Manual Pages  — JAIL

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, and deprecated in favor of, 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, generally based on the current environment.

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 current 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.