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gnupg/kbx/backend-support.c

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/* backend-support.c - Supporting functions for the backend.
* Copyright (C) 2019 g10 Code GmbH
*
* This file is part of GnuPG.
*
* GnuPG is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* GnuPG is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <https://www.gnu.org/licenses/>.
* SPDX-License-Identifier: GPL-3.0+
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include "keyboxd.h"
#include "../common/i18n.h"
#include "../common/asshelp.h"
#include "../common/tlv.h"
#include "backend.h"
#include "keybox-defs.h"
/* Common definition part of all backend handle. All definitions of
* this structure must start with these fields. */
struct backend_handle_s
{
enum database_types db_type;
unsigned int backend_id;
};
/* Return a string with the name of the database type T. */
const char *
strdbtype (enum database_types t)
{
switch (t)
{
case DB_TYPE_NONE: return "none";
case DB_TYPE_CACHE:return "cache";
case DB_TYPE_KBX: return "keybox";
case DB_TYPE_SQLITE: return "sqlite";
}
return "?";
}
/* Return a new backend ID. Backend IDs are used to identify backends
* without using the actual object. The number of backend resources
* is limited because they are specified in the config file. Thus an
* overflow check is not required. */
unsigned int
be_new_backend_id (void)
{
static unsigned int last;
return ++last;
}
/* Release the backend described by HD. This is a generic function
* which dispatches to the the actual backend. */
void
be_generic_release_backend (ctrl_t ctrl, backend_handle_t hd)
{
if (!hd)
return;
switch (hd->db_type)
{
case DB_TYPE_NONE:
xfree (hd);
break;
case DB_TYPE_CACHE:
be_cache_release_resource (ctrl, hd);
break;
case DB_TYPE_KBX:
be_kbx_release_resource (ctrl, hd);
break;
case DB_TYPE_SQLITE:
be_sqlite_release_resource (ctrl, hd);
break;
default:
log_error ("%s: faulty backend handle of type %d given\n",
__func__, hd->db_type);
}
}
/* Release the request object REQ. */
void
be_release_request (db_request_t req)
{
db_request_part_t part, partn;
if (!req)
return;
for (part = req->part; part; part = partn)
{
partn = part->next;
be_kbx_release_kbx_hd (part->kbx_hd);
be_sqlite_release_local (part->besqlite);
xfree (part);
}
}
/* Given the backend handle BACKEND_HD and the REQUEST find or
* allocate a request part for that backend and store it at R_PART.
* On error R_PART is set to NULL and an error returned. */
gpg_error_t
be_find_request_part (backend_handle_t backend_hd, db_request_t request,
db_request_part_t *r_part)
{
gpg_error_t err;
db_request_part_t part;
for (part = request->part; part; part = part->next)
if (part->backend_id == backend_hd->backend_id)
break;
if (!part)
{
part = xtrycalloc (1, sizeof *part);
if (!part)
return gpg_error_from_syserror ();
part->backend_id = backend_hd->backend_id;
if (backend_hd->db_type == DB_TYPE_KBX)
{
err = be_kbx_init_request_part (backend_hd, part);
if (err)
{
xfree (part);
return err;
}
}
else if (backend_hd->db_type == DB_TYPE_SQLITE)
{
err = be_sqlite_init_local (backend_hd, part);
if (err)
{
xfree (part);
return err;
}
}
part->next = request->part;
request->part = part;
}
*r_part = part;
return 0;
}
/* Return the public key (BUFFER,BUFLEN) which has the type
* PUBKEY_TYPE to the caller. */
gpg_error_t
be_return_pubkey (ctrl_t ctrl, const void *buffer, size_t buflen,
enum pubkey_types pubkey_type, const unsigned char *ubid,
int is_ephemeral, int is_revoked, int uid_no, int pk_no)
{
gpg_error_t err;
char hexubid[2*UBID_LEN+1];
bin2hex (ubid, UBID_LEN, hexubid);
err = kbxd_status_printf (ctrl, "PUBKEY_INFO", "%d %s %c%c %d %d",
pubkey_type, hexubid,
is_ephemeral? 'e':'-',
is_revoked? 'r':'-',
uid_no, pk_no);
if (err)
goto leave;
if (ctrl->no_data_return)
err = 0;
else
err = kbxd_write_data_line (ctrl, buffer, buflen);
leave:
return err;
}
/* Return true if (BLOB/BLOBLEN) seems to be an X509 certificate. */
int
be_is_x509_blob (const unsigned char *blob, size_t bloblen)
{
const unsigned char *p;
size_t n, objlen, hdrlen;
int class, tag, cons, ndef;
/* An X.509 certificate can be identified by this DER encoding:
*
* 30 82 05 B8 30 82 04 A0 A0 03 02 01 02 02 07 15 46 A0 BF 30 07 39
* ----------- +++++++++++ ----- ++++++++ --------------------------
* SEQUENCE SEQUENCE [0] INTEGER INTEGER
* (tbs) (version) (s/n)
*
* Note that v0 certificates don't have an explict version number.
*/
p = blob;
n = bloblen;
if (parse_ber_header (&p, &n, &class, &tag, &cons, &ndef, &objlen, &hdrlen))
return 0; /* Not a proper BER object. */
if (!(class == CLASS_UNIVERSAL && tag == TAG_SEQUENCE && cons))
return 0; /* Does not start with a sequence. */
if (parse_ber_header (&p, &n, &class, &tag, &cons, &ndef, &objlen, &hdrlen))
return 0; /* Not a proper BER object. */
if (!(class == CLASS_UNIVERSAL && tag == TAG_SEQUENCE && cons))
return 0; /* No TBS sequence. */
if (n < 7 || objlen < 7)
return 0; /* Too short: [0], version and min. s/n required. */
if (parse_ber_header (&p, &n, &class, &tag, &cons, &ndef, &objlen, &hdrlen))
return 0; /* Not a proper BER object. */
if (!(class == CLASS_CONTEXT && tag == 0 && cons))
{
if (class == CLASS_UNIVERSAL && tag == TAG_INTEGER && !cons)
return 1; /* Might be a X.509 v0 cert with implict version. */
return 0; /* No context tag. */
}
if (parse_ber_header (&p, &n, &class, &tag, &cons, &ndef, &objlen, &hdrlen))
return 0; /* Not a proper BER object. */
if (!(class == CLASS_UNIVERSAL && tag == TAG_INTEGER
&& !cons && objlen == 1 && n && (*p == 1 || *p == 2)))
return 0; /* Unknown X.509 version. */
p++; /* Skip version number. */
n--;
if (parse_ber_header (&p, &n, &class, &tag, &cons, &ndef, &objlen, &hdrlen))
return 0; /* Not a proper BER object. */
if (!(class == CLASS_UNIVERSAL && tag == TAG_INTEGER && !cons))
return 0; /* No s/n. */
return 1; /* Looks like an X.509 certificate. */
}
/* Return the public key type and the (primary) fingerprint for
* (BLOB,BLOBLEN). r_UBID must point to a buffer of at least UBID_LEN
* bytes, on success it receives the UBID (primary fingerprint
* truncated 20 octets). R_PKTYPE receives the public key type. */
gpg_error_t
be_ubid_from_blob (const void *blob, size_t bloblen,
enum pubkey_types *r_pktype, char *r_ubid)
{
gpg_error_t err;
if (be_is_x509_blob (blob, bloblen))
{
/* Although libksba has a dedicated function to compute the
* fingerprint we compute it here directly because we know that
* we have the entire certificate here (we checked the start of
* the blob and assume that the length is also okay). */
*r_pktype = PUBKEY_TYPE_X509;
gcry_md_hash_buffer (GCRY_MD_SHA1, r_ubid, blob, bloblen);
err = 0;
}
else
{
struct _keybox_openpgp_info info;
err = _keybox_parse_openpgp (blob, bloblen, NULL, &info);
if (err)
{
log_info ("error parsing OpenPGP blob: %s\n", gpg_strerror (err));
err = gpg_error (GPG_ERR_WRONG_BLOB_TYPE);
}
else
{
*r_pktype = PUBKEY_TYPE_OPGP;
log_assert (info.primary.fprlen >= 20);
memcpy (r_ubid, info.primary.fpr, UBID_LEN);
_keybox_destroy_openpgp_info (&info);
}
}
return err;
}
/* Return a certificates serial number in hex encoding. Caller must
* free the returned string. NULL is returned on error but ERRNO
* might not be set if the certificate and thus Libksba is broken. */
char *
be_get_x509_serial (ksba_cert_t cert)
{
const char *p;
unsigned long n;
char *endp;
p = (const char *)ksba_cert_get_serial (cert);
if (!p)
{
log_debug ("oops: Libksba returned a certificate w/o a serial\n");
return NULL;
}
if (*p != '(')
{
log_debug ("oops: Libksba returned an invalid s-expression\n");
return NULL;
}
p++;
n = strtoul (p, &endp, 10);
p = endp;
if (*p != ':')
{
log_debug ("oops: Libksba returned an invalid s-expression\n");
return NULL;
}
p++;
return bin2hex (p, n, NULL);
}
/* Return the keygrip for the X.509 certificate CERT. The grip is
* stored at KEYGRIP which must have been allocated by the caller
* with a size of KEYGRIP_LEN. */
gpg_error_t
be_get_x509_keygrip (ksba_cert_t cert, unsigned char *keygrip)
{
gpg_error_t err;
size_t n;
ksba_sexp_t p;
gcry_sexp_t s_pkey;
p = ksba_cert_get_public_key (cert);
if (!p)
return gpg_error (GPG_ERR_NO_PUBKEY);
n = gcry_sexp_canon_len (p, 0, NULL, NULL);
if (!n)
{
ksba_free (p);
return gpg_error (GPG_ERR_NO_PUBKEY);
}
err = gcry_sexp_sscan (&s_pkey, NULL, (char*)p, n);
ksba_free (p);
if (err)
return err;
if (!gcry_pk_get_keygrip (s_pkey, keygrip))
err = gpg_error (GPG_ERR_PUBKEY_ALGO);
gcry_sexp_release (s_pkey);
return err;
}
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