upstream: allow some additional control over the use of ssh-askpass

via $SSH_ASKPASS_REQUIRE, including force-enable/disable. bz#69 ok markus@

OpenBSD-Commit-ID: 3a1e6cbbf6241ddc4405c4246caa2c249f149eb2

1 files changed, 20 insertions, 5 deletions

diff --git a/readpass.c b/readpass.c
index 974d67f0b..69edce306 100644
--- a/readpass.c
+++ b/readpass.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: readpass.c,v 1.61 2020/01/23 07:10:22 dtucker Exp $ */
+/* $OpenBSD: readpass.c,v 1.62 2020/07/14 23:57:01 djm Exp $ */
 /*
  * Copyright (c) 2001 Markus Friedl.  All rights reserved.
  *
@@ -123,11 +123,26 @@ char *
 read_passphrase(const char *prompt, int flags)
 {
         char cr = '\r', *askpass = NULL, *ret, buf[1024];
-        int rppflags, use_askpass = 0, ttyfd;
+        int rppflags, ttyfd, use_askpass = 0, allow_askpass = 0;
         const char *askpass_hint = NULL;
+        const char *s;
+
+        if ((s = getenv("DISPLAY")) != NULL)
+                allow_askpass = *s != '\0';
+        if ((s = getenv(SSH_ASKPASS_REQUIRE_ENV)) != NULL) {
+                if (strcasecmp(s, "force") == 0) {
+                        use_askpass = 1;
+                        allow_askpass = 1;
+                } else if (strcasecmp(s, "prefer") == 0)
+                        use_askpass = allow_askpass;
+                else if (strcasecmp(s, "never") == 0)
+                        allow_askpass = 0;
+        }
 
         rppflags = (flags & RP_ECHO) ? RPP_ECHO_ON : RPP_ECHO_OFF;
-        if (flags & RP_USE_ASKPASS)
+        if (use_askpass)
+                debug("%s: requested to askpass", __func__);
+        else if (flags & RP_USE_ASKPASS)
                 use_askpass = 1;
         else if (flags & RP_ALLOW_STDIN) {
                 if (!isatty(STDIN_FILENO)) {
@@ -153,10 +168,10 @@ read_passphrase(const char *prompt, int flags)
                 }
         }
 
-        if ((flags & RP_USE_ASKPASS) && getenv("DISPLAY") == NULL)
+        if ((flags & RP_USE_ASKPASS) && !allow_askpass)
                 return (flags & RP_ALLOW_EOF) ? NULL : xstrdup("");
 
-        if (use_askpass && getenv("DISPLAY")) {
+        if (use_askpass && allow_askpass) {
                 if (getenv(SSH_ASKPASS_ENV))
                         askpass = getenv(SSH_ASKPASS_ENV);
                 else