diff options
| -rwxr-xr-x | pkg/abi/linux/signalfd.go | 45 | ||||
| -rwxr-xr-x | pkg/sentry/kernel/kernel_state_autogen.go | 1 | ||||
| -rwxr-xr-x | pkg/sentry/kernel/signalfd/signalfd.go | 137 | ||||
| -rwxr-xr-x | pkg/sentry/kernel/signalfd/signalfd_state_autogen.go | 24 | ||||
| -rw-r--r-- | pkg/sentry/kernel/task.go | 8 | ||||
| -rw-r--r-- | pkg/sentry/kernel/task_signals.go | 18 | ||||
| -rw-r--r-- | pkg/sentry/syscalls/linux/linux64.go | 4 | ||||
| -rw-r--r-- | pkg/sentry/syscalls/linux/sys_signal.go | 77 |
8 files changed, 312 insertions, 2 deletions
diff --git a/pkg/abi/linux/signalfd.go b/pkg/abi/linux/signalfd.go new file mode 100755 index 000000000..85fad9956 --- /dev/null +++ b/pkg/abi/linux/signalfd.go @@ -0,0 +1,45 @@ +// Copyright 2019 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 linux + +const ( + // SFD_NONBLOCK is a signalfd(2) flag. + SFD_NONBLOCK = 00004000 + + // SFD_CLOEXEC is a signalfd(2) flag. + SFD_CLOEXEC = 02000000 +) + +// SignalfdSiginfo is the siginfo encoding for signalfds. +type SignalfdSiginfo struct { + Signo uint32 + Errno int32 + Code int32 + PID uint32 + UID uint32 + FD int32 + TID uint32 + Band uint32 + Overrun uint32 + TrapNo uint32 + Status int32 + Int int32 + Ptr uint64 + UTime uint64 + STime uint64 + Addr uint64 + AddrLSB uint16 + _ [48]uint8 +} diff --git a/pkg/sentry/kernel/kernel_state_autogen.go b/pkg/sentry/kernel/kernel_state_autogen.go index bf909f2fc..7f92332a2 100755 --- a/pkg/sentry/kernel/kernel_state_autogen.go +++ b/pkg/sentry/kernel/kernel_state_autogen.go @@ -510,6 +510,7 @@ func (x *syslog) load(m state.Map) { func (x *Task) beforeSave() {} func (x *Task) save(m state.Map) { x.beforeSave() + if !state.IsZeroValue(x.signalQueue) { m.Failf("signalQueue is %v, expected zero", x.signalQueue) } var ptraceTracer *Task = x.savePtraceTracer() m.SaveValue("ptraceTracer", ptraceTracer) var logPrefix string = x.saveLogPrefix() diff --git a/pkg/sentry/kernel/signalfd/signalfd.go b/pkg/sentry/kernel/signalfd/signalfd.go new file mode 100755 index 000000000..06fd5ec88 --- /dev/null +++ b/pkg/sentry/kernel/signalfd/signalfd.go @@ -0,0 +1,137 @@ +// Copyright 2019 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 signalfd provides an implementation of signal file descriptors. +package signalfd + +import ( + "sync" + + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/binary" + "gvisor.dev/gvisor/pkg/sentry/context" + "gvisor.dev/gvisor/pkg/sentry/fs" + "gvisor.dev/gvisor/pkg/sentry/fs/anon" + "gvisor.dev/gvisor/pkg/sentry/fs/fsutil" + "gvisor.dev/gvisor/pkg/sentry/kernel" + "gvisor.dev/gvisor/pkg/sentry/usermem" + "gvisor.dev/gvisor/pkg/syserror" + "gvisor.dev/gvisor/pkg/waiter" +) + +// SignalOperations represent a file with signalfd semantics. +// +// +stateify savable +type SignalOperations struct { + fsutil.FileNoopRelease `state:"nosave"` + fsutil.FilePipeSeek `state:"nosave"` + fsutil.FileNotDirReaddir `state:"nosave"` + fsutil.FileNoIoctl `state:"nosave"` + fsutil.FileNoFsync `state:"nosave"` + fsutil.FileNoMMap `state:"nosave"` + fsutil.FileNoSplice `state:"nosave"` + fsutil.FileNoWrite `state:"nosave"` + fsutil.FileNoopFlush `state:"nosave"` + fsutil.FileUseInodeUnstableAttr `state:"nosave"` + + // target is the original task target. + // + // The semantics here are a bit broken. Linux will always use current + // for all reads, regardless of where the signalfd originated. We can't + // do exactly that because we need to plumb the context through + // EventRegister in order to support proper blocking behavior. This + // will undoubtedly become very complicated quickly. + target *kernel.Task + + // mu protects below. + mu sync.Mutex `state:"nosave"` + + // mask is the signal mask. Protected by mu. + mask linux.SignalSet +} + +// New creates a new signalfd object with the supplied mask. +func New(ctx context.Context, mask linux.SignalSet) (*fs.File, error) { + t := kernel.TaskFromContext(ctx) + if t == nil { + // No task context? Not valid. + return nil, syserror.EINVAL + } + // name matches fs/signalfd.c:signalfd4. + dirent := fs.NewDirent(ctx, anon.NewInode(ctx), "anon_inode:[signalfd]") + return fs.NewFile(ctx, dirent, fs.FileFlags{Read: true, Write: true}, &SignalOperations{ + target: t, + mask: mask, + }), nil +} + +// Release implements fs.FileOperations.Release. +func (s *SignalOperations) Release() {} + +// Mask returns the signal mask. +func (s *SignalOperations) Mask() linux.SignalSet { + s.mu.Lock() + mask := s.mask + s.mu.Unlock() + return mask +} + +// SetMask sets the signal mask. +func (s *SignalOperations) SetMask(mask linux.SignalSet) { + s.mu.Lock() + s.mask = mask + s.mu.Unlock() +} + +// Read implements fs.FileOperations.Read. +func (s *SignalOperations) Read(ctx context.Context, _ *fs.File, dst usermem.IOSequence, _ int64) (int64, error) { + // Attempt to dequeue relevant signals. + info, err := s.target.Sigtimedwait(s.Mask(), 0) + if err != nil { + // There must be no signal available. + return 0, syserror.ErrWouldBlock + } + + // Copy out the signal info using the specified format. + var buf [128]byte + binary.Marshal(buf[:0], usermem.ByteOrder, &linux.SignalfdSiginfo{ + Signo: uint32(info.Signo), + Errno: info.Errno, + Code: info.Code, + PID: uint32(info.Pid()), + UID: uint32(info.Uid()), + Status: info.Status(), + Overrun: uint32(info.Overrun()), + Addr: info.Addr(), + }) + n, err := dst.CopyOut(ctx, buf[:]) + return int64(n), err +} + +// Readiness implements waiter.Waitable.Readiness. +func (s *SignalOperations) Readiness(mask waiter.EventMask) waiter.EventMask { + return mask & waiter.EventIn +} + +// EventRegister implements waiter.Waitable.EventRegister. +func (s *SignalOperations) EventRegister(entry *waiter.Entry, _ waiter.EventMask) { + // Register for the signal set; ignore the passed events. + s.target.SignalRegister(entry, waiter.EventMask(s.Mask())) +} + +// EventUnregister implements waiter.Waitable.EventUnregister. +func (s *SignalOperations) EventUnregister(entry *waiter.Entry) { + // Unregister the original entry. + s.target.SignalUnregister(entry) +} diff --git a/pkg/sentry/kernel/signalfd/signalfd_state_autogen.go b/pkg/sentry/kernel/signalfd/signalfd_state_autogen.go new file mode 100755 index 000000000..66f09886d --- /dev/null +++ b/pkg/sentry/kernel/signalfd/signalfd_state_autogen.go @@ -0,0 +1,24 @@ +// automatically generated by stateify. + +package signalfd + +import ( + "gvisor.dev/gvisor/pkg/state" +) + +func (x *SignalOperations) beforeSave() {} +func (x *SignalOperations) save(m state.Map) { + x.beforeSave() + m.Save("target", &x.target) + m.Save("mask", &x.mask) +} + +func (x *SignalOperations) afterLoad() {} +func (x *SignalOperations) load(m state.Map) { + m.Load("target", &x.target) + m.Load("mask", &x.mask) +} + +func init() { + state.Register("signalfd.SignalOperations", (*SignalOperations)(nil), state.Fns{Save: (*SignalOperations).save, Load: (*SignalOperations).load}) +} diff --git a/pkg/sentry/kernel/task.go b/pkg/sentry/kernel/task.go index e91f82bb3..c82ef5486 100644 --- a/pkg/sentry/kernel/task.go +++ b/pkg/sentry/kernel/task.go @@ -35,6 +35,7 @@ import ( "gvisor.dev/gvisor/pkg/sentry/uniqueid" "gvisor.dev/gvisor/pkg/sentry/usage" "gvisor.dev/gvisor/pkg/sentry/usermem" + "gvisor.dev/gvisor/pkg/waiter" "gvisor.dev/gvisor/third_party/gvsync" ) @@ -133,6 +134,13 @@ type Task struct { // signalStack is exclusive to the task goroutine. signalStack arch.SignalStack + // signalQueue is a set of registered waiters for signal-related events. + // + // signalQueue is protected by the signalMutex. Note that the task does + // not implement all queue methods, specifically the readiness checks. + // The task only broadcast a notification on signal delivery. + signalQueue waiter.Queue `state:"zerovalue"` + // If groupStopPending is true, the task should participate in a group // stop in the interrupt path. // diff --git a/pkg/sentry/kernel/task_signals.go b/pkg/sentry/kernel/task_signals.go index 266959a07..39cd1340d 100644 --- a/pkg/sentry/kernel/task_signals.go +++ b/pkg/sentry/kernel/task_signals.go @@ -28,6 +28,7 @@ import ( ucspb "gvisor.dev/gvisor/pkg/sentry/kernel/uncaught_signal_go_proto" "gvisor.dev/gvisor/pkg/sentry/usermem" "gvisor.dev/gvisor/pkg/syserror" + "gvisor.dev/gvisor/pkg/waiter" ) // SignalAction is an internal signal action. @@ -497,6 +498,9 @@ func (tg *ThreadGroup) applySignalSideEffectsLocked(sig linux.Signal) { // // Preconditions: The signal mutex must be locked. func (t *Task) canReceiveSignalLocked(sig linux.Signal) bool { + // Notify that the signal is queued. + t.signalQueue.Notify(waiter.EventMask(linux.MakeSignalSet(sig))) + // - Do not choose tasks that are blocking the signal. if linux.SignalSetOf(sig)&t.signalMask != 0 { return false @@ -1108,3 +1112,17 @@ func (*runInterruptAfterSignalDeliveryStop) execute(t *Task) taskRunState { t.tg.signalHandlers.mu.Unlock() return t.deliverSignal(info, act) } + +// SignalRegister registers a waiter for pending signals. +func (t *Task) SignalRegister(e *waiter.Entry, mask waiter.EventMask) { + t.tg.signalHandlers.mu.Lock() + t.signalQueue.EventRegister(e, mask) + t.tg.signalHandlers.mu.Unlock() +} + +// SignalUnregister unregisters a waiter for pending signals. +func (t *Task) SignalUnregister(e *waiter.Entry) { + t.tg.signalHandlers.mu.Lock() + t.signalQueue.EventUnregister(e) + t.tg.signalHandlers.mu.Unlock() +} diff --git a/pkg/sentry/syscalls/linux/linux64.go b/pkg/sentry/syscalls/linux/linux64.go index 150999fb8..18d24ab61 100644 --- a/pkg/sentry/syscalls/linux/linux64.go +++ b/pkg/sentry/syscalls/linux/linux64.go @@ -327,14 +327,14 @@ var AMD64 = &kernel.SyscallTable{ 279: syscalls.CapError("move_pages", linux.CAP_SYS_NICE, "", nil), // requires cap_sys_nice (mostly) 280: syscalls.Supported("utimensat", Utimensat), 281: syscalls.Supported("epoll_pwait", EpollPwait), - 282: syscalls.ErrorWithEvent("signalfd", syserror.ENOSYS, "", []string{"gvisor.dev/issue/139"}), // TODO(b/19846426) + 282: syscalls.PartiallySupported("signalfd", Signalfd, "Semantics are slightly different.", []string{"gvisor.dev/issue/139"}), 283: syscalls.Supported("timerfd_create", TimerfdCreate), 284: syscalls.Supported("eventfd", Eventfd), 285: syscalls.PartiallySupported("fallocate", Fallocate, "Not all options are supported.", nil), 286: syscalls.Supported("timerfd_settime", TimerfdSettime), 287: syscalls.Supported("timerfd_gettime", TimerfdGettime), 288: syscalls.Supported("accept4", Accept4), - 289: syscalls.ErrorWithEvent("signalfd4", syserror.ENOSYS, "", []string{"gvisor.dev/issue/139"}), // TODO(b/19846426) + 289: syscalls.PartiallySupported("signalfd4", Signalfd4, "Semantics are slightly different.", []string{"gvisor.dev/issue/139"}), 290: syscalls.Supported("eventfd2", Eventfd2), 291: syscalls.Supported("epoll_create1", EpollCreate1), 292: syscalls.Supported("dup3", Dup3), diff --git a/pkg/sentry/syscalls/linux/sys_signal.go b/pkg/sentry/syscalls/linux/sys_signal.go index 0104a94c0..fb6efd5d8 100644 --- a/pkg/sentry/syscalls/linux/sys_signal.go +++ b/pkg/sentry/syscalls/linux/sys_signal.go @@ -20,7 +20,10 @@ import ( "gvisor.dev/gvisor/pkg/abi/linux" "gvisor.dev/gvisor/pkg/sentry/arch" + "gvisor.dev/gvisor/pkg/sentry/fs" "gvisor.dev/gvisor/pkg/sentry/kernel" + "gvisor.dev/gvisor/pkg/sentry/kernel/signalfd" + "gvisor.dev/gvisor/pkg/sentry/usermem" "gvisor.dev/gvisor/pkg/syserror" ) @@ -506,3 +509,77 @@ func RestartSyscall(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kerne t.Debugf("Restart block missing in restart_syscall(2). Did ptrace inject a return value of ERESTART_RESTARTBLOCK?") return 0, nil, syserror.EINTR } + +// sharedSignalfd is shared between the two calls. +func sharedSignalfd(t *kernel.Task, fd int32, sigset usermem.Addr, sigsetsize uint, flags int32) (uintptr, *kernel.SyscallControl, error) { + // Copy in the signal mask. + mask, err := copyInSigSet(t, sigset, sigsetsize) + if err != nil { + return 0, nil, err + } + + // Always check for valid flags, even if not creating. + if flags&^(linux.SFD_NONBLOCK|linux.SFD_CLOEXEC) != 0 { + return 0, nil, syserror.EINVAL + } + + // Is this a change to an existing signalfd? + // + // The spec indicates that this should adjust the mask. + if fd != -1 { + file := t.GetFile(fd) + if file == nil { + return 0, nil, syserror.EBADF + } + defer file.DecRef() + + // Is this a signalfd? + if s, ok := file.FileOperations.(*signalfd.SignalOperations); ok { + s.SetMask(mask) + return 0, nil, nil + } + + // Not a signalfd. + return 0, nil, syserror.EINVAL + } + + // Create a new file. + file, err := signalfd.New(t, mask) + if err != nil { + return 0, nil, err + } + defer file.DecRef() + + // Set appropriate flags. + file.SetFlags(fs.SettableFileFlags{ + NonBlocking: flags&linux.SFD_NONBLOCK != 0, + }) + + // Create a new descriptor. + fd, err = t.NewFDFrom(0, file, kernel.FDFlags{ + CloseOnExec: flags&linux.SFD_CLOEXEC != 0, + }) + if err != nil { + return 0, nil, err + } + + // Done. + return uintptr(fd), nil, nil +} + +// Signalfd implements the linux syscall signalfd(2). +func Signalfd(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) { + fd := args[0].Int() + sigset := args[1].Pointer() + sigsetsize := args[2].SizeT() + return sharedSignalfd(t, fd, sigset, sigsetsize, 0) +} + +// Signalfd4 implements the linux syscall signalfd4(2). +func Signalfd4(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) { + fd := args[0].Int() + sigset := args[1].Pointer() + sigsetsize := args[2].SizeT() + flags := args[3].Int() + return sharedSignalfd(t, fd, sigset, sigsetsize, flags) +} |