Subject: [PATCH 1/2] http: only reject basic auth credentials once they have been tried

From: Quentin Bouget <[email-masked]>
Date: Sun, 4 Feb 2024 19:54:26 +0100

When CURLAUTH_GSSNEGOTIATE is enabled, it is currently assumed that
the provided username/password relate to a GSSAPI auth attempt.
In practice, forges such as gitlab can be deployed with HTTP basic auth
and GSSAPI auth both listening on the same port, meaning just because
the server supports GSSAPI and failed an authentication attempt using
the provided credentials, it does not mean the credentials are not valid
HTTP basic auth credentials.

This is documented as a long running bug here [1] and breaks token-based
authentication when the token is provided in the remote's URL itself.

This commit makes it so credentials are only dropped once they have been
tried both as GSSAPI credentials and HTTP basic auth credentials.

[1] https://gitlab.com/gitlab-org/gitlab/-/blob/b0e0d25646d1992fefda863febdcba8d4c7a1bbf/doc/integration/kerberos.md#L250

Signed-off-by: Quentin Bouget <[email-masked]>
---
 http.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/http.c b/http.c
index e73b136e58..ccea19ac47 100644
--- a/http.c
+++ b/http.c
@@ -1758,10 +1758,7 @@ static int handle_curl_result(struct slot_results *results)
 	} else if (missing_target(results))
 		return HTTP_MISSING_TARGET;
 	else if (results->http_code == 401) {
-		if (http_auth.username && http_auth.password) {
-			credential_reject(&http_auth);
-			return HTTP_NOAUTH;
-		} else {
+		if ((http_auth_methods & CURLAUTH_GSSNEGOTIATE) == CURLAUTH_GSSNEGOTIATE) {
 			http_auth_methods &= ~CURLAUTH_GSSNEGOTIATE;
 			if (results->auth_avail) {
 				http_auth_methods &= results->auth_avail;
@@ -1769,6 +1766,9 @@ static int handle_curl_result(struct slot_results *results)
 			}
 			return HTTP_REAUTH;
 		}
+		if (http_auth.username && http_auth.password)
+			credential_reject(&http_auth);
+		return HTTP_NOAUTH;
 	} else {
 		if (results->http_connectcode == 407)
 			credential_reject(&proxy_auth);
-- 
2.43.0