From 74287f5df9966a0648b4a68417451dd18f079ab8 Mon Sep 17 00:00:00 2001
From: "djm@openbsd.org" <djm@openbsd.org>
Date: Tue, 31 Jul 2018 03:10:27 +0000
Subject: [PATCH] upstream: delay bailout for invalid authentic

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OpenBSD-Commit-ID: b4891882fbe413f230fe8ac8a37349b03bd0b70d
---
 auth2-gss.c       | 11 +++++++----
 auth2-hostbased.c | 11 ++++++-----
 auth2-pubkey.c    | 25 +++++++++++++++----------
 3 files changed, 28 insertions(+), 19 deletions(-)

diff --git a/auth2-gss.c b/auth2-gss.c
index 47308c5ce..9351e0428 100644
--- a/auth2-gss.c
+++ b/auth2-gss.c
@@ -70,9 +70,6 @@ userauth_gssapi(struct ssh *ssh)
 	u_int len;
 	u_char *doid = NULL;
 
-	if (!authctxt->valid || authctxt->user == NULL)
-		return (0);
-
 	mechs = packet_get_int();
 	if (mechs == 0) {
 		debug("Mechanism negotiation is not supported");
@@ -106,6 +103,12 @@ userauth_gssapi(struct ssh *ssh)
 		return (0);
 	}
 
+	if (!authctxt->valid || authctxt->user == NULL) {
+		debug2("%s: disabled because of invalid user", __func__);
+		free(doid);
+		return (0);
+	}
+
 	if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &goid)))) {
 		if (ctxt != NULL)
 			ssh_gssapi_delete_ctx(&ctxt);
diff --git a/auth2-hostbased.c b/auth2-hostbased.c
index 60159a56c..359393291 100644
--- a/auth2-hostbased.c
+++ b/auth2-hostbased.c
@@ -67,10 +67,6 @@ userauth_hostbased(struct ssh *ssh)
 	int pktype;
 	int authenticated = 0;
 
-	if (!authctxt->valid) {
-		debug2("userauth_hostbased: disabled because of invalid user");
-		return 0;
-	}
 	pkalg = packet_get_string(&alen);
 	pkblob = packet_get_string(&blen);
 	chost = packet_get_string(NULL);
@@ -117,6 +113,11 @@ userauth_hostbased(struct ssh *ssh)
 		goto done;
 	}
 
+	if (!authctxt->valid || authctxt->user == NULL) {
+		debug2("%s: disabled because of invalid user", __func__);
+		goto done;
+	}
+
 	service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
 	    authctxt->service;
 	buffer_init(&b);
diff --git a/auth2-pubkey.c b/auth2-pubkey.c
index c4d0f7908..e1c150401 100644
--- a/auth2-pubkey.c
+++ b/auth2-pubkey.c
@@ -89,16 +89,12 @@ userauth_pubkey(struct ssh *ssh)
 {
 	Buffer b;
 	Key *key = NULL;
-	char *pkalg, *userstyle, *pubkey, *fp = NULL;
-	u_char *pkblob, *sig;
+	char *pkalg = NULL, *userstyle = NULL, *pubkey = NULL, *fp = NULL;
+	u_char *pkblob = NULL, *sig = NULL;
 	u_int alen, blen, slen;
 	int have_sig, pktype;
 	int authenticated = 0;
 
-	if (!authctxt->valid) {
-		debug2("%s: disabled because of invalid user", __func__);
-		return 0;
-	}
 	have_sig = packet_get_char();
 	if (datafellows & SSH_BUG_PKAUTH) {
 		debug2("%s: SSH_BUG_PKAUTH", __func__);
@@ -167,6 +163,12 @@ userauth_pubkey(struct ssh *ssh)
 		} else {
 			buffer_put_string(&b, session_id2, session_id2_len);
 		}
+		if (!authctxt->valid || authctxt->user == NULL) {
+			buffer_free(&b);
+			debug2("%s: disabled because of invalid user",
+			    __func__);
+			goto done;
+		}
 		/* reconstruct packet */
 		buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
 		xasprintf(&userstyle, "%s%s%s%s%s", authctxt->user,
@@ -183,7 +184,6 @@ userauth_pubkey(struct ssh *ssh)
 #endif
 		pubkey = sshkey_format_oneline(key, options.fingerprint_hash);
 		auth_info(authctxt, "%s", pubkey);
-
 		/* test for correct signature */
 		authenticated = 0;
 		if (PRIVSEP(user_key_allowed(authctxt->pw, key, 1)) &&
@@ -194,7 +194,6 @@ userauth_pubkey(struct ssh *ssh)
 			free(pubkey);
 		}
 		buffer_free(&b);
-		free(sig);
 	} else {
 		debug("%s: test whether pkalg/pkblob are acceptable for %s %s",
 		    __func__, sshkey_type(key), fp);
@@ -205,6 +204,11 @@ userauth_pubkey(struct ssh *ssh)
 		    __func__, sshkey_type(key), fp);
 		packet_check_eom();
 
+		if (!authctxt->valid || authctxt->user == NULL) {
+			debug2("%s: disabled because of invalid user",
+			    __func__);
+			goto done;
+		}
 		/* XXX fake reply and always send PK_OK ? */
 		/*
 		 * XXX this allows testing whether a user is allowed
@@ -238,6 +242,7 @@ userauth_pubkey(struct ssh *ssh)
 	free(pkalg);
 	free(pkblob);
 	free(fp);
+	free(sig);
 	return authenticated;
 }