75 lines
2.3 KiB
Go
75 lines
2.3 KiB
Go
// Copyright 2018 Google Inc.
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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 sighandling
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import (
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"fmt"
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"runtime"
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"syscall"
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"unsafe"
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"gvisor.googlesource.com/gvisor/pkg/abi/linux"
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)
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// TODO: Move to pkg/abi/linux along with definitions in
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// pkg/sentry/arch.
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type sigaction struct {
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handler uintptr
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flags uint64
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restorer uintptr
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mask uint64
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}
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// IgnoreChildStop sets the SA_NOCLDSTOP flag, causing child processes to not
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// generate SIGCHLD when they stop.
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func IgnoreChildStop() error {
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var sa sigaction
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// Get the existing signal handler information, and set the flag.
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if _, _, e := syscall.RawSyscall6(syscall.SYS_RT_SIGACTION, uintptr(syscall.SIGCHLD), 0, uintptr(unsafe.Pointer(&sa)), linux.SignalSetSize, 0, 0); e != 0 {
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return e
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}
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sa.flags |= linux.SA_NOCLDSTOP
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if _, _, e := syscall.RawSyscall6(syscall.SYS_RT_SIGACTION, uintptr(syscall.SIGCHLD), uintptr(unsafe.Pointer(&sa)), 0, linux.SignalSetSize, 0, 0); e != 0 {
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return e
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}
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return nil
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}
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// dieFromSignal kills the current process with sig.
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//
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// Preconditions: The default action of sig is termination.
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func dieFromSignal(sig linux.Signal) {
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runtime.LockOSThread()
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defer runtime.UnlockOSThread()
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sa := sigaction{handler: linux.SIG_DFL}
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if _, _, e := syscall.RawSyscall6(syscall.SYS_RT_SIGACTION, uintptr(sig), uintptr(unsafe.Pointer(&sa)), 0, linux.SignalSetSize, 0, 0); e != 0 {
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panic(fmt.Sprintf("rt_sigaction failed: %v", e))
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}
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set := linux.MakeSignalSet(sig)
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if _, _, e := syscall.RawSyscall6(syscall.SYS_RT_SIGPROCMASK, linux.SIG_UNBLOCK, uintptr(unsafe.Pointer(&set)), 0, linux.SignalSetSize, 0, 0); e != 0 {
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panic(fmt.Sprintf("rt_sigprocmask failed: %v", e))
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}
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if err := syscall.Tgkill(syscall.Getpid(), syscall.Gettid(), syscall.Signal(sig)); err != nil {
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panic(fmt.Sprintf("tgkill failed: %v", err))
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}
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panic("failed to die")
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}
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