safing-portmaster/base/updater/fetch.go
2024-12-06 12:00:20 +02:00

346 lines
11 KiB
Go

package updater
import (
"bytes"
"context"
"errors"
"fmt"
"hash"
"io"
"net/http"
"net/url"
"os"
"path"
"path/filepath"
"time"
"github.com/safing/jess/filesig"
"github.com/safing/jess/lhash"
"github.com/safing/portmaster/base/log"
"github.com/safing/portmaster/base/utils"
"github.com/safing/portmaster/base/utils/renameio"
)
func (reg *ResourceRegistry) fetchFile(ctx context.Context, client *http.Client, rv *ResourceVersion, tries int) error {
// backoff when retrying
if tries > 0 {
select {
case <-ctx.Done():
return nil // module is shutting down
case <-time.After(time.Duration(tries*tries) * time.Second):
}
}
// check destination dir
dirPath := filepath.Dir(rv.storagePath())
err := reg.storageDir.EnsureAbsPath(dirPath)
if err != nil {
return fmt.Errorf("could not create updates folder: %s", dirPath)
}
// If verification is enabled, download signature first.
var (
verifiedHash *lhash.LabeledHash
sigFileData []byte
)
if rv.resource.VerificationOptions != nil {
verifiedHash, sigFileData, err = reg.fetchAndVerifySigFile(
ctx, client,
rv.resource.VerificationOptions,
rv.versionedSigPath(), rv.SigningMetadata(),
tries,
)
if err != nil {
switch rv.resource.VerificationOptions.DownloadPolicy {
case SignaturePolicyRequire:
return fmt.Errorf("signature verification failed: %w", err)
case SignaturePolicyWarn:
log.Warningf("%s: failed to verify downloaded signature of %s: %s", reg.Name, rv.versionedPath(), err)
case SignaturePolicyDisable:
log.Debugf("%s: failed to verify downloaded signature of %s: %s", reg.Name, rv.versionedPath(), err)
}
}
}
// open file for writing
atomicFile, err := renameio.TempFile(reg.tmpDir.Path, rv.storagePath())
if err != nil {
return fmt.Errorf("could not create temp file for download: %w", err)
}
defer atomicFile.Cleanup() //nolint:errcheck // ignore error for now, tmp dir will be cleaned later again anyway
// start file download
resp, downloadURL, err := reg.makeRequest(ctx, client, rv.versionedPath(), tries)
if err != nil {
return err
}
defer func() {
_ = resp.Body.Close()
}()
// Write to the hasher at the same time, if needed.
var hasher hash.Hash
var writeDst io.Writer = atomicFile
if verifiedHash != nil {
hasher = verifiedHash.Algorithm().RawHasher()
writeDst = io.MultiWriter(hasher, atomicFile)
}
// Download and write file.
n, err := io.Copy(writeDst, resp.Body)
if err != nil {
return fmt.Errorf("failed to download %q: %w", downloadURL, err)
}
if resp.ContentLength != n {
return fmt.Errorf("failed to finish download of %q: written %d out of %d bytes", downloadURL, n, resp.ContentLength)
}
// Before file is finalized, check if hash, if available.
if hasher != nil {
downloadDigest := hasher.Sum(nil)
if verifiedHash.EqualRaw(downloadDigest) {
log.Infof("%s: verified signature of %s", reg.Name, downloadURL)
} else {
switch rv.resource.VerificationOptions.DownloadPolicy {
case SignaturePolicyRequire:
return errors.New("file does not match signed checksum")
case SignaturePolicyWarn:
log.Warningf("%s: checksum does not match file from %s", reg.Name, downloadURL)
case SignaturePolicyDisable:
log.Debugf("%s: checksum does not match file from %s", reg.Name, downloadURL)
}
// Reset hasher to signal that the sig should not be written.
hasher = nil
}
}
// Write signature file, if we have one and if verification succeeded.
if len(sigFileData) > 0 && hasher != nil {
sigFilePath := rv.storagePath() + filesig.Extension
err := os.WriteFile(sigFilePath, sigFileData, 0o0644) //nolint:gosec
if err != nil {
switch rv.resource.VerificationOptions.DownloadPolicy {
case SignaturePolicyRequire:
return fmt.Errorf("failed to write signature file %s: %w", sigFilePath, err)
case SignaturePolicyWarn:
log.Warningf("%s: failed to write signature file %s: %s", reg.Name, sigFilePath, err)
case SignaturePolicyDisable:
log.Debugf("%s: failed to write signature file %s: %s", reg.Name, sigFilePath, err)
}
}
}
// finalize file
err = atomicFile.CloseAtomicallyReplace()
if err != nil {
return fmt.Errorf("%s: failed to finalize file %s: %w", reg.Name, rv.storagePath(), err)
}
// set permissions
// TODO: distinguish between executable and non executable files.
err = utils.SetExecPermission(rv.storagePath(), utils.PublicReadPermission)
if err != nil {
log.Warningf("%s: failed to set permissions on downloaded file %s: %s", reg.Name, rv.storagePath(), err)
}
log.Debugf("%s: fetched %s and stored to %s", reg.Name, downloadURL, rv.storagePath())
return nil
}
func (reg *ResourceRegistry) fetchMissingSig(ctx context.Context, client *http.Client, rv *ResourceVersion, tries int) error {
// backoff when retrying
if tries > 0 {
select {
case <-ctx.Done():
return nil // module is shutting down
case <-time.After(time.Duration(tries*tries) * time.Second):
}
}
// Check destination dir.
dirPath := filepath.Dir(rv.storagePath())
err := reg.storageDir.EnsureAbsPath(dirPath)
if err != nil {
return fmt.Errorf("could not create updates folder: %s", dirPath)
}
// Download and verify the missing signature.
verifiedHash, sigFileData, err := reg.fetchAndVerifySigFile(
ctx, client,
rv.resource.VerificationOptions,
rv.versionedSigPath(), rv.SigningMetadata(),
tries,
)
if err != nil {
switch rv.resource.VerificationOptions.DownloadPolicy {
case SignaturePolicyRequire:
return fmt.Errorf("signature verification failed: %w", err)
case SignaturePolicyWarn:
log.Warningf("%s: failed to verify downloaded signature of %s: %s", reg.Name, rv.versionedPath(), err)
case SignaturePolicyDisable:
log.Debugf("%s: failed to verify downloaded signature of %s: %s", reg.Name, rv.versionedPath(), err)
}
return nil
}
// Check if the signature matches the resource file.
ok, err := verifiedHash.MatchesFile(rv.storagePath())
if err != nil {
switch rv.resource.VerificationOptions.DownloadPolicy {
case SignaturePolicyRequire:
return fmt.Errorf("error while verifying resource file: %w", err)
case SignaturePolicyWarn:
log.Warningf("%s: error while verifying resource file %s", reg.Name, rv.storagePath())
case SignaturePolicyDisable:
log.Debugf("%s: error while verifying resource file %s", reg.Name, rv.storagePath())
}
return nil
}
if !ok {
switch rv.resource.VerificationOptions.DownloadPolicy {
case SignaturePolicyRequire:
return errors.New("resource file does not match signed checksum")
case SignaturePolicyWarn:
log.Warningf("%s: checksum does not match resource file from %s", reg.Name, rv.storagePath())
case SignaturePolicyDisable:
log.Debugf("%s: checksum does not match resource file from %s", reg.Name, rv.storagePath())
}
return nil
}
// Write signature file.
err = os.WriteFile(rv.storageSigPath(), sigFileData, 0o0644) //nolint:gosec
if err != nil {
switch rv.resource.VerificationOptions.DownloadPolicy {
case SignaturePolicyRequire:
return fmt.Errorf("failed to write signature file %s: %w", rv.storageSigPath(), err)
case SignaturePolicyWarn:
log.Warningf("%s: failed to write signature file %s: %s", reg.Name, rv.storageSigPath(), err)
case SignaturePolicyDisable:
log.Debugf("%s: failed to write signature file %s: %s", reg.Name, rv.storageSigPath(), err)
}
}
log.Debugf("%s: fetched %s and stored to %s", reg.Name, rv.versionedSigPath(), rv.storageSigPath())
return nil
}
func (reg *ResourceRegistry) fetchAndVerifySigFile(ctx context.Context, client *http.Client, verifOpts *VerificationOptions, sigFilePath string, requiredMetadata map[string]string, tries int) (*lhash.LabeledHash, []byte, error) {
// Download signature file.
resp, _, err := reg.makeRequest(ctx, client, sigFilePath, tries)
if err != nil {
return nil, nil, err
}
defer func() {
_ = resp.Body.Close()
}()
sigFileData, err := io.ReadAll(resp.Body)
if err != nil {
return nil, nil, err
}
// Extract all signatures.
sigs, err := filesig.ParseSigFile(sigFileData)
switch {
case len(sigs) == 0 && err != nil:
return nil, nil, fmt.Errorf("failed to parse signature file: %w", err)
case len(sigs) == 0:
return nil, nil, errors.New("no signatures found in signature file")
case err != nil:
return nil, nil, fmt.Errorf("failed to parse signature file: %w", err)
}
// Verify all signatures.
var verifiedHash *lhash.LabeledHash
for _, sig := range sigs {
fd, err := filesig.VerifyFileData(
sig,
requiredMetadata,
verifOpts.TrustStore,
)
if err != nil {
return nil, sigFileData, err
}
// Save or check verified hash.
if verifiedHash == nil {
verifiedHash = fd.FileHash()
} else if !fd.FileHash().Equal(verifiedHash) {
// Return an error if two valid hashes mismatch.
// For simplicity, all hash algorithms must be the same for now.
return nil, sigFileData, errors.New("file hashes from different signatures do not match")
}
}
return verifiedHash, sigFileData, nil
}
func (reg *ResourceRegistry) fetchData(ctx context.Context, client *http.Client, downloadPath string, tries int) (fileData []byte, downloadedFrom string, err error) {
// backoff when retrying
if tries > 0 {
select {
case <-ctx.Done():
return nil, "", nil // module is shutting down
case <-time.After(time.Duration(tries*tries) * time.Second):
}
}
// start file download
resp, downloadURL, err := reg.makeRequest(ctx, client, downloadPath, tries)
if err != nil {
return nil, downloadURL, err
}
defer func() {
_ = resp.Body.Close()
}()
// download and write file
buf := bytes.NewBuffer(make([]byte, 0, resp.ContentLength))
n, err := io.Copy(buf, resp.Body)
if err != nil {
return nil, downloadURL, fmt.Errorf("failed to download %q: %w", downloadURL, err)
}
if resp.ContentLength != n {
return nil, downloadURL, fmt.Errorf("failed to finish download of %q: written %d out of %d bytes", downloadURL, n, resp.ContentLength)
}
return buf.Bytes(), downloadURL, nil
}
func (reg *ResourceRegistry) makeRequest(ctx context.Context, client *http.Client, downloadPath string, tries int) (resp *http.Response, downloadURL string, err error) {
// parse update URL
updateBaseURL := reg.UpdateURLs[tries%len(reg.UpdateURLs)]
u, err := url.Parse(updateBaseURL)
if err != nil {
return nil, "", fmt.Errorf("failed to parse update URL %q: %w", updateBaseURL, err)
}
// add download path
u.Path = path.Join(u.Path, downloadPath)
// compile URL
downloadURL = u.String()
// create request
req, err := http.NewRequestWithContext(ctx, http.MethodGet, downloadURL, http.NoBody)
if err != nil {
return nil, "", fmt.Errorf("failed to create request for %q: %w", downloadURL, err)
}
// set user agent
if reg.UserAgent != "" {
req.Header.Set("User-Agent", reg.UserAgent)
}
// start request
resp, err = client.Do(req)
if err != nil {
return nil, "", fmt.Errorf("failed to make request to %q: %w", downloadURL, err)
}
// check return code
if resp.StatusCode != http.StatusOK {
_ = resp.Body.Close()
return nil, "", fmt.Errorf("failed to fetch %q: %d %s", downloadURL, resp.StatusCode, resp.Status)
}
return resp, downloadURL, err
}