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JAIL(2)			  FreeBSD System Calls Manual		       JAIL(2)

NAME
     jail, jail_get, jail_set, jail_remove, jail_attach	-- create and manage
     system jails

LIBRARY
     Standard C	Library	(libc, -lc)

SYNOPSIS
     #include <sys/param.h>
     #include <sys/jail.h>

     int
     jail(struct jail *jail);

     int
     jail_attach(int jid);

     int
     jail_remove(int jid);

     #include <sys/uio.h>

     int
     jail_get(struct iovec *iov, u_int niov, int flags);

     int
     jail_set(struct iovec *iov, u_int niov, int flags);

DESCRIPTION
     The jail()	system call sets up a jail and locks the current process in
     it.

     The argument is a pointer to a structure describing the prison:

	   struct jail {
		   uint32_t	   version;
		   char		   *path;
		   char		   *hostname;
		   char		   *jailname;
		   unsigned int	   ip4s;
		   unsigned int	   ip6s;
		   struct in_addr  *ip4;
		   struct in6_addr *ip6;
	   };

     ``version'' defines the version of	the API	in use.	 JAIL_API_VERSION is
     defined for the current version.

     The ``path'' pointer should be set	to the directory which is to be	the
     root of the prison.

     The ``hostname'' pointer can be set to the	hostname of the	prison.	 This
     can be changed from the inside of the prison.

     The ``jailname'' pointer is an optional name that can be assigned to the
     jail for example for management purposes.

     The ``ip4s'' and ``ip6s'' give the	numbers	of IPv4	and IPv6 addresses
     that will be passed via their respective pointers.

     The ``ip4'' and ``ip6'' pointers can be set to an arrays of IPv4 and IPv6
     addresses to be assigned to the prison, or	NULL if	none.  IPv4 addresses
     must be in	network	byte order.

     This is equivalent	to the jail_set() system call (see below), with	the
     parameters	path, host.hostname, name, ip4.addr, and ip6.addr, and with
     the JAIL_ATTACH flag.

     The jail_set() system call	creates	a new jail, or modifies	an existing
     one, and optionally locks the current process in it.  Jail	parameters are
     passed as an array	of name-value pairs in the array iov, containing niov
     elements.	Parameter names	are a null-terminated string, and values may
     be	strings, integers, or other arbitrary data.  Some parameters are
     boolean, and do not have a	value (their length is zero) but are set by
     the name alone with or without a ``no'' prefix, e.g.  persist or
     nopersist.	 Any parameters	not set	will be	given default values, gener-
     ally based	on the current environment.

     Jails have	a set of core parameters, and modules can add their own	jail
     parameters.  The current set of available parameters, and their formats,
     can be retrieved via the security.jail.param sysctl MIB entry.  Notable
     parameters	include	those mentioned	in the jail() description above, as
     well as jid and name, which identify the jail being created or modified.
     See jail(8) for more information on the core jail parameters.

     The flags arguments consists of one or more of the	following flags:

     JAIL_CREATE
	     Create a new jail.	 If a jid or name parameters exists, they must
	     not refer to an existing jail.

     JAIL_UPDATE
	     Modify an existing	jail.  One of the jid or name parameters must
	     exist, and	must refer to an existing jail.	 If both JAIL_CREATE
	     and JAIL_UPDATE are set, a	jail will be created if	it does	not
	     yet exist,	and modified if	it does	exist.

     JAIL_ATTACH
	     In	addition to creating or	modifying the jail, attach the current
	     process to	it, as with the	jail_attach() system call.

     JAIL_DYING
	     Allow setting a jail that is in the process of being removed.

     The jail_get() system call	retrieves jail parameters, using the same
     name-value	list as	jail_set() in the iov and niov arguments.  The jail to
     read can be specified by either jid or name by including those parameters
     in	the list.  If they are included	but are	not intended to	be the search
     key, they should be cleared (zero and the empty string respectively).

     The special parameter lastjid can be used to retrieve a list of all
     jails.  It	will fetch the jail with the jid above and closest to the
     passed value.  The	first jail (usually but	not always jid 1) can be found
     by	passing	a lastjid of zero.

     The flags arguments consists of one or more following flags:

     JAIL_DYING
	     Allow getting a jail that is in the process of being removed.

     The jail_attach() system call attaches the	current	process	to an existing
     jail, identified by jid.

     The jail_remove() system call removes the jail identified by jid.	It
     will kill all processes belonging to the jail, and	remove any children of
     that jail.

RETURN VALUES
     If	successful, jail(), jail_set(),	and jail_get() return a	non-negative
     integer, termed the jail identifier (JID).	 They return -1	on failure,
     and set errno to indicate the error.

     The jail_attach() and jail_remove() functions return the value 0 if suc-
     cessful; otherwise	the value -1 is	returned and the global	variable errno
     is	set to indicate	the error.

ERRORS
     The jail()	system call will fail if:

     [EPERM]		This process is	not allowed to create a	jail, either
			because	it is not the super-user, or because it	would
			exceed the jail's children.max limit.

     [EFAULT]		jail points to an address outside the allocated
			address	space of the process.

     [EINVAL]		The version number of the argument is not correct.

     [EAGAIN]		No free	JID could be found.

     The jail_set() system call	will fail if:

     [EPERM]		This process is	not allowed to create a	jail, either
			because	it is not the super-user, or because it	would
			exceed the jail's children.max limit.

     [EPERM]		A jail parameter was set to a less restrictive value
			then the current environment.

     [EFAULT]		Iov, or	one of the addresses contained within it,
			points to an address outside the allocated address
			space of the process.

     [ENOENT]		The jail referred to by	a jid or name parameter	does
			not exist, and the JAIL_CREATE flag is not set.

     [ENOENT]		The jail referred to by	a jid is not accessible	by the
			process, because the process is	in a different jail.

     [EEXIST]		The jail referred to by	a jid or name parameter
			exists,	and the	JAIL_UPDATE flag is not	set.

     [EINVAL]		A supplied parameter is	the wrong size.

     [EINVAL]		A supplied parameter is	out of range.

     [EINVAL]		A supplied string parameter is not null-terminated.

     [EINVAL]		A supplied parameter name does not match any known
			parameters.

     [EINVAL]		One of the JAIL_CREATE or JAIL_UPDATE flags is not
			set.

     [ENAMETOOLONG]	A supplied string parameter is longer than allowed.

     [EAGAIN]		There are no jail IDs left.

     The jail_get() system call	will fail if:

     [EFAULT]		Iov, or	one of the addresses contained within it,
			points to an address outside the allocated address
			space of the process.

     [ENOENT]		The jail referred to by	a jid or name parameter	does
			not exist.

     [ENOENT]		The jail referred to by	a jid is not accessible	by the
			process, because the process is	in a different jail.

     [ENOENT]		The lastjid parameter is greater than the highest cur-
			rent jail ID.

     [EINVAL]		A supplied parameter is	the wrong size.

     [EINVAL]		A supplied parameter name does not match any known
			parameters.

     The jail_attach() and jail_remove() system	calls will fail	if:

     [EPERM]		A user other than the super-user attempted to attach
			to or remove a jail.

     [EINVAL]		The jail specified by jid does not exist.

     Further jail(), jail_set(), and jail_attach() call	chroot(2) internally,
     so	they can fail for all the same reasons.	 Please	consult	the chroot(2)
     manual page for details.

SEE ALSO
     chdir(2), chroot(2), jail(8)

HISTORY
     The jail()	system call appeared in	FreeBSD	4.0.  The jail_attach()	system
     call appeared in FreeBSD 5.1.  The	jail_set(), jail_get(),	and
     jail_remove() system calls	appeared in FreeBSD 8.0.

AUTHORS
     The jail feature was written by Poul-Henning Kamp for R&D Associates
     ``http://www.rndassociates.com/'' who contributed it to FreeBSD.
     James Gritton added the extensible	jail parameters	and hierarchical
     jails.

FreeBSD	10.1		       February	8, 2012			  FreeBSD 10.1

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | HISTORY | AUTHORS

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