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// Copyright 2018 Google LLC
//
// 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 (
"context"
"os"
"runtime/debug"
"strings"
"syscall"
"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 directory containing the OCI spec.
bundleDir string
// specFD is the file descriptor that the spec will be read from.
specFD int
// controllerFD is the file descriptor of a stream socket for the
// control server that is donated to this process.
controllerFD int
// deviceFD is the file descriptor for the platform device file.
deviceFD int
// ioFDs is the list of FDs used to connect to FS gofers.
ioFDs intFlags
// stdioFDs are the fds for stdin, stdout, and stderr. They must be
// provided in that order.
stdioFDs 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
// cpuNum number of CPUs to create inside the sandbox.
cpuNum int
// totalMem sets the initial amount of total memory to report back to the
// container.
totalMem uint64
// userLogFD is the file descriptor to write user logs to.
userLogFD int
// startSyncFD is the file descriptor to synchronize runsc and sandbox.
startSyncFD int
}
// 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] <container id>`
}
// 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.specFD, "spec-fd", -1, "required fd with the container spec")
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.IntVar(&b.deviceFD, "device-fd", -1, "FD for the platform device file")
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.Var(&b.stdioFDs, "stdio-fds", "list of FDs containing sandbox stdin, stdout, and stderr in that order")
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")
f.IntVar(&b.cpuNum, "cpu-num", 0, "number of CPUs to create inside the sandbox")
f.Uint64Var(&b.totalMem, "total-memory", 0, "sets the initial amount of total memory to report back to the container")
f.IntVar(&b.userLogFD, "user-log-fd", 0, "file descriptor to write user logs to. 0 means no logging.")
f.IntVar(&b.startSyncFD, "start-sync-fd", -1, "required FD to used to synchronize sandbox startup")
}
// 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.specFD == -1 || b.controllerFD == -1 || b.startSyncFD == -1 || f.NArg() != 1 {
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 specFD.
specFile := os.NewFile(uintptr(b.specFD), "spec file")
defer specFile.Close()
spec, err := specutils.ReadSpecFromFile(b.bundleDir, specFile)
if err != nil {
Fatalf("error reading spec: %v", err)
}
specutils.LogSpec(spec)
conf := args[0].(*boot.Config)
waitStatus := args[1].(*syscall.WaitStatus)
if b.applyCaps {
caps := spec.Process.Capabilities
if caps == nil {
caps = &specs.LinuxCapabilities{}
}
if conf.Platform == boot.PlatformPtrace {
// Ptrace platform requires extra capabilities.
const c = "CAP_SYS_PTRACE"
caps.Bounding = append(caps.Bounding, c)
caps.Effective = append(caps.Effective, c)
caps.Permitted = append(caps.Permitted, c)
}
// 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)
}
}
// Note that we've already read the spec from the spec FD, and
// we will read it again after the exec call. This works
// because the ReadSpecFromFile function seeks to the beginning
// of the file before reading.
if err := setCapsAndCallSelf(args, caps); err != nil {
Fatalf("%v", err)
}
panic("setCapsAndCallSelf must never return success")
}
// Create the loader.
bootArgs := boot.Args{
ID: f.Arg(0),
Spec: spec,
Conf: conf,
ControllerFD: b.controllerFD,
DeviceFD: b.deviceFD,
GoferFDs: b.ioFDs.GetArray(),
StdioFDs: b.stdioFDs.GetArray(),
Console: b.console,
NumCPU: b.cpuNum,
TotalMem: b.totalMem,
UserLogFD: b.userLogFD,
}
l, err := boot.New(bootArgs)
if err != nil {
Fatalf("error creating loader: %v", err)
}
// Fatalf exits the process and doesn't run defers.
// 'l' must be destroyed explicitly after this point!
// Notify the parent process the sandbox has booted (and that the controller
// is up).
startSyncFile := os.NewFile(uintptr(b.startSyncFD), "start-sync file")
buf := make([]byte, 1)
if w, err := startSyncFile.Write(buf); err != nil || w != 1 {
l.Destroy()
Fatalf("Unable to write into the start-sync descriptor: %v", err)
}
// Closes startSyncFile because 'l.Run()' only returns when the sandbox exits.
startSyncFile.Close()
// Wait for the start signal from runsc.
l.WaitForStartSignal()
// Run the application and wait for it to finish.
if err := l.Run(); err != nil {
l.Destroy()
Fatalf("error running sandbox: %v", err)
}
ws := l.WaitExit()
log.Infof("application exiting with %+v", ws)
*waitStatus = syscall.WaitStatus(ws.Status())
l.Destroy()
return subcommands.ExitSuccess
}
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