package main
import (
+ "crypto/hmac"
+ "crypto/sha256"
"encoding/xml"
"errors"
"fmt"
"io"
"net/http"
+ "net/url"
"os"
"path/filepath"
"sort"
"strconv"
"strings"
+ "time"
"git.arvados.org/arvados.git/sdk/go/arvados"
"git.arvados.org/arvados.git/sdk/go/ctxlog"
"github.com/AdRoll/goamz/s3"
)
-const s3MaxKeys = 1000
+const (
+ s3MaxKeys = 1000
+ s3SignAlgorithm = "AWS4-HMAC-SHA256"
+ s3MaxClockSkew = 5 * time.Minute
+)
+
+func hmacstring(msg string, key []byte) []byte {
+ h := hmac.New(sha256.New, key)
+ io.WriteString(h, msg)
+ return 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, "&")
+}
+
+func s3signature(alg, secretKey, 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.URL.Host + "\n"
+ } else {
+ canonicalHeaders += h + ":" + r.Header.Get(h) + "\n"
+ }
+ }
+
+ crhash := sha256.New()
+ fmt.Fprintf(crhash, "%s\n%s\n%s\n%s\n%s\n%s", r.Method, r.URL.EscapedPath(), s3querystring(r.URL), canonicalHeaders, signedHeaders, r.Header.Get("X-Amz-Content-Sha256"))
+ crdigest := fmt.Sprintf("%x", crhash.Sum(nil))
+
+ payload := fmt.Sprintf("%s\n%s\n%s\n%s", alg, r.Header.Get("X-Amz-Date"), scope, crdigest)
+
+ // 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])
+ h := hmac.New(sha256.New, key)
+ h.Write([]byte(payload))
+ return fmt.Sprintf("%x", h.Sum(nil)), nil
+}
+
+// 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.Config.cluster.Services.Controller.ExternalURL.Host,
+ Insecure: h.Config.cluster.TLS.Insecure,
+ }).WithRequestID(r.Header.Get("X-Request-Id"))
+ var aca arvados.APIClientAuthorization
+ ctx := arvados.ContextWithAuthorization(r.Context(), "Bearer "+h.Config.cluster.SystemRootToken)
+ err := client.RequestAndDecodeContext(ctx, &aca, "GET", "arvados/v1/api_client_authorizations/"+key, nil, nil)
+ if err != nil {
+ ctxlog.FromContext(ctx).WithError(err).WithField("UUID", key).Info("token lookup failed")
+ return "", errors.New("invalid access key")
+ }
+ expect, err := s3signature(s3SignAlgorithm, aca.APIToken, scope, signedHeaders, r)
+ if err != nil {
+ return "", err
+ } else if expect != signature {
+ return "", errors.New("signature does not match")
+ }
+ return aca.TokenV2(), nil
+}
// serveS3 handles r and returns true if r is a request from an S3
// client, otherwise it returns false.
if auth := r.Header.Get("Authorization"); strings.HasPrefix(auth, "AWS ") {
split := strings.SplitN(auth[4:], ":", 2)
if len(split) < 2 {
- w.WriteHeader(http.StatusUnauthorized)
+ http.Error(w, "malformed Authorization header", http.StatusUnauthorized)
return true
}
token = split[0]
- } else if strings.HasPrefix(auth, "AWS4-HMAC-SHA256 ") {
- for _, cmpt := range strings.Split(auth[17:], ",") {
- cmpt = strings.TrimSpace(cmpt)
- split := strings.SplitN(cmpt, "=", 2)
- if len(split) == 2 && split[0] == "Credential" {
- keyandscope := strings.Split(split[1], "/")
- if len(keyandscope[0]) > 0 {
- token = keyandscope[0]
- break
- }
- }
- }
- if token == "" {
- w.WriteHeader(http.StatusBadRequest)
- fmt.Println(w, "invalid V4 signature")
+ } else if strings.HasPrefix(auth, s3SignAlgorithm+" ") {
+ t, err := h.checks3signature(r)
+ if err != nil {
+ http.Error(w, "signature verification failed: "+err.Error(), http.StatusForbidden)
return true
}
+ token = t
} else {
return false
}
projects / arvados.git / commitdiff