Add features.md to formalize the runc features JSON

Add `features.md` and `features-linux.md`, to formalize the `runc features` JSON that was introduced in runc v1.1. A runtime caller MAY use this JSON to detect the features implemented by the runtime. The spec corresponds to https://github.com/opencontainers/runc/blob/1b747a43f0f57e31619f0dc9289a73beaf52ee0e/types/features/features.go (opencontainers/runc PR 3296, opencontainers/runc PR 3310) Signed-off-by: Akihiro Suda <[email protected]>
opencontainers · Dec 9, 2021 · 0b75bf9 · 0b75bf9
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diff --git a/Makefile b/Makefile
@@ -30,6 +30,8 @@ DOC_FILES := \
 	config.md \
 	config-linux.md \
 	config-solaris.md \
+	features.md \
+	features-linux.md \
 	glossary.md
 
 default: docs

diff --git a/features-linux.md b/features-linux.md
@@ -0,0 +1,183 @@
+# <a name="linuxFeatures" />Linux Features Document
+
+This document describes the [Linux-specific section](features.md#platform-specific-features) of the [features document](features.md).
+
+## <a name="linuxFeaturesNamespaces" />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`](config-linux.md#namespaces).
+
+### Example
+
+```json
+"namespaces": [
+  "cgroup",
+  "ipc",
+  "mount",
+  "network",
+  "pid",
+  "user",
+  "uts"
+]
+```
+
+## <a name="linuxFeaturesCapabilities" />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`](config.md#linux-process).
+
+### Example
+
+```json
+"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"
+]
+```
+
+## <a name="linuxFeaturesCgroup" />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.
+
+### Example
+
+```json
+"cgroup": {
+  "v1": true,
+  "v2": true,
+  "systemd": true,
+  "systemdUser": true
+}
+```
+
+## <a name="linuxFeaturesSeccomp" />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`](config-linux.md#seccomp).
+* **`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`](config-linux.md#seccomp).
+* **`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`](config-linux.md#seccomp).
+
+### Example
+
+```json
+"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"
+  ]
+}
+```
+
+## <a name="linuxFeaturesApparmor" />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
+
+```json
+"apparmor": {
+  "enabled": true
+}
+```
+
+## <a name="linuxFeaturesApparmor" />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 AppArmor.
+
+### Example
+
+```json
+"selinux": {
+  "enabled": true
+}
+```