zones(5) Standards, Environments, and Macros zones(5)NAMEzones - Solaris application containers
DESCRIPTION
The zones facility in Solaris provides an isolated environment for run‐
ning applications. Processes running in a zone are prevented from moni‐
toring or interfering with other activity in the system. Access to
other processes, network interfaces, file systems, devices, and inter-
process communication facilities are restricted to prevent interaction
between processes in different zones.
The privileges available within a zone are restricted to prevent opera‐
tions with system-wide impact. See privileges(5).
You can configure and administer zones with the zoneadm(1M) and
zonecfg(1M) utilities. You can specify the configuration details a
zone, install file system contents including software packages into the
zone, and manage the runtime state of the zone. You can use the zlo‐
gin(1) to run commands within an active zone. You can do this without
logging in through a network-based login server such as in.rlogind(1M)
or sshd(1M).
The autobooting of zones is enabled and disabled by the zones service,
identified by the FMRI:
svc:/system/zones:default
See zoneadm(1M). Note that a zone has an autoboot property, which can
be set to true (always autoboot). However, if the zones service is dis‐
abled, autoboot will not occur, regardless of the setting of the auto‐
boot property for a given zone. See zonecfg(1M).
An alphanumeric name and numeric ID identify each active zone. Alphanu‐
meric names are configured using the zonecfg(1M) utility. Numeric IDs
are automatically assigned when the zone is booted. The zonename(1)
utility reports the current zone name, and the zoneadm(1M) utility can
be used to report the names and IDs of configured zones.
A zone can be in one of several states:
CONFIGURED Indicates that the configuration for the zone has been
completely specified and committed to stable storage.
INCOMPLETE Indicates that the zone is in the midst of being
installed or uninstalled, or was interrupted in the
midst of such a transition.
INSTALLED Indicates that the zone's configuration has been
instantiated on the system: packages have been
installed under the zone's root path.
READY Indicates that the "virtual platform" for the zone has
been established. For instance, file systems have been
mounted, devices have been configured, but no pro‐
cesses associated with the zone have been started.
RUNNING Indicates that user processes associated with the zone
application environment are running.
SHUTTING_DOWN Indicates that the zone is being halted. The zone can
DOWN become stuck in one of these states if it is unable to
tear down the application environment state (such as
mounted file systems) or if some portion of the vir‐
tual platform cannot be destroyed. Such cases require
operator intervention.
Process Access Restrictions
Processes running inside a zone (aside from the global zone) have
restricted access to other processes. Only processes in the same zone
are visible through /proc (see proc(4) or through system call inter‐
faces that take process IDs such as kill(2) and priocntl(2). Attempts
to access processes that exist in other zones (including the global
zone) fail with the same error code that would be issued if the speci‐
fied process did not exist.
Privilege Restrictions
Processes running within a non-global zone are restricted to a subset
of privileges, in order to prevent one zone from being able to perform
operations that might affect other zones. The set of privileges limits
the capabilities of privileged users (such as the super-user or root
user) within the zone. The list of privileges available within a zone
can be displayed using the ppriv(1) utility. For more information about
privileges, see privileges(5).
Device Restrictions
The set of devices available within a zone is restricted, to prevent a
process in one zone from interfering with processes in other zones. For
example, a process in a zone should not be able to modify kernel memory
using /dev/kmem, or modify the contents of the root disk. Thus, by
default, only a few pseudo devices considered safe for use within a
zone are available. Additional devices can be made available within
specific zones using the zonecfg(1M) utility.
The device and privilege restrictions have a number of effects on the
utilities that can run in a non-global zone. For example, the eep‐
rom(1M), prtdiag(1M), and prtconf(1M) utilities do not work in a zone
since they rely on devices that are not normally available.
Brands
A zone may be assigned a brand when it is initially created. A branded
zone is one whose software does not match that software found in the
global zone. The software may include Solaris software configured or
laid out differently, or it may include non-Solaris software. The par‐
ticular collection of software is called a "brand" (see brands(5)).
Once installed, a zone's brand may not be changed unless the zone is
first uninstalled.
File Systems
Each zone has its own section of the file system hierarchy, rooted at a
directory known as the zone root. Processes inside the zone can access
only files within that part of the hierarchy, that is, files that are
located beneath the zone root. This prevents processes in one zone from
corrupting or examining file system data associated with another zone.
The chroot(1M) utility can be used within a zone, but can only restrict
the process to a root path accessible within the zone.
In order to preserve file system space, sections of the file system can
be mounted into one or more zones using the read-only option of the
lofs(7FS) file system. This allows the same file system data to be
shared in multiple zones, while preserving the security guarantees sup‐
plied by zones.
NFS and autofs mounts established within a zone are local to that zone;
they cannot be accessed from other zones, including the global zone.
The mounts are removed when the zone is halted or rebooted.
Networking
A zone has its own port number space for TCP, UDP, and SCTP applica‐
tions and typically one or more separate IP addresses (but some config‐
urations of Trusted Extensions share IP address(es) between zones).
For the IP layer (IP routing, ARP, IPsec, IP Filter, and so on) a zone
can either share the configuration and state with the global zone (a
shared-IP zone), or have its distinct IP layer configuration and state
(an exclusive-IP zone).
If a zone is to be connected to the same datalink, that is, be on the
same IP subnet or subnets as the global zone, then it is appropriate
for the zone to use the shared IP instance.
If a zone needs to be isolated at the IP layer on the network, for
instance being connected to different VLANs or different LANs than the
global zone and other non-global zones, then for isolation reasons the
zone should have its exclusive IP.
A shared-IP zone is prevented from doing certain things towards the
network (such as changing its IP address or sending spoofed IP or Eth‐
ernet packets), but an exclusive-IP zone has more or less the same
capabilities towards the network as a separate host that is connected
to the same network interface. In particular, the superuser in such a
zone can change its IP address and spoof ARP packets.
The shared-IP zones are assigned one or more network interface names
and IP addresses in zonecfg(1M). The network interface name(s) must
also be configured in the global zone.
The exclusive-IP zones are assigned one or more network interface names
in zonecfg(1M). The network interface names must be exclusively
assigned to that zone, that is, it (or they) can not be assigned to
some other running zone, nor can they be used by the global zone.
The full IP-level functionality in the form of DHCP client, IPsec and
IP Filter, is available in exclusive-IP zones and not in shared-IP
zones.
Host Identifiers
A zone is capable of emulating a 32-bit host identifier, which can be
configured via zonecfg(1M), for the purpose of system consolidation. If
a zone emulates a host identifier, then commands such as hostid(1) and
sysdef(1M) as well as C interfaces such as sysinfo(2) and gethostid(3C)
that are executed within the context of the zone will display or return
the zone's emulated host identifier rather than the host machine's
identifier.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Availability │SUNWcsu │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOhostid(1), zlogin(1), zonename(1), in.rlogind(1M), sshd(1M), sys‐
def(1M), zoneadm(1M), zonecfg(1M), kill(2), priocntl(2), sysinfo(2),
gethostid(3C), getzoneid(3C), ucred_get(3C), proc(4), attributes(5),
brands(5), privileges(5), crgetzoneid(9F)SunOS 5.10 29 Jan 2009 zones(5)
