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moby--moby/pkg/chrootarchive/archive_unix.go

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// +build !windows
package chrootarchive
import (
"bytes"
"encoding/json"
"flag"
"fmt"
"io"
fix a race crash when building with "ADD some-broken.tar.xz ..." The race is between pools.Put which calls buf.Reset and exec.Cmd doing io.Copy from the buffer; it caused a runtime crash, as described in #16924: ``` docker-daemon cat the-tarball.xz | xz -d -c -q | docker-untar /path/to/... (aufs ) ``` When docker-untar side fails (like try to set xattr on aufs, or a broken tar), invokeUnpack will be responsible to exhaust all input, otherwise `xz` will be write pending for ever. this change add a receive only channel to cmdStream, and will close it to notify it's now safe to close the input stream; in CmdStream the change to use Stdin / Stdout / Stderr keeps the code simple, os/exec.Cmd will spawn goroutines and call io.Copy automatically. the CmdStream is actually called in the same file only, change it lowercase to mark as private. [...] INFO[0000] Docker daemon commit=0a8c2e3 execdriver=native-0.2 graphdriver=aufs version=1.8.2 DEBU[0006] Calling POST /build INFO[0006] POST /v1.20/build?cgroupparent=&cpuperiod=0&cpuquota=0&cpusetcpus=&cpusetmems=&cpushares=0&dockerfile=Dockerfile&memory=0&memswap=0&rm=1&t=gentoo-x32&ulimits=null DEBU[0008] [BUILDER] Cache miss DEBU[0009] Couldn't untar /home/lib-docker-v1.8.2-tmp/tmp/docker-build316710953/stage3-x32-20151004.tar.xz to /home/lib-docker-v1.8.2-tmp/aufs/mnt/d909abb87150463939c13e8a349b889a72d9b14f0cfcab42a8711979be285537: Untar re-exec error: exit status 1: output: operation not supported DEBU[0009] CopyFileWithTar(/home/lib-docker-v1.8.2-tmp/tmp/docker-build316710953/stage3-x32-20151004.tar.xz, /home/lib-docker-v1.8.2-tmp/aufs/mnt/d909abb87150463939c13e8a349b889a72d9b14f0cfcab42a8711979be285537/) panic: runtime error: slice bounds out of range goroutine 42 [running]: bufio.(*Reader).fill(0xc208187800) /usr/local/go/src/bufio/bufio.go:86 +0x2db bufio.(*Reader).WriteTo(0xc208187800, 0x7ff39602d150, 0xc2083f11a0, 0x508000, 0x0, 0x0) /usr/local/go/src/bufio/bufio.go:449 +0x27e io.Copy(0x7ff39602d150, 0xc2083f11a0, 0x7ff3960261f8, 0xc208187800, 0x0, 0x0, 0x0) /usr/local/go/src/io/io.go:354 +0xb2 github.com/docker/docker/pkg/archive.func·006() /go/src/github.com/docker/docker/pkg/archive/archive.go:817 +0x71 created by github.com/docker/docker/pkg/archive.CmdStream /go/src/github.com/docker/docker/pkg/archive/archive.go:819 +0x1ec goroutine 1 [chan receive]: main.(*DaemonCli).CmdDaemon(0xc20809da30, 0xc20800a020, 0xd, 0xd, 0x0, 0x0) /go/src/github.com/docker/docker/docker/daemon.go:289 +0x1781 reflect.callMethod(0xc208140090, 0xc20828fce0) /usr/local/go/src/reflect/value.go:605 +0x179 reflect.methodValueCall(0xc20800a020, 0xd, 0xd, 0x1, 0xc208140090, 0x0, 0x0, 0xc208140090, 0x0, 0x45343f, ...) /usr/local/go/src/reflect/asm_amd64.s:29 +0x36 github.com/docker/docker/cli.(*Cli).Run(0xc208129fb0, 0xc20800a010, 0xe, 0xe, 0x0, 0x0) /go/src/github.com/docker/docker/cli/cli.go:89 +0x38e main.main() /go/src/github.com/docker/docker/docker/docker.go:69 +0x428 goroutine 5 [syscall]: os/signal.loop() /usr/local/go/src/os/signal/signal_unix.go:21 +0x1f created by os/signal.init·1 /usr/local/go/src/os/signal/signal_unix.go:27 +0x35 Signed-off-by: Derek Ch <denc716@gmail.com>
2015-10-09 15:54:21 -04:00
"io/ioutil"
"os"
"runtime"
"github.com/docker/docker/pkg/archive"
"github.com/docker/docker/pkg/reexec"
)
// untar is the entry-point for docker-untar on re-exec. This is not used on
// Windows as it does not support chroot, hence no point sandboxing through
// chroot and rexec.
func untar() {
runtime.LockOSThread()
flag.Parse()
var options *archive.TarOptions
//read the options from the pipe "ExtraFiles"
if err := json.NewDecoder(os.NewFile(3, "options")).Decode(&options); err != nil {
fatal(err)
}
if err := chroot(flag.Arg(0)); err != nil {
fatal(err)
}
if err := archive.Unpack(os.Stdin, "/", options); err != nil {
fatal(err)
}
// fully consume stdin in case it is zero padded
if _, err := flush(os.Stdin); err != nil {
fatal(err)
}
os.Exit(0)
}
func invokeUnpack(decompressedArchive io.Reader, dest string, options *archive.TarOptions) error {
// We can't pass a potentially large exclude list directly via cmd line
// because we easily overrun the kernel's max argument/environment size
// when the full image list is passed (e.g. when this is used by
// `docker load`). We will marshall the options via a pipe to the
// child
r, w, err := os.Pipe()
if err != nil {
return fmt.Errorf("Untar pipe failure: %v", err)
}
cmd := reexec.Command("docker-untar", dest)
cmd.Stdin = decompressedArchive
cmd.ExtraFiles = append(cmd.ExtraFiles, r)
output := bytes.NewBuffer(nil)
cmd.Stdout = output
cmd.Stderr = output
if err := cmd.Start(); err != nil {
return fmt.Errorf("Untar error on re-exec cmd: %v", err)
}
//write the options to the pipe for the untar exec to read
if err := json.NewEncoder(w).Encode(options); err != nil {
return fmt.Errorf("Untar json encode to pipe failed: %v", err)
}
w.Close()
if err := cmd.Wait(); err != nil {
fix a race crash when building with "ADD some-broken.tar.xz ..." The race is between pools.Put which calls buf.Reset and exec.Cmd doing io.Copy from the buffer; it caused a runtime crash, as described in #16924: ``` docker-daemon cat the-tarball.xz | xz -d -c -q | docker-untar /path/to/... (aufs ) ``` When docker-untar side fails (like try to set xattr on aufs, or a broken tar), invokeUnpack will be responsible to exhaust all input, otherwise `xz` will be write pending for ever. this change add a receive only channel to cmdStream, and will close it to notify it's now safe to close the input stream; in CmdStream the change to use Stdin / Stdout / Stderr keeps the code simple, os/exec.Cmd will spawn goroutines and call io.Copy automatically. the CmdStream is actually called in the same file only, change it lowercase to mark as private. [...] INFO[0000] Docker daemon commit=0a8c2e3 execdriver=native-0.2 graphdriver=aufs version=1.8.2 DEBU[0006] Calling POST /build INFO[0006] POST /v1.20/build?cgroupparent=&cpuperiod=0&cpuquota=0&cpusetcpus=&cpusetmems=&cpushares=0&dockerfile=Dockerfile&memory=0&memswap=0&rm=1&t=gentoo-x32&ulimits=null DEBU[0008] [BUILDER] Cache miss DEBU[0009] Couldn't untar /home/lib-docker-v1.8.2-tmp/tmp/docker-build316710953/stage3-x32-20151004.tar.xz to /home/lib-docker-v1.8.2-tmp/aufs/mnt/d909abb87150463939c13e8a349b889a72d9b14f0cfcab42a8711979be285537: Untar re-exec error: exit status 1: output: operation not supported DEBU[0009] CopyFileWithTar(/home/lib-docker-v1.8.2-tmp/tmp/docker-build316710953/stage3-x32-20151004.tar.xz, /home/lib-docker-v1.8.2-tmp/aufs/mnt/d909abb87150463939c13e8a349b889a72d9b14f0cfcab42a8711979be285537/) panic: runtime error: slice bounds out of range goroutine 42 [running]: bufio.(*Reader).fill(0xc208187800) /usr/local/go/src/bufio/bufio.go:86 +0x2db bufio.(*Reader).WriteTo(0xc208187800, 0x7ff39602d150, 0xc2083f11a0, 0x508000, 0x0, 0x0) /usr/local/go/src/bufio/bufio.go:449 +0x27e io.Copy(0x7ff39602d150, 0xc2083f11a0, 0x7ff3960261f8, 0xc208187800, 0x0, 0x0, 0x0) /usr/local/go/src/io/io.go:354 +0xb2 github.com/docker/docker/pkg/archive.func·006() /go/src/github.com/docker/docker/pkg/archive/archive.go:817 +0x71 created by github.com/docker/docker/pkg/archive.CmdStream /go/src/github.com/docker/docker/pkg/archive/archive.go:819 +0x1ec goroutine 1 [chan receive]: main.(*DaemonCli).CmdDaemon(0xc20809da30, 0xc20800a020, 0xd, 0xd, 0x0, 0x0) /go/src/github.com/docker/docker/docker/daemon.go:289 +0x1781 reflect.callMethod(0xc208140090, 0xc20828fce0) /usr/local/go/src/reflect/value.go:605 +0x179 reflect.methodValueCall(0xc20800a020, 0xd, 0xd, 0x1, 0xc208140090, 0x0, 0x0, 0xc208140090, 0x0, 0x45343f, ...) /usr/local/go/src/reflect/asm_amd64.s:29 +0x36 github.com/docker/docker/cli.(*Cli).Run(0xc208129fb0, 0xc20800a010, 0xe, 0xe, 0x0, 0x0) /go/src/github.com/docker/docker/cli/cli.go:89 +0x38e main.main() /go/src/github.com/docker/docker/docker/docker.go:69 +0x428 goroutine 5 [syscall]: os/signal.loop() /usr/local/go/src/os/signal/signal_unix.go:21 +0x1f created by os/signal.init·1 /usr/local/go/src/os/signal/signal_unix.go:27 +0x35 Signed-off-by: Derek Ch <denc716@gmail.com>
2015-10-09 15:54:21 -04:00
// when `xz -d -c -q | docker-untar ...` failed on docker-untar side,
// we need to exhaust `xz`'s output, otherwise the `xz` side will be
// pending on write pipe forever
io.Copy(ioutil.Discard, decompressedArchive)
return fmt.Errorf("Error processing tar file(%v): %s", err, output)
}
return nil
}