From: Kevin McCarthy <kevin@8t8.us>
Date: Sun, 31 Dec 2017 03:10:16 +0000 (-0800)
Subject: Disable message security if the backend is not available.
X-Git-Tag: mutt-1-10-rel~96
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=561e106c0760135544e21e7910df777d512d7d5b;p=mutt

Disable message security if the backend is not available.

Gitlab issue #3 exposed an awkward corner case: if mutt is configured
without PGP or S/MIME, and with GPGME, but $crypt_use_gpgme is unset.
In this case, no backend will be available, but WithCrypto will be set
with both APPLICATION_PGP and APPLICATION_SMIME bits.

That will allow various config vars to enable encryption or signing,
even though there will be no backend available to perform them.  The
message security flag might then be set, but when the user hits send,
will end up back at the compose menu due to the error.

The pgp or smime menu might not even be available to clear the
security setting!

Add a check in send.c before the compose menu is invoked, and give a
warning message for the menu ops inside the compose menu.

I believe this should prevent the issue.  However this is a corner
case combined with user misconfiguration, so I don't believe is worth
a large effort to completely eradicate.
---

diff --git a/compose.c b/compose.c
index 80afd97c..dc909c7b 100644
--- a/compose.c
+++ b/compose.c
@@ -1426,6 +1426,11 @@ int mutt_compose_menu (HEADER *msg,   /* structure for new message */
       case OP_COMPOSE_PGP_MENU:
         if (!(WithCrypto & APPLICATION_PGP))
           break;
+        if (!crypt_has_module_backend (APPLICATION_PGP))
+        {
+          mutt_error _("No PGP backend configured");
+          break;
+        }
 	if ((WithCrypto & APPLICATION_SMIME)
             && (msg->security & APPLICATION_SMIME))
 	{
@@ -1458,6 +1463,11 @@ int mutt_compose_menu (HEADER *msg,   /* structure for new message */
       case OP_COMPOSE_SMIME_MENU:
         if (!(WithCrypto & APPLICATION_SMIME))
           break;
+        if (!crypt_has_module_backend (APPLICATION_SMIME))
+        {
+          mutt_error _("No S/MIME backend configured");
+          break;
+        }
 
 	if ((WithCrypto & APPLICATION_PGP)
             && (msg->security & APPLICATION_PGP))
diff --git a/cryptglue.c b/cryptglue.c
index c9fdd9f2..2379fe33 100644
--- a/cryptglue.c
+++ b/cryptglue.c
@@ -112,6 +112,22 @@ void crypt_invoke_message (int type)
     mutt_message _("Invoking S/MIME...");
 }
 
+/* Returns 1 if a module backend is registered for the type */
+int crypt_has_module_backend (int type)
+{
+  if ((WithCrypto & APPLICATION_PGP) &&
+      (type & APPLICATION_PGP) &&
+      crypto_module_lookup (APPLICATION_PGP))
+    return 1;
+
+  if ((WithCrypto & APPLICATION_SMIME) &&
+      (type & APPLICATION_SMIME) &&
+      crypto_module_lookup (APPLICATION_SMIME))
+    return 1;
+
+  return 0;
+}
+
 
 
 /* 
diff --git a/mutt_crypt.h b/mutt_crypt.h
index b6086111..ab81858f 100644
--- a/mutt_crypt.h
+++ b/mutt_crypt.h
@@ -188,6 +188,9 @@ short crypt_is_numerical_keyid (const char *s);
 /* Show a message that a backend will be invoked. */
 void crypt_invoke_message (int type);
 
+/* Returns 1 if a module backend is registered for the type */
+int crypt_has_module_backend (int type);
+
 
 /* Silently forget about a passphrase. */
 void crypt_pgp_void_passphrase (void);
diff --git a/send.c b/send.c
index cae3bb08..bcd54095 100644
--- a/send.c
+++ b/send.c
@@ -1569,6 +1569,18 @@ ci_send_message (int flags,		/* send mode */
       msg->security = 0;
   }
 
+  /* Deal with the corner case where the crypto module backend is not available.
+   * This can happen if configured without pgp/smime and with gpgme, but
+   * $crypt_use_gpgme is unset.
+   */
+  if (msg->security &&
+      !crypt_has_module_backend (msg->security))
+  {
+    mutt_error _("No crypto backend configured.  Disabling message security setting.");
+    mutt_sleep (1);
+    msg->security = 0;
+  }
+
   /* specify a default fcc.  if we are in batchmode, only save a copy of
    * the message if the value of $copy is yes or ask-yes */