gpg-agent: add new CACHE_MODE_EXPORTdkg/fix-T4522

* agent/agent.h: define CACHE_MODE_EXPORT
* agent/call-pinentry.c (agent_askpin, agent_get_passphrase): use "e/"
as the prefix for SETKEYINFO when in CACHE_MODE_EXPORT.
(agent_clear_passphrase): allow clearing the export cache.
* agent/command.c (cmd_clear_passphrase): add --mode=export.
(cmd_export_key): use CACHE_MODE_EXPORT.
* tests/openpgp/export.scm: no need to feed passphrases during export,
already cached.

----

We don't want secret keys to be able to be exported automatically
based on the same system passphrase cache used by standard decryption
or signing operations.

So we introduce a "export" cache mode which can be used by EXPORT_KEY.

I confess i don't fully understand the changes made to
tests/openpgp/export.scm -- i'm not sure why the passphrase is already
supplied in this case.

Gnupg-Bug-Id: 4522
Signed-off-by: Daniel Kahn Gillmor <[email protected]>

1 files changed, 2 insertions, 1 deletions

diff --git a/agent/agent.h b/agent/agent.h
index 77672bd50..8c4a1d4ba 100644
--- a/agent/agent.h
+++ b/agent/agent.h
@@ -322,7 +322,8 @@ typedef enum
     CACHE_MODE_USER,       /* GET_PASSPHRASE related cache. */
     CACHE_MODE_SSH,        /* SSH related cache. */
     CACHE_MODE_NONCE,      /* This is a non-predictable nonce.  */
-    CACHE_MODE_DATA        /* Arbitrary data.  */
+    CACHE_MODE_DATA,       /* Arbitrary data.  */
+    CACHE_MODE_EXPORT,     /* Exporting secret keys.  */
   }
 cache_mode_t;