/* verify.c - Verify a messages signature
* Copyright (C) 2001, 2002, 2003 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 "gpgsm.h"
#include <gcrypt.h>
#include <ksba.h>
#include "keydb.h"
#include "i18n.h"
static char *
strtimestamp_r (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;
}
/* Hash the data for a detached signature */
static void
hash_data (int fd, gcry_md_hd_t 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. With OUT_FP given and a non-detached
signature, the signed material is written to that stream. */
int
gpgsm_verify (CTRL ctrl, int in_fd, int data_fd, FILE *out_fp)
{
int i, rc;
Base64Context b64reader = NULL;
Base64Context b64writer = NULL;
KsbaError err;
KsbaReader reader;
KsbaWriter writer = NULL;
KsbaCMS cms = NULL;
KsbaStopReason stopreason;
KsbaCert cert;
KEYDB_HANDLE kh;
gcry_md_hd_t data_md = NULL;
int signer;
const char *algoid;
int algo;
int is_detached;
FILE *fp = NULL;
char *p;
kh = keydb_new (0);
if (!kh)
{
log_error (_("failed to allocated keyDB handle\n"));
rc = gpg_error (GPG_ERR_GENERAL);
goto leave;
}
fp = fdopen ( dup (in_fd), "rb");
if (!fp)
{
rc = gpg_error (gpg_err_code_from_errno (errno));
log_error ("fdopen() failed: %s\n", strerror (errno));
goto leave;
}
rc = gpgsm_create_reader (&b64reader, ctrl, fp, &reader);
if (rc)
{
log_error ("can't create reader: %s\n", gpg_strerror (rc));
goto leave;
}
if (out_fp)
{
rc = gpgsm_create_writer (&b64writer, ctrl, out_fp, &writer);
if (rc)
{
log_error ("can't create writer: %s\n", gpg_strerror (rc));
goto leave;
}
}
cms = ksba_cms_new ();
if (!cms)
{
rc = gpg_error (GPG_ERR_ENOMEM);
goto leave;
}
err = ksba_cms_set_reader_writer (cms, reader, writer);
if (err)
{
log_error ("ksba_cms_set_reader_writer failed: %s\n",
ksba_strerror (err));
rc = map_ksba_err (err);
goto leave;
}
rc = gcry_md_open (&data_md, 0, 0);
if (rc)
{
log_error ("md_open failed: %s\n", gpg_strerror (rc));
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_error ("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;
if (opt.verbose)
log_info ("detached signature\n");
}
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_info ("detached signature w/o data "
"- assuming certs-only\n");
else
hash_data (data_fd, data_md);
}
else
{
ksba_cms_set_hash_function (cms, HASH_FNC, data_md);
}
}
else if (stopreason == KSBA_SR_END_DATA)
{ /* The data bas been hashed */
}
}
while (stopreason != KSBA_SR_READY);
if (b64writer)
{
rc = gpgsm_finish_writer (b64writer);
if (rc)
{
log_error ("write failed: %s\n", gpg_strerror (rc));
goto leave;
}
}
if (data_fd != -1 && !is_detached)
{
log_error ("data given for a non-detached signature\n");
rc = gpg_error (GPG_ERR_CONFLICT);
goto leave;
}
for (i=0; (cert=ksba_cms_get_cert (cms, i)); i++)
{
/* Fixme: it might be better to check the validity of the
certificate first before entering it into the DB. This way
we would avoid cluttering the DB with invalid
certificates. */
keydb_store_cert (cert, 0, NULL);
ksba_cert_release (cert);
}
cert = NULL;
err = 0;
for (signer=0; ; signer++)
{
char *issuer = NULL;
KsbaSexp sigval = NULL;
time_t sigtime, keyexptime;
KsbaSexp serial;
char *msgdigest = NULL;
size_t msgdigestlen;
char *ctattr;
err = ksba_cms_get_issuer_serial (cms, signer, &issuer, &serial);
if (!signer && err == KSBA_No_Data && data_fd == -1 && is_detached)
{
log_info ("certs-only message accepted\n");
err = 0;
break;
}
if (err)
{
if (signer && err == -1)
err = 0;
break;
}
if (DBG_X509)
{
log_debug ("signer %d - issuer: `%s'\n",
signer, issuer? issuer:"[NONE]");
log_debug ("signer %d - serial: ", signer);
gpgsm_dump_serial (serial);
log_printf ("\n");
}
err = ksba_cms_get_signing_time (cms, signer, &sigtime);
if (err == KSBA_No_Data)
sigtime = 0;
else if (err)
{
log_error ("error getting signing time: %s\n", ksba_strerror (err));
sigtime = (time_t)-1;
}
err = ksba_cms_get_message_digest (cms, signer,
&msgdigest, &msgdigestlen);
if (!err)
{
algoid = ksba_cms_get_digest_algo (cms, signer);
algo = gcry_md_map_name (algoid);
if (DBG_X509)
log_debug ("signer %d - digest algo: %d\n", signer, algo);
if ( !gcry_md_info (data_md, GCRYCTL_IS_ALGO_ENABLED, &algo, NULL) )
{
log_error ("digest algo %d has not been enabled\n", algo);
goto next_signer;
}
}
else if (err == KSBA_No_Data)
{
assert (!msgdigest);
err = 0;
algoid = NULL;
algo = 0;
}
else /* real error */
break;
err = ksba_cms_get_sigattr_oids (cms, signer,
"1.2.840.113549.1.9.3",&ctattr);
if (!err)
{
const char *s;
if (DBG_X509)
log_debug ("signer %d - content-type attribute: %s", signer, ctattr);
s = ksba_cms_get_content_oid (cms, 1);
if (!s || strcmp (ctattr, s))
{
log_error ("content-type attribute does not match "
"actual content-type\n");
ksba_free (ctattr);
ctattr = NULL;
goto next_signer;
}
ksba_free (ctattr);
ctattr = NULL;
}
else if (err != -1)
{
log_error ("error getting content-type attribute: %s\n",
ksba_strerror (err));
goto next_signer;
}
err = 0;
sigval = ksba_cms_get_sig_val (cms, signer);
if (!sigval)
{
log_error ("no signature value available\n");
goto next_signer;
}
if (DBG_X509)
log_debug ("signer %d - signature available", signer);
/* Find the certificate of the signer */
keydb_search_reset (kh);
rc = keydb_search_issuer_sn (kh, issuer, serial);
if (rc)
{
if (rc == -1)
{
log_error ("certificate not found\n");
rc = gpg_error (GPG_ERR_NO_PUBKEY);
}
else
log_error ("failed to find the certificate: %s\n",
gpg_strerror(rc));
{
char numbuf[50];
sprintf (numbuf, "%d", rc);
gpgsm_status2 (ctrl, STATUS_ERROR, "verify.findkey",
numbuf, NULL);
}
/* fixme: we might want to append the issuer and serial
using our standard notation */
goto next_signer;
}
rc = keydb_get_cert (kh, &cert);
if (rc)
{
log_error ("failed to get cert: %s\n", gpg_strerror (rc));
goto next_signer;
}
log_info (_("Signature made "));
if (sigtime)
gpgsm_dump_time (sigtime);
else
log_printf (_("[date not given]"));
log_printf (_(" using certificate ID %08lX\n"),
gpgsm_get_short_fingerprint (cert));
if (msgdigest)
{ /* Signed attributes are available. */
gcry_md_hd_t 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) )
{
char *fpr;
log_error ("invalid signature: message digest attribute "
"does not match calculated one\n");
fpr = gpgsm_get_fingerprint_hexstring (cert, GCRY_MD_SHA1);
gpgsm_status (ctrl, STATUS_BADSIG, fpr);
xfree (fpr);
goto next_signer;
}
rc = gcry_md_open (&md, algo, 0);
if (rc)
{
log_error ("md_open failed: %s\n", gpg_strerror (rc));
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_error ("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)
{
char *fpr;
log_error ("invalid signature: %s\n", gpg_strerror (rc));
fpr = gpgsm_get_fingerprint_hexstring (cert, GCRY_MD_SHA1);
gpgsm_status (ctrl, STATUS_BADSIG, fpr);
xfree (fpr);
goto next_signer;
}
rc = gpgsm_cert_use_verify_p (cert); /*(this displays an info message)*/
if (rc)
{
gpgsm_status_with_err_code (ctrl, STATUS_ERROR, "verify.keyusage",
gpg_err_code (rc));
rc = 0;
}
if (DBG_X509)
log_debug ("signature okay - checking certs\n");
rc = gpgsm_validate_chain (ctrl, cert, &keyexptime);
if (gpg_err_code (rc) == GPG_ERR_CERT_EXPIRED)
{
gpgsm_status (ctrl, STATUS_EXPKEYSIG, NULL);
rc = 0;
}
else
gpgsm_status (ctrl, STATUS_GOODSIG, NULL);
{
char *buf, *fpr, *tstr;
fpr = gpgsm_get_fingerprint_hexstring (cert, GCRY_MD_SHA1);
tstr = strtimestamp_r (sigtime);
buf = xmalloc ( strlen(fpr) + strlen (tstr) + 120);
sprintf (buf, "%s %s %lu %lu", fpr, tstr,
(unsigned long)sigtime, (unsigned long)keyexptime );
xfree (tstr);
xfree (fpr);
gpgsm_status (ctrl, STATUS_VALIDSIG, buf);
xfree (buf);
}
if (rc) /* of validate_chain */
{
log_error ("invalid certification chain: %s\n", gpg_strerror (rc));
if (gpg_err_code (rc) == GPG_ERR_BAD_CERT_CHAIN
|| gpg_err_code (rc) == GPG_ERR_BAD_CERT
|| gpg_err_code (rc) == GPG_ERR_BAD_CA_CERT
|| gpg_err_code (rc) == GPG_ERR_CERT_REVOKED)
gpgsm_status_with_err_code (ctrl, STATUS_TRUST_NEVER, NULL,
gpg_err_code (rc));
else
gpgsm_status_with_err_code (ctrl, STATUS_TRUST_UNDEFINED, NULL,
gpg_err_code (rc));
goto next_signer;
}
for (i=0; (p = ksba_cert_get_subject (cert, i)); i++)
{
log_info (!i? _("Good signature from")
: _(" aka"));
log_printf (" \"");
gpgsm_print_name (log_get_stream (), p);
log_printf ("\"\n");
ksba_free (p);
}
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_error ("ksba error: %s\n", ksba_strerror (err));
rc = map_ksba_err (rc);
}
leave:
ksba_cms_release (cms);
gpgsm_destroy_reader (b64reader);
gpgsm_destroy_writer (b64writer);
keydb_release (kh);
gcry_md_close (data_md);
if (fp)
fclose (fp);
if (rc)
{
char numbuf[50];
sprintf (numbuf, "%d", rc );
gpgsm_status2 (ctrl, STATUS_ERROR, "verify.leave",
numbuf, NULL);
}
return rc;
}