112 lines
2.8 KiB
Go
112 lines
2.8 KiB
Go
// Copyright 2018 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package kernel
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import (
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"sync"
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"syscall"
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"gvisor.googlesource.com/gvisor/pkg/refs"
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"gvisor.googlesource.com/gvisor/pkg/sentry/socket/unix/transport"
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)
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// +stateify savable
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type abstractEndpoint struct {
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ep transport.BoundEndpoint
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wr *refs.WeakRef
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name string
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ns *AbstractSocketNamespace
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}
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// WeakRefGone implements refs.WeakRefUser.WeakRefGone.
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func (e *abstractEndpoint) WeakRefGone() {
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e.ns.mu.Lock()
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if e.ns.endpoints[e.name].ep == e.ep {
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delete(e.ns.endpoints, e.name)
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}
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e.ns.mu.Unlock()
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}
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// AbstractSocketNamespace is used to implement the Linux abstract socket functionality.
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//
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// +stateify savable
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type AbstractSocketNamespace struct {
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mu sync.Mutex `state:"nosave"`
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// Keeps mapping from name to endpoint.
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endpoints map[string]abstractEndpoint
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}
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// NewAbstractSocketNamespace returns a new AbstractSocketNamespace.
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func NewAbstractSocketNamespace() *AbstractSocketNamespace {
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return &AbstractSocketNamespace{
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endpoints: make(map[string]abstractEndpoint),
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}
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}
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// A boundEndpoint wraps a transport.BoundEndpoint to maintain a reference on
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// its backing object.
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type boundEndpoint struct {
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transport.BoundEndpoint
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rc refs.RefCounter
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}
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// Release implements transport.BoundEndpoint.Release.
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func (e *boundEndpoint) Release() {
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e.rc.DecRef()
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e.BoundEndpoint.Release()
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}
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// BoundEndpoint retrieves the endpoint bound to the given name. The return
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// value is nil if no endpoint was bound.
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func (a *AbstractSocketNamespace) BoundEndpoint(name string) transport.BoundEndpoint {
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a.mu.Lock()
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defer a.mu.Unlock()
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ep, ok := a.endpoints[name]
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if !ok {
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return nil
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}
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rc := ep.wr.Get()
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if rc == nil {
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delete(a.endpoints, name)
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return nil
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}
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return &boundEndpoint{ep.ep, rc}
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}
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// Bind binds the given socket.
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//
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// When the last reference managed by rc is dropped, ep may be removed from the
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// namespace.
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func (a *AbstractSocketNamespace) Bind(name string, ep transport.BoundEndpoint, rc refs.RefCounter) error {
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a.mu.Lock()
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defer a.mu.Unlock()
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if ep, ok := a.endpoints[name]; ok {
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if rc := ep.wr.Get(); rc != nil {
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rc.DecRef()
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return syscall.EADDRINUSE
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}
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}
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ae := abstractEndpoint{ep: ep, name: name, ns: a}
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ae.wr = refs.NewWeakRef(rc, &ae)
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a.endpoints[name] = ae
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return nil
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}
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