90 lines
2.5 KiB
Go
90 lines
2.5 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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"gvisor.googlesource.com/gvisor/pkg/abi/linux"
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"gvisor.googlesource.com/gvisor/pkg/sentry/arch"
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)
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// SignalHandlers holds information about signal actions.
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//
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// +stateify savable
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type SignalHandlers struct {
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// mu protects actions, as well as the signal state of all tasks and thread
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// groups using this SignalHandlers object. (See comment on
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// ThreadGroup.signalHandlers.)
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mu sync.Mutex `state:"nosave"`
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// actions is the action to be taken upon receiving each signal.
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actions map[linux.Signal]arch.SignalAct
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}
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// NewSignalHandlers returns a new SignalHandlers specifying all default
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// actions.
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func NewSignalHandlers() *SignalHandlers {
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return &SignalHandlers{
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actions: make(map[linux.Signal]arch.SignalAct),
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}
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}
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// Fork returns a copy of sh for a new thread group.
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func (sh *SignalHandlers) Fork() *SignalHandlers {
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sh2 := NewSignalHandlers()
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sh.mu.Lock()
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defer sh.mu.Unlock()
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for sig, act := range sh.actions {
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sh2.actions[sig] = act
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}
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return sh2
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}
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// CopyForExec returns a copy of sh for a thread group that is undergoing an
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// execve. (See comments in Task.finishExec.)
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func (sh *SignalHandlers) CopyForExec() *SignalHandlers {
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sh2 := NewSignalHandlers()
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sh.mu.Lock()
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defer sh.mu.Unlock()
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for sig, act := range sh.actions {
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if act.Handler == arch.SignalActIgnore {
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sh2.actions[sig] = arch.SignalAct{
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Handler: arch.SignalActIgnore,
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}
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}
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}
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return sh2
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}
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// IsIgnored returns true if the signal is ignored.
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func (sh *SignalHandlers) IsIgnored(sig linux.Signal) bool {
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sh.mu.Lock()
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defer sh.mu.Unlock()
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sa, ok := sh.actions[sig]
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return ok && sa.Handler == arch.SignalActIgnore
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}
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// dequeueActionLocked returns the SignalAct that should be used to handle sig.
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//
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// Preconditions: sh.mu must be locked.
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func (sh *SignalHandlers) dequeueAction(sig linux.Signal) arch.SignalAct {
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act := sh.actions[sig]
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if act.IsResetHandler() {
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delete(sh.actions, sig)
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}
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return act
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}
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