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gnupg/sm/verify.c
Werner Koch b008274afd Nuked almost all trailing white space. 
We better do this once and for all instead of cluttering all future
commits with diffs of trailing white spaces.  In the majority of cases
blank or single lines are affected and thus this change won't disturb
a git blame too much.  For future commits the pre-commit scripts
checks that this won't happen again.
2011-02-04 12:57:53 +01:00

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/* verify.c - Verify a messages signature
* Copyright (C) 2001, 2002, 2003, 2007,
* 2010 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 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 <http://www.gnu.org/licenses/>.
*/
#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 (ksba_isotime_t atime)
{
char *buffer = xmalloc (15);
if (!atime || !*atime)
strcpy (buffer, "none");
else
sprintf (buffer, "%.4s-%.2s-%.2s", atime, atime+4, atime+6);
return buffer;
}
/* Hash the data for a detached signature. Returns 0 on success. */
static gpg_error_t
hash_data (int fd, gcry_md_hd_t md)
{
gpg_error_t err = 0;
estream_t fp;
char buffer[4096];
int nread;
fp = es_fdopen_nc (fd, "rb");
if (!fp)
{
err = gpg_error_from_syserror ();
log_error ("fdopen(%d) failed: %s\n", fd, gpg_strerror (err));
return err;
}
do
{
nread = es_fread (buffer, 1, DIM(buffer), fp);
gcry_md_write (md, buffer, nread);
}
while (nread);
if (es_ferror (fp))
{
err = gpg_error_from_syserror ();
log_error ("read error on fd %d: %s\n", fd, gpg_strerror (err));
}
es_fclose (fp);
return err;
}
/* 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_t ctrl, int in_fd, int data_fd, estream_t out_fp)
{
int i, rc;
Base64Context b64reader = NULL;
Base64Context b64writer = NULL;
ksba_reader_t reader;
ksba_writer_t writer = NULL;
ksba_cms_t cms = NULL;
ksba_stop_reason_t stopreason;
ksba_cert_t cert;
KEYDB_HANDLE kh;
gcry_md_hd_t data_md = NULL;
int signer;
const char *algoid;
int algo;
int is_detached;
estream_t in_fp = NULL;
char *p;
audit_set_type (ctrl->audit, AUDIT_TYPE_VERIFY);
kh = keydb_new (0);
if (!kh)
{
log_error (_("failed to allocated keyDB handle\n"));
rc = gpg_error (GPG_ERR_GENERAL);
goto leave;
}
in_fp = es_fdopen_nc (in_fd, "rb");
if (!in_fp)
{
rc = gpg_error_from_syserror ();
log_error ("fdopen() failed: %s\n", strerror (errno));
goto leave;
}
rc = gpgsm_create_reader (&b64reader, ctrl, in_fp, 0, &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;
}
}
rc = ksba_cms_new (&cms);
if (rc)
goto leave;
rc = ksba_cms_set_reader_writer (cms, reader, writer);
if (rc)
{
log_error ("ksba_cms_set_reader_writer failed: %s\n",
gpg_strerror (rc));
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");
audit_log (ctrl->audit, AUDIT_SETUP_READY);
is_detached = 0;
do
{
rc = ksba_cms_parse (cms, &stopreason);
if (rc)
{
log_error ("ksba_cms_parse failed: %s\n", gpg_strerror (rc));
goto leave;
}
if (stopreason == KSBA_SR_NEED_HASH)
{
is_detached = 1;
audit_log (ctrl->audit, AUDIT_DETACHED_SIGNATURE);
if (opt.verbose)
log_info ("detached signature\n");
}
if (stopreason == KSBA_SR_NEED_HASH
|| stopreason == KSBA_SR_BEGIN_DATA)
{
audit_log (ctrl->audit, AUDIT_GOT_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:"?");
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"));
audit_log_s (ctrl->audit, AUDIT_BAD_DATA_HASH_ALGO, algoid);
}
else
{
if (DBG_X509)
log_debug ("enabling hash algorithm %d (%s)\n",
algo, algoid? algoid:"");
gcry_md_enable (data_md, algo);
audit_log_i (ctrl->audit, AUDIT_DATA_HASH_ALGO, algo);
}
}
if (opt.extra_digest_algo)
{
if (DBG_X509)
log_debug ("enabling extra hash algorithm %d\n",
opt.extra_digest_algo);
gcry_md_enable (data_md, opt.extra_digest_algo);
audit_log_i (ctrl->audit, AUDIT_DATA_HASH_ALGO,
opt.extra_digest_algo);
}
if (is_detached)
{
if (data_fd == -1)
{
log_info ("detached signature w/o data "
"- assuming certs-only\n");
audit_log (ctrl->audit, AUDIT_CERT_ONLY_SIG);
}
else
audit_log_ok (ctrl->audit, AUDIT_DATA_HASHING,
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 */
audit_log_ok (ctrl->audit, AUDIT_DATA_HASHING, 0);
}
}
while (stopreason != KSBA_SR_READY);
if (b64writer)
{
rc = gpgsm_finish_writer (b64writer);
if (rc)
{
log_error ("write failed: %s\n", gpg_strerror (rc));
audit_log_ok (ctrl->audit, AUDIT_WRITE_ERROR, 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);
audit_log (ctrl->audit, AUDIT_USAGE_ERROR);
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. */
audit_log_cert (ctrl->audit, AUDIT_SAVE_CERT, cert,
keydb_store_cert (cert, 0, NULL));
ksba_cert_release (cert);
}
cert = NULL;
for (signer=0; ; signer++)
{
char *issuer = NULL;
ksba_sexp_t sigval = NULL;
ksba_isotime_t sigtime, keyexptime;
ksba_sexp_t serial;
char *msgdigest = NULL;
size_t msgdigestlen;
char *ctattr;
int sigval_hash_algo;
int info_pkalgo;
unsigned int verifyflags;
rc = ksba_cms_get_issuer_serial (cms, signer, &issuer, &serial);
if (!signer && gpg_err_code (rc) == GPG_ERR_NO_DATA
&& data_fd == -1 && is_detached)
{
log_info ("certs-only message accepted\n");
rc = 0;
break;
}
if (rc)
{
if (signer && rc == -1)
rc = 0;
break;
}
gpgsm_status (ctrl, STATUS_NEWSIG, NULL);
audit_log_i (ctrl->audit, AUDIT_NEW_SIG, signer);
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");
}
if (ctrl->audit)
{
char *tmpstr = gpgsm_format_sn_issuer (serial, issuer);
audit_log_s (ctrl->audit, AUDIT_SIG_NAME, tmpstr);
xfree (tmpstr);
}
rc = ksba_cms_get_signing_time (cms, signer, sigtime);
if (gpg_err_code (rc) == GPG_ERR_NO_DATA)
*sigtime = 0;
else if (rc)
{
log_error ("error getting signing time: %s\n", gpg_strerror (rc));
*sigtime = 0; /* (we can't encode an error in the time string.) */
}
rc = ksba_cms_get_message_digest (cms, signer,
&msgdigest, &msgdigestlen);
if (!rc)
{
size_t is_enabled;
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);
is_enabled = sizeof algo;
if ( gcry_md_info (data_md, GCRYCTL_IS_ALGO_ENABLED,
&algo, &is_enabled)
|| !is_enabled)
{
log_error ("digest algo %d (%s) has not been enabled\n",
algo, algoid?algoid:"");
audit_log_s (ctrl->audit, AUDIT_SIG_STATUS, "unsupported");
goto next_signer;
}
}
else if (gpg_err_code (rc) == GPG_ERR_NO_DATA)
{
assert (!msgdigest);
rc = 0;
algoid = NULL;
algo = 0;
}
else /* real error */
{
audit_log_s (ctrl->audit, AUDIT_SIG_STATUS, "error");
break;
}
rc = ksba_cms_get_sigattr_oids (cms, signer,
"1.2.840.113549.1.9.3", &ctattr);
if (!rc)
{
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;
audit_log_s (ctrl->audit, AUDIT_SIG_STATUS, "bad");
goto next_signer;
}
ksba_free (ctattr);
ctattr = NULL;
}
else if (rc != -1)
{
log_error ("error getting content-type attribute: %s\n",
gpg_strerror (rc));
audit_log_s (ctrl->audit, AUDIT_SIG_STATUS, "bad");
goto next_signer;
}
rc = 0;
sigval = ksba_cms_get_sig_val (cms, signer);
if (!sigval)
{
log_error ("no signature value available\n");
audit_log_s (ctrl->audit, AUDIT_SIG_STATUS, "bad");
goto next_signer;
}
sigval_hash_algo = hash_algo_from_sigval (sigval);
if (DBG_X509)
{
log_debug ("signer %d - signature available (sigval hash=%d)",
signer, sigval_hash_algo);
/* log_printhex ("sigval ", sigval, */
/* gcry_sexp_canon_len (sigval, 0, NULL, NULL)); */
}
if (!sigval_hash_algo)
sigval_hash_algo = algo; /* Fallback used e.g. with old libksba. */
/* 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);
}
audit_log_s (ctrl->audit, AUDIT_SIG_STATUS, "no-cert");
goto next_signer;
}
rc = keydb_get_cert (kh, &cert);
if (rc)
{
log_error ("failed to get cert: %s\n", gpg_strerror (rc));
audit_log_s (ctrl->audit, AUDIT_SIG_STATUS, "error");
goto next_signer;
}
log_info (_("Signature made "));
if (*sigtime)
dump_isotime (sigtime);
else
log_printf (_("[date not given]"));
log_printf (_(" using certificate ID 0x%08lX\n"),
gpgsm_get_short_fingerprint (cert, NULL));
audit_log_i (ctrl->audit, AUDIT_DATA_HASH_ALGO, algo);
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 computed one\n"));
if (DBG_X509)
{
if (msgdigest)
log_printhex ("message: ", msgdigest, msgdigestlen);
if (s)
log_printhex ("computed: ",
s, gcry_md_get_algo_dlen (algo));
}
fpr = gpgsm_fpr_and_name_for_status (cert);
gpgsm_status (ctrl, STATUS_BADSIG, fpr);
xfree (fpr);
audit_log_s (ctrl->audit, AUDIT_SIG_STATUS, "bad");
goto next_signer;
}
audit_log_i (ctrl->audit, AUDIT_ATTR_HASH_ALGO, sigval_hash_algo);
rc = gcry_md_open (&md, sigval_hash_algo, 0);
if (rc)
{
log_error ("md_open failed: %s\n", gpg_strerror (rc));
audit_log_s (ctrl->audit, AUDIT_SIG_STATUS, "error");
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",
gpg_strerror (rc));
gcry_md_close (md);
audit_log_s (ctrl->audit, AUDIT_SIG_STATUS, "error");
goto next_signer;
}
rc = gpgsm_check_cms_signature (cert, sigval, md,
sigval_hash_algo, &info_pkalgo);
gcry_md_close (md);
}
else
{
rc = gpgsm_check_cms_signature (cert, sigval, data_md,
algo, &info_pkalgo);
}
if (rc)
{
char *fpr;
log_error ("invalid signature: %s\n", gpg_strerror (rc));
fpr = gpgsm_fpr_and_name_for_status (cert);
gpgsm_status (ctrl, STATUS_BADSIG, fpr);
xfree (fpr);
audit_log_s (ctrl->audit, AUDIT_SIG_STATUS, "bad");
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");
audit_log (ctrl->audit, AUDIT_VALIDATE_CHAIN);
rc = gpgsm_validate_chain (ctrl, cert,
*sigtime? sigtime : "19700101T000000",
keyexptime, 0,
NULL, 0, &verifyflags);
{
char *fpr, *buf, *tstr;
fpr = gpgsm_fpr_and_name_for_status (cert);
if (gpg_err_code (rc) == GPG_ERR_CERT_EXPIRED)
{
gpgsm_status (ctrl, STATUS_EXPKEYSIG, fpr);
rc = 0;
}
else
gpgsm_status (ctrl, STATUS_GOODSIG, fpr);
xfree (fpr);
fpr = gpgsm_get_fingerprint_hexstring (cert, GCRY_MD_SHA1);
tstr = strtimestamp_r (sigtime);
buf = xasprintf ("%s %s %s %s 0 0 %d %d 00", fpr, tstr,
*sigtime? sigtime : "0",
*keyexptime? keyexptime : "0",
info_pkalgo, algo);
xfree (tstr);
xfree (fpr);
gpgsm_status (ctrl, STATUS_VALIDSIG, buf);
xfree (buf);
}
audit_log_ok (ctrl->audit, AUDIT_CHAIN_STATUS, rc);
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));
audit_log_s (ctrl->audit, AUDIT_SIG_STATUS, "bad");
goto next_signer;
}
audit_log_s (ctrl->audit, AUDIT_SIG_STATUS, "good");
for (i=0; (p = ksba_cert_get_subject (cert, i)); i++)
{
log_info (!i? _("Good signature from")
: _(" aka"));
log_printf (" \"");
gpgsm_es_print_name (log_get_stream (), p);
log_printf ("\"\n");
ksba_free (p);
}
/* Print a note if this is a qualified signature. */
{
size_t qualbuflen;
char qualbuffer[1];
rc = ksba_cert_get_user_data (cert, "is_qualified", &qualbuffer,
sizeof (qualbuffer), &qualbuflen);
if (!rc && qualbuflen)
{
if (*qualbuffer)
{
log_info (_("This is a qualified signature\n"));
if (!opt.qualsig_approval)
log_info
(_("Note, that this software is not officially approved "
"to create or verify such signatures.\n"));
}
}
else if (gpg_err_code (rc) != GPG_ERR_NOT_FOUND)
log_error ("get_user_data(is_qualified) failed: %s\n",
gpg_strerror (rc));
}
gpgsm_status (ctrl, STATUS_TRUST_FULLY,
(verifyflags & VALIDATE_FLAG_CHAIN_MODEL)?
"0 chain": "0 shell");
next_signer:
rc = 0;
xfree (issuer);
xfree (serial);
xfree (sigval);
xfree (msgdigest);
ksba_cert_release (cert);
cert = NULL;
}
rc = 0;
leave:
ksba_cms_release (cms);
gpgsm_destroy_reader (b64reader);
gpgsm_destroy_writer (b64writer);
keydb_release (kh);
gcry_md_close (data_md);
es_fclose (in_fp);
if (rc)
{
char numbuf[50];
sprintf (numbuf, "%d", rc );
gpgsm_status2 (ctrl, STATUS_ERROR, "verify.leave",
numbuf, NULL);
}
return rc;
}
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