From af0e5c2f6933a678c5d4295e733d405f0cb7066c Mon Sep 17 00:00:00 2001
From: dtucker <dtucker>
Date: Thu, 20 Jan 2005 01:43:38 +0000
Subject: [PATCH]  - (dtucker) [auth-pam.c] Bug #971: Prevent leaking
 information about user    existence via keyboard-interactive/pam, in
 conjunction with previous    auth2-chall.c change; with Colin Watson and djm.

---
 ChangeLog  |  3 +++
 auth-pam.c | 15 +++++++++++++--
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 569541d6..d6eff946 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -30,6 +30,9 @@
      behaviour for bsdauth is maintained by checking authctxt->valid in the
      bsdauth driver.  Note that any third-party kbdint drivers will now need
      to be able to handle responses for invalid logins.  ok markus@
+ - (dtucker) [auth-pam.c] Bug #971: Prevent leaking information about user
+   existence via keyboard-interactive/pam, in conjunction with previous
+   auth2-chall.c change; with Colin Watson and djm.
 
 20050118
  - (dtucker) [INSTALL Makefile.in configure.ac survey.sh.in] Implement
diff --git a/auth-pam.c b/auth-pam.c
index 7ecca946..0b79f3a2 100644
--- a/auth-pam.c
+++ b/auth-pam.c
@@ -186,6 +186,7 @@ static int sshpam_account_status = -1;
 static char **sshpam_env = NULL;
 static Authctxt *sshpam_authctxt = NULL;
 static const char *sshpam_password = NULL;
+static char badpw[] = "\b\n\r\177INCORRECT";
 
 /* Some PAM implementations don't implement this */
 #ifndef HAVE_PAM_GETENVLIST
@@ -701,6 +702,12 @@ sshpam_query(void *ctx, char **name, char **info,
 				**prompts = NULL;
 			}
 			if (type == PAM_SUCCESS) {
+				if (!sshpam_authctxt->valid ||
+				    (sshpam_authctxt->pw->pw_uid == 0 &&
+				    options.permit_root_login != PERMIT_YES))
+					fatal("Internal error: PAM auth "
+					    "succeeded when it should have "
+					    "failed");
 				import_environments(&buffer);
 				*num = 0;
 				**echo_on = 0;
@@ -746,7 +753,12 @@ sshpam_respond(void *ctx, u_int num, char **resp)
 		return (-1);
 	}
 	buffer_init(&buffer);
-	buffer_put_cstring(&buffer, *resp);
+	if (sshpam_authctxt->valid &&
+	    (sshpam_authctxt->pw->pw_uid != 0 ||
+	     options.permit_root_login == PERMIT_YES))
+		buffer_put_cstring(&buffer, *resp);
+	else
+		buffer_put_cstring(&buffer, badpw);
 	if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer) == -1) {
 		buffer_free(&buffer);
 		return (-1);
@@ -1093,7 +1105,6 @@ sshpam_auth_passwd(Authctxt *authctxt, const char *password)
 {
 	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 "
-- 
2.45.1