From e2d271cb6bcd292f786664f055cde41c32002804 Mon Sep 17 00:00:00 2001 From: Stefan Metzmacher Date: Tue, 5 Oct 2021 18:11:57 +0200 Subject: CVE-2020-25719 CVE-2020-25717: auth/gensec: always require a PAC in domain mode (DC or member) AD domains always provide a PAC unless UF_NO_AUTH_DATA_REQUIRED is set on the service account, which can only be explicitly configured, but that's an invalid configuration! We still try to support standalone servers in an MIT realm, as legacy setup. BUG: https://bugzilla.samba.org/show_bug.cgi?id=14801 BUG: https://bugzilla.samba.org/show_bug.cgi?id=14556 Signed-off-by: Stefan Metzmacher Reviewed-by: Andrew Bartlett [jsutton@samba.org Removed knownfail entries] --- auth/gensec/gensec_util.c | 27 +++++++++++++++++++++++---- 1 file changed, 23 insertions(+), 4 deletions(-) (limited to 'auth') diff --git a/auth/gensec/gensec_util.c b/auth/gensec/gensec_util.c index e411751c3af..1075b9fde87 100644 --- a/auth/gensec/gensec_util.c +++ b/auth/gensec/gensec_util.c @@ -25,6 +25,8 @@ #include "auth/gensec/gensec_internal.h" #include "auth/common_auth.h" #include "../lib/util/asn1.h" +#include "param/param.h" +#include "libds/common/roles.h" #undef DBGC_CLASS #define DBGC_CLASS DBGC_AUTH @@ -48,10 +50,27 @@ NTSTATUS gensec_generate_session_info_pac(TALLOC_CTX *mem_ctx, session_info_flags |= AUTH_SESSION_INFO_DEFAULT_GROUPS; if (!pac_blob) { - if (gensec_setting_bool(gensec_security->settings, "gensec", "require_pac", false)) { - DEBUG(1, ("Unable to find PAC in ticket from %s, failing to allow access\n", - principal_string)); - return NT_STATUS_ACCESS_DENIED; + enum server_role server_role = + lpcfg_server_role(gensec_security->settings->lp_ctx); + + /* + * For any domain setup (DC or member) we require having + * a PAC, as the service ticket comes from an AD DC, + * which will always provide a PAC, unless + * UF_NO_AUTH_DATA_REQUIRED is configured for our + * account, but that's just an invalid configuration, + * the admin configured for us! + * + * As a legacy case, we still allow kerberos tickets from an MIT + * realm, but only in standalone mode. In that mode we'll only + * ever accept a kerberos authentication with a keytab file + * being explicitly configured via the 'keytab method' option. + */ + if (server_role != ROLE_STANDALONE) { + DBG_WARNING("Unable to find PAC in ticket from %s, " + "failing to allow access\n", + principal_string); + return NT_STATUS_NO_IMPERSONATION_TOKEN; } DBG_NOTICE("Unable to find PAC for %s, resorting to local " "user lookup\n", principal_string); -- cgit v1.2.1