Add FreeBSD Platform Support

[nayuta723]

Overview

Add FreeBSD Platform Support

Implement the FreeBSD-specific specification:

• Add FreeBSD struct including devices and jail configuration
• Implement FreeBSDJail, FreeBSDJailAllow, and related types

Runtime Spec Reference

Implemented in runtime-spec as follows:

Found in https://github.com/opencontainers/runtime-spec/blob/main/specs-go/config.go:

FreeBSDJailAllow

// FreeBSDJailAllow describes jail capabilities
type FreeBSDJailAllow struct {
	SetHostname   bool     `json:"setHostname,omitempty"`
	RawSockets    bool     `json:"rawSockets,omitempty"`
	Chflags       bool     `json:"chflags,omitempty"`
	Mount         []string `json:"mount,omitempty"`
	Quotas        bool     `json:"quotas,omitempty"`
	SocketAf      bool     `json:"socketAf,omitempty"`
	Mlock         bool     `json:"mlock,omitempty"`
	ReservedPorts bool     `json:"reservedPorts,omitempty"`
	Suser         bool     `json:"suser,omitempty"`
}

FreeBSDJail

// FreeBSDJail describes how to configure the container's jail
type FreeBSDJail struct {
	// Parent jail name - this can be used to share a single vnet
	// across several containers
	Parent string `json:"parent,omitempty"`
	// Whether to use parent UTS names or override in the container
	Host FreeBSDSharing `json:"host,omitempty"`
	// IPv4 address sharing for the container
	Ip4 FreeBSDSharing `json:"ip4,omitempty"`
	// IPv4 addresses for the container
	Ip4Addr []string `json:"ip4Addr,omitempty"`
	// IPv6 address sharing for the container
	Ip6 FreeBSDSharing `json:"ip6,omitempty"`
	// IPv6 addresses for the container
	Ip6Addr []string `json:"ip6Addr,omitempty"`
	// Which network stack to use for the container
	Vnet FreeBSDSharing `json:"vnet,omitempty"`
	// If set, Ip4Addr and Ip6Addr addresses will be added to this interface
	Interface string `json:"interface,omitempty"`
	// List interfaces to be moved to the container's vnet
	VnetInterfaces []string `json:"vnetInterfaces,omitempty"`
	// SystemV IPC message sharing for the container
	SysVMsg FreeBSDSharing `json:"sysvmsg,omitempty"`
	// SystemV semaphore message sharing for the container
	SysVSem FreeBSDSharing `json:"sysvsem,omitempty"`
	// SystemV memory sharing for the container
	SysVShm FreeBSDSharing `json:"sysvshm,omitempty"`
	// Mount visibility (see jail(8) for details)
	EnforceStatfs *int `json:"enforceStatfs,omitempty"`
	// Jail capabilities
	Allow *FreeBSDJailAllow `json:"allow,omitempty"`
}

FreeBSD

// FreeBSD contains platform-specific configuration for FreeBSD based containers.
type FreeBSD struct {
	// Devices which are accessible in the container
	Devices []FreeBSDDevice `json:"devices,omitempty"`
	// Jail definition for this container
	Jail *FreeBSDJail `json:"jail,omitempty"`
}

Related to #309