upstream: prepare for multiple names for authmethods

allow authentication methods to have one additional name beyond their
primary name.

allow lookup by this synonym

Use primary name for authentication decisions, e.g. for
PermitRootLogin=publickey

Pass actual invoked name to the authmethods, so they can tell whether they
were requested via the their primary name or synonym.

ok markus@

OpenBSD-Commit-ID: 9e613fcb44b8168823195602ed3d09ffd7994559

1 files changed, 19 insertions, 9 deletions

diff --git a/auth2.c b/auth2.c
index 84d0ed16..bcc61196 100644
--- a/auth2.c
+++ b/auth2.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth2.c,v 1.161 2021/04/03 06:18:40 djm Exp $ */
+/* $OpenBSD: auth2.c,v 1.162 2021/12/19 22:12:07 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *
@@ -331,7 +331,7 @@ input_userauth_request(int type, u_int32_t seq, struct ssh *ssh)
 	m = authmethod_lookup(authctxt, method);
 	if (m != NULL && authctxt->failures < options.max_authtries) {
 		debug2("input_userauth_request: try method %s", method);
-		authenticated =	m->userauth(ssh);
+		authenticated =	m->userauth(ssh, method);
 	}
 	if (!authctxt->authenticated)
 		ensure_minimum_time_since(tstart,
@@ -346,18 +346,26 @@ input_userauth_request(int type, u_int32_t seq, struct ssh *ssh)
 }
 
 void
-userauth_finish(struct ssh *ssh, int authenticated, const char *method,
+userauth_finish(struct ssh *ssh, int authenticated, const char *packet_method,
     const char *submethod)
 {
 	Authctxt *authctxt = ssh->authctxt;
+	Authmethod *m = NULL;
+	const char *method = packet_method;
 	char *methods;
 	int r, partial = 0;
 
-	if (!authctxt->valid && authenticated)
-		fatal("INTERNAL ERROR: authenticated invalid user %s",
-		    authctxt->user);
-	if (authenticated && authctxt->postponed)
-		fatal("INTERNAL ERROR: authenticated and postponed");
+	if (authenticated) {
+		if (!authctxt->valid) {
+			fatal("INTERNAL ERROR: authenticated invalid user %s",
+			    authctxt->user);
+		}
+		if (authctxt->postponed)
+			fatal("INTERNAL ERROR: authenticated and postponed");
+		if ((m = authmethod_lookup(authctxt, method)) == NULL)
+			fatal("INTERNAL ERROR: bad method %s", method);
+		method = m->name; /* prefer primary name to possible synonym */
+	}
 
 	/* Special handling for root */
 	if (authenticated && authctxt->pw->pw_uid == 0 &&
@@ -504,7 +512,9 @@ authmethod_lookup(Authctxt *authctxt, const char *name)
 		for (i = 0; authmethods[i] != NULL; i++)
 			if (authmethods[i]->enabled != NULL &&
 			    *(authmethods[i]->enabled) != 0 &&
-			    strcmp(name, authmethods[i]->name) == 0 &&
+			    (strcmp(name, authmethods[i]->name) == 0 ||
+			    (authmethods[i]->synonym != NULL &&
+			    strcmp(name, authmethods[i]->synonym) == 0)) &&
 			    auth2_method_allowed(authctxt,
 			    authmethods[i]->name, NULL))
 				return authmethods[i];