runtime-spec/features-linux.md

Linux Features Structure

This document describes the Linux-specific section of the Features structure.

Namespaces

• namespaces (array of strings, OPTIONAL) The recognized names of the namespaces, including namespaces that might not be supported by the host operating system. The runtime MUST recognize the elements in this array as the type of linux.namespaces objects in config.json.

Example

"namespaces": [
  "cgroup",
  "ipc",
  "mount",
  "network",
  "pid",
  "user",
  "uts"
]

Capabilities

• capabilities (array of strings, OPTIONAL) The recognized names of the capabilities, including capabilities that might not be supported by the host operating system. The runtime MUST recognize the elements in this array in the process.capabilities object of config.json.

Example

"capabilities": [
  "CAP_CHOWN",
  "CAP_DAC_OVERRIDE",
  "CAP_DAC_READ_SEARCH",
  "CAP_FOWNER",
  "CAP_FSETID",
  "CAP_KILL",
  "CAP_SETGID",
  "CAP_SETUID",
  "CAP_SETPCAP",
  "CAP_LINUX_IMMUTABLE",
  "CAP_NET_BIND_SERVICE",
  "CAP_NET_BROADCAST",
  "CAP_NET_ADMIN",
  "CAP_NET_RAW",
  "CAP_IPC_LOCK",
  "CAP_IPC_OWNER",
  "CAP_SYS_MODULE",
  "CAP_SYS_RAWIO",
  "CAP_SYS_CHROOT",
  "CAP_SYS_PTRACE",
  "CAP_SYS_PACCT",
  "CAP_SYS_ADMIN",
  "CAP_SYS_BOOT",
  "CAP_SYS_NICE",
  "CAP_SYS_RESOURCE",
  "CAP_SYS_TIME",
  "CAP_SYS_TTY_CONFIG",
  "CAP_MKNOD",
  "CAP_LEASE",
  "CAP_AUDIT_WRITE",
  "CAP_AUDIT_CONTROL",
  "CAP_SETFCAP",
  "CAP_MAC_OVERRIDE",
  "CAP_MAC_ADMIN",
  "CAP_SYSLOG",
  "CAP_WAKE_ALARM",
  "CAP_BLOCK_SUSPEND",
  "CAP_AUDIT_READ",
  "CAP_PERFMON",
  "CAP_BPF",
  "CAP_CHECKPOINT_RESTORE"
]

Cgroup

cgroup (object, OPTIONAL) represents the runtime's implementation status of cgroup managers. Irrelevant to the cgroup version of the host operating system.

• v1 (bool, OPTIONAL) represents whether the runtime supports cgroup v1.
• v2 (bool, OPTIONAL) represents whether the runtime supports cgroup v2.
• systemd (bool, OPTIONAL) represents whether the runtime supports system-wide systemd cgroup manager.
• systemdUser (bool, OPTIONAL) represents whether the runtime supports user-scoped systemd cgroup manager.
• rdma (bool, OPTIONAL) represents whether the runtime supports RDMA cgroup controller.

Example

"cgroup": {
  "v1": true,
  "v2": true,
  "systemd": true,
  "systemdUser": true,
  "rdma": false
}

Seccomp

seccomp (object, OPTIONAL) represents the runtime's implementation status of seccomp. Irrelevant to the kernel version of the host operating system.

• enabled (bool, OPTIONAL) represents whether the runtime supports seccomp.
• actions (array of strings, OPTIONAL) The recognized names of the seccomp actions. The runtime MUST recognize the elements in this array in the syscalls[].action property of the linux.seccomp object in config.json.
• operators (array of strings, OPTIONAL) The recognized names of the seccomp operators. The runtime MUST recognize the elements in this array in the syscalls[].args[].op property of the linux.seccomp object in config.json.
• archs (array of strings, OPTIONAL) The recognized names of the seccomp architectures. The runtime MUST recognize the elements in this array in the architectures property of the linux.seccomp object in config.json.
• knownFlags (array of strings, OPTIONAL) The recognized names of the seccomp flags. The runtime MUST recognize the elements in this array in the flags property of the linux.seccomp object in config.json.
• supportedFlags (array of strings, OPTIONAL) The recognized and supported names of the seccomp flags. This list may be a subset of knownFlags due to some flags not supported by the current kernel and/or libseccomp. The runtime MUST recognize and support the elements in this array in the flags property of the linux.seccomp object in config.json.

Example

"seccomp": {
  "enabled": true,
  "actions": [
    "SCMP_ACT_ALLOW",
    "SCMP_ACT_ERRNO",
    "SCMP_ACT_KILL",
    "SCMP_ACT_LOG",
    "SCMP_ACT_NOTIFY",
    "SCMP_ACT_TRACE",
    "SCMP_ACT_TRAP"
  ],
  "operators": [
    "SCMP_CMP_EQ",
    "SCMP_CMP_GE",
    "SCMP_CMP_GT",
    "SCMP_CMP_LE",
    "SCMP_CMP_LT",
    "SCMP_CMP_MASKED_EQ",
    "SCMP_CMP_NE"
  ],
  "archs": [
    "SCMP_ARCH_AARCH64",
    "SCMP_ARCH_ARM",
    "SCMP_ARCH_MIPS",
    "SCMP_ARCH_MIPS64",
    "SCMP_ARCH_MIPS64N32",
    "SCMP_ARCH_MIPSEL",
    "SCMP_ARCH_MIPSEL64",
    "SCMP_ARCH_MIPSEL64N32",
    "SCMP_ARCH_PPC",
    "SCMP_ARCH_PPC64",
    "SCMP_ARCH_PPC64LE",
    "SCMP_ARCH_S390",
    "SCMP_ARCH_S390X",
    "SCMP_ARCH_X32",
    "SCMP_ARCH_X86",
    "SCMP_ARCH_X86_64"
  ],
  "knownFlags": [
    "SECCOMP_FILTER_FLAG_LOG"
  ],
  "supportedFlags": [
    "SECCOMP_FILTER_FLAG_LOG"
  ]
}

AppArmor

apparmor (object, OPTIONAL) represents the runtime's implementation status of AppArmor. Irrelevant to the availability of AppArmor on the host operating system.

• enabled (bool, OPTIONAL) represents whether the runtime supports AppArmor.

Example

"apparmor": {
  "enabled": true
}

SELinux

selinux (object, OPTIONAL) represents the runtime's implementation status of SELinux. Irrelevant to the availability of SELinux on the host operating system.

• enabled (bool, OPTIONAL) represents whether the runtime supports SELinux.

Example

"selinux": {
  "enabled": true
}

MemoryPolicy

memoryPolicy (object, OPTIONAL) represents the runtime's implementation status of memoryPolicy.

• modes (array of strings, OPTIONAL). Recognized memory policies. Includes policies that may not be supported by the host operating system. The runtime MUST recognize the elements in this array as the mode of linux.memoryPolicy objects in config.json.

• flags (array of strings, OPTIONAL). Recognized flags for memory policies. Includes flags that may not be supported by the host operating system. The runtime MUST recognize the elements in this in the flags property of the linux.memoryPolicy object in config.json

Example

"memoryPolicy": {
  "modes": [
    "MPOL_DEFAULT",
    "MPOL_BIND",
    "MPOL_INTERLEAVE",
    "MPOL_WEIGHTED_INTERLEAVE",
    "MPOL_PREFERRED",
    "MPOL_PREFERRED_MANY",
    "MPOL_LOCAL"
  ],
  "flags": [
    "MPOL_F_NUMA_BALANCING",
    "MPOL_F_RELATIVE_NODES",
    "MPOL_F_STATIC_NODES"
  ]
}

Intel RDT

intelRdt (object, OPTIONAL) represents the runtime's implementation status of Intel RDT. Irrelevant to the availability of Intel RDT on the host operating system.

• enabled (bool, OPTIONAL) represents whether the runtime supports Intel RDT.
• schemata (bool, OPTIONAL) represents whether the (schemata field of linux.intelRdt in config.json)[config-linux.md#intelrdt] is supported.

Example

"intelRdt": {
  "enabled": true,
  "schemata": true
}

MountExtensions

mountExtensions (object, OPTIONAL) represents whether the runtime supports certain mount features, irrespective of the availability of the features on the host operating system.

• idmap (object, OPTIONAL) represents whether the runtime supports idmap mounts using the uidMappings and gidMappings properties of the mount.
  • enabled (bool, OPTIONAL) represents whether the runtime parses and attempts to use the uidMappings and gidMappings properties of mounts if provided. Note that it is possible for runtimes to have partial implementations of id-mapped mounts support (such as only allowing mounts which have mappings matching the container's user namespace, or only allowing the id-mapped bind-mounts). In such cases, runtimes MUST still set this value to true, to indicate that the runtime recognises the uidMappings and gidMappings properties.

Example

"mountExtensions": {
  "idmap":{
    "enabled": true
  }
}

NetDevices

netDevices (object, OPTIONAL) represents the runtime's implementation status of Linux network devices.

• enabled (bool, OPTIONAL) represents whether the runtime supports the capability to move Linux network devices into the container's network namespace.

Example

"netDevices": {
  "enabled": true
}