+const (
+ s3MaxKeys = 1000
+ s3SignAlgorithm = "AWS4-HMAC-SHA256"
+ s3MaxClockSkew = 5 * time.Minute
+)
+
+type commonPrefix struct {
+ Prefix string
+}
+
+type listV1Resp struct {
+ XMLName string `xml:"http://s3.amazonaws.com/doc/2006-03-01/ ListBucketResult"`
+ s3.ListResp
+ // s3.ListResp marshals an empty tag when
+ // CommonPrefixes is nil, which confuses some clients.
+ // Fix by using this nested struct instead.
+ CommonPrefixes []commonPrefix
+ // Similarly, we need omitempty here, because an empty
+ // tag confuses some clients (e.g.,
+ // github.com/aws/aws-sdk-net never terminates its
+ // paging loop).
+ NextMarker string `xml:"NextMarker,omitempty"`
+ // ListObjectsV2 has a KeyCount response field.
+ KeyCount int
+}
+
+type listV2Resp struct {
+ XMLName string `xml:"http://s3.amazonaws.com/doc/2006-03-01/ ListBucketResult"`
+ IsTruncated bool
+ Contents []s3.Key
+ Name string
+ Prefix string
+ Delimiter string
+ MaxKeys int
+ CommonPrefixes []commonPrefix
+ EncodingType string `xml:",omitempty"`
+ KeyCount int
+ ContinuationToken string `xml:",omitempty"`
+ NextContinuationToken string `xml:",omitempty"`
+ StartAfter string `xml:",omitempty"`
+}
+
+func hmacstring(msg string, key []byte) []byte {
+ h := hmac.New(sha256.New, key)
+ io.WriteString(h, msg)
+ return h.Sum(nil)
+}
+
+func hashdigest(h hash.Hash, payload string) string {
+ io.WriteString(h, payload)
+ return fmt.Sprintf("%x", h.Sum(nil))
+}
+
+// Signing key for given secret key and request attrs.
+func s3signatureKey(key, datestamp, regionName, serviceName string) []byte {
+ return hmacstring("aws4_request",
+ hmacstring(serviceName,
+ hmacstring(regionName,
+ hmacstring(datestamp, []byte("AWS4"+key)))))
+}
+
+// Canonical query string for S3 V4 signature: sorted keys, spaces
+// escaped as %20 instead of +, keyvalues joined with &.
+func s3querystring(u *url.URL) string {
+ keys := make([]string, 0, len(u.Query()))
+ values := make(map[string]string, len(u.Query()))
+ for k, vs := range u.Query() {
+ k = strings.Replace(url.QueryEscape(k), "+", "%20", -1)
+ keys = append(keys, k)
+ for _, v := range vs {
+ v = strings.Replace(url.QueryEscape(v), "+", "%20", -1)
+ if values[k] != "" {
+ values[k] += "&"
+ }
+ values[k] += k + "=" + v
+ }
+ }
+ sort.Strings(keys)
+ for i, k := range keys {
+ keys[i] = values[k]
+ }
+ return strings.Join(keys, "&")
+}
+
+var reMultipleSlashChars = regexp.MustCompile(`//+`)
+
+func s3stringToSign(alg, scope, signedHeaders string, r *http.Request) (string, error) {
+ timefmt, timestr := "20060102T150405Z", r.Header.Get("X-Amz-Date")
+ if timestr == "" {
+ timefmt, timestr = time.RFC1123, r.Header.Get("Date")
+ }
+ t, err := time.Parse(timefmt, timestr)
+ if err != nil {
+ return "", fmt.Errorf("invalid timestamp %q: %s", timestr, err)
+ }
+ if skew := time.Now().Sub(t); skew < -s3MaxClockSkew || skew > s3MaxClockSkew {
+ return "", errors.New("exceeded max clock skew")
+ }
+
+ var canonicalHeaders string
+ for _, h := range strings.Split(signedHeaders, ";") {
+ if h == "host" {
+ canonicalHeaders += h + ":" + r.Host + "\n"
+ } else {
+ canonicalHeaders += h + ":" + r.Header.Get(h) + "\n"
+ }
+ }
+
+ normalizedPath := normalizePath(r.URL.Path)
+ ctxlog.FromContext(r.Context()).Debugf("normalizedPath %q", normalizedPath)
+ canonicalRequest := fmt.Sprintf("%s\n%s\n%s\n%s\n%s\n%s", r.Method, normalizedPath, s3querystring(r.URL), canonicalHeaders, signedHeaders, r.Header.Get("X-Amz-Content-Sha256"))
+ ctxlog.FromContext(r.Context()).Debugf("s3stringToSign: canonicalRequest %s", canonicalRequest)
+ return fmt.Sprintf("%s\n%s\n%s\n%s", alg, r.Header.Get("X-Amz-Date"), scope, hashdigest(sha256.New(), canonicalRequest)), nil
+}
+
+func normalizePath(s string) string {
+ // (url.URL).EscapedPath() would be incorrect here. AWS
+ // documentation specifies the URL path should be normalized
+ // according to RFC 3986, i.e., unescaping ALPHA / DIGIT / "-"
+ // / "." / "_" / "~". The implication is that everything other
+ // than those chars (and "/") _must_ be percent-encoded --
+ // even chars like ";" and "," that are not normally
+ // percent-encoded in paths.
+ out := ""
+ for _, c := range []byte(reMultipleSlashChars.ReplaceAllString(s, "/")) {
+ if (c >= 'a' && c <= 'z') ||
+ (c >= 'A' && c <= 'Z') ||
+ (c >= '0' && c <= '9') ||
+ c == '-' ||
+ c == '.' ||
+ c == '_' ||
+ c == '~' ||
+ c == '/' {
+ out += string(c)
+ } else {
+ out += fmt.Sprintf("%%%02X", c)
+ }
+ }
+ return out
+}
+
+func s3signature(secretKey, scope, signedHeaders, stringToSign string) (string, error) {
+ // scope is {datestamp}/{region}/{service}/aws4_request
+ drs := strings.Split(scope, "/")
+ if len(drs) != 4 {
+ return "", fmt.Errorf("invalid scope %q", scope)
+ }
+ key := s3signatureKey(secretKey, drs[0], drs[1], drs[2])
+ return hashdigest(hmac.New(sha256.New, key), stringToSign), nil
+}
+
+var v2tokenUnderscore = regexp.MustCompile(`^v2_[a-z0-9]{5}-gj3su-[a-z0-9]{15}_`)
+
+func unescapeKey(key string) string {
+ if v2tokenUnderscore.MatchString(key) {
+ // Entire Arvados token, with "/" replaced by "_" to
+ // avoid colliding with the Authorization header
+ // format.
+ return strings.Replace(key, "_", "/", -1)
+ } else if s, err := url.PathUnescape(key); err == nil {
+ return s
+ } else {
+ return key
+ }
+}
+
+// checks3signature verifies the given S3 V4 signature and returns the
+// Arvados token that corresponds to the given accessKey. An error is
+// returned if accessKey is not a valid token UUID or the signature
+// does not match.
+func (h *handler) checks3signature(r *http.Request) (string, error) {
+ var key, scope, signedHeaders, signature string
+ authstring := strings.TrimPrefix(r.Header.Get("Authorization"), s3SignAlgorithm+" ")
+ for _, cmpt := range strings.Split(authstring, ",") {
+ cmpt = strings.TrimSpace(cmpt)
+ split := strings.SplitN(cmpt, "=", 2)
+ switch {
+ case len(split) != 2:
+ // (?) ignore
+ case split[0] == "Credential":
+ keyandscope := strings.SplitN(split[1], "/", 2)
+ if len(keyandscope) == 2 {
+ key, scope = keyandscope[0], keyandscope[1]
+ }
+ case split[0] == "SignedHeaders":
+ signedHeaders = split[1]
+ case split[0] == "Signature":
+ signature = split[1]
+ }
+ }
+
+ client := (&arvados.Client{
+ APIHost: h.Cluster.Services.Controller.ExternalURL.Host,
+ Insecure: h.Cluster.TLS.Insecure,
+ }).WithRequestID(r.Header.Get("X-Request-Id"))
+ var aca arvados.APIClientAuthorization
+ var secret string
+ var err error
+ if len(key) == 27 && key[5:12] == "-gj3su-" {
+ // Access key is the UUID of an Arvados token, secret
+ // key is the secret part.
+ ctx := arvados.ContextWithAuthorization(r.Context(), "Bearer "+h.Cluster.SystemRootToken)
+ err = client.RequestAndDecodeContext(ctx, &aca, "GET", "arvados/v1/api_client_authorizations/"+key, nil, nil)
+ secret = aca.APIToken
+ } else {
+ // Access key and secret key are both an entire
+ // Arvados token or OIDC access token.
+ ctx := arvados.ContextWithAuthorization(r.Context(), "Bearer "+unescapeKey(key))
+ err = client.RequestAndDecodeContext(ctx, &aca, "GET", "arvados/v1/api_client_authorizations/current", nil, nil)
+ secret = key
+ }
+ if err != nil {
+ ctxlog.FromContext(r.Context()).WithError(err).WithField("UUID", key).Info("token lookup failed")
+ return "", errors.New("invalid access key")
+ }
+ stringToSign, err := s3stringToSign(s3SignAlgorithm, scope, signedHeaders, r)
+ if err != nil {
+ return "", err
+ }
+ expect, err := s3signature(secret, scope, signedHeaders, stringToSign)
+ if err != nil {
+ return "", err
+ } else if expect != signature {
+ return "", fmt.Errorf("signature does not match (scope %q signedHeaders %q stringToSign %q)", scope, signedHeaders, stringToSign)
+ }
+ return aca.TokenV2(), nil
+}
+
+func s3ErrorResponse(w http.ResponseWriter, s3code string, message string, resource string, code int) {
+ w.Header().Set("Content-Type", "application/xml")
+ w.Header().Set("X-Content-Type-Options", "nosniff")
+ w.WriteHeader(code)
+ var errstruct struct {
+ Code string
+ Message string
+ Resource string
+ RequestId string
+ }
+ errstruct.Code = s3code
+ errstruct.Message = message
+ errstruct.Resource = resource
+ errstruct.RequestId = ""
+ enc := xml.NewEncoder(w)
+ fmt.Fprint(w, xml.Header)
+ enc.EncodeElement(errstruct, xml.StartElement{Name: xml.Name{Local: "Error"}})
+}
+
+var NoSuchKey = "NoSuchKey"
+var NoSuchBucket = "NoSuchBucket"
+var InvalidArgument = "InvalidArgument"
+var InternalError = "InternalError"
+var UnauthorizedAccess = "UnauthorizedAccess"
+var InvalidRequest = "InvalidRequest"
+var SignatureDoesNotMatch = "SignatureDoesNotMatch"
+
+var reRawQueryIndicatesAPI = regexp.MustCompile(`^[a-z]+(&|$)`)