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/*
* Copyright (c) 1999, 2001, 2003 Todd C. Miller <Todd.Miller@courtesan.com>
* All rights reserved.
*
* This code is derived from software contributed by Frank Cusack
* <fcusack@fcusack.com>.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* 4. Products derived from this software may not be called "Sudo" nor
* may "Sudo" appear in their names without specific prior written
* permission from the author.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
* THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include <sys/types.h>
#include <sys/param.h>
#include <stdio.h>
#ifdef STDC_HEADERS
# include <stdlib.h>
# include <stddef.h>
#else
# ifdef HAVE_STDLIB_H
# include <stdlib.h>
# endif
#endif /* STDC_HEADERS */
#ifdef HAVE_STRING_H
# include <string.h>
#else
# ifdef HAVE_STRINGS_H
# include <strings.h>
# endif
#endif /* HAVE_STRING_H */
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif /* HAVE_UNISTD_H */
#include <pwd.h>
#include <krb5.h>
#include "sudo.h"
#include "sudo_auth.h"
#ifndef lint
static const char rcsid[] = "$Sudo: kerb5.c,v 1.14 2003/04/02 18:57:34 millert Exp $";
#endif /* lint */
static int verify_krb_v5_tgt __P((krb5_context, krb5_ccache, char *));
static struct _sudo_krb5_data {
krb5_context sudo_context;
krb5_principal princ;
krb5_ccache ccache;
} sudo_krb5_data = { NULL, NULL, NULL };
typedef struct _sudo_krb5_data *sudo_krb5_datap;
extern krb5_cc_ops krb5_mcc_ops;
int
kerb5_init(pw, promptp, auth)
struct passwd *pw;
char **promptp;
sudo_auth *auth;
{
krb5_context sudo_context;
krb5_ccache ccache;
krb5_principal princ;
krb5_error_code error;
char cache_name[64];
char *pname;
auth->data = (VOID *) &sudo_krb5_data; /* Stash all our data here */
if ((error = krb5_init_context(&(sudo_krb5_data.sudo_context))))
return(AUTH_FAILURE);
sudo_context = sudo_krb5_data.sudo_context;
if ((error = krb5_parse_name(sudo_context, pw->pw_name,
&(sudo_krb5_data.princ)))) {
log_error(NO_EXIT|NO_MAIL,
"%s: unable to parse '%s': %s", auth->name, pw->pw_name,
error_message(error));
return(AUTH_FAILURE);
}
princ = sudo_krb5_data.princ;
/*
* Really, we need to tell the caller not to prompt for password.
* The API does not currently provide this unless the auth is standalone.
*/
#if 1
if ((error = krb5_unparse_name(sudo_context, princ, &pname))) {
log_error(NO_EXIT|NO_MAIL,
"%s: unable to unparse princ ('%s'): %s", auth->name,
pw->pw_name, error_message(error));
return(AUTH_FAILURE);
}
/* Only rewrite prompt if user didn't specify their own. */
/*if (!strcmp(prompt, PASSPROMPT)) { */
easprintf(promptp, "Password for %s: ", pname);
/*}*/
free(pname);
#endif
/* For CNS compatibility */
if ((error = krb5_cc_register(sudo_context, &krb5_mcc_ops, FALSE))) {
if (error != KRB5_CC_TYPE_EXISTS) {
log_error(NO_EXIT|NO_MAIL,
"%s: unable to use Memory ccache: %s", auth->name,
error_message(error));
return(AUTH_FAILURE);
}
}
(void) snprintf(cache_name, sizeof(cache_name), "MEMORY:sudocc_%ld",
(long) getpid());
if ((error = krb5_cc_resolve(sudo_context, cache_name,
&(sudo_krb5_data.ccache)))) {
log_error(NO_EXIT|NO_MAIL,
"%s: unable to resolve ccache: %s", auth->name,
error_message(error));
return(AUTH_FAILURE);
}
ccache = sudo_krb5_data.ccache;
if ((error = krb5_cc_initialize(sudo_context, ccache, princ))) {
log_error(NO_EXIT|NO_MAIL,
"%s: unable to initialize ccache: %s", auth->name,
error_message(error));
return(AUTH_FAILURE);
}
return(AUTH_SUCCESS);
}
int
kerb5_verify(pw, pass, auth)
struct passwd *pw;
char *pass;
sudo_auth *auth;
{
krb5_context sudo_context;
krb5_principal princ;
krb5_ccache ccache;
krb5_creds creds;
krb5_error_code error;
krb5_get_init_creds_opt opts;
sudo_context = ((sudo_krb5_datap) auth->data)->sudo_context;
princ = ((sudo_krb5_datap) auth->data)->princ;
ccache = ((sudo_krb5_datap) auth->data)->ccache;
/* Initialize options to defaults */
krb5_get_init_creds_opt_init(&opts);
/* Note that we always obtain a new TGT to verify the user */
if ((error = krb5_get_init_creds_password(sudo_context, &creds, princ,
pass, krb5_prompter_posix,
NULL, 0, NULL, &opts))) {
if (error == KRB5KRB_AP_ERR_BAD_INTEGRITY) /* Bad password */
return(AUTH_FAILURE);
/* Some other error */
log_error(NO_EXIT|NO_MAIL,
"%s: unable to get credentials: %s", auth->name,
error_message(error));
return(AUTH_FAILURE);
}
/* Stash the TGT so we can verify it. */
if ((error = krb5_cc_store_cred(sudo_context, ccache, &creds))) {
log_error(NO_EXIT|NO_MAIL,
"%s: unable to store credentials: %s", auth->name,
error_message(error));
} else {
error = verify_krb_v5_tgt(sudo_context, ccache, auth->name);
}
krb5_free_cred_contents(sudo_context, &creds);
return (error ? AUTH_FAILURE : AUTH_SUCCESS);
}
int
kerb5_cleanup(pw, auth)
struct passwd *pw;
sudo_auth *auth;
{
krb5_context sudo_context;
krb5_principal princ;
krb5_ccache ccache;
sudo_context = ((sudo_krb5_datap) auth->data)->sudo_context;
princ = ((sudo_krb5_datap) auth->data)->princ;
ccache = ((sudo_krb5_datap) auth->data)->ccache;
if (sudo_context) {
if (ccache)
krb5_cc_destroy(sudo_context, ccache);
if (princ)
krb5_free_principal(sudo_context, princ);
krb5_free_context(sudo_context);
}
return(AUTH_SUCCESS);
}
/*
* This routine with some modification is from the MIT V5B6 appl/bsd/login.c
*
* Verify the Kerberos ticket-granting ticket just retrieved for the
* user. If the Kerberos server doesn't respond, assume the user is
* trying to fake us out (since we DID just get a TGT from what is
* supposedly our KDC). If the host/<host> service is unknown (i.e.,
* the local keytab doesn't have it), return success but log the error.
*
* This needs to run as root (to read the host service ticket).
*
* Returns 0 for successful authentication, non-zero for failure.
*/
static int
verify_krb_v5_tgt(sudo_context, ccache, auth_name)
krb5_context sudo_context;
krb5_ccache ccache;
char *auth_name; /* For error reporting */
{
char phost[BUFSIZ];
krb5_error_code error;
krb5_principal princ;
krb5_data packet;
krb5_keyblock *keyblock = 0;
krb5_auth_context auth_context = NULL;
packet.data = 0;
/*
* Get the server principal for the local host.
* (Use defaults of "host" and canonicalized local name.)
*/
if ((error = krb5_sname_to_principal(sudo_context, NULL, NULL,
KRB5_NT_SRV_HST, &princ))) {
log_error(NO_EXIT|NO_MAIL,
"%s: unable to get host principal: %s", auth_name,
error_message(error));
return(-1);
}
/* Extract the name directly. */
strlcpy(phost, krb5_principal_get_realm(sudo_context, princ),
sizeof(phost));
/*
* Do we have host/<host> keys?
* (use default keytab, kvno IGNORE_VNO to get the first match,
* and enctype is currently ignored anyhow.)
*/
if ((error = krb5_kt_read_service_key(sudo_context, NULL, princ, 0,
ETYPE_DES_CBC_MD5, &keyblock))) {
/* Keytab or service key does not exist. */
log_error(NO_EXIT,
"%s: host service key not found: %s", auth_name,
error_message(error));
error = 0;
goto cleanup;
}
if (keyblock)
krb5_free_keyblock(sudo_context, keyblock);
/* Talk to the kdc and construct the ticket. */
error = krb5_mk_req(sudo_context, &auth_context, 0, "host", phost,
NULL, ccache, &packet);
if (auth_context) {
krb5_auth_con_free(sudo_context, auth_context);
auth_context = NULL; /* setup for rd_req */
}
/* Try to use the ticket. */
if (!error)
error = krb5_rd_req(sudo_context, &auth_context, &packet, princ,
NULL, NULL, NULL);
cleanup:
if (packet.data)
krb5_data_free(&packet);
krb5_free_principal(sudo_context, princ);
if (error)
log_error(NO_EXIT|NO_MAIL,
"%s: Cannot verify TGT! Possible attack!: %s", auth_name,
error_message(error));
return(error);
}
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