- (dtucker) [auth-pam.c] Use an invalid password for root if
PermitRootLogin != yes or the login is invalid, to prevent leaking
information. Based on Openwall's owl-always-auth patch. ok djm@
diff --git a/auth-pam.c b/auth-pam.c
index 8de90a3..b6fc49e 100644
--- a/auth-pam.c
+++ b/auth-pam.c
@@ -31,7 +31,7 @@
/* Based on $FreeBSD: src/crypto/openssh/auth2-pam-freebsd.c,v 1.11 2003/03/31 13:48:18 des Exp $ */
#include "includes.h"
-RCSID("$Id: auth-pam.c,v 1.103 2004/05/30 10:43:59 dtucker Exp $");
+RCSID("$Id: auth-pam.c,v 1.104 2004/05/30 12:04:56 dtucker Exp $");
#ifdef USE_PAM
#if defined(HAVE_SECURITY_PAM_APPL_H)
@@ -1021,6 +1021,7 @@
{
int flags = (options.permit_empty_passwd == 0 ?
PAM_DISALLOW_NULL_AUTHTOK : 0);
+ static char badpw[] = "\b\n\r\177INCORRECT";
if (!options.use_pam || sshpam_handle == NULL)
fatal("PAM: %s called when PAM disabled or failed to "
@@ -1029,6 +1030,15 @@
sshpam_password = password;
sshpam_authctxt = authctxt;
+ /*
+ * If the user logging in is invalid, or is root but is not permitted
+ * by PermitRootLogin, use an invalid password to prevent leaking
+ * information via timing (eg if the PAM config has a delay on fail).
+ */
+ if (!authctxt->valid || (authctxt->pw->pw_uid == 0 &&
+ options.permit_root_login != PERMIT_YES))
+ sshpam_password = badpw;
+
sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
(const void *)&passwd_conv);
if (sshpam_err != PAM_SUCCESS)