/* sign.c - Sign a message
* 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
* 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 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);
}
static int
hash_and_copy_data (int fd, gcry_md_hd_t md, ksba_writer_t writer)
{
gpg_error_t err;
FILE *fp;
char buffer[4096];
int nread;
int rc = 0;
int any = 0;
fp = fdopen ( dup (fd), "rb");
if (!fp)
{
gpg_error_t tmperr = gpg_error (gpg_err_code_from_errno (errno));
log_error ("fdopen(%d) failed: %s\n", fd, strerror (errno));
return tmperr;
}
do
{
nread = fread (buffer, 1, DIM(buffer), fp);
if (nread)
{
any = 1;
gcry_md_write (md, buffer, nread);
err = ksba_writer_write_octet_string (writer, buffer, nread, 0);
if (err)
{
log_error ("write failed: %s\n", gpg_strerror (err));
rc = err;
}
}
}
while (nread && !rc);
if (ferror (fp))
{
rc = gpg_error (gpg_err_code_from_errno (errno));
log_error ("read error on fd %d: %s\n", fd, strerror (errno));
}
fclose (fp);
if (!any)
{
/* We can't allow to sign an empty message because it does not
make much sense and more seriously, ksba-cms_build has
already written the tag for data and now expects an octet
string but an octet string of zeize 0 is illegal. */
log_error ("cannot sign an empty message\n");
rc = gpg_error (GPG_ERR_NO_DATA);
}
if (!rc)
{
err = ksba_writer_write_octet_string (writer, NULL, 0, 1);
if (err)
{
log_error ("write failed: %s\n", gpg_strerror (err));
rc = err;
}
}
return rc;
}
/* Get the default certificate which is defined as the first cabable
of signing our keyDB returns and has a secret key available. */
int
gpgsm_get_default_cert (ctrl_t ctrl, ksba_cert_t *r_cert)
{
KEYDB_HANDLE hd;
ksba_cert_t cert = NULL;
int rc;
char *p;
hd = keydb_new (0);
if (!hd)
return gpg_error (GPG_ERR_GENERAL);
rc = keydb_search_first (hd);
if (rc)
{
keydb_release (hd);
return rc;
}
do
{
rc = keydb_get_cert (hd, &cert);
if (rc)
{
log_error ("keydb_get_cert failed: %s\n", gpg_strerror (rc));
keydb_release (hd);
return rc;
}
if (!gpgsm_cert_use_sign_p (cert))
{
p = gpgsm_get_keygrip_hexstring (cert);
if (p)
{
if (!gpgsm_agent_havekey (ctrl, p))
{
xfree (p);
keydb_release (hd);
*r_cert = cert;
return 0; /* got it */
}
xfree (p);
}
}
ksba_cert_release (cert);
cert = NULL;
}
while (!(rc = keydb_search_next (hd)));
if (rc && rc != -1)
log_error ("keydb_search_next failed: %s\n", gpg_strerror (rc));
ksba_cert_release (cert);
keydb_release (hd);
return rc;
}
static ksba_cert_t
get_default_signer (ctrl_t ctrl)
{
KEYDB_SEARCH_DESC desc;
ksba_cert_t cert = NULL;
KEYDB_HANDLE kh = NULL;
int rc;
if (!opt.local_user)
{
rc = gpgsm_get_default_cert (ctrl, &cert);
if (rc)
{
if (rc != -1)
log_debug ("failed to find default certificate: %s\n",
gpg_strerror (rc));
return NULL;
}
return cert;
}
rc = keydb_classify_name (opt.local_user, &desc);
if (rc)
{
log_error ("failed to find default signer: %s\n", gpg_strerror (rc));
return NULL;
}
kh = keydb_new (0);
if (!kh)
return NULL;
rc = keydb_search (kh, &desc, 1);
if (rc)
{
log_debug ("failed to find default certificate: rc=%d\n", rc);
}
else
{
rc = keydb_get_cert (kh, &cert);
if (rc)
{
log_debug ("failed to get cert: rc=%d\n", rc);
}
}
keydb_release (kh);
return cert;
}
/* Depending on the options in CTRL add the certificate CERT as well as
other certificate up in the chain to the Root-CA to the CMS
object. */
static int
add_certificate_list (ctrl_t ctrl, ksba_cms_t cms, ksba_cert_t cert)
{
gpg_error_t err;
int rc = 0;
ksba_cert_t next = NULL;
int n;
int not_root = 0;
ksba_cert_ref (cert);
n = ctrl->include_certs;
log_debug ("adding certificates at level %d\n", n);
if (n == -2)
{
not_root = 1;
n = -1;
}
if (n < 0 || n > 50)
n = 50; /* We better apply an upper bound */
/* First add my own certificate unless we don't want any certificate
included at all. */
if (n)
{
if (not_root && gpgsm_is_root_cert (cert))
err = 0;
else
err = ksba_cms_add_cert (cms, cert);
if (err)
goto ksba_failure;
if (n>0)
n--;
}
/* Walk the chain to include all other certificates. Note that a -1
used for N makes sure that there is no limit and all certs get
included. */
while ( n-- && !(rc = gpgsm_walk_cert_chain (cert, &next)) )
{
if (not_root && gpgsm_is_root_cert (next))
err = 0;
else
err = ksba_cms_add_cert (cms, next);
ksba_cert_release (cert);
cert = next; next = NULL;
if (err)
goto ksba_failure;
}
ksba_cert_release (cert);
return rc == -1? 0: rc;
ksba_failure:
ksba_cert_release (cert);
log_error ("ksba_cms_add_cert failed: %s\n", gpg_strerror (err));
return err;
}
/* Perform a sign operation.
Sign the data received on DATA-FD in embedded mode or in detached
mode when DETACHED is true. Write the signature to OUT_FP. The
keys used to sign are taken from SIGNERLIST or the default one will
be used if the value of this argument is NULL. */
int
gpgsm_sign (ctrl_t ctrl, certlist_t signerlist,
int data_fd, int detached, FILE *out_fp)
{
int i, rc;
gpg_error_t err;
Base64Context b64writer = NULL;
ksba_writer_t writer;
ksba_cms_t cms = NULL;
ksba_stop_reason_t stopreason;
KEYDB_HANDLE kh = NULL;
gcry_md_hd_t data_md = NULL;
int signer;
const char *algoid;
int algo;
ksba_isotime_t signed_at;
certlist_t cl;
int release_signerlist = 0;
kh = keydb_new (0);
if (!kh)
{
log_error (_("failed to allocated keyDB handle\n"));
rc = gpg_error (GPG_ERR_GENERAL);
goto leave;
}
ctrl->pem_name = "SIGNED MESSAGE";
rc = gpgsm_create_writer (&b64writer, ctrl, out_fp, NULL, &writer);
if (rc)
{
log_error ("can't create writer: %s\n", gpg_strerror (rc));
goto leave;
}
err = ksba_cms_new (&cms);
if (err)
{
rc = err;
goto leave;
}
err = ksba_cms_set_reader_writer (cms, NULL, writer);
if (err)
{
log_debug ("ksba_cms_set_reader_writer failed: %s\n",
gpg_strerror (err));
rc = err;
goto leave;
}
/* We are going to create signed data with data as encap. content */
err = ksba_cms_set_content_type (cms, 0, KSBA_CT_SIGNED_DATA);
if (!err)
err = ksba_cms_set_content_type (cms, 1, KSBA_CT_DATA);
if (err)
{
log_debug ("ksba_cms_set_content_type failed: %s\n",
gpg_strerror (err));
rc = err;
goto leave;
}
/* If no list of signers is given, use a default one. */
if (!signerlist)
{
ksba_cert_t cert = get_default_signer (ctrl);
if (!cert)
{
log_error ("no default signer found\n");
rc = gpg_error (GPG_ERR_GENERAL);
goto leave;
}
/* Although we don't check for ambigious specification we will
check that the signer's certificate is is usable and
valid. */
rc = gpgsm_cert_use_sign_p (cert);
if (!rc)
rc = gpgsm_validate_chain (ctrl, cert, NULL, 0, NULL, 0);
if (rc)
goto leave;
/* That one is fine - create signerlist. */
signerlist = xtrycalloc (1, sizeof *signerlist);
if (!signerlist)
{
rc = out_of_core ();
ksba_cert_release (cert);
goto leave;
}
signerlist->cert = cert;
release_signerlist = 1;
}
/* Gather certificates of signers and store them in the CMS object. */
for (cl=signerlist; cl; cl = cl->next)
{
rc = gpgsm_cert_use_sign_p (cl->cert);
if (rc)
goto leave;
err = ksba_cms_add_signer (cms, cl->cert);
if (err)
{
log_error ("ksba_cms_add_signer failed: %s\n", gpg_strerror (err));
rc = err;
goto leave;
}
rc = add_certificate_list (ctrl, cms, cl->cert);
if (rc)
{
log_error ("failed to store list of certificates: %s\n",
gpg_strerror(rc));
goto leave;
}
/* Set the hash algorithm we are going to use */
err = ksba_cms_add_digest_algo (cms, "1.3.14.3.2.26" /*SHA-1*/);
if (err)
{
log_debug ("ksba_cms_add_digest_algo failed: %s\n",
gpg_strerror (err));
rc = err;
goto leave;
}
}
/* Check whether one of the certificates is qualified. Note that we
already validated the certificate and thus the user data stored
flag must be available. */
for (cl=signerlist; cl; cl = cl->next)
{
size_t buflen;
char buffer[1];
err = ksba_cert_get_user_data (cl->cert, "is_qualified",
&buffer, sizeof (buffer), &buflen);
if (err || !buflen)
{
log_error (_("checking for qualified certificate failed: %s\n"),
gpg_strerror (err));
rc = err;
goto leave;
}
if (*buffer)
err = gpgsm_qualified_consent (ctrl, cl->cert);
else
err = gpgsm_not_qualified_warning (ctrl, cl->cert);
if (err)
{
rc = err;
goto leave;
}
}
/* Prepare hashing (actually we are figuring out what we have set above)*/
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, "sign.data");
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:"?");
if (algoid
&& ( !strcmp (algoid, "1.2.840.113549.1.1.2")
||!strcmp (algoid, "1.2.840.113549.2.2")))
log_info (_("(this is the MD2 algorithm)\n"));
rc = gpg_error (GPG_ERR_BUG);
goto leave;
}
gcry_md_enable (data_md, algo);
}
if (detached)
{ /* we hash the data right now so that we can store the message
digest. ksba_cms_build() takes this as an flag that detached
data is expected. */
unsigned char *digest;
size_t digest_len;
/* Fixme do this for all signers and get the algo to use from
the signer's certificate - does not make mich sense, but we
should do this consistent as we have already done it above. */
algo = GCRY_MD_SHA1;
hash_data (data_fd, data_md);
digest = gcry_md_read (data_md, algo);
digest_len = gcry_md_get_algo_dlen (algo);
if ( !digest || !digest_len)
{
log_error ("problem getting the hash of the data\n");
rc = gpg_error (GPG_ERR_BUG);
goto leave;
}
for (cl=signerlist,signer=0; cl; cl = cl->next, signer++)
{
err = ksba_cms_set_message_digest (cms, signer, digest, digest_len);
if (err)
{
log_error ("ksba_cms_set_message_digest failed: %s\n",
gpg_strerror (err));
rc = err;
goto leave;
}
}
}
gnupg_get_isotime (signed_at);
for (cl=signerlist,signer=0; cl; cl = cl->next, signer++)
{
err = ksba_cms_set_signing_time (cms, signer, signed_at);
if (err)
{
log_error ("ksba_cms_set_signing_time failed: %s\n",
gpg_strerror (err));
rc = err;
goto leave;
}
}
/* We need to write at least a minimal list of our capabilities to
try to convince some MUAs to use 3DEs and not the crippled
RC2. Our list is:
aes128-CBC
des-EDE3-CBC
*/
err = ksba_cms_add_smime_capability (cms, "2.16.840.1.101.3.4.1.2", NULL, 0);
if (!err)
err = ksba_cms_add_smime_capability (cms, "1.2.840.113549.3.7", NULL, 0);
if (err)
{
log_error ("ksba_cms_add_smime_capability failed: %s\n",
gpg_strerror (err));
goto leave;
}
/* Main building loop. */
do
{
err = ksba_cms_build (cms, &stopreason);
if (err)
{
log_debug ("ksba_cms_build failed: %s\n", gpg_strerror (err));
rc = err;
goto leave;
}
if (stopreason == KSBA_SR_BEGIN_DATA)
{ /* hash the data and store the message digest */
unsigned char *digest;
size_t digest_len;
assert (!detached);
/* Fixme: get the algo to use from the signer's certificate
- does not make much sense, but we should do this
consistent as we have already done it above. Code is
mostly duplicated above. */
algo = GCRY_MD_SHA1;
rc = hash_and_copy_data (data_fd, data_md, writer);
if (rc)
goto leave;
digest = gcry_md_read (data_md, algo);
digest_len = gcry_md_get_algo_dlen (algo);
if ( !digest || !digest_len)
{
log_error ("problem getting the hash of the data\n");
rc = gpg_error (GPG_ERR_BUG);
goto leave;
}
for (cl=signerlist,signer=0; cl; cl = cl->next, signer++)
{
err = ksba_cms_set_message_digest (cms, signer,
digest, digest_len);
if (err)
{
log_error ("ksba_cms_set_message_digest failed: %s\n",
gpg_strerror (err));
rc = err;
goto leave;
}
}
}
else if (stopreason == KSBA_SR_NEED_SIG)
{ /* calculate the signature for all signers */
gcry_md_hd_t md;
algo = GCRY_MD_SHA1;
rc = gcry_md_open (&md, algo, 0);
if (rc)
{
log_error ("md_open failed: %s\n", gpg_strerror (rc));
goto leave;
}
if (DBG_HASHING)
gcry_md_start_debug (md, "sign.attr");
ksba_cms_set_hash_function (cms, HASH_FNC, md);
for (cl=signerlist,signer=0; cl; cl = cl->next, signer++)
{
unsigned char *sigval = NULL;
char *buf, *fpr;
if (signer)
gcry_md_reset (md);
rc = ksba_cms_hash_signed_attrs (cms, signer);
if (rc)
{
log_debug ("hashing signed attrs failed: %s\n",
gpg_strerror (rc));
gcry_md_close (md);
goto leave;
}
rc = gpgsm_create_cms_signature (ctrl, cl->cert,
md, algo, &sigval);
if (rc)
{
gcry_md_close (md);
goto leave;
}
err = ksba_cms_set_sig_val (cms, signer, sigval);
xfree (sigval);
if (err)
{
log_error ("failed to store the signature: %s\n",
gpg_strerror (err));
rc = err;
gcry_md_close (md);
goto leave;
}
/* write a status message */
fpr = gpgsm_get_fingerprint_hexstring (cl->cert, GCRY_MD_SHA1);
if (!fpr)
{
rc = gpg_error (GPG_ERR_ENOMEM);
gcry_md_close (md);
goto leave;
}
{
int pkalgo = gpgsm_get_key_algo_info (cl->cert, NULL);
rc = asprintf (&buf, "%c %d %d 00 %s %s",
detached? 'D':'S',
pkalgo,
algo,
signed_at,
fpr);
}
xfree (fpr);
if (rc < 0)
{
rc = gpg_error (GPG_ERR_ENOMEM);
gcry_md_close (md);
goto leave;
}
rc = 0;
gpgsm_status (ctrl, STATUS_SIG_CREATED, buf);
free (buf); /* yes, we must use the regular free() here */
}
gcry_md_close (md);
}
}
while (stopreason != KSBA_SR_READY);
rc = gpgsm_finish_writer (b64writer);
if (rc)
{
log_error ("write failed: %s\n", gpg_strerror (rc));
goto leave;
}
log_info ("signature created\n");
leave:
if (rc)
log_error ("error creating signature: %s <%s>\n",
gpg_strerror (rc), gpg_strsource (rc) );
if (release_signerlist)
gpgsm_release_certlist (signerlist);
ksba_cms_release (cms);
gpgsm_destroy_writer (b64writer);
keydb_release (kh);
gcry_md_close (data_md);
return rc;
}