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// Copyright 2020 The gVisor Authors.
//
// 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 kernel
import (
"time"
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/context"
"gvisor.dev/gvisor/pkg/cpuid"
"gvisor.dev/gvisor/pkg/sentry/inet"
"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
"gvisor.dev/gvisor/pkg/sentry/kernel/ipc"
ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time"
"gvisor.dev/gvisor/pkg/sentry/limits"
"gvisor.dev/gvisor/pkg/sentry/pgalloc"
"gvisor.dev/gvisor/pkg/sentry/platform"
"gvisor.dev/gvisor/pkg/sentry/unimpl"
"gvisor.dev/gvisor/pkg/sentry/uniqueid"
"gvisor.dev/gvisor/pkg/sentry/vfs"
"gvisor.dev/gvisor/pkg/sync"
)
// Deadline implements context.Context.Deadline.
func (*Task) Deadline() (time.Time, bool) {
return time.Time{}, false
}
// Done implements context.Context.Done.
func (*Task) Done() <-chan struct{} {
return nil
}
// Err implements context.Context.Err.
func (*Task) Err() error {
return nil
}
// Value implements context.Context.Value.
//
// Preconditions: The caller must be running on the task goroutine.
func (t *Task) Value(key any) any {
// This function is very hot; skip this check outside of +race builds.
if sync.RaceEnabled {
t.assertTaskGoroutine()
}
return t.contextValue(key, true /* isTaskGoroutine */)
}
func (t *Task) contextValue(key any, isTaskGoroutine bool) any {
switch key {
case CtxCanTrace:
return t.CanTrace
case CtxKernel:
return t.k
case CtxPIDNamespace:
return t.tg.pidns
case CtxUTSNamespace:
if !isTaskGoroutine {
t.mu.Lock()
defer t.mu.Unlock()
}
return t.utsns
case ipc.CtxIPCNamespace:
if !isTaskGoroutine {
t.mu.Lock()
defer t.mu.Unlock()
}
ipcns := t.ipcns
ipcns.IncRef()
return ipcns
case CtxTask:
return t
case auth.CtxCredentials:
return t.creds.Load()
case auth.CtxThreadGroupID:
return int32(t.tg.ID())
case vfs.CtxRoot:
if !isTaskGoroutine {
t.mu.Lock()
defer t.mu.Unlock()
}
return t.fsContext.RootDirectory()
case vfs.CtxMountNamespace:
if !isTaskGoroutine {
t.mu.Lock()
defer t.mu.Unlock()
}
t.mountNamespace.IncRef()
return t.mountNamespace
case inet.CtxStack:
return t.NetworkContext()
case ktime.CtxRealtimeClock:
return t.k.RealtimeClock()
case limits.CtxLimits:
return t.tg.limits
case linux.CtxSignalNoInfoFunc:
return func(sig linux.Signal) error {
return t.SendSignal(SignalInfoNoInfo(sig, t, t))
}
case pgalloc.CtxMemoryFile:
return t.k.mf
case pgalloc.CtxMemoryFileProvider:
return t.k
case platform.CtxPlatform:
return t.k
case uniqueid.CtxGlobalUniqueID:
return t.k.UniqueID()
case uniqueid.CtxGlobalUniqueIDProvider:
return t.k
case uniqueid.CtxInotifyCookie:
return t.k.GenerateInotifyCookie()
case unimpl.CtxEvents:
return t.k
case cpuid.CtxFeatureSet:
return t.k.featureSet
default:
return nil
}
}
// fallbackContext adds a level of indirection for embedding to resolve
// ambiguity for method resolution. We favor context.NoTask.
type fallbackTask struct {
*Task
}
// taskAsyncContext implements context.Context for a goroutine that performs
// work on behalf of a Task, but is not the task goroutine.
type taskAsyncContext struct {
context.NoTask
fallbackTask
}
// Value implements context.Context.Value.
func (t *taskAsyncContext) Value(key any) any {
return t.fallbackTask.contextValue(key, false /* isTaskGoroutine */)
}
// AsyncContext returns a context.Context representing t. The returned
// context.Context is intended for use by goroutines other than t's task
// goroutine; for example, signal delivery to t will not interrupt goroutines
// that are blocking using the returned context.Context.
func (t *Task) AsyncContext() context.Context {
return &taskAsyncContext{
fallbackTask: fallbackTask{t},
}
}
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