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Add pam_ksu(8), a module to do Kerberos 5 authentication and

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$HOME/.k5login authorization for su(1).

Reviewed by:	des (earlier version)
This commit is contained in:
Jacques Vidrine 2002-05-28 20:52:31 +00:00
parent 43c6b63e82
commit 3a27166692
4 changed files with 412 additions and 0 deletions
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1
lib/libpam/modules/modules.inc
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@ -11,6 +11,7 @@ MODULES += pam_kerberosIV
.endif
.if defined(MAKE_KERBEROS5) && !defined(NOCRYPT) && !defined(NO_OPENSSL)
MODULES += pam_krb5
MODULES += pam_ksu
.endif
MODULES += pam_lastlog
MODULES += pam_login_access

42
lib/libpam/modules/pam_ksu/Makefile Normal file
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@ -0,0 +1,42 @@
# Copyright 2002 FreeBSD, Inc.
# All rights reserved.
#
# 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.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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.
#
# $FreeBSD$
PAMDIR= ${.CURDIR}/../../../../contrib/libpam
LIB= pam_ksu
SRCS= pam_ksu.c
CFLAGS+= -Wall
CFLAGS+= -I${PAMDIR}/libpam/include
CFLAGS+= -I${.CURDIR}/../../libpam
DPADD= ${LIBKRB5} ${LIBASN1} ${LIBCRYPTO} ${LIBCRYPT} \
${LIBCOM_ERR} ${LIBROKEN}
LDADD= -lkrb5 -lasn1 -lcrypto -lcrypt -lcom_err \
-L${.OBJDIR}/../../../../kerberos5/lib/libroken -lroken
MAN= pam_ksu.8
#INTERNALLIB= yes
#INTERNALSTATICLIB=yes
.include <bsd.lib.mk>

113
lib/libpam/modules/pam_ksu/pam_ksu.8 Normal file
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@ -0,0 +1,113 @@
.\" Copyright (c) 2001 Mark R V Murray
.\" All rights reserved.
.\" Copyright (c) 2001 Networks Associates Technology, Inc.
.\" All rights reserved.
.\"
.\" This software was developed for the FreeBSD Project by ThinkSec AS and
.\" NAI Labs, the Security Research Division of Network Associates, Inc.
.\" under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
.\" DARPA CHATS research program.
.\"
.\" 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.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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.
.\"
.\" $FreeBSD$
.\"
.Dd May 15, 2002
.Dt pam_ksu 8
.Os
.Sh NAME
.Nm pam_ksu
.Nd Kerberos 5 SU PAM module
.Sh SYNOPSIS
.Op Ar service-name
.Ar module-type
.Ar control-flag
.Pa pam_ksu
.Op Ar options
.Sh DESCRIPTION
The Kerberos 5 SU authentication service module for PAM,
.Nm
for only one PAM category: authentication.
In terms of the
.Ar module-type
parameter, this is the
.Dq Li auth
feature.
The module is specifically designed to be used with the
.Xr su 1
utility.
.\" It also provides a null function for session management.
.Ss Kerberos 5 SU Authentication Module
The Kerberos 5 SU authentication component provides functions to verify
the identity of a user
.Pq Fn pam_sm_authenticate ,
and determine whether or not the user is authorized to obtain the
privileges of the target account.
If the target account is `root', then the Kerberos 5 principal used
for authentication and authorization will be the `root' instance of
the current user, e.g. `user/root@REAL.M'.
Otherwise, the principal will simply be the current user's default
principal, e.g. `user@REAL.M'.
.Pp
The user is prompted for a password if necessary. Authorization is performed
by comparing the Kerberos 5 principal with those listed in the
.Pa .k5login
file in the target account's home directory
.Pq e.g. /root/.k5login for root .
.Pp
The following options may be passed to the authentication module:
.Bl -tag -width ".Cm use_first_pass"
.It Cm debug
.Xr syslog 3
debugging information at
.Dv LOG_DEBUG
level.
.It Cm use_first_pass
If the authentication module
is not the first in the stack,
and a previous module
obtained the user's password,
that password is used
to authenticate the user.
If this fails,
the authentication module returns failure
without prompting the user for a password.
This option has no effect
if the authentication module
is the first in the stack,
or if no previous modules
obtained the user's password.
.It Cm try_first_pass
This option is similar to the
.Cm use_first_pass
option,
except that if the previously obtained password fails,
the user is prompted for another password.
.El
.Sh SEE ALSO
.Xr su 1 ,
.Xr syslog 3 ,
.Xr pam.conf 5 ,
.Xr pam 8

256
lib/libpam/modules/pam_ksu/pam_ksu.c Normal file
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@ -0,0 +1,256 @@
/*-
* Copyright (c) 2002 Jacques A. Vidrine <nectar@FreeBSD.org>
* All rights reserved.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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 <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <krb5.h>
#define PAM_SM_AUTH
#define PAM_SM_CRED
#include <security/pam_appl.h>
#include <security/pam_modules.h>
#include <security/pam_mod_misc.h>
static const char superuser[] = "root";
static long get_su_principal(krb5_context, const char *, const char *,
char **, krb5_principal *);
static int auth_krb5(pam_handle_t *, krb5_context, const char *,
krb5_principal);
PAM_EXTERN int
pam_sm_authenticate(pam_handle_t *pamh, int flags __unused,
int argc __unused, const char *argv[] __unused)
{
krb5_context context;
krb5_principal su_principal;
const char *user, *ruser;
char *su_principal_name;
long rv;
int pamret;
pamret = pam_get_user(pamh, &user, NULL);
if (pamret != PAM_SUCCESS)
return (pamret);
PAM_LOG("Got user: %s", user);
pamret = pam_get_item(pamh, PAM_RUSER, (const void **)&ruser);
if (pamret != PAM_SUCCESS)
return (pamret);
PAM_LOG("Got ruser: %s", ruser);
rv = krb5_init_context(&context);
if (rv != 0) {
PAM_LOG("krb5_init_context failed: %s",
krb5_get_err_text(context, rv));
return (PAM_SERVICE_ERR);
}
rv = get_su_principal(context, user, ruser, &su_principal_name, &su_principal);
if (rv != 0)
return (PAM_AUTH_ERR);
PAM_LOG("kuserok: %s -> %s", su_principal_name, user);
rv = krb5_kuserok(context, su_principal, user);
pamret = rv ? auth_krb5(pamh, context, su_principal_name, su_principal) : PAM_AUTH_ERR;
free(su_principal_name);
krb5_free_principal(context, su_principal);
krb5_free_context(context);
return (pamret);
}
PAM_EXTERN int
pam_sm_setcred(pam_handle_t *pamh __unused, int flags __unused,
int ac __unused, const char *av[] __unused)
{
return (PAM_SUCCESS);
}
/* Authenticate using Kerberos 5.
* pamh -- The PAM handle.
* context -- An initialized krb5_context.
* su_principal_name -- The target principal name, used only for password prompts.
* If NULL, the password prompts will not include a principal
* name.
* su_principal -- The target krb5_principal.
* Note that a valid keytab in the default location with a host entry
* must be available, and that the PAM application must have sufficient
* privileges to access it.
* Returns PAM_SUCCESS if authentication was successful, or an appropriate
* PAM error code if it was not.
*/
static int
auth_krb5(pam_handle_t *pamh, krb5_context context, const char *su_principal_name,
krb5_principal su_principal)
{
krb5_creds creds;
krb5_get_init_creds_opt gic_opt;
krb5_verify_init_creds_opt vic_opt;
const char *pass;
char *prompt;
long rv;
int pamret;
prompt = NULL;
krb5_get_init_creds_opt_init(&gic_opt);
krb5_verify_init_creds_opt_init(&vic_opt);
if (su_principal_name != NULL)
(void)asprintf(&prompt, "Password for %s:", su_principal_name);
else
(void)asprintf(&prompt, "Password:");
if (prompt == NULL)
return (PAM_BUF_ERR);
pass = NULL;
(void)pam_get_item(pamh, PAM_AUTHTOK, (const void **)&pass);
free(prompt);
if (pass == NULL) {
pamret = pam_get_authtok(pamh, PAM_AUTHTOK, &pass, prompt);
if (pamret != PAM_SUCCESS)
return (pamret);
}
rv = krb5_get_init_creds_password(context, &creds, su_principal,
pass, NULL, NULL, 0, NULL, &gic_opt);
if (rv != 0) {
PAM_LOG("krb5_get_init_creds_password: %s",
krb5_get_err_text(context, rv));
return (PAM_AUTH_ERR);
}
krb5_verify_init_creds_opt_set_ap_req_nofail(&vic_opt, 1);
rv = krb5_verify_init_creds(context, &creds, NULL, NULL, NULL,
&vic_opt);
krb5_free_cred_contents(context, &creds);
if (rv != 0) {
PAM_LOG("krb5_verify_init_creds: %s",
krb5_get_err_text(context, rv));
return (PAM_AUTH_ERR);
}
return (PAM_SUCCESS);
}
/* Determine the target principal given the current user and the target user.
* context -- An initialized krb5_context.
* target_user -- The target username.
* current_user -- The current username.
* su_principal_name -- (out) The target principal name.
* su_principal -- (out) The target krb5_principal.
* When the target user is `root', the target principal will be a `root
* instance', e.g. `luser/root@REA.LM'. Otherwise, the target principal
* will simply be the current user's default principal name. Note that
* in any case, if KRB5CCNAME is set and a credentials cache exists, the
* principal name found there will be the `starting point', rather than
* the ruser parameter.
*
* Returns 0 for success, or a com_err error code on failure.
*/
static long
get_su_principal(krb5_context context, const char *target_user, const char *current_user,
char **su_principal_name, krb5_principal *su_principal)
{
krb5_principal default_principal;
krb5_ccache ccache;
char *principal_name, *ccname, *p;
long rv;
uid_t euid, ruid;
*su_principal = NULL;
default_principal = NULL;
/* Unless KRB5CCNAME was explicitly set, we won't really be able
* to look at the credentials cache since krb5_cc_default will
* look at getuid().
*/
ruid = getuid();
euid = geteuid();
rv = seteuid(ruid);
if (rv != 0)
return (errno);
p = getenv("KRB5CCNAME");
if (p != NULL)
ccname = strdup(p);
else
(void)asprintf(&ccname, "%s%lu", KRB5_DEFAULT_CCROOT, (unsigned long)ruid);
if (ccname == NULL)
return (errno);
rv = krb5_cc_resolve(context, ccname, &ccache);
free(ccname);
if (rv == 0) {
rv = krb5_cc_get_principal(context, ccache, &default_principal);
krb5_cc_close(context, ccache);
if (rv != 0)
default_principal = NULL; /* just to be safe */
}
rv = seteuid(euid);
if (rv != 0)
return (errno);
if (default_principal == NULL) {
rv = krb5_make_principal(context, &default_principal, NULL, current_user, NULL);
if (rv != 0) {
PAM_LOG("Could not determine default principal name.");
return (rv);
}
}
/* Now that we have some principal, if the target account is
* `root', then transform it into a `root' instance, e.g.
* `user@REA.LM' -> `user/root@REA.LM'.
*/
rv = krb5_unparse_name(context, default_principal, &principal_name);
krb5_free_principal(context, default_principal);
if (rv != 0) {
PAM_LOG("krb5_unparse_name: %s",
krb5_get_err_text(context, rv));
return (rv);
}
PAM_LOG("Default principal name: %s", principal_name);
if (strcmp(target_user, superuser) == 0) {
p = strrchr(principal_name, '@');
if (p == NULL) {
PAM_LOG("malformed principal name `%s'", principal_name);
free(principal_name);
return (rv);
}
*p++ = '\0';
*su_principal_name = NULL;
(void)asprintf(su_principal_name, "%s/%s@%s", principal_name, superuser, p);
free(principal_name);
} else
*su_principal_name = principal_name;
if (*su_principal_name == NULL)
return (errno);
rv = krb5_parse_name(context, *su_principal_name, &default_principal);
if (rv != 0) {
PAM_LOG("krb5_parse_name `%s': %s", *su_principal_name,
krb5_get_err_text(context, rv));
free(*su_principal_name);
return (rv);
}
PAM_LOG("Target principal name: %s", *su_principal_name);
*su_principal = default_principal;
return (0);
}