ui/build/path.go - android_build_soong - Gitiles

 // Copyright 2018 Google Inc. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 package build

 import (
 	"fmt"
 	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
 	"runtime"
 	"strings"

 	"github.com/google/blueprint/microfactory"

 	"android/soong/ui/build/paths"
 	"android/soong/ui/metrics"
 )

 // parsePathDir returns the list of filenames of readable files in a directory.
 // This does not recurse into subdirectories, and does not contain subdirectory
 // names in the list.
 func parsePathDir(dir string) []string {
 	f, err := os.Open(dir)
 	if err != nil {
 		return nil
 	}
 	defer f.Close()

 	if s, err := f.Stat(); err != nil || !s.IsDir() {
 		return nil
 	}

 	infos, err := f.Readdir(-1)
 	if err != nil {
 		return nil
 	}

 	ret := make([]string, 0, len(infos))
 	for _, info := range infos {
 		if m := info.Mode(); !m.IsDir() && m&0111 != 0 {
 			ret = append(ret, info.Name())
 		}
 	}
 	return ret
 }

 // SetupLitePath is the "lite" version of SetupPath used for dumpvars, or other
 // places that does not need the full logging capabilities of path_interposer,
 // wants the minimal performance overhead, and still get the benefits of $PATH
 // hermeticity.
 func SetupLitePath(ctx Context, config Config, tmpDir string) {
 	// Don't replace the path twice.
 	if config.pathReplaced {
 		return
 	}

 	ctx.BeginTrace(metrics.RunSetupTool, "litepath")
 	defer ctx.EndTrace()

 	origPath, _ := config.Environment().Get("PATH")

 	// If tmpDir is empty, the default TMPDIR is used from config.
 	if tmpDir == "" {
 		tmpDir, _ = config.Environment().Get("TMPDIR")
 	}
 	myPath := filepath.Join(tmpDir, "path")
 	ensureEmptyDirectoriesExist(ctx, myPath)

 	os.Setenv("PATH", origPath)
 	// Iterate over the ACL configuration of host tools for this build.
 	for name, pathConfig := range paths.Configuration {
 		if !pathConfig.Symlink {
 			// Excludes 'Forbidden' and 'LinuxOnlyPrebuilt' PathConfigs.
 			continue
 		}

 		origExec, err := exec.LookPath(name)
 		if err != nil {
 			continue
 		}
 		origExec, err = filepath.Abs(origExec)
 		if err != nil {
 			continue
 		}

 		// Symlink allowed host tools into a directory for hermeticity.
 		err = os.Symlink(origExec, filepath.Join(myPath, name))
 		if err != nil {
 			ctx.Fatalln("Failed to create symlink:", err)
 		}
 	}

 	myPath, _ = filepath.Abs(myPath)

 	// Set up the checked-in prebuilts path directory for the current host OS.
 	prebuiltsPath, _ := filepath.Abs("prebuilts/build-tools/path/" + runtime.GOOS + "-x86")
 	myPath = prebuiltsPath + string(os.PathListSeparator) + myPath

 	if value, _ := config.Environment().Get("BUILD_BROKEN_PYTHON_IS_PYTHON2"); value == "true" {
 		py2Path, _ := filepath.Abs("prebuilts/build-tools/path/" + runtime.GOOS + "-x86/py2")
 		if info, err := os.Stat(py2Path); err == nil && info.IsDir() {
 			myPath = py2Path + string(os.PathListSeparator) + myPath
 		}
 	} else if value != "" {
 		ctx.Fatalf("BUILD_BROKEN_PYTHON_IS_PYTHON2 can only be set to 'true' or an empty string, but got %s\n", value)
 	}

 	// Set $PATH to be the directories containing the host tool symlinks, and
 	// the prebuilts directory for the current host OS.
 	config.Environment().Set("PATH", myPath)
 	config.pathReplaced = true
 }

 // SetupPath uses the path_interposer to intercept calls to $PATH binaries, and
 // communicates with the interposer to validate allowed $PATH binaries at
 // runtime, using logs as a medium.
 //
 // This results in hermetic directories in $PATH containing only allowed host
 // tools for the build, and replaces $PATH to contain *only* these directories,
 // and enables an incremental restriction of tools allowed in the $PATH without
 // breaking existing use cases.
 func SetupPath(ctx Context, config Config) {
 	// Don't replace $PATH twice.
 	if config.pathReplaced {
 		return
 	}

 	ctx.BeginTrace(metrics.RunSetupTool, "path")
 	defer ctx.EndTrace()

 	origPath, _ := config.Environment().Get("PATH")
 	// The directory containing symlinks from binaries in $PATH to the interposer.
 	myPath := filepath.Join(config.OutDir(), ".path")
 	interposer := myPath + "_interposer"

 	// Bootstrap the path_interposer Go binary with microfactory.
 	var cfg microfactory.Config
 	cfg.Map("android/soong", "build/soong")
 	cfg.TrimPath, _ = filepath.Abs(".")
 	if _, err := microfactory.Build(&cfg, interposer, "android/soong/cmd/path_interposer"); err != nil {
 		ctx.Fatalln("Failed to build path interposer:", err)
 	}

 	// Save the original $PATH in a file.
 	if err := ioutil.WriteFile(interposer+"_origpath", []byte(origPath), 0777); err != nil {
 		ctx.Fatalln("Failed to write original path:", err)
 	}

 	// Communication with the path interposer works over log entries. Set up the
 	// listener channel for the log entries here.
 	entries, err := paths.LogListener(ctx.Context, interposer+"_log")
 	if err != nil {
 		ctx.Fatalln("Failed to listen for path logs:", err)
 	}

 	// Loop over all log entry listener channels to validate usage of only
 	// allowed PATH tools at runtime.
 	go func() {
 		for log := range entries {
 			curPid := os.Getpid()
 			for i, proc := range log.Parents {
 				if proc.Pid == curPid {
 					log.Parents = log.Parents[i:]
 					break
 				}
 			}
 			// Compute the error message along with the process tree, including
 			// parents, for this log line.
 			procPrints := []string{
 				"See https://android.googlesource.com/platform/build/+/master/Changes.md#PATH_Tools for more information.",
 			}
 			if len(log.Parents) > 0 {
 				procPrints = append(procPrints, "Process tree:")
 				for i, proc := range log.Parents {
 					procPrints = append(procPrints, fmt.Sprintf("%s→ %s", strings.Repeat(" ", i), proc.Command))
 				}
 			}

 			// Validate usage against disallowed or missing PATH tools.
 			config := paths.GetConfig(log.Basename)
 			if config.Error {
 				ctx.Printf("Disallowed PATH tool %q used: %#v", log.Basename, log.Args)
 				for _, line := range procPrints {
 					ctx.Println(line)
 				}
 			} else {
 				ctx.Verbosef("Unknown PATH tool %q used: %#v", log.Basename, log.Args)
 				for _, line := range procPrints {
 					ctx.Verboseln(line)
 				}
 			}
 		}
 	}()

 	// Create the .path directory.
 	ensureEmptyDirectoriesExist(ctx, myPath)

 	// Compute the full list of binaries available in the original $PATH.
 	var execs []string
 	for _, pathEntry := range filepath.SplitList(origPath) {
 		if pathEntry == "" {
 			// Ignore the current directory
 			continue
 		}
 		// TODO(dwillemsen): remove path entries under TOP? or anything
 		// that looks like an android source dir? They won't exist on
 		// the build servers, since they're added by envsetup.sh.
 		// (Except for the JDK, which is configured in ui/build/config.go)

 		execs = append(execs, parsePathDir(pathEntry)...)
 	}

 	if config.Environment().IsEnvTrue("TEMPORARY_DISABLE_PATH_RESTRICTIONS") {
 		ctx.Fatalln("TEMPORARY_DISABLE_PATH_RESTRICTIONS was a temporary migration method, and is now obsolete.")
 	}

 	// Create symlinks from the path_interposer binary to all binaries for each
 	// directory in the original $PATH. This ensures that during the build,
 	// every call to a binary that's expected to be in the $PATH will be
 	// intercepted by the path_interposer binary, and validated with the
 	// LogEntry listener above at build time.
 	for _, name := range execs {
 		if !paths.GetConfig(name).Symlink {
 			// Ignore host tools that shouldn't be symlinked.
 			continue
 		}

 		err := os.Symlink("../.path_interposer", filepath.Join(myPath, name))
 		// Intentionally ignore existing files -- that means that we
 		// just created it, and the first one should win.
 		if err != nil && !os.IsExist(err) {
 			ctx.Fatalln("Failed to create symlink:", err)
 		}
 	}

 	myPath, _ = filepath.Abs(myPath)

 	// We put some prebuilts in $PATH, since it's infeasible to add dependencies
 	// for all of them.
 	prebuiltsPath, _ := filepath.Abs("prebuilts/build-tools/path/" + runtime.GOOS + "-x86")
 	myPath = prebuiltsPath + string(os.PathListSeparator) + myPath

 	if value, _ := config.Environment().Get("BUILD_BROKEN_PYTHON_IS_PYTHON2"); value == "true" {
 		py2Path, _ := filepath.Abs("prebuilts/build-tools/path/" + runtime.GOOS + "-x86/py2")
 		if info, err := os.Stat(py2Path); err == nil && info.IsDir() {
 			myPath = py2Path + string(os.PathListSeparator) + myPath
 		}
 	} else if value != "" {
 		ctx.Fatalf("BUILD_BROKEN_PYTHON_IS_PYTHON2 can only be set to 'true' or an empty string, but got %s\n", value)
 	}

 	// Replace the $PATH variable with the path_interposer symlinks, and
 	// checked-in prebuilts.
 	config.Environment().Set("PATH", myPath)
 	config.pathReplaced = true
 }
	// Copyright 2018 Google Inc. All rights reserved.
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	package build

	import (
	"fmt"
	"io/ioutil"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"strings"

	"github.com/google/blueprint/microfactory"

	"android/soong/ui/build/paths"
	"android/soong/ui/metrics"
	)

	// parsePathDir returns the list of filenames of readable files in a directory.
	// This does not recurse into subdirectories, and does not contain subdirectory
	// names in the list.
	func parsePathDir(dir string) []string {
	f, err := os.Open(dir)
	if err != nil {
	return nil
	}
	defer f.Close()

	if s, err := f.Stat(); err != nil \|\| !s.IsDir() {
	return nil
	}

	infos, err := f.Readdir(-1)
	if err != nil {
	return nil
	}

	ret := make([]string, 0, len(infos))
	for _, info := range infos {
	if m := info.Mode(); !m.IsDir() && m&0111 != 0 {
	ret = append(ret, info.Name())
	}
	}
	return ret
	}

	// SetupLitePath is the "lite" version of SetupPath used for dumpvars, or other
	// places that does not need the full logging capabilities of path_interposer,
	// wants the minimal performance overhead, and still get the benefits of $PATH
	// hermeticity.
	func SetupLitePath(ctx Context, config Config, tmpDir string) {
	// Don't replace the path twice.
	if config.pathReplaced {
	return
	}

	ctx.BeginTrace(metrics.RunSetupTool, "litepath")
	defer ctx.EndTrace()

	origPath, _ := config.Environment().Get("PATH")

	// If tmpDir is empty, the default TMPDIR is used from config.
	if tmpDir == "" {
	tmpDir, _ = config.Environment().Get("TMPDIR")
	}
	myPath := filepath.Join(tmpDir, "path")
	ensureEmptyDirectoriesExist(ctx, myPath)

	os.Setenv("PATH", origPath)
	// Iterate over the ACL configuration of host tools for this build.
	for name, pathConfig := range paths.Configuration {
	if !pathConfig.Symlink {
	// Excludes 'Forbidden' and 'LinuxOnlyPrebuilt' PathConfigs.
	continue
	}

	origExec, err := exec.LookPath(name)
	if err != nil {
	continue
	}
	origExec, err = filepath.Abs(origExec)
	if err != nil {
	continue
	}

	// Symlink allowed host tools into a directory for hermeticity.
	err = os.Symlink(origExec, filepath.Join(myPath, name))
	if err != nil {
	ctx.Fatalln("Failed to create symlink:", err)
	}
	}

	myPath, _ = filepath.Abs(myPath)

	// Set up the checked-in prebuilts path directory for the current host OS.
	prebuiltsPath, _ := filepath.Abs("prebuilts/build-tools/path/" + runtime.GOOS + "-x86")
	myPath = prebuiltsPath + string(os.PathListSeparator) + myPath

	if value, _ := config.Environment().Get("BUILD_BROKEN_PYTHON_IS_PYTHON2"); value == "true" {
	py2Path, _ := filepath.Abs("prebuilts/build-tools/path/" + runtime.GOOS + "-x86/py2")
	if info, err := os.Stat(py2Path); err == nil && info.IsDir() {
	myPath = py2Path + string(os.PathListSeparator) + myPath
	}
	} else if value != "" {
	ctx.Fatalf("BUILD_BROKEN_PYTHON_IS_PYTHON2 can only be set to 'true' or an empty string, but got %s\n", value)
	}

	// Set $PATH to be the directories containing the host tool symlinks, and
	// the prebuilts directory for the current host OS.
	config.Environment().Set("PATH", myPath)
	config.pathReplaced = true
	}

	// SetupPath uses the path_interposer to intercept calls to $PATH binaries, and
	// communicates with the interposer to validate allowed $PATH binaries at
	// runtime, using logs as a medium.
	//
	// This results in hermetic directories in $PATH containing only allowed host
	// tools for the build, and replaces $PATH to contain only these directories,
	// and enables an incremental restriction of tools allowed in the $PATH without
	// breaking existing use cases.
	func SetupPath(ctx Context, config Config) {
	// Don't replace $PATH twice.
	if config.pathReplaced {
	return
	}

	ctx.BeginTrace(metrics.RunSetupTool, "path")
	defer ctx.EndTrace()

	origPath, _ := config.Environment().Get("PATH")
	// The directory containing symlinks from binaries in $PATH to the interposer.
	myPath := filepath.Join(config.OutDir(), ".path")
	interposer := myPath + "_interposer"

	// Bootstrap the path_interposer Go binary with microfactory.
	var cfg microfactory.Config
	cfg.Map("android/soong", "build/soong")
	cfg.TrimPath, _ = filepath.Abs(".")
	if _, err := microfactory.Build(&cfg, interposer, "android/soong/cmd/path_interposer"); err != nil {
	ctx.Fatalln("Failed to build path interposer:", err)
	}

	// Save the original $PATH in a file.
	if err := ioutil.WriteFile(interposer+"_origpath", []byte(origPath), 0777); err != nil {
	ctx.Fatalln("Failed to write original path:", err)
	}

	// Communication with the path interposer works over log entries. Set up the
	// listener channel for the log entries here.
	entries, err := paths.LogListener(ctx.Context, interposer+"_log")
	if err != nil {
	ctx.Fatalln("Failed to listen for path logs:", err)
	}

	// Loop over all log entry listener channels to validate usage of only
	// allowed PATH tools at runtime.
	go func() {
	for log := range entries {
	curPid := os.Getpid()
	for i, proc := range log.Parents {
	if proc.Pid == curPid {
	log.Parents = log.Parents[i:]
	break
	}
	}
	// Compute the error message along with the process tree, including
	// parents, for this log line.
	procPrints := []string{
	"See https://android.googlesource.com/platform/build/+/master/Changes.md#PATH_Tools for more information.",
	}
	if len(log.Parents) > 0 {
	procPrints = append(procPrints, "Process tree:")
	for i, proc := range log.Parents {
	procPrints = append(procPrints, fmt.Sprintf("%s→ %s", strings.Repeat(" ", i), proc.Command))
	}
	}

	// Validate usage against disallowed or missing PATH tools.
	config := paths.GetConfig(log.Basename)
	if config.Error {
	ctx.Printf("Disallowed PATH tool %q used: %#v", log.Basename, log.Args)
	for _, line := range procPrints {
	ctx.Println(line)
	}
	} else {
	ctx.Verbosef("Unknown PATH tool %q used: %#v", log.Basename, log.Args)
	for _, line := range procPrints {
	ctx.Verboseln(line)
	}
	}
	}
	}()

	// Create the .path directory.
	ensureEmptyDirectoriesExist(ctx, myPath)

	// Compute the full list of binaries available in the original $PATH.
	var execs []string
	for _, pathEntry := range filepath.SplitList(origPath) {
	if pathEntry == "" {
	// Ignore the current directory
	continue
	}
	// TODO(dwillemsen): remove path entries under TOP? or anything
	// that looks like an android source dir? They won't exist on
	// the build servers, since they're added by envsetup.sh.
	// (Except for the JDK, which is configured in ui/build/config.go)

	execs = append(execs, parsePathDir(pathEntry)...)
	}

	if config.Environment().IsEnvTrue("TEMPORARY_DISABLE_PATH_RESTRICTIONS") {
	ctx.Fatalln("TEMPORARY_DISABLE_PATH_RESTRICTIONS was a temporary migration method, and is now obsolete.")
	}

	// Create symlinks from the path_interposer binary to all binaries for each
	// directory in the original $PATH. This ensures that during the build,
	// every call to a binary that's expected to be in the $PATH will be
	// intercepted by the path_interposer binary, and validated with the
	// LogEntry listener above at build time.
	for _, name := range execs {
	if !paths.GetConfig(name).Symlink {
	// Ignore host tools that shouldn't be symlinked.
	continue
	}

	err := os.Symlink("../.path_interposer", filepath.Join(myPath, name))
	// Intentionally ignore existing files -- that means that we
	// just created it, and the first one should win.
	if err != nil && !os.IsExist(err) {
	ctx.Fatalln("Failed to create symlink:", err)
	}
	}

	myPath, _ = filepath.Abs(myPath)

	// We put some prebuilts in $PATH, since it's infeasible to add dependencies
	// for all of them.
	prebuiltsPath, _ := filepath.Abs("prebuilts/build-tools/path/" + runtime.GOOS + "-x86")
	myPath = prebuiltsPath + string(os.PathListSeparator) + myPath

	if value, _ := config.Environment().Get("BUILD_BROKEN_PYTHON_IS_PYTHON2"); value == "true" {
	py2Path, _ := filepath.Abs("prebuilts/build-tools/path/" + runtime.GOOS + "-x86/py2")
	if info, err := os.Stat(py2Path); err == nil && info.IsDir() {
	myPath = py2Path + string(os.PathListSeparator) + myPath
	}
	} else if value != "" {
	ctx.Fatalf("BUILD_BROKEN_PYTHON_IS_PYTHON2 can only be set to 'true' or an empty string, but got %s\n", value)
	}

	// Replace the $PATH variable with the path_interposer symlinks, and
	// checked-in prebuilts.
	config.Environment().Set("PATH", myPath)
	config.pathReplaced = true
	}