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-rw-r--r--pkg/sentry/syscalls/linux/sys_eventfd.go17
-rwxr-xr-xpkg/sentry/syscalls/linux/vfs2/eventfd.go59
-rwxr-xr-xpkg/sentry/syscalls/linux/vfs2/linux64_override_amd64.go4
-rwxr-xr-xpkg/sentry/syscalls/linux/vfs2/timerfd.go (renamed from pkg/sentry/syscalls/linux/vfs2/sys_timerfd.go)0
-rwxr-xr-xpkg/sentry/vfs/eventfd.go282
5 files changed, 348 insertions, 14 deletions
diff --git a/pkg/sentry/syscalls/linux/sys_eventfd.go b/pkg/sentry/syscalls/linux/sys_eventfd.go
index 8a34c4e99..ed3413ca6 100644
--- a/pkg/sentry/syscalls/linux/sys_eventfd.go
+++ b/pkg/sentry/syscalls/linux/sys_eventfd.go
@@ -15,6 +15,7 @@
package linux
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"
@@ -22,32 +23,24 @@ import (
"gvisor.dev/gvisor/pkg/syserror"
)
-const (
- // EFD_SEMAPHORE is a flag used in syscall eventfd(2) and eventfd2(2). Please
- // see its man page for more information.
- EFD_SEMAPHORE = 1
- EFD_NONBLOCK = 0x800
- EFD_CLOEXEC = 0x80000
-)
-
// Eventfd2 implements linux syscall eventfd2(2).
func Eventfd2(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
initVal := args[0].Int()
flags := uint(args[1].Uint())
- allOps := uint(EFD_SEMAPHORE | EFD_NONBLOCK | EFD_CLOEXEC)
+ allOps := uint(linux.EFD_SEMAPHORE | linux.EFD_NONBLOCK | linux.EFD_CLOEXEC)
if flags & ^allOps != 0 {
return 0, nil, syserror.EINVAL
}
- event := eventfd.New(t, uint64(initVal), flags&EFD_SEMAPHORE != 0)
+ event := eventfd.New(t, uint64(initVal), flags&linux.EFD_SEMAPHORE != 0)
event.SetFlags(fs.SettableFileFlags{
- NonBlocking: flags&EFD_NONBLOCK != 0,
+ NonBlocking: flags&linux.EFD_NONBLOCK != 0,
})
defer event.DecRef()
fd, err := t.NewFDFrom(0, event, kernel.FDFlags{
- CloseOnExec: flags&EFD_CLOEXEC != 0,
+ CloseOnExec: flags&linux.EFD_CLOEXEC != 0,
})
if err != nil {
return 0, nil, err
diff --git a/pkg/sentry/syscalls/linux/vfs2/eventfd.go b/pkg/sentry/syscalls/linux/vfs2/eventfd.go
new file mode 100755
index 000000000..bd2194972
--- /dev/null
+++ b/pkg/sentry/syscalls/linux/vfs2/eventfd.go
@@ -0,0 +1,59 @@
+// 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 vfs2
+
+import (
+ "gvisor.dev/gvisor/pkg/abi/linux"
+ "gvisor.dev/gvisor/pkg/sentry/arch"
+ "gvisor.dev/gvisor/pkg/sentry/kernel"
+ "gvisor.dev/gvisor/pkg/syserror"
+)
+
+// Eventfd2 implements linux syscall eventfd2(2).
+func Eventfd2(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+ initVal := uint64(args[0].Uint())
+ flags := uint(args[1].Uint())
+ allOps := uint(linux.EFD_SEMAPHORE | linux.EFD_NONBLOCK | linux.EFD_CLOEXEC)
+
+ if flags & ^allOps != 0 {
+ return 0, nil, syserror.EINVAL
+ }
+
+ fileFlags := uint32(linux.O_RDWR)
+ if flags&linux.EFD_NONBLOCK != 0 {
+ fileFlags |= linux.O_NONBLOCK
+ }
+ semMode := flags&linux.EFD_SEMAPHORE != 0
+ eventfd, err := t.Kernel().VFS().NewEventFD(initVal, semMode, fileFlags)
+ if err != nil {
+ return 0, nil, err
+ }
+ defer eventfd.DecRef()
+
+ fd, err := t.NewFDFromVFS2(0, eventfd, kernel.FDFlags{
+ CloseOnExec: flags&linux.EFD_CLOEXEC != 0,
+ })
+ if err != nil {
+ return 0, nil, err
+ }
+
+ return uintptr(fd), nil, nil
+}
+
+// Eventfd implements linux syscall eventfd(2).
+func Eventfd(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+ args[1].Value = 0
+ return Eventfd2(t, args)
+}
diff --git a/pkg/sentry/syscalls/linux/vfs2/linux64_override_amd64.go b/pkg/sentry/syscalls/linux/vfs2/linux64_override_amd64.go
index 74920f785..074f58e5d 100755
--- a/pkg/sentry/syscalls/linux/vfs2/linux64_override_amd64.go
+++ b/pkg/sentry/syscalls/linux/vfs2/linux64_override_amd64.go
@@ -141,14 +141,14 @@ func Override(table map[uintptr]kernel.Syscall) {
table[281] = syscalls.Supported("epoll_pwait", EpollPwait)
delete(table, 282) // signalfd
table[283] = syscalls.Supported("timerfd_create", TimerfdCreate)
- delete(table, 284) // eventfd
+ table[284] = syscalls.Supported("eventfd", Eventfd)
delete(table, 285) // fallocate
table[286] = syscalls.Supported("timerfd_settime", TimerfdSettime)
table[287] = syscalls.Supported("timerfd_gettime", TimerfdGettime)
// TODO(gvisor.dev/issue/1485): Port all socket variants to VFS2.
table[288] = syscalls.PartiallySupported("accept4", Accept4, "In process of porting socket syscalls to VFS2.", nil)
delete(table, 289) // signalfd4
- delete(table, 290) // eventfd2
+ table[290] = syscalls.Supported("eventfd2", Eventfd2)
table[291] = syscalls.Supported("epoll_create1", EpollCreate1)
table[292] = syscalls.Supported("dup3", Dup3)
table[293] = syscalls.Supported("pipe2", Pipe2)
diff --git a/pkg/sentry/syscalls/linux/vfs2/sys_timerfd.go b/pkg/sentry/syscalls/linux/vfs2/timerfd.go
index 7938a5249..7938a5249 100755
--- a/pkg/sentry/syscalls/linux/vfs2/sys_timerfd.go
+++ b/pkg/sentry/syscalls/linux/vfs2/timerfd.go
diff --git a/pkg/sentry/vfs/eventfd.go b/pkg/sentry/vfs/eventfd.go
new file mode 100755
index 000000000..f39dacacf
--- /dev/null
+++ b/pkg/sentry/vfs/eventfd.go
@@ -0,0 +1,282 @@
+// Copyright 2020 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 vfs
+
+import (
+ "math"
+ "sync"
+ "syscall"
+
+ "gvisor.dev/gvisor/pkg/abi/linux"
+ "gvisor.dev/gvisor/pkg/context"
+ "gvisor.dev/gvisor/pkg/fdnotifier"
+ "gvisor.dev/gvisor/pkg/log"
+ "gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
+ "gvisor.dev/gvisor/pkg/waiter"
+)
+
+// EventFileDescription implements FileDescriptionImpl for file-based event
+// notification (eventfd). Eventfds are usually internal to the Sentry but in
+// certain situations they may be converted into a host-backed eventfd.
+type EventFileDescription struct {
+ vfsfd FileDescription
+ FileDescriptionDefaultImpl
+ DentryMetadataFileDescriptionImpl
+
+ // queue is used to notify interested parties when the event object
+ // becomes readable or writable.
+ queue waiter.Queue `state:"zerovalue"`
+
+ // mu protects the fields below.
+ mu sync.Mutex `state:"nosave"`
+
+ // val is the current value of the event counter.
+ val uint64
+
+ // semMode specifies whether the event is in "semaphore" mode.
+ semMode bool
+
+ // hostfd indicates whether this eventfd is passed through to the host.
+ hostfd int
+}
+
+var _ FileDescriptionImpl = (*EventFileDescription)(nil)
+
+// NewEventFD creates a new event fd.
+func (vfs *VirtualFilesystem) NewEventFD(initVal uint64, semMode bool, flags uint32) (*FileDescription, error) {
+ vd := vfs.NewAnonVirtualDentry("[eventfd]")
+ defer vd.DecRef()
+ efd := &EventFileDescription{
+ val: initVal,
+ semMode: semMode,
+ hostfd: -1,
+ }
+ if err := efd.vfsfd.Init(efd, flags, vd.Mount(), vd.Dentry(), &FileDescriptionOptions{
+ UseDentryMetadata: true,
+ DenyPRead: true,
+ DenyPWrite: true,
+ }); err != nil {
+ return nil, err
+ }
+ return &efd.vfsfd, nil
+}
+
+// HostFD returns the host eventfd associated with this event.
+func (efd *EventFileDescription) HostFD() (int, error) {
+ efd.mu.Lock()
+ defer efd.mu.Unlock()
+ if efd.hostfd >= 0 {
+ return efd.hostfd, nil
+ }
+
+ flags := linux.EFD_NONBLOCK
+ if efd.semMode {
+ flags |= linux.EFD_SEMAPHORE
+ }
+
+ fd, _, errno := syscall.Syscall(syscall.SYS_EVENTFD2, uintptr(efd.val), uintptr(flags), 0)
+ if errno != 0 {
+ return -1, errno
+ }
+
+ if err := fdnotifier.AddFD(int32(fd), &efd.queue); err != nil {
+ if closeErr := syscall.Close(int(fd)); closeErr != nil {
+ log.Warningf("close(%d) eventfd failed: %v", fd, closeErr)
+ }
+ return -1, err
+ }
+
+ efd.hostfd = int(fd)
+ return efd.hostfd, nil
+}
+
+// Release implements FileDescriptionImpl.Release()
+func (efd *EventFileDescription) Release() {
+ efd.mu.Lock()
+ defer efd.mu.Unlock()
+ if efd.hostfd >= 0 {
+ fdnotifier.RemoveFD(int32(efd.hostfd))
+ if closeErr := syscall.Close(int(efd.hostfd)); closeErr != nil {
+ log.Warningf("close(%d) eventfd failed: %v", efd.hostfd, closeErr)
+ }
+ efd.hostfd = -1
+ }
+}
+
+// Read implements FileDescriptionImpl.Read.
+func (efd *EventFileDescription) Read(ctx context.Context, dst usermem.IOSequence, _ ReadOptions) (int64, error) {
+ if dst.NumBytes() < 8 {
+ return 0, syscall.EINVAL
+ }
+ if err := efd.read(ctx, dst); err != nil {
+ return 0, err
+ }
+ return 8, nil
+}
+
+// Write implements FileDescriptionImpl.Write.
+func (efd *EventFileDescription) Write(ctx context.Context, src usermem.IOSequence, _ WriteOptions) (int64, error) {
+ if src.NumBytes() < 8 {
+ return 0, syscall.EINVAL
+ }
+ if err := efd.write(ctx, src); err != nil {
+ return 0, err
+ }
+ return 8, nil
+}
+
+// Preconditions: Must be called with efd.mu locked.
+func (efd *EventFileDescription) hostReadLocked(ctx context.Context, dst usermem.IOSequence) error {
+ var buf [8]byte
+ if _, err := syscall.Read(efd.hostfd, buf[:]); err != nil {
+ if err == syscall.EWOULDBLOCK {
+ return syserror.ErrWouldBlock
+ }
+ return err
+ }
+ _, err := dst.CopyOut(ctx, buf[:])
+ return err
+}
+
+func (efd *EventFileDescription) read(ctx context.Context, dst usermem.IOSequence) error {
+ efd.mu.Lock()
+ if efd.hostfd >= 0 {
+ defer efd.mu.Unlock()
+ return efd.hostReadLocked(ctx, dst)
+ }
+
+ // We can't complete the read if the value is currently zero.
+ if efd.val == 0 {
+ efd.mu.Unlock()
+ return syserror.ErrWouldBlock
+ }
+
+ // Update the value based on the mode the event is operating in.
+ var val uint64
+ if efd.semMode {
+ val = 1
+ // Consistent with Linux, this is done even if writing to memory fails.
+ efd.val--
+ } else {
+ val = efd.val
+ efd.val = 0
+ }
+
+ efd.mu.Unlock()
+
+ // Notify writers. We do this even if we were already writable because
+ // it is possible that a writer is waiting to write the maximum value
+ // to the event.
+ efd.queue.Notify(waiter.EventOut)
+
+ var buf [8]byte
+ usermem.ByteOrder.PutUint64(buf[:], val)
+ _, err := dst.CopyOut(ctx, buf[:])
+ return err
+}
+
+// Preconditions: Must be called with efd.mu locked.
+func (efd *EventFileDescription) hostWriteLocked(val uint64) error {
+ var buf [8]byte
+ usermem.ByteOrder.PutUint64(buf[:], val)
+ _, err := syscall.Write(efd.hostfd, buf[:])
+ if err == syscall.EWOULDBLOCK {
+ return syserror.ErrWouldBlock
+ }
+ return err
+}
+
+func (efd *EventFileDescription) write(ctx context.Context, src usermem.IOSequence) error {
+ var buf [8]byte
+ if _, err := src.CopyIn(ctx, buf[:]); err != nil {
+ return err
+ }
+ val := usermem.ByteOrder.Uint64(buf[:])
+
+ return efd.Signal(val)
+}
+
+// Signal is an internal function to signal the event fd.
+func (efd *EventFileDescription) Signal(val uint64) error {
+ if val == math.MaxUint64 {
+ return syscall.EINVAL
+ }
+
+ efd.mu.Lock()
+
+ if efd.hostfd >= 0 {
+ defer efd.mu.Unlock()
+ return efd.hostWriteLocked(val)
+ }
+
+ // We only allow writes that won't cause the value to go over the max
+ // uint64 minus 1.
+ if val > math.MaxUint64-1-efd.val {
+ efd.mu.Unlock()
+ return syserror.ErrWouldBlock
+ }
+
+ efd.val += val
+ efd.mu.Unlock()
+
+ // Always trigger a notification.
+ efd.queue.Notify(waiter.EventIn)
+
+ return nil
+}
+
+// Readiness implements waiter.Waitable.Readiness.
+func (efd *EventFileDescription) Readiness(mask waiter.EventMask) waiter.EventMask {
+ efd.mu.Lock()
+ defer efd.mu.Unlock()
+
+ if efd.hostfd >= 0 {
+ return fdnotifier.NonBlockingPoll(int32(efd.hostfd), mask)
+ }
+
+ ready := waiter.EventMask(0)
+ if efd.val > 0 {
+ ready |= waiter.EventIn
+ }
+
+ if efd.val < math.MaxUint64-1 {
+ ready |= waiter.EventOut
+ }
+
+ return mask & ready
+}
+
+// EventRegister implements waiter.Waitable.EventRegister.
+func (efd *EventFileDescription) EventRegister(entry *waiter.Entry, mask waiter.EventMask) {
+ efd.queue.EventRegister(entry, mask)
+
+ efd.mu.Lock()
+ defer efd.mu.Unlock()
+ if efd.hostfd >= 0 {
+ fdnotifier.UpdateFD(int32(efd.hostfd))
+ }
+}
+
+// EventUnregister implements waiter.Waitable.EventUnregister.
+func (efd *EventFileDescription) EventUnregister(entry *waiter.Entry) {
+ efd.queue.EventUnregister(entry)
+
+ efd.mu.Lock()
+ defer efd.mu.Unlock()
+ if efd.hostfd >= 0 {
+ fdnotifier.UpdateFD(int32(efd.hostfd))
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-01 07:35:14 +0000