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// Copyright 2018 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 (
"fmt"
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/log"
"gvisor.dev/gvisor/pkg/sentry/platform"
)
// SignalPanic is used to panic the running threads. It is a signal which
// cannot be used by the application: it must be caught and ignored by the
// runtime (in order to catch possible races).
const SignalPanic = linux.SIGUSR2
// sendExternalSignal is called when an asynchronous signal is sent to the
// sentry ("in sentry context"). On some platforms, it may also be called when
// an asynchronous signal is sent to sandboxed application threads ("in
// application context").
//
// context is used only for debugging to differentiate these cases.
//
// Preconditions: Kernel must have an init process.
func (k *Kernel) sendExternalSignal(info *linux.SignalInfo, context string) {
switch linux.Signal(info.Signo) {
case linux.SIGURG:
// Sent by the Go 1.14+ runtime for asynchronous goroutine preemption.
case platform.SignalInterrupt:
// Assume that a call to platform.Context.Interrupt() misfired.
case SignalPanic:
// SignalPanic is also specially handled in sentry setup to ensure that
// it causes a panic even after tasks exit, but SignalPanic may also
// be sent here if it is received while in app context.
panic("Signal-induced panic")
default:
log.Infof("Received external signal %d in %s context", info.Signo, context)
if k.globalInit == nil {
panic(fmt.Sprintf("Received external signal %d before init created", info.Signo))
}
k.globalInit.SendSignal(info)
}
}
// SignalInfoPriv returns a SignalInfo equivalent to Linux's SEND_SIG_PRIV.
func SignalInfoPriv(sig linux.Signal) *linux.SignalInfo {
return &linux.SignalInfo{
Signo: int32(sig),
Code: linux.SI_KERNEL,
}
}
// SignalInfoNoInfo returns a SignalInfo equivalent to Linux's SEND_SIG_NOINFO.
func SignalInfoNoInfo(sig linux.Signal, sender, receiver *Task) *linux.SignalInfo {
info := &linux.SignalInfo{
Signo: int32(sig),
Code: linux.SI_USER,
}
info.SetPID(int32(receiver.tg.pidns.IDOfThreadGroup(sender.tg)))
info.SetUID(int32(sender.Credentials().RealKUID.In(receiver.UserNamespace()).OrOverflow()))
return info
}
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