/* verify.c - Verify a messages signature
* Copyright (C) 2001 Free Software Foundation, Inc.
*
* 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 2 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, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <time.h>
#include <assert.h>
#include <gcrypt.h>
#include <ksba.h>
#include "gpgsm.h"
#include "keydb.h"
#include "i18n.h"
/* FIXME: Move this to jnlib */
static char *
strtimestamp (time_t atime)
{
char *buffer = xmalloc (15);
if (atime < 0)
strcpy (buffer, "????" "-??" "-??");
else if (!atime)
strcpy (buffer, "none");
else
{
struct tm *tp;
tp = gmtime( &atime );
sprintf (buffer, "%04d-%02d-%02d",
1900+tp->tm_year, tp->tm_mon+1, tp->tm_mday);
}
return buffer;
}
/* fixme: duplicated from import.c */
static void
store_cert (KsbaCert cert)
{
KEYDB_HANDLE kh;
int rc;
kh = keydb_new (0);
if (!kh)
{
log_error (_("failed to allocated keyDB handle\n"));
return;
}
rc = keydb_locate_writable (kh, 0);
if (rc)
log_error (_("error finding writable keyDB: %s\n"), gnupg_strerror (rc));
rc = keydb_insert_cert (kh, cert);
if (rc)
{
log_error (_("error storing certificate: %s\n"), gnupg_strerror (rc));
}
keydb_release (kh);
}
static void
print_integer (unsigned char *p)
{
unsigned long len;
if (!p)
log_printf ("none");
else
{
len = (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3];
for (p+=4; len; len--, p++)
log_printf ("%02X", *p);
}
}
static void
print_time (time_t t)
{
if (!t)
log_printf ("none");
else if ( t == (time_t)(-1) )
log_printf ("error");
else
{
struct tm *tp;
tp = gmtime (&t);
log_printf ("%04d-%02d-%02d %02d:%02d:%02d",
1900+tp->tm_year, tp->tm_mon+1, tp->tm_mday,
tp->tm_hour, tp->tm_min, tp->tm_sec);
assert (!tp->tm_isdst);
}
}
static void
hash_data (int fd, GCRY_MD_HD md)
{
FILE *fp;
char buffer[4096];
int nread;
fp = fdopen ( dup (fd), "rb");
if (!fp)
{
log_error ("fdopen(%d) failed: %s\n", fd, strerror (errno));
return;
}
do
{
nread = fread (buffer, 1, DIM(buffer), fp);
gcry_md_write (md, buffer, nread);
}
while (nread);
if (ferror (fp))
log_error ("read error on fd %d: %s\n", fd, strerror (errno));
fclose (fp);
}
/* Perform a verify operation. To verify detached signatures, data_fd
must be different than -1 */
int
gpgsm_verify (CTRL ctrl, int in_fd, int data_fd)
{
int i, rc;
Base64Context b64reader = NULL;
KsbaError err;
KsbaReader reader;
KsbaCMS cms = NULL;
KsbaStopReason stopreason;
KsbaCert cert;
KEYDB_HANDLE kh;
GCRY_MD_HD data_md = NULL;
int signer;
const char *algoid;
int algo;
int is_detached;
FILE *fp = NULL;
kh = keydb_new (0);
if (!kh)
{
log_error (_("failed to allocated keyDB handle\n"));
rc = GNUPG_General_Error;
goto leave;
}
fp = fdopen ( dup (in_fd), "rb");
if (!fp)
{
log_error ("fdopen() failed: %s\n", strerror (errno));
rc = seterr (IO_Error);
goto leave;
}
rc = gpgsm_create_reader (&b64reader, ctrl, fp, &reader);
if (rc)
{
log_error ("can't create reader: %s\n", gnupg_strerror (rc));
goto leave;
}
cms = ksba_cms_new ();
if (!cms)
{
rc = seterr (Out_Of_Core);
goto leave;
}
err = ksba_cms_set_reader_writer (cms, reader, NULL);
if (err)
{
log_debug ("ksba_cms_set_reader_writer failed: %s\n",
ksba_strerror (err));
rc = map_ksba_err (err);
goto leave;
}
data_md = gcry_md_open (0, 0);
if (!data_md)
{
rc = map_gcry_err (gcry_errno());
log_error ("md_open failed: %s\n", gcry_strerror (-1));
goto leave;
}
if (DBG_HASHING)
gcry_md_start_debug (data_md, "vrfy.data");
is_detached = 0;
do
{
err = ksba_cms_parse (cms, &stopreason);
if (err)
{
log_debug ("ksba_cms_parse failed: %s\n", ksba_strerror (err));
rc = map_ksba_err (err);
goto leave;
}
if (stopreason == KSBA_SR_NEED_HASH)
{
is_detached = 1;
log_debug ("Detached signature\n");
}
if (stopreason == KSBA_SR_BEGIN_DATA)
{
log_error ("error: only detached signatures are supportted\n");
rc = GNUPG_Not_Implemented;
goto leave;
}
if (stopreason == KSBA_SR_NEED_HASH
|| stopreason == KSBA_SR_BEGIN_DATA)
{ /* We are now able to enable the hash algorithms */
for (i=0; (algoid=ksba_cms_get_digest_algo_list (cms, i)); i++)
{
algo = gcry_md_map_name (algoid);
if (!algo)
log_error ("unknown hash algorithm `%s'\n",
algoid? algoid:"?");
else
gcry_md_enable (data_md, algo);
}
if (is_detached)
{
if (data_fd == -1)
{
log_error ("detached signature but no data given\n");
rc = GNUPG_Bad_Signature;
goto leave;
}
hash_data (data_fd, data_md);
}
}
}
while (stopreason != KSBA_SR_READY);
if (data_fd != -1 && !is_detached)
{
log_error ("data given for a non-detached signature\n");
rc = GNUPG_Conflict;
goto leave;
}
for (i=0; (cert=ksba_cms_get_cert (cms, i)); i++)
{
log_debug ("storing certifcate %d\n", i);
/* Fixme: we should mark the stored certificates as temporary
and put them in a cache first */
store_cert (cert);
ksba_cert_release (cert);
}
cert = NULL;
err = 0;
for (signer=0; signer < 1; signer++)
{
char *issuer = NULL;
char *sigval = NULL;
time_t sigtime;
unsigned char *serial;
char *msgdigest = NULL;
size_t msgdigestlen;
err = ksba_cms_get_issuer_serial (cms, signer, &issuer, &serial);
if (err)
break;
log_debug ("signer %d - issuer: `%s'\n", signer, issuer? issuer:"[NONE]");
log_debug ("signer %d - serial: ", signer);
print_integer (serial);
log_printf ("\n");
err = ksba_cms_get_signing_time (cms, signer, &sigtime);
if (err)
{
log_debug ("error getting signing time: %s\n", ksba_strerror (err));
sigtime = (time_t)-1;
}
log_debug ("signer %d - sigtime: ", signer);
print_time (sigtime);
log_printf ("\n");
err = ksba_cms_get_message_digest (cms, signer,
&msgdigest, &msgdigestlen);
if (err)
break;
algoid = ksba_cms_get_digest_algo (cms, signer);
algo = gcry_md_map_name (algoid);
log_debug ("signer %d - digest algo: %d\n", signer, algo);
if ( !gcry_md_info (data_md, GCRYCTL_IS_ALGO_ENABLED, &algo, NULL) )
{
log_debug ("digest algo %d has not been enabled\n", algo);
goto next_signer;
}
sigval = ksba_cms_get_sig_val (cms, signer);
if (!sigval)
{
log_error ("no signature value available\n");
goto next_signer;
}
log_debug ("signer %d - signature: `%s'\n", signer, sigval);
/* Find the certificate of the signer */
keydb_search_reset (kh);
rc = keydb_search_issuer_sn (kh, issuer, serial);
if (rc)
{
log_debug ("failed to find the certificate: %s\n",
gnupg_strerror(rc));
goto next_signer;
}
rc = keydb_get_cert (kh, &cert);
if (rc)
{
log_debug ("failed to get cert: %s\n", gnupg_strerror (rc));
goto next_signer;
}
if (msgdigest)
{ /* Signed attributes are available. */
GCRY_MD_HD md;
unsigned char *s;
/* check that the message digest in the signed attributes
matches the one we calculated on the data */
s = gcry_md_read (data_md, algo);
if ( !s || !msgdigestlen
|| gcry_md_get_algo_dlen (algo) != msgdigestlen
|| !s || memcmp (s, msgdigest, msgdigestlen) )
{
log_error ("message digest attribute does not "
"match calculated one\n");
gpgsm_status (ctrl, STATUS_BADSIG, NULL);
goto next_signer;
}
md = gcry_md_open (algo, 0);
if (!md)
{
log_error ("md_open failed: %s\n", gcry_strerror (-1));
goto next_signer;
}
if (DBG_HASHING)
gcry_md_start_debug (md, "vrfy.attr");
ksba_cms_set_hash_function (cms, HASH_FNC, md);
rc = ksba_cms_hash_signed_attrs (cms, signer);
if (rc)
{
log_debug ("hashing signed attrs failed: %s\n",
ksba_strerror (rc));
gcry_md_close (md);
goto next_signer;
}
rc = gpgsm_check_cms_signature (cert, sigval, md, algo);
gcry_md_close (md);
}
else
{
rc = gpgsm_check_cms_signature (cert, sigval, data_md, algo);
}
if (rc)
{
log_error ("invalid signature: %s\n", gnupg_strerror (rc));
gpgsm_status (ctrl, STATUS_BADSIG, NULL);
goto next_signer;
}
log_debug ("signature okay - checking certs\n");
gpgsm_status (ctrl, STATUS_GOODSIG, NULL);
{
char *buf, *fpr, *tstr;
fpr = gpgsm_get_fingerprint_hexstring (cert, GCRY_MD_SHA1);
tstr = strtimestamp (sigtime);
buf = xmalloc ( strlen(fpr) + strlen (tstr) + 100);
sprintf (buf, "%s %s %lu", fpr, tstr, (unsigned long)sigtime );
xfree (tstr);
xfree (fpr);
gpgsm_status (ctrl, STATUS_VALIDSIG, buf);
xfree (buf);
}
rc = gpgsm_validate_path (cert);
if (rc)
{
log_error ("invalid certification path: %s\n", gnupg_strerror (rc));
if (rc == GNUPG_Bad_Certificate_Path
|| rc == GNUPG_Bad_Certificate)
gpgsm_status (ctrl, STATUS_TRUST_NEVER, NULL);
else
gpgsm_status (ctrl, STATUS_TRUST_UNDEFINED, NULL);
goto next_signer;
}
log_info ("signature is good\n");
gpgsm_status (ctrl, STATUS_TRUST_FULLY, NULL);
next_signer:
rc = 0;
xfree (issuer);
xfree (serial);
xfree (sigval);
xfree (msgdigest);
ksba_cert_release (cert);
cert = NULL;
}
rc = 0;
if (err)
{
log_debug ("ksba error: %s\n", ksba_strerror (err));
rc = map_ksba_err (rc);
}
leave:
ksba_cms_release (cms);
gpgsm_destroy_reader (b64reader);
keydb_release (kh);
gcry_md_close (data_md);
if (fp)
fclose (fp);
return rc;
}