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-rw-r--r--pkg/sentry/kernel/pipe/pipe.go14
-rw-r--r--pkg/sentry/kernel/pipe/vfs.go63
-rw-r--r--pkg/sentry/syscalls/linux/vfs2/splice.go35
3 files changed, 75 insertions, 37 deletions
diff --git a/pkg/sentry/kernel/pipe/pipe.go b/pkg/sentry/kernel/pipe/pipe.go
index 297e8f28f..c410c96aa 100644
--- a/pkg/sentry/kernel/pipe/pipe.go
+++ b/pkg/sentry/kernel/pipe/pipe.go
@@ -200,17 +200,17 @@ type readOps struct {
//
// Precondition: this pipe must have readers.
func (p *Pipe) read(ctx context.Context, ops readOps) (int64, error) {
- // Don't block for a zero-length read even if the pipe is empty.
- if ops.left() == 0 {
- return 0, nil
- }
-
p.mu.Lock()
defer p.mu.Unlock()
return p.readLocked(ctx, ops)
}
func (p *Pipe) readLocked(ctx context.Context, ops readOps) (int64, error) {
+ // Don't block for a zero-length read even if the pipe is empty.
+ if ops.left() == 0 {
+ return 0, nil
+ }
+
// Is the pipe empty?
if p.view.Size() == 0 {
if !p.HasWriters() {
@@ -388,6 +388,10 @@ func (p *Pipe) rwReadiness() waiter.EventMask {
func (p *Pipe) queued() int64 {
p.mu.Lock()
defer p.mu.Unlock()
+ return p.queuedLocked()
+}
+
+func (p *Pipe) queuedLocked() int64 {
return p.view.Size()
}
diff --git a/pkg/sentry/kernel/pipe/vfs.go b/pkg/sentry/kernel/pipe/vfs.go
index 28f998e45..f223d59e1 100644
--- a/pkg/sentry/kernel/pipe/vfs.go
+++ b/pkg/sentry/kernel/pipe/vfs.go
@@ -244,19 +244,57 @@ func (fd *VFSPipeFD) SetPipeSize(size int64) (int64, error) {
return fd.pipe.SetFifoSize(size)
}
-// IOSequence returns a useremm.IOSequence that reads up to count bytes from,
-// or writes up to count bytes to, fd.
-func (fd *VFSPipeFD) IOSequence(count int64) usermem.IOSequence {
- return usermem.IOSequence{
+// SpliceToNonPipe performs a splice operation from fd to a non-pipe file.
+func (fd *VFSPipeFD) SpliceToNonPipe(ctx context.Context, out *vfs.FileDescription, off, count int64) (int64, error) {
+ fd.pipe.mu.Lock()
+ defer fd.pipe.mu.Unlock()
+
+ // Cap the sequence at number of bytes actually available.
+ v := fd.pipe.queuedLocked()
+ if v < count {
+ count = v
+ }
+ src := usermem.IOSequence{
IO: fd,
Addrs: usermem.AddrRangeSeqOf(usermem.AddrRange{0, usermem.Addr(count)}),
}
+
+ var (
+ n int64
+ err error
+ )
+ if off == -1 {
+ n, err = out.Write(ctx, src, vfs.WriteOptions{})
+ } else {
+ n, err = out.PWrite(ctx, src, off, vfs.WriteOptions{})
+ }
+ if n > 0 {
+ fd.pipe.view.TrimFront(n)
+ }
+ return n, err
+}
+
+// SpliceFromNonPipe performs a splice operation from a non-pipe file to fd.
+func (fd *VFSPipeFD) SpliceFromNonPipe(ctx context.Context, in *vfs.FileDescription, off, count int64) (int64, error) {
+ fd.pipe.mu.Lock()
+ defer fd.pipe.mu.Unlock()
+
+ dst := usermem.IOSequence{
+ IO: fd,
+ Addrs: usermem.AddrRangeSeqOf(usermem.AddrRange{0, usermem.Addr(count)}),
+ }
+
+ if off == -1 {
+ return in.Read(ctx, dst, vfs.ReadOptions{})
+ }
+ return in.PRead(ctx, dst, off, vfs.ReadOptions{})
}
-// CopyIn implements usermem.IO.CopyIn.
+// CopyIn implements usermem.IO.CopyIn. Note that it is the caller's
+// responsibility to trim fd.pipe.view after the read is completed.
func (fd *VFSPipeFD) CopyIn(ctx context.Context, addr usermem.Addr, dst []byte, opts usermem.IOOpts) (int, error) {
origCount := int64(len(dst))
- n, err := fd.pipe.read(ctx, readOps{
+ n, err := fd.pipe.readLocked(ctx, readOps{
left: func() int64 {
return int64(len(dst))
},
@@ -265,7 +303,6 @@ func (fd *VFSPipeFD) CopyIn(ctx context.Context, addr usermem.Addr, dst []byte,
},
read: func(view *buffer.View) (int64, error) {
n, err := view.ReadAt(dst, 0)
- view.TrimFront(int64(n))
return int64(n), err
},
})
@@ -281,7 +318,7 @@ func (fd *VFSPipeFD) CopyIn(ctx context.Context, addr usermem.Addr, dst []byte,
// CopyOut implements usermem.IO.CopyOut.
func (fd *VFSPipeFD) CopyOut(ctx context.Context, addr usermem.Addr, src []byte, opts usermem.IOOpts) (int, error) {
origCount := int64(len(src))
- n, err := fd.pipe.write(ctx, writeOps{
+ n, err := fd.pipe.writeLocked(ctx, writeOps{
left: func() int64 {
return int64(len(src))
},
@@ -305,7 +342,7 @@ func (fd *VFSPipeFD) CopyOut(ctx context.Context, addr usermem.Addr, src []byte,
// ZeroOut implements usermem.IO.ZeroOut.
func (fd *VFSPipeFD) ZeroOut(ctx context.Context, addr usermem.Addr, toZero int64, opts usermem.IOOpts) (int64, error) {
origCount := toZero
- n, err := fd.pipe.write(ctx, writeOps{
+ n, err := fd.pipe.writeLocked(ctx, writeOps{
left: func() int64 {
return toZero
},
@@ -326,14 +363,15 @@ func (fd *VFSPipeFD) ZeroOut(ctx context.Context, addr usermem.Addr, toZero int6
return n, err
}
-// CopyInTo implements usermem.IO.CopyInTo.
+// CopyInTo implements usermem.IO.CopyInTo. Note that it is the caller's
+// responsibility to trim fd.pipe.view after the read is completed.
func (fd *VFSPipeFD) CopyInTo(ctx context.Context, ars usermem.AddrRangeSeq, dst safemem.Writer, opts usermem.IOOpts) (int64, error) {
count := ars.NumBytes()
if count == 0 {
return 0, nil
}
origCount := count
- n, err := fd.pipe.read(ctx, readOps{
+ n, err := fd.pipe.readLocked(ctx, readOps{
left: func() int64 {
return count
},
@@ -342,7 +380,6 @@ func (fd *VFSPipeFD) CopyInTo(ctx context.Context, ars usermem.AddrRangeSeq, dst
},
read: func(view *buffer.View) (int64, error) {
n, err := view.ReadToSafememWriter(dst, uint64(count))
- view.TrimFront(int64(n))
return int64(n), err
},
})
@@ -362,7 +399,7 @@ func (fd *VFSPipeFD) CopyOutFrom(ctx context.Context, ars usermem.AddrRangeSeq,
return 0, nil
}
origCount := count
- n, err := fd.pipe.write(ctx, writeOps{
+ n, err := fd.pipe.writeLocked(ctx, writeOps{
left: func() int64 {
return count
},
diff --git a/pkg/sentry/syscalls/linux/vfs2/splice.go b/pkg/sentry/syscalls/linux/vfs2/splice.go
index 75bfa2c79..192411393 100644
--- a/pkg/sentry/syscalls/linux/vfs2/splice.go
+++ b/pkg/sentry/syscalls/linux/vfs2/splice.go
@@ -131,18 +131,14 @@ func Splice(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscal
case inIsPipe && outIsPipe:
n, err = pipe.Splice(t, outPipeFD, inPipeFD, count)
case inIsPipe:
+ n, err = inPipeFD.SpliceToNonPipe(t, outFile, outOffset, count)
if outOffset != -1 {
- n, err = outFile.PWrite(t, inPipeFD.IOSequence(count), outOffset, vfs.WriteOptions{})
outOffset += n
- } else {
- n, err = outFile.Write(t, inPipeFD.IOSequence(count), vfs.WriteOptions{})
}
case outIsPipe:
+ n, err = outPipeFD.SpliceFromNonPipe(t, inFile, inOffset, count)
if inOffset != -1 {
- n, err = inFile.PRead(t, outPipeFD.IOSequence(count), inOffset, vfs.ReadOptions{})
inOffset += n
- } else {
- n, err = inFile.Read(t, outPipeFD.IOSequence(count), vfs.ReadOptions{})
}
default:
panic("not possible")
@@ -341,17 +337,15 @@ func Sendfile(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sysc
if outIsPipe {
for n < count {
var spliceN int64
- if offset != -1 {
- spliceN, err = inFile.PRead(t, outPipeFD.IOSequence(count), offset, vfs.ReadOptions{})
- offset += spliceN
- } else {
- spliceN, err = inFile.Read(t, outPipeFD.IOSequence(count), vfs.ReadOptions{})
- }
+ spliceN, err = outPipeFD.SpliceFromNonPipe(t, inFile, offset, count)
if spliceN == 0 && err == io.EOF {
// We reached the end of the file. Eat the error and exit the loop.
err = nil
break
}
+ if offset != -1 {
+ offset += spliceN
+ }
n += spliceN
if err == syserror.ErrWouldBlock && !nonBlock {
err = dw.waitForBoth(t)
@@ -371,19 +365,18 @@ func Sendfile(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sysc
} else {
readN, err = inFile.Read(t, usermem.BytesIOSequence(buf), vfs.ReadOptions{})
}
- if readN == 0 && err == io.EOF {
- // We reached the end of the file. Eat the error and exit the loop.
- err = nil
+ if readN == 0 && err != nil {
+ if err == io.EOF {
+ // We reached the end of the file. Eat the error before exiting the loop.
+ err = nil
+ }
break
}
n += readN
- if err != nil {
- break
- }
// Write all of the bytes that we read. This may need
// multiple write calls to complete.
- wbuf := buf[:n]
+ wbuf := buf[:readN]
for len(wbuf) > 0 {
var writeN int64
writeN, err = outFile.Write(t, usermem.BytesIOSequence(wbuf), vfs.WriteOptions{})
@@ -398,6 +391,10 @@ func Sendfile(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sysc
notWritten := int64(len(wbuf))
n -= notWritten
if offset != -1 {
+ // TODO(gvisor.dev/issue/3779): The inFile offset will be incorrect if we
+ // roll back, because it has already been advanced by the full amount.
+ // Merely seeking on inFile does not work, because there may be concurrent
+ // file operations.
offset -= notWritten
}
break
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-06 20:39:41 +0000