http: control GSSAPI credential delegation

Delegation of credentials is disabled by default in libcurl since
version 7.21.7 due to security vulnerability CVE-2011-2192. Which
makes troubles with GSS/kerberos authentication when delegation
of credentials is required. This can be changed with option
CURLOPT_GSSAPI_DELEGATION in libcurl with set expected parameter
since libcurl version 7.22.0.

This patch provides new configuration variable http.delegation
which corresponds to curl parameter "--delegation" (see man 1 curl).

The following values are supported:

* none (default).
* policy
* always

Signed-off-by: Petr Stodulka <pstodulk@redhat.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/config.txt b/Documentation/config.txt
index 0bcb679..c588168 100644 (file)
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -1730,6 +1730,20 @@ http.emptyAuth::
        a username in the URL, as libcurl normally requires a username for
        authentication.
 
+http.delegation::
+       Control GSSAPI credential delegation. The delegation is disabled
+       by default in libcurl since version 7.21.7. Set parameter to tell
+       the server what it is allowed to delegate when it comes to user
+       credentials. Used with GSS/kerberos. Possible values are:
++
+--
+* `none` - Don't allow any delegation.
+* `policy` - Delegates if and only if the OK-AS-DELEGATE flag is set in the
+  Kerberos service ticket, which is a matter of realm policy.
+* `always` - Unconditionally allow the server to delegate.
+--
+
+
 http.extraHeader::
        Pass an additional HTTP header when communicating with a server.  If
        more than one such entry exists, all of them are added as extra

diff --git a/http.c b/http.c
index cd40b01..624f0ce 100644 (file)
--- a/http.c
+++ b/http.c
@@ -90,6 +90,18 @@ static struct {
         * here, too
         */
 };
+#if LIBCURL_VERSION_NUM >= 0x071600
+static const char *curl_deleg;
+static struct {
+       const char *name;
+       long curl_deleg_param;
+} curl_deleg_levels[] = {
+       { "none", CURLGSSAPI_DELEGATION_NONE },
+       { "policy", CURLGSSAPI_DELEGATION_POLICY_FLAG },
+       { "always", CURLGSSAPI_DELEGATION_FLAG },
+};
+#endif
+
 static struct credential proxy_auth = CREDENTIAL_INIT;
 static const char *curl_proxyuserpwd;
 static const char *curl_cookie_file;
@@ -316,6 +328,15 @@ static int http_options(const char *var, const char *value, void *cb)
                return 0;
        }
 
+       if (!strcmp("http.delegation", var)) {
+#if LIBCURL_VERSION_NUM >= 0x071600
+               return git_config_string(&curl_deleg, var, value);
+#else
+               warning(_("Delegation control is not supported with cURL < 7.22.0"));
+               return 0;
+#endif
+       }
+
        if (!strcmp("http.pinnedpubkey", var)) {
 #if LIBCURL_VERSION_NUM >= 0x072c00
                return git_config_pathname(&ssl_pinnedkey, var, value);
@@ -622,6 +643,22 @@ static CURL *get_curl_handle(void)
        curl_easy_setopt(result, CURLOPT_HTTPAUTH, CURLAUTH_ANY);
 #endif
 
+#if LIBCURL_VERSION_NUM >= 0x071600
+       if (curl_deleg) {
+               int i;
+               for (i = 0; i < ARRAY_SIZE(curl_deleg_levels); i++) {
+                       if (!strcmp(curl_deleg, curl_deleg_levels[i].name)) {
+                               curl_easy_setopt(result, CURLOPT_GSSAPI_DELEGATION,
+                                               curl_deleg_levels[i].curl_deleg_param);
+                               break;
+                       }
+               }
+               if (i == ARRAY_SIZE(curl_deleg_levels))
+                       warning("Unknown delegation method '%s': using default",
+                               curl_deleg);
+       }
+#endif
+
        if (http_proactive_auth)
                init_curl_http_auth(result);