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pam_tacplus.c
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pam_tacplus.c
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/* pam_tacplus.c - PAM interface for TACACS+ protocol.
*
* Copyright (C) 2010, Pawel Krawczyk <[email protected]> and
* Jeroen Nijhof <[email protected]>
*
* Copyright 2015, 2016, 2017, 2018 Cumulus Networks, Inc. All rights reserved.
*
* This program 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 2 of the License, or
* (at your option) any later version.
*
* This program 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 - see the file COPYING.
*
* See `CHANGES' file for revision history.
*/
#include "pam_tacplus.h"
#include "support.h"
#include <stdlib.h> /* malloc */
#include <stdio.h>
#include <syslog.h>
#include <netdb.h> /* gethostbyname */
#include <sys/socket.h> /* in_addr */
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdarg.h> /* va_ */
#include <signal.h>
#include <string.h> /* strdup */
#include <ctype.h>
#include <time.h>
#include <unistd.h>
#include <strings.h>
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#if defined(HAVE_OPENSSL_RAND_H) && defined(HAVE_LIBCRYPTO)
# include <openssl/rand.h>
#else
# include "libtac/lib/magic.h"
#endif
/* address of server discovered by pam_sm_authenticate */
tacplus_server_t active_server;
extern char *__vrfname;
/* privilege level, used for mapping from tacacs userid to local
* tacacs{0...15} user
*/
static unsigned priv_level;
/* accounting task identifier */
static short unsigned int task_id = 0;
/* Helper functions */
int _pam_send_account(pam_handle_t *pamh, int tac_fd, int type,
const char *user, char *tty, char *r_addr, char *cmd) {
char buf[64];
struct tac_attrib *attr = NULL;
int retval = -1;
struct areply re;
re.msg = NULL;
snprintf(buf, sizeof buf, "%lu", (unsigned long)time(NULL));
if (type == TAC_PLUS_ACCT_FLAG_START) {
tac_add_attrib(&attr, "start_time", buf);
} else if (type == TAC_PLUS_ACCT_FLAG_STOP) {
tac_add_attrib(&attr, "stop_time", buf);
}
snprintf(buf, sizeof buf, "%hu", task_id);
tac_add_attrib(&attr, "task_id", buf);
tac_add_attrib(&attr, "service", tac_service);
if(tac_protocol[0] != '\0')
tac_add_attrib(&attr, "protocol", tac_protocol);
if (cmd != NULL) {
tac_add_attrib(&attr, "cmd", cmd);
}
retval = tac_acct_send(tac_fd, type, user, tty, r_addr, attr);
/* attribute is no longer needed */
tac_free_attrib(&attr);
if(retval < 0) {
pam_syslog(pamh, LOG_WARNING, "%s: send %s accounting failed"
" (task %hu)", __func__, tac_acct_flag2str(type), task_id);
}
else if( tac_acct_read(tac_fd, &re) != TAC_PLUS_ACCT_STATUS_SUCCESS ) {
pam_syslog(pamh, LOG_WARNING, "%s: accounting %s failed (task %hu)",
__func__, tac_acct_flag2str(type), task_id);
retval = -1;
}
else
retval = 0;
if(re.msg != NULL)
free(re.msg);
return retval;
}
/*
* If all servers have been unresponsive, clear that state, so we try
* them all. It might have been transient.
*/
static void tac_chk_anyresp(void)
{
int i, anyok=0;
for(i = 0; i < tac_srv_no; i++) {
if (!tac_srv[i].not_resp)
anyok++;
}
if (!anyok) {
for(i = 0; i < tac_srv_no; i++)
tac_srv[i].not_resp = 0;
}
}
/*
* Send an accounting record to the TACACS+ server.
* We send the start/stop accounting records even if the user is not known
* to the TACACS+ server. This seems non-intuitive, but it's the way
* this code is written to work.
*/
int _pam_account(pam_handle_t *pamh, int argc, const char **argv,
int type, char *cmd) {
int retval;
int ctrl;
char *user = NULL;
char *tty = NULL;
char *r_addr = NULL;
char *typemsg;
int status = PAM_SESSION_ERR;
int srv_i, tac_fd;
typemsg = tac_acct_flag2str(type);
ctrl = _pam_parse (pamh, argc, argv);
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "%s: [%s] called (pam_tacplus"
" v%u.%u.%u)", __func__, typemsg, PAM_TAC_VMAJ, PAM_TAC_VMIN,
PAM_TAC_VPAT);
_pam_get_user(pamh, &user);
if (user == NULL)
return PAM_USER_UNKNOWN;
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "%s: username [%s] obtained", __func__,
user);
if (!task_id)
#if defined(HAVE_OPENSSL_RAND_H) && defined(HAVE_LIBCRYPTO)
RAND_pseudo_bytes((unsigned char *) &task_id, sizeof(task_id));
#else
task_id = (short unsigned int) tac_magic();
#endif
_pam_get_terminal(pamh, &tty);
if(!strncmp(tty, "/dev/", 5))
tty += 5;
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "%s: tty [%s] obtained", __func__, tty);
_pam_get_rhost(pamh, &r_addr);
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "%s: rhost [%s] obtained", __func__,
r_addr);
/* checks for specific data required by TACACS+, which should
be supplied in command line */
if(tac_protocol[0] == '\0') {
pam_syslog(pamh, LOG_ERR, "ACC: TACACS+ protocol type not configured");
return PAM_AUTHINFO_UNAVAIL;
}
/* when this module is called from within pppd or other
application dealing with serial lines, it is likely
that we will get hit with signal caused by modem hangup;
this is important only for STOP packets, it's relatively
rare that modem hangs up on accounting start */
if(type == TAC_PLUS_ACCT_FLAG_STOP) {
signal(SIGALRM, SIG_IGN);
signal(SIGCHLD, SIG_IGN);
signal(SIGHUP, SIG_IGN);
}
/*
* If PAM_SESSION_ERR is used, then the pam config can't
* ignore server failures, so use PAM_AUTHINFO_UNAVAIL.
*
* We have to make a new connection each time, because libtac is single
* threaded (doesn't support multiple connects at the same time due to
* use of globals)), and doesn't have support for persistent connections.
* That's fixable, but not worth the effort at this point.
*
* TODO: this should be converted to use do_tac_connect eventually.
*/
status = PAM_AUTHINFO_UNAVAIL;
tac_chk_anyresp();
for(srv_i = 0; srv_i < tac_srv_no; srv_i++) {
if (tac_srv[srv_i].not_resp)
continue; /* don't retry if previously not responding */
tac_fd = tac_connect_single(tac_srv[srv_i].addr, tac_srv[srv_i].key,
tac_src_addr_info, __vrfname);
if (tac_fd < 0) {
pam_syslog(pamh, LOG_WARNING, "%s: error sending %s (fd)", __func__,
typemsg);
tac_srv[srv_i].not_resp = 1;
continue;
}
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "%s: connected with fd=%d"
" to srv[%d] %s type=%s", __func__, tac_fd, srv_i,
tac_srv[srv_i].addr ? tac_ntop(tac_srv[srv_i].addr->ai_addr)
: "not set", typemsg);
retval = _pam_send_account(pamh, tac_fd, type, user, tty, r_addr, cmd);
close(tac_fd);
if (retval < 0) {
pam_syslog(pamh, LOG_WARNING, "%s: error sending %s (acct)",
__func__, typemsg);
} else {
status = PAM_SUCCESS;
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "%s: [%s] for [%s] sent",
__func__, typemsg, user);
}
if ((status == PAM_SUCCESS) && !(ctrl & PAM_TAC_ACCT)) {
/* do not send acct start/stop packets to _all_ servers */
break;
}
}
if (type == TAC_PLUS_ACCT_FLAG_STOP) {
signal(SIGALRM, SIG_DFL);
signal(SIGCHLD, SIG_DFL);
signal(SIGHUP, SIG_DFL);
}
return status;
}
/*
* Talk to the server for authentication
*/
static int tac_auth_converse(int ctrl, int fd, int *sptr,
char *pass, pam_handle_t * pamh) {
int msg;
int ret = 1;
struct areply re = { .attr = NULL, .msg = NULL, .status = 0, .flags = 0 };
struct pam_message conv_msg = { .msg_style = 0, .msg = NULL };
struct pam_response *resp = NULL;
msg = tac_authen_read(fd, &re);
if (NULL != re.msg) {
conv_msg.msg = re.msg;
}
/* talk the protocol */
switch (msg) {
case TAC_PLUS_AUTHEN_STATUS_PASS:
/* success */
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "tacacs status:"
" TAC_PLUS_AUTHEN_STATUS_PASS");
if (NULL != conv_msg.msg) {
int retval = -1;
conv_msg.msg_style = PAM_TEXT_INFO;
retval = converse(pamh, 1, &conv_msg, &resp);
if (PAM_SUCCESS == retval) {
if (PAM_TAC_DEBUG == (ctrl & PAM_TAC_DEBUG))
pam_syslog(pamh, LOG_DEBUG, "send msg=\"%s\"",
conv_msg.msg);
}
else {
pam_syslog(pamh, LOG_WARNING, "%s: error sending"
" msg=\"%s\", retval=%d", __func__, conv_msg.msg,
retval);
}
}
*sptr = PAM_SUCCESS;
ret = 0;
break;
case TAC_PLUS_AUTHEN_STATUS_FAIL:
/*
* We've already validated that the user is known, so
* this will be a password mismatch, or user not permitted
* on this host, or at this time of day, etc.
*/
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "tacacs status:"
" TAC_PLUS_AUTHEN_STATUS_FAIL");
if (NULL != conv_msg.msg) {
int retval = -1;
conv_msg.msg_style = PAM_ERROR_MSG;
retval = converse(pamh, 1, &conv_msg, &resp);
if (PAM_SUCCESS == retval) {
if (PAM_TAC_DEBUG == (ctrl & PAM_TAC_DEBUG))
pam_syslog(pamh, LOG_DEBUG, "send msg=\"%s\"",
conv_msg.msg);
}
else {
pam_syslog(pamh, LOG_WARNING, "%s: error sending msg="
"\"%s\", retval=%d", __func__, conv_msg.msg, retval);
}
}
*sptr = PAM_AUTH_ERR;
ret = 0;
pam_syslog(pamh, LOG_NOTICE, "auth failed %d", msg);
break;
case TAC_PLUS_AUTHEN_STATUS_GETDATA:
/* not implemented */
if (PAM_TAC_DEBUG == (ctrl & PAM_TAC_DEBUG))
pam_syslog(pamh, LOG_DEBUG, "tacacs status:"
" TAC_PLUS_AUTHEN_STATUS_GETDATA");
if (NULL != conv_msg.msg) {
int retval = -1;
int echo_off = (0x1 == (re.flags & 0x1));
conv_msg.msg_style = echo_off ? PAM_PROMPT_ECHO_OFF :
PAM_PROMPT_ECHO_ON;
retval = converse(pamh, 1, &conv_msg, &resp);
if (PAM_SUCCESS == retval) {
if (PAM_TAC_DEBUG == (ctrl & PAM_TAC_DEBUG))
pam_syslog(pamh, LOG_DEBUG, "sent msg=\"%s\", resp="
"\"%s\"", conv_msg.msg, resp->resp);
if (PAM_TAC_DEBUG == (ctrl & PAM_TAC_DEBUG))
pam_syslog(pamh, LOG_DEBUG, "%s: calling"
" tac_cont_send", __func__);
if (0 > tac_cont_send_seq(fd, resp->resp, re.seq_no + 1)) {
pam_syslog(pamh, LOG_ERR, "error sending continue req"
" to TACACS+ server");
*sptr = PAM_AUTHINFO_UNAVAIL;
}
}
else {
pam_syslog(pamh, LOG_WARNING, "%s: error sending msg="
"\"%s\", retval=%d (%s)", __func__, conv_msg.msg,
retval, pam_strerror(pamh, retval));
*sptr = PAM_AUTHINFO_UNAVAIL;
}
}
else {
pam_syslog(pamh, LOG_ERR, "GETDATA response with no message,"
" returning PAM_AUTHINFO_UNAVAIL");
*sptr = PAM_AUTHINFO_UNAVAIL;
}
ret = 0;
break;
case TAC_PLUS_AUTHEN_STATUS_GETUSER:
/* not implemented */
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "tacacs status:"
" TAC_PLUS_AUTHEN_STATUS_GETUSER");
ret = 0;
break;
case TAC_PLUS_AUTHEN_STATUS_GETPASS:
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "tacacs status:"
" TAC_PLUS_AUTHEN_STATUS_GETPASS");
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "%s: tac_cont_send called",
__func__);
if (tac_cont_send(fd, pass) < 0) {
pam_syslog(pamh, LOG_ERR, "error sending continue req to"
" TACACS+ server");
ret = 0;
break;
}
/* continue the while loop; go read tac response */
break;
case TAC_PLUS_AUTHEN_STATUS_RESTART:
/* try it again */
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "tacacs status:"
" TAC_PLUS_AUTHEN_STATUS_RESTART (not impl)");
/*
* not implemented
* WdJ: I *think* you can just do tac_authen_send(user, pass) again
* but I'm not sure
*/
ret = 0;
break;
case TAC_PLUS_AUTHEN_STATUS_ERROR:
/* server has problems */
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "tacacs status:"
" TAC_PLUS_AUTHEN_STATUS_ERROR");
ret = 0;
break;
case TAC_PLUS_AUTHEN_STATUS_FOLLOW:
/* server tells to try a different server address */
/* not implemented */
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "tacacs status:"
" TAC_PLUS_AUTHEN_STATUS_FOLLOW");
ret = 0;
break;
default:
if (msg < 0) {
/* connection error */
ret = 0;
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "error communicating with"
" tacacs server");
break;
}
/* unknown response code */
ret = 0;
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "tacacs status: unknown response"
" 0x%02x", msg);
}
if (NULL != resp) {
free(resp->resp);
free(resp);
}
if (NULL != re.msg);
free(re.msg);
return ret;
}
/*
* Only acct and auth now; should handle all the cases here
* Talk to the tacacs server for each type of transaction conversation
*/
static void talk_tac_server(int ctrl, int fd, char *user, char *pass,
char *tty, char *r_addr, struct tac_attrib **attr,
int *sptr, struct areply *reply,
pam_handle_t * pamh) {
if (!pass) { /* accounting */
int retval;
struct areply arep;
if (attr)
retval = tac_author_send(fd, user, tty, r_addr, *attr);
if(!attr || retval < 0) {
pam_syslog(pamh, LOG_ERR, "error getting authorization");
*sptr = PAM_AUTHINFO_UNAVAIL;
return;
}
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "%s: sent authorization request for"
" [%s]", __func__, user);
arep.msg = NULL;
tac_author_read(fd, &arep);
if (reply)
*reply = arep;
if(arep.status != AUTHOR_STATUS_PASS_ADD &&
arep.status != AUTHOR_STATUS_PASS_REPL) {
/*
* if !pass, we are validating that the user is known, and
* these status values usually means the server does not know
* about the user so set USER_UNKNOWN, so we go on to the next
* pam module. This is consistent with libnss_tacplus.
*
* If pass, then this will usually be authorization denied due
* to one of the permission checks.
*/
if (!pass) {
*sptr = PAM_USER_UNKNOWN;
/* do any logging at caller, since this is debug */
}
else {
*sptr = PAM_PERM_DENIED;
pam_syslog(pamh, LOG_WARNING, "TACACS+ authorization failed"
" for [%s] (tacacs status=%d)", user, arep.status);
}
if(arep.msg != NULL && !reply)
free (arep.msg); /* if reply is set, caller will free */
return;
}
else {
*sptr = PAM_SUCCESS;
if(arep.msg && !reply)
free (arep.msg); /* caller will free if reply is set */
}
}
else { /* authentication */
if (tac_authen_send(fd, user, pass, tty, r_addr, TAC_PLUS_AUTHEN_LOGIN)
< 0) {
pam_syslog(pamh, LOG_ERR, "error sending auth req to TACACS+"
" server");
}
else {
while ( tac_auth_converse(ctrl, fd, sptr, pass, pamh))
;
}
}
}
/*
* find a responding tacacs server, and converse with it.
* See comments at do_tac_connect() below
*/
static void find_tac_server(int ctrl, int *tacfd, char *user, char *pass,
char *tty, char *r_addr, struct tac_attrib **attr,
int *sptr, struct areply *reply,
pam_handle_t * pamh) {
int fd = -1, srv_i;
tac_chk_anyresp();
for (srv_i = 0; srv_i < tac_srv_no; srv_i++) {
fd = -1;
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "%s: trying srv[%d] %s", __func__,
srv_i, tac_srv[srv_i].addr ?
tac_ntop(tac_srv[srv_i].addr->ai_addr) : "not set");
/*
* Try using our most recent server, if we had one. This works for all
* but accounting, where we should start from beginning of list.
*/
if (active_server.addr) {
fd = tac_connect_single(active_server.addr, active_server.key,
tac_src_addr_info, __vrfname);
if (fd < 0)
active_server.addr = NULL; /* start from beginning */
}
if (fd < 0) {
if (tac_srv[srv_i].not_resp)
continue;
/* no active_server, or it failed, and curr not failed */
fd = tac_connect_single(tac_srv[srv_i].addr, tac_srv[srv_i].key,
tac_src_addr_info, __vrfname);
}
if (fd < 0) {
pam_syslog(pamh, LOG_ERR, "connection to srv[%d] %s failed: %m",
srv_i, tac_srv[srv_i].addr ?
tac_ntop(tac_srv[srv_i].addr->ai_addr) : "not set");
active_server.addr = NULL;
continue;
}
talk_tac_server(ctrl, fd, user, pass, tty, r_addr, attr, sptr,
reply, pamh);
if (*sptr == PAM_SUCCESS || *sptr == PAM_AUTH_ERR ||
*sptr == PAM_USER_UNKNOWN) {
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "%s: srv[%d] %s, pam_status=%d",
__func__, srv_i, tac_ntop(tac_srv[srv_i].addr->ai_addr),
*sptr);
if (*sptr == PAM_SUCCESS) {
if (active_server.addr == NULL) {
active_server.addr = tac_srv[srv_i].addr;
active_server.key = tac_srv[srv_i].key;
}
break;
}
/* else try other servers, if any. On errs, won't need fd */
}
if (active_server.addr) {
/*
* We connected, but got a failure, don't re-use, start
* over on next pass or connection attempt
*/
active_server.addr = NULL;
}
close(fd);
fd = -1;
}
*tacfd = fd;
}
/*
* We have to make a new connection each time, because libtac is single
* threaded (doesn't support multiple connects at the same time due to
* use of globals), and doesn't have support for persistent connections.
* That's fixable, but not worth the effort at this point.
*
* Trying to make this common code is ugly, but worth it to simplify
* maintenance and debugging.
*
* The problem is that the definition allows for multiple tacacs
* servers to be consulted, but a lot of the code was written such
* that once a server is found that responds, it keeps using it.
* That means when we are finding a server we need to do the full sequence.
* The related issue is that the lower level code can't communicate
* with multiple servers at the same time, and can't keep a connection
* open.
*
* TODO: Really should have a structure to pass user, pass, tty, and r_addr
* around everywhere.
*/
static int do_tac_connect(int ctrl, char *user, char *pass,
char *tty, char *r_addr, struct tac_attrib **attr,
struct areply *reply, pam_handle_t * pamh) {
int status = PAM_AUTHINFO_UNAVAIL, fd;
if (active_server.addr == NULL) { /* find a server with the info we want */
find_tac_server(ctrl, &fd, user, pass, tty, r_addr, attr, &status,
reply, pamh);
}
else { /* connect to the already chosen server, so we get
* consistent results. */
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "%s: use previous server %s", __func__,
tac_ntop(active_server.addr->ai_addr));
fd = tac_connect_single(active_server.addr, active_server.key,
tac_src_addr_info, __vrfname);
if (fd < 0)
pam_syslog(pamh, LOG_ERR, "reconnect failed to %s: %m",
tac_ntop(active_server.addr->ai_addr));
else
talk_tac_server(ctrl, fd, user, pass, tty, r_addr, attr, &status,
reply, pamh);
}
/*
* this is debug because we can get called for any user for
* commands like sudo, not just tacacs users, so it's not an
* error to fail here. The caller can handle the logging.
*/
if ((ctrl & PAM_TAC_DEBUG) && status != PAM_SUCCESS &&
status != PAM_USER_UNKNOWN)
pam_syslog(pamh, LOG_DEBUG, "no more servers to connect");
if (fd != -1)
close(fd); /* acct caller doesn't need connection */
return status;
}
/* Main PAM functions */
/* authenticates user on remote TACACS+ server
* returns PAM_SUCCESS if the supplied username and password
* pair is valid
* First check to see if the user is known to the server(s),
* so we don't go through the password phase for unknown
* users, and can return PAM_USER_UNKNOWN to the process.
*/
PAM_EXTERN
int pam_sm_authenticate (pam_handle_t * pamh, int flags,
int argc, const char **argv) {
int ctrl, retval;
char *user, *puser;
char *pass;
char *tty;
char *r_addr;
int status;
struct tac_attrib **attr, *attr_s = NULL;
priv_level = 0;
user = pass = tty = r_addr = NULL;
ctrl = _pam_parse(pamh, argc, argv);
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "%s: called (pam_tacplus v%u.%u.%u)",
__func__, PAM_TAC_VMAJ, PAM_TAC_VMIN, PAM_TAC_VPAT);
/* reset static state in case we are re-entered */
_reset_saved_user(pamh, ctrl & PAM_TAC_DEBUG);
/*
* If a mapped user entry already exists, we are probably being
* used for su or sudo, so we need to get the original user password,
* rather than the mapped user.
* Decided based on auid != uid and then do the lookup, similar to
* find_pw_user() in nss_tacplusc
*/
_pam_get_user(pamh, &puser);
user = get_user_to_auth(puser);
if (user == NULL)
return PAM_USER_UNKNOWN;
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "%s: user [%s] obtained", __func__, user);
_pam_get_terminal(pamh, &tty);
if (!strncmp(tty, "/dev/", 5))
tty += 5;
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "%s: tty [%s] obtained", __func__, tty);
_pam_get_rhost(pamh, &r_addr);
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "%s: rhost [%s] obtained", __func__,
r_addr);
/*
* Since these attributes are just for validating that the user is known to
* at least one server, it doesn't really matter whether these are "correct"
*/
attr = &attr_s;
tac_add_attrib(attr, "service", tac_service?tac_service:"shell");
tac_add_attrib(attr, "protocol", tac_protocol?tac_protocol:"ssh");
tac_add_attrib(attr, "cmd", "");
status = do_tac_connect(ctrl, user, NULL, tty, r_addr, &attr_s, NULL, pamh);
tac_free_attrib(&attr_s);
if (status != PAM_SUCCESS) {
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "TACACS+ user [%s] unknown,"
" (pam status=%d)", user, status);
goto err;
}
retval = tacacs_get_password (pamh, flags, ctrl, &pass);
if (retval != PAM_SUCCESS || pass == NULL || *pass == '\0') {
pam_syslog(pamh, LOG_ERR, "unable to obtain password");
status = PAM_CRED_INSUFFICIENT;
goto err;
}
retval = pam_set_item (pamh, PAM_AUTHTOK, pass);
if (retval != PAM_SUCCESS) {
pam_syslog(pamh, LOG_ERR, "unable to set password");
status = PAM_CRED_INSUFFICIENT;
goto err;
}
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "%s: password obtained", __func__);
status = do_tac_connect(ctrl, user, pass, tty, r_addr, NULL, NULL, pamh);
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "%s: exit with pam status: %d", __func__,
status);
err:
if (user && user != puser)
free(user); /* it was stdrup'ed */
if (NULL != pass) {
bzero(pass, strlen (pass));
free(pass);
}
return status;
} /* pam_sm_authenticate */
/* no-op function to satisfy PAM authentication module */
PAM_EXTERN
int pam_sm_setcred (pam_handle_t * pamh, int flags,
int argc, const char **argv) {
int ctrl = _pam_parse (pamh, argc, argv);
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "%s: called (pam_tacplus v%u.%u.%u)",
__func__, PAM_TAC_VMAJ, PAM_TAC_VMIN, PAM_TAC_VPAT);
return PAM_SUCCESS;
} /* pam_sm_setcred */
/* authorizes user on remote TACACS+ server, i.e. checks
* his permission to access requested service
* returns PAM_SUCCESS if the service is allowed
*/
PAM_EXTERN
int pam_sm_acct_mgmt (pam_handle_t * pamh, int flags,
int argc, const char **argv) {
int ctrl, status=PAM_AUTH_ERR;
char *user;
char *tty;
char *r_addr;
struct areply arep;
struct tac_attrib *attr_s = NULL, *attr;
user = tty = r_addr = NULL;
memset(&arep, 0, sizeof(arep));
/* this also obtains service name for authorization
this should be normally performed by pam_get_item(PAM_SERVICE)
but since PAM service names are incompatible TACACS+
we have to pass it via command line argument until a better
solution is found ;) */
ctrl = _pam_parse (pamh, argc, argv);
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "%s: called (pam_tacplus v%u.%u.%u)",
__func__, PAM_TAC_VMAJ, PAM_TAC_VMIN, PAM_TAC_VPAT);
_pam_get_user(pamh, &user);
if (user == NULL)
return PAM_USER_UNKNOWN;
_pam_get_terminal(pamh, &tty);
if(!strncmp(tty, "/dev/", 5))
tty += 5;
_pam_get_rhost(pamh, &r_addr);
/* checks for specific data required by TACACS+, which should
be supplied in pam module command line */
if(!*tac_service) {
pam_syslog(pamh, LOG_ERR, "TACACS+ service type not configured");
return PAM_AUTHINFO_UNAVAIL;
}
tac_add_attrib(&attr_s, "service", tac_service);
if(tac_protocol != NULL && tac_protocol[0] != '\0')
tac_add_attrib(&attr_s, "protocol", tac_protocol);
else
pam_syslog(pamh, LOG_ERR, "TACACS+ protocol type not configured"
" (IGNORED)");
tac_add_attrib(&attr_s, "cmd", "");
memset(&arep, 0, sizeof arep);
/*
* Check if user is authorized, independently of authentication.
* Authentication may have happened via ssh public key, rather than
* via TACACS+. PAM should not normally get to this entry point if
* user is not yet authenticated.
* We only write the mapping entry (if needed) when authorization
* is succesful.
* attr is not used here, but having a non-NULL value is how
* talk_tac_server() distinguishes that it is an acct call, vs auth
* TODO: use a different mechanism
*/
status = do_tac_connect(ctrl, user, NULL, tty, r_addr, &attr_s,
&arep, pamh);
tac_free_attrib(&attr_s);
if(active_server.addr == NULL) {
/* we need to return PAM_AUTHINFO_UNAVAIL here, rather than
* PAM_AUTH_ERR, or we can't use "ignore" or auth_err=bad in the
* pam configuration
*/
status = PAM_AUTHINFO_UNAVAIL;
goto cleanup;
}
if(status) {
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_NOTICE, "No TACACS mapping for %s after auth"
" failure", user);
goto cleanup;
}
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "%s: user [%s] successfully authorized",
__func__, user);
attr = arep.attr;
while (attr != NULL) {
const int new_len = attr->attr_len+1; /* 1 longer for terminating 0 */
char attribute[new_len];
char value[new_len];
char attrenv[new_len];
char tmpstr[new_len];
char *sep;
snprintf(tmpstr, sizeof tmpstr, "%*s", attr->attr_len,attr->attr);
sep = index(tmpstr, '=');
if(sep == NULL)
sep = index(tmpstr, '*');
if(sep != NULL) {
*sep = '\0';
snprintf(attribute, sizeof attribute, "%s", tmpstr);
snprintf(value, sizeof value, "%s", ++sep);
size_t i;
for (i = 0; attribute[i] != '\0'; i++) {
attribute[i] = toupper(attribute[i]);
if (attribute[i] == '-')
attribute[i] = '_';
}
if (ctrl & PAM_TAC_DEBUG)
pam_syslog(pamh, LOG_DEBUG, "%s: returned attribute `%s(%s)'"
" from server", __func__, attribute, value);
if(strncmp(attribute, "PRIV", 4) == 0) {
char *ok;
priv_level = (unsigned)strtoul(value, &ok, 0);
/* if this fails, we leave priv_level at 0, which is
* least privileged, so that's OK, but at least report it
*/
if (ok == value)
pam_syslog(pamh, LOG_WARNING,
"%s: non-numeric privilege for %s, got (%s)",
__func__, attribute, value);
}
/*
* make returned attributes available for other PAM modules via PAM
* environment. Since separator can be = or *, ensure it's = for
* the env.
*/
snprintf(attrenv, sizeof attrenv, "%s=%s", attribute, value);
if (pam_putenv(pamh, attrenv) != PAM_SUCCESS)
pam_syslog(pamh, LOG_WARNING, "%s: unable to set PAM"
" environment (%s)", __func__, attribute);
} else {
pam_syslog(pamh, LOG_WARNING, "%s: invalid attribute `%s',"
" no separator", __func__, attr->attr);
}
attr = attr->next;
}
update_mapped(pamh, user, priv_level, r_addr);
cleanup:
/* free returned attributes */
if(arep.attr != NULL)
tac_free_attrib(&arep.attr);
if(arep.msg != NULL)
free (arep.msg);
return status;
} /* pam_sm_acct_mgmt */
/*
* accounting packets may be directed to any TACACS+ server,
* independent from those used for authentication and authorization;
* they may be also directed to all specified servers
*/
static short unsigned int session_taskid;
/*
* send START accounting request to the remote TACACS+ server
* returns PAM error only if the request was refused or there
* were problems connection to the server
* sets sess_taskid so it can be used in close_session, so that
* accounting start and stop records have the same task_id, as
* the specification requires.
*/
PAM_EXTERN
int pam_sm_open_session (pam_handle_t * pamh, int flags,
int argc, const char **argv) {
if (!task_id)
#if defined(HAVE_OPENSSL_RAND_H) && defined(HAVE_LIBCRYPTO)
RAND_pseudo_bytes((unsigned char *) &task_id, sizeof(task_id));
#else
task_id=(short int) tac_magic();
#endif
session_taskid = task_id;
return _pam_account(pamh, argc, argv, TAC_PLUS_ACCT_FLAG_START, NULL);
} /* pam_sm_open_session */
/* sends STOP accounting request to the remote TACACS+ server
* returns PAM error only if the request was refused or there
* were problems connection to the server
*/
PAM_EXTERN
int pam_sm_close_session (pam_handle_t * pamh, int flags,
int argc, const char **argv) {
int rc;
char *user;