executor: Share selinux (process and mount) label of first stage with other stages in same build

buildah.go

@@ -340,6 +340,10 @@ type BuilderOptions struct {
 	// OciDecryptConfig contains the config that can be used to decrypt an image if it is
 	// encrypted if non-nil. If nil, it does not attempt to decrypt an image.
 	OciDecryptConfig *encconfig.DecryptConfig
+	// ProcessLabel is the SELinux process label associated with the container
+	ProcessLabel string
+	// MountLabel is the SELinux mount label associated with the container
+	MountLabel string
 }
 
 // ImportOptions are used to initialize a Builder from an existing container

imagebuildah/executor.go

@@ -131,6 +131,8 @@ type Executor struct {
 	sshsources              map[string]*sshagent.Source
 	logPrefix               string
 	unsetEnvs               []string
+	processLabel            string // Shares processLabel of first stage container with containers of other stages in same build
+	mountLabel              string // Shares mountLabel of first stage container with containers of other stages in same build
 }
 
 type imageTypeAndHistoryAndDiffIDs struct {

imagebuildah/stage_executor.go

@@ -621,13 +621,25 @@ func (s *StageExecutor) prepare(ctx context.Context, from string, initializeIBCo
 		PullRetryDelay:        s.executor.retryPullPushDelay,
 		OciDecryptConfig:      s.executor.ociDecryptConfig,
 		Logger:                s.executor.logger,
+		ProcessLabel:          s.executor.processLabel,
+		MountLabel:            s.executor.mountLabel,
 	}
 
 	builder, err = buildah.NewBuilder(ctx, s.executor.store, builderOptions)
 	if err != nil {
 		return nil, errors.Wrapf(err, "error creating build container")
 	}
 
+	// If executor's ProcessLabel and MountLabel is empty means this is the first stage
+	// Make sure we share first stage's ProcessLabel and MountLabel with all other subsequent stages
+	// Doing this will ensure and one stage in same build can mount another stage even if `selinux`
+	// is enabled.
+
+	if s.executor.mountLabel == "" && s.executor.processLabel == "" {
+		s.executor.mountLabel = builder.MountLabel
+		s.executor.processLabel = builder.ProcessLabel
+	}
+
 	if initializeIBConfig {
 		volumes := map[string]struct{}{}
 		for _, v := range builder.Volumes() {

internal/parse/parse.go

@@ -15,7 +15,6 @@ import (
 	"github.com/containers/storage"
 	"github.com/containers/storage/pkg/idtools"
 	specs "github.com/opencontainers/runtime-spec/specs-go"
-	selinux "github.com/opencontainers/selinux/go-selinux"
 	"github.com/pkg/errors"
 )
 
@@ -113,8 +112,7 @@ func GetBindMount(ctx *types.SystemContext, args []string, contextDir string, st
 	isImageMounted := false
 	if fromImage != "" {
 		mountPoint := ""
-		//TODO: remove this selinux check when comment is resolved. https://github.com/containers/buildah/pull/3590#issuecomment-956349109
-		if additionalMountPoints != nil && (selinux.EnforceMode() != 1) {
+		if additionalMountPoints != nil {
 			if val, ok := additionalMountPoints[fromImage]; ok {
 				mountPoint = val.MountPoint
 			}
@@ -280,8 +278,7 @@ func GetCacheMount(args []string, store storage.Store, imageMountLabel string, a
 		// do not create cache on host
 		// instead use read-only mounted stage as cache
 		mountPoint := ""
-		//TODO: remove this selinux check when comment is resolved. https://github.com/containers/buildah/pull/3590#issuecomment-956349109
-		if additionalMountPoints != nil && (selinux.EnforceMode() != 1) {
+		if additionalMountPoints != nil {
 			if val, ok := additionalMountPoints[fromStage]; ok {
 				if val.IsStage {
 					mountPoint = val.MountPoint

new.go

@@ -230,9 +230,20 @@ func newBuilder(ctx context.Context, store storage.Store, options BuilderOptions
 
 	conflict := 100
 	for {
+
+		var flags map[string]interface{}
+		// check if we have predefined ProcessLabel and MountLabel
+		// this could be true if this is another stage in a build
+		if options.ProcessLabel != "" && options.MountLabel != "" {
+			flags = map[string]interface{}{
+				"ProcessLabel": options.ProcessLabel,
+				"MountLabel":   options.MountLabel,
+			}
+		}
 		coptions := storage.ContainerOptions{
 			LabelOpts:        options.CommonBuildOpts.LabelOpts,
 			IDMappingOptions: newContainerIDMappingOptions(options.IDMappingOptions),
+			Flags:            flags,
 			Volatile:         true,
 		}
 		container, err = store.CreateContainer("", []string{tmpName}, imageID, "", "", &coptions)

tests/bud.bats

@@ -3759,13 +3759,6 @@ _EOF
 }
 
 @test "bud-with-writeable-mount-bind-from-like-buildkit" {
-  if which selinuxenabled > /dev/null 2> /dev/null ; then
-	if selinuxenabled ; then
-                #TODO: Once pending commit from https://github.com/containers/buildah/pull/3590 is merged
-                #See comment: https://github.com/containers/buildah/pull/3590#issuecomment-956349109
-		skip "skip if selinux enabled, since stages have different selinux label"
-	fi
-  fi
   skip_if_no_runtime
   skip_if_in_container
   mkdir ${TESTDIR}/bud
@@ -3807,13 +3800,6 @@ _EOF
 }
 
 @test "bud-with-mount-cache-from-like-buildkit" {
-  if which selinuxenabled > /dev/null 2> /dev/null ; then
-	if selinuxenabled ; then
-                #TODO: Once pending commit from https://github.com/containers/buildah/pull/3590 is merged
-                #See comment: https://github.com/containers/buildah/pull/3590#issuecomment-956349109
-		skip "skip if selinux enabled, since stages have different selinux label"
-	fi
-  fi
   skip_if_no_runtime
   skip_if_in_container
   mkdir ${TESTDIR}/bud
@@ -3826,13 +3812,6 @@ _EOF
 
 # following test must fail
 @test "bud-with-mount-cache-image-from-like-buildkit" {
-  if which selinuxenabled > /dev/null 2> /dev/null ; then
-	if selinuxenabled ; then
-                #TODO: Once pending commit from https://github.com/containers/buildah/pull/3590 is merged
-                #See comment: https://github.com/containers/buildah/pull/3590#issuecomment-956349109
-		skip "skip if selinux enabled, since stages have different selinux label"
-	fi
-  fi
   skip_if_no_runtime
   skip_if_in_container
   mkdir ${TESTDIR}/bud
@@ -3846,13 +3825,6 @@ _EOF
 }
 
 @test "bud-with-mount-cache-multiple-from-like-buildkit" {
-  if which selinuxenabled > /dev/null 2> /dev/null ; then
-	if selinuxenabled ; then
-                #TODO: Once pending commit from https://github.com/containers/buildah/pull/3590 is merged
-                #See comment: https://github.com/containers/buildah/pull/3590#issuecomment-956349109
-		skip "skip if selinux enabled, since stages have different selinux label"
-	fi
-  fi
   skip_if_no_runtime
   skip_if_in_container
   mkdir ${TESTDIR}/bud
@@ -3879,14 +3851,6 @@ _EOF
 }
 
 @test "bud-with-mount-bind-from-multistage-relative-like-buildkit" {
-  if which selinuxenabled > /dev/null 2> /dev/null ; then
-	if selinuxenabled ; then
-                #TODO: Once pending commit from https://github.com/containers/buildah/pull/3590 is merged
-                #See comment: https://github.com/containers/buildah/pull/3590#issuecomment-956349109
-		skip "skip if selinux enabled, since stages have different selinux label"
-	fi
-  fi
-
   mkdir ${TESTDIR}/bud
   cp -R ${TESTSDIR}/bud/buildkit-mount-from ${TESTDIR}/bud/buildkit-mount-from
   skip_if_no_runtime
@@ -3898,14 +3862,6 @@ _EOF
 }
 
 @test "bud-with-mount-bind-from-cache-multistage-relative-like-buildkit" {
-  if which selinuxenabled > /dev/null 2> /dev/null ; then
-	if selinuxenabled ; then
-                #TODO: Once pending commit from https://github.com/containers/buildah/pull/3590 is merged
-                #See comment: https://github.com/containers/buildah/pull/3590#issuecomment-956349109
-		skip "skip if selinux enabled, since stages have different selinux label"
-	fi
-  fi
-
   skip_if_no_runtime
   skip_if_in_container
   mkdir ${TESTDIR}/bud