diff options
| -rw-r--r-- | pkg/sentry/sighandling/sighandling.go | 75 | ||||
| -rw-r--r-- | pkg/sentry/sighandling/sighandling_unsafe.go | 26 | ||||
| -rw-r--r-- | pkg/syncutil/BUILD | 2 | ||||
| -rw-r--r-- | pkg/syncutil/downgradable_rwmutex_1_12_unsafe.go | 21 | ||||
| -rw-r--r-- | pkg/syncutil/downgradable_rwmutex_1_13_unsafe.go | 16 | ||||
| -rw-r--r-- | pkg/syncutil/downgradable_rwmutex_unsafe.go | 5 | ||||
| -rw-r--r-- | runsc/boot/loader.go | 50 |
7 files changed, 41 insertions, 154 deletions
diff --git a/pkg/sentry/sighandling/sighandling.go b/pkg/sentry/sighandling/sighandling.go index 2f65db70b..ba1f9043d 100644 --- a/pkg/sentry/sighandling/sighandling.go +++ b/pkg/sentry/sighandling/sighandling.go @@ -16,7 +16,6 @@ package sighandling import ( - "fmt" "os" "os/signal" "reflect" @@ -31,37 +30,25 @@ const numSignals = 32 // handleSignals listens for incoming signals and calls the given handler // function. // -// It starts when the start channel is closed, stops when the stop channel -// is closed, and closes done once it will no longer deliver signals to k. -func handleSignals(sigchans []chan os.Signal, handler func(linux.Signal), start, stop, done chan struct{}) { +// It stops when the stop channel is closed. The done channel is closed once it +// will no longer deliver signals to k. +func handleSignals(sigchans []chan os.Signal, handler func(linux.Signal), stop, done chan struct{}) { // Build a select case. - sc := []reflect.SelectCase{{Dir: reflect.SelectRecv, Chan: reflect.ValueOf(start)}} + sc := []reflect.SelectCase{{Dir: reflect.SelectRecv, Chan: reflect.ValueOf(stop)}} for _, sigchan := range sigchans { sc = append(sc, reflect.SelectCase{Dir: reflect.SelectRecv, Chan: reflect.ValueOf(sigchan)}) } - started := false for { // Wait for a notification. index, _, ok := reflect.Select(sc) - // Was it the start / stop channel? + // Was it the stop channel? if index == 0 { if !ok { - if !started { - // start channel; start forwarding and - // swap this case for the stop channel - // to select stop requests. - started = true - sc[0] = reflect.SelectCase{Dir: reflect.SelectRecv, Chan: reflect.ValueOf(stop)} - } else { - // stop channel; stop forwarding and - // clear this case so it is never - // selected again. - started = false - close(done) - sc[0].Chan = reflect.Value{} - } + // Stop forwarding and notify that it's done. + close(done) + return } continue } @@ -73,44 +60,17 @@ func handleSignals(sigchans []chan os.Signal, handler func(linux.Signal), start, // Otherwise, it was a signal on channel N. Index 0 represents the stop // channel, so index N represents the channel for signal N. - signal := linux.Signal(index) - - if !started { - // Kernel cannot receive signals, either because it is - // not ready yet or is shutting down. - // - // Kill ourselves if this signal would have killed the - // process before PrepareForwarding was called. i.e., all - // _SigKill signals; see Go - // src/runtime/sigtab_linux_generic.go. - // - // Otherwise ignore the signal. - // - // TODO(b/114489875): Drop in Go 1.12, which uses tgkill - // in runtime.raise. - switch signal { - case linux.SIGHUP, linux.SIGINT, linux.SIGTERM: - dieFromSignal(signal) - panic(fmt.Sprintf("Failed to die from signal %d", signal)) - default: - continue - } - } - - // Pass the signal to the handler. - handler(signal) + handler(linux.Signal(index)) } } -// PrepareHandler ensures that synchronous signals are passed to the given -// handler function and returns a callback that starts signal delivery, which -// itself returns a callback that stops signal handling. +// StartSignalForwarding ensures that synchronous signals are passed to the +// given handler function and returns a callback that stops signal delivery. // // Note that this function permanently takes over signal handling. After the // stop callback, signals revert to the default Go runtime behavior, which // cannot be overridden with external calls to signal.Notify. -func PrepareHandler(handler func(linux.Signal)) func() func() { - start := make(chan struct{}) +func StartSignalForwarding(handler func(linux.Signal)) func() { stop := make(chan struct{}) done := make(chan struct{}) @@ -128,13 +88,10 @@ func PrepareHandler(handler func(linux.Signal)) func() func() { signal.Notify(sigchan, syscall.Signal(sig)) } // Start up our listener. - go handleSignals(sigchans, handler, start, stop, done) // S/R-SAFE: synchronized by Kernel.extMu. + go handleSignals(sigchans, handler, stop, done) // S/R-SAFE: synchronized by Kernel.extMu. - return func() func() { - close(start) - return func() { - close(stop) - <-done - } + return func() { + close(stop) + <-done } } diff --git a/pkg/sentry/sighandling/sighandling_unsafe.go b/pkg/sentry/sighandling/sighandling_unsafe.go index c303435d5..1ebe22d34 100644 --- a/pkg/sentry/sighandling/sighandling_unsafe.go +++ b/pkg/sentry/sighandling/sighandling_unsafe.go @@ -15,8 +15,6 @@ package sighandling import ( - "fmt" - "runtime" "syscall" "unsafe" @@ -48,27 +46,3 @@ func IgnoreChildStop() error { return nil } - -// dieFromSignal kills the current process with sig. -// -// Preconditions: The default action of sig is termination. -func dieFromSignal(sig linux.Signal) { - runtime.LockOSThread() - defer runtime.UnlockOSThread() - - sa := sigaction{handler: linux.SIG_DFL} - if _, _, e := syscall.RawSyscall6(syscall.SYS_RT_SIGACTION, uintptr(sig), uintptr(unsafe.Pointer(&sa)), 0, linux.SignalSetSize, 0, 0); e != 0 { - panic(fmt.Sprintf("rt_sigaction failed: %v", e)) - } - - set := linux.MakeSignalSet(sig) - if _, _, e := syscall.RawSyscall6(syscall.SYS_RT_SIGPROCMASK, linux.SIG_UNBLOCK, uintptr(unsafe.Pointer(&set)), 0, linux.SignalSetSize, 0, 0); e != 0 { - panic(fmt.Sprintf("rt_sigprocmask failed: %v", e)) - } - - if err := syscall.Tgkill(syscall.Getpid(), syscall.Gettid(), syscall.Signal(sig)); err != nil { - panic(fmt.Sprintf("tgkill failed: %v", err)) - } - - panic("failed to die") -} diff --git a/pkg/syncutil/BUILD b/pkg/syncutil/BUILD index b06a90bef..cb1f41628 100644 --- a/pkg/syncutil/BUILD +++ b/pkg/syncutil/BUILD @@ -31,8 +31,6 @@ go_template( go_library( name = "syncutil", srcs = [ - "downgradable_rwmutex_1_12_unsafe.go", - "downgradable_rwmutex_1_13_unsafe.go", "downgradable_rwmutex_unsafe.go", "memmove_unsafe.go", "norace_unsafe.go", diff --git a/pkg/syncutil/downgradable_rwmutex_1_12_unsafe.go b/pkg/syncutil/downgradable_rwmutex_1_12_unsafe.go deleted file mode 100644 index 7c6336e62..000000000 --- a/pkg/syncutil/downgradable_rwmutex_1_12_unsafe.go +++ /dev/null @@ -1,21 +0,0 @@ -// Copyright 2009 The Go Authors. All rights reserved. -// Copyright 2019 The gVisor Authors. -// Use of this source code is governed by a BSD-style -// license that can be found in the LICENSE file. - -// +build go1.12 -// +build !go1.13 - -// TODO(b/133868570): Delete once Go 1.12 is no longer supported. - -package syncutil - -import _ "unsafe" - -//go:linkname runtimeSemrelease112 sync.runtime_Semrelease -func runtimeSemrelease112(s *uint32, handoff bool) - -func runtimeSemrelease(s *uint32, handoff bool, skipframes int) { - // 'skipframes' is only available starting from 1.13. - runtimeSemrelease112(s, handoff) -} diff --git a/pkg/syncutil/downgradable_rwmutex_1_13_unsafe.go b/pkg/syncutil/downgradable_rwmutex_1_13_unsafe.go deleted file mode 100644 index 3c3673119..000000000 --- a/pkg/syncutil/downgradable_rwmutex_1_13_unsafe.go +++ /dev/null @@ -1,16 +0,0 @@ -// Copyright 2009 The Go Authors. All rights reserved. -// Copyright 2019 The gVisor Authors. -// Use of this source code is governed by a BSD-style -// license that can be found in the LICENSE file. - -// +build go1.13 -// +build !go1.15 - -// Check go:linkname function signatures when updating Go version. - -package syncutil - -import _ "unsafe" - -//go:linkname runtimeSemrelease sync.runtime_Semrelease -func runtimeSemrelease(s *uint32, handoff bool, skipframes int) diff --git a/pkg/syncutil/downgradable_rwmutex_unsafe.go b/pkg/syncutil/downgradable_rwmutex_unsafe.go index 07feca402..51e11555d 100644 --- a/pkg/syncutil/downgradable_rwmutex_unsafe.go +++ b/pkg/syncutil/downgradable_rwmutex_unsafe.go @@ -3,7 +3,7 @@ // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. -// +build go1.12 +// +build go1.13 // +build !go1.15 // Check go:linkname function signatures when updating Go version. @@ -27,6 +27,9 @@ import ( //go:linkname runtimeSemacquire sync.runtime_Semacquire func runtimeSemacquire(s *uint32) +//go:linkname runtimeSemrelease sync.runtime_Semrelease +func runtimeSemrelease(s *uint32, handoff bool, skipframes int) + // DowngradableRWMutex is identical to sync.RWMutex, but adds the DowngradeLock // method. type DowngradableRWMutex struct { diff --git a/runsc/boot/loader.go b/runsc/boot/loader.go index df6052c88..bc1d0c1bb 100644 --- a/runsc/boot/loader.go +++ b/runsc/boot/loader.go @@ -93,10 +93,6 @@ type Loader struct { // spec is the base configuration for the root container. spec *specs.Spec - // startSignalForwarding enables forwarding of signals to the sandboxed - // container. It should be called after the init process is loaded. - startSignalForwarding func() func() - // stopSignalForwarding disables forwarding of signals to the sandboxed // container. It should be called when a sandbox is destroyed. stopSignalForwarding func() @@ -336,29 +332,6 @@ func New(args Args) (*Loader, error) { return nil, fmt.Errorf("ignore child stop signals failed: %v", err) } - // Handle signals by forwarding them to the root container process - // (except for panic signal, which should cause a panic). - l.startSignalForwarding = sighandling.PrepareHandler(func(sig linux.Signal) { - // Panic signal should cause a panic. - if args.Conf.PanicSignal != -1 && sig == linux.Signal(args.Conf.PanicSignal) { - panic("Signal-induced panic") - } - - // Otherwise forward to root container. - deliveryMode := DeliverToProcess - if args.Console { - // Since we are running with a console, we should - // forward the signal to the foreground process group - // so that job control signals like ^C can be handled - // properly. - deliveryMode = DeliverToForegroundProcessGroup - } - log.Infof("Received external signal %d, mode: %v", sig, deliveryMode) - if err := l.signal(args.ID, 0, int32(sig), deliveryMode); err != nil { - log.Warningf("error sending signal %v to container %q: %v", sig, args.ID, err) - } - }) - // Create the control server using the provided FD. // // This must be done *after* we have initialized the kernel since the @@ -566,8 +539,27 @@ func (l *Loader) run() error { ep.tty.InitForegroundProcessGroup(ep.tg.ProcessGroup()) } - // Start signal forwarding only after an init process is created. - l.stopSignalForwarding = l.startSignalForwarding() + // Handle signals by forwarding them to the root container process + // (except for panic signal, which should cause a panic). + l.stopSignalForwarding = sighandling.StartSignalForwarding(func(sig linux.Signal) { + // Panic signal should cause a panic. + if l.conf.PanicSignal != -1 && sig == linux.Signal(l.conf.PanicSignal) { + panic("Signal-induced panic") + } + + // Otherwise forward to root container. + deliveryMode := DeliverToProcess + if l.console { + // Since we are running with a console, we should forward the signal to + // the foreground process group so that job control signals like ^C can + // be handled properly. + deliveryMode = DeliverToForegroundProcessGroup + } + log.Infof("Received external signal %d, mode: %v", sig, deliveryMode) + if err := l.signal(l.sandboxID, 0, int32(sig), deliveryMode); err != nil { + log.Warningf("error sending signal %v to container %q: %v", sig, l.sandboxID, err) + } + }) log.Infof("Process should have started...") l.watchdog.Start() |