From 41923ce06ac149453debe472238e0cca7d5a2e5f Mon Sep 17 00:00:00 2001
From: "djm@openbsd.org" <djm@openbsd.org>
Date: Tue, 22 Jan 2019 12:03:58 +0000
Subject: [PATCH] upstream: Correct some bugs in PKCS#11 token PIN handling at

initial login, the attempt at reading the PIN could be skipped in some cases
especially on devices with integrated PIN readers.

based on patch from Daniel Kucera in bz#2652; ok markus@

OpenBSD-Commit-ID: fad70a61c60610afe8bb0db538c90e343e75e58e
---
 ssh-pkcs11.c | 34 ++++++++++++++++++++++------------
 1 file changed, 22 insertions(+), 12 deletions(-)

diff --git a/ssh-pkcs11.c b/ssh-pkcs11.c
index 384ac1edb..f116e4051 100644
--- a/ssh-pkcs11.c
+++ b/ssh-pkcs11.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-pkcs11.c,v 1.40 2019/01/22 12:00:50 djm Exp $ */
+/* $OpenBSD: ssh-pkcs11.c,v 1.41 2019/01/22 12:03:58 djm Exp $ */
 /*
  * Copyright (c) 2010 Markus Friedl.  All rights reserved.
  * Copyright (c) 2014 Pedro Martelletto. All rights reserved.
@@ -620,26 +620,36 @@ static int
 pkcs11_open_session(struct pkcs11_provider *p, CK_ULONG slotidx, char *pin,
     CK_ULONG user)
 {
-	CK_RV			rv;
+	struct pkcs11_slotinfo	*si;
 	CK_FUNCTION_LIST	*f;
+	CK_RV			rv;
 	CK_SESSION_HANDLE	session;
-	int			login_required, ret;
+	int			login_required, have_pinpad, ret;
 
 	f = p->function_list;
-	login_required = p->slotinfo[slotidx].token.flags & CKF_LOGIN_REQUIRED;
-	if (pin && login_required && !strlen(pin)) {
+	si = &p->slotinfo[slotidx];
+
+	have_pinpad = si->token.flags & CKF_PROTECTED_AUTHENTICATION_PATH;
+	login_required = si->token.flags & CKF_LOGIN_REQUIRED;
+
+	/* fail early before opening session */
+	if (login_required && !have_pinpad && pin != NULL && strlen(pin) == 0) {
 		error("pin required");
 		return (-SSH_PKCS11_ERR_PIN_REQUIRED);
 	}
 	if ((rv = f->C_OpenSession(p->slotlist[slotidx], CKF_RW_SESSION|
-	    CKF_SERIAL_SESSION, NULL, NULL, &session))
-	    != CKR_OK) {
+	    CKF_SERIAL_SESSION, NULL, NULL, &session)) != CKR_OK) {
 		error("C_OpenSession failed: %lu", rv);
 		return (-1);
 	}
-	if (login_required && pin) {
-		rv = f->C_Login(session, user,
-		    (u_char *)pin, strlen(pin));
+	if (login_required) {
+		if (have_pinpad && (pin == NULL || strlen(pin) == 0)) {
+			/* defer PIN entry to the reader keypad */
+			rv = f->C_Login(session, CKU_USER, NULL_PTR, 0);
+		} else {
+			rv = f->C_Login(session, CKU_USER,
+			    (u_char *)pin, strlen(pin));
+		}
 		if (rv != CKR_OK && rv != CKR_USER_ALREADY_LOGGED_IN) {
 			error("C_Login failed: %lu", rv);
 			ret = (rv == CKR_PIN_LOCKED) ?
@@ -649,9 +659,9 @@ pkcs11_open_session(struct pkcs11_provider *p, CK_ULONG slotidx, char *pin,
 				error("C_CloseSession failed: %lu", rv);
 			return (ret);
 		}
-		p->slotinfo[slotidx].logged_in = 1;
+		si->logged_in = 1;
 	}
-	p->slotinfo[slotidx].session = session;
+	si->session = session;
 	return (0);
 }