88 lines
2.5 KiB
Go
88 lines
2.5 KiB
Go
/*
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Copyright 2018 Google LLC
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package util
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import (
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"bufio"
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pkgutil "github.com/GoogleCloudPlatform/container-diff/pkg/util"
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"github.com/GoogleCloudPlatform/k8s-container-builder/pkg/constants"
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"github.com/containers/image/docker"
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"github.com/sirupsen/logrus"
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"io"
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"os"
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"strings"
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)
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var whitelist = []string{"/workspace"}
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// ExtractFileSystemFromImage pulls an image and unpacks it to a file system at root
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func ExtractFileSystemFromImage(img string) error {
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ref, err := docker.ParseReference("//" + img)
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if err != nil {
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return err
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}
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imgSrc, err := ref.NewImageSource(nil)
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if err != nil {
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return err
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}
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whitelist, err := fileSystemWhitelist(constants.WhitelistPath)
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if err != nil {
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return err
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}
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logrus.Infof("Whitelisted directories are %s", whitelist)
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return pkgutil.GetFileSystemFromReference(ref, imgSrc, constants.RootDir, whitelist)
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}
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// Get whitelist from roots of mounted files
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// Each line of /proc/self/mountinfo is in the form:
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// 36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
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// (1)(2)(3) (4) (5) (6) (7) (8) (9) (10) (11)
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// Where (5) is the mount point relative to the process's root
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// From: https://www.kernel.org/doc/Documentation/filesystems/proc.txt
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func fileSystemWhitelist(path string) ([]string, error) {
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f, err := os.Open(path)
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if err != nil {
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return nil, err
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}
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defer f.Close()
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reader := bufio.NewReader(f)
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for {
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line, err := reader.ReadString('\n')
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logrus.Debugf("Read the following line from %s: %s", path, line)
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if err != nil && err != io.EOF {
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return nil, err
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}
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lineArr := strings.Split(line, " ")
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if len(lineArr) < 5 {
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if err == io.EOF {
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logrus.Debugf("Reached end of file %s", path)
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break
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}
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continue
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}
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if lineArr[4] != constants.RootDir {
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logrus.Debugf("Appending %s from line: %s", lineArr[4], line)
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whitelist = append(whitelist, lineArr[4])
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}
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if err == io.EOF {
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logrus.Debugf("Reached end of file %s", path)
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break
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}
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}
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return whitelist, nil
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}
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