mirror of
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640 lines
17 KiB
C
640 lines
17 KiB
C
/* certpath.c - path validation
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* Copyright (C) 2001 Free Software Foundation, Inc.
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*
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* This file is part of GnuPG.
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*
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* GnuPG is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* GnuPG is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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*/
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#include <config.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <errno.h>
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#include <unistd.h>
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#include <time.h>
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#include <assert.h>
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#include <gcrypt.h>
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#include <ksba.h>
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#include "gpgsm.h"
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#include "keydb.h"
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#include "i18n.h"
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static int
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unknown_criticals (KsbaCert cert)
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{
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static const char *known[] = {
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"2.5.29.15", /* keyUsage */
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"2.5.29.19", /* basic Constraints */
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"2.5.29.32", /* certificatePolicies */
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NULL
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};
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int rc = 0, i, idx, crit;
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const char *oid;
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KsbaError err;
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for (idx=0; !(err=ksba_cert_get_extension (cert, idx,
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&oid, &crit, NULL, NULL));idx++)
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{
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if (!crit)
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continue;
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for (i=0; known[i] && strcmp (known[i],oid); i++)
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;
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if (!known[i])
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{
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log_error (_("critical certificate extension %s is not supported\n"),
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oid);
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rc = GNUPG_Unsupported_Certificate;
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}
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}
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if (err && err != -1)
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rc = map_ksba_err (err);
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return rc;
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}
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static int
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allowed_ca (KsbaCert cert, int *pathlen)
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{
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KsbaError err;
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int flag;
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err = ksba_cert_is_ca (cert, &flag, pathlen);
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if (err)
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return map_ksba_err (err);
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if (!flag)
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{
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log_error (_("issuer certificate is not marked as a CA\n"));
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return GNUPG_Bad_CA_Certificate;
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}
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return 0;
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}
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static int
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check_cert_policy (KsbaCert cert)
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{
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KsbaError err;
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char *policies;
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FILE *fp;
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int any_critical;
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err = ksba_cert_get_cert_policies (cert, &policies);
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if (err == KSBA_No_Data)
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return 0; /* no policy given */
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if (err)
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return map_ksba_err (err);
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/* STRING is a line delimited list of certifiate policies as stored
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in the certificate. The line itself is colon delimited where the
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first field is the OID of the policy and the second field either
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N or C for normal or critical extension */
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if (opt.verbose > 1)
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log_info ("certificate's policy list: %s\n", policies);
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/* The check is very minimal but won't give false positives */
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any_critical = !!strstr (policies, ":C");
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if (!opt.policy_file)
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{
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xfree (policies);
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if (any_critical)
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{
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log_error ("critical marked policy without configured policies\n");
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return GNUPG_No_Policy_Match;
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}
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return 0;
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}
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fp = fopen (opt.policy_file, "r");
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if (!fp)
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{
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log_error ("failed to open `%s': %s\n",
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opt.policy_file, strerror (errno));
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xfree (policies);
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return GNUPG_Configuration_Error;
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}
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for (;;)
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{
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int c;
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char *p, line[256];
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char *haystack, *allowed;
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/* read line */
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do
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{
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if (!fgets (line, DIM(line)-1, fp) )
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{
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xfree (policies);
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if (feof (fp))
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{
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fclose (fp);
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log_error (_("certificate policy not allowed\n"));
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/* with no critical policies this is only a warning */
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return any_critical? GNUPG_No_Policy_Match : 0;
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}
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fclose (fp);
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return GNUPG_Read_Error;
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}
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if (!*line || line[strlen(line)-1] != '\n')
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{
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/* eat until end of line */
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while ( (c=getc (fp)) != EOF && c != '\n')
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;
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fclose (fp);
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xfree (policies);
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return *line? GNUPG_Line_Too_Long: GNUPG_Incomplete_Line;
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}
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/* Allow for empty lines and spaces */
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for (p=line; spacep (p); p++)
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;
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}
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while (!*p || *p == '\n' || *p == '#');
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/* parse line */
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for (allowed=line; spacep (allowed); allowed++)
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;
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p = strpbrk (allowed, " :\n");
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if (!*p || p == allowed)
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{
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fclose (fp);
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xfree (policies);
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return GNUPG_Configuration_Error;
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}
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*p = 0; /* strip the rest of the line */
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/* See whether we find ALLOWED (which is an OID) in POLICIES */
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for (haystack=policies; (p=strstr (haystack, allowed)); haystack = p+1)
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{
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if ( !(p == policies || p[-1] == '\n') )
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continue; /* does not match the begin of a line */
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if (p[strlen (allowed)] != ':')
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continue; /* the length does not match */
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/* Yep - it does match so return okay */
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fclose (fp);
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xfree (policies);
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return 0;
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}
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}
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}
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static int
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find_up (KEYDB_HANDLE kh, KsbaCert cert, const char *issuer)
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{
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KsbaName authid;
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KsbaSexp authidno;
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int rc = -1;
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if (!ksba_cert_get_auth_key_id (cert, NULL, &authid, &authidno))
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{
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const char *s = ksba_name_enum (authid, 0);
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if (s && *authidno)
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{
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rc = keydb_search_issuer_sn (kh, s, authidno);
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if (rc)
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keydb_search_reset (kh);
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}
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ksba_name_release (authid);
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xfree (authidno);
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}
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if (rc)
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rc = keydb_search_subject (kh, issuer);
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return rc;
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}
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/* Return the next certificate up in the chain starting at START.
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Returns -1 when there are no more certificates. */
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int
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gpgsm_walk_cert_chain (KsbaCert start, KsbaCert *r_next)
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{
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int rc = 0;
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char *issuer = NULL;
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char *subject = NULL;
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KEYDB_HANDLE kh = keydb_new (0);
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*r_next = NULL;
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if (!kh)
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{
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log_error (_("failed to allocated keyDB handle\n"));
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rc = GNUPG_General_Error;
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goto leave;
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}
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issuer = ksba_cert_get_issuer (start, 0);
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subject = ksba_cert_get_subject (start, 0);
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if (!issuer)
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{
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log_error ("no issuer found in certificate\n");
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rc = GNUPG_Bad_Certificate;
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goto leave;
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}
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if (!subject)
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{
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log_error ("no subject found in certificate\n");
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rc = GNUPG_Bad_Certificate;
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goto leave;
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}
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if (!strcmp (issuer, subject))
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{
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rc = -1; /* we are at the root */
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goto leave;
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}
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rc = find_up (kh, start, issuer);
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if (rc)
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{
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/* it is quite common not to have a certificate, so better don't
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print an error here */
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if (rc != -1 && opt.verbose > 1)
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log_error ("failed to find issuer's certificate: rc=%d\n", rc);
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rc = GNUPG_Missing_Certificate;
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goto leave;
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}
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rc = keydb_get_cert (kh, r_next);
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if (rc)
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{
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log_error ("failed to get cert: rc=%d\n", rc);
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rc = GNUPG_General_Error;
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}
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leave:
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xfree (issuer);
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xfree (subject);
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keydb_release (kh);
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return rc;
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}
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/* Check whether the CERT is a root certificate. Returns True if this
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is the case. */
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int
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gpgsm_is_root_cert (KsbaCert cert)
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{
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char *issuer;
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char *subject;
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int yes;
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issuer = ksba_cert_get_issuer (cert, 0);
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subject = ksba_cert_get_subject (cert, 0);
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yes = (issuer && subject && !strcmp (issuer, subject));
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xfree (issuer);
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xfree (subject);
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return yes;
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}
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int
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gpgsm_validate_path (KsbaCert cert)
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{
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int rc = 0, depth = 0, maxdepth;
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char *issuer = NULL;
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char *subject = NULL;
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KEYDB_HANDLE kh = keydb_new (0);
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KsbaCert subject_cert = NULL, issuer_cert = NULL;
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time_t current_time = time (NULL);
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if ((opt.debug & 4096))
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{
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log_info ("WARNING: bypassing path validation\n");
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return 0;
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}
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if (!kh)
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{
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log_error (_("failed to allocated keyDB handle\n"));
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rc = GNUPG_General_Error;
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goto leave;
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}
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if (DBG_X509)
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gpgsm_dump_cert ("subject", cert);
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subject_cert = cert;
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maxdepth = 50;
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for (;;)
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{
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xfree (issuer);
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xfree (subject);
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issuer = ksba_cert_get_issuer (subject_cert, 0);
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subject = ksba_cert_get_subject (subject_cert, 0);
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if (!issuer)
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{
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log_error ("no issuer found in certificate\n");
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rc = GNUPG_Bad_Certificate;
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goto leave;
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}
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{
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time_t not_before, not_after;
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not_before = ksba_cert_get_validity (subject_cert, 0);
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not_after = ksba_cert_get_validity (subject_cert, 1);
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if (not_before == (time_t)(-1) || not_after == (time_t)(-1))
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{
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log_error ("certificate with invalid validity\n");
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rc = GNUPG_Bad_Certificate;
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goto leave;
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}
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if (current_time < not_before)
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{
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log_error ("certificate to young; valid from ");
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gpgsm_dump_time (not_before);
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log_printf ("\n");
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rc = GNUPG_Certificate_Too_Young;
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goto leave;
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}
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if (current_time > not_after)
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{
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log_error ("certificate has expired at ");
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gpgsm_dump_time (not_after);
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log_printf ("\n");
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rc = GNUPG_Certificate_Expired;
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goto leave;
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}
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}
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rc = unknown_criticals (subject_cert);
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if (rc)
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goto leave;
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if (!opt.no_policy_check)
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{
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rc = check_cert_policy (subject_cert);
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if (rc)
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goto leave;
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}
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if (!opt.no_crl_check)
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{
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rc = gpgsm_dirmngr_isvalid (subject_cert);
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if (rc)
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{
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switch (rc)
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{
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case GNUPG_Certificate_Revoked:
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log_error (_("the certificate has been revoked\n"));
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break;
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case GNUPG_No_CRL_Known:
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log_error (_("no CRL found for certificate\n"));
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break;
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case GNUPG_CRL_Too_Old:
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log_error (_("the available CRL is too old\n"));
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log_info (_("please make sure that the "
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"\"dirmngr\" is properly installed\n"));
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break;
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default:
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log_error (_("checking the CRL failed: %s\n"),
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gnupg_strerror (rc));
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break;
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}
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goto leave;
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}
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}
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if (subject && !strcmp (issuer, subject))
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{
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if (gpgsm_check_cert_sig (subject_cert, subject_cert) )
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{
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log_error ("selfsigned certificate has a BAD signatures\n");
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rc = depth? GNUPG_Bad_Certificate_Path : GNUPG_Bad_Certificate;
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goto leave;
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}
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rc = allowed_ca (subject_cert, NULL);
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if (rc)
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goto leave;
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rc = gpgsm_agent_istrusted (subject_cert);
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if (!rc)
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;
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else if (rc == GNUPG_Not_Trusted)
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{
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int rc2;
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char *fpr = gpgsm_get_fingerprint_string (subject_cert,
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GCRY_MD_SHA1);
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log_info (_("root certificate is not marked trusted\n"));
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log_info (_("fingerprint=%s\n"), fpr? fpr : "?");
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xfree (fpr);
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rc2 = gpgsm_agent_marktrusted (subject_cert);
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if (!rc2)
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{
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log_info (_("root certificate has now"
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" been marked as trusted\n"));
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rc = 0;
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}
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else
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{
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gpgsm_dump_cert ("issuer", subject_cert);
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log_info ("after checking the fingerprint, you may want "
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"to enter it manually into "
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"\"~/.gnupg-test/trustlist.txt\"\n");
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}
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}
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else
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{
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log_error (_("checking the trust list failed: %s\n"),
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gnupg_strerror (rc));
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}
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break; /* okay, a self-signed certicate is an end-point */
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}
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depth++;
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if (depth > maxdepth)
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{
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log_error (_("certificate path too long\n"));
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rc = GNUPG_Bad_Certificate_Path;
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goto leave;
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}
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/* find the next cert up the tree */
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keydb_search_reset (kh);
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rc = find_up (kh, subject_cert, issuer);
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if (rc)
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{
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if (rc == -1)
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{
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log_info ("issuer certificate (");
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gpgsm_dump_string (issuer);
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log_printf (") not found\n");
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}
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else
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log_error ("failed to find issuer's certificate: rc=%d\n", rc);
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rc = GNUPG_Missing_Certificate;
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goto leave;
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}
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ksba_cert_release (issuer_cert); issuer_cert = NULL;
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rc = keydb_get_cert (kh, &issuer_cert);
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if (rc)
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{
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log_error ("failed to get cert: rc=%d\n", rc);
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rc = GNUPG_General_Error;
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goto leave;
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}
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if (DBG_X509)
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{
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log_debug ("got issuer's certificate:\n");
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gpgsm_dump_cert ("issuer", issuer_cert);
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}
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if (gpgsm_check_cert_sig (issuer_cert, subject_cert) )
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{
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log_error ("certificate has a BAD signatures\n");
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rc = GNUPG_Bad_Certificate_Path;
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goto leave;
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}
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{
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int pathlen;
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rc = allowed_ca (issuer_cert, &pathlen);
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if (rc)
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goto leave;
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if (pathlen >= 0 && (depth - 1) > pathlen)
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{
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log_error (_("certificate path longer than allowed by CA (%d)\n"),
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pathlen);
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rc = GNUPG_Bad_Certificate_Path;
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goto leave;
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}
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}
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log_info ("certificate is good\n");
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keydb_search_reset (kh);
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subject_cert = issuer_cert;
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issuer_cert = NULL;
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}
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if (opt.no_policy_check)
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log_info ("policies not checked due to --disable-policy-checks option\n");
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if (opt.no_crl_check)
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log_info ("CRLs not checked due to --disable-crl-checks option\n");
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leave:
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xfree (issuer);
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keydb_release (kh);
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ksba_cert_release (issuer_cert);
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if (subject_cert != cert)
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ksba_cert_release (subject_cert);
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return rc;
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}
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/* Check that the given certificate is valid but DO NOT check any
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constraints. We assume that the issuers certificate is already in
|
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the DB and that this one is valid; which it should be because it
|
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has been checked using this function. */
|
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int
|
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gpgsm_basic_cert_check (KsbaCert cert)
|
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{
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int rc = 0;
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char *issuer = NULL;
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char *subject = NULL;
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KEYDB_HANDLE kh = keydb_new (0);
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KsbaCert issuer_cert = NULL;
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if ((opt.debug & 4096))
|
||
{
|
||
log_info ("WARNING: bypassing basic certificate checks\n");
|
||
return 0;
|
||
}
|
||
|
||
if (!kh)
|
||
{
|
||
log_error (_("failed to allocated keyDB handle\n"));
|
||
rc = GNUPG_General_Error;
|
||
goto leave;
|
||
}
|
||
|
||
issuer = ksba_cert_get_issuer (cert, 0);
|
||
subject = ksba_cert_get_subject (cert, 0);
|
||
if (!issuer)
|
||
{
|
||
log_error ("no issuer found in certificate\n");
|
||
rc = GNUPG_Bad_Certificate;
|
||
goto leave;
|
||
}
|
||
|
||
if (subject && !strcmp (issuer, subject))
|
||
{
|
||
if (gpgsm_check_cert_sig (cert, cert) )
|
||
{
|
||
log_error ("selfsigned certificate has a BAD signatures\n");
|
||
rc = GNUPG_Bad_Certificate;
|
||
goto leave;
|
||
}
|
||
}
|
||
else
|
||
{
|
||
/* find the next cert up the tree */
|
||
keydb_search_reset (kh);
|
||
rc = find_up (kh, cert, issuer);
|
||
if (rc)
|
||
{
|
||
if (rc == -1)
|
||
{
|
||
log_info ("issuer certificate (");
|
||
gpgsm_dump_string (issuer);
|
||
log_printf (") not found\n");
|
||
}
|
||
else
|
||
log_error ("failed to find issuer's certificate: rc=%d\n", rc);
|
||
rc = GNUPG_Missing_Certificate;
|
||
goto leave;
|
||
}
|
||
|
||
ksba_cert_release (issuer_cert); issuer_cert = NULL;
|
||
rc = keydb_get_cert (kh, &issuer_cert);
|
||
if (rc)
|
||
{
|
||
log_error ("failed to get cert: rc=%d\n", rc);
|
||
rc = GNUPG_General_Error;
|
||
goto leave;
|
||
}
|
||
|
||
if (gpgsm_check_cert_sig (issuer_cert, cert) )
|
||
{
|
||
log_error ("certificate has a BAD signatures\n");
|
||
rc = GNUPG_Bad_Certificate;
|
||
goto leave;
|
||
}
|
||
if (opt.verbose)
|
||
log_info ("certificate is good\n");
|
||
}
|
||
|
||
leave:
|
||
xfree (issuer);
|
||
keydb_release (kh);
|
||
ksba_cert_release (issuer_cert);
|
||
return rc;
|
||
}
|
||
|