Merge pull request #965 from tonistiigi/bake-context-validation

bake: additional support for named context on remote inputs

bake/bake.go

@@ -7,6 +7,7 @@ import (
 	"io/ioutil"
 	"os"
 	"path"
+	"path/filepath"
 	"regexp"
 	"sort"
 	"strconv"
@@ -715,6 +716,21 @@ func updateContext(t *build.Inputs, inp *Input) {
 	if inp == nil || inp.State == nil {
 		return
 	}
+
+	for k, v := range t.NamedContexts {
+		if v.Path == "." {
+			t.NamedContexts[k] = build.NamedContext{Path: inp.URL}
+		}
+		if strings.HasPrefix(v.Path, "cwd://") || strings.HasPrefix(v.Path, "target:") || strings.HasPrefix(v.Path, "docker-image:") {
+			continue
+		}
+		if IsRemoteURL(v.Path) {
+			continue
+		}
+		st := llb.Scratch().File(llb.Copy(*inp.State, v.Path, "/"), llb.WithCustomNamef("set context %s to %s", k, v.Path))
+		t.NamedContexts[k] = build.NamedContext{State: &st}
+	}
+
 	if t.ContextPath == "." {
 		t.ContextPath = inp.URL
 		return
@@ -729,6 +745,59 @@ func updateContext(t *build.Inputs, inp *Input) {
 	t.ContextState = &st
 }
 
+// validateContextsEntitlements is a basic check to ensure contexts do not
+// escape local directories when loaded from remote sources. This is to be
+// replaced with proper entitlements support in the future.
+func validateContextsEntitlements(t build.Inputs, inp *Input) error {
+	if inp == nil || inp.State == nil {
+		return nil
+	}
+	if v, ok := os.LookupEnv("BAKE_ALLOW_REMOTE_FS_ACCESS"); ok {
+		if vv, _ := strconv.ParseBool(v); vv {
+			return nil
+		}
+	}
+	if t.ContextState == nil {
+		if err := checkPath(t.ContextPath); err != nil {
+			return err
+		}
+	}
+	for _, v := range t.NamedContexts {
+		if v.State != nil {
+			continue
+		}
+		if err := checkPath(v.Path); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func checkPath(p string) error {
+	if IsRemoteURL(p) || strings.HasPrefix(p, "target:") || strings.HasPrefix(p, "docker-image:") {
+		return nil
+	}
+	p, err := filepath.EvalSymlinks(p)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil
+		}
+		return err
+	}
+	wd, err := os.Getwd()
+	if err != nil {
+		return err
+	}
+	rel, err := filepath.Rel(wd, p)
+	if err != nil {
+		return err
+	}
+	if strings.HasPrefix(rel, ".."+string(os.PathSeparator)) {
+		return errors.Errorf("path %s is outside of the working directory, please set BAKE_ALLOW_REMOTE_FS_ACCESS=1", p)
+	}
+	return nil
+}
+
 func toBuildOpt(t *Target, inp *Input) (*build.Options, error) {
 	if v := t.Context; v != nil && *v == "-" {
 		return nil, errors.Errorf("context from stdin not allowed in bake")
@@ -769,7 +838,7 @@ func toBuildOpt(t *Target, inp *Input) (*build.Options, error) {
 	bi := build.Inputs{
 		ContextPath:    contextPath,
 		DockerfilePath: dockerfilePath,
-		NamedContexts:  t.Contexts,
+		NamedContexts:  toNamedContexts(t.Contexts),
 	}
 	if t.DockerfileInline != nil {
 		bi.DockerfileInline = *t.DockerfileInline
@@ -778,6 +847,15 @@ func toBuildOpt(t *Target, inp *Input) (*build.Options, error) {
 	if strings.HasPrefix(bi.ContextPath, "cwd://") {
 		bi.ContextPath = path.Clean(strings.TrimPrefix(bi.ContextPath, "cwd://"))
 	}
+	for k, v := range bi.NamedContexts {
+		if strings.HasPrefix(v.Path, "cwd://") {
+			bi.NamedContexts[k] = build.NamedContext{Path: path.Clean(strings.TrimPrefix(v.Path, "cwd://"))}
+		}
+	}
+
+	if err := validateContextsEntitlements(bi, inp); err != nil {
+		return nil, err
+	}
 
 	t.Context = &bi.ContextPath
 
@@ -903,3 +981,11 @@ func sliceEqual(s1, s2 []string) bool {
 	}
 	return true
 }
+
+func toNamedContexts(m map[string]string) map[string]build.NamedContext {
+	m2 := make(map[string]build.NamedContext, len(m))
+	for k, v := range m {
+		m2[k] = build.NamedContext{Path: v}
+	}
+	return m2
+}

bake/bake_test.go

@@ -386,8 +386,8 @@ func TestReadContexts(t *testing.T) {
 	ctxs := bo["app"].Inputs.NamedContexts
 	require.Equal(t, 2, len(ctxs))
 
-	require.Equal(t, "baz", ctxs["foo"])
-	require.Equal(t, "def", ctxs["abc"])
+	require.Equal(t, "baz", ctxs["foo"].Path)
+	require.Equal(t, "def", ctxs["abc"].Path)
 
 	m, _, err = ReadTargets(ctx, []File{fp}, []string{"app"}, []string{"app.contexts.foo=bay", "base.contexts.ghi=jkl"}, nil)
 	require.NoError(t, err)
@@ -402,9 +402,9 @@ func TestReadContexts(t *testing.T) {
 	ctxs = bo["app"].Inputs.NamedContexts
 	require.Equal(t, 3, len(ctxs))
 
-	require.Equal(t, "bay", ctxs["foo"])
-	require.Equal(t, "def", ctxs["abc"])
-	require.Equal(t, "jkl", ctxs["ghi"])
+	require.Equal(t, "bay", ctxs["foo"].Path)
+	require.Equal(t, "def", ctxs["abc"].Path)
+	require.Equal(t, "jkl", ctxs["ghi"].Path)
 
 	// test resetting base values
 	m, _, err = ReadTargets(ctx, []File{fp}, []string{"app"}, []string{"app.contexts.foo="}, nil)
@@ -419,7 +419,7 @@ func TestReadContexts(t *testing.T) {
 
 	ctxs = bo["app"].Inputs.NamedContexts
 	require.Equal(t, 1, len(ctxs))
-	require.Equal(t, "def", ctxs["abc"])
+	require.Equal(t, "def", ctxs["abc"].Path)
 }
 
 func TestReadContextFromTargetUnknown(t *testing.T) {

build/build.go

@@ -84,7 +84,12 @@ type Inputs struct {
 	InStream         io.Reader
 	ContextState     *llb.State
 	DockerfileInline string
-	NamedContexts    map[string]string
+	NamedContexts    map[string]NamedContext
+}
+
+type NamedContext struct {
+	Path  string
+	State *llb.State
 }
 
 type DriverInfo struct {
@@ -1160,11 +1165,20 @@ func LoadInputs(ctx context.Context, d driver.Driver, inp Inputs, pw progress.Wr
 
 	for k, v := range inp.NamedContexts {
 		target.FrontendAttrs["frontend.caps"] = "moby.buildkit.frontend.contexts+forward"
-		if urlutil.IsGitURL(v) || urlutil.IsURL(v) || strings.HasPrefix(v, "docker-image://") || strings.HasPrefix(v, "target:") {
-			target.FrontendAttrs["context:"+k] = v
+		if v.State != nil {
+			target.FrontendAttrs["context:"+k] = "input:" + k
+			if target.FrontendInputs == nil {
+				target.FrontendInputs = make(map[string]llb.State)
+			}
+			target.FrontendInputs[k] = *v.State
 			continue
 		}
-		st, err := os.Stat(v)
+
+		if urlutil.IsGitURL(v.Path) || urlutil.IsURL(v.Path) || strings.HasPrefix(v.Path, "docker-image://") || strings.HasPrefix(v.Path, "target:") {
+			target.FrontendAttrs["context:"+k] = v.Path
+			continue
+		}
+		st, err := os.Stat(v.Path)
 		if err != nil {
 			return nil, errors.Wrapf(err, "failed to get build context %v", k)
 		}
@@ -1175,7 +1189,7 @@ func LoadInputs(ctx context.Context, d driver.Driver, inp Inputs, pw progress.Wr
 		if k == "context" || k == "dockerfile" {
 			localName = "_" + k // underscore to avoid collisions
 		}
-		target.LocalDirs[localName] = v
+		target.LocalDirs[localName] = v.Path
 		target.FrontendAttrs["context:"+k] = "local:" + localName
 	}
 

commands/build.go

@@ -480,11 +480,11 @@ func listToMap(values []string, defaultEnv bool) map[string]string {
 	return result
 }
 
-func parseContextNames(values []string) (map[string]string, error) {
+func parseContextNames(values []string) (map[string]build.NamedContext, error) {
 	if len(values) == 0 {
 		return nil, nil
 	}
-	result := make(map[string]string, len(values))
+	result := make(map[string]build.NamedContext, len(values))
 	for _, value := range values {
 		kv := strings.SplitN(value, "=", 2)
 		if len(kv) != 2 {
@@ -495,7 +495,7 @@ func parseContextNames(values []string) (map[string]string, error) {
 			return nil, errors.Wrapf(err, "invalid context name %s", kv[0])
 		}
 		name := strings.TrimSuffix(reference.FamiliarString(named), ":latest")
-		result[name] = kv[1]
+		result[name] = build.NamedContext{Path: kv[1]}
 	}
 	return result, nil
 }