/* Encrypt the DEK under the key contained in CERT and return it as a
canonical S-Exp in encval. */
static int
encrypt_dek (const DEK dek, ksba_cert_t cert, unsigned char **encval)
{
gcry_sexp_t s_ciph, s_data, s_pkey;
int rc;
ksba_sexp_t buf;
size_t len;
*encval = NULL;
/* get the key from the cert */
buf = ksba_cert_get_public_key (cert);
if (!buf)
{
log_error ("no public key for recipient\n");
return gpg_error (GPG_ERR_NO_PUBKEY);
}
len = gcry_sexp_canon_len (buf, 0, NULL, NULL);
if (!len)
{
log_error ("libksba did not return a proper S-Exp\n");
return gpg_error (GPG_ERR_BUG);
}
rc = gcry_sexp_sscan (&s_pkey, NULL, (char*)buf, len);
xfree (buf); buf = NULL;
if (rc)
{
log_error ("gcry_sexp_scan failed: %s\n", gpg_strerror (rc));
return rc;
}
/* Put the encoded cleartext into a simple list. */
s_data = NULL; /* (avoid compiler warning) */
rc = encode_session_key (dek, &s_data);
if (rc)
{
log_error ("encode_session_key failed: %s\n", gpg_strerror (rc));
return rc;
}
/* pass it to libgcrypt */
rc = gcry_pk_encrypt (&s_ciph, s_data, s_pkey);
gcry_sexp_release (s_data);
gcry_sexp_release (s_pkey);
/* Reformat it. */
if (!rc)
{
rc = make_canon_sexp (s_ciph, encval, NULL);
gcry_sexp_release (s_ciph);
}
return rc;
}
/* Return the information about the secret key specified by the binary
keygrip GRIP. If the key is a shadowed one the shadow information
will be stored at the address R_SHADOW_INFO as an allocated
S-expression. */
gpg_error_t
agent_key_info_from_file (ctrl_t ctrl, const unsigned char *grip,
int *r_keytype, unsigned char **r_shadow_info)
{
gpg_error_t err;
unsigned char *buf;
size_t len;
int keytype;
(void)ctrl;
if (r_keytype)
*r_keytype = PRIVATE_KEY_UNKNOWN;
if (r_shadow_info)
*r_shadow_info = NULL;
{
gcry_sexp_t sexp;
err = read_key_file (grip, &sexp);
if (err)
{
if (gpg_err_code (err) == GPG_ERR_ENOENT)
return gpg_error (GPG_ERR_NOT_FOUND);
else
return err;
}
err = make_canon_sexp (sexp, &buf, &len);
gcry_sexp_release (sexp);
if (err)
return err;
}
keytype = agent_private_key_type (buf);
switch (keytype)
{
case PRIVATE_KEY_CLEAR:
break;
case PRIVATE_KEY_PROTECTED:
/* If we ever require it we could retrieve the comment fields
from such a key. */
break;
case PRIVATE_KEY_SHADOWED:
if (r_shadow_info)
{
const unsigned char *s;
size_t n;
err = agent_get_shadow_info (buf, &s);
if (!err)
{
n = gcry_sexp_canon_len (s, 0, NULL, NULL);
assert (n);
*r_shadow_info = xtrymalloc (n);
if (!*r_shadow_info)
err = gpg_error_from_syserror ();
else
memcpy (*r_shadow_info, s, n);
}
}
break;
default:
err = gpg_error (GPG_ERR_BAD_SECKEY);
break;
}
if (!err && r_keytype)
*r_keytype = keytype;
xfree (buf);
return err;
}
/* Transform a sig-val style s-expression as returned by Libgcrypt to
one which includes an algorithm identifier encoding the public key
and the hash algorithm. The public key algorithm is taken directly
from SIGVAL and the hash algorithm is given by MDALGO. This is
required because X.509 merges the public key algorithm and the hash
algorithm into one OID but Libgcrypt is not aware of that. The
function ignores missing parameters so that it can also be used to
create an siginfo value as expected by ksba_certreq_set_siginfo.
To create a siginfo s-expression a public-key s-expression may be
used instead of a sig-val. We only support RSA for now. */
gpg_error_t
transform_sigval (const unsigned char *sigval, size_t sigvallen, int mdalgo,
unsigned char **r_newsigval, size_t *r_newsigvallen)
{
gpg_error_t err;
const unsigned char *buf, *tok;
size_t buflen, toklen;
int depth, last_depth1, last_depth2;
int is_pubkey = 0;
const unsigned char *rsa_s = NULL;
size_t rsa_s_len;
const char *oid;
gcry_sexp_t sexp;
*r_newsigval = NULL;
if (r_newsigvallen)
*r_newsigvallen = 0;
buf = sigval;
buflen = sigvallen;
depth = 0;
if ((err = parse_sexp (&buf, &buflen, &depth, &tok, &toklen)))
return err;
if ((err = parse_sexp (&buf, &buflen, &depth, &tok, &toklen)))
return err;
if (tok && toklen == 7 && !memcmp ("sig-val", tok, toklen))
;
else if (tok && toklen == 10 && !memcmp ("public-key", tok, toklen))
is_pubkey = 1;
else
return gpg_error (GPG_ERR_UNKNOWN_SEXP);
if ((err = parse_sexp (&buf, &buflen, &depth, &tok, &toklen)))
return err;
if ((err = parse_sexp (&buf, &buflen, &depth, &tok, &toklen)))
return err;
if (!tok || toklen != 3 || memcmp ("rsa", tok, toklen))
return gpg_error (GPG_ERR_WRONG_PUBKEY_ALGO);
last_depth1 = depth;
while (!(err = parse_sexp (&buf, &buflen, &depth, &tok, &toklen))
&& depth && depth >= last_depth1)
{
if (tok)
return gpg_error (GPG_ERR_UNKNOWN_SEXP);
if ((err = parse_sexp (&buf, &buflen, &depth, &tok, &toklen)))
return err;
if (tok && toklen == 1)
{
const unsigned char **mpi;
size_t *mpi_len;
switch (*tok)
{
case 's': mpi = &rsa_s; mpi_len = &rsa_s_len; break;
default: mpi = NULL; mpi_len = NULL; break;
}
if (mpi && *mpi)
return gpg_error (GPG_ERR_DUP_VALUE);
if ((err = parse_sexp (&buf, &buflen, &depth, &tok, &toklen)))
return err;
if (tok && mpi)
{
*mpi = tok;
*mpi_len = toklen;
}
}
/* Skip to the end of the list. */
last_depth2 = depth;
while (!(err = parse_sexp (&buf, &buflen, &depth, &tok, &toklen))
&& depth && depth >= last_depth2)
;
if (err)
return err;
}
if (err)
return err;
/* Map the hash algorithm to an OID. */
switch (mdalgo)
{
case GCRY_MD_SHA1:
oid = "1.2.840.113549.1.1.5"; /* sha1WithRSAEncryption */
break;
case GCRY_MD_SHA256:
oid = "1.2.840.113549.1.1.11"; /* sha256WithRSAEncryption */
break;
case GCRY_MD_SHA384:
oid = "1.2.840.113549.1.1.12"; /* sha384WithRSAEncryption */
break;
case GCRY_MD_SHA512:
oid = "1.2.840.113549.1.1.13"; /* sha512WithRSAEncryption */
break;
default:
return gpg_error (GPG_ERR_DIGEST_ALGO);
}
if (rsa_s && !is_pubkey)
err = gcry_sexp_build (&sexp, NULL, "(sig-val(%s(s%b)))",
oid, (int)rsa_s_len, rsa_s);
else
err = gcry_sexp_build (&sexp, NULL, "(sig-val(%s))", oid);
if (err)
return err;
err = make_canon_sexp (sexp, r_newsigval, r_newsigvallen);
gcry_sexp_release (sexp);
return err;
}
/* Return the secret key as an S-Exp in RESULT after locating it using
the GRIP. Stores NULL at RESULT if the operation shall be diverted
to a token; in this case an allocated S-expression with the
shadow_info part from the file is stored at SHADOW_INFO.
CACHE_MODE defines now the cache shall be used. DESC_TEXT may be
set to present a custom description for the pinentry. LOOKUP_TTL
is an optional function to convey a TTL to the cache manager; we do
not simply pass the TTL value because the value is only needed if an
unprotect action was needed and looking up the TTL may have some
overhead (e.g. scanning the sshcontrol file). */
gpg_error_t
agent_key_from_file (ctrl_t ctrl, const char *desc_text,
const unsigned char *grip, unsigned char **shadow_info,
cache_mode_t cache_mode, lookup_ttl_t lookup_ttl,
gcry_sexp_t *result)
{
int rc;
unsigned char *buf;
size_t len, buflen, erroff;
gcry_sexp_t s_skey;
int got_shadow_info = 0;
*result = NULL;
if (shadow_info)
*shadow_info = NULL;
rc = read_key_file (grip, &s_skey);
if (rc)
return rc;
/* For use with the protection functions we also need the key as an
canonical encoded S-expression in a buffer. Create this buffer
now. */
rc = make_canon_sexp (s_skey, &buf, &len);
if (rc)
return rc;
switch (agent_private_key_type (buf))
{
case PRIVATE_KEY_CLEAR:
break; /* no unprotection needed */
case PRIVATE_KEY_PROTECTED:
{
char *desc_text_final;
char *comment = NULL;
/* Note, that we will take the comment as a C string for
display purposes; i.e. all stuff beyond a Nul character is
ignored. */
{
gcry_sexp_t comment_sexp;
comment_sexp = gcry_sexp_find_token (s_skey, "comment", 0);
if (comment_sexp)
comment = gcry_sexp_nth_string (comment_sexp, 1);
gcry_sexp_release (comment_sexp);
}
desc_text_final = NULL;
if (desc_text)
rc = modify_description (desc_text, comment? comment:"", s_skey,
&desc_text_final);
gcry_free (comment);
if (!rc)
{
rc = unprotect (ctrl, desc_text_final, &buf, grip,
cache_mode, lookup_ttl);
if (rc)
log_error ("failed to unprotect the secret key: %s\n",
gpg_strerror (rc));
}
xfree (desc_text_final);
}
break;
case PRIVATE_KEY_SHADOWED:
if (shadow_info)
{
const unsigned char *s;
size_t n;
rc = agent_get_shadow_info (buf, &s);
if (!rc)
{
n = gcry_sexp_canon_len (s, 0, NULL,NULL);
assert (n);
*shadow_info = xtrymalloc (n);
if (!*shadow_info)
rc = out_of_core ();
else
{
memcpy (*shadow_info, s, n);
rc = 0;
got_shadow_info = 1;
}
}
if (rc)
log_error ("get_shadow_info failed: %s\n", gpg_strerror (rc));
}
else
rc = gpg_error (GPG_ERR_UNUSABLE_SECKEY);
break;
default:
log_error ("invalid private key format\n");
rc = gpg_error (GPG_ERR_BAD_SECKEY);
break;
}
gcry_sexp_release (s_skey);
s_skey = NULL;
if (rc || got_shadow_info)
{
xfree (buf);
return rc;
}
buflen = gcry_sexp_canon_len (buf, 0, NULL, NULL);
rc = gcry_sexp_sscan (&s_skey, &erroff, (char*)buf, buflen);
wipememory (buf, buflen);
xfree (buf);
if (rc)
{
log_error ("failed to build S-Exp (off=%u): %s\n",
(unsigned int)erroff, gpg_strerror (rc));
return rc;
}
*result = s_skey;
return 0;
}
/* Delete the key with GRIP from the disk after having asked for
confirmation using DESC_TEXT. If FORCE is set the function won't
require a confirmation via Pinentry or warns if the key is also
used by ssh.
Common error codes are:
GPG_ERR_NO_SECKEY
GPG_ERR_KEY_ON_CARD
GPG_ERR_NOT_CONFIRMED
*/
gpg_error_t
agent_delete_key (ctrl_t ctrl, const char *desc_text,
const unsigned char *grip, int force)
{
gpg_error_t err;
gcry_sexp_t s_skey = NULL;
unsigned char *buf = NULL;
size_t len;
char *desc_text_final = NULL;
char *comment = NULL;
ssh_control_file_t cf = NULL;
char hexgrip[40+4+1];
char *default_desc = NULL;
err = read_key_file (grip, &s_skey);
if (gpg_err_code (err) == GPG_ERR_ENOENT)
err = gpg_error (GPG_ERR_NO_SECKEY);
if (err)
goto leave;
err = make_canon_sexp (s_skey, &buf, &len);
if (err)
goto leave;
switch (agent_private_key_type (buf))
{
case PRIVATE_KEY_CLEAR:
case PRIVATE_KEY_OPENPGP_NONE:
case PRIVATE_KEY_PROTECTED:
bin2hex (grip, 20, hexgrip);
if (!force)
{
if (!desc_text)
{
default_desc = xtryasprintf
(L_("Do you really want to delete the key identified by keygrip%%0A"
" %s%%0A %%C%%0A?"), hexgrip);
desc_text = default_desc;
}
/* Note, that we will take the comment as a C string for
display purposes; i.e. all stuff beyond a Nul character is
ignored. */
{
gcry_sexp_t comment_sexp;
comment_sexp = gcry_sexp_find_token (s_skey, "comment", 0);
if (comment_sexp)
comment = gcry_sexp_nth_string (comment_sexp, 1);
gcry_sexp_release (comment_sexp);
}
if (desc_text)
err = modify_description (desc_text, comment? comment:"", s_skey,
&desc_text_final);
if (err)
goto leave;
err = agent_get_confirmation (ctrl, desc_text_final,
L_("Delete key"), L_("No"), 0);
if (err)
goto leave;
cf = ssh_open_control_file ();
if (cf)
{
if (!ssh_search_control_file (cf, hexgrip, NULL, NULL, NULL))
{
err = agent_get_confirmation
(ctrl,
L_("Warning: This key is also listed for use with SSH!\n"
"Deleting the key might remove your ability to "
"access remote machines."),
L_("Delete key"), L_("No"), 0);
if (err)
goto leave;
}
}
}
err = remove_key_file (grip);
break;
case PRIVATE_KEY_SHADOWED:
err = remove_key_file (grip);
break;
default:
log_error ("invalid private key format\n");
err = gpg_error (GPG_ERR_BAD_SECKEY);
break;
}
leave:
ssh_close_control_file (cf);
gcry_free (comment);
xfree (desc_text_final);
xfree (default_desc);
xfree (buf);
gcry_sexp_release (s_skey);
return err;
}