From d190be23688da3ec15a1dad84b1ce9a1337656bb Mon Sep 17 00:00:00 2001
From: Mike Gilbert <floppym@gentoo.org>
Date: Thu, 3 Aug 2023 04:57:23 -0400
Subject: [PATCH] passwordfd: read password during option processing (#420)

When configured to detach from the controlling terminal, pppd closes
file descriptors 0, 1, and 2 before the passwd hook is called. If the
user passes 0, 1, or 2 to the passwordfd option, pppd will fail to read
the password.

To work around this, treat passwordfd as a special option and read the
password during option processing, before pppd closes it.

Bug: https://bugs.gentoo.org/209294

Signed-off-by: Mike Gilbert <floppym@gentoo.org>
---
 pppd/plugins/passwordfd.c | 49 +++++++++++++++++++--------------------
 1 file changed, 24 insertions(+), 25 deletions(-)

diff --git a/pppd/plugins/passwordfd.c b/pppd/plugins/passwordfd.c
index c1f782e..be3088c 100644
--- a/pppd/plugins/passwordfd.c
+++ b/pppd/plugins/passwordfd.c
@@ -24,34 +24,16 @@
 
 char pppd_version[] = PPPD_VERSION;
 
-static int passwdfd = -1;
 static char save_passwd[MAXSECRETLEN];
 
-static struct option options[] = {
-    { "passwordfd", o_int, &passwdfd,
-      "Receive password on this file descriptor" },
-    { NULL }
-};
-
-static int pwfd_check (void)
+static int pwfd_read_password(char **argv)
 {
-    return 1;
-}
+    ssize_t readgood, red;
+    int passwdfd;
+    char passwd[MAXSECRETLEN];
 
-static int pwfd_passwd (char *user, char *passwd)
-{
-    int readgood, red;
-
-    if (passwdfd == -1)
-	return -1;
-
-    if (passwd == NULL)
-	return 1;
-
-    if (passwdfd == -2) {
-	strcpy (passwd, save_passwd);
-	return 1;
-    }
+    if (!ppp_int_option(argv[0], &passwdfd))
+	return 0;
 
     readgood = 0;
     do {
@@ -73,11 +55,28 @@ static int pwfd_passwd (char *user, char *passwd)
 
     passwd[readgood] = 0;
     strcpy (save_passwd, passwd);
-    passwdfd = -2;
 
     return 1;
 }
 
+static struct option options[] = {
+    { "passwordfd", o_special, pwfd_read_password,
+      "Receive password on this file descriptor" },
+    { NULL }
+};
+
+static int pwfd_check (void)
+{
+    return 1;
+}
+
+static int pwfd_passwd (char *user, char *passwd)
+{
+    if (passwd != NULL)
+	strcpy(passwd, save_passwd);
+    return 1;
+}
+
 void plugin_init (void)
 {
     ppp_add_options (options);
-- 
2.39.2