Add support for --chrootdirs

Signed-off-by: LStandman <65296484+LStandman@users.noreply.github.com>

13 files changed, 116 insertions, 4 deletions

diff --git a/cmd/podman/common/create.go b/cmd/podman/common/create.go
index 634b49db7..f3e2e4d6d 100644
--- a/cmd/podman/common/create.go
+++ b/cmd/podman/common/create.go
@@ -631,6 +631,14 @@ func DefineCreateFlags(cmd *cobra.Command, cf *entities.ContainerCreateOptions,
 			"Write the container process ID to the file")
 		_ = cmd.RegisterFlagCompletionFunc(pidFileFlagName, completion.AutocompleteDefault)
 
+		chrootDirsFlagName := "chrootdirs"
+		createFlags.StringSliceVar(
+			&cf.ChrootDirs,
+			chrootDirsFlagName, []string{},
+			"Chroot directories inside the container",
+		)
+		_ = cmd.RegisterFlagCompletionFunc(chrootDirsFlagName, completion.AutocompleteDefault)
+
 		if registry.IsRemote() {
 			_ = createFlags.MarkHidden("env-host")
 			_ = createFlags.MarkHidden("http-proxy")
diff --git a/docs/source/markdown/podman-create.1.md b/docs/source/markdown/podman-create.1.md
index 2a0f3b738..506f575fe 100644
--- a/docs/source/markdown/podman-create.1.md
+++ b/docs/source/markdown/podman-create.1.md
@@ -1453,6 +1453,11 @@ After the container is started, the location for the pidfile can be discovered w
     $ podman inspect --format '{{ .PidFile }}' $CID
     /run/containers/storage/${storage-driver}-containers/$CID/userdata/pidfile
 
+#### **--chrootdirs**=*path*
+
+Path to a directory inside the container that should be treated as a `chroot` directory.
+Any Podman managed file (e.g., /etc/resolv.conf, /etc/hosts, etc/hostname) that is mounted into the root directory will be mounted into that location as well.
+Multiple directories should be separated with a comma.
 
 ## EXAMPLES
 
diff --git a/docs/source/markdown/podman-run.1.md b/docs/source/markdown/podman-run.1.md
index 239cf3b83..7fa7bda30 100644
--- a/docs/source/markdown/podman-run.1.md
+++ b/docs/source/markdown/podman-run.1.md
@@ -1529,6 +1529,12 @@ After the container is started, the location for the pidfile can be discovered w
     $ podman inspect --format '{{ .PidFile }}' $CID
     /run/containers/storage/${storage-driver}-containers/$CID/userdata/pidfile
 
+#### **--chrootdirs**=*path*
+
+Path to a directory inside the container that should be treated as a `chroot` directory.
+Any Podman managed file (e.g., /etc/resolv.conf, /etc/hosts, etc/hostname) that is mounted into the root directory will be mounted into that location as well.
+Multiple directories should be separated with a comma.
+
 ## Exit Status
 
 The exit code from **podman run** gives information about why the container
diff --git a/libpod/container_config.go b/libpod/container_config.go
index e56f1342a..0d9cd5723 100644
--- a/libpod/container_config.go
+++ b/libpod/container_config.go
@@ -165,6 +165,10 @@ type ContainerRootFSConfig struct {
 	Volatile bool `json:"volatile,omitempty"`
 	// Passwd allows to user to override podman's passwd/group file setup
 	Passwd *bool `json:"passwd,omitempty"`
+	// ChrootDirs is an additional set of directories that need to be
+	// treated as root directories. Standard bind mounts will be mounted
+	// into paths relative to these directories.
+	ChrootDirs []string `json:"chroot_directories,omitempty"`
 }
 
 // ContainerSecurityConfig is an embedded sub-config providing security configuration
diff --git a/libpod/container_inspect.go b/libpod/container_inspect.go
index 3df6203e3..5fb32bd90 100644
--- a/libpod/container_inspect.go
+++ b/libpod/container_inspect.go
@@ -411,6 +411,7 @@ func (c *Container) generateInspectContainerConfig(spec *spec.Spec) *define.Insp
 	}
 
 	ctrConfig.Passwd = c.config.Passwd
+	ctrConfig.ChrootDirs = append(ctrConfig.ChrootDirs, c.config.ChrootDirs...)
 
 	return ctrConfig
 }
diff --git a/libpod/container_internal_linux.go b/libpod/container_internal_linux.go
index 1517a7df7..75250b9b1 100644
--- a/libpod/container_internal_linux.go
+++ b/libpod/container_internal_linux.go
@@ -1811,6 +1811,17 @@ func (c *Container) getRootNetNsDepCtr() (depCtr *Container, err error) {
 	return depCtr, nil
 }
 
+// Ensure standard bind mounts are mounted into all root directories (including chroot directories)
+func (c *Container) mountIntoRootDirs(mountName string, mountPath string) error {
+	c.state.BindMounts[mountName] = mountPath
+
+	for _, chrootDir := range c.config.ChrootDirs {
+		c.state.BindMounts[filepath.Join(chrootDir, mountName)] = mountPath
+	}
+
+	return nil
+}
+
 // Make standard bind mounts to include in the container
 func (c *Container) makeBindMounts() error {
 	if err := os.Chown(c.state.RunDir, c.RootUID(), c.RootGID()); err != nil {
@@ -1864,7 +1875,11 @@ func (c *Container) makeBindMounts() error {
 			// If it doesn't, don't copy them
 			resolvPath, exists := bindMounts["/etc/resolv.conf"]
 			if !c.config.UseImageResolvConf && exists {
-				c.state.BindMounts["/etc/resolv.conf"] = resolvPath
+				err := c.mountIntoRootDirs("/etc/resolv.conf", resolvPath)
+
+				if err != nil {
+					return errors.Wrapf(err, "error assigning mounts to container %s", c.ID())
+				}
 			}
 
 			// check if dependency container has an /etc/hosts file.
@@ -1884,7 +1899,11 @@ func (c *Container) makeBindMounts() error {
 				depCtr.lock.Unlock()
 
 				// finally, save it in the new container
-				c.state.BindMounts["/etc/hosts"] = hostsPath
+				err := c.mountIntoRootDirs("/etc/hosts", hostsPath)
+
+				if err != nil {
+					return errors.Wrapf(err, "error assigning mounts to container %s", c.ID())
+				}
 			}
 
 			if !hasCurrentUserMapped(c) {
@@ -1901,7 +1920,11 @@ func (c *Container) makeBindMounts() error {
 				if err != nil {
 					return errors.Wrapf(err, "error creating resolv.conf for container %s", c.ID())
 				}
-				c.state.BindMounts["/etc/resolv.conf"] = newResolv
+				err = c.mountIntoRootDirs("/etc/resolv.conf", newResolv)
+
+				if err != nil {
+					return errors.Wrapf(err, "error assigning mounts to container %s", c.ID())
+				}
 			}
 
 			if !c.config.UseImageHosts {
@@ -2329,7 +2352,11 @@ func (c *Container) updateHosts(path string) error {
 	if err != nil {
 		return err
 	}
-	c.state.BindMounts["/etc/hosts"] = newHosts
+
+	if err = c.mountIntoRootDirs("/etc/hosts", newHosts); err != nil {
+		return err
+	}
+
 	return nil
 }
 
diff --git a/libpod/define/container_inspect.go b/libpod/define/container_inspect.go
index 804b2b143..ae2ce9724 100644
--- a/libpod/define/container_inspect.go
+++ b/libpod/define/container_inspect.go
@@ -75,6 +75,10 @@ type InspectContainerConfig struct {
 	StopTimeout uint `json:"StopTimeout"`
 	// Passwd determines whether or not podman can add entries to /etc/passwd and /etc/group
 	Passwd *bool `json:"Passwd,omitempty"`
+	// ChrootDirs is an additional set of directories that need to be
+	// treated as root directories. Standard bind mounts will be mounted
+	// into paths relative to these directories.
+	ChrootDirs []string `json:"ChrootDirs,omitempty"`
 }
 
 // InspectRestartPolicy holds information about the container's restart policy.
diff --git a/libpod/options.go b/libpod/options.go
index 1ee4e7322..2e5454393 100644
--- a/libpod/options.go
+++ b/libpod/options.go
@@ -2036,3 +2036,18 @@ func WithVolatile() CtrCreateOption {
 		return nil
 	}
 }
+
+// WithChrootDirs is an additional set of directories that need to be
+// treated as root directories. Standard bind mounts will be mounted
+// into paths relative to these directories.
+func WithChrootDirs(dirs []string) CtrCreateOption {
+	return func(ctr *Container) error {
+		if ctr.valid {
+			return define.ErrCtrFinalized
+		}
+
+		ctr.config.ChrootDirs = dirs
+
+		return nil
+	}
+}
diff --git a/pkg/domain/entities/pods.go b/pkg/domain/entities/pods.go
index 6fb3db1b5..da93d3f8b 100644
--- a/pkg/domain/entities/pods.go
+++ b/pkg/domain/entities/pods.go
@@ -263,6 +263,7 @@ type ContainerCreateOptions struct {
 	Workdir           string
 	SeccompPolicy     string
 	PidFile           string
+	ChrootDirs        []string
 	IsInfra           bool
 	IsClone           bool
 
diff --git a/pkg/specgen/generate/container_create.go b/pkg/specgen/generate/container_create.go
index c0b23953f..8ab0eae5a 100644
--- a/pkg/specgen/generate/container_create.go
+++ b/pkg/specgen/generate/container_create.go
@@ -526,6 +526,10 @@ func createContainerOptions(ctx context.Context, rt *libpod.Runtime, s *specgen.
 		options = append(options, libpod.WithPidFile(s.PidFile))
 	}
 
+	if len(s.ChrootDirs) != 0 {
+		options = append(options, libpod.WithChrootDirs(s.ChrootDirs))
+	}
+
 	options = append(options, libpod.WithSelectedPasswordManagement(s.Passwd))
 
 	return options, nil
diff --git a/pkg/specgen/specgen.go b/pkg/specgen/specgen.go
index 7f6f79b87..27d77af9f 100644
--- a/pkg/specgen/specgen.go
+++ b/pkg/specgen/specgen.go
@@ -301,6 +301,10 @@ type ContainerStorageConfig struct {
 	// Volatile specifies whether the container storage can be optimized
 	// at the cost of not syncing all the dirty files in memory.
 	Volatile bool `json:"volatile,omitempty"`
+	// ChrootDirs is an additional set of directories that need to be
+	// treated as root directories. Standard bind mounts will be mounted
+	// into paths relative to these directories.
+	ChrootDirs []string `json:"chroot_directories,omitempty"`
 }
 
 // ContainerSecurityConfig is a container's security features, including
diff --git a/pkg/specgenutil/specgen.go b/pkg/specgenutil/specgen.go
index b037e14cc..b87da61fb 100644
--- a/pkg/specgenutil/specgen.go
+++ b/pkg/specgenutil/specgen.go
@@ -819,6 +819,9 @@ func FillOutSpecGen(s *specgen.SpecGenerator, c *entities.ContainerCreateOptions
 	if !s.UnsetEnvAll {
 		s.UnsetEnvAll = c.UnsetEnvAll
 	}
+	if len(s.ChrootDirs) == 0 || len(c.ChrootDirs) != 0 {
+		s.ChrootDirs = c.ChrootDirs
+	}
 
 	// Initcontainers
 	if len(s.InitContainerType) == 0 || len(c.InitContainerType) != 0 {
diff --git a/test/e2e/create_test.go b/test/e2e/create_test.go
index 6a4a394ef..339fa66d8 100644
--- a/test/e2e/create_test.go
+++ b/test/e2e/create_test.go
@@ -706,4 +706,34 @@ var _ = Describe("Podman create", func() {
 		Expect(create.ErrorToString()).To(ContainSubstring("cannot specify a new uid/gid map when entering a pod with an infra container"))
 
 	})
+
+	It("podman create --chrootdirs inspection test", func() {
+		session := podmanTest.Podman([]string{"create", "--chrootdirs", "/var/local/qwerty", ALPINE})
+		session.WaitWithDefaultTimeout()
+		Expect(session).Should(Exit(0))
+
+		setup := podmanTest.Podman([]string{"container", "inspect", session.OutputToString()})
+		setup.WaitWithDefaultTimeout()
+		Expect(setup).Should(Exit(0))
+
+		data := setup.InspectContainerToJSON()
+		Expect(data).To(HaveLen(1))
+		Expect(data[0].Config.ChrootDirs).To(HaveLen(1))
+		Expect(data[0].Config.ChrootDirs[0]).To(Equal("/var/local/qwerty"))
+	})
+
+	It("podman create --chrootdirs functionality test", func() {
+		session := podmanTest.Podman([]string{"create", "-t", "--chrootdirs", "/var/local/qwerty", ALPINE, "/bin/cat"})
+		session.WaitWithDefaultTimeout()
+		Expect(session).Should(Exit(0))
+		ctrID := session.OutputToString()
+
+		setup := podmanTest.Podman([]string{"start", ctrID})
+		setup.WaitWithDefaultTimeout()
+		Expect(setup).Should(Exit(0))
+
+		setup = podmanTest.Podman([]string{"exec", ctrID, "cmp", "/etc/resolv.conf", "/var/local/qwerty/etc/resolv.conf"})
+		setup.WaitWithDefaultTimeout()
+		Expect(setup).Should(Exit(0))
+	})
 })