs_ruleset *ds,
+		struct devfs_dirent *de);
+static void devfs_ruleset_applydm(struct devfs_ruleset *ds,
+		struct devfs_mount *dm);
+static struct devfs_ruleset *devfs_ruleset_bynum(devfs_rsnum rsnum);
+static struct devfs_ruleset *devfs_ruleset_create(devfs_rsnum rsnum);
+static void devfs_ruleset_destroy(struct devfs_ruleset **dsp);
+static void devfs_ruleset_reap(struct devfs_ruleset **dsp);
+static int  devfs_ruleset_use(devfs_rsnum rsnum, struct devfs_mount *dm);
+
+static SLIST_HEAD(, devfs_ruleset) devfs_rulesets;
+
+/*
+ * Called to apply the proper rules for de before the latter can be
+ * exposed to the userland.  This should be called with an exclusive
+ * lock on dm in case we need to run anything.
+ */
+void
+devfs_rules_apply(struct devfs_mount *dm, struct devfs_dirent *de)
+{
+	struct devfs_ruleset *ds;
+
+	ds = devfs_ruleset_bynum(dm->dm_ruleset);
+	KASSERT(ds != NULL, ("mount-point has NULL ruleset"));
+	devfs_ruleset_applyde(ds, de);
+}
+
+/*
+ * Rule subsystem SYSINIT hook.
+ */
+void
+devfs_rules_init(void)
+{
+	struct devfs_ruleset *ds;
+
+	SLIST_INIT(&devfs_rulesets);
+
+	ds = devfs_ruleset_create(0);
+	ds->ds_flags |= DS_IMMUTABLE;
+	ds->ds_refcount = 1;		/* Prevent reaping. */
+}
+
+/*
+ * Rule subsystem ioctl hook.
+ */
+int
+devfs_rules_ioctl(struct mount *mp, int cmd, caddr_t data, struct thread *td)
+{
+	struct devfs_mount *dm = VFSTODEVFS(mp);
+	struct devfs_ruleset *ds;
+	struct devfs_krule *dk;
+	struct devfs_rule *dr;
+	devfs_rsnum rsnum;
+	devfs_rnum rnum;
+	devfs_rid rid;
+	int error;
+
+	/*
+	 * XXX: This returns an error regardless of whether we
+	 * actually support the cmd or not.
+	 */
+	error = suser(td);
+	if (error != 0)
+		return (error);
+
+	lockmgr(&dm->dm_lock, LK_SHARED, 0, td);
+
+	switch (cmd) {
+	case DEVFSIO_RADD:
+		dr = (struct devfs_rule *)data;
+		error = devfs_rule_input(dr, dm);
+		if (error != 0)
+			goto out;
+		dk = devfs_rule_byid(dr->dr_id);
+		if (dk != NULL) {
+			error = EEXIST;
+			goto out;
+		}
+		lockmgr(&dm->dm_lock, LK_UPGRADE, 0, td);
+		error = devfs_rule_insert(dr);
+		break;
+	case DEVFSIO_RAPPLY:
+		dr = (struct devfs_rule *)data;
+		error = devfs_rule_input(dr, dm);
+		if (error != 0)
+			goto out;
+
+		/*
+		 * This is one of many possible hackish
+		 * implementations.  The primary contender is an
+		 * implementation where the rule we read in is
+		 * temporarily inserted into some ruleset, perhaps
+		 * with a hypothetical DRO_NOAUTO flag so that it
+		 * doesn't get used where it isn't intended, and
+		 * applied in the normal way.  This can be done in the
+		 * userland (DEVFSIO_ADD, DEVFSIO_APPLYID,
+		 * DEVFSIO_DEL) or in the kernel; either way it breaks
+		 * some corner case assumptions in other parts of the
+		 * code (not that this implementation doesn't do
+		 * that).
+		 */
+		if (dr->dr_iacts & DRA_INCSET &&
+		    devfs_ruleset_bynum(dr->dr_incset) == NULL) {
+			error = ESRCH;
+			goto out;
+		}
+		dk = malloc(sizeof(*dk), M_TEMP, M_WAITOK | M_ZERO);
+		memcpy(&dk->dk_rule, dr, sizeof(*dr));
+		lockmgr(&dm->dm_lock, LK_UPGRADE, 0, td);
+		devfs_rule_applydm(dk, dm);
+		lockmgr(&dm->dm_lock, LK_DOWNGRADE, 0, td);
+		free(dk, M_TEMP);
+		error = 0;
+		break;
+	case DEVFSIO_RAPPLYID:
+		rid = *(devfs_rid *)data;
+		rid = devfs_rid_input(rid, dm);
+		dk = devfs_rule_byid(rid);
+		if (dk == NULL) {
+			error = ENOENT;
+			goto out;
+		}
+		lockmgr(&dm->dm_lock, LK_UPGRADE, 0, td);
+		devfs_rule_applydm(dk, dm);
+		error = 0;
+		break;
+	case DEVFSIO_RDEL:
+		rid = *(devfs_rid *)data;
+		rid = devfs_rid_input(rid, dm);
+		dk = devfs_rule_byid(rid);
+		if (dk == NULL) {
+			error = ENOENT;
+			goto out;
+		}
+		ds = dk->dk_ruleset;
+		lockmgr(&dm->dm_lock, LK_UPGRADE, 0, td);
+		error = devfs_rule_delete(&dk);
+		devfs_ruleset_reap(&ds);
+		break;
+	case DEVFSIO_RGETNEXT:
+		dr = (struct devfs_rule *)data;
+		error = devfs_rule_input(dr, dm);
+		if (error != 0)
+			goto out;
+		/*
+		 * We can't use devfs_rule_byid() here since that
+		 * requires the rule specified to exist, but we want
+		 * getnext(N) to work whether there is a rule N or not
+		 * (specifically, getnext(0) must work, but we should
+		 * never have a rule 0 since the add command
+		 * interprets 0 to mean "auto-number").
+		 */
+		ds = devfs_ruleset_bynum(rid2rsn(dr->dr_id));
+		if (ds == NULL) {
+			error = ENOENT;
+			goto out;
+		}
+		rnum = rid2rn(dr->dr_id);
+		SLIST_FOREACH(dk, &ds->ds_rules, dk_list) {
+			if (rid2rn(dk->dk_rule.dr_id) > rnum)
+				break;
+		}
+		if (dk == NULL) {
+			error = ENOENT;
+			goto out;
+		}
+		memcpy(dr, &dk->dk_rule, sizeof(*dr));
+		error = 0;
+		break;
+	case DEVFSIO_SUSE:
+		rsnum = *(devfs_rsnum *)data;
+		lockmgr(&dm->dm_lock, LK_UPGRADE, 0, td);
+		error = devfs_ruleset_use(rsnum, dm);
+		break;
+	case DEVFSIO_SAPPLY:
+		rsnum = *(devfs_rsnum *)data;
+		rsnum = rid2rsn(devfs_rid_input(mkrid(rsnum, 0), dm));
+		ds = devfs_ruleset_bynum(rsnum);
+		if (ds == NULL) {
+			error = ESRCH;
+			goto out;
+		}
+		lockmgr(&dm->dm_lock, LK_UPGRADE, 0, td);
+		devfs_ruleset_applydm(ds, dm);
+		error = 0;
+		break;
+	case DEVFSIO_SGETNEXT:
+		rsnum = *(devfs_rsnum *)data;
+		SLIST_FOREACH(ds, &devfs_rulesets, ds_list) {
+			if (ds->ds_number > rsnum)
+				break;
+		}
+		if (ds == NULL)
+			error = ENOENT;
+		else {
+			*(devfs_rsnum *)data = ds->ds_number;
+			error = 0;
+		}
+		break;
+	default:
+		error = ENOIOCTL;
+		break;
+	}
+
+out:
+	lockmgr(&dm->dm_lock, LK_RELEASE, 0, td);
+	return (error);
+}
+
+/*
+ * Called to initialize dm_ruleset when there is a new mount-point.
+ */
+void
+devfs_rules_newmount(struct devfs_mount *dm, struct thread *td)
+{
+	struct devfs_ruleset *ds;
+
+	lockmgr(&dm->dm_lock, LK_EXCLUSIVE, 0, td);
+	/*
+	 * We can't use devfs_ruleset_use() since it will try to
+	 * decrement the refcount for the old ruleset, and there is no
+	 * old ruleset.  Making some value of ds_ruleset "special" to
+	 * mean "don't decrement refcount" is uglier than this.
+	 */
+	ds = devfs_ruleset_bynum(0);
+	KASSERT(ds != NULL, ("no ruleset 0"));
+	++ds->ds_refcount;
+	dm->dm_ruleset = 0;
+	lockmgr(&dm->dm_lock, LK_RELEASE, 0, td);
+}
+
+/*
+ * Adjust the rule identifier to use the ruleset of dm if one isn't
+ * explicitly specified.
+ *
+ * Note that after this operation, rid2rsn(rid) might still be 0, and
+ * that's okay; ruleset 0 is a valid ruleset, but when it's read in
+ * from the userland, it means "current ruleset for this mount-point".
+ */
+static devfs_rid
+devfs_rid_input(devfs_rid rid, struct devfs_mount *dm)
+{
+
+	if (rid2rsn(rid) == 0)
+		return (mkrid(dm->dm_ruleset, rid2rn(rid)));
+	else
+		return (rid);
+}
+
+/*
+ * Apply dk to de.
+ */
+static void
+devfs_rule_applyde(struct devfs_krule *dk, struct devfs_dirent *de)
+{
+
+	if (devfs_rule_match(dk, de))
+		devfs_rule_run(dk, de);
+}
+
+/*
+ * Apply dk to de and everything under de.
+ *
+ * XXX: This method needs a function call for every nested
+ * subdirectory in a devfs mount.  If we plan to have many of these,
+ * we might eventually run out of kernel stack space.
+ */
+static void
+devfs_rule_applyde_recursive(struct devfs_krule *dk, struct devfs_dirent *de)
+{
+	struct devfs_dirent *de2;
+
+	/* XXX: Should we apply to ourselves first or last?  Does it matter? */
+	TAILQ_FOREACH(de2, &de->de_dlist, de_list) {
+		devfs_rule_applyde_recursive(dk, de2);
+	}
+	devfs_rule_applyde(dk, de);
+}
+
+/*
+ * Apply dk to all entires in dm.
+ */
+static void
+devfs_rule_applydm(struct devfs_krule *dk, struct devfs_mount *dm)
+{
+
+	devfs_rule_applyde_recursive(dk, dm->dm_basedir);
+}
+
+/*
+ * Automatically select a number for a new rule in ds, and write the
+ * result into rnump.
+ */
+static int
+devfs_rule_autonumber(struct devfs_ruleset *ds, devfs_rnum *rnump)
+{
+	struct devfs_krule *dk;
+
+	/* Find the last rule. */
+	SLIST_FOREACH(dk, &ds->ds_rules, dk_list) {
+		if (SLIST_NEXT(dk, dk_list) == NULL)
+			break;
+	}
+	if (dk == NULL)
+		*rnump = 100;
+	else {
+		*rnump = rid2rn(dk->dk_rule.dr_id) + 100;
+		/* Detect overflow. */
+		if (*rnump < rid2rn(dk->dk_rule.dr_id))
+			return (ERANGE);
+	}
+	KASSERT(devfs_rule_byid(mkrid(ds->ds_number, *rnump)) == NULL,
+	    ("autonumbering resulted in an already existing rule"));
+	return (0);
+}
+
+/*
+ * Find a krule by id.
+ */
+static struct devfs_krule *
+devfs_rule_byid(devfs_rid rid)
+{
+	struct devfs_ruleset *ds;
+	struct devfs_krule *dk;
+	devfs_rnum rn;
+
+	rn = rid2rn(rid);
+	ds = devfs_ruleset_bynum(rid2rsn(rid));
+	if (ds == NULL)
+		return (NULL);
+	SLIST_FOREACH(dk, &ds->ds_rules, dk_list) {
+		if (rid2rn(dk->dk_rule.dr_id) == rn)
+			return (dk);
+		else if (rid2rn(dk->dk_rule.dr_id) > rn)
+			break;
+	}
+	return (NULL);
+}
+
+/*
+ * Remove dkp from any lists it may be on and remove memory associated
+ * with it.
+ */
+static int
+devfs_rule_delete(struct devfs_krule **dkp)
+{
+	struct devfs_krule *dk = *dkp;
+	struct devfs_ruleset *ds;
+
+	if (dk->dk_rule.dr_iacts & DRA_INCSET) {
+		ds = devfs_ruleset_bynum(dk->dk_rule.dr_incset);
+		KASSERT(ds != NULL, ("DRA_INCSET but bad dr_incset"));
+		--ds->ds_refcount;
+		devfs_ruleset_reap(&ds);
+	}
+	SLIST_REMOVE(&dk->dk_ruleset->ds_rules, dk, devfs_krule, dk_list);
+	free(dk, M_DEVFS);
+	*dkp = NULL;
+	return (0);
+}
+
+/*
+ * Get a dev_t corresponding to de so we can try to match rules based
+ * on it.  If this routine returns NULL, there is no dev_t associated
+ * with the dirent (symlinks and directories don't have dev_ts), and
+ * the caller should assume that any critera dependent on a dev_t
+ * don't match.
+ */
+static dev_t
+devfs_rule_getdev(struct devfs_dirent *de)
+{
+	dev_t *devp, dev;
+
+	devp = devfs_itod(de->de_inode);
+	if (devp != NULL)
+		dev = *devp;
+	else
+		dev = NULL;
+	/* If we think this dirent should have a dev_t, alert the user. */
+	if (dev == NULL && de->de_dirent->d_type != DT_LNK &&
+	    de->de_dirent->d_type != DT_DIR)
+		printf("Warning: no dev_t for %s\n", de->de_dirent->d_name);
+	return (dev);
+}
+
+/*
+ * Do what we need to do to a rule that we just loaded from the
+ * userland.  In particular, we need to check the magic, and adjust
+ * the ruleset appropriate if desired.
+ */
+static int
+devfs_rule_input(struct devfs_rule *dr, struct devfs_mount *dm)
+{
+
+	if (dr->dr_magic != DEVFS_MAGIC)
+		return (ERPCMISMATCH);
+	dr->dr_id = devfs_rid_input(dr->dr_id, dm);
+	return (0);
+}
+
+/*
+ * Import dr into the appropriate place in the kernel (i.e., make a
+ * krule).  The value of dr is copied, so the pointer may be destroyed
+ * after this call completes.
+ */
+static int
+devfs_rule_insert(struct devfs_rule *dr)
+{
+	struct devfs_ruleset *ds, *dsi;
+	struct devfs_krule *k1, *k2;
+	struct devfs_krule *dk;
+	devfs_rsnum rsnum;
+	devfs_rnum dkrn;
+	int error;
+
+	/*
+	 * This stuff seems out of place here, but we want to do it as
+	 * soon as possible so that if it fails, we don't have to roll
+	 * back any changes we already made (e.g., ruleset creation).
+	 */
+	if (dr->dr_iacts & DRA_INCSET) {
+		dsi = devfs_ruleset_bynum(dr->dr_incset);
+		if (dsi == NULL)
+			return (ESRCH);
+	} else
+		dsi = NULL;
+
+	rsnum = rid2rsn(dr->dr_id);
+	ds = devfs_ruleset_bynum(rsnum);
+	if (ds == NULL)
+		ds = devfs_ruleset_create(rsnum);
+	if (ds->ds_flags & DS_IMMUTABLE)
+		return (EIO);
+	dkrn = rid2rn(dr->dr_id);
+	if (dkrn == 0) {
+		error = devfs_rule_autonumber(ds, &dkrn);
+		if (error != 0)
+			return (error);
+	}
+
+	dk = malloc(sizeof(*dk), M_DEVFS, M_WAITOK);
+	dk->dk_ruleset = ds;
+	if (dsi != NULL)
+		++dsi->ds_refcount;
+	/* XXX: Inspect dr? */
+	memcpy(&dk->dk_rule, dr, sizeof(*dr));
+	dk->dk_rule.dr_id = mkrid(rid2rsn(dk->dk_rule.dr_id), dkrn);
+
+	k1 = SLIST_FIRST(&ds->ds_rules);
+	if (k1 == NULL || rid2rn(k1->dk_rule.dr_id) > dkrn)
+		SLIST_INSERT_HEAD(&ds->ds_rules, dk, dk_list);
+	else {
+		SLIST_FOREACH(k1, &ds->ds_rules, dk_list) {
+			k2 = SLIST_NEXT(k1, dk_list);
+			if (k2 == NULL || rid2rn(k2->dk_rule.dr_id) > dkrn) {
+				SLIST_INSERT_AFTER(k1, dk, dk_list);
+				break;
+			}
+		}
+	}
+
+	return (0);
+}
+
+/*
+ * Determine whether dk matches de.  Returns 1 if dk should be run on
+ * de; 0, otherwise.
+ */
+static int
+devfs_rule_match(struct devfs_krule *dk, struct devfs_dirent *de)
+{
+	struct devfs_rule *dr = &dk->dk_rule;
+	dev_t dev;
+
+	dev = devfs_rule_getdev(de);
+	/*
+	 * At this point, if dev is NULL, we should assume that any
+	 * criteria that depend on it don't match.  We should *not*
+	 * just ignore them (i.e., act like they weren't specified),
+	 * since that makes a rule that only has criteria dependent on
+	 * the dev_t match all symlinks and directories.
+	 *
+	 * Note also that the following tests are somewhat reversed:
+	 * They're actually testing to see whether the condition does
+	 * *not* match, since the default is to assume the rule should
+	 * be run (such as if there are no conditions).
+	 */
+	if (dr->dr_icond & DRC_DSWFLAGS)
+		if (dev == NULL ||
+		    (dev->si_devsw->d_flags & dr->dr_dswflags) == 0)
+			goto nomatch;
+	if (dr->dr_icond & DRC_PATHPTRN)
+		if (!devfs_rule_matchpath(dk, de))
+			goto nomatch;
+	if (dr->dr_icond & DRC_MAJOR)
+		if (dev == NULL || major(dev) != dr->dr_major)
+			goto nomatch;
+
+	return (1);
+
+nomatch:
+	return (0);
+}
+
+/*
+ * Determine whether dk matches de on account of dr_pathptrn.
+ */
+static int
+devfs_rule_matchpath(struct devfs_krule *dk, struct devfs_dirent *de)
+{
+	struct devfs_rule *dr = &dk->dk_rule;
+	char *pname;
+	dev_t dev;
+	int plen;
+
+	dev = devfs_rule_getdev(de);
+	if (dev != NULL)
+		pname = dev->si_name;
+	/* XXX: Support symlinks (check d_type == DT_LNK here). */
+	else
+		return (0);
+	KASSERT(pname != NULL, ("devfs_rule_matchpath: NULL pname"));
+
+	/*
+	 * XXX: Interpret dr_pathptrn as a real pattern (support '*',
+	 * '?', and perhaps brace expansion).  For now, we only
+	 * support one trailing asterisk.
+	 */
+	plen = strlen(dr->dr_pathptrn);
+	if (dr->dr_pathptrn[plen - 1] == '*') {
+		if (strlen(pname) >= plen - 1 &&
+		    strncmp(dr->dr_pathptrn, pname, plen - 1) == 0)
+			return (1);
+	} else
+		if (strcmp(dr->dr_pathptrn, pname) == 0)
+			return (1);
+	return (0);
+}
+
+/*
+ * Run dk on de.
+ */
+static void
+devfs_rule_run(struct devfs_krule *dk, struct devfs_dirent *de)
+{
+	struct devfs_rule *dr = &dk->dk_rule;
+	struct devfs_ruleset *ds;
+
+	if (dr->dr_iacts & DRA_BACTS) {
+		if (dr->dr_bacts & DRB_HIDE)
+			de->de_flags |= DE_WHITEOUT;
+		if (dr->dr_bacts & DRB_UNHIDE)
+			de->de_flags &= ~DE_WHITEOUT;
+	}
+	if (dr->dr_iacts & DRA_UID)
+		de->de_uid = dr->dr_uid;
+	if (dr->dr_iacts & DRA_GID)
+		de->de_gid = dr->dr_gid;
+	if (dr->dr_iacts & DRA_MODE)
+		de->de_mode = dr->dr_mode;
+	if (dr->dr_iacts & DRA_INCSET) {
+		ds = devfs_ruleset_bynum(dk->dk_rule.dr_incset);
+		KASSERT(ds != NULL, ("DRA_INCSET but bad dr_incset"));
+		if (dk->dk_ruleset == ds) {
+			/* XXX: Do a better job of detecting loops. */
+			printf("Warning: Ruleset %d including itself!\n",
+			    dk->dk_ruleset->ds_number);
+		} else
+			devfs_ruleset_applyde(ds, de);
+	}
+}
+
+/*
+ * Apply all the rules in ds to de.
+ */
+static void
+devfs_ruleset_applyde(struct devfs_ruleset *ds, struct devfs_dirent *de)
+{
+	struct devfs_krule *dk;
+
+	SLIST_FOREACH(dk, &ds->ds_rules, dk_list) {
+		devfs_rule_applyde(dk, de);
+	}
+}
+
+/*
+ * Apply all the rules in ds to all the entires in dm.
+ */
+static void
+devfs_ruleset_applydm(struct devfs_ruleset *ds, struct devfs_mount *dm)
+{
+	struct devfs_krule *dk;
+
+	/*
+	 * XXX: Does it matter whether we do
+	 *
+	 *	foreach(dk in ds)
+	 *		foreach(de in dm)
+	 *			apply(dk to de)
+	 *
+	 * as opposed to
+	 *
+	 *	foreach(de in dm)
+	 *		foreach(dk in ds)
+	 *			apply(dk to de)
+	 *
+	 * The end result is obviously the same, but does the order
+	 * matter?
+	 */
+	SLIST_FOREACH(dk, &ds->ds_rules, dk_list) {
+		devfs_rule_applydm(dk, dm);
+	}
+}
+
+/*
+ * Find a ruleset by number.
+ */
+static struct devfs_ruleset *
+devfs_ruleset_bynum(devfs_rsnum rsnum)
+{
+	struct devfs_ruleset *ds;
+
+	SLIST_FOREACH(ds, &devfs_rulesets, ds_list) {
+		if (ds->ds_number == rsnum)
+			return (ds);
+	}
+	return (NULL);
+}
+
+/*
+ * Create a new ruleset.
+ */
+static struct devfs_ruleset *
+devfs_ruleset_create(devfs_rsnum rsnum)
+{
+	struct devfs_ruleset *s1, *s2;
+	struct devfs_ruleset *ds;
+
+	KASSERT(devfs_ruleset_bynum(rsnum) == NULL,
+	    ("creating already existent ruleset %d", rsnum));
+
+	ds = malloc(sizeof(*ds), M_DEVFS, M_WAITOK | M_ZERO);
+	ds->ds_number = rsnum;
+	ds->ds_refcount = ds->ds_flags = 0;
+	SLIST_INIT(&ds->ds_rules);
+
+	s1 = SLIST_FIRST(&devfs_rulesets);
+	if (s1 == NULL || s1->ds_number > rsnum)
+		SLIST_INSERT_HEAD(&devfs_rulesets, ds, ds_list);
+	else {
+		SLIST_FOREACH(s1, &devfs_rulesets, ds_list) {
+			s2 = SLIST_NEXT(s1, ds_list);
+			if (s2 == NULL || s2->ds_number > rsnum) {
+				SLIST_INSERT_AFTER(s1, ds, ds_list);
+				break;
+			}
+		}
+	}
+
+	return (ds);
+}
+
+/*
+ * Remove a ruleset form the system.  The ruleset specified must be
+ * empty and not in use.
+ */
+static void
+devfs_ruleset_destroy(struct devfs_ruleset **dsp)
+{
+	struct devfs_ruleset *ds = *dsp;
+
+	KASSERT(SLIST_EMPTY(&ds->ds_rules), ("destroying non-empty ruleset"));
+	KASSERT(ds->ds_refcount == 0, ("destroying busy ruleset"));
+	KASSERT((ds->ds_flags & DS_IMMUTABLE) == 0,
+	    ("destroying immutable ruleset"));
+
+	SLIST_REMOVE(&devfs_rulesets, ds, devfs_ruleset, ds_list);
+	free(ds, M_DEVFS);
+	*dsp = NULL;
+}
+
+/*
+ * Remove a ruleset from the system if it's empty and not used
+ * anywhere.  This should be called after every time a rule is deleted
+ * from this ruleset or the reference count is decremented.
+ */
+static void
+devfs_ruleset_reap(struct devfs_ruleset **dsp)
+{
+	struct devfs_ruleset *ds = *dsp;
+
+	if (SLIST_EMPTY(&ds->ds_rules) && ds->ds_refcount == 0) {
+		devfs_ruleset_destroy(&ds);
+		*dsp = ds;
+	}
+}
+
+/*
+ * Make rsnum the active ruleset for dm.
+ */
+static int
+devfs_ruleset_use(devfs_rsnum rsnum, struct devfs_mount *dm)
+{
+	struct devfs_ruleset *cds, *ds;
+
+	ds = devfs_ruleset_bynum(rsnum);
+	if (ds == NULL)
+		ds = devfs_ruleset_create(rsnum);
+	cds = devfs_ruleset_bynum(dm->dm_ruleset);
+	KASSERT(cds != NULL, ("mount-point has NULL ruleset"));
+
+	/* These should probably be made atomic somehow. */
+	--cds->ds_refcount;
+	++ds->ds_refcount;
+	dm->dm_ruleset = rsnum;
+
+	devfs_ruleset_reap(&cds);
+	return (0);
+}
+
+#endif /* !NODEVFS */
diff --git a/sys/fs/devfs/devfs_vfsops.c b/sys/fs/devfs/devfs_vfsops.c
index 4b2d7701be602..a46b0c4c49a69 100644
--- a/sys/fs/devfs/devfs_vfsops.c
+++ b/sys/fs/devfs/devfs_vfsops.c
@@ -91,6 +91,7 @@ devfs_mount(mp, ndp, td)
 	fmp->dm_rootdir = devfs_vmkdir("(root)", 6, NULL);
 	fmp->dm_rootdir->de_inode = 2;
 	fmp->dm_basedir = fmp->dm_rootdir;
+	devfs_rules_newmount(fmp, td);
 
 	error = devfs_root(mp, &rvp);
 	if (error) {
diff --git a/sys/fs/devfs/devfs_vnops.c b/sys/fs/devfs/devfs_vnops.c
index 8779c96381f77..069d22469166f 100644
--- a/sys/fs/devfs/devfs_vnops.c
+++ b/sys/fs/devfs/devfs_vnops.c
@@ -62,6 +62,7 @@
 
 static int	devfs_access(struct vop_access_args *ap);
 static int	devfs_getattr(struct vop_getattr_args *ap);
+static int	devfs_ioctl(struct vop_ioctl_args *ap);
 static int	devfs_lookupx(struct vop_lookup_args *ap);
 static int	devfs_mknod(struct vop_mknod_args *ap);
 static int	devfs_pathconf(struct vop_pathconf_args *ap);
@@ -247,6 +248,24 @@ devfs_getattr(ap)
 }
 
 static int
+devfs_ioctl(ap)
+	struct vop_ioctl_args /* {
+		struct vnode *a_vp;
+		int  a_command;
+		caddr_t  a_data;
+		int  a_fflag;
+		struct ucred *a_cred;
+		struct thread *a_td;
+	} */ *ap;
+{
+	int error;
+
+	error = devfs_rules_ioctl(ap->a_vp->v_mount, ap->a_command, ap->a_data,
+	    ap->a_td);
+	return (error);
+}
+
+static int
 devfs_lookupx(ap)
 	struct vop_lookup_args /* {
 		struct vnode * a_dvp;
@@ -808,6 +827,7 @@ static struct vnodeopv_entry_desc devfs_vnodeop_entries[] = {
 	{ &vop_default_desc,		(vop_t *) vop_defaultop },
 	{ &vop_access_desc,		(vop_t *) devfs_access },
 	{ &vop_getattr_desc,		(vop_t *) devfs_getattr },
+	{ &vop_ioctl_desc,		(vop_t *) devfs_ioctl },
 	{ &vop_islocked_desc,		(vop_t *) vop_stdislocked },
 	{ &vop_lock_desc,		(vop_t *) vop_stdlock },
 	{ &vop_lookup_desc,		(vop_t *) devfs_lookup },