142 lines
4.3 KiB
Go
142 lines
4.3 KiB
Go
// Copyright 2020 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package fdimport provides the Import function.
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package fdimport
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import (
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"fmt"
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"gvisor.dev/gvisor/pkg/context"
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"gvisor.dev/gvisor/pkg/fd"
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"gvisor.dev/gvisor/pkg/sentry/fs"
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"gvisor.dev/gvisor/pkg/sentry/fs/host"
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hostvfs2 "gvisor.dev/gvisor/pkg/sentry/fsimpl/host"
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"gvisor.dev/gvisor/pkg/sentry/kernel"
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"gvisor.dev/gvisor/pkg/sentry/vfs"
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)
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// Import imports a slice of FDs into the given FDTable. If console is true,
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// sets up TTY for the first 3 FDs in the slice representing stdin, stdout,
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// stderr. Used FDs are either closed or released. It's safe for the caller to
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// close any remaining files upon return.
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func Import(ctx context.Context, fdTable *kernel.FDTable, console bool, fds []*fd.FD) (*host.TTYFileOperations, *hostvfs2.TTYFileDescription, error) {
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if kernel.VFS2Enabled {
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ttyFile, err := importVFS2(ctx, fdTable, console, fds)
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return nil, ttyFile, err
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}
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ttyFile, err := importFS(ctx, fdTable, console, fds)
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return ttyFile, nil, err
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}
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func importFS(ctx context.Context, fdTable *kernel.FDTable, console bool, fds []*fd.FD) (*host.TTYFileOperations, error) {
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var ttyFile *fs.File
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for appFD, hostFD := range fds {
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var appFile *fs.File
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if console && appFD < 3 {
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// Import the file as a host TTY file.
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if ttyFile == nil {
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var err error
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appFile, err = host.ImportFile(ctx, hostFD.FD(), true /* isTTY */)
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if err != nil {
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return nil, err
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}
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defer appFile.DecRef(ctx)
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_ = hostFD.Close() // FD is dup'd i ImportFile.
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// Remember this in the TTY file, as we will
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// use it for the other stdio FDs.
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ttyFile = appFile
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} else {
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// Re-use the existing TTY file, as all three
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// stdio FDs must point to the same fs.File in
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// order to share TTY state, specifically the
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// foreground process group id.
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appFile = ttyFile
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}
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} else {
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// Import the file as a regular host file.
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var err error
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appFile, err = host.ImportFile(ctx, hostFD.FD(), false /* isTTY */)
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if err != nil {
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return nil, err
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}
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defer appFile.DecRef(ctx)
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_ = hostFD.Close() // FD is dup'd i ImportFile.
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}
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// Add the file to the FD map.
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if err := fdTable.NewFDAt(ctx, int32(appFD), appFile, kernel.FDFlags{}); err != nil {
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return nil, err
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}
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}
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if ttyFile == nil {
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return nil, nil
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}
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return ttyFile.FileOperations.(*host.TTYFileOperations), nil
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}
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func importVFS2(ctx context.Context, fdTable *kernel.FDTable, console bool, stdioFDs []*fd.FD) (*hostvfs2.TTYFileDescription, error) {
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k := kernel.KernelFromContext(ctx)
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if k == nil {
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return nil, fmt.Errorf("cannot find kernel from context")
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}
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var ttyFile *vfs.FileDescription
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for appFD, hostFD := range stdioFDs {
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var appFile *vfs.FileDescription
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if console && appFD < 3 {
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// Import the file as a host TTY file.
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if ttyFile == nil {
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var err error
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appFile, err = hostvfs2.ImportFD(ctx, k.HostMount(), hostFD.FD(), true /* isTTY */)
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if err != nil {
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return nil, err
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}
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defer appFile.DecRef(ctx)
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hostFD.Release() // FD is transfered to host FD.
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// Remember this in the TTY file, as we will use it for the other stdio
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// FDs.
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ttyFile = appFile
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} else {
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// Re-use the existing TTY file, as all three stdio FDs must point to
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// the same fs.File in order to share TTY state, specifically the
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// foreground process group id.
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appFile = ttyFile
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}
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} else {
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var err error
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appFile, err = hostvfs2.ImportFD(ctx, k.HostMount(), hostFD.FD(), false /* isTTY */)
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if err != nil {
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return nil, err
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}
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defer appFile.DecRef(ctx)
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hostFD.Release() // FD is transfered to host FD.
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}
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if err := fdTable.NewFDAtVFS2(ctx, int32(appFD), appFile, kernel.FDFlags{}); err != nil {
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return nil, err
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}
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}
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if ttyFile == nil {
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return nil, nil
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}
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return ttyFile.Impl().(*hostvfs2.TTYFileDescription), nil
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}
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