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agent: Allow signing with card key even without a stub key.

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* agent/call-scd.c (agent_card_serialno): Allow NULL for R_SERIAL.
(struct readkey_status_parm_s): New.
(readkey_status_cb): New.
(agent_card_readkey): Add optional arg R_KEYREF and change all
callers.
* agent/findkey.c (key_parms_from_sexp): Allow also a "public-key".
* agent/divert-scd.c (ask_for_card): Allow for SHADOW_INFO being NULL.
* agent/pksign.c (agent_pksign_do): Fallback to sign with an on-card
if there is no stub key yet.  Create the stub key.  Also fixed a
misnaming between s_pkey and s_skey.
--

This change allows to create OpenPGP keys directly from a card without
first making sure that a stub key exists.  It is also the less
surprising behaviour.

Signed-off-by: Werner Koch <wk@gnupg.org>
This commit is contained in:
Werner Koch 2020-02-13 11:45:41 +01:00
parent 8c63430d1a
commit 638526d37f
No known key found for this signature in database
GPG key ID: E3FDFF218E45B72B
8 changed files with 172 additions and 32 deletions
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80
agent/pksign.c
View file

@ -294,6 +294,7 @@ agent_pksign_do (ctrl_t ctrl, const char *cache_nonce,
gcry_sexp_t s_hash = NULL;
gcry_sexp_t s_pkey = NULL;
unsigned char *shadow_info = NULL;
int no_shadow_info = 0;
const unsigned char *data;
int datalen;
int check_signature = 0;
@ -315,16 +316,19 @@ agent_pksign_do (ctrl_t ctrl, const char *cache_nonce,
err = agent_key_from_file (ctrl, cache_nonce, desc_text, ctrl->keygrip,
&shadow_info, cache_mode, lookup_ttl,
&s_skey, NULL);
if (err)
if (gpg_err_code (err) == GPG_ERR_NO_SECKEY)
no_shadow_info = 1;
else if (err)
{
if (gpg_err_code (err) != GPG_ERR_NO_SECKEY)
log_error ("failed to read the secret key\n");
log_error ("failed to read the secret key\n");
goto leave;
}
if (shadow_info)
if (shadow_info || no_shadow_info)
{
/* Divert operation to the smartcard */
/* Divert operation to the smartcard. With NO_SHADOW_INFO set
* we don't have the keystub but we want to see whether the key
* is on the active card. */
size_t len;
unsigned char *buf = NULL;
int key_type;
@ -332,18 +336,65 @@ agent_pksign_do (ctrl_t ctrl, const char *cache_nonce,
int is_ECDSA = 0;
int is_EdDSA = 0;
err = agent_public_key_from_file (ctrl, ctrl->keygrip, &s_pkey);
if (err)
if (no_shadow_info)
{
log_error ("failed to read the public key\n");
goto leave;
/* Try to get the public key from the card or fail with the
* original NO_SECKEY error. We also write a stub file (we
* are here only because no stub exists). */
char *serialno;
unsigned char *pkbuf = NULL;
size_t pkbuflen;
char hexgrip[2*KEYGRIP_LEN+1];
char *keyref;
if (agent_card_serialno (ctrl, &serialno, NULL))
{
/* No card availabale or error reading the card. */
err = gpg_error (GPG_ERR_NO_SECKEY);
goto leave;
}
bin2hex (ctrl->keygrip, KEYGRIP_LEN, hexgrip);
if (agent_card_readkey (ctrl, hexgrip, &pkbuf, &keyref))
{
/* No such key on the card. */
xfree (serialno);
err = gpg_error (GPG_ERR_NO_SECKEY);
goto leave;
}
pkbuflen = gcry_sexp_canon_len (pkbuf, 0, NULL, NULL);
err = gcry_sexp_sscan (&s_pkey, NULL, (char*)pkbuf, pkbuflen);
if (err)
{
xfree (serialno);
xfree (pkbuf);
xfree (keyref);
log_error ("%s: corrupted key returned by scdaemon\n", __func__);
goto leave;
}
if (keyref)
agent_write_shadow_key (ctrl->keygrip, serialno, keyref, pkbuf, 0);
xfree (serialno);
xfree (pkbuf);
xfree (keyref);
}
else
{
/* Get the public key from the stub file. */
err = agent_public_key_from_file (ctrl, ctrl->keygrip, &s_pkey);
if (err)
{
log_error ("failed to read the public key\n");
goto leave;
}
}
if (agent_is_eddsa_key (s_skey))
if (agent_is_eddsa_key (s_pkey))
is_EdDSA = 1;
else
{
key_type = agent_is_dsa_key (s_skey);
key_type = agent_is_dsa_key (s_pkey);
if (key_type == 0)
is_RSA = 1;
else if (key_type == GCRY_PK_ECDSA)
@ -354,7 +405,7 @@ agent_pksign_do (ctrl_t ctrl, const char *cache_nonce,
char *desc2 = NULL;
if (desc_text)
agent_modify_description (desc_text, NULL, s_skey, &desc2);
agent_modify_description (desc_text, NULL, s_pkey, &desc2);
err = divert_pksign (ctrl, desc2? desc2 : desc_text,
ctrl->keygrip,
@ -444,7 +495,7 @@ agent_pksign_do (ctrl_t ctrl, const char *cache_nonce,
}
else
{
/* No smartcard, but a private key */
/* No smartcard, but a private key (in S_SKEY). */
int dsaalgo = 0;
/* Put the hash into a sexp */
@ -494,7 +545,8 @@ agent_pksign_do (ctrl_t ctrl, const char *cache_nonce,
/* Check that the signature verification worked and nothing is
* fooling us e.g. by a bug in the signature create code or by
* deliberately introduced faults. Because Libgcrypt 1.7 does this
* for RSA internally there is no need to do it here again. */
* for RSA internally there is no need to do it here again. We do
* this always for card based RSA keys, though. */
if (check_signature)
{
gcry_sexp_t sexp_key = s_pkey? s_pkey: s_skey;