diff --git a/sys/kern/kern_jail.c b/sys/kern/kern_jail.c
index 4893e4df2781..757b8bd06b89 100644
--- a/sys/kern/kern_jail.c
+++ b/sys/kern/kern_jail.c
@@ -1,4407 +1,4442 @@
 /*-
  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
  *
  * Copyright (c) 1999 Poul-Henning Kamp.
  * Copyright (c) 2008 Bjoern A. Zeeb.
  * Copyright (c) 2009 James Gritton.
  * 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.
  */
 
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
 #include "opt_ddb.h"
 #include "opt_inet.h"
 #include "opt_inet6.h"
 
 #include <sys/param.h>
 #include <sys/types.h>
 #include <sys/kernel.h>
 #include <sys/systm.h>
 #include <sys/errno.h>
 #include <sys/sysproto.h>
 #include <sys/malloc.h>
 #include <sys/osd.h>
 #include <sys/priv.h>
 #include <sys/proc.h>
 #include <sys/taskqueue.h>
 #include <sys/fcntl.h>
 #include <sys/jail.h>
 #include <sys/linker.h>
 #include <sys/lock.h>
 #include <sys/mutex.h>
 #include <sys/racct.h>
 #include <sys/rctl.h>
 #include <sys/refcount.h>
 #include <sys/sx.h>
 #include <sys/sysent.h>
 #include <sys/namei.h>
 #include <sys/mount.h>
 #include <sys/queue.h>
 #include <sys/socket.h>
 #include <sys/syscallsubr.h>
 #include <sys/sysctl.h>
 #include <sys/uuid.h>
 #include <sys/vnode.h>
 
 #include <net/if.h>
 #include <net/vnet.h>
 
 #include <netinet/in.h>
 
 #ifdef DDB
 #include <ddb/ddb.h>
 #endif /* DDB */
 
 #include <security/mac/mac_framework.h>
 
 #define	DEFAULT_HOSTUUID	"00000000-0000-0000-0000-000000000000"
 #define	PRISON0_HOSTUUID_MODULE	"hostuuid"
 
 MALLOC_DEFINE(M_PRISON, "prison", "Prison structures");
 static MALLOC_DEFINE(M_PRISON_RACCT, "prison_racct", "Prison racct structures");
 
 /* Keep struct prison prison0 and some code in kern_jail_set() readable. */
 #ifdef INET
 #ifdef INET6
 #define	_PR_IP_SADDRSEL	PR_IP4_SADDRSEL|PR_IP6_SADDRSEL
 #else
 #define	_PR_IP_SADDRSEL	PR_IP4_SADDRSEL
 #endif
 #else /* !INET */
 #ifdef INET6
 #define	_PR_IP_SADDRSEL	PR_IP6_SADDRSEL
 #else
 #define	_PR_IP_SADDRSEL	0
 #endif
 #endif
 
 /* prison0 describes what is "real" about the system. */
 struct prison prison0 = {
 	.pr_id		= 0,
 	.pr_name	= "0",
 	.pr_ref		= 1,
 	.pr_uref	= 1,
 	.pr_path	= "/",
 	.pr_securelevel	= -1,
 	.pr_devfs_rsnum = 0,
 	.pr_childmax	= JAIL_MAX,
 	.pr_hostuuid	= DEFAULT_HOSTUUID,
 	.pr_children	= LIST_HEAD_INITIALIZER(prison0.pr_children),
 #ifdef VIMAGE
 	.pr_flags	= PR_HOST|PR_VNET|_PR_IP_SADDRSEL,
 #else
 	.pr_flags	= PR_HOST|_PR_IP_SADDRSEL,
 #endif
 	.pr_allow	= PR_ALLOW_ALL_STATIC,
 };
 MTX_SYSINIT(prison0, &prison0.pr_mtx, "jail mutex", MTX_DEF);
 
 struct bool_flags {
 	const char	*name;
 	const char	*noname;
 	volatile u_int	 flag;
 };
 struct jailsys_flags {
 	const char	*name;
 	unsigned	 disable;
 	unsigned	 new;
 };
 
 /* allprison, allprison_racct and lastprid are protected by allprison_lock. */
 struct	sx allprison_lock;
 SX_SYSINIT(allprison_lock, &allprison_lock, "allprison");
 struct	prisonlist allprison = TAILQ_HEAD_INITIALIZER(allprison);
 LIST_HEAD(, prison_racct) allprison_racct;
 int	lastprid = 0;
 
 static int get_next_prid(struct prison **insprp);
 static int do_jail_attach(struct thread *td, struct prison *pr);
 static void prison_complete(void *context, int pending);
 static void prison_deref(struct prison *pr, int flags);
 static void prison_set_allow_locked(struct prison *pr, unsigned flag,
     int enable);
 static char *prison_path(struct prison *pr1, struct prison *pr2);
 static void prison_remove_one(struct prison *pr);
 #ifdef RACCT
 static void prison_racct_attach(struct prison *pr);
 static void prison_racct_modify(struct prison *pr);
 static void prison_racct_detach(struct prison *pr);
 #endif
 
 /* Flags for prison_deref */
 #define	PD_DEREF	0x01	/* Decrement pr_ref */
 #define	PD_DEUREF	0x02	/* Decrement pr_uref */
 #define	PD_LOCKED	0x04	/* pr_mtx is held */
 #define	PD_LIST_SLOCKED	0x08	/* allprison_lock is held shared */
 #define	PD_LIST_XLOCKED	0x10	/* allprison_lock is held exclusive */
 
 /*
  * Parameter names corresponding to PR_* flag values.  Size values are for kvm
  * as we cannot figure out the size of a sparse array, or an array without a
  * terminating entry.
  */
 static struct bool_flags pr_flag_bool[] = {
 	{"persist", "nopersist", PR_PERSIST},
 #ifdef INET
 	{"ip4.saddrsel", "ip4.nosaddrsel", PR_IP4_SADDRSEL},
 #endif
 #ifdef INET6
 	{"ip6.saddrsel", "ip6.nosaddrsel", PR_IP6_SADDRSEL},
 #endif
 };
 const size_t pr_flag_bool_size = sizeof(pr_flag_bool);
 
 static struct jailsys_flags pr_flag_jailsys[] = {
 	{"host", 0, PR_HOST},
 #ifdef VIMAGE
 	{"vnet", 0, PR_VNET},
 #endif
 #ifdef INET
 	{"ip4", PR_IP4_USER, PR_IP4_USER},
 #endif
 #ifdef INET6
 	{"ip6", PR_IP6_USER, PR_IP6_USER},
 #endif
 };
 const size_t pr_flag_jailsys_size = sizeof(pr_flag_jailsys);
 
 /*
  * Make this array full-size so dynamic parameters can be added.
  * It is protected by prison0.mtx, but lockless reading is allowed
  * with an atomic check of the flag values.
  */
 static struct bool_flags pr_flag_allow[NBBY * NBPW] = {
 	{"allow.set_hostname", "allow.noset_hostname", PR_ALLOW_SET_HOSTNAME},
 	{"allow.sysvipc", "allow.nosysvipc", PR_ALLOW_SYSVIPC},
 	{"allow.raw_sockets", "allow.noraw_sockets", PR_ALLOW_RAW_SOCKETS},
 	{"allow.chflags", "allow.nochflags", PR_ALLOW_CHFLAGS},
 	{"allow.mount", "allow.nomount", PR_ALLOW_MOUNT},
 	{"allow.quotas", "allow.noquotas", PR_ALLOW_QUOTAS},
 	{"allow.socket_af", "allow.nosocket_af", PR_ALLOW_SOCKET_AF},
 	{"allow.mlock", "allow.nomlock", PR_ALLOW_MLOCK},
 	{"allow.reserved_ports", "allow.noreserved_ports",
 	 PR_ALLOW_RESERVED_PORTS},
 	{"allow.read_msgbuf", "allow.noread_msgbuf", PR_ALLOW_READ_MSGBUF},
 	{"allow.unprivileged_proc_debug", "allow.nounprivileged_proc_debug",
 	 PR_ALLOW_UNPRIV_DEBUG},
 	{"allow.suser", "allow.nosuser", PR_ALLOW_SUSER},
 };
 static unsigned pr_allow_all = PR_ALLOW_ALL_STATIC;
 const size_t pr_flag_allow_size = sizeof(pr_flag_allow);
 
 #define	JAIL_DEFAULT_ALLOW		(PR_ALLOW_SET_HOSTNAME | \
 					 PR_ALLOW_RESERVED_PORTS | \
 					 PR_ALLOW_UNPRIV_DEBUG | \
 					 PR_ALLOW_SUSER)
 #define	JAIL_DEFAULT_ENFORCE_STATFS	2
 #define	JAIL_DEFAULT_DEVFS_RSNUM	0
 static unsigned jail_default_allow = JAIL_DEFAULT_ALLOW;
 static int jail_default_enforce_statfs = JAIL_DEFAULT_ENFORCE_STATFS;
 static int jail_default_devfs_rsnum = JAIL_DEFAULT_DEVFS_RSNUM;
 #if defined(INET) || defined(INET6)
 static unsigned jail_max_af_ips = 255;
 #endif
 
 /*
  * Initialize the parts of prison0 that can't be static-initialized with
  * constants.  This is called from proc0_init() after creating thread0 cpuset.
  */
 void
 prison0_init(void)
 {
 	uint8_t *file, *data;
 	size_t size;
 
 	prison0.pr_cpuset = cpuset_ref(thread0.td_cpuset);
 	prison0.pr_osreldate = osreldate;
 	strlcpy(prison0.pr_osrelease, osrelease, sizeof(prison0.pr_osrelease));
 
 	/* If we have a preloaded hostuuid, use it. */
 	file = preload_search_by_type(PRISON0_HOSTUUID_MODULE);
 	if (file != NULL) {
 		data = preload_fetch_addr(file);
 		size = preload_fetch_size(file);
 		if (data != NULL) {
 			/*
 			 * The preloaded data may include trailing whitespace, almost
 			 * certainly a newline; skip over any whitespace or
 			 * non-printable characters to be safe.
 			 */
 			while (size > 0 && data[size - 1] <= 0x20) {
 				data[size--] = '\0';
 			}
 			if (validate_uuid(data, size, NULL, 0) == 0) {
 				(void)strlcpy(prison0.pr_hostuuid, data,
 				    size + 1);
 			} else if (bootverbose) {
 				printf("hostuuid: preload data malformed: '%s'",
 				    data);
 			}
 		}
 	}
 	if (bootverbose)
 		printf("hostuuid: using %s\n", prison0.pr_hostuuid);
 }
 
 /*
  * struct jail_args {
  *	struct jail *jail;
  * };
  */
 int
 sys_jail(struct thread *td, struct jail_args *uap)
 {
 	uint32_t version;
 	int error;
 	struct jail j;
 
 	error = copyin(uap->jail, &version, sizeof(uint32_t));
 	if (error)
 		return (error);
 
 	switch (version) {
 	case 0:
 	{
 		struct jail_v0 j0;
 
 		/* FreeBSD single IPv4 jails. */
 		bzero(&j, sizeof(struct jail));
 		error = copyin(uap->jail, &j0, sizeof(struct jail_v0));
 		if (error)
 			return (error);
 		j.version = j0.version;
 		j.path = j0.path;
 		j.hostname = j0.hostname;
 		j.ip4s = htonl(j0.ip_number);	/* jail_v0 is host order */
 		break;
 	}
 
 	case 1:
 		/*
 		 * Version 1 was used by multi-IPv4 jail implementations
 		 * that never made it into the official kernel.
 		 */
 		return (EINVAL);
 
 	case 2:	/* JAIL_API_VERSION */
 		/* FreeBSD multi-IPv4/IPv6,noIP jails. */
 		error = copyin(uap->jail, &j, sizeof(struct jail));
 		if (error)
 			return (error);
 		break;
 
 	default:
 		/* Sci-Fi jails are not supported, sorry. */
 		return (EINVAL);
 	}
 	return (kern_jail(td, &j));
 }
 
 int
 kern_jail(struct thread *td, struct jail *j)
 {
 	struct iovec optiov[2 * (4 + nitems(pr_flag_allow)
 #ifdef INET
 			    + 1
 #endif
 #ifdef INET6
 			    + 1
 #endif
 			    )];
 	struct uio opt;
 	char *u_path, *u_hostname, *u_name;
 	struct bool_flags *bf;
 #ifdef INET
 	uint32_t ip4s;
 	struct in_addr *u_ip4;
 #endif
 #ifdef INET6
 	struct in6_addr *u_ip6;
 #endif
 	size_t tmplen;
 	int error, enforce_statfs;
 
 	bzero(&optiov, sizeof(optiov));
 	opt.uio_iov = optiov;
 	opt.uio_iovcnt = 0;
 	opt.uio_offset = -1;
 	opt.uio_resid = -1;
 	opt.uio_segflg = UIO_SYSSPACE;
 	opt.uio_rw = UIO_READ;
 	opt.uio_td = td;
 
 	/* Set permissions for top-level jails from sysctls. */
 	if (!jailed(td->td_ucred)) {
 		for (bf = pr_flag_allow;
 		     bf < pr_flag_allow + nitems(pr_flag_allow) &&
 			atomic_load_int(&bf->flag) != 0;
 		     bf++) {
 			optiov[opt.uio_iovcnt].iov_base = __DECONST(char *,
 			    (jail_default_allow & bf->flag)
 			    ? bf->name : bf->noname);
 			optiov[opt.uio_iovcnt].iov_len =
 			    strlen(optiov[opt.uio_iovcnt].iov_base) + 1;
 			opt.uio_iovcnt += 2;
 		}
 		optiov[opt.uio_iovcnt].iov_base = "enforce_statfs";
 		optiov[opt.uio_iovcnt].iov_len = sizeof("enforce_statfs");
 		opt.uio_iovcnt++;
 		enforce_statfs = jail_default_enforce_statfs;
 		optiov[opt.uio_iovcnt].iov_base = &enforce_statfs;
 		optiov[opt.uio_iovcnt].iov_len = sizeof(enforce_statfs);
 		opt.uio_iovcnt++;
 	}
 
 	tmplen = MAXPATHLEN + MAXHOSTNAMELEN + MAXHOSTNAMELEN;
 #ifdef INET
 	ip4s = (j->version == 0) ? 1 : j->ip4s;
 	if (ip4s > jail_max_af_ips)
 		return (EINVAL);
 	tmplen += ip4s * sizeof(struct in_addr);
 #else
 	if (j->ip4s > 0)
 		return (EINVAL);
 #endif
 #ifdef INET6
 	if (j->ip6s > jail_max_af_ips)
 		return (EINVAL);
 	tmplen += j->ip6s * sizeof(struct in6_addr);
 #else
 	if (j->ip6s > 0)
 		return (EINVAL);
 #endif
 	u_path = malloc(tmplen, M_TEMP, M_WAITOK);
 	u_hostname = u_path + MAXPATHLEN;
 	u_name = u_hostname + MAXHOSTNAMELEN;
 #ifdef INET
 	u_ip4 = (struct in_addr *)(u_name + MAXHOSTNAMELEN);
 #endif
 #ifdef INET6
 #ifdef INET
 	u_ip6 = (struct in6_addr *)(u_ip4 + ip4s);
 #else
 	u_ip6 = (struct in6_addr *)(u_name + MAXHOSTNAMELEN);
 #endif
 #endif
 	optiov[opt.uio_iovcnt].iov_base = "path";
 	optiov[opt.uio_iovcnt].iov_len = sizeof("path");
 	opt.uio_iovcnt++;
 	optiov[opt.uio_iovcnt].iov_base = u_path;
 	error = copyinstr(j->path, u_path, MAXPATHLEN,
 	    &optiov[opt.uio_iovcnt].iov_len);
 	if (error) {
 		free(u_path, M_TEMP);
 		return (error);
 	}
 	opt.uio_iovcnt++;
 	optiov[opt.uio_iovcnt].iov_base = "host.hostname";
 	optiov[opt.uio_iovcnt].iov_len = sizeof("host.hostname");
 	opt.uio_iovcnt++;
 	optiov[opt.uio_iovcnt].iov_base = u_hostname;
 	error = copyinstr(j->hostname, u_hostname, MAXHOSTNAMELEN,
 	    &optiov[opt.uio_iovcnt].iov_len);
 	if (error) {
 		free(u_path, M_TEMP);
 		return (error);
 	}
 	opt.uio_iovcnt++;
 	if (j->jailname != NULL) {
 		optiov[opt.uio_iovcnt].iov_base = "name";
 		optiov[opt.uio_iovcnt].iov_len = sizeof("name");
 		opt.uio_iovcnt++;
 		optiov[opt.uio_iovcnt].iov_base = u_name;
 		error = copyinstr(j->jailname, u_name, MAXHOSTNAMELEN,
 		    &optiov[opt.uio_iovcnt].iov_len);
 		if (error) {
 			free(u_path, M_TEMP);
 			return (error);
 		}
 		opt.uio_iovcnt++;
 	}
 #ifdef INET
 	optiov[opt.uio_iovcnt].iov_base = "ip4.addr";
 	optiov[opt.uio_iovcnt].iov_len = sizeof("ip4.addr");
 	opt.uio_iovcnt++;
 	optiov[opt.uio_iovcnt].iov_base = u_ip4;
 	optiov[opt.uio_iovcnt].iov_len = ip4s * sizeof(struct in_addr);
 	if (j->version == 0)
 		u_ip4->s_addr = j->ip4s;
 	else {
 		error = copyin(j->ip4, u_ip4, optiov[opt.uio_iovcnt].iov_len);
 		if (error) {
 			free(u_path, M_TEMP);
 			return (error);
 		}
 	}
 	opt.uio_iovcnt++;
 #endif
 #ifdef INET6
 	optiov[opt.uio_iovcnt].iov_base = "ip6.addr";
 	optiov[opt.uio_iovcnt].iov_len = sizeof("ip6.addr");
 	opt.uio_iovcnt++;
 	optiov[opt.uio_iovcnt].iov_base = u_ip6;
 	optiov[opt.uio_iovcnt].iov_len = j->ip6s * sizeof(struct in6_addr);
 	error = copyin(j->ip6, u_ip6, optiov[opt.uio_iovcnt].iov_len);
 	if (error) {
 		free(u_path, M_TEMP);
 		return (error);
 	}
 	opt.uio_iovcnt++;
 #endif
 	KASSERT(opt.uio_iovcnt <= nitems(optiov),
 		("kern_jail: too many iovecs (%d)", opt.uio_iovcnt));
 	error = kern_jail_set(td, &opt, JAIL_CREATE | JAIL_ATTACH);
 	free(u_path, M_TEMP);
 	return (error);
 }
 
 /*
  * struct jail_set_args {
  *	struct iovec *iovp;
  *	unsigned int iovcnt;
  *	int flags;
  * };
  */
 int
 sys_jail_set(struct thread *td, struct jail_set_args *uap)
 {
 	struct uio *auio;
 	int error;
 
 	/* Check that we have an even number of iovecs. */
 	if (uap->iovcnt & 1)
 		return (EINVAL);
 
 	error = copyinuio(uap->iovp, uap->iovcnt, &auio);
 	if (error)
 		return (error);
 	error = kern_jail_set(td, auio, uap->flags);
 	free(auio, M_IOV);
 	return (error);
 }
 
 int
 kern_jail_set(struct thread *td, struct uio *optuio, int flags)
 {
 	struct nameidata nd;
 #ifdef INET
 	struct in_addr *ip4;
 #endif
 #ifdef INET6
 	struct in6_addr *ip6;
 #endif
 	struct vfsopt *opt;
 	struct vfsoptlist *opts;
 	struct prison *pr, *deadpr, *inspr, *mypr, *ppr, *tpr;
 	struct vnode *root;
 	char *domain, *errmsg, *host, *name, *namelc, *p, *path, *uuid;
 	char *g_path, *osrelstr;
 	struct bool_flags *bf;
 	struct jailsys_flags *jsf;
 #if defined(INET) || defined(INET6)
 	struct prison *tppr;
 	void *op;
 #endif
 	unsigned long hid;
 	size_t namelen, onamelen, pnamelen;
 	int born, created, cuflags, descend, drflags, enforce;
 	int error, errmsg_len, errmsg_pos;
 	int gotchildmax, gotenforce, gothid, gotrsnum, gotslevel;
 	int jid, jsys, len, level;
 	int childmax, osreldt, rsnum, slevel;
 #if defined(INET) || defined(INET6)
 	int ii, ij;
 #endif
 #ifdef INET
 	int ip4s, redo_ip4;
 #endif
 #ifdef INET6
 	int ip6s, redo_ip6;
 #endif
 	uint64_t pr_allow, ch_allow, pr_flags, ch_flags;
 	uint64_t pr_allow_diff;
 	unsigned tallow;
 	char numbuf[12];
 
 	error = priv_check(td, PRIV_JAIL_SET);
 	if (!error && (flags & JAIL_ATTACH))
 		error = priv_check(td, PRIV_JAIL_ATTACH);
 	if (error)
 		return (error);
 	mypr = td->td_ucred->cr_prison;
 	if ((flags & JAIL_CREATE) && mypr->pr_childmax == 0)
 		return (EPERM);
 	if (flags & ~JAIL_SET_MASK)
 		return (EINVAL);
 
 	/*
 	 * Check all the parameters before committing to anything.  Not all
 	 * errors can be caught early, but we may as well try.  Also, this
 	 * takes care of some expensive stuff (path lookup) before getting
 	 * the allprison lock.
 	 *
 	 * XXX Jails are not filesystems, and jail parameters are not mount
 	 *     options.  But it makes more sense to re-use the vfsopt code
 	 *     than duplicate it under a different name.
 	 */
 	error = vfs_buildopts(optuio, &opts);
 	if (error)
 		return (error);
 #ifdef INET
 	ip4 = NULL;
 #endif
 #ifdef INET6
 	ip6 = NULL;
 #endif
 	g_path = NULL;
 
 	cuflags = flags & (JAIL_CREATE | JAIL_UPDATE);
 	if (!cuflags) {
 		error = EINVAL;
 		vfs_opterror(opts, "no valid operation (create or update)");
 		goto done_errmsg;
 	}
 
 	error = vfs_copyopt(opts, "jid", &jid, sizeof(jid));
 	if (error == ENOENT)
 		jid = 0;
 	else if (error != 0)
 		goto done_free;
 
 	error = vfs_copyopt(opts, "securelevel", &slevel, sizeof(slevel));
 	if (error == ENOENT)
 		gotslevel = 0;
 	else if (error != 0)
 		goto done_free;
 	else
 		gotslevel = 1;
 
 	error =
 	    vfs_copyopt(opts, "children.max", &childmax, sizeof(childmax));
 	if (error == ENOENT)
 		gotchildmax = 0;
 	else if (error != 0)
 		goto done_free;
 	else
 		gotchildmax = 1;
 
 	error = vfs_copyopt(opts, "enforce_statfs", &enforce, sizeof(enforce));
 	if (error == ENOENT)
 		gotenforce = 0;
 	else if (error != 0)
 		goto done_free;
 	else if (enforce < 0 || enforce > 2) {
 		error = EINVAL;
 		goto done_free;
 	} else
 		gotenforce = 1;
 
 	error = vfs_copyopt(opts, "devfs_ruleset", &rsnum, sizeof(rsnum));
 	if (error == ENOENT)
 		gotrsnum = 0;
 	else if (error != 0)
 		goto done_free;
 	else
 		gotrsnum = 1;
 
 	pr_flags = ch_flags = 0;
 	for (bf = pr_flag_bool;
 	     bf < pr_flag_bool + nitems(pr_flag_bool);
 	     bf++) {
 		vfs_flagopt(opts, bf->name, &pr_flags, bf->flag);
 		vfs_flagopt(opts, bf->noname, &ch_flags, bf->flag);
 	}
 	ch_flags |= pr_flags;
 	for (jsf = pr_flag_jailsys;
 	     jsf < pr_flag_jailsys + nitems(pr_flag_jailsys);
 	     jsf++) {
 		error = vfs_copyopt(opts, jsf->name, &jsys, sizeof(jsys));
 		if (error == ENOENT)
 			continue;
 		if (error != 0)
 			goto done_free;
 		switch (jsys) {
 		case JAIL_SYS_DISABLE:
 			if (!jsf->disable) {
 				error = EINVAL;
 				goto done_free;
 			}
 			pr_flags |= jsf->disable;
 			break;
 		case JAIL_SYS_NEW:
 			pr_flags |= jsf->new;
 			break;
 		case JAIL_SYS_INHERIT:
 			break;
 		default:
 			error = EINVAL;
 			goto done_free;
 		}
 		ch_flags |= jsf->new | jsf->disable;
 	}
 	if ((flags & (JAIL_CREATE | JAIL_UPDATE | JAIL_ATTACH)) == JAIL_CREATE
 	    && !(pr_flags & PR_PERSIST)) {
 		error = EINVAL;
 		vfs_opterror(opts, "new jail must persist or attach");
 		goto done_errmsg;
 	}
 #ifdef VIMAGE
 	if ((flags & JAIL_UPDATE) && (ch_flags & PR_VNET)) {
 		error = EINVAL;
 		vfs_opterror(opts, "vnet cannot be changed after creation");
 		goto done_errmsg;
 	}
 #endif
 #ifdef INET
 	if ((flags & JAIL_UPDATE) && (ch_flags & PR_IP4_USER)) {
 		error = EINVAL;
 		vfs_opterror(opts, "ip4 cannot be changed after creation");
 		goto done_errmsg;
 	}
 #endif
 #ifdef INET6
 	if ((flags & JAIL_UPDATE) && (ch_flags & PR_IP6_USER)) {
 		error = EINVAL;
 		vfs_opterror(opts, "ip6 cannot be changed after creation");
 		goto done_errmsg;
 	}
 #endif
 
 	pr_allow = ch_allow = 0;
 	for (bf = pr_flag_allow;
 	     bf < pr_flag_allow + nitems(pr_flag_allow) &&
 		atomic_load_int(&bf->flag) != 0;
 	     bf++) {
 		vfs_flagopt(opts, bf->name, &pr_allow, bf->flag);
 		vfs_flagopt(opts, bf->noname, &ch_allow, bf->flag);
 	}
 	ch_allow |= pr_allow;
 
 	error = vfs_getopt(opts, "name", (void **)&name, &len);
 	if (error == ENOENT)
 		name = NULL;
 	else if (error != 0)
 		goto done_free;
 	else {
 		if (len == 0 || name[len - 1] != '\0') {
 			error = EINVAL;
 			goto done_free;
 		}
 		if (len > MAXHOSTNAMELEN) {
 			error = ENAMETOOLONG;
 			goto done_free;
 		}
 	}
 
 	error = vfs_getopt(opts, "host.hostname", (void **)&host, &len);
 	if (error == ENOENT)
 		host = NULL;
 	else if (error != 0)
 		goto done_free;
 	else {
 		ch_flags |= PR_HOST;
 		pr_flags |= PR_HOST;
 		if (len == 0 || host[len - 1] != '\0') {
 			error = EINVAL;
 			goto done_free;
 		}
 		if (len > MAXHOSTNAMELEN) {
 			error = ENAMETOOLONG;
 			goto done_free;
 		}
 	}
 
 	error = vfs_getopt(opts, "host.domainname", (void **)&domain, &len);
 	if (error == ENOENT)
 		domain = NULL;
 	else if (error != 0)
 		goto done_free;
 	else {
 		ch_flags |= PR_HOST;
 		pr_flags |= PR_HOST;
 		if (len == 0 || domain[len - 1] != '\0') {
 			error = EINVAL;
 			goto done_free;
 		}
 		if (len > MAXHOSTNAMELEN) {
 			error = ENAMETOOLONG;
 			goto done_free;
 		}
 	}
 
 	error = vfs_getopt(opts, "host.hostuuid", (void **)&uuid, &len);
 	if (error == ENOENT)
 		uuid = NULL;
 	else if (error != 0)
 		goto done_free;
 	else {
 		ch_flags |= PR_HOST;
 		pr_flags |= PR_HOST;
 		if (len == 0 || uuid[len - 1] != '\0') {
 			error = EINVAL;
 			goto done_free;
 		}
 		if (len > HOSTUUIDLEN) {
 			error = ENAMETOOLONG;
 			goto done_free;
 		}
 	}
 
 #ifdef COMPAT_FREEBSD32
 	if (SV_PROC_FLAG(td->td_proc, SV_ILP32)) {
 		uint32_t hid32;
 
 		error = vfs_copyopt(opts, "host.hostid", &hid32, sizeof(hid32));
 		hid = hid32;
 	} else
 #endif
 		error = vfs_copyopt(opts, "host.hostid", &hid, sizeof(hid));
 	if (error == ENOENT)
 		gothid = 0;
 	else if (error != 0)
 		goto done_free;
 	else {
 		gothid = 1;
 		ch_flags |= PR_HOST;
 		pr_flags |= PR_HOST;
 	}
 
 #ifdef INET
 	error = vfs_getopt(opts, "ip4.addr", &op, &ip4s);
 	if (error == ENOENT)
 		ip4s = 0;
 	else if (error != 0)
 		goto done_free;
 	else if (ip4s & (sizeof(*ip4) - 1)) {
 		error = EINVAL;
 		goto done_free;
 	} else {
 		ch_flags |= PR_IP4_USER;
 		pr_flags |= PR_IP4_USER;
 		if (ip4s > 0) {
 			ip4s /= sizeof(*ip4);
 			if (ip4s > jail_max_af_ips) {
 				error = EINVAL;
 				vfs_opterror(opts, "too many IPv4 addresses");
 				goto done_errmsg;
 			}
 			ip4 = malloc(ip4s * sizeof(*ip4), M_PRISON, M_WAITOK);
 			bcopy(op, ip4, ip4s * sizeof(*ip4));
 			/*
 			 * IP addresses are all sorted but ip[0] to preserve
 			 * the primary IP address as given from userland.
 			 * This special IP is used for unbound outgoing
 			 * connections as well for "loopback" traffic in case
 			 * source address selection cannot find any more fitting
 			 * address to connect from.
 			 */
 			if (ip4s > 1)
 				qsort(ip4 + 1, ip4s - 1, sizeof(*ip4),
 				    prison_qcmp_v4);
 			/*
 			 * Check for duplicate addresses and do some simple
 			 * zero and broadcast checks. If users give other bogus
 			 * addresses it is their problem.
 			 *
 			 * We do not have to care about byte order for these
 			 * checks so we will do them in NBO.
 			 */
 			for (ii = 0; ii < ip4s; ii++) {
 				if (ip4[ii].s_addr == INADDR_ANY ||
 				    ip4[ii].s_addr == INADDR_BROADCAST) {
 					error = EINVAL;
 					goto done_free;
 				}
 				if ((ii+1) < ip4s &&
 				    (ip4[0].s_addr == ip4[ii+1].s_addr ||
 				     ip4[ii].s_addr == ip4[ii+1].s_addr)) {
 					error = EINVAL;
 					goto done_free;
 				}
 			}
 		}
 	}
 #endif
 
 #ifdef INET6
 	error = vfs_getopt(opts, "ip6.addr", &op, &ip6s);
 	if (error == ENOENT)
 		ip6s = 0;
 	else if (error != 0)
 		goto done_free;
 	else if (ip6s & (sizeof(*ip6) - 1)) {
 		error = EINVAL;
 		goto done_free;
 	} else {
 		ch_flags |= PR_IP6_USER;
 		pr_flags |= PR_IP6_USER;
 		if (ip6s > 0) {
 			ip6s /= sizeof(*ip6);
 			if (ip6s > jail_max_af_ips) {
 				error = EINVAL;
 				vfs_opterror(opts, "too many IPv6 addresses");
 				goto done_errmsg;
 			}
 			ip6 = malloc(ip6s * sizeof(*ip6), M_PRISON, M_WAITOK);
 			bcopy(op, ip6, ip6s * sizeof(*ip6));
 			if (ip6s > 1)
 				qsort(ip6 + 1, ip6s - 1, sizeof(*ip6),
 				    prison_qcmp_v6);
 			for (ii = 0; ii < ip6s; ii++) {
 				if (IN6_IS_ADDR_UNSPECIFIED(&ip6[ii])) {
 					error = EINVAL;
 					goto done_free;
 				}
 				if ((ii+1) < ip6s &&
 				    (IN6_ARE_ADDR_EQUAL(&ip6[0], &ip6[ii+1]) ||
 				     IN6_ARE_ADDR_EQUAL(&ip6[ii], &ip6[ii+1])))
 				{
 					error = EINVAL;
 					goto done_free;
 				}
 			}
 		}
 	}
 #endif
 
 #if defined(VIMAGE) && (defined(INET) || defined(INET6))
 	if ((ch_flags & PR_VNET) && (ch_flags & (PR_IP4_USER | PR_IP6_USER))) {
 		error = EINVAL;
 		vfs_opterror(opts,
 		    "vnet jails cannot have IP address restrictions");
 		goto done_errmsg;
 	}
 #endif
 
 	error = vfs_getopt(opts, "osrelease", (void **)&osrelstr, &len);
 	if (error == ENOENT)
 		osrelstr = NULL;
 	else if (error != 0)
 		goto done_free;
 	else {
 		if (flags & JAIL_UPDATE) {
 			error = EINVAL;
 			vfs_opterror(opts,
 			    "osrelease cannot be changed after creation");
 			goto done_errmsg;
 		}
 		if (len == 0 || osrelstr[len - 1] != '\0') {
 			error = EINVAL;
 			goto done_free;
 		}
 		if (len >= OSRELEASELEN) {
 			error = ENAMETOOLONG;
 			vfs_opterror(opts,
 			    "osrelease string must be 1-%d bytes long",
 			    OSRELEASELEN - 1);
 			goto done_errmsg;
 		}
 	}
 
 	error = vfs_copyopt(opts, "osreldate", &osreldt, sizeof(osreldt));
 	if (error == ENOENT)
 		osreldt = 0;
 	else if (error != 0)
 		goto done_free;
 	else {
 		if (flags & JAIL_UPDATE) {
 			error = EINVAL;
 			vfs_opterror(opts,
 			    "osreldate cannot be changed after creation");
 			goto done_errmsg;
 		}
 		if (osreldt == 0) {
 			error = EINVAL;
 			vfs_opterror(opts, "osreldate cannot be 0");
 			goto done_errmsg;
 		}
 	}
 
 	root = NULL;
 	error = vfs_getopt(opts, "path", (void **)&path, &len);
 	if (error == ENOENT)
 		path = NULL;
 	else if (error != 0)
 		goto done_free;
 	else {
 		if (flags & JAIL_UPDATE) {
 			error = EINVAL;
 			vfs_opterror(opts,
 			    "path cannot be changed after creation");
 			goto done_errmsg;
 		}
 		if (len == 0 || path[len - 1] != '\0') {
 			error = EINVAL;
 			goto done_free;
 		}
 		NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE,
 		    path, td);
 		error = namei(&nd);
 		if (error)
 			goto done_free;
 		root = nd.ni_vp;
 		NDFREE(&nd, NDF_ONLY_PNBUF);
 		g_path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
 		strlcpy(g_path, path, MAXPATHLEN);
 		error = vn_path_to_global_path(td, root, g_path, MAXPATHLEN);
 		if (error == 0) {
 			path = g_path;
 		} else {
 			/* exit on other errors */
 			goto done_free;
 		}
 		if (root->v_type != VDIR) {
 			error = ENOTDIR;
 			vput(root);
 			goto done_free;
 		}
 		VOP_UNLOCK(root);
 	}
 
 	/*
 	 * Find the specified jail, or at least its parent.
 	 * This abuses the file error codes ENOENT and EEXIST.
 	 */
 	pr = NULL;
 	ppr = mypr;
 	inspr = NULL;
 	if (cuflags == JAIL_CREATE && jid == 0 && name != NULL) {
 		namelc = strrchr(name, '.');
 		jid = strtoul(namelc != NULL ? namelc + 1 : name, &p, 10);
 		if (*p != '\0')
 			jid = 0;
 	}
 	sx_xlock(&allprison_lock);
 	drflags = PD_LIST_XLOCKED;
 	if (jid != 0) {
 		if (jid < 0) {
 			error = EINVAL;
 			vfs_opterror(opts, "negative jid");
 			goto done_deref;
 		}
 		/*
 		 * See if a requested jid already exists.  Keep track of
 		 * where it can be inserted later.
 		 */
 		TAILQ_FOREACH(inspr, &allprison, pr_list) {
 			if (inspr->pr_id == jid) {
 				mtx_lock(&inspr->pr_mtx);
 				if (prison_isvalid(inspr)) {
 					pr = inspr;
 					drflags |= PD_LOCKED;
 					inspr = NULL;
 				} else
 					mtx_unlock(&inspr->pr_mtx);
 				break;
 			}
 			if (inspr->pr_id > jid)
 				break;
 		}
 		if (pr != NULL) {
 			ppr = pr->pr_parent;
 			/* Create: jid must not exist. */
 			if (cuflags == JAIL_CREATE) {
 				/*
 				 * Even creators that cannot see the jail will
 				 * get EEXIST.
 				 */
 				error = EEXIST;
 				vfs_opterror(opts, "jail %d already exists",
 				    jid);
 				goto done_deref;
 			}
 			if (!prison_ischild(mypr, pr)) {
 				/*
 				 * Updaters get ENOENT if they cannot see the
 				 * jail.  This is true even for CREATE | UPDATE,
 				 * which normally cannot give this error.
 				 */
 				error = ENOENT;
 				vfs_opterror(opts, "jail %d not found", jid);
 				goto done_deref;
 			} else if (!prison_isalive(pr)) {
 				if (!(flags & JAIL_DYING)) {
 					error = ENOENT;
 					vfs_opterror(opts, "jail %d is dying",
 					    jid);
 					goto done_deref;
 				} else if ((flags & JAIL_ATTACH) ||
 				    (pr_flags & PR_PERSIST)) {
 					/*
 					 * A dying jail might be resurrected
 					 * (via attach or persist), but first
 					 * it must determine if another jail
 					 * has claimed its name.  Accomplish
 					 * this by implicitly re-setting the
 					 * name.
 					 */
 					if (name == NULL)
 						name = prison_name(mypr, pr);
 				}
 			}
 		} else {
 			/* Update: jid must exist. */
 			if (cuflags == JAIL_UPDATE) {
 				error = ENOENT;
 				vfs_opterror(opts, "jail %d not found", jid);
 				goto done_deref;
 			}
 		}
 	}
 	/*
 	 * If the caller provided a name, look for a jail by that name.
 	 * This has different semantics for creates and updates keyed by jid
 	 * (where the name must not already exist in a different jail),
 	 * and updates keyed by the name itself (where the name must exist
 	 * because that is the jail being updated).
 	 */
 	namelc = NULL;
 	if (name != NULL) {
 		namelc = strrchr(name, '.');
 		if (namelc == NULL)
 			namelc = name;
 		else {
 			/*
 			 * This is a hierarchical name.  Split it into the
 			 * parent and child names, and make sure the parent
 			 * exists or matches an already found jail.
 			 */
 			if (pr != NULL) {
 				if (strncmp(name, ppr->pr_name, namelc - name)
 				    || ppr->pr_name[namelc - name] != '\0') {
 					error = EINVAL;
 					vfs_opterror(opts,
 					    "cannot change jail's parent");
 					goto done_deref;
 				}
 			} else {
 				*namelc = '\0';
 				ppr = prison_find_name(mypr, name);
 				if (ppr == NULL) {
 					error = ENOENT;
 					vfs_opterror(opts,
 					    "jail \"%s\" not found", name);
 					goto done_deref;
 				}
 				mtx_unlock(&ppr->pr_mtx);
 				*namelc = '.';
 			}
 			namelc++;
 		}
 		if (namelc[0] != '\0') {
 			pnamelen =
 			    (ppr == &prison0) ? 0 : strlen(ppr->pr_name) + 1;
  name_again:
 			deadpr = NULL;
 			FOREACH_PRISON_CHILD(ppr, tpr) {
 				if (tpr != pr && tpr->pr_ref > 0 &&
 				    !strcmp(tpr->pr_name + pnamelen, namelc)) {
 					mtx_lock(&tpr->pr_mtx);
 					if (prison_isalive(tpr)) {
 						if (pr == NULL &&
 						    cuflags != JAIL_CREATE) {
 							/*
 							 * Use this jail
 							 * for updates.
 							 */
 							pr = tpr;
 							drflags |= PD_LOCKED;
 							break;
 						}
 						/*
 						 * Create, or update(jid):
 						 * name must not exist in an
 						 * active sibling jail.
 						 */
 						error = EEXIST;
 						mtx_unlock(&tpr->pr_mtx);
 						vfs_opterror(opts,
 						   "jail \"%s\" already exists",
 						   name);
 						goto done_deref;
 					}
 					if (pr == NULL &&
 					    cuflags != JAIL_CREATE &&
 					    prison_isvalid(tpr))
 						deadpr = tpr;
 					mtx_unlock(&tpr->pr_mtx);
 				}
 			}
 			/* If no active jail is found, use a dying one. */
 			if (deadpr != NULL && pr == NULL) {
 				if (flags & JAIL_DYING) {
 					mtx_lock(&deadpr->pr_mtx);
 					if (!prison_isvalid(deadpr)) {
 						mtx_unlock(&deadpr->pr_mtx);
 						goto name_again;
 					}
 					pr = deadpr;
 					drflags |= PD_LOCKED;
 				} else if (cuflags == JAIL_UPDATE) {
 					error = ENOENT;
 					vfs_opterror(opts,
 					    "jail \"%s\" is dying", name);
 					goto done_deref;
 				}
 			}
 			/* Update: name must exist if no jid. */
 			else if (cuflags == JAIL_UPDATE && pr == NULL) {
 				error = ENOENT;
 				vfs_opterror(opts, "jail \"%s\" not found",
 				    name);
 				goto done_deref;
 			}
 		}
 	}
 	/* Update: must provide a jid or name. */
 	else if (cuflags == JAIL_UPDATE && pr == NULL) {
 		error = ENOENT;
 		vfs_opterror(opts, "update specified no jail");
 		goto done_deref;
 	}
 
 	/* If there's no prison to update, create a new one and link it in. */
 	created = pr == NULL;
 	if (created) {
 		for (tpr = mypr; tpr != NULL; tpr = tpr->pr_parent)
 			if (tpr->pr_childcount >= tpr->pr_childmax) {
 				error = EPERM;
 				vfs_opterror(opts, "prison limit exceeded");
 				goto done_deref;
 			}
 		mtx_lock(&ppr->pr_mtx);
 		if (!prison_isvalid(ppr)) {
 			mtx_unlock(&ppr->pr_mtx);
 			error = ENOENT;
 			vfs_opterror(opts, "jail \"%s\" not found",
 			    prison_name(mypr, ppr));
 			goto done_deref;
 		}
 		ppr->pr_ref++;
 		ppr->pr_uref++;
 		mtx_unlock(&ppr->pr_mtx);
 
 		if (jid == 0 && (jid = get_next_prid(&inspr)) == 0) {
 			error = EAGAIN;
 			vfs_opterror(opts, "no available jail IDs");
 			pr = ppr;
 			drflags |= PD_DEREF | PD_DEUREF;
 			goto done_deref;
 		}
 
 		pr = malloc(sizeof(*pr), M_PRISON, M_WAITOK | M_ZERO);
 		LIST_INIT(&pr->pr_children);
 		mtx_init(&pr->pr_mtx, "jail mutex", NULL, MTX_DEF | MTX_DUPOK);
 		TASK_INIT(&pr->pr_task, 0, prison_complete, pr);
 
 		pr->pr_id = jid;
 		if (inspr != NULL)
 			TAILQ_INSERT_BEFORE(inspr, pr, pr_list);
 		else
 			TAILQ_INSERT_TAIL(&allprison, pr, pr_list);
 
 		pr->pr_parent = ppr;
 		LIST_INSERT_HEAD(&ppr->pr_children, pr, pr_sibling);
 		for (tpr = ppr; tpr != NULL; tpr = tpr->pr_parent)
 			tpr->pr_childcount++;
 
 		/* Set some default values, and inherit some from the parent. */
 		if (namelc == NULL)
 			namelc = "";
 		if (path == NULL) {
 			path = "/";
 			root = mypr->pr_root;
 			vref(root);
 		}
 		strlcpy(pr->pr_hostuuid, DEFAULT_HOSTUUID, HOSTUUIDLEN);
 		pr->pr_flags |= PR_HOST;
 #if defined(INET) || defined(INET6)
 #ifdef VIMAGE
 		if (!(pr_flags & PR_VNET))
 #endif
 		{
 #ifdef INET
 			if (!(ch_flags & PR_IP4_USER))
 				pr->pr_flags |= PR_IP4 | PR_IP4_USER;
 			else if (!(pr_flags & PR_IP4_USER)) {
 				pr->pr_flags |= ppr->pr_flags & PR_IP4;
 				if (ppr->pr_ip4 != NULL) {
 					pr->pr_ip4s = ppr->pr_ip4s;
 					pr->pr_ip4 = malloc(pr->pr_ip4s *
 					    sizeof(struct in_addr), M_PRISON,
 					    M_WAITOK);
 					bcopy(ppr->pr_ip4, pr->pr_ip4,
 					    pr->pr_ip4s * sizeof(*pr->pr_ip4));
 				}
 			}
 #endif
 #ifdef INET6
 			if (!(ch_flags & PR_IP6_USER))
 				pr->pr_flags |= PR_IP6 | PR_IP6_USER;
 			else if (!(pr_flags & PR_IP6_USER)) {
 				pr->pr_flags |= ppr->pr_flags & PR_IP6;
 				if (ppr->pr_ip6 != NULL) {
 					pr->pr_ip6s = ppr->pr_ip6s;
 					pr->pr_ip6 = malloc(pr->pr_ip6s *
 					    sizeof(struct in6_addr), M_PRISON,
 					    M_WAITOK);
 					bcopy(ppr->pr_ip6, pr->pr_ip6,
 					    pr->pr_ip6s * sizeof(*pr->pr_ip6));
 				}
 			}
 #endif
 		}
 #endif
 		/* Source address selection is always on by default. */
 		pr->pr_flags |= _PR_IP_SADDRSEL;
 
 		pr->pr_securelevel = ppr->pr_securelevel;
 		pr->pr_allow = JAIL_DEFAULT_ALLOW & ppr->pr_allow;
 		pr->pr_enforce_statfs = jail_default_enforce_statfs;
 		pr->pr_devfs_rsnum = ppr->pr_devfs_rsnum;
 
 		pr->pr_osreldate = osreldt ? osreldt : ppr->pr_osreldate;
 		if (osrelstr == NULL)
 			strlcpy(pr->pr_osrelease, ppr->pr_osrelease,
 			    sizeof(pr->pr_osrelease));
 		else
 			strlcpy(pr->pr_osrelease, osrelstr,
 			    sizeof(pr->pr_osrelease));
 
 #ifdef VIMAGE
 		/* Allocate a new vnet if specified. */
 		pr->pr_vnet = (pr_flags & PR_VNET)
 		    ? vnet_alloc() : ppr->pr_vnet;
 #endif
 		/*
 		 * Allocate a dedicated cpuset for each jail.
 		 * Unlike other initial settings, this may return an erorr.
 		 */
 		error = cpuset_create_root(ppr, &pr->pr_cpuset);
 		if (error)
 			goto done_deref;
 
 		mtx_lock(&pr->pr_mtx);
 		drflags |= PD_LOCKED;
 		/*
 		 * New prisons do not yet have a reference, because we do not
 		 * want others to see the incomplete prison once the
 		 * allprison_lock is downgraded.
 		 */
 	} else {
 		/*
 		 * Grab a reference for existing prisons, to ensure they
 		 * continue to exist for the duration of the call.
 		 */
 		pr->pr_ref++;
 		drflags |= PD_DEREF;
 #if defined(VIMAGE) && (defined(INET) || defined(INET6))
 		if ((pr->pr_flags & PR_VNET) &&
 		    (ch_flags & (PR_IP4_USER | PR_IP6_USER))) {
 			error = EINVAL;
 			vfs_opterror(opts,
 			    "vnet jails cannot have IP address restrictions");
 			goto done_deref;
 		}
 #endif
 #ifdef INET
 		if (PR_IP4_USER & ch_flags & (pr_flags ^ pr->pr_flags)) {
 			error = EINVAL;
 			vfs_opterror(opts,
 			    "ip4 cannot be changed after creation");
 			goto done_deref;
 		}
 #endif
 #ifdef INET6
 		if (PR_IP6_USER & ch_flags & (pr_flags ^ pr->pr_flags)) {
 			error = EINVAL;
 			vfs_opterror(opts,
 			    "ip6 cannot be changed after creation");
 			goto done_deref;
 		}
 #endif
 	}
 
 	/* Do final error checking before setting anything. */
 	if (gotslevel) {
 		if (slevel < ppr->pr_securelevel) {
 			error = EPERM;
 			goto done_deref;
 		}
 	}
 	if (gotchildmax) {
 		if (childmax >= ppr->pr_childmax) {
 			error = EPERM;
 			goto done_deref;
 		}
 	}
 	if (gotenforce) {
 		if (enforce < ppr->pr_enforce_statfs) {
 			error = EPERM;
 			goto done_deref;
 		}
 	}
 	if (gotrsnum) {
 		/*
 		 * devfs_rsnum is a uint16_t
 		 */
 		if (rsnum < 0 || rsnum > 65535) {
 			error = EINVAL;
 			goto done_deref;
 		}
 		/*
 		 * Nested jails always inherit parent's devfs ruleset
 		 */
 		if (jailed(td->td_ucred)) {
 			if (rsnum > 0 && rsnum != ppr->pr_devfs_rsnum) {
 				error = EPERM;
 				goto done_deref;
 			} else
 				rsnum = ppr->pr_devfs_rsnum;
 		}
 	}
 #ifdef INET
 	if (ip4s > 0) {
 		if (ppr->pr_flags & PR_IP4) {
 			/*
 			 * Make sure the new set of IP addresses is a
 			 * subset of the parent's list.  Don't worry
 			 * about the parent being unlocked, as any
 			 * setting is done with allprison_lock held.
 			 */
 			for (ij = 0; ij < ppr->pr_ip4s; ij++)
 				if (ip4[0].s_addr == ppr->pr_ip4[ij].s_addr)
 					break;
 			if (ij == ppr->pr_ip4s) {
 				error = EPERM;
 				goto done_deref;
 			}
 			if (ip4s > 1) {
 				for (ii = ij = 1; ii < ip4s; ii++) {
 					if (ip4[ii].s_addr ==
 					    ppr->pr_ip4[0].s_addr)
 						continue;
 					for (; ij < ppr->pr_ip4s; ij++)
 						if (ip4[ii].s_addr ==
 						    ppr->pr_ip4[ij].s_addr)
 							break;
 					if (ij == ppr->pr_ip4s)
 						break;
 				}
 				if (ij == ppr->pr_ip4s) {
 					error = EPERM;
 					goto done_deref;
 				}
 			}
 		}
 		/*
 		 * Check for conflicting IP addresses.  We permit them
 		 * if there is no more than one IP on each jail.  If
 		 * there is a duplicate on a jail with more than one
 		 * IP stop checking and return error.
 		 */
 #ifdef VIMAGE
 		for (tppr = ppr; tppr != &prison0; tppr = tppr->pr_parent)
 			if (tppr->pr_flags & PR_VNET)
 				break;
 #else
 		tppr = &prison0;
 #endif
 		FOREACH_PRISON_DESCENDANT(tppr, tpr, descend) {
 			if (tpr == pr ||
 #ifdef VIMAGE
 			    (tpr != tppr && (tpr->pr_flags & PR_VNET)) ||
 #endif
 			    tpr->pr_uref == 0) {
 				descend = 0;
 				continue;
 			}
 			if (!(tpr->pr_flags & PR_IP4_USER))
 				continue;
 			descend = 0;
 			if (tpr->pr_ip4 == NULL ||
 			    (ip4s == 1 && tpr->pr_ip4s == 1))
 				continue;
 			for (ii = 0; ii < ip4s; ii++) {
 				if (prison_check_ip4_locked(tpr, &ip4[ii]) ==
 				    0) {
 					error = EADDRINUSE;
 					vfs_opterror(opts,
 					    "IPv4 addresses clash");
 					goto done_deref;
 				}
 			}
 		}
 	}
 #endif
 #ifdef INET6
 	if (ip6s > 0) {
 		if (ppr->pr_flags & PR_IP6) {
 			/*
 			 * Make sure the new set of IP addresses is a
 			 * subset of the parent's list.
 			 */
 			for (ij = 0; ij < ppr->pr_ip6s; ij++)
 				if (IN6_ARE_ADDR_EQUAL(&ip6[0],
 				    &ppr->pr_ip6[ij]))
 					break;
 			if (ij == ppr->pr_ip6s) {
 				error = EPERM;
 				goto done_deref;
 			}
 			if (ip6s > 1) {
 				for (ii = ij = 1; ii < ip6s; ii++) {
 					if (IN6_ARE_ADDR_EQUAL(&ip6[ii],
 					     &ppr->pr_ip6[0]))
 						continue;
 					for (; ij < ppr->pr_ip6s; ij++)
 						if (IN6_ARE_ADDR_EQUAL(
 						    &ip6[ii], &ppr->pr_ip6[ij]))
 							break;
 					if (ij == ppr->pr_ip6s)
 						break;
 				}
 				if (ij == ppr->pr_ip6s) {
 					error = EPERM;
 					goto done_deref;
 				}
 			}
 		}
 		/* Check for conflicting IP addresses. */
 #ifdef VIMAGE
 		for (tppr = ppr; tppr != &prison0; tppr = tppr->pr_parent)
 			if (tppr->pr_flags & PR_VNET)
 				break;
 #else
 		tppr = &prison0;
 #endif
 		FOREACH_PRISON_DESCENDANT(tppr, tpr, descend) {
 			if (tpr == pr ||
 #ifdef VIMAGE
 			    (tpr != tppr && (tpr->pr_flags & PR_VNET)) ||
 #endif
 			    tpr->pr_uref == 0) {
 				descend = 0;
 				continue;
 			}
 			if (!(tpr->pr_flags & PR_IP6_USER))
 				continue;
 			descend = 0;
 			if (tpr->pr_ip6 == NULL ||
 			    (ip6s == 1 && tpr->pr_ip6s == 1))
 				continue;
 			for (ii = 0; ii < ip6s; ii++) {
 				if (prison_check_ip6_locked(tpr, &ip6[ii]) ==
 				    0) {
 					error = EADDRINUSE;
 					vfs_opterror(opts,
 					    "IPv6 addresses clash");
 					goto done_deref;
 				}
 			}
 		}
 	}
 #endif
 	onamelen = namelen = 0;
 	if (namelc != NULL) {
 		/* Give a default name of the jid.  Also allow the name to be
 		 * explicitly the jid - but not any other number, and only in
 		 * normal form (no leading zero/etc).
 		 */
 		if (namelc[0] == '\0')
 			snprintf(namelc = numbuf, sizeof(numbuf), "%d", jid);
 		else if ((strtoul(namelc, &p, 10) != jid ||
 			  namelc[0] < '1' || namelc[0] > '9') && *p == '\0') {
 			error = EINVAL;
 			vfs_opterror(opts,
 			    "name cannot be numeric (unless it is the jid)");
 			goto done_deref;
 		}
 		/*
 		 * Make sure the name isn't too long for the prison or its
 		 * children.
 		 */
 		pnamelen = (ppr == &prison0) ? 0 : strlen(ppr->pr_name) + 1;
 		onamelen = strlen(pr->pr_name + pnamelen);
 		namelen = strlen(namelc);
 		if (pnamelen + namelen + 1 > sizeof(pr->pr_name)) {
 			error = ENAMETOOLONG;
 			goto done_deref;
 		}
 		FOREACH_PRISON_DESCENDANT(pr, tpr, descend) {
 			if (strlen(tpr->pr_name) + (namelen - onamelen) >=
 			    sizeof(pr->pr_name)) {
 				error = ENAMETOOLONG;
 				goto done_deref;
 			}
 		}
 	}
 	pr_allow_diff = pr_allow & ~ppr->pr_allow;
 	if (pr_allow_diff & ~PR_ALLOW_DIFFERENCES) {
 		error = EPERM;
 		goto done_deref;
 	}
 
 	/*
 	 * Let modules check their parameters.  This requires unlocking and
 	 * then re-locking the prison, but this is still a valid state as long
 	 * as allprison_lock remains xlocked.
 	 */
 	mtx_unlock(&pr->pr_mtx);
 	drflags &= ~PD_LOCKED;
 	error = osd_jail_call(pr, PR_METHOD_CHECK, opts);
 	if (error != 0)
 		goto done_deref;
 	mtx_lock(&pr->pr_mtx);
 	drflags |= PD_LOCKED;
 
 	/* At this point, all valid parameters should have been noted. */
 	TAILQ_FOREACH(opt, opts, link) {
 		if (!opt->seen && strcmp(opt->name, "errmsg")) {
 			error = EINVAL;
 			vfs_opterror(opts, "unknown parameter: %s", opt->name);
 			goto done_deref;
 		}
 	}
 
 	/* Set the parameters of the prison. */
 #ifdef INET
 	redo_ip4 = 0;
 	if (pr_flags & PR_IP4_USER) {
 		pr->pr_flags |= PR_IP4;
 		free(pr->pr_ip4, M_PRISON);
 		pr->pr_ip4s = ip4s;
 		pr->pr_ip4 = ip4;
 		ip4 = NULL;
 		FOREACH_PRISON_DESCENDANT_LOCKED(pr, tpr, descend) {
 #ifdef VIMAGE
 			if (tpr->pr_flags & PR_VNET) {
 				descend = 0;
 				continue;
 			}
 #endif
 			if (prison_restrict_ip4(tpr, NULL)) {
 				redo_ip4 = 1;
 				descend = 0;
 			}
 		}
 	}
 #endif
 #ifdef INET6
 	redo_ip6 = 0;
 	if (pr_flags & PR_IP6_USER) {
 		pr->pr_flags |= PR_IP6;
 		free(pr->pr_ip6, M_PRISON);
 		pr->pr_ip6s = ip6s;
 		pr->pr_ip6 = ip6;
 		ip6 = NULL;
 		FOREACH_PRISON_DESCENDANT_LOCKED(pr, tpr, descend) {
 #ifdef VIMAGE
 			if (tpr->pr_flags & PR_VNET) {
 				descend = 0;
 				continue;
 			}
 #endif
 			if (prison_restrict_ip6(tpr, NULL)) {
 				redo_ip6 = 1;
 				descend = 0;
 			}
 		}
 	}
 #endif
 	if (gotslevel) {
 		pr->pr_securelevel = slevel;
 		/* Set all child jails to be at least this level. */
 		FOREACH_PRISON_DESCENDANT_LOCKED(pr, tpr, descend)
 			if (tpr->pr_securelevel < slevel)
 				tpr->pr_securelevel = slevel;
 	}
 	if (gotchildmax) {
 		pr->pr_childmax = childmax;
 		/* Set all child jails to under this limit. */
 		FOREACH_PRISON_DESCENDANT_LOCKED_LEVEL(pr, tpr, descend, level)
 			if (tpr->pr_childmax > childmax - level)
 				tpr->pr_childmax = childmax > level
 				    ? childmax - level : 0;
 	}
 	if (gotenforce) {
 		pr->pr_enforce_statfs = enforce;
 		/* Pass this restriction on to the children. */
 		FOREACH_PRISON_DESCENDANT_LOCKED(pr, tpr, descend)
 			if (tpr->pr_enforce_statfs < enforce)
 				tpr->pr_enforce_statfs = enforce;
 	}
 	if (gotrsnum) {
 		pr->pr_devfs_rsnum = rsnum;
 		/* Pass this restriction on to the children. */
 		FOREACH_PRISON_DESCENDANT_LOCKED(pr, tpr, descend)
 			tpr->pr_devfs_rsnum = rsnum;
 	}
 	if (namelc != NULL) {
 		if (ppr == &prison0)
 			strlcpy(pr->pr_name, namelc, sizeof(pr->pr_name));
 		else
 			snprintf(pr->pr_name, sizeof(pr->pr_name), "%s.%s",
 			    ppr->pr_name, namelc);
 		/* Change this component of child names. */
 		FOREACH_PRISON_DESCENDANT_LOCKED(pr, tpr, descend) {
 			bcopy(tpr->pr_name + onamelen, tpr->pr_name + namelen,
 			    strlen(tpr->pr_name + onamelen) + 1);
 			bcopy(pr->pr_name, tpr->pr_name, namelen);
 		}
 	}
 	if (path != NULL) {
 		/* Try to keep a real-rooted full pathname. */
 		strlcpy(pr->pr_path, path, sizeof(pr->pr_path));
 		pr->pr_root = root;
 		root = NULL;
 	}
 	if (PR_HOST & ch_flags & ~pr_flags) {
 		if (pr->pr_flags & PR_HOST) {
 			/*
 			 * Copy the parent's host info.  As with pr_ip4 above,
 			 * the lack of a lock on the parent is not a problem;
 			 * it is always set with allprison_lock at least
 			 * shared, and is held exclusively here.
 			 */
 			strlcpy(pr->pr_hostname, pr->pr_parent->pr_hostname,
 			    sizeof(pr->pr_hostname));
 			strlcpy(pr->pr_domainname, pr->pr_parent->pr_domainname,
 			    sizeof(pr->pr_domainname));
 			strlcpy(pr->pr_hostuuid, pr->pr_parent->pr_hostuuid,
 			    sizeof(pr->pr_hostuuid));
 			pr->pr_hostid = pr->pr_parent->pr_hostid;
 		}
 	} else if (host != NULL || domain != NULL || uuid != NULL || gothid) {
 		/* Set this prison, and any descendants without PR_HOST. */
 		if (host != NULL)
 			strlcpy(pr->pr_hostname, host, sizeof(pr->pr_hostname));
 		if (domain != NULL)
 			strlcpy(pr->pr_domainname, domain, 
 			    sizeof(pr->pr_domainname));
 		if (uuid != NULL)
 			strlcpy(pr->pr_hostuuid, uuid, sizeof(pr->pr_hostuuid));
 		if (gothid)
 			pr->pr_hostid = hid;
 		FOREACH_PRISON_DESCENDANT_LOCKED(pr, tpr, descend) {
 			if (tpr->pr_flags & PR_HOST)
 				descend = 0;
 			else {
 				if (host != NULL)
 					strlcpy(tpr->pr_hostname,
 					    pr->pr_hostname,
 					    sizeof(tpr->pr_hostname));
 				if (domain != NULL)
 					strlcpy(tpr->pr_domainname, 
 					    pr->pr_domainname,
 					    sizeof(tpr->pr_domainname));
 				if (uuid != NULL)
 					strlcpy(tpr->pr_hostuuid,
 					    pr->pr_hostuuid,
 					    sizeof(tpr->pr_hostuuid));
 				if (gothid)
 					tpr->pr_hostid = hid;
 			}
 		}
 	}
 	pr->pr_allow = (pr->pr_allow & ~ch_allow) | pr_allow;
 	if ((tallow = ch_allow & ~pr_allow))
 		prison_set_allow_locked(pr, tallow, 0);
 	/*
 	 * Persistent prisons get an extra reference, and prisons losing their
 	 * persist flag lose that reference.  Only do this for existing prisons
 	 * for now, so new ones will remain unseen until after the module
 	 * handlers have completed.
 	 */
 	born = !prison_isalive(pr);
 	if (!created && (ch_flags & PR_PERSIST & (pr_flags ^ pr->pr_flags))) {
 		if (pr_flags & PR_PERSIST) {
 			pr->pr_ref++;
 			pr->pr_uref++;
 		} else {
 			pr->pr_ref--;
 			pr->pr_uref--;
 		}
 	}
 	pr->pr_flags = (pr->pr_flags & ~ch_flags) | pr_flags;
 	mtx_unlock(&pr->pr_mtx);
 	drflags &= ~PD_LOCKED;
 
 #ifdef RACCT
 	if (racct_enable && created)
 		prison_racct_attach(pr);
 #endif
 
 	/* Locks may have prevented a complete restriction of child IP
 	 * addresses.  If so, allocate some more memory and try again.
 	 */
 #ifdef INET
 	while (redo_ip4) {
 		ip4s = pr->pr_ip4s;
 		ip4 = malloc(ip4s * sizeof(*ip4), M_PRISON, M_WAITOK);
 		mtx_lock(&pr->pr_mtx);
 		redo_ip4 = 0;
 		FOREACH_PRISON_DESCENDANT_LOCKED(pr, tpr, descend) {
 #ifdef VIMAGE
 			if (tpr->pr_flags & PR_VNET) {
 				descend = 0;
 				continue;
 			}
 #endif
 			if (prison_restrict_ip4(tpr, ip4)) {
 				if (ip4 != NULL)
 					ip4 = NULL;
 				else
 					redo_ip4 = 1;
 			}
 		}
 		mtx_unlock(&pr->pr_mtx);
 	}
 #endif
 #ifdef INET6
 	while (redo_ip6) {
 		ip6s = pr->pr_ip6s;
 		ip6 = malloc(ip6s * sizeof(*ip6), M_PRISON, M_WAITOK);
 		mtx_lock(&pr->pr_mtx);
 		redo_ip6 = 0;
 		FOREACH_PRISON_DESCENDANT_LOCKED(pr, tpr, descend) {
 #ifdef VIMAGE
 			if (tpr->pr_flags & PR_VNET) {
 				descend = 0;
 				continue;
 			}
 #endif
 			if (prison_restrict_ip6(tpr, ip6)) {
 				if (ip6 != NULL)
 					ip6 = NULL;
 				else
 					redo_ip6 = 1;
 			}
 		}
 		mtx_unlock(&pr->pr_mtx);
 	}
 #endif
 
 	/* Let the modules do their work. */
 	sx_downgrade(&allprison_lock);
 	drflags = (drflags & ~PD_LIST_XLOCKED) | PD_LIST_SLOCKED;
 	if (born) {
 		error = osd_jail_call(pr, PR_METHOD_CREATE, opts);
 		if (error) {
 			(void)osd_jail_call(pr, PR_METHOD_REMOVE, NULL);
 			goto done_deref;
 		}
 	}
 	error = osd_jail_call(pr, PR_METHOD_SET, opts);
 	if (error) {
 		if (born)
 			(void)osd_jail_call(pr, PR_METHOD_REMOVE, NULL);
 		goto done_deref;
 	}
 
 	/* Attach this process to the prison if requested. */
 	if (flags & JAIL_ATTACH) {
 		mtx_lock(&pr->pr_mtx);
 		error = do_jail_attach(td, pr);
 		drflags &= ~PD_LIST_SLOCKED;
 		if (error) {
 			if (created) {
 				/* do_jail_attach has removed the prison. */
 				pr = NULL;
 			}
 			vfs_opterror(opts, "attach failed");
 			goto done_deref;
 		}
 	}
 
 #ifdef RACCT
 	if (racct_enable && !created) {
 		if (drflags & PD_LIST_SLOCKED) {
 			sx_sunlock(&allprison_lock);
 			drflags &= ~PD_LIST_SLOCKED;
 		}
 		prison_racct_modify(pr);
 	}
 #endif
 
 	td->td_retval[0] = pr->pr_id;
 
 	if (created) {
 		/*
 		 * Add a reference to newly created persistent prisons
 		 * (which was not done earlier so that the prison would
 		 * not be publicly visible).
 		 */
 		if (pr_flags & PR_PERSIST) {
 			mtx_lock(&pr->pr_mtx);
 			drflags |= PD_LOCKED;
 			pr->pr_ref++;
 			pr->pr_uref++;
 		} else {
 			/* Non-persistent jails need no further changes. */
 			pr = NULL;
 		}
 	}
 
  done_deref:
 	/* Release any temporary prison holds and/or locks. */
 	if (pr != NULL)
 		prison_deref(pr, drflags);
 	else if (drflags & PD_LIST_SLOCKED)
 		sx_sunlock(&allprison_lock);
 	else if (drflags & PD_LIST_XLOCKED)
 		sx_xunlock(&allprison_lock);
 	if (root != NULL)
 		vrele(root);
  done_errmsg:
 	if (error) {
 		/* Write the error message back to userspace. */
 		if (vfs_getopt(opts, "errmsg", (void **)&errmsg,
 		    &errmsg_len) == 0 && errmsg_len > 0) {
 			errmsg_pos = 2 * vfs_getopt_pos(opts, "errmsg") + 1;
 			if (optuio->uio_segflg == UIO_SYSSPACE)
 				bcopy(errmsg,
 				    optuio->uio_iov[errmsg_pos].iov_base,
 				    errmsg_len);
 			else
 				copyout(errmsg,
 				    optuio->uio_iov[errmsg_pos].iov_base,
 				    errmsg_len);
 		}
 	}
  done_free:
 #ifdef INET
 	free(ip4, M_PRISON);
 #endif
 #ifdef INET6
 	free(ip6, M_PRISON);
 #endif
 	if (g_path != NULL)
 		free(g_path, M_TEMP);
 	vfs_freeopts(opts);
 	return (error);
 }
 
 /*
  * Find the next available prison ID.  Return the ID on success, or zero
  * on failure.  Also set a pointer to the allprison list entry the prison
  * should be inserted before.
  */
 static int
 get_next_prid(struct prison **insprp)
 {
 	struct prison *inspr;
 	int jid, maxid;
 
 	jid = lastprid % JAIL_MAX + 1;
 	if (TAILQ_EMPTY(&allprison) ||
 	    TAILQ_LAST(&allprison, prisonlist)->pr_id < jid) {
 		/*
 		 * A common case is for all jails to be implicitly numbered,
 		 * which means they'll go on the end of the list, at least
 		 * for the first JAIL_MAX times.
 		 */
 		inspr = NULL;
 	} else {
 		/*
 		 * Take two passes through the allprison list: first starting
 		 * with the proposed jid, then ending with it.
 		 */
 		for (maxid = JAIL_MAX; maxid != 0; ) {
 			TAILQ_FOREACH(inspr, &allprison, pr_list) {
 				if (inspr->pr_id < jid)
 					continue;
 				if (inspr->pr_id > jid || inspr->pr_ref == 0) {
 					/*
 					 * Found an opening.  This may be a gap
 					 * in the list, or a dead jail with the
 					 * same ID.
 					 */
 					maxid = 0;
 					break;
 				}
 				if (++jid > maxid) {
 					if (lastprid == maxid || lastprid == 0)
 					{
 						/*
 						 * The entire legal range
 						 * has been traversed
 						 */
 						return 0;
 					}
 					/* Try again from the start. */
 					jid = 1;
 					maxid = lastprid;
 					break;
 				}
 			}
 			if (inspr == NULL) {
 				/* Found room at the end of the list. */
 				break;
 			}
 		}
 	}
 	*insprp = inspr;
 	lastprid = jid;
 	return (jid);
 }
 
 /*
  * struct jail_get_args {
  *	struct iovec *iovp;
  *	unsigned int iovcnt;
  *	int flags;
  * };
  */
 int
 sys_jail_get(struct thread *td, struct jail_get_args *uap)
 {
 	struct uio *auio;
 	int error;
 
 	/* Check that we have an even number of iovecs. */
 	if (uap->iovcnt & 1)
 		return (EINVAL);
 
 	error = copyinuio(uap->iovp, uap->iovcnt, &auio);
 	if (error)
 		return (error);
 	error = kern_jail_get(td, auio, uap->flags);
 	if (error == 0)
 		error = copyout(auio->uio_iov, uap->iovp,
 		    uap->iovcnt * sizeof (struct iovec));
 	free(auio, M_IOV);
 	return (error);
 }
 
 int
 kern_jail_get(struct thread *td, struct uio *optuio, int flags)
 {
 	struct bool_flags *bf;
 	struct jailsys_flags *jsf;
 	struct prison *pr, *mypr;
 	struct vfsopt *opt;
 	struct vfsoptlist *opts;
 	char *errmsg, *name;
 	int drflags, error, errmsg_len, errmsg_pos, i, jid, len, pos;
 	unsigned f;
 
 	if (flags & ~JAIL_GET_MASK)
 		return (EINVAL);
 
 	/* Get the parameter list. */
 	error = vfs_buildopts(optuio, &opts);
 	if (error)
 		return (error);
 	errmsg_pos = vfs_getopt_pos(opts, "errmsg");
 	mypr = td->td_ucred->cr_prison;
 	pr = NULL;
 
 	/*
 	 * Find the prison specified by one of: lastjid, jid, name.
 	 */
 	sx_slock(&allprison_lock);
 	drflags = PD_LIST_SLOCKED;
 	error = vfs_copyopt(opts, "lastjid", &jid, sizeof(jid));
 	if (error == 0) {
 		TAILQ_FOREACH(pr, &allprison, pr_list) {
 			if (pr->pr_id > jid && prison_ischild(mypr, pr)) {
 				mtx_lock(&pr->pr_mtx);
 				if ((flags & JAIL_DYING)
 				    ? prison_isvalid(pr) : prison_isalive(pr))
 					break;
 				mtx_unlock(&pr->pr_mtx);
 			}
 		}
 		if (pr != NULL) {
 			drflags |= PD_LOCKED;
 			goto found_prison;
 		}
 		error = ENOENT;
 		vfs_opterror(opts, "no jail after %d", jid);
 		goto done;
 	} else if (error != ENOENT)
 		goto done;
 
 	error = vfs_copyopt(opts, "jid", &jid, sizeof(jid));
 	if (error == 0) {
 		if (jid != 0) {
 			pr = prison_find_child(mypr, jid);
 			if (pr != NULL) {
 				drflags |= PD_LOCKED;
 				if (!(prison_isalive(pr) ||
 				    (flags & JAIL_DYING))) {
 					error = ENOENT;
 					vfs_opterror(opts, "jail %d is dying",
 					    jid);
 					goto done;
 				}
 				goto found_prison;
 			}
 			error = ENOENT;
 			vfs_opterror(opts, "jail %d not found", jid);
 			goto done;
 		}
 	} else if (error != ENOENT)
 		goto done;
 
 	error = vfs_getopt(opts, "name", (void **)&name, &len);
 	if (error == 0) {
 		if (len == 0 || name[len - 1] != '\0') {
 			error = EINVAL;
 			goto done;
 		}
 		pr = prison_find_name(mypr, name);
 		if (pr != NULL) {
 			drflags |= PD_LOCKED;
 			if (!(prison_isalive(pr) || (flags & JAIL_DYING))) {
 				error = ENOENT;
 				vfs_opterror(opts, "jail \"%s\" is dying",
 				    name);
 				goto done;
 			}
 			goto found_prison;
 		}
 		error = ENOENT;
 		vfs_opterror(opts, "jail \"%s\" not found", name);
 		goto done;
 	} else if (error != ENOENT)
 		goto done;
 
 	vfs_opterror(opts, "no jail specified");
 	error = ENOENT;
 	goto done;
 
  found_prison:
 	/* Get the parameters of the prison. */
 	pr->pr_ref++;
 	drflags |= PD_DEREF;
 	td->td_retval[0] = pr->pr_id;
 	error = vfs_setopt(opts, "jid", &pr->pr_id, sizeof(pr->pr_id));
 	if (error != 0 && error != ENOENT)
 		goto done;
 	i = (pr->pr_parent == mypr) ? 0 : pr->pr_parent->pr_id;
 	error = vfs_setopt(opts, "parent", &i, sizeof(i));
 	if (error != 0 && error != ENOENT)
 		goto done;
 	error = vfs_setopts(opts, "name", prison_name(mypr, pr));
 	if (error != 0 && error != ENOENT)
 		goto done;
 	error = vfs_setopt(opts, "cpuset.id", &pr->pr_cpuset->cs_id,
 	    sizeof(pr->pr_cpuset->cs_id));
 	if (error != 0 && error != ENOENT)
 		goto done;
 	error = vfs_setopts(opts, "path", prison_path(mypr, pr));
 	if (error != 0 && error != ENOENT)
 		goto done;
 #ifdef INET
 	error = vfs_setopt_part(opts, "ip4.addr", pr->pr_ip4,
 	    pr->pr_ip4s * sizeof(*pr->pr_ip4));
 	if (error != 0 && error != ENOENT)
 		goto done;
 #endif
 #ifdef INET6
 	error = vfs_setopt_part(opts, "ip6.addr", pr->pr_ip6,
 	    pr->pr_ip6s * sizeof(*pr->pr_ip6));
 	if (error != 0 && error != ENOENT)
 		goto done;
 #endif
 	error = vfs_setopt(opts, "securelevel", &pr->pr_securelevel,
 	    sizeof(pr->pr_securelevel));
 	if (error != 0 && error != ENOENT)
 		goto done;
 	error = vfs_setopt(opts, "children.cur", &pr->pr_childcount,
 	    sizeof(pr->pr_childcount));
 	if (error != 0 && error != ENOENT)
 		goto done;
 	error = vfs_setopt(opts, "children.max", &pr->pr_childmax,
 	    sizeof(pr->pr_childmax));
 	if (error != 0 && error != ENOENT)
 		goto done;
 	error = vfs_setopts(opts, "host.hostname", pr->pr_hostname);
 	if (error != 0 && error != ENOENT)
 		goto done;
 	error = vfs_setopts(opts, "host.domainname", pr->pr_domainname);
 	if (error != 0 && error != ENOENT)
 		goto done;
 	error = vfs_setopts(opts, "host.hostuuid", pr->pr_hostuuid);
 	if (error != 0 && error != ENOENT)
 		goto done;
 #ifdef COMPAT_FREEBSD32
 	if (SV_PROC_FLAG(td->td_proc, SV_ILP32)) {
 		uint32_t hid32 = pr->pr_hostid;
 
 		error = vfs_setopt(opts, "host.hostid", &hid32, sizeof(hid32));
 	} else
 #endif
 	error = vfs_setopt(opts, "host.hostid", &pr->pr_hostid,
 	    sizeof(pr->pr_hostid));
 	if (error != 0 && error != ENOENT)
 		goto done;
 	error = vfs_setopt(opts, "enforce_statfs", &pr->pr_enforce_statfs,
 	    sizeof(pr->pr_enforce_statfs));
 	if (error != 0 && error != ENOENT)
 		goto done;
 	error = vfs_setopt(opts, "devfs_ruleset", &pr->pr_devfs_rsnum,
 	    sizeof(pr->pr_devfs_rsnum));
 	if (error != 0 && error != ENOENT)
 		goto done;
 	for (bf = pr_flag_bool;
 	     bf < pr_flag_bool + nitems(pr_flag_bool);
 	     bf++) {
 		i = (pr->pr_flags & bf->flag) ? 1 : 0;
 		error = vfs_setopt(opts, bf->name, &i, sizeof(i));
 		if (error != 0 && error != ENOENT)
 			goto done;
 		i = !i;
 		error = vfs_setopt(opts, bf->noname, &i, sizeof(i));
 		if (error != 0 && error != ENOENT)
 			goto done;
 	}
 	for (jsf = pr_flag_jailsys;
 	     jsf < pr_flag_jailsys + nitems(pr_flag_jailsys);
 	     jsf++) {
 		f = pr->pr_flags & (jsf->disable | jsf->new);
 		i = (f != 0 && f == jsf->disable) ? JAIL_SYS_DISABLE
 		    : (f == jsf->new) ? JAIL_SYS_NEW
 		    : JAIL_SYS_INHERIT;
 		error = vfs_setopt(opts, jsf->name, &i, sizeof(i));
 		if (error != 0 && error != ENOENT)
 			goto done;
 	}
 	for (bf = pr_flag_allow;
 	     bf < pr_flag_allow + nitems(pr_flag_allow) &&
 		atomic_load_int(&bf->flag) != 0;
 	     bf++) {
 		i = (pr->pr_allow & bf->flag) ? 1 : 0;
 		error = vfs_setopt(opts, bf->name, &i, sizeof(i));
 		if (error != 0 && error != ENOENT)
 			goto done;
 		i = !i;
 		error = vfs_setopt(opts, bf->noname, &i, sizeof(i));
 		if (error != 0 && error != ENOENT)
 			goto done;
 	}
 	i = !prison_isalive(pr);
 	error = vfs_setopt(opts, "dying", &i, sizeof(i));
 	if (error != 0 && error != ENOENT)
 		goto done;
 	i = !i;
 	error = vfs_setopt(opts, "nodying", &i, sizeof(i));
 	if (error != 0 && error != ENOENT)
 		goto done;
 	error = vfs_setopt(opts, "osreldate", &pr->pr_osreldate,
 	    sizeof(pr->pr_osreldate));
 	if (error != 0 && error != ENOENT)
 		goto done;
 	error = vfs_setopts(opts, "osrelease", pr->pr_osrelease);
 	if (error != 0 && error != ENOENT)
 		goto done;
 
 	/* Get the module parameters. */
 	mtx_unlock(&pr->pr_mtx);
 	drflags &= ~PD_LOCKED;
 	error = osd_jail_call(pr, PR_METHOD_GET, opts);
 	if (error)
 		goto done;
 	prison_deref(pr, drflags);
 	pr = NULL;
 	drflags = 0;
 
 	/* By now, all parameters should have been noted. */
 	TAILQ_FOREACH(opt, opts, link) {
 		if (!opt->seen && strcmp(opt->name, "errmsg")) {
 			error = EINVAL;
 			vfs_opterror(opts, "unknown parameter: %s", opt->name);
 			goto done;
 		}
 	}
 
 	/* Write the fetched parameters back to userspace. */
 	error = 0;
 	TAILQ_FOREACH(opt, opts, link) {
 		if (opt->pos >= 0 && opt->pos != errmsg_pos) {
 			pos = 2 * opt->pos + 1;
 			optuio->uio_iov[pos].iov_len = opt->len;
 			if (opt->value != NULL) {
 				if (optuio->uio_segflg == UIO_SYSSPACE) {
 					bcopy(opt->value,
 					    optuio->uio_iov[pos].iov_base,
 					    opt->len);
 				} else {
 					error = copyout(opt->value,
 					    optuio->uio_iov[pos].iov_base,
 					    opt->len);
 					if (error)
 						break;
 				}
 			}
 		}
 	}
 
  done:
 	/* Release any temporary prison holds and/or locks. */
 	if (pr != NULL)
 		prison_deref(pr, drflags);
 	else if (drflags & PD_LIST_SLOCKED)
 		sx_sunlock(&allprison_lock);
 	if (error && errmsg_pos >= 0) {
 		/* Write the error message back to userspace. */
 		vfs_getopt(opts, "errmsg", (void **)&errmsg, &errmsg_len);
 		errmsg_pos = 2 * errmsg_pos + 1;
 		if (errmsg_len > 0) {
 			if (optuio->uio_segflg == UIO_SYSSPACE)
 				bcopy(errmsg,
 				    optuio->uio_iov[errmsg_pos].iov_base,
 				    errmsg_len);
 			else
 				copyout(errmsg,
 				    optuio->uio_iov[errmsg_pos].iov_base,
 				    errmsg_len);
 		}
 	}
 	vfs_freeopts(opts);
 	return (error);
 }
 
 /*
  * struct jail_remove_args {
  *	int jid;
  * };
  */
 int
 sys_jail_remove(struct thread *td, struct jail_remove_args *uap)
 {
 	struct prison *pr, *cpr, *lpr, *tpr;
 	int descend, error;
 
 	error = priv_check(td, PRIV_JAIL_REMOVE);
 	if (error)
 		return (error);
 
 	sx_xlock(&allprison_lock);
 	pr = prison_find_child(td->td_ucred->cr_prison, uap->jid);
 	if (pr == NULL) {
 		sx_xunlock(&allprison_lock);
 		return (EINVAL);
 	}
 
 	/* Remove all descendants of this prison, then remove this prison. */
 	pr->pr_ref++;
 	if (!LIST_EMPTY(&pr->pr_children)) {
 		mtx_unlock(&pr->pr_mtx);
 		lpr = NULL;
 		FOREACH_PRISON_DESCENDANT(pr, cpr, descend) {
 			mtx_lock(&cpr->pr_mtx);
 			if (prison_isvalid(cpr)) {
 				tpr = cpr;
 				cpr->pr_ref++;
 			} else {
 				/* Already removed - do not do it again. */
 				tpr = NULL;
 			}
 			mtx_unlock(&cpr->pr_mtx);
 			if (lpr != NULL) {
 				mtx_lock(&lpr->pr_mtx);
 				prison_remove_one(lpr);
 				sx_xlock(&allprison_lock);
 			}
 			lpr = tpr;
 		}
 		if (lpr != NULL) {
 			mtx_lock(&lpr->pr_mtx);
 			prison_remove_one(lpr);
 			sx_xlock(&allprison_lock);
 		}
 		mtx_lock(&pr->pr_mtx);
 	}
 	prison_remove_one(pr);
 	return (0);
 }
 
 static void
 prison_remove_one(struct prison *pr)
 {
 	struct proc *p;
 	int drflags;
 
 	drflags = PD_DEREF | PD_LOCKED | PD_LIST_XLOCKED;
 
 	/* If the prison was persistent, it is not anymore. */
 	if (pr->pr_flags & PR_PERSIST) {
 		pr->pr_ref--;
 		drflags |= PD_DEUREF;
 		pr->pr_flags &= ~PR_PERSIST;
 	}
 
 	/*
 	 * jail_remove added a reference.  If that's the only one, remove
 	 * the prison now.
 	 */
 	KASSERT(pr->pr_ref > 0,
 	    ("prison_remove_one removing a dead prison (jid=%d)", pr->pr_id));
 	if (pr->pr_ref == 1) {
 		prison_deref(pr, drflags);
 		return;
 	}
 
 	mtx_unlock(&pr->pr_mtx);
 	sx_xunlock(&allprison_lock);
 	drflags &= ~(PD_LOCKED | PD_LIST_XLOCKED);
 	/*
 	 * Kill all processes unfortunate enough to be attached to this prison.
 	 */
 	sx_slock(&allproc_lock);
 	FOREACH_PROC_IN_SYSTEM(p) {
 		PROC_LOCK(p);
 		if (p->p_state != PRS_NEW && p->p_ucred &&
 		    p->p_ucred->cr_prison == pr)
 			kern_psignal(p, SIGKILL);
 		PROC_UNLOCK(p);
 	}
 	sx_sunlock(&allproc_lock);
 	/* Remove the temporary reference added by jail_remove. */
 	prison_deref(pr, drflags);
 }
 
 /*
  * struct jail_attach_args {
  *	int jid;
  * };
  */
 int
 sys_jail_attach(struct thread *td, struct jail_attach_args *uap)
 {
 	struct prison *pr;
 	int error;
 
 	error = priv_check(td, PRIV_JAIL_ATTACH);
 	if (error)
 		return (error);
 
 	/*
 	 * Start with exclusive hold on allprison_lock to ensure that a possible
 	 * PR_METHOD_REMOVE call isn't concurrent with jail_set or jail_remove.
 	 * But then immediately downgrade it since we don't need to stop
 	 * readers.
 	 */
 	sx_xlock(&allprison_lock);
 	sx_downgrade(&allprison_lock);
 	pr = prison_find_child(td->td_ucred->cr_prison, uap->jid);
 	if (pr == NULL) {
 		sx_sunlock(&allprison_lock);
 		return (EINVAL);
 	}
 
 	/* Do not allow a process to attach to a prison that is not alive. */
 	if (!prison_isalive(pr)) {
 		mtx_unlock(&pr->pr_mtx);
 		sx_sunlock(&allprison_lock);
 		return (EINVAL);
 	}
 
 	return (do_jail_attach(td, pr));
 }
 
 static int
 do_jail_attach(struct thread *td, struct prison *pr)
 {
 	struct proc *p;
 	struct ucred *newcred, *oldcred;
 	int error;
 
 	/*
 	 * XXX: Note that there is a slight race here if two threads
 	 * in the same privileged process attempt to attach to two
 	 * different jails at the same time.  It is important for
 	 * user processes not to do this, or they might end up with
 	 * a process root from one prison, but attached to the jail
 	 * of another.
 	 */
 	pr->pr_ref++;
 	pr->pr_uref++;
 	mtx_unlock(&pr->pr_mtx);
 
 	/* Let modules do whatever they need to prepare for attaching. */
 	error = osd_jail_call(pr, PR_METHOD_ATTACH, td);
 	if (error) {
 		prison_deref(pr, PD_DEREF | PD_DEUREF | PD_LIST_SLOCKED);
 		return (error);
 	}
 	sx_sunlock(&allprison_lock);
 
 	/*
 	 * Reparent the newly attached process to this jail.
 	 */
 	p = td->td_proc;
 	error = cpuset_setproc_update_set(p, pr->pr_cpuset);
 	if (error)
 		goto e_revert_osd;
 
 	vn_lock(pr->pr_root, LK_EXCLUSIVE | LK_RETRY);
 	if ((error = change_dir(pr->pr_root, td)) != 0)
 		goto e_unlock;
 #ifdef MAC
 	if ((error = mac_vnode_check_chroot(td->td_ucred, pr->pr_root)))
 		goto e_unlock;
 #endif
 	VOP_UNLOCK(pr->pr_root);
 	if ((error = pwd_chroot(td, pr->pr_root)))
 		goto e_revert_osd;
 
 	newcred = crget();
 	PROC_LOCK(p);
 	oldcred = crcopysafe(p, newcred);
 	newcred->cr_prison = pr;
 	proc_set_cred(p, newcred);
 	setsugid(p);
 #ifdef RACCT
 	racct_proc_ucred_changed(p, oldcred, newcred);
 	crhold(newcred);
 #endif
 	PROC_UNLOCK(p);
 #ifdef RCTL
 	rctl_proc_ucred_changed(p, newcred);
 	crfree(newcred);
 #endif
 	prison_deref(oldcred->cr_prison, PD_DEREF | PD_DEUREF);
 	crfree(oldcred);
 	return (0);
 
  e_unlock:
 	VOP_UNLOCK(pr->pr_root);
  e_revert_osd:
 	/* Tell modules this thread is still in its old jail after all. */
 	sx_slock(&allprison_lock);
 	(void)osd_jail_call(td->td_ucred->cr_prison, PR_METHOD_ATTACH, td);
 	prison_deref(pr, PD_DEREF | PD_DEUREF | PD_LIST_SLOCKED);
 	return (error);
 }
 
 /*
  * Returns a locked prison instance, or NULL on failure.
  */
 struct prison *
 prison_find(int prid)
 {
 	struct prison *pr;
 
 	sx_assert(&allprison_lock, SX_LOCKED);
 	TAILQ_FOREACH(pr, &allprison, pr_list) {
 		if (pr->pr_id == prid) {
 			mtx_lock(&pr->pr_mtx);
 			if (prison_isvalid(pr))
 				return (pr);
 			/*
 			 * Any active prison with the same ID would have
 			 * been inserted before a dead one.
 			 */
 			mtx_unlock(&pr->pr_mtx);
 			break;
 		}
 		if (pr->pr_id > prid)
 			break;
 	}
 	return (NULL);
 }
 
 /*
  * Find a prison that is a descendant of mypr.  Returns a locked prison or NULL.
  */
 struct prison *
 prison_find_child(struct prison *mypr, int prid)
 {
 	struct prison *pr;
 	int descend;
 
 	sx_assert(&allprison_lock, SX_LOCKED);
 	FOREACH_PRISON_DESCENDANT(mypr, pr, descend) {
 		if (pr->pr_id == prid) {
 			mtx_lock(&pr->pr_mtx);
 			if (prison_isvalid(pr))
 				return (pr);
 			mtx_unlock(&pr->pr_mtx);
 		}
 	}
 	return (NULL);
 }
 
 /*
  * Look for the name relative to mypr.  Returns a locked prison or NULL.
  */
 struct prison *
 prison_find_name(struct prison *mypr, const char *name)
 {
 	struct prison *pr, *deadpr;
 	size_t mylen;
 	int descend;
 
 	sx_assert(&allprison_lock, SX_LOCKED);
 	mylen = (mypr == &prison0) ? 0 : strlen(mypr->pr_name) + 1;
  again:
 	deadpr = NULL;
 	FOREACH_PRISON_DESCENDANT(mypr, pr, descend) {
 		if (!strcmp(pr->pr_name + mylen, name)) {
 			mtx_lock(&pr->pr_mtx);
 			if (prison_isalive(pr))
 				return (pr);
 			if (prison_isvalid(pr))
 				deadpr = pr;
 			mtx_unlock(&pr->pr_mtx);
 		}
 	}
 	/* There was no valid prison - perhaps there was a dying one. */
 	if (deadpr != NULL) {
 		mtx_lock(&deadpr->pr_mtx);
 		if (!prison_isvalid(deadpr)) {
 			mtx_unlock(&deadpr->pr_mtx);
 			goto again;
 		}
 	}
 	return (deadpr);
 }
 
 /*
  * See if a prison has the specific flag set.  The prison should be locked,
  * unless checking for flags that are only set at jail creation (such as
  * PR_IP4 and PR_IP6), or only the single bit is examined, without regard
  * to any other prison data.
  */
 int
 prison_flag(struct ucred *cred, unsigned flag)
 {
 
 	return (cred->cr_prison->pr_flags & flag);
 }
 
 int
 prison_allow(struct ucred *cred, unsigned flag)
 {
 
 	return ((cred->cr_prison->pr_allow & flag) != 0);
 }
 
 /*
- * Remove a prison reference.  If that was the last reference, remove the
- * prison itself - but not in this context in case there are locks held.
+ * Hold a prison reference, by incrementing pr_ref.  It is generally
+ * an error to hold a prison that does not already have a reference.
+ * A prison record will remain valid as long as it has at least one
+ * reference, and will not be removed as long as either the prison
+ * mutex or the allprison lock is held (allprison_lock may be shared).
+ */
+void
+prison_hold_locked(struct prison *pr)
+{
+
+	mtx_assert(&pr->pr_mtx, MA_OWNED);
+	KASSERT(pr->pr_ref > 0,
+	    ("Trying to hold dead prison %p (jid=%d).", pr, pr->pr_id));
+	pr->pr_ref++;
+}
+
+void
+prison_hold(struct prison *pr)
+{
+
+	mtx_lock(&pr->pr_mtx);
+	prison_hold_locked(pr);
+	mtx_unlock(&pr->pr_mtx);
+}
+
+/*
+ * Remove a prison reference.  If that was the last reference, the
+ * prison will be removed (at a later time).  Return with the prison
+ * unlocked.
  */
 void
 prison_free_locked(struct prison *pr)
 {
 	int ref;
 
 	mtx_assert(&pr->pr_mtx, MA_OWNED);
 	ref = --pr->pr_ref;
 	mtx_unlock(&pr->pr_mtx);
-	if (ref == 0)
+	if (ref == 0) {
+		/*
+		 * Don't remove the last reference in this context,
+		 * in case there are locks held.
+		 */
 		taskqueue_enqueue(taskqueue_thread, &pr->pr_task);
+	}
 }
 
 void
 prison_free(struct prison *pr)
 {
 
 	mtx_lock(&pr->pr_mtx);
 	prison_free_locked(pr);
 }
 
+/*
+ * Hold a a prison for user visibility, by incrementing pr_uref.
+ * It is generally an error to hold a prison that isn't already
+ * user-visible, except through the the jail system calls.  It is also
+ * an error to hold an invalid prison.  A prison record will remain
+ * alive as long as it has at least one user reference, and will not
+ * be set to the dying state was long as the prison mutex is held.
+ */
+void
+prison_proc_hold(struct prison *pr)
+{
+
+	mtx_lock(&pr->pr_mtx);
+	KASSERT(pr->pr_uref > 0,
+	    ("Cannot add a process to a non-alive prison (jid=%d)", pr->pr_id));
+	pr->pr_uref++;
+	mtx_unlock(&pr->pr_mtx);
+}
+
+/*
+ * Remove a prison user reference.  If it was the last reference, the
+ * prison will be considered "dying", and may be removed once all of
+ * its references are dropped.
+ */
+void
+prison_proc_free(struct prison *pr)
+{
+
+	mtx_lock(&pr->pr_mtx);
+	KASSERT(pr->pr_uref > 0,
+	    ("Trying to kill a process in a dead prison (jid=%d)", pr->pr_id));
+	if (pr->pr_uref > 1)
+		pr->pr_uref--;
+	else {
+		/*
+		 * Don't remove the last user reference in this context,
+		 * which is expected to be a process that is not only locked,
+		 * but also half dead.  Add a reference so any calls to
+		 * prison_free() won't re-submit the task.
+		 */
+		pr->pr_ref++;
+		mtx_unlock(&pr->pr_mtx);
+		taskqueue_enqueue(taskqueue_thread, &pr->pr_task);
+		return;
+	}
+	mtx_unlock(&pr->pr_mtx);
+}
+
 /*
  * Complete a call to either prison_free or prison_proc_free.
  */
 static void
 prison_complete(void *context, int pending)
 {
 	struct prison *pr = context;
 
 	sx_xlock(&allprison_lock);
 	mtx_lock(&pr->pr_mtx);
-	prison_deref(pr, pr->pr_uref
+	/*
+	 * If this is completing a call to prison_proc_free, there will still
+	 * be a user reference held; clear that as well as the reference that
+	 * was added.  No references are expected if this is completing a call
+	 * to prison_free, but prison_deref is still called for the cleanup.
+	 */
+	prison_deref(pr, pr->pr_uref > 0
 	    ? PD_DEREF | PD_DEUREF | PD_LOCKED | PD_LIST_XLOCKED
 	    : PD_LOCKED | PD_LIST_XLOCKED);
 }
 
 /*
- * Remove a prison reference (usually).  This internal version assumes no
- * mutexes are held, except perhaps the prison itself.  If there are no more
- * references, release and delist the prison.  On completion, the prison lock
- * and the allprison lock are both unlocked.
+ * Remove a prison reference and/or user reference (usually).
+ * This assumes context that allows sleeping (for allprison_lock),
+ * with no non-sleeping locks held, except perhaps the prison itself.
+ * If there are no more references, release and delist the prison.
+ * On completion, the prison lock and the allprison lock are both
+ * unlocked.
  */
 static void
 prison_deref(struct prison *pr, int flags)
 {
 	struct prison *ppr, *tpr;
 	int ref, lasturef;
 
 	if (!(flags & PD_LOCKED))
 		mtx_lock(&pr->pr_mtx);
 	for (;;) {
 		if (flags & PD_DEUREF) {
 			KASSERT(pr->pr_uref > 0,
 			    ("prison_deref PD_DEUREF on a dead prison (jid=%d)",
 			     pr->pr_id));
 			pr->pr_uref--;
 			lasturef = pr->pr_uref == 0;
 			if (lasturef)
 				pr->pr_ref++;
 			KASSERT(prison0.pr_uref != 0, ("prison0 pr_uref=0"));
 		} else
 			lasturef = 0;
 		if (flags & PD_DEREF) {
 			KASSERT(pr->pr_ref > 0,
 			    ("prison_deref PD_DEREF on a dead prison (jid=%d)",
 			     pr->pr_id));
 			pr->pr_ref--;
 		}
 		ref = pr->pr_ref;
 		mtx_unlock(&pr->pr_mtx);
 
 		/*
 		 * Tell the modules if the last user reference was removed
 		 * (even it sticks around in dying state).
 		 */
 		if (lasturef) {
 			if (!(flags & (PD_LIST_SLOCKED | PD_LIST_XLOCKED))) {
 				if (ref > 1) {
 					sx_slock(&allprison_lock);
 					flags |= PD_LIST_SLOCKED;
 				} else {
 					sx_xlock(&allprison_lock);
 					flags |= PD_LIST_XLOCKED;
 				}
 			}
 			(void)osd_jail_call(pr, PR_METHOD_REMOVE, NULL);
 			mtx_lock(&pr->pr_mtx);
 			ref = --pr->pr_ref;
 			mtx_unlock(&pr->pr_mtx);
 		}
 
 		/* If the prison still has references, nothing else to do. */
 		if (ref > 0) {
 			if (flags & PD_LIST_SLOCKED)
 				sx_sunlock(&allprison_lock);
 			else if (flags & PD_LIST_XLOCKED)
 				sx_xunlock(&allprison_lock);
 			return;
 		}
 
 		if (flags & PD_LIST_SLOCKED) {
 			if (!sx_try_upgrade(&allprison_lock)) {
 				sx_sunlock(&allprison_lock);
 				sx_xlock(&allprison_lock);
 			}
 		} else if (!(flags & PD_LIST_XLOCKED))
 			sx_xlock(&allprison_lock);
 
 		TAILQ_REMOVE(&allprison, pr, pr_list);
 		LIST_REMOVE(pr, pr_sibling);
 		ppr = pr->pr_parent;
 		for (tpr = ppr; tpr != NULL; tpr = tpr->pr_parent)
 			tpr->pr_childcount--;
 		sx_xunlock(&allprison_lock);
 
 #ifdef VIMAGE
 		if (pr->pr_vnet != ppr->pr_vnet)
 			vnet_destroy(pr->pr_vnet);
 #endif
 		if (pr->pr_root != NULL)
 			vrele(pr->pr_root);
 		mtx_destroy(&pr->pr_mtx);
 #ifdef INET
 		free(pr->pr_ip4, M_PRISON);
 #endif
 #ifdef INET6
 		free(pr->pr_ip6, M_PRISON);
 #endif
 		if (pr->pr_cpuset != NULL)
 			cpuset_rel(pr->pr_cpuset);
 		osd_jail_exit(pr);
 #ifdef RACCT
 		if (racct_enable)
 			prison_racct_detach(pr);
 #endif
 		free(pr, M_PRISON);
 
 		/* Removing a prison frees a reference on its parent. */
 		pr = ppr;
 		mtx_lock(&pr->pr_mtx);
 		flags = PD_DEREF | PD_DEUREF;
 	}
 }
 
-void
-prison_hold_locked(struct prison *pr)
-{
-
-	mtx_assert(&pr->pr_mtx, MA_OWNED);
-	KASSERT(pr->pr_ref > 0,
-	    ("Trying to hold dead prison %p (jid=%d).", pr, pr->pr_id));
-	pr->pr_ref++;
-}
-
-void
-prison_hold(struct prison *pr)
-{
-
-	mtx_lock(&pr->pr_mtx);
-	prison_hold_locked(pr);
-	mtx_unlock(&pr->pr_mtx);
-}
-
-void
-prison_proc_hold(struct prison *pr)
-{
-
-	mtx_lock(&pr->pr_mtx);
-	KASSERT(pr->pr_uref > 0,
-	    ("Cannot add a process to a non-alive prison (jid=%d)", pr->pr_id));
-	pr->pr_uref++;
-	mtx_unlock(&pr->pr_mtx);
-}
-
-void
-prison_proc_free(struct prison *pr)
-{
-
-	mtx_lock(&pr->pr_mtx);
-	KASSERT(pr->pr_uref > 0,
-	    ("Trying to kill a process in a dead prison (jid=%d)", pr->pr_id));
-	if (pr->pr_uref > 1)
-		pr->pr_uref--;
-	else {
-		/*
-		 * Don't remove the last user reference in this context, which
-		 * is expected to be a process that is not only locked, but
-		 * also half dead.
-		 */
-		pr->pr_ref++;
-		mtx_unlock(&pr->pr_mtx);
-		taskqueue_enqueue(taskqueue_thread, &pr->pr_task);
-		return;
-	}
-	mtx_unlock(&pr->pr_mtx);
-}
-
 /*
  * Set or clear a permission bit in the pr_allow field, passing restrictions
  * (cleared permission) down to child jails.
  */
 void
 prison_set_allow(struct ucred *cred, unsigned flag, int enable)
 {
 	struct prison *pr;
 
 	pr = cred->cr_prison;
 	sx_slock(&allprison_lock);
 	mtx_lock(&pr->pr_mtx);
 	prison_set_allow_locked(pr, flag, enable);
 	mtx_unlock(&pr->pr_mtx);
 	sx_sunlock(&allprison_lock);
 }
 
 static void
 prison_set_allow_locked(struct prison *pr, unsigned flag, int enable)
 {
 	struct prison *cpr;
 	int descend;
 
 	if (enable != 0)
 		pr->pr_allow |= flag;
 	else {
 		pr->pr_allow &= ~flag;
 		FOREACH_PRISON_DESCENDANT_LOCKED(pr, cpr, descend)
 			cpr->pr_allow &= ~flag;
 	}
 }
 
 /*
  * Check if a jail supports the given address family.
  *
  * Returns 0 if not jailed or the address family is supported, EAFNOSUPPORT
  * if not.
  */
 int
 prison_check_af(struct ucred *cred, int af)
 {
 	struct prison *pr;
 	int error;
 
 	KASSERT(cred != NULL, ("%s: cred is NULL", __func__));
 
 	pr = cred->cr_prison;
 #ifdef VIMAGE
 	/* Prisons with their own network stack are not limited. */
 	if (prison_owns_vnet(cred))
 		return (0);
 #endif
 
 	error = 0;
 	switch (af)
 	{
 #ifdef INET
 	case AF_INET:
 		if (pr->pr_flags & PR_IP4)
 		{
 			mtx_lock(&pr->pr_mtx);
 			if ((pr->pr_flags & PR_IP4) && pr->pr_ip4 == NULL)
 				error = EAFNOSUPPORT;
 			mtx_unlock(&pr->pr_mtx);
 		}
 		break;
 #endif
 #ifdef INET6
 	case AF_INET6:
 		if (pr->pr_flags & PR_IP6)
 		{
 			mtx_lock(&pr->pr_mtx);
 			if ((pr->pr_flags & PR_IP6) && pr->pr_ip6 == NULL)
 				error = EAFNOSUPPORT;
 			mtx_unlock(&pr->pr_mtx);
 		}
 		break;
 #endif
 	case AF_LOCAL:
 	case AF_ROUTE:
 		break;
 	default:
 		if (!(pr->pr_allow & PR_ALLOW_SOCKET_AF))
 			error = EAFNOSUPPORT;
 	}
 	return (error);
 }
 
 /*
  * Check if given address belongs to the jail referenced by cred (wrapper to
  * prison_check_ip[46]).
  *
  * Returns 0 if jail doesn't restrict the address family or if address belongs
  * to jail, EADDRNOTAVAIL if the address doesn't belong, or EAFNOSUPPORT if
  * the jail doesn't allow the address family.  IPv4 Address passed in in NBO.
  */
 int
 prison_if(struct ucred *cred, const struct sockaddr *sa)
 {
 #ifdef INET
 	const struct sockaddr_in *sai;
 #endif
 #ifdef INET6
 	const struct sockaddr_in6 *sai6;
 #endif
 	int error;
 
 	KASSERT(cred != NULL, ("%s: cred is NULL", __func__));
 	KASSERT(sa != NULL, ("%s: sa is NULL", __func__));
 
 #ifdef VIMAGE
 	if (prison_owns_vnet(cred))
 		return (0);
 #endif
 
 	error = 0;
 	switch (sa->sa_family)
 	{
 #ifdef INET
 	case AF_INET:
 		sai = (const struct sockaddr_in *)sa;
 		error = prison_check_ip4(cred, &sai->sin_addr);
 		break;
 #endif
 #ifdef INET6
 	case AF_INET6:
 		sai6 = (const struct sockaddr_in6 *)sa;
 		error = prison_check_ip6(cred, &sai6->sin6_addr);
 		break;
 #endif
 	default:
 		if (!(cred->cr_prison->pr_allow & PR_ALLOW_SOCKET_AF))
 			error = EAFNOSUPPORT;
 	}
 	return (error);
 }
 
 /*
  * Return 0 if jails permit p1 to frob p2, otherwise ESRCH.
  */
 int
 prison_check(struct ucred *cred1, struct ucred *cred2)
 {
 
 	return ((cred1->cr_prison == cred2->cr_prison ||
 	    prison_ischild(cred1->cr_prison, cred2->cr_prison)) ? 0 : ESRCH);
 }
 
 /*
  * Return 1 if p2 is a child of p1, otherwise 0.
  */
 int
 prison_ischild(struct prison *pr1, struct prison *pr2)
 {
 
 	for (pr2 = pr2->pr_parent; pr2 != NULL; pr2 = pr2->pr_parent)
 		if (pr1 == pr2)
 			return (1);
 	return (0);
 }
 
 /*
  * Return true if the prison is currently alive.  A prison is alive if it is
  * valid and it holds user references.
  */
 bool
 prison_isalive(struct prison *pr)
 {
 
 	mtx_assert(&pr->pr_mtx, MA_OWNED);
 	if (__predict_false(pr->pr_ref == 0))
 		return (false);
 	if (__predict_false(pr->pr_uref == 0))
 		return (false);
 	return (true);
 }
 
 /*
  * Return true if the prison is currently valid.  A prison is valid if it has
  * been fully created, and is not being destroyed.  Note that dying prisons
  * are still considered valid.
  */
 bool
 prison_isvalid(struct prison *pr)
 {
 
 	mtx_assert(&pr->pr_mtx, MA_OWNED);
 	if (__predict_false(pr->pr_ref == 0))
 		return (false);
 	return (true);
 }
 
 /*
  * Return 1 if the passed credential is in a jail and that jail does not
  * have its own virtual network stack, otherwise 0.
  */
 int
 jailed_without_vnet(struct ucred *cred)
 {
 
 	if (!jailed(cred))
 		return (0);
 #ifdef VIMAGE
 	if (prison_owns_vnet(cred))
 		return (0);
 #endif
 
 	return (1);
 }
 
 /*
  * Return the correct hostname (domainname, et al) for the passed credential.
  */
 void
 getcredhostname(struct ucred *cred, char *buf, size_t size)
 {
 	struct prison *pr;
 
 	/*
 	 * A NULL credential can be used to shortcut to the physical
 	 * system's hostname.
 	 */
 	pr = (cred != NULL) ? cred->cr_prison : &prison0;
 	mtx_lock(&pr->pr_mtx);
 	strlcpy(buf, pr->pr_hostname, size);
 	mtx_unlock(&pr->pr_mtx);
 }
 
 void
 getcreddomainname(struct ucred *cred, char *buf, size_t size)
 {
 
 	mtx_lock(&cred->cr_prison->pr_mtx);
 	strlcpy(buf, cred->cr_prison->pr_domainname, size);
 	mtx_unlock(&cred->cr_prison->pr_mtx);
 }
 
 void
 getcredhostuuid(struct ucred *cred, char *buf, size_t size)
 {
 
 	mtx_lock(&cred->cr_prison->pr_mtx);
 	strlcpy(buf, cred->cr_prison->pr_hostuuid, size);
 	mtx_unlock(&cred->cr_prison->pr_mtx);
 }
 
 void
 getcredhostid(struct ucred *cred, unsigned long *hostid)
 {
 
 	mtx_lock(&cred->cr_prison->pr_mtx);
 	*hostid = cred->cr_prison->pr_hostid;
 	mtx_unlock(&cred->cr_prison->pr_mtx);
 }
 
 void
 getjailname(struct ucred *cred, char *name, size_t len)
 {
 
 	mtx_lock(&cred->cr_prison->pr_mtx);
 	strlcpy(name, cred->cr_prison->pr_name, len);
 	mtx_unlock(&cred->cr_prison->pr_mtx);
 }
 
 #ifdef VIMAGE
 /*
  * Determine whether the prison represented by cred owns
  * its vnet rather than having it inherited.
  *
  * Returns 1 in case the prison owns the vnet, 0 otherwise.
  */
 int
 prison_owns_vnet(struct ucred *cred)
 {
 
 	/*
 	 * vnets cannot be added/removed after jail creation,
 	 * so no need to lock here.
 	 */
 	return (cred->cr_prison->pr_flags & PR_VNET ? 1 : 0);
 }
 #endif
 
 /*
  * Determine whether the subject represented by cred can "see"
  * status of a mount point.
  * Returns: 0 for permitted, ENOENT otherwise.
  * XXX: This function should be called cr_canseemount() and should be
  *      placed in kern_prot.c.
  */
 int
 prison_canseemount(struct ucred *cred, struct mount *mp)
 {
 	struct prison *pr;
 	struct statfs *sp;
 	size_t len;
 
 	pr = cred->cr_prison;
 	if (pr->pr_enforce_statfs == 0)
 		return (0);
 	if (pr->pr_root->v_mount == mp)
 		return (0);
 	if (pr->pr_enforce_statfs == 2)
 		return (ENOENT);
 	/*
 	 * If jail's chroot directory is set to "/" we should be able to see
 	 * all mount-points from inside a jail.
 	 * This is ugly check, but this is the only situation when jail's
 	 * directory ends with '/'.
 	 */
 	if (strcmp(pr->pr_path, "/") == 0)
 		return (0);
 	len = strlen(pr->pr_path);
 	sp = &mp->mnt_stat;
 	if (strncmp(pr->pr_path, sp->f_mntonname, len) != 0)
 		return (ENOENT);
 	/*
 	 * Be sure that we don't have situation where jail's root directory
 	 * is "/some/path" and mount point is "/some/pathpath".
 	 */
 	if (sp->f_mntonname[len] != '\0' && sp->f_mntonname[len] != '/')
 		return (ENOENT);
 	return (0);
 }
 
 void
 prison_enforce_statfs(struct ucred *cred, struct mount *mp, struct statfs *sp)
 {
 	char jpath[MAXPATHLEN];
 	struct prison *pr;
 	size_t len;
 
 	pr = cred->cr_prison;
 	if (pr->pr_enforce_statfs == 0)
 		return;
 	if (prison_canseemount(cred, mp) != 0) {
 		bzero(sp->f_mntonname, sizeof(sp->f_mntonname));
 		strlcpy(sp->f_mntonname, "[restricted]",
 		    sizeof(sp->f_mntonname));
 		return;
 	}
 	if (pr->pr_root->v_mount == mp) {
 		/*
 		 * Clear current buffer data, so we are sure nothing from
 		 * the valid path left there.
 		 */
 		bzero(sp->f_mntonname, sizeof(sp->f_mntonname));
 		*sp->f_mntonname = '/';
 		return;
 	}
 	/*
 	 * If jail's chroot directory is set to "/" we should be able to see
 	 * all mount-points from inside a jail.
 	 */
 	if (strcmp(pr->pr_path, "/") == 0)
 		return;
 	len = strlen(pr->pr_path);
 	strlcpy(jpath, sp->f_mntonname + len, sizeof(jpath));
 	/*
 	 * Clear current buffer data, so we are sure nothing from
 	 * the valid path left there.
 	 */
 	bzero(sp->f_mntonname, sizeof(sp->f_mntonname));
 	if (*jpath == '\0') {
 		/* Should never happen. */
 		*sp->f_mntonname = '/';
 	} else {
 		strlcpy(sp->f_mntonname, jpath, sizeof(sp->f_mntonname));
 	}
 }
 
 /*
  * Check with permission for a specific privilege is granted within jail.  We
  * have a specific list of accepted privileges; the rest are denied.
  */
 int
 prison_priv_check(struct ucred *cred, int priv)
 {
 	struct prison *pr;
 	int error;
 
 	/*
 	 * Some policies have custom handlers. This routine should not be
 	 * called for them. See priv_check_cred().
 	 */
 	switch (priv) {
 	case PRIV_VFS_LOOKUP:
 	case PRIV_VFS_GENERATION:
 		KASSERT(0, ("prison_priv_check instead of a custom handler "
 		    "called for %d\n", priv));
 	}
 
 	if (!jailed(cred))
 		return (0);
 
 #ifdef VIMAGE
 	/*
 	 * Privileges specific to prisons with a virtual network stack.
 	 * There might be a duplicate entry here in case the privilege
 	 * is only granted conditionally in the legacy jail case.
 	 */
 	switch (priv) {
 #ifdef notyet
 		/*
 		 * NFS-specific privileges.
 		 */
 	case PRIV_NFS_DAEMON:
 	case PRIV_NFS_LOCKD:
 #endif
 		/*
 		 * Network stack privileges.
 		 */
 	case PRIV_NET_BRIDGE:
 	case PRIV_NET_GRE:
 	case PRIV_NET_BPF:
 	case PRIV_NET_RAW:		/* Dup, cond. in legacy jail case. */
 	case PRIV_NET_ROUTE:
 	case PRIV_NET_TAP:
 	case PRIV_NET_SETIFMTU:
 	case PRIV_NET_SETIFFLAGS:
 	case PRIV_NET_SETIFCAP:
 	case PRIV_NET_SETIFDESCR:
 	case PRIV_NET_SETIFNAME	:
 	case PRIV_NET_SETIFMETRIC:
 	case PRIV_NET_SETIFPHYS:
 	case PRIV_NET_SETIFMAC:
 	case PRIV_NET_SETLANPCP:
 	case PRIV_NET_ADDMULTI:
 	case PRIV_NET_DELMULTI:
 	case PRIV_NET_HWIOCTL:
 	case PRIV_NET_SETLLADDR:
 	case PRIV_NET_ADDIFGROUP:
 	case PRIV_NET_DELIFGROUP:
 	case PRIV_NET_IFCREATE:
 	case PRIV_NET_IFDESTROY:
 	case PRIV_NET_ADDIFADDR:
 	case PRIV_NET_DELIFADDR:
 	case PRIV_NET_LAGG:
 	case PRIV_NET_GIF:
 	case PRIV_NET_SETIFVNET:
 	case PRIV_NET_SETIFFIB:
 
 		/*
 		 * 802.11-related privileges.
 		 */
 	case PRIV_NET80211_VAP_GETKEY:
 	case PRIV_NET80211_VAP_MANAGE:
 
 #ifdef notyet
 		/*
 		 * ATM privileges.
 		 */
 	case PRIV_NETATM_CFG:
 	case PRIV_NETATM_ADD:
 	case PRIV_NETATM_DEL:
 	case PRIV_NETATM_SET:
 
 		/*
 		 * Bluetooth privileges.
 		 */
 	case PRIV_NETBLUETOOTH_RAW:
 #endif
 
 		/*
 		 * Netgraph and netgraph module privileges.
 		 */
 	case PRIV_NETGRAPH_CONTROL:
 #ifdef notyet
 	case PRIV_NETGRAPH_TTY:
 #endif
 
 		/*
 		 * IPv4 and IPv6 privileges.
 		 */
 	case PRIV_NETINET_IPFW:
 	case PRIV_NETINET_DIVERT:
 	case PRIV_NETINET_PF:
 	case PRIV_NETINET_DUMMYNET:
 	case PRIV_NETINET_CARP:
 	case PRIV_NETINET_MROUTE:
 	case PRIV_NETINET_RAW:
 	case PRIV_NETINET_ADDRCTRL6:
 	case PRIV_NETINET_ND6:
 	case PRIV_NETINET_SCOPE6:
 	case PRIV_NETINET_ALIFETIME6:
 	case PRIV_NETINET_IPSEC:
 	case PRIV_NETINET_BINDANY:
 
 #ifdef notyet
 		/*
 		 * NCP privileges.
 		 */
 	case PRIV_NETNCP:
 
 		/*
 		 * SMB privileges.
 		 */
 	case PRIV_NETSMB:
 #endif
 
 	/*
 	 * No default: or deny here.
 	 * In case of no permit fall through to next switch().
 	 */
 		if (cred->cr_prison->pr_flags & PR_VNET)
 			return (0);
 	}
 #endif /* VIMAGE */
 
 	switch (priv) {
 		/*
 		 * Allow ktrace privileges for root in jail.
 		 */
 	case PRIV_KTRACE:
 
 #if 0
 		/*
 		 * Allow jailed processes to configure audit identity and
 		 * submit audit records (login, etc).  In the future we may
 		 * want to further refine the relationship between audit and
 		 * jail.
 		 */
 	case PRIV_AUDIT_GETAUDIT:
 	case PRIV_AUDIT_SETAUDIT:
 	case PRIV_AUDIT_SUBMIT:
 #endif
 
 		/*
 		 * Allow jailed processes to manipulate process UNIX
 		 * credentials in any way they see fit.
 		 */
 	case PRIV_CRED_SETUID:
 	case PRIV_CRED_SETEUID:
 	case PRIV_CRED_SETGID:
 	case PRIV_CRED_SETEGID:
 	case PRIV_CRED_SETGROUPS:
 	case PRIV_CRED_SETREUID:
 	case PRIV_CRED_SETREGID:
 	case PRIV_CRED_SETRESUID:
 	case PRIV_CRED_SETRESGID:
 
 		/*
 		 * Jail implements visibility constraints already, so allow
 		 * jailed root to override uid/gid-based constraints.
 		 */
 	case PRIV_SEEOTHERGIDS:
 	case PRIV_SEEOTHERUIDS:
 
 		/*
 		 * Jail implements inter-process debugging limits already, so
 		 * allow jailed root various debugging privileges.
 		 */
 	case PRIV_DEBUG_DIFFCRED:
 	case PRIV_DEBUG_SUGID:
 	case PRIV_DEBUG_UNPRIV:
 
 		/*
 		 * Allow jail to set various resource limits and login
 		 * properties, and for now, exceed process resource limits.
 		 */
 	case PRIV_PROC_LIMIT:
 	case PRIV_PROC_SETLOGIN:
 	case PRIV_PROC_SETRLIMIT:
 
 		/*
 		 * System V and POSIX IPC privileges are granted in jail.
 		 */
 	case PRIV_IPC_READ:
 	case PRIV_IPC_WRITE:
 	case PRIV_IPC_ADMIN:
 	case PRIV_IPC_MSGSIZE:
 	case PRIV_MQ_ADMIN:
 
 		/*
 		 * Jail operations within a jail work on child jails.
 		 */
 	case PRIV_JAIL_ATTACH:
 	case PRIV_JAIL_SET:
 	case PRIV_JAIL_REMOVE:
 
 		/*
 		 * Jail implements its own inter-process limits, so allow
 		 * root processes in jail to change scheduling on other
 		 * processes in the same jail.  Likewise for signalling.
 		 */
 	case PRIV_SCHED_DIFFCRED:
 	case PRIV_SCHED_CPUSET:
 	case PRIV_SIGNAL_DIFFCRED:
 	case PRIV_SIGNAL_SUGID:
 
 		/*
 		 * Allow jailed processes to write to sysctls marked as jail
 		 * writable.
 		 */
 	case PRIV_SYSCTL_WRITEJAIL:
 
 		/*
 		 * Allow root in jail to manage a variety of quota
 		 * properties.  These should likely be conditional on a
 		 * configuration option.
 		 */
 	case PRIV_VFS_GETQUOTA:
 	case PRIV_VFS_SETQUOTA:
 
 		/*
 		 * Since Jail relies on chroot() to implement file system
 		 * protections, grant many VFS privileges to root in jail.
 		 * Be careful to exclude mount-related and NFS-related
 		 * privileges.
 		 */
 	case PRIV_VFS_READ:
 	case PRIV_VFS_WRITE:
 	case PRIV_VFS_ADMIN:
 	case PRIV_VFS_EXEC:
 	case PRIV_VFS_BLOCKRESERVE:	/* XXXRW: Slightly surprising. */
 	case PRIV_VFS_CHFLAGS_DEV:
 	case PRIV_VFS_CHOWN:
 	case PRIV_VFS_CHROOT:
 	case PRIV_VFS_RETAINSUGID:
 	case PRIV_VFS_FCHROOT:
 	case PRIV_VFS_LINK:
 	case PRIV_VFS_SETGID:
 	case PRIV_VFS_STAT:
 	case PRIV_VFS_STICKYFILE:
 
 		/*
 		 * As in the non-jail case, non-root users are expected to be
 		 * able to read kernel/phyiscal memory (provided /dev/[k]mem
 		 * exists in the jail and they have permission to access it).
 		 */
 	case PRIV_KMEM_READ:
 		return (0);
 
 		/*
 		 * Depending on the global setting, allow privilege of
 		 * setting system flags.
 		 */
 	case PRIV_VFS_SYSFLAGS:
 		if (cred->cr_prison->pr_allow & PR_ALLOW_CHFLAGS)
 			return (0);
 		else
 			return (EPERM);
 
 		/*
 		 * Depending on the global setting, allow privilege of
 		 * mounting/unmounting file systems.
 		 */
 	case PRIV_VFS_MOUNT:
 	case PRIV_VFS_UNMOUNT:
 	case PRIV_VFS_MOUNT_NONUSER:
 	case PRIV_VFS_MOUNT_OWNER:
 		pr = cred->cr_prison;
 		prison_lock(pr);
 		if (pr->pr_allow & PR_ALLOW_MOUNT && pr->pr_enforce_statfs < 2)
 			error = 0;
 		else
 			error = EPERM;
 		prison_unlock(pr);
 		return (error);
 
 		/*
 		 * Jails should hold no disposition on the PRIV_VFS_READ_DIR
 		 * policy.  priv_check_cred will not specifically allow it, and
 		 * we may want a MAC policy to allow it.
 		 */
 	case PRIV_VFS_READ_DIR:
 		return (0);
 
 		/*
 		 * Conditionnaly allow locking (unlocking) physical pages
 		 * in memory.
 		 */
 	case PRIV_VM_MLOCK:
 	case PRIV_VM_MUNLOCK:
 		if (cred->cr_prison->pr_allow & PR_ALLOW_MLOCK)
 			return (0);
 		else
 			return (EPERM);
 
 		/*
 		 * Conditionally allow jailed root to bind reserved ports.
 		 */
 	case PRIV_NETINET_RESERVEDPORT:
 		if (cred->cr_prison->pr_allow & PR_ALLOW_RESERVED_PORTS)
 			return (0);
 		else
 			return (EPERM);
 
 		/*
 		 * Allow jailed root to reuse in-use ports.
 		 */
 	case PRIV_NETINET_REUSEPORT:
 		return (0);
 
 		/*
 		 * Allow jailed root to set certain IPv4/6 (option) headers.
 		 */
 	case PRIV_NETINET_SETHDROPTS:
 		return (0);
 
 		/*
 		 * Conditionally allow creating raw sockets in jail.
 		 */
 	case PRIV_NETINET_RAW:
 		if (cred->cr_prison->pr_allow & PR_ALLOW_RAW_SOCKETS)
 			return (0);
 		else
 			return (EPERM);
 
 		/*
 		 * Since jail implements its own visibility limits on netstat
 		 * sysctls, allow getcred.  This allows identd to work in
 		 * jail.
 		 */
 	case PRIV_NETINET_GETCRED:
 		return (0);
 
 		/*
 		 * Allow jailed root to set loginclass.
 		 */
 	case PRIV_PROC_SETLOGINCLASS:
 		return (0);
 
 		/*
 		 * Do not allow a process inside a jail to read the kernel
 		 * message buffer unless explicitly permitted.
 		 */
 	case PRIV_MSGBUF:
 		if (cred->cr_prison->pr_allow & PR_ALLOW_READ_MSGBUF)
 			return (0);
 		return (EPERM);
 
 	default:
 		/*
 		 * In all remaining cases, deny the privilege request.  This
 		 * includes almost all network privileges, many system
 		 * configuration privileges.
 		 */
 		return (EPERM);
 	}
 }
 
 /*
  * Return the part of pr2's name that is relative to pr1, or the whole name
  * if it does not directly follow.
  */
 
 char *
 prison_name(struct prison *pr1, struct prison *pr2)
 {
 	char *name;
 
 	/* Jails see themselves as "0" (if they see themselves at all). */
 	if (pr1 == pr2)
 		return "0";
 	name = pr2->pr_name;
 	if (prison_ischild(pr1, pr2)) {
 		/*
 		 * pr1 isn't locked (and allprison_lock may not be either)
 		 * so its length can't be counted on.  But the number of dots
 		 * can be counted on - and counted.
 		 */
 		for (; pr1 != &prison0; pr1 = pr1->pr_parent)
 			name = strchr(name, '.') + 1;
 	}
 	return (name);
 }
 
 /*
  * Return the part of pr2's path that is relative to pr1, or the whole path
  * if it does not directly follow.
  */
 static char *
 prison_path(struct prison *pr1, struct prison *pr2)
 {
 	char *path1, *path2;
 	int len1;
 
 	path1 = pr1->pr_path;
 	path2 = pr2->pr_path;
 	if (!strcmp(path1, "/"))
 		return (path2);
 	len1 = strlen(path1);
 	if (strncmp(path1, path2, len1))
 		return (path2);
 	if (path2[len1] == '\0')
 		return "/";
 	if (path2[len1] == '/')
 		return (path2 + len1);
 	return (path2);
 }
 
 /*
  * Jail-related sysctls.
  */
 static SYSCTL_NODE(_security, OID_AUTO, jail, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
     "Jails");
 
 static int
 sysctl_jail_list(SYSCTL_HANDLER_ARGS)
 {
 	struct xprison *xp;
 	struct prison *pr, *cpr;
 #ifdef INET
 	struct in_addr *ip4 = NULL;
 	int ip4s = 0;
 #endif
 #ifdef INET6
 	struct in6_addr *ip6 = NULL;
 	int ip6s = 0;
 #endif
 	int descend, error;
 
 	xp = malloc(sizeof(*xp), M_TEMP, M_WAITOK);
 	pr = req->td->td_ucred->cr_prison;
 	error = 0;
 	sx_slock(&allprison_lock);
 	FOREACH_PRISON_DESCENDANT(pr, cpr, descend) {
 #if defined(INET) || defined(INET6)
  again:
 #endif
 		mtx_lock(&cpr->pr_mtx);
 #ifdef INET
 		if (cpr->pr_ip4s > 0) {
 			if (ip4s < cpr->pr_ip4s) {
 				ip4s = cpr->pr_ip4s;
 				mtx_unlock(&cpr->pr_mtx);
 				ip4 = realloc(ip4, ip4s *
 				    sizeof(struct in_addr), M_TEMP, M_WAITOK);
 				goto again;
 			}
 			bcopy(cpr->pr_ip4, ip4,
 			    cpr->pr_ip4s * sizeof(struct in_addr));
 		}
 #endif
 #ifdef INET6
 		if (cpr->pr_ip6s > 0) {
 			if (ip6s < cpr->pr_ip6s) {
 				ip6s = cpr->pr_ip6s;
 				mtx_unlock(&cpr->pr_mtx);
 				ip6 = realloc(ip6, ip6s *
 				    sizeof(struct in6_addr), M_TEMP, M_WAITOK);
 				goto again;
 			}
 			bcopy(cpr->pr_ip6, ip6,
 			    cpr->pr_ip6s * sizeof(struct in6_addr));
 		}
 #endif
 		if (!prison_isvalid(cpr)) {
 			mtx_unlock(&cpr->pr_mtx);
 			continue;
 		}
 		bzero(xp, sizeof(*xp));
 		xp->pr_version = XPRISON_VERSION;
 		xp->pr_id = cpr->pr_id;
 		xp->pr_state = prison_isalive(cpr)
 		    ? PRISON_STATE_ALIVE : PRISON_STATE_DYING;
 		strlcpy(xp->pr_path, prison_path(pr, cpr), sizeof(xp->pr_path));
 		strlcpy(xp->pr_host, cpr->pr_hostname, sizeof(xp->pr_host));
 		strlcpy(xp->pr_name, prison_name(pr, cpr), sizeof(xp->pr_name));
 #ifdef INET
 		xp->pr_ip4s = cpr->pr_ip4s;
 #endif
 #ifdef INET6
 		xp->pr_ip6s = cpr->pr_ip6s;
 #endif
 		mtx_unlock(&cpr->pr_mtx);
 		error = SYSCTL_OUT(req, xp, sizeof(*xp));
 		if (error)
 			break;
 #ifdef INET
 		if (xp->pr_ip4s > 0) {
 			error = SYSCTL_OUT(req, ip4,
 			    xp->pr_ip4s * sizeof(struct in_addr));
 			if (error)
 				break;
 		}
 #endif
 #ifdef INET6
 		if (xp->pr_ip6s > 0) {
 			error = SYSCTL_OUT(req, ip6,
 			    xp->pr_ip6s * sizeof(struct in6_addr));
 			if (error)
 				break;
 		}
 #endif
 	}
 	sx_sunlock(&allprison_lock);
 	free(xp, M_TEMP);
 #ifdef INET
 	free(ip4, M_TEMP);
 #endif
 #ifdef INET6
 	free(ip6, M_TEMP);
 #endif
 	return (error);
 }
 
 SYSCTL_OID(_security_jail, OID_AUTO, list,
     CTLTYPE_STRUCT | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0,
     sysctl_jail_list, "S", "List of active jails");
 
 static int
 sysctl_jail_jailed(SYSCTL_HANDLER_ARGS)
 {
 	int error, injail;
 
 	injail = jailed(req->td->td_ucred);
 	error = SYSCTL_OUT(req, &injail, sizeof(injail));
 
 	return (error);
 }
 
 SYSCTL_PROC(_security_jail, OID_AUTO, jailed,
     CTLTYPE_INT | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0,
     sysctl_jail_jailed, "I", "Process in jail?");
 
 static int
 sysctl_jail_vnet(SYSCTL_HANDLER_ARGS)
 {
 	int error, havevnet;
 #ifdef VIMAGE
 	struct ucred *cred = req->td->td_ucred;
 
 	havevnet = jailed(cred) && prison_owns_vnet(cred);
 #else
 	havevnet = 0;
 #endif
 	error = SYSCTL_OUT(req, &havevnet, sizeof(havevnet));
 
 	return (error);
 }
 
 SYSCTL_PROC(_security_jail, OID_AUTO, vnet,
     CTLTYPE_INT | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0,
     sysctl_jail_vnet, "I", "Jail owns vnet?");
 
 #if defined(INET) || defined(INET6)
 SYSCTL_UINT(_security_jail, OID_AUTO, jail_max_af_ips, CTLFLAG_RW,
     &jail_max_af_ips, 0,
     "Number of IP addresses a jail may have at most per address family (deprecated)");
 #endif
 
 /*
  * Default parameters for jail(2) compatibility.  For historical reasons,
  * the sysctl names have varying similarity to the parameter names.  Prisons
  * just see their own parameters, and can't change them.
  */
 static int
 sysctl_jail_default_allow(SYSCTL_HANDLER_ARGS)
 {
 	int error, i;
 
 	/* Get the current flag value, and convert it to a boolean. */
 	if (req->td->td_ucred->cr_prison == &prison0) {
 		mtx_lock(&prison0.pr_mtx);
 		i = (jail_default_allow & arg2) != 0;
 		mtx_unlock(&prison0.pr_mtx);
 	} else
 		i = prison_allow(req->td->td_ucred, arg2);
 
 	if (arg1 != NULL)
 		i = !i;
 	error = sysctl_handle_int(oidp, &i, 0, req);
 	if (error || !req->newptr)
 		return (error);
 	i = i ? arg2 : 0;
 	if (arg1 != NULL)
 		i ^= arg2;
 	/*
 	 * The sysctls don't have CTLFLAGS_PRISON, so assume prison0
 	 * for writing.
 	 */
 	mtx_lock(&prison0.pr_mtx);
 	jail_default_allow = (jail_default_allow & ~arg2) | i;
 	mtx_unlock(&prison0.pr_mtx);
 	return (0);
 }
 
 SYSCTL_PROC(_security_jail, OID_AUTO, set_hostname_allowed,
     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
     NULL, PR_ALLOW_SET_HOSTNAME, sysctl_jail_default_allow, "I",
     "Processes in jail can set their hostnames (deprecated)");
 SYSCTL_PROC(_security_jail, OID_AUTO, socket_unixiproute_only,
     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
     (void *)1, PR_ALLOW_SOCKET_AF, sysctl_jail_default_allow, "I",
     "Processes in jail are limited to creating UNIX/IP/route sockets only (deprecated)");
 SYSCTL_PROC(_security_jail, OID_AUTO, sysvipc_allowed,
     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
     NULL, PR_ALLOW_SYSVIPC, sysctl_jail_default_allow, "I",
     "Processes in jail can use System V IPC primitives (deprecated)");
 SYSCTL_PROC(_security_jail, OID_AUTO, allow_raw_sockets,
     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
     NULL, PR_ALLOW_RAW_SOCKETS, sysctl_jail_default_allow, "I",
     "Prison root can create raw sockets (deprecated)");
 SYSCTL_PROC(_security_jail, OID_AUTO, chflags_allowed,
     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
     NULL, PR_ALLOW_CHFLAGS, sysctl_jail_default_allow, "I",
     "Processes in jail can alter system file flags (deprecated)");
 SYSCTL_PROC(_security_jail, OID_AUTO, mount_allowed,
     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
     NULL, PR_ALLOW_MOUNT, sysctl_jail_default_allow, "I",
     "Processes in jail can mount/unmount jail-friendly file systems (deprecated)");
 
 static int
 sysctl_jail_default_level(SYSCTL_HANDLER_ARGS)
 {
 	struct prison *pr;
 	int level, error;
 
 	pr = req->td->td_ucred->cr_prison;
 	level = (pr == &prison0) ? *(int *)arg1 : *(int *)((char *)pr + arg2);
 	error = sysctl_handle_int(oidp, &level, 0, req);
 	if (error || !req->newptr)
 		return (error);
 	*(int *)arg1 = level;
 	return (0);
 }
 
 SYSCTL_PROC(_security_jail, OID_AUTO, enforce_statfs,
     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
     &jail_default_enforce_statfs, offsetof(struct prison, pr_enforce_statfs),
     sysctl_jail_default_level, "I",
     "Processes in jail cannot see all mounted file systems (deprecated)");
 
 SYSCTL_PROC(_security_jail, OID_AUTO, devfs_ruleset,
     CTLTYPE_INT | CTLFLAG_RD | CTLFLAG_MPSAFE,
     &jail_default_devfs_rsnum, offsetof(struct prison, pr_devfs_rsnum),
     sysctl_jail_default_level, "I",
     "Ruleset for the devfs filesystem in jail (deprecated)");
 
 /*
  * Nodes to describe jail parameters.  Maximum length of string parameters
  * is returned in the string itself, and the other parameters exist merely
  * to make themselves and their types known.
  */
 SYSCTL_NODE(_security_jail, OID_AUTO, param, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
     "Jail parameters");
 
 int
 sysctl_jail_param(SYSCTL_HANDLER_ARGS)
 {
 	int i;
 	long l;
 	size_t s;
 	char numbuf[12];
 
 	switch (oidp->oid_kind & CTLTYPE)
 	{
 	case CTLTYPE_LONG:
 	case CTLTYPE_ULONG:
 		l = 0;
 #ifdef SCTL_MASK32
 		if (!(req->flags & SCTL_MASK32))
 #endif
 			return (SYSCTL_OUT(req, &l, sizeof(l)));
 	case CTLTYPE_INT:
 	case CTLTYPE_UINT:
 		i = 0;
 		return (SYSCTL_OUT(req, &i, sizeof(i)));
 	case CTLTYPE_STRING:
 		snprintf(numbuf, sizeof(numbuf), "%jd", (intmax_t)arg2);
 		return
 		    (sysctl_handle_string(oidp, numbuf, sizeof(numbuf), req));
 	case CTLTYPE_STRUCT:
 		s = (size_t)arg2;
 		return (SYSCTL_OUT(req, &s, sizeof(s)));
 	}
 	return (0);
 }
 
 /*
  * CTLFLAG_RDTUN in the following indicates jail parameters that can be set at
  * jail creation time but cannot be changed in an existing jail.
  */
 SYSCTL_JAIL_PARAM(, jid, CTLTYPE_INT | CTLFLAG_RDTUN, "I", "Jail ID");
 SYSCTL_JAIL_PARAM(, parent, CTLTYPE_INT | CTLFLAG_RD, "I", "Jail parent ID");
 SYSCTL_JAIL_PARAM_STRING(, name, CTLFLAG_RW, MAXHOSTNAMELEN, "Jail name");
 SYSCTL_JAIL_PARAM_STRING(, path, CTLFLAG_RDTUN, MAXPATHLEN, "Jail root path");
 SYSCTL_JAIL_PARAM(, securelevel, CTLTYPE_INT | CTLFLAG_RW,
     "I", "Jail secure level");
 SYSCTL_JAIL_PARAM(, osreldate, CTLTYPE_INT | CTLFLAG_RDTUN, "I",
     "Jail value for kern.osreldate and uname -K");
 SYSCTL_JAIL_PARAM_STRING(, osrelease, CTLFLAG_RDTUN, OSRELEASELEN,
     "Jail value for kern.osrelease and uname -r");
 SYSCTL_JAIL_PARAM(, enforce_statfs, CTLTYPE_INT | CTLFLAG_RW,
     "I", "Jail cannot see all mounted file systems");
 SYSCTL_JAIL_PARAM(, devfs_ruleset, CTLTYPE_INT | CTLFLAG_RW,
     "I", "Ruleset for in-jail devfs mounts");
 SYSCTL_JAIL_PARAM(, persist, CTLTYPE_INT | CTLFLAG_RW,
     "B", "Jail persistence");
 #ifdef VIMAGE
 SYSCTL_JAIL_PARAM(, vnet, CTLTYPE_INT | CTLFLAG_RDTUN,
     "E,jailsys", "Virtual network stack");
 #endif
 SYSCTL_JAIL_PARAM(, dying, CTLTYPE_INT | CTLFLAG_RD,
     "B", "Jail is in the process of shutting down");
 
 SYSCTL_JAIL_PARAM_NODE(children, "Number of child jails");
 SYSCTL_JAIL_PARAM(_children, cur, CTLTYPE_INT | CTLFLAG_RD,
     "I", "Current number of child jails");
 SYSCTL_JAIL_PARAM(_children, max, CTLTYPE_INT | CTLFLAG_RW,
     "I", "Maximum number of child jails");
 
 SYSCTL_JAIL_PARAM_SYS_NODE(host, CTLFLAG_RW, "Jail host info");
 SYSCTL_JAIL_PARAM_STRING(_host, hostname, CTLFLAG_RW, MAXHOSTNAMELEN,
     "Jail hostname");
 SYSCTL_JAIL_PARAM_STRING(_host, domainname, CTLFLAG_RW, MAXHOSTNAMELEN,
     "Jail NIS domainname");
 SYSCTL_JAIL_PARAM_STRING(_host, hostuuid, CTLFLAG_RW, HOSTUUIDLEN,
     "Jail host UUID");
 SYSCTL_JAIL_PARAM(_host, hostid, CTLTYPE_ULONG | CTLFLAG_RW,
     "LU", "Jail host ID");
 
 SYSCTL_JAIL_PARAM_NODE(cpuset, "Jail cpuset");
 SYSCTL_JAIL_PARAM(_cpuset, id, CTLTYPE_INT | CTLFLAG_RD, "I", "Jail cpuset ID");
 
 #ifdef INET
 SYSCTL_JAIL_PARAM_SYS_NODE(ip4, CTLFLAG_RDTUN,
     "Jail IPv4 address virtualization");
 SYSCTL_JAIL_PARAM_STRUCT(_ip4, addr, CTLFLAG_RW, sizeof(struct in_addr),
     "S,in_addr,a", "Jail IPv4 addresses");
 SYSCTL_JAIL_PARAM(_ip4, saddrsel, CTLTYPE_INT | CTLFLAG_RW,
     "B", "Do (not) use IPv4 source address selection rather than the "
     "primary jail IPv4 address.");
 #endif
 #ifdef INET6
 SYSCTL_JAIL_PARAM_SYS_NODE(ip6, CTLFLAG_RDTUN,
     "Jail IPv6 address virtualization");
 SYSCTL_JAIL_PARAM_STRUCT(_ip6, addr, CTLFLAG_RW, sizeof(struct in6_addr),
     "S,in6_addr,a", "Jail IPv6 addresses");
 SYSCTL_JAIL_PARAM(_ip6, saddrsel, CTLTYPE_INT | CTLFLAG_RW,
     "B", "Do (not) use IPv6 source address selection rather than the "
     "primary jail IPv6 address.");
 #endif
 
 SYSCTL_JAIL_PARAM_NODE(allow, "Jail permission flags");
 SYSCTL_JAIL_PARAM(_allow, set_hostname, CTLTYPE_INT | CTLFLAG_RW,
     "B", "Jail may set hostname");
 SYSCTL_JAIL_PARAM(_allow, sysvipc, CTLTYPE_INT | CTLFLAG_RW,
     "B", "Jail may use SYSV IPC");
 SYSCTL_JAIL_PARAM(_allow, raw_sockets, CTLTYPE_INT | CTLFLAG_RW,
     "B", "Jail may create raw sockets");
 SYSCTL_JAIL_PARAM(_allow, chflags, CTLTYPE_INT | CTLFLAG_RW,
     "B", "Jail may alter system file flags");
 SYSCTL_JAIL_PARAM(_allow, quotas, CTLTYPE_INT | CTLFLAG_RW,
     "B", "Jail may set file quotas");
 SYSCTL_JAIL_PARAM(_allow, socket_af, CTLTYPE_INT | CTLFLAG_RW,
     "B", "Jail may create sockets other than just UNIX/IPv4/IPv6/route");
 SYSCTL_JAIL_PARAM(_allow, mlock, CTLTYPE_INT | CTLFLAG_RW,
     "B", "Jail may lock (unlock) physical pages in memory");
 SYSCTL_JAIL_PARAM(_allow, reserved_ports, CTLTYPE_INT | CTLFLAG_RW,
     "B", "Jail may bind sockets to reserved ports");
 SYSCTL_JAIL_PARAM(_allow, read_msgbuf, CTLTYPE_INT | CTLFLAG_RW,
     "B", "Jail may read the kernel message buffer");
 SYSCTL_JAIL_PARAM(_allow, unprivileged_proc_debug, CTLTYPE_INT | CTLFLAG_RW,
     "B", "Unprivileged processes may use process debugging facilities");
 SYSCTL_JAIL_PARAM(_allow, suser, CTLTYPE_INT | CTLFLAG_RW,
     "B", "Processes in jail with uid 0 have privilege");
 
 SYSCTL_JAIL_PARAM_SUBNODE(allow, mount, "Jail mount/unmount permission flags");
 SYSCTL_JAIL_PARAM(_allow_mount, , CTLTYPE_INT | CTLFLAG_RW,
     "B", "Jail may mount/unmount jail-friendly file systems in general");
 
 /*
  * Add a dynamic parameter allow.<name>, or allow.<prefix>.<name>.  Return
  * its associated bit in the pr_allow bitmask, or zero if the parameter was
  * not created.
  */
 unsigned
 prison_add_allow(const char *prefix, const char *name, const char *prefix_descr,
     const char *descr)
 {
 	struct bool_flags *bf;
 	struct sysctl_oid *parent;
 	char *allow_name, *allow_noname, *allowed;
 #ifndef NO_SYSCTL_DESCR
 	char *descr_deprecated;
 #endif
 	u_int allow_flag;
 
 	if (prefix
 	    ? asprintf(&allow_name, M_PRISON, "allow.%s.%s", prefix, name)
 		< 0 ||
 	      asprintf(&allow_noname, M_PRISON, "allow.%s.no%s", prefix, name)
 		< 0
 	    : asprintf(&allow_name, M_PRISON, "allow.%s", name) < 0 ||
 	      asprintf(&allow_noname, M_PRISON, "allow.no%s", name) < 0) {
 		free(allow_name, M_PRISON);
 		return 0;
 	}
 
 	/*
 	 * See if this parameter has already beed added, i.e. a module was
 	 * previously loaded/unloaded.
 	 */
 	mtx_lock(&prison0.pr_mtx);
 	for (bf = pr_flag_allow;
 	     bf < pr_flag_allow + nitems(pr_flag_allow) &&
 		atomic_load_int(&bf->flag) != 0;
 	     bf++) {
 		if (strcmp(bf->name, allow_name) == 0) {
 			allow_flag = bf->flag;
 			goto no_add;
 		}
 	}
 
 	/*
 	 * Find a free bit in pr_allow_all, failing if there are none
 	 * (which shouldn't happen as long as we keep track of how many
 	 * potential dynamic flags exist).
 	 */
 	for (allow_flag = 1;; allow_flag <<= 1) {
 		if (allow_flag == 0)
 			goto no_add;
 		if ((pr_allow_all & allow_flag) == 0)
 			break;
 	}
 
 	/* Note the parameter in the next open slot in pr_flag_allow. */
 	for (bf = pr_flag_allow; ; bf++) {
 		if (bf == pr_flag_allow + nitems(pr_flag_allow)) {
 			/* This should never happen, but is not fatal. */
 			allow_flag = 0;
 			goto no_add;
 		}
 		if (atomic_load_int(&bf->flag) == 0)
 			break;
 	}
 	bf->name = allow_name;
 	bf->noname = allow_noname;
 	pr_allow_all |= allow_flag;
 	/*
 	 * prison0 always has permission for the new parameter.
 	 * Other jails must have it granted to them.
 	 */
 	prison0.pr_allow |= allow_flag;
 	/* The flag indicates a valid entry, so make sure it is set last. */
 	atomic_store_rel_int(&bf->flag, allow_flag);
 	mtx_unlock(&prison0.pr_mtx);
 
 	/*
 	 * Create sysctls for the paramter, and the back-compat global
 	 * permission.
 	 */
 	parent = prefix
 	    ? SYSCTL_ADD_NODE(NULL,
 		  SYSCTL_CHILDREN(&sysctl___security_jail_param_allow),
 		  OID_AUTO, prefix, CTLFLAG_MPSAFE, 0, prefix_descr)
 	    : &sysctl___security_jail_param_allow;
 	(void)SYSCTL_ADD_PROC(NULL, SYSCTL_CHILDREN(parent), OID_AUTO,
 	    name, CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
 	    NULL, 0, sysctl_jail_param, "B", descr);
 	if ((prefix
 	     ? asprintf(&allowed, M_TEMP, "%s_%s_allowed", prefix, name)
 	     : asprintf(&allowed, M_TEMP, "%s_allowed", name)) >= 0) {
 #ifndef NO_SYSCTL_DESCR
 		(void)asprintf(&descr_deprecated, M_TEMP, "%s (deprecated)",
 		    descr);
 #endif
 		(void)SYSCTL_ADD_PROC(NULL,
 		    SYSCTL_CHILDREN(&sysctl___security_jail), OID_AUTO, allowed,
 		    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, allow_flag,
 		    sysctl_jail_default_allow, "I", descr_deprecated);
 #ifndef NO_SYSCTL_DESCR
 		free(descr_deprecated, M_TEMP);
 #endif
 		free(allowed, M_TEMP);
 	}
 	return allow_flag;
 
  no_add:
 	mtx_unlock(&prison0.pr_mtx);
 	free(allow_name, M_PRISON);
 	free(allow_noname, M_PRISON);
 	return allow_flag;
 }
 
 /*
  * The VFS system will register jail-aware filesystems here.  They each get
  * a parameter allow.mount.xxxfs and a flag to check when a jailed user
  * attempts to mount.
  */
 void
 prison_add_vfs(struct vfsconf *vfsp)
 {
 #ifdef NO_SYSCTL_DESCR
 
 	vfsp->vfc_prison_flag = prison_add_allow("mount", vfsp->vfc_name,
 	    NULL, NULL);
 #else
 	char *descr;
 
 	(void)asprintf(&descr, M_TEMP, "Jail may mount the %s file system",
 	    vfsp->vfc_name);
 	vfsp->vfc_prison_flag = prison_add_allow("mount", vfsp->vfc_name,
 	    NULL, descr);
 	free(descr, M_TEMP);
 #endif
 }
 
 #ifdef RACCT
 void
 prison_racct_foreach(void (*callback)(struct racct *racct,
     void *arg2, void *arg3), void (*pre)(void), void (*post)(void),
     void *arg2, void *arg3)
 {
 	struct prison_racct *prr;
 
 	ASSERT_RACCT_ENABLED();
 
 	sx_slock(&allprison_lock);
 	if (pre != NULL)
 		(pre)();
 	LIST_FOREACH(prr, &allprison_racct, prr_next)
 		(callback)(prr->prr_racct, arg2, arg3);
 	if (post != NULL)
 		(post)();
 	sx_sunlock(&allprison_lock);
 }
 
 static struct prison_racct *
 prison_racct_find_locked(const char *name)
 {
 	struct prison_racct *prr;
 
 	ASSERT_RACCT_ENABLED();
 	sx_assert(&allprison_lock, SA_XLOCKED);
 
 	if (name[0] == '\0' || strlen(name) >= MAXHOSTNAMELEN)
 		return (NULL);
 
 	LIST_FOREACH(prr, &allprison_racct, prr_next) {
 		if (strcmp(name, prr->prr_name) != 0)
 			continue;
 
 		/* Found prison_racct with a matching name? */
 		prison_racct_hold(prr);
 		return (prr);
 	}
 
 	/* Add new prison_racct. */
 	prr = malloc(sizeof(*prr), M_PRISON_RACCT, M_ZERO | M_WAITOK);
 	racct_create(&prr->prr_racct);
 
 	strcpy(prr->prr_name, name);
 	refcount_init(&prr->prr_refcount, 1);
 	LIST_INSERT_HEAD(&allprison_racct, prr, prr_next);
 
 	return (prr);
 }
 
 struct prison_racct *
 prison_racct_find(const char *name)
 {
 	struct prison_racct *prr;
 
 	ASSERT_RACCT_ENABLED();
 
 	sx_xlock(&allprison_lock);
 	prr = prison_racct_find_locked(name);
 	sx_xunlock(&allprison_lock);
 	return (prr);
 }
 
 void
 prison_racct_hold(struct prison_racct *prr)
 {
 
 	ASSERT_RACCT_ENABLED();
 
 	refcount_acquire(&prr->prr_refcount);
 }
 
 static void
 prison_racct_free_locked(struct prison_racct *prr)
 {
 
 	ASSERT_RACCT_ENABLED();
 	sx_assert(&allprison_lock, SA_XLOCKED);
 
 	if (refcount_release(&prr->prr_refcount)) {
 		racct_destroy(&prr->prr_racct);
 		LIST_REMOVE(prr, prr_next);
 		free(prr, M_PRISON_RACCT);
 	}
 }
 
 void
 prison_racct_free(struct prison_racct *prr)
 {
 
 	ASSERT_RACCT_ENABLED();
 	sx_assert(&allprison_lock, SA_UNLOCKED);
 
 	if (refcount_release_if_not_last(&prr->prr_refcount))
 		return;
 
 	sx_xlock(&allprison_lock);
 	prison_racct_free_locked(prr);
 	sx_xunlock(&allprison_lock);
 }
 
 static void
 prison_racct_attach(struct prison *pr)
 {
 	struct prison_racct *prr;
 
 	ASSERT_RACCT_ENABLED();
 	sx_assert(&allprison_lock, SA_XLOCKED);
 
 	prr = prison_racct_find_locked(pr->pr_name);
 	KASSERT(prr != NULL, ("cannot find prison_racct"));
 
 	pr->pr_prison_racct = prr;
 }
 
 /*
  * Handle jail renaming.  From the racct point of view, renaming means
  * moving from one prison_racct to another.
  */
 static void
 prison_racct_modify(struct prison *pr)
 {
 #ifdef RCTL
 	struct proc *p;
 	struct ucred *cred;
 #endif
 	struct prison_racct *oldprr;
 
 	ASSERT_RACCT_ENABLED();
 
 	sx_slock(&allproc_lock);
 	sx_xlock(&allprison_lock);
 
 	if (strcmp(pr->pr_name, pr->pr_prison_racct->prr_name) == 0) {
 		sx_xunlock(&allprison_lock);
 		sx_sunlock(&allproc_lock);
 		return;
 	}
 
 	oldprr = pr->pr_prison_racct;
 	pr->pr_prison_racct = NULL;
 
 	prison_racct_attach(pr);
 
 	/*
 	 * Move resource utilisation records.
 	 */
 	racct_move(pr->pr_prison_racct->prr_racct, oldprr->prr_racct);
 
 #ifdef RCTL
 	/*
 	 * Force rctl to reattach rules to processes.
 	 */
 	FOREACH_PROC_IN_SYSTEM(p) {
 		PROC_LOCK(p);
 		cred = crhold(p->p_ucred);
 		PROC_UNLOCK(p);
 		rctl_proc_ucred_changed(p, cred);
 		crfree(cred);
 	}
 #endif
 
 	sx_sunlock(&allproc_lock);
 	prison_racct_free_locked(oldprr);
 	sx_xunlock(&allprison_lock);
 }
 
 static void
 prison_racct_detach(struct prison *pr)
 {
 
 	ASSERT_RACCT_ENABLED();
 	sx_assert(&allprison_lock, SA_UNLOCKED);
 
 	if (pr->pr_prison_racct == NULL)
 		return;
 	prison_racct_free(pr->pr_prison_racct);
 	pr->pr_prison_racct = NULL;
 }
 #endif /* RACCT */
 
 #ifdef DDB
 
 static void
 db_show_prison(struct prison *pr)
 {
 	struct bool_flags *bf;
 	struct jailsys_flags *jsf;
 #if defined(INET) || defined(INET6)
 	int ii;
 #endif
 	unsigned f;
 #ifdef INET
 	char ip4buf[INET_ADDRSTRLEN];
 #endif
 #ifdef INET6
 	char ip6buf[INET6_ADDRSTRLEN];
 #endif
 
 	db_printf("prison %p:\n", pr);
 	db_printf(" jid             = %d\n", pr->pr_id);
 	db_printf(" name            = %s\n", pr->pr_name);
 	db_printf(" parent          = %p\n", pr->pr_parent);
 	db_printf(" ref             = %d\n", pr->pr_ref);
 	db_printf(" uref            = %d\n", pr->pr_uref);
 	db_printf(" path            = %s\n", pr->pr_path);
 	db_printf(" cpuset          = %d\n", pr->pr_cpuset
 	    ? pr->pr_cpuset->cs_id : -1);
 #ifdef VIMAGE
 	db_printf(" vnet            = %p\n", pr->pr_vnet);
 #endif
 	db_printf(" root            = %p\n", pr->pr_root);
 	db_printf(" securelevel     = %d\n", pr->pr_securelevel);
 	db_printf(" devfs_rsnum     = %d\n", pr->pr_devfs_rsnum);
 	db_printf(" children.max    = %d\n", pr->pr_childmax);
 	db_printf(" children.cur    = %d\n", pr->pr_childcount);
 	db_printf(" child           = %p\n", LIST_FIRST(&pr->pr_children));
 	db_printf(" sibling         = %p\n", LIST_NEXT(pr, pr_sibling));
 	db_printf(" flags           = 0x%x", pr->pr_flags);
 	for (bf = pr_flag_bool; bf < pr_flag_bool + nitems(pr_flag_bool); bf++)
 		if (pr->pr_flags & bf->flag)
 			db_printf(" %s", bf->name);
 	for (jsf = pr_flag_jailsys;
 	     jsf < pr_flag_jailsys + nitems(pr_flag_jailsys);
 	     jsf++) {
 		f = pr->pr_flags & (jsf->disable | jsf->new);
 		db_printf(" %-16s= %s\n", jsf->name,
 		    (f != 0 && f == jsf->disable) ? "disable"
 		    : (f == jsf->new) ? "new"
 		    : "inherit");
 	}
 	db_printf(" allow           = 0x%x", pr->pr_allow);
 	for (bf = pr_flag_allow;
 	     bf < pr_flag_allow + nitems(pr_flag_allow) &&
 		atomic_load_int(&bf->flag) != 0;
 	     bf++)
 		if (pr->pr_allow & bf->flag)
 			db_printf(" %s", bf->name);
 	db_printf("\n");
 	db_printf(" enforce_statfs  = %d\n", pr->pr_enforce_statfs);
 	db_printf(" host.hostname   = %s\n", pr->pr_hostname);
 	db_printf(" host.domainname = %s\n", pr->pr_domainname);
 	db_printf(" host.hostuuid   = %s\n", pr->pr_hostuuid);
 	db_printf(" host.hostid     = %lu\n", pr->pr_hostid);
 #ifdef INET
 	db_printf(" ip4s            = %d\n", pr->pr_ip4s);
 	for (ii = 0; ii < pr->pr_ip4s; ii++)
 		db_printf(" %s %s\n",
 		    ii == 0 ? "ip4.addr        =" : "                 ",
 		    inet_ntoa_r(pr->pr_ip4[ii], ip4buf));
 #endif
 #ifdef INET6
 	db_printf(" ip6s            = %d\n", pr->pr_ip6s);
 	for (ii = 0; ii < pr->pr_ip6s; ii++)
 		db_printf(" %s %s\n",
 		    ii == 0 ? "ip6.addr        =" : "                 ",
 		    ip6_sprintf(ip6buf, &pr->pr_ip6[ii]));
 #endif
 }
 
 DB_SHOW_COMMAND(prison, db_show_prison_command)
 {
 	struct prison *pr;
 
 	if (!have_addr) {
 		/*
 		 * Show all prisons in the list, and prison0 which is not
 		 * listed.
 		 */
 		db_show_prison(&prison0);
 		if (!db_pager_quit) {
 			TAILQ_FOREACH(pr, &allprison, pr_list) {
 				db_show_prison(pr);
 				if (db_pager_quit)
 					break;
 			}
 		}
 		return;
 	}
 
 	if (addr == 0)
 		pr = &prison0;
 	else {
 		/* Look for a prison with the ID and with references. */
 		TAILQ_FOREACH(pr, &allprison, pr_list)
 			if (pr->pr_id == addr && pr->pr_ref > 0)
 				break;
 		if (pr == NULL)
 			/* Look again, without requiring a reference. */
 			TAILQ_FOREACH(pr, &allprison, pr_list)
 				if (pr->pr_id == addr)
 					break;
 		if (pr == NULL)
 			/* Assume address points to a valid prison. */
 			pr = (struct prison *)addr;
 	}
 	db_show_prison(pr);
 }
 
 #endif /* DDB */