agent: Add "ephemeral" Assuan option.

* agent/agent.h (struct ephemeral_private_key_s): New.
(struct server_control_s): Add ephemeral_mode and ephemeral_keys.
(GENKEY_FLAG_NO_PROTECTION, GENKEY_FLAG_PRESET): New.
* agent/genkey.c (clear_ephemeral_keys): New.
(store_key): Add arg ctrl and implement ephemeral_mode.  Change all
callers.
(agent_genkey): Replace args no_protection and preset by a generic new
flags arg.
* agent/findkey.c (wipe_and_fclose): New.
(agent_write_private_key): Add arg ctrl and implement ephemeral_mode.
Change all callers.
(agent_update_private_key): Ditto
(read_key_file): Ditto.
(agent_key_available): Ditto.
* agent/command-ssh.c (card_key_available): Do not update display s/n
in ephemeral mode.  This is however enver triggred.
* agent/gpg-agent.c (agent_deinit_default_ctrl): Cleanup ephemeral
keys.
* agent/command.c (cmd_genkey): Use the new flags instead of separate
vars.
(cmd_readkey): Create a shadow key only in non-ephemeral_mode.
(cmd_getinfo): Add sub-command "ephemeral".
(option_handler): Add option "ephemeral".
--

The idea here that a session can be switched in an ephemeral mode
which does not store or read keys from disk but keeps them local to
the session.

GnuPG-bug-id: 6944

1 files changed, 12 insertions, 10 deletions

diff --git a/agent/learncard.c b/agent/learncard.c
index 8d80b809d..83945b8be 100644
--- a/agent/learncard.c
+++ b/agent/learncard.c
@@ -397,7 +397,7 @@ agent_handle_learn (ctrl_t ctrl, int send, void *assuan_context, int force)
       for (p=item->hexgrip, i=0; i < 20; p += 2, i++)
         grip[i] = xtoi_2 (p);
 
-      if (!force && !agent_key_available (grip))
+      if (!force && !agent_key_available (ctrl, grip))
         continue; /* The key is already available. */
 
       /* Unknown key - store it. */
@@ -408,15 +408,17 @@ agent_handle_learn (ctrl_t ctrl, int send, void *assuan_context, int force)
           goto leave;
         }
 
-      {
-        char *dispserialno;
-
-        agent_card_getattr (ctrl, "$DISPSERIALNO", &dispserialno,
-                            item->hexgrip);
-        rc = agent_write_shadow_key (grip, serialno, item->id, pubkey, force,
-                                     dispserialno);
-        xfree (dispserialno);
-      }
+      if (!ctrl->ephemeral_mode)
+        {
+          char *dispserialno;
+
+          agent_card_getattr (ctrl, "$DISPSERIALNO", &dispserialno,
+                              item->hexgrip);
+          rc = agent_write_shadow_key (ctrl,
+                                       grip, serialno, item->id, pubkey, force,
+                                       dispserialno);
+          xfree (dispserialno);
+        }
       xfree (pubkey);
       if (rc)
         goto leave;