From: Yann Ylavic <ylavic@apache.org>
Date: Mon, 18 Jan 2021 17:01:53 +0000 (+0000)
Subject: mod_auth_digest: Fast validation of the nonce's base64 to fail early if
X-Git-Tag: 2.5.0-alpha2-ci-test-only~1046
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=567a10dc479ef52d14fa8e1f2506484542606c6c;p=thirdparty%2Fapache%2Fhttpd.git

mod_auth_digest: Fast validation of the nonce's base64 to fail early if
                 the format can't match anyway.



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1885659 13f79535-47bb-0310-9956-ffa450edef68
---

diff --git a/changes-entries/auth_digest_nonce.txt b/changes-entries/auth_digest_nonce.txt
new file mode 100644
index 00000000000..6a583f6a71f
--- /dev/null
+++ b/changes-entries/auth_digest_nonce.txt
@@ -0,0 +1,3 @@
+  *) mod_auth_digest: Fast validation of the nonce's base64 to fail early if
+     the format can't match anyway.  [Yann Ylavic]
+
diff --git a/modules/aaa/mod_auth_digest.c b/modules/aaa/mod_auth_digest.c
index 480f43bf164..c15514b9eac 100644
--- a/modules/aaa/mod_auth_digest.c
+++ b/modules/aaa/mod_auth_digest.c
@@ -1427,9 +1427,14 @@ static int check_nonce(request_rec *r, digest_header_rec *resp,
     time_rec nonce_time;
     char tmp, hash[NONCE_HASH_LEN+1];
 
-    if (strlen(resp->nonce) != NONCE_LEN) {
+    /* Since the time part of the nonce is a base64 encoding of an
+     * apr_time_t (8 bytes), it should end with a '=', fail early otherwise.
+     */
+    if (strlen(resp->nonce) != NONCE_LEN
+            || resp->nonce[NONCE_TIME_LEN - 1] != '=') {
         ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01775)
-                      "invalid nonce %s received - length is not %d",
+                      "invalid nonce '%s' received - length is not %d "
+                      "or time encoding is incorrect",
                       resp->nonce, NONCE_LEN);
         note_digest_auth_failure(r, conf, resp, 1);
         return HTTP_UNAUTHORIZED;