table of contents
JAIL(2) | 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¶
Thejail
() 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, generally 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
andJAIL_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.
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.
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 successful; otherwise the value -1 is returned and
the global variable errno is set to indicate
the error.
ERRORS¶
Thejail
() 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.
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
orJAIL_UPDATE
flags is not set. - [
ENAMETOOLONG
] - A supplied string parameter is longer than allowed.
- [
EAGAIN
] - There are no jail IDs left.
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.
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.
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¶
Thejail
() 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.
February 8, 2012 | Debian |