agent: Add new shadow key type and functions to call tpm2daemon
1f995b9ba42b
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Description

agent: Add new shadow key type and functions to call tpm2daemon

* agent/call-tpm2d.c: New.
* divert-tpm2.c: New.
* agent/Makefile.am: Add new files.
* agent/agent.h (DAEMON_TPM2D): New.  Add stub fucntions.
* agent/call-daemon.c (GNUPG_MODULE_NAME_TPM2DAEMON): New.
* agent/command.c (do_one_keyinfo): Handle tpmv2.
* agent/gpg-agent.c (oTpm2daemonProgram): New.
(opts): New option --tpm2daemon-program.
(parse_rereadable_options): Handle option.
* agent/pkdecrypt.c (agent_pkdecrypt): Divert to tpm2d.
(agent_pksign_do): Ditto.
---

A new shadow key type: "tpm2-v1" is introduced signalling that the
shadowed key is handled by the tpm2daemon. A function to identify
this type is introduced and diversions to the tpm2daemon functions are
conditioned on this function for pkign and pkdecrypt where the same
diversions to scd are currently done. The (info) field of the
shadowed key stores the actual TPM key. The TPM key is encrypted so
only the physical TPM it was created on can read it (so no special
protection is required for the info filed), but if the (info) field
becomes corrupt or damaged, the key will be lost (unlike the token
case, where the key is actually moved inside the token).

Note, this commit adds handling for existing TPM format shadow keys,
but there is still no way to create them.

Additional changes:

Add ChangeLog entries.
Some minor indentation fixes.
agent/Makefile.am (gpg_agent_SOURCES): Change to make distcheck work.
agent/agent.h [!HAVE_LIBTSS]: Do not return -EINVAL but an gpg_error_t. Mark args as unused.
agent/protect.c (agent_is_tpm2_key): Free BUF.