From 46ec7b5a94d370c4963ca361e9d96cb78d75d118 Mon Sep 17 00:00:00 2001

From: Kir Kolyshkin <kolyshkin@gmail.com>

Date: Tue, 23 Feb 2021 18:14:37 -0800

Subject: [PATCH 2/5] libct/rootfs: introduce and use mountConfig

The code is already passing three parameters around from

mountToRootfs to mountCgroupV* to mountToRootfs again.

I am about to add another parameter, so let's introduce and

use struct mountConfig to pass around.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

---

 libcontainer/rootfs_linux.go | 42 ++++++++++++++++++++++--------------

 1 file changed, 26 insertions(+), 16 deletions(-)

diff --git a/libcontainer/rootfs_linux.go b/libcontainer/rootfs_linux.go

index 411496ab7c6d..a384abb7e8a5 100644

--- a/libcontainer/rootfs_linux.go

+++ b/libcontainer/rootfs_linux.go

@@ -29,6 +29,12 @@ import (

 const defaultMountFlags = unix.MS_NOEXEC | unix.MS_NOSUID | unix.MS_NODEV

+type mountConfig struct {

+	root     string

+	label    string

+	cgroupns bool

+}

+

 // needsSetupDev returns true if /dev needs to be set up.

 func needsSetupDev(config *configs.Config) bool {

 	for _, m := range config.Mounts {

@@ -48,7 +54,11 @@ func prepareRootfs(pipe io.ReadWriter, iConfig *initConfig) (err error) {

 		return newSystemErrorWithCause(err, "preparing rootfs")

 	}

-	hasCgroupns := config.Namespaces.Contains(configs.NEWCGROUP)

+	mountConfig := &mountConfig{

+		root:     config.Rootfs,

+		label:    config.MountLabel,

+		cgroupns: config.Namespaces.Contains(configs.NEWCGROUP),

+	}

 	setupDev := needsSetupDev(config)

 	for _, m := range config.Mounts {

 		for _, precmd := range m.PremountCmds {

@@ -56,7 +66,7 @@ func prepareRootfs(pipe io.ReadWriter, iConfig *initConfig) (err error) {

 				return newSystemErrorWithCause(err, "running premount command")

 			}

 		}

-		if err := mountToRootfs(m, config.Rootfs, config.MountLabel, hasCgroupns); err != nil {

+		if err := mountToRootfs(m, mountConfig); err != nil {

 			return newSystemErrorWithCausef(err, "mounting %q to rootfs at %q", m.Source, m.Destination)

 		}

@@ -222,7 +232,7 @@ func prepareBindMount(m *configs.Mount, rootfs string) error {

 	return nil

 }

-func mountCgroupV1(m *configs.Mount, rootfs, mountLabel string, enableCgroupns bool) error {

+func mountCgroupV1(m *configs.Mount, c *mountConfig) error {

 	binds, err := getCgroupMounts(m)

 	if err != nil {

 		return err

@@ -242,12 +252,12 @@ func mountCgroupV1(m *configs.Mount, rootfs, mountLabel string, enableCgroupns b

 		Data:             "mode=755",

 		PropagationFlags: m.PropagationFlags,

 	}

-	if err := mountToRootfs(tmpfs, rootfs, mountLabel, enableCgroupns); err != nil {

+	if err := mountToRootfs(tmpfs, c); err != nil {

 		return err

 	}

 	for _, b := range binds {

-		if enableCgroupns {

-			subsystemPath := filepath.Join(rootfs, b.Destination)

+		if c.cgroupns {

+			subsystemPath := filepath.Join(c.root, b.Destination)

 			if err := os.MkdirAll(subsystemPath, 0755); err != nil {

 				return err

 			}

@@ -266,7 +276,7 @@ func mountCgroupV1(m *configs.Mount, rootfs, mountLabel string, enableCgroupns b

 				return err

 			}

 		} else {

-			if err := mountToRootfs(b, rootfs, mountLabel, enableCgroupns); err != nil {

+			if err := mountToRootfs(b, c); err != nil {

 				return err

 			}

 		}

@@ -276,7 +286,7 @@ func mountCgroupV1(m *configs.Mount, rootfs, mountLabel string, enableCgroupns b

 			// symlink(2) is very dumb, it will just shove the path into

 			// the link and doesn't do any checks or relative path

 			// conversion. Also, don't error out if the cgroup already exists.

-			if err := os.Symlink(mc, filepath.Join(rootfs, m.Destination, ss)); err != nil && !os.IsExist(err) {

+			if err := os.Symlink(mc, filepath.Join(c.root, m.Destination, ss)); err != nil && !os.IsExist(err) {

 				return err

 			}

 		}

@@ -284,8 +294,8 @@ func mountCgroupV1(m *configs.Mount, rootfs, mountLabel string, enableCgroupns b

 	return nil

 }

-func mountCgroupV2(m *configs.Mount, rootfs, mountLabel string, enableCgroupns bool) error {

-	cgroupPath, err := securejoin.SecureJoin(rootfs, m.Destination)

+func mountCgroupV2(m *configs.Mount, c *mountConfig) error {

+	cgroupPath, err := securejoin.SecureJoin(c.root, m.Destination)

 	if err != nil {

 		return err

 	}

@@ -302,10 +312,10 @@ func mountCgroupV2(m *configs.Mount, rootfs, mountLabel string, enableCgroupns b

 	return nil

 }

-func mountToRootfs(m *configs.Mount, rootfs, mountLabel string, enableCgroupns bool) error {

-	var (

-		dest = m.Destination

-	)

+func mountToRootfs(m *configs.Mount, c *mountConfig) error {

+	rootfs := c.root

+	mountLabel := c.label

+	dest := m.Destination

 	if !strings.HasPrefix(dest, rootfs) {

 		dest = filepath.Join(rootfs, dest)

 	}

@@ -424,9 +434,9 @@ func mountToRootfs(m *configs.Mount, rootfs, mountLabel string, enableCgroupns b

 		}

 	case "cgroup":

 		if cgroups.IsCgroup2UnifiedMode() {

-			return mountCgroupV2(m, rootfs, mountLabel, enableCgroupns)

+			return mountCgroupV2(m, c)

 		}

-		return mountCgroupV1(m, rootfs, mountLabel, enableCgroupns)

+		return mountCgroupV1(m, c)

 	default:

 		// ensure that the destination of the mount is resolved of symlinks at mount time because

 		// any previous mounts can invalidate the next mount's destination.

-- 

2.31.1