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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 vfs2
import (
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/context"
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/fsimpl/eventfd"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/mm"
slinux "gvisor.dev/gvisor/pkg/sentry/syscalls/linux"
"gvisor.dev/gvisor/pkg/sentry/vfs"
"gvisor.dev/gvisor/pkg/syserror"
"gvisor.dev/gvisor/pkg/usermem"
)
// IoSubmit implements linux syscall io_submit(2).
func IoSubmit(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
id := args[0].Uint64()
nrEvents := args[1].Int()
addr := args[2].Pointer()
if nrEvents < 0 {
return 0, nil, syserror.EINVAL
}
for i := int32(0); i < nrEvents; i++ {
// Copy in the address.
cbAddrNative := t.Arch().Native(0)
if _, err := t.CopyIn(addr, cbAddrNative); err != nil {
if i > 0 {
// Some successful.
return uintptr(i), nil, nil
}
// Nothing done.
return 0, nil, err
}
// Copy in this callback.
var cb linux.IOCallback
cbAddr := usermem.Addr(t.Arch().Value(cbAddrNative))
if _, err := t.CopyIn(cbAddr, &cb); err != nil {
if i > 0 {
// Some have been successful.
return uintptr(i), nil, nil
}
// Nothing done.
return 0, nil, err
}
// Process this callback.
if err := submitCallback(t, id, &cb, cbAddr); err != nil {
if i > 0 {
// Partial success.
return uintptr(i), nil, nil
}
// Nothing done.
return 0, nil, err
}
// Advance to the next one.
addr += usermem.Addr(t.Arch().Width())
}
return uintptr(nrEvents), nil, nil
}
// submitCallback processes a single callback.
func submitCallback(t *kernel.Task, id uint64, cb *linux.IOCallback, cbAddr usermem.Addr) error {
if cb.Reserved2 != 0 {
return syserror.EINVAL
}
fd := t.GetFileVFS2(cb.FD)
if fd == nil {
return syserror.EBADF
}
defer fd.DecRef(t)
// Was there an eventFD? Extract it.
var eventFD *vfs.FileDescription
if cb.Flags&linux.IOCB_FLAG_RESFD != 0 {
eventFD = t.GetFileVFS2(cb.ResFD)
if eventFD == nil {
return syserror.EBADF
}
defer eventFD.DecRef(t)
// Check that it is an eventfd.
if _, ok := eventFD.Impl().(*eventfd.EventFileDescription); !ok {
return syserror.EINVAL
}
}
ioseq, err := memoryFor(t, cb)
if err != nil {
return err
}
// Check offset for reads/writes.
switch cb.OpCode {
case linux.IOCB_CMD_PREAD, linux.IOCB_CMD_PREADV, linux.IOCB_CMD_PWRITE, linux.IOCB_CMD_PWRITEV:
if cb.Offset < 0 {
return syserror.EINVAL
}
}
// Prepare the request.
aioCtx, ok := t.MemoryManager().LookupAIOContext(t, id)
if !ok {
return syserror.EINVAL
}
if ready := aioCtx.Prepare(); !ready {
// Context is busy.
return syserror.EAGAIN
}
if eventFD != nil {
// The request is set. Make sure there's a ref on the file.
//
// This is necessary when the callback executes on completion,
// which is also what will release this reference.
eventFD.IncRef()
}
// Perform the request asynchronously.
fd.IncRef()
t.QueueAIO(getAIOCallback(t, fd, eventFD, cbAddr, cb, ioseq, aioCtx))
return nil
}
func getAIOCallback(t *kernel.Task, fd, eventFD *vfs.FileDescription, cbAddr usermem.Addr, cb *linux.IOCallback, ioseq usermem.IOSequence, aioCtx *mm.AIOContext) kernel.AIOCallback {
return func(ctx context.Context) {
// Release references after completing the callback.
defer fd.DecRef(ctx)
if eventFD != nil {
defer eventFD.DecRef(ctx)
}
if aioCtx.Dead() {
aioCtx.CancelPendingRequest()
return
}
ev := &linux.IOEvent{
Data: cb.Data,
Obj: uint64(cbAddr),
}
var err error
switch cb.OpCode {
case linux.IOCB_CMD_PREAD, linux.IOCB_CMD_PREADV:
ev.Result, err = fd.PRead(ctx, ioseq, cb.Offset, vfs.ReadOptions{})
case linux.IOCB_CMD_PWRITE, linux.IOCB_CMD_PWRITEV:
ev.Result, err = fd.PWrite(ctx, ioseq, cb.Offset, vfs.WriteOptions{})
case linux.IOCB_CMD_FSYNC, linux.IOCB_CMD_FDSYNC:
err = fd.Sync(ctx)
}
// Update the result.
if err != nil {
err = slinux.HandleIOErrorVFS2(t, ev.Result != 0 /* partial */, err, nil /* never interrupted */, "aio", fd)
ev.Result = -int64(kernel.ExtractErrno(err, 0))
}
// Queue the result for delivery.
aioCtx.FinishRequest(ev)
// Notify the event file if one was specified. This needs to happen
// *after* queueing the result to avoid racing with the thread we may
// wake up.
if eventFD != nil {
eventFD.Impl().(*eventfd.EventFileDescription).Signal(1)
}
}
}
// memoryFor returns appropriate memory for the given callback.
func memoryFor(t *kernel.Task, cb *linux.IOCallback) (usermem.IOSequence, error) {
bytes := int(cb.Bytes)
if bytes < 0 {
// Linux also requires that this field fit in ssize_t.
return usermem.IOSequence{}, syserror.EINVAL
}
// Since this I/O will be asynchronous with respect to t's task goroutine,
// we have no guarantee that t's AddressSpace will be active during the
// I/O.
switch cb.OpCode {
case linux.IOCB_CMD_PREAD, linux.IOCB_CMD_PWRITE:
return t.SingleIOSequence(usermem.Addr(cb.Buf), bytes, usermem.IOOpts{
AddressSpaceActive: false,
})
case linux.IOCB_CMD_PREADV, linux.IOCB_CMD_PWRITEV:
return t.IovecsIOSequence(usermem.Addr(cb.Buf), bytes, usermem.IOOpts{
AddressSpaceActive: false,
})
case linux.IOCB_CMD_FSYNC, linux.IOCB_CMD_FDSYNC, linux.IOCB_CMD_NOOP:
return usermem.IOSequence{}, nil
default:
// Not a supported command.
return usermem.IOSequence{}, syserror.EINVAL
}
}
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