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// Copyright 2018 Google Inc.
//
// 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 cmd
import (
"os"
"runtime"
"runtime/debug"
"strings"
"syscall"
"context"
"flag"
"github.com/google/subcommands"
specs "github.com/opencontainers/runtime-spec/specs-go"
"gvisor.googlesource.com/gvisor/pkg/log"
"gvisor.googlesource.com/gvisor/runsc/boot"
"gvisor.googlesource.com/gvisor/runsc/specutils"
)
// Boot implements subcommands.Command for the "boot" command which starts a
// new sandbox. It should not be called directly.
type Boot struct {
// bundleDir is the path to the bundle directory.
bundleDir string
// controllerFD is the file descriptor of a stream socket for the
// control server that is donated to this process.
controllerFD int
// ioFDs is the list of FDs used to connect to FS gofers.
ioFDs intFlags
// console is set to true if the sandbox should allow terminal ioctl(2)
// syscalls.
console bool
// applyCaps determines if capabilities defined in the spec should be applied
// to the process.
applyCaps bool
}
// Name implements subcommands.Command.Name.
func (*Boot) Name() string {
return "boot"
}
// Synopsis implements subcommands.Command.Synopsis.
func (*Boot) Synopsis() string {
return "launch a sandbox process (internal use only)"
}
// Usage implements subcommands.Command.Usage.
func (*Boot) Usage() string {
return `boot [flags]`
}
// SetFlags implements subcommands.Command.SetFlags.
func (b *Boot) SetFlags(f *flag.FlagSet) {
f.StringVar(&b.bundleDir, "bundle", "", "required path to the root of the bundle directory")
f.IntVar(&b.controllerFD, "controller-fd", -1, "required FD of a stream socket for the control server that must be donated to this process")
f.Var(&b.ioFDs, "io-fds", "list of FDs to connect 9P clients. They must follow this order: root first, then mounts as defined in the spec")
f.BoolVar(&b.console, "console", false, "set to true if the sandbox should allow terminal ioctl(2) syscalls")
f.BoolVar(&b.applyCaps, "apply-caps", false, "if true, apply capabilities defined in the spec to the process")
}
// Execute implements subcommands.Command.Execute. It starts a sandbox in a
// waiting state.
func (b *Boot) Execute(_ context.Context, f *flag.FlagSet, args ...interface{}) subcommands.ExitStatus {
if b.bundleDir == "" || b.controllerFD == -1 || f.NArg() != 0 {
f.Usage()
return subcommands.ExitUsageError
}
// Ensure that if there is a panic, all goroutine stacks are printed.
debug.SetTraceback("all")
// Get the spec from the bundleDir.
spec, err := specutils.ReadSpec(b.bundleDir)
if err != nil {
Fatalf("error reading spec: %v", err)
}
specutils.LogSpec(spec)
// Turn any relative paths in the spec to absolute by prepending the bundleDir.
spec.Root.Path = absPath(b.bundleDir, spec.Root.Path)
for _, m := range spec.Mounts {
if m.Source != "" {
m.Source = absPath(b.bundleDir, m.Source)
}
}
conf := args[0].(*boot.Config)
waitStatus := args[1].(*syscall.WaitStatus)
if b.applyCaps {
setCapsAndCallSelf(conf, spec)
Fatalf("setCapsAndCallSelf must never return")
}
// Create the loader.
l, err := boot.New(spec, conf, b.controllerFD, b.ioFDs.GetArray(), b.console)
if err != nil {
Fatalf("error creating loader: %v", err)
}
defer l.Destroy()
// Wait for the start signal from runsc.
l.WaitForStartSignal()
// Run the application and wait for it to finish.
if err := l.Run(); err != nil {
Fatalf("error running sandbox: %v", err)
}
ws := l.WaitExit()
log.Infof("application exiting with %+v", ws)
*waitStatus = syscall.WaitStatus(ws.Status())
return subcommands.ExitSuccess
}
// setCapsAndCallSelf sets capabilities to the current thread and then execve's
// itself again with the same arguments except '--apply-caps' to restart the
// whole process with the desired capabilities.
func setCapsAndCallSelf(conf *boot.Config, spec *specs.Spec) {
// Keep thread locked while capabilities are changed.
runtime.LockOSThread()
defer runtime.UnlockOSThread()
if err := boot.ApplyCaps(conf, spec.Process.Capabilities); err != nil {
Fatalf("ApplyCaps, err: %v", err)
}
binPath, err := specutils.BinPath()
if err != nil {
Fatalf("%v", err)
}
// Remove --apply-caps arg to call myself.
var args []string
for _, arg := range os.Args {
if !strings.Contains(arg, "apply-caps") {
args = append(args, arg)
}
}
log.Infof("Execve 'boot' again, bye!")
log.Infof("%s %v", binPath, args)
syscall.Exec(binPath, args, []string{})
}
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