273 lines
6.9 KiB
C
273 lines
6.9 KiB
C
/* $OpenBSD: auth-krb5.c,v 1.23 2018/07/09 21:35:50 markus Exp $ */
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/*
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* Kerberos v5 authentication and ticket-passing routines.
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*
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* From: FreeBSD: src/crypto/openssh/auth-krb5.c,v 1.6 2001/02/13 16:58:04 assar
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*/
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/*
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* Copyright (c) 2002 Daniel Kouril. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "includes.h"
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#include <sys/types.h>
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#include <pwd.h>
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#include <stdarg.h>
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#include "xmalloc.h"
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#include "ssh.h"
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#include "packet.h"
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#include "log.h"
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#include "sshbuf.h"
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#include "sshkey.h"
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#include "misc.h"
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#include "servconf.h"
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#include "uidswap.h"
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#include "hostfile.h"
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#include "auth.h"
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#ifdef KRB5
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#include <errno.h>
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#include <unistd.h>
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#include <string.h>
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#include <krb5.h>
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extern ServerOptions options;
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static int
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krb5_init(void *context)
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{
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Authctxt *authctxt = (Authctxt *)context;
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krb5_error_code problem;
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if (authctxt->krb5_ctx == NULL) {
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problem = krb5_init_context(&authctxt->krb5_ctx);
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if (problem)
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return (problem);
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}
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return (0);
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}
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int
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auth_krb5_password(Authctxt *authctxt, const char *password)
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{
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#ifndef HEIMDAL
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krb5_creds creds;
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krb5_principal server;
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#endif
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krb5_error_code problem;
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krb5_ccache ccache = NULL;
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int len;
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char *client, *platform_client;
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const char *errmsg;
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/* get platform-specific kerberos client principal name (if it exists) */
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platform_client = platform_krb5_get_principal_name(authctxt->pw->pw_name);
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client = platform_client ? platform_client : authctxt->pw->pw_name;
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temporarily_use_uid(authctxt->pw);
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problem = krb5_init(authctxt);
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if (problem)
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goto out;
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problem = krb5_parse_name(authctxt->krb5_ctx, client,
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&authctxt->krb5_user);
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if (problem)
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goto out;
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#ifdef HEIMDAL
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# ifdef HAVE_KRB5_CC_NEW_UNIQUE
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problem = krb5_cc_new_unique(authctxt->krb5_ctx,
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krb5_mcc_ops.prefix, NULL, &ccache);
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# else
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problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_mcc_ops, &ccache);
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# endif
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if (problem)
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goto out;
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problem = krb5_cc_initialize(authctxt->krb5_ctx, ccache,
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authctxt->krb5_user);
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if (problem)
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goto out;
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restore_uid();
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problem = krb5_verify_user(authctxt->krb5_ctx, authctxt->krb5_user,
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ccache, password, 1, NULL);
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temporarily_use_uid(authctxt->pw);
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if (problem)
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goto out;
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# ifdef HAVE_KRB5_CC_NEW_UNIQUE
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problem = krb5_cc_new_unique(authctxt->krb5_ctx,
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krb5_fcc_ops.prefix, NULL, &authctxt->krb5_fwd_ccache);
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# else
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problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_fcc_ops,
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&authctxt->krb5_fwd_ccache);
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# endif
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if (problem)
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goto out;
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problem = krb5_cc_copy_cache(authctxt->krb5_ctx, ccache,
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authctxt->krb5_fwd_ccache);
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krb5_cc_destroy(authctxt->krb5_ctx, ccache);
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ccache = NULL;
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if (problem)
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goto out;
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#else
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problem = krb5_get_init_creds_password(authctxt->krb5_ctx, &creds,
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authctxt->krb5_user, (char *)password, NULL, NULL, 0, NULL, NULL);
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if (problem)
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goto out;
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problem = krb5_sname_to_principal(authctxt->krb5_ctx, NULL, NULL,
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KRB5_NT_SRV_HST, &server);
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if (problem)
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goto out;
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restore_uid();
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problem = krb5_verify_init_creds(authctxt->krb5_ctx, &creds, server,
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NULL, NULL, NULL);
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krb5_free_principal(authctxt->krb5_ctx, server);
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temporarily_use_uid(authctxt->pw);
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if (problem)
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goto out;
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if (!krb5_kuserok(authctxt->krb5_ctx, authctxt->krb5_user,
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authctxt->pw->pw_name)) {
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problem = -1;
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goto out;
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}
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problem = ssh_krb5_cc_gen(authctxt->krb5_ctx, &authctxt->krb5_fwd_ccache);
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if (problem)
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goto out;
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problem = krb5_cc_initialize(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache,
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authctxt->krb5_user);
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if (problem)
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goto out;
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problem= krb5_cc_store_cred(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache,
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&creds);
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if (problem)
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goto out;
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#endif
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authctxt->krb5_ticket_file = (char *)krb5_cc_get_name(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
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len = strlen(authctxt->krb5_ticket_file) + 6;
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authctxt->krb5_ccname = xmalloc(len);
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snprintf(authctxt->krb5_ccname, len, "FILE:%s",
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authctxt->krb5_ticket_file);
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#ifdef USE_PAM
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if (options.use_pam)
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do_pam_putenv("KRB5CCNAME", authctxt->krb5_ccname);
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#endif
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out:
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restore_uid();
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free(platform_client);
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if (problem) {
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if (ccache)
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krb5_cc_destroy(authctxt->krb5_ctx, ccache);
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if (authctxt->krb5_ctx != NULL && problem!=-1) {
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errmsg = krb5_get_error_message(authctxt->krb5_ctx,
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problem);
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debug("Kerberos password authentication failed: %s",
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errmsg);
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krb5_free_error_message(authctxt->krb5_ctx, errmsg);
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} else
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debug("Kerberos password authentication failed: %d",
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problem);
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krb5_cleanup_proc(authctxt);
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if (options.kerberos_or_local_passwd)
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return (-1);
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else
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return (0);
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}
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return (authctxt->valid ? 1 : 0);
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}
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void
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krb5_cleanup_proc(Authctxt *authctxt)
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{
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debug("krb5_cleanup_proc called");
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if (authctxt->krb5_fwd_ccache) {
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krb5_cc_destroy(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
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authctxt->krb5_fwd_ccache = NULL;
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}
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if (authctxt->krb5_user) {
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krb5_free_principal(authctxt->krb5_ctx, authctxt->krb5_user);
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authctxt->krb5_user = NULL;
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}
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if (authctxt->krb5_ctx) {
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krb5_free_context(authctxt->krb5_ctx);
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authctxt->krb5_ctx = NULL;
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}
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}
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#ifndef HEIMDAL
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krb5_error_code
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ssh_krb5_cc_gen(krb5_context ctx, krb5_ccache *ccache) {
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int tmpfd, ret, oerrno;
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char ccname[40];
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mode_t old_umask;
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ret = snprintf(ccname, sizeof(ccname),
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"FILE:/tmp/krb5cc_%d_XXXXXXXXXX", geteuid());
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if (ret < 0 || (size_t)ret >= sizeof(ccname))
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return ENOMEM;
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old_umask = umask(0177);
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tmpfd = mkstemp(ccname + strlen("FILE:"));
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oerrno = errno;
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umask(old_umask);
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if (tmpfd == -1) {
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logit("mkstemp(): %.100s", strerror(oerrno));
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return oerrno;
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}
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if (fchmod(tmpfd,S_IRUSR | S_IWUSR) == -1) {
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oerrno = errno;
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logit("fchmod(): %.100s", strerror(oerrno));
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close(tmpfd);
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return oerrno;
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}
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close(tmpfd);
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return (krb5_cc_resolve(ctx, ccname, ccache));
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}
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#endif /* !HEIMDAL */
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#endif /* KRB5 */
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