Merge release-20190806.1-281-g9fb5622 (automated)

6 files changed, 66 insertions, 17 deletions

diff --git a/runsc/boot/config.go b/runsc/boot/config.go
index 38278d0a2..01a29e8d5 100644
--- a/runsc/boot/config.go
+++ b/runsc/boot/config.go
@@ -231,6 +231,10 @@ type Config struct {
 	// ReferenceLeakMode sets reference leak check mode
 	ReferenceLeakMode refs.LeakMode
 
+	// OverlayfsStaleRead causes cached FDs to reopen after a file is opened for
+	// write to workaround overlayfs limitation on kernels before 4.19.
+	OverlayfsStaleRead bool
+
 	// TestOnlyAllowRunAsCurrentUserWithoutChroot should only be used in
 	// tests. It allows runsc to start the sandbox process as the current
 	// user, and without chrooting the sandbox process. This can be
@@ -271,6 +275,7 @@ func (c *Config) ToFlags() []string {
 		"--rootless=" + strconv.FormatBool(c.Rootless),
 		"--alsologtostderr=" + strconv.FormatBool(c.AlsoLogToStderr),
 		"--ref-leak-mode=" + refsLeakModeToString(c.ReferenceLeakMode),
+		"--overlayfs-stale-read=" + strconv.FormatBool(c.OverlayfsStaleRead),
 	}
 	// Only include these if set since it is never to be used by users.
 	if c.TestOnlyAllowRunAsCurrentUserWithoutChroot {
diff --git a/runsc/boot/controller.go b/runsc/boot/controller.go
index a73c593ea..5f644b57e 100644
--- a/runsc/boot/controller.go
+++ b/runsc/boot/controller.go
@@ -32,6 +32,7 @@ import (
 	"gvisor.dev/gvisor/pkg/sentry/watchdog"
 	"gvisor.dev/gvisor/pkg/tcpip/stack"
 	"gvisor.dev/gvisor/pkg/urpc"
+	"gvisor.dev/gvisor/runsc/specutils"
 )
 
 const (
@@ -237,6 +238,9 @@ func (cm *containerManager) Start(args *StartArgs, _ *struct{}) error {
 		return fmt.Errorf("start arguments must contain stdin, stderr, and stdout followed by at least one file for the container root gofer")
 	}
 
+	// All validation passed, logs the spec for debugging.
+	specutils.LogSpec(args.Spec)
+
 	err := cm.l.startContainer(args.Spec, args.Conf, args.CID, args.FilePayload.Files)
 	if err != nil {
 		log.Debugf("containerManager.Start failed %q: %+v: %v", args.CID, args, err)
diff --git a/runsc/boot/filter/config.go b/runsc/boot/filter/config.go
index a2ecc6bcb..efbf1fd4a 100644
--- a/runsc/boot/filter/config.go
+++ b/runsc/boot/filter/config.go
@@ -44,6 +44,7 @@ var allowedSyscalls = seccomp.SyscallRules{
 	},
 	syscall.SYS_CLOSE:         {},
 	syscall.SYS_DUP:           {},
+	syscall.SYS_DUP2:          {},
 	syscall.SYS_EPOLL_CREATE1: {},
 	syscall.SYS_EPOLL_CTL:     {},
 	syscall.SYS_EPOLL_PWAIT: []seccomp.Rule{
diff --git a/runsc/boot/fs.go b/runsc/boot/fs.go
index 393c2a88b..76036c147 100644
--- a/runsc/boot/fs.go
+++ b/runsc/boot/fs.go
@@ -703,6 +703,14 @@ func (c *containerMounter) createRootMount(ctx context.Context, conf *Config) (*
 	log.Infof("Mounting root over 9P, ioFD: %d", fd)
 	p9FS := mustFindFilesystem("9p")
 	opts := p9MountOptions(fd, conf.FileAccess)
+
+	if conf.OverlayfsStaleRead {
+		// We can't check for overlayfs here because sandbox is chroot'ed and gofer
+		// can only send mount options for specs.Mounts (specs.Root is missing
+		// Options field). So assume root is always on top of overlayfs.
+		opts = append(opts, "overlayfs_stale_read")
+	}
+
 	rootInode, err := p9FS.Mount(ctx, rootDevice, mf, strings.Join(opts, ","), nil)
 	if err != nil {
 		return nil, fmt.Errorf("creating root mount point: %v", err)
@@ -737,7 +745,6 @@ func (c *containerMounter) getMountNameAndOptions(conf *Config, m specs.Mount) (
 		fsName     string
 		opts       []string
 		useOverlay bool
-		err        error
 	)
 
 	switch m.Type {
@@ -747,7 +754,12 @@ func (c *containerMounter) getMountNameAndOptions(conf *Config, m specs.Mount) (
 		fsName = sysfs
 	case tmpfs:
 		fsName = m.Type
+
+		var err error
 		opts, err = parseAndFilterOptions(m.Options, tmpfsAllowedOptions...)
+		if err != nil {
+			return "", nil, false, err
+		}
 
 	case bind:
 		fd := c.fds.remove()
@@ -763,7 +775,7 @@ func (c *containerMounter) getMountNameAndOptions(conf *Config, m specs.Mount) (
 		// for now.
 		log.Warningf("ignoring unknown filesystem type %q", m.Type)
 	}
-	return fsName, opts, useOverlay, err
+	return fsName, opts, useOverlay, nil
 }
 
 // mountSubmount mounts volumes inside the container's root. Because mounts may
diff --git a/runsc/cmd/gofer.go b/runsc/cmd/gofer.go
index 4c2fb80bf..4831210c0 100644
--- a/runsc/cmd/gofer.go
+++ b/runsc/cmd/gofer.go
@@ -27,6 +27,7 @@ import (
 	"flag"
 	"github.com/google/subcommands"
 	specs "github.com/opencontainers/runtime-spec/specs-go"
+	"golang.org/x/sys/unix"
 	"gvisor.dev/gvisor/pkg/log"
 	"gvisor.dev/gvisor/pkg/p9"
 	"gvisor.dev/gvisor/pkg/unet"
@@ -135,7 +136,7 @@ func (g *Gofer) Execute(_ context.Context, f *flag.FlagSet, args ...interface{})
 	//
 	// Note that all mount points have been mounted in the proper location in
 	// setupRootFS().
-	cleanMounts, err := resolveMounts(spec.Mounts, root)
+	cleanMounts, err := resolveMounts(conf, spec.Mounts, root)
 	if err != nil {
 		Fatalf("Failure to resolve mounts: %v", err)
 	}
@@ -380,7 +381,7 @@ func setupMounts(mounts []specs.Mount, root string) error {
 // Otherwise, it may follow symlinks to locations that would be overwritten
 // with another mount point and return the wrong location. In short, make sure
 // setupMounts() has been called before.
-func resolveMounts(mounts []specs.Mount, root string) ([]specs.Mount, error) {
+func resolveMounts(conf *boot.Config, mounts []specs.Mount, root string) ([]specs.Mount, error) {
 	cleanMounts := make([]specs.Mount, 0, len(mounts))
 	for _, m := range mounts {
 		if m.Type != "bind" || !specutils.IsSupportedDevMount(m) {
@@ -395,8 +396,15 @@ func resolveMounts(mounts []specs.Mount, root string) ([]specs.Mount, error) {
 		if err != nil {
 			panic(fmt.Sprintf("%q could not be made relative to %q: %v", dst, root, err))
 		}
+
+		opts, err := adjustMountOptions(conf, filepath.Join(root, relDst), m.Options)
+		if err != nil {
+			return nil, err
+		}
+
 		cpy := m
 		cpy.Destination = filepath.Join("/", relDst)
+		cpy.Options = opts
 		cleanMounts = append(cleanMounts, cpy)
 	}
 	return cleanMounts, nil
@@ -453,3 +461,20 @@ func resolveSymlinksImpl(root, base, rel string, followCount uint) (string, erro
 	}
 	return base, nil
 }
+
+// adjustMountOptions adds 'overlayfs_stale_read' if mounting over overlayfs.
+func adjustMountOptions(conf *boot.Config, path string, opts []string) ([]string, error) {
+	rv := make([]string, len(opts))
+	copy(rv, opts)
+
+	if conf.OverlayfsStaleRead {
+		statfs := syscall.Statfs_t{}
+		if err := syscall.Statfs(path, &statfs); err != nil {
+			return nil, err
+		}
+		if statfs.Type == unix.OVERLAYFS_SUPER_MAGIC {
+			rv = append(rv, "overlayfs_stale_read")
+		}
+	}
+	return rv, nil
+}
diff --git a/runsc/main.go b/runsc/main.go
index 7dce9dc00..80b2d300c 100644
--- a/runsc/main.go
+++ b/runsc/main.go
@@ -41,35 +41,36 @@ import (
 var (
 	// Although these flags are not part of the OCI spec, they are used by
 	// Docker, and thus should not be changed.
-	rootDir     = flag.String("root", "", "root directory for storage of container state")
-	logFilename = flag.String("log", "", "file path where internal debug information is written, default is stdout")
-	logFormat   = flag.String("log-format", "text", "log format: text (default), json, or json-k8s")
-	debug       = flag.Bool("debug", false, "enable debug logging")
-	showVersion = flag.Bool("version", false, "show version and exit")
+	rootDir     = flag.String("root", "", "root directory for storage of container state.")
+	logFilename = flag.String("log", "", "file path where internal debug information is written, default is stdout.")
+	logFormat   = flag.String("log-format", "text", "log format: text (default), json, or json-k8s.")
+	debug       = flag.Bool("debug", false, "enable debug logging.")
+	showVersion = flag.Bool("version", false, "show version and exit.")
 
 	// These flags are unique to runsc, and are used to configure parts of the
 	// system that are not covered by the runtime spec.
 
 	// Debugging flags.
 	debugLog        = flag.String("debug-log", "", "additional location for logs. If it ends with '/', log files are created inside the directory with default names. The following variables are available: %TIMESTAMP%, %COMMAND%.")
-	logPackets      = flag.Bool("log-packets", false, "enable network packet logging")
+	logPackets      = flag.Bool("log-packets", false, "enable network packet logging.")
 	logFD           = flag.Int("log-fd", -1, "file descriptor to log to.  If set, the 'log' flag is ignored.")
 	debugLogFD      = flag.Int("debug-log-fd", -1, "file descriptor to write debug logs to.  If set, the 'debug-log-dir' flag is ignored.")
-	debugLogFormat  = flag.String("debug-log-format", "text", "log format: text (default), json, or json-k8s")
-	alsoLogToStderr = flag.Bool("alsologtostderr", false, "send log messages to stderr")
+	debugLogFormat  = flag.String("debug-log-format", "text", "log format: text (default), json, or json-k8s.")
+	alsoLogToStderr = flag.Bool("alsologtostderr", false, "send log messages to stderr.")
 
 	// Debugging flags: strace related
-	strace         = flag.Bool("strace", false, "enable strace")
+	strace         = flag.Bool("strace", false, "enable strace.")
 	straceSyscalls = flag.String("strace-syscalls", "", "comma-separated list of syscalls to trace. If --strace is true and this list is empty, then all syscalls will be traced.")
-	straceLogSize  = flag.Uint("strace-log-size", 1024, "default size (in bytes) to log data argument blobs")
+	straceLogSize  = flag.Uint("strace-log-size", 1024, "default size (in bytes) to log data argument blobs.")
 
 	// Flags that control sandbox runtime behavior.
-	platformName       = flag.String("platform", "ptrace", "specifies which platform to use: ptrace (default), kvm")
+	platformName       = flag.String("platform", "ptrace", "specifies which platform to use: ptrace (default), kvm.")
 	network            = flag.String("network", "sandbox", "specifies which network to use: sandbox (default), host, none. Using network inside the sandbox is more secure because it's isolated from the host network.")
-	gso                = flag.Bool("gso", true, "enable generic segmenation offload")
+	gso                = flag.Bool("gso", true, "enable generic segmenation offload.")
 	fileAccess         = flag.String("file-access", "exclusive", "specifies which filesystem to use for the root mount: exclusive (default), shared. Volume mounts are always shared.")
-	fsGoferHostUDS     = flag.Bool("fsgofer-host-uds", false, "Allow the gofer to mount Unix Domain Sockets.")
+	fsGoferHostUDS     = flag.Bool("fsgofer-host-uds", false, "allow the gofer to mount Unix Domain Sockets.")
 	overlay            = flag.Bool("overlay", false, "wrap filesystem mounts with writable overlay. All modifications are stored in memory inside the sandbox.")
+	overlayfsStaleRead = flag.Bool("overlayfs-stale-read", false, "reopen cached FDs after a file is opened for write to workaround overlayfs limitation on kernels before 4.19.")
 	watchdogAction     = flag.String("watchdog-action", "log", "sets what action the watchdog takes when triggered: log (default), panic.")
 	panicSignal        = flag.Int("panic-signal", -1, "register signal handling that panics. Usually set to SIGUSR2(12) to troubleshoot hangs. -1 disables it.")
 	profile            = flag.Bool("profile", false, "prepares the sandbox to use Golang profiler. Note that enabling profiler loosens the seccomp protection added to the sandbox (DO NOT USE IN PRODUCTION).")
@@ -212,6 +213,7 @@ func main() {
 		Rootless:           *rootless,
 		AlsoLogToStderr:    *alsoLogToStderr,
 		ReferenceLeakMode:  refsLeakMode,
+		OverlayfsStaleRead: *overlayfsStaleRead,
 
 		TestOnlyAllowRunAsCurrentUserWithoutChroot: *testOnlyAllowRunAsCurrentUserWithoutChroot,
 		TestOnlyTestNameEnv:                        *testOnlyTestNameEnv,