3 files changed, 89 insertions, 0 deletions
diff --git a/pkg/sentry/fs/anon/BUILD b/pkg/sentry/fs/anon/BUILD
new file mode 100644
index 000000000..6b18aee47
--- /dev/null
+++ b/pkg/sentry/fs/anon/BUILD
@@ -0,0 +1,21 @@
+package(licenses = ["notice"])  # Apache 2.0
+
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
+
+go_library(
+    name = "anon",
+    srcs = [
+        "anon.go",
+        "device.go",
+    ],
+    importpath = "gvisor.googlesource.com/gvisor/pkg/sentry/fs/anon",
+    visibility = ["//pkg/sentry:internal"],
+    deps = [
+        "//pkg/abi/linux",
+        "//pkg/sentry/context",
+        "//pkg/sentry/device",
+        "//pkg/sentry/fs",
+        "//pkg/sentry/fs/fsutil",
+        "//pkg/sentry/usermem",
+    ],
+)
diff --git a/pkg/sentry/fs/anon/anon.go b/pkg/sentry/fs/anon/anon.go
new file mode 100644
index 000000000..ddc2c0985
--- /dev/null
+++ b/pkg/sentry/fs/anon/anon.go
@@ -0,0 +1,46 @@
+// Copyright 2018 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package anon implements an anonymous inode, useful for implementing
+// inodes for pseudo filesystems.
+package anon
+
+import (
+	"gvisor.googlesource.com/gvisor/pkg/abi/linux"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/context"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs/fsutil"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
+)
+
+// NewInode constructs an anonymous Inode that is not associated
+// with any real filesystem. Some types depend on completely pseudo
+// "anon" inodes (eventfds, epollfds, etc).
+func NewInode(ctx context.Context) *fs.Inode {
+	return fs.NewInode(fsutil.NewSimpleInodeOperations(fsutil.InodeSimpleAttributes{
+		FSType: linux.ANON_INODE_FS_MAGIC,
+		UAttr: fs.WithCurrentTime(ctx, fs.UnstableAttr{
+			Owner: fs.FileOwnerFromContext(ctx),
+			Perms: fs.FilePermissions{
+				User: fs.PermMask{Read: true, Write: true},
+			},
+			Links: 1,
+		}),
+	}), fs.NewNonCachingMountSource(nil, fs.MountSourceFlags{}), fs.StableAttr{
+		Type:      fs.Anonymous,
+		DeviceID:  PseudoDevice.DeviceID(),
+		InodeID:   PseudoDevice.NextIno(),
+		BlockSize: usermem.PageSize,
+	})
+}
diff --git a/pkg/sentry/fs/anon/device.go b/pkg/sentry/fs/anon/device.go
new file mode 100644
index 000000000..1c666729c
--- /dev/null
+++ b/pkg/sentry/fs/anon/device.go
@@ -0,0 +1,22 @@
+// Copyright 2018 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package anon
+
+import (
+	"gvisor.googlesource.com/gvisor/pkg/sentry/device"
+)
+
+// PseudoDevice is the device on which all anonymous inodes reside.
+var PseudoDevice = device.NewAnonDevice()