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support.c
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support.c
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/* support.c - support functions for pam_tacplus.c
*
* Copyright (C) 2010, Pawel Krawczyk <pawel.krawczyk@hush.com> and
* Jeroen Nijhof <jeroen@jeroennijhof.nl>
* Copyright 2016, 2017 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.
*/
#define PAM_SM_AUTH
#define PAM_SM_ACCOUNT
#define PAM_SM_SESSION
#define PAM_SM_PASSWORD
#include "support.h"
#include "jwt_util.h"
#include "pam_tacplus.h"
#include <stdlib.h>
#include <string.h>
#include <pwd.h>
#include <errno.h>
#include <fcntl.h>
#include <ctype.h>
#include <signal.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <tacplus/map_tacplus_user.h>
tacplus_server_t tac_srv[TAC_PLUS_MAXSERVERS];
extern tacplus_server_t active_server;
int tac_srv_no = 0;
static int tac_key_no;
static int debug; /* so we don't need to get from pam */
char tac_service[64];
char tac_protocol[64];
char tac_prompt[64];
char *__vrfname;
unsigned tac_use_tachome;
void _pam_log(int err, const char *format,...) {
char msg[256];
va_list args;
va_start(args, format);
vsnprintf(msg, sizeof(msg), format, args);
openlog("PAM-tacplus", LOG_PID, LOG_AUTH);
syslog(err, "%s", msg);
va_end(args);
closelog();
}
#include <utmpx.h>
/* original name passed in via PAM; this makes this library not usable for
* multiple calls for different users, but that should be OK for PAM. That's
* handled by calling _reset_saved_user from pam_sm_open_session()
*/
static char orig_user[__UT_NAMESIZE];
/* used when we have a persistent connection */
void _reset_saved_user(int debug)
{
if (*orig_user && debug)
_pam_log(LOG_DEBUG, "re-entered, clearing saved userid=%s", orig_user);
*orig_user = 0;
}
/* These functions return static info, overwritten on subsequent calls.
* Since orig_user is static global, we aren't multi-threaded, but can
* handle multiple users, as log as pam_sm_open_session is called for
* each, because we'll call _reset_saved_user() to clear.
*/
void _pam_get_user(pam_handle_t *pamh, char **user) {
int retval;
if (!user)
return;
if (*orig_user) {
*user = orig_user; /* never our modified user */
return;
}
retval = pam_get_user(pamh, (void *)user, "Username: ");
if (retval != PAM_SUCCESS || *user == NULL || **user == '\0') {
_pam_log(LOG_ERR, "unable to obtain username");
*user = NULL;
}
else
strncpy(orig_user, *user, sizeof (orig_user)-1);
}
/* These functions return static info, overwritten on subsequent calls. */
void _pam_get_terminal(pam_handle_t *pamh, char **tty) {
int retval;
if (!tty)
return;
retval = pam_get_item(pamh, PAM_TTY, (void *)tty);
if (retval != PAM_SUCCESS || *tty == NULL || **tty == '\0') {
*tty = ttyname(STDIN_FILENO);
if(*tty == NULL || **tty == '\0')
*tty = "unknown";
}
}
/* These functions return static info, overwritten on subsequent calls. */
void _pam_get_rhost(pam_handle_t *pamh, char **rhost) {
int retval;
if (!rhost)
return;
retval = pam_get_item(pamh, PAM_RHOST, (void *)rhost);
if (retval != PAM_SUCCESS || *rhost == NULL || **rhost == '\0') {
*rhost = "unknown";
}
}
int converse(pam_handle_t * pamh, int nargs, const struct pam_message *message,
struct pam_response **response) {
int retval;
struct pam_conv *conv;
if ((retval = pam_get_item (pamh, PAM_CONV, (const void **)&conv)) ==
PAM_SUCCESS) {
retval = conv->conv(nargs, &message, response, conv->appdata_ptr);
if (retval != PAM_SUCCESS) {
_pam_log(LOG_ERR, "(pam_tacplus) converse returned %d", retval);
_pam_log(LOG_ERR, "that is: %s", pam_strerror (pamh, retval));
}
} else {
_pam_log (LOG_ERR, "(pam_tacplus) converse failed to get pam_conv");
}
return retval;
}
/* stolen from pam_stress */
int tacacs_get_password (pam_handle_t * pamh, int flags
,int ctrl, char **password) {
const void *pam_pass;
char *pass = NULL;
if (ctrl & PAM_TAC_DEBUG)
syslog (LOG_DEBUG, "%s: called", __func__);
if ( (ctrl & (PAM_TAC_TRY_FIRST_PASS | PAM_TAC_USE_FIRST_PASS))
&& (pam_get_item(pamh, PAM_AUTHTOK, &pam_pass) == PAM_SUCCESS)
&& (pam_pass != NULL) ) {
if ((pass = strdup(pam_pass)) == NULL)
return PAM_BUF_ERR;
} else if ((ctrl & PAM_TAC_USE_FIRST_PASS)) {
_pam_log(LOG_WARNING, "no forwarded password");
return PAM_PERM_DENIED;
} else {
struct pam_message msg;
struct pam_response *resp = NULL;
int retval;
/* set up conversation call */
msg.msg_style = PAM_PROMPT_ECHO_OFF;
if (!tac_prompt[0]) {
msg.msg = "Password: ";
} else {
msg.msg = tac_prompt;
}
if ((retval = converse (pamh, 1, &msg, &resp)) != PAM_SUCCESS)
return retval;
if (resp != NULL) {
if (resp->resp == NULL && (ctrl & PAM_TAC_DEBUG))
_pam_log (LOG_DEBUG, "%s: NULL authtok given", __func__);
pass = resp->resp; /* remember this! */
resp->resp = NULL;
free(resp);
resp = NULL;
} else {
if (ctrl & PAM_TAC_DEBUG) {
_pam_log (LOG_DEBUG, "pam_sm_authenticate: no error reported");
_pam_log (LOG_DEBUG, "getting password, but NULL returned!?");
}
return PAM_CONV_ERR;
}
}
/*
FIXME *password can still turn out as NULL
and it can't be free()d when it's NULL
*/
*password = pass; /* this *MUST* be free()'d by this module */
if(ctrl & PAM_TAC_DEBUG)
syslog(LOG_DEBUG, "%s: obtained password", __func__);
return PAM_SUCCESS;
}
static int parse_argfile(const char *);
/*
* parse arguments, one at a time. Separate routine
* so we can have arguments in include files, and use
* common code.
*/
static int parse_arg(const char *arg) {
int ctrl = 0;
if(!strncmp (arg, "include=", 8)) {
/*
* allow include files, useful for centralizing tacacs
* server IP address and secret.
*/
if(arg[8]) /* else treat as empty config */
ctrl |= parse_argfile(arg + 8);
}
else if (!strcmp (arg, "debug")) { /* all */
ctrl |= PAM_TAC_DEBUG;
} else if (!strncmp (arg, "debug=", 6)) { /* allow debug=Digits also */
unsigned val = (unsigned)strtoul(arg+6, NULL, 0);
if (val)
ctrl |= PAM_TAC_DEBUG;
} else if (!strcmp (arg, "use_first_pass")) {
ctrl |= PAM_TAC_USE_FIRST_PASS;
} else if (!strcmp (arg, "try_first_pass")) {
ctrl |= PAM_TAC_TRY_FIRST_PASS;
} else if (!strncmp (arg, "service=", 8)) { /* author & acct */
tac_xstrcpy (tac_service, arg + 8, sizeof(tac_service));
} else if (!strncmp (arg, "protocol=", 9)) { /* author & acct */
tac_xstrcpy (tac_protocol, arg + 9, sizeof(tac_protocol));
} else if (!strncmp (arg, "prompt=", 7)) { /* authentication */
tac_xstrcpy (tac_prompt, arg + 7, sizeof(tac_prompt));
/* Replace _ with space */
int chr;
for (chr = 0; chr < strlen(tac_prompt); chr++) {
if (tac_prompt[chr] == '_') {
tac_prompt[chr] = ' ';
}
}
} else if (!strncmp (arg, "login=", 6)) {
tac_xstrcpy (tac_login, arg + 6, sizeof(tac_login));
} else if (!strncmp (arg, "user_homedir=", 13)) {
tac_use_tachome = strtoul(arg+13, NULL, 0);
} else if (!strcmp (arg, "acct_all")) {
ctrl |= PAM_TAC_ACCT;
} else if (!strncmp (arg, "server=", 7)) { /* authen & acct */
if(tac_srv_no < TAC_PLUS_MAXSERVERS) {
struct addrinfo hints, *servers, *server;
int rv;
char *close_bracket, *server_name, *port, server_buf[256];
memset(&hints, 0, sizeof hints);
hints.ai_family = AF_UNSPEC; /* use IPv4 or IPv6, whichever */
hints.ai_socktype = SOCK_STREAM;
if (strlen(arg + 7) >= sizeof(server_buf)) {
_pam_log(LOG_ERR, "server address too long, sorry");
goto done;
}
strcpy(server_buf, arg + 7);
if (*server_buf == '[' &&
(close_bracket = strchr(server_buf, ']')) != NULL) {
/* Check for URI syntax */
server_name = server_buf + 1;
port = strchr(close_bracket, ':');
*close_bracket = '\0';
} else { /* Fall back to traditional syntax */
server_name = server_buf;
port = strchr(server_buf, ':');
}
if (port != NULL) {
*port = '\0';
port++;
}
if ((rv = getaddrinfo(server_name, (port == NULL) ? "49" : port,
&hints, &servers)) == 0) {
for(server = servers; server != NULL &&
tac_srv_no < TAC_PLUS_MAXSERVERS;
server = server->ai_next) {
tac_srv[tac_srv_no].addr = server;
/* use current key, if our index not yet set */
if(tac_key_no && !tac_srv[tac_srv_no].key)
tac_srv[tac_srv_no].key =
tac_xstrdup(tac_srv[tac_key_no-1].key);
tac_srv_no++;
}
} else {
_pam_log (LOG_ERR,
"skip invalid server: %s (getaddrinfo: %s)",
server_name, gai_strerror(rv));
}
} else {
_pam_log(LOG_ERR, "maximum number of servers (%d) exceeded,"
" skipping", TAC_PLUS_MAXSERVERS);
}
} else if (!strncmp (arg, "secret=", 7)) {
int i;
/* no need to complain if too many on this one */
if(tac_key_no < TAC_PLUS_MAXSERVERS) {
if((tac_srv[tac_key_no].key = tac_xstrdup(arg+7)))
tac_key_no++;
else
_pam_log(LOG_ERR, "%s: unable to copy server secret %d: %m",
tac_key_no);
}
/* if 'secret=' was given after a 'server=' parameter,
* fill in any unset keys up to current server number. */
for(i = tac_srv_no-1; i >= 0; i--) {
if (tac_srv[i].key)
continue;
tac_srv[i].key = tac_xstrdup(arg + 7);
}
} else if (!strncmp (arg, "timeout=", 8)) {
/* FIXME atoi() doesn't handle invalid numeric strings well */
tac_timeout = atoi(arg + 8);
if (tac_timeout < 0) {
tac_timeout = 0;
} else {
tac_readtimeout_enable = 1;
}
} else if(!strncmp(arg, "vrf=", 4)) {
__vrfname = tac_xstrdup(arg + 4);
} else {
_pam_log (LOG_WARNING, "unrecognized option: %s", arg);
}
done:
debug = ctrl & PAM_TAC_DEBUG;
return ctrl;
}
static int parse_argfile(const char *file) {
FILE *conf;
char lbuf[256];
int ctrl = 0;
conf = fopen(file, "r");
if(conf == NULL) {
_pam_log(LOG_ERR, "Unable to open config file %s: %m", file);
return 0;
}
while (fgets(lbuf, sizeof lbuf, conf)) {
if(*lbuf == '#' || isspace(*lbuf))
continue; /* skip comments, white space lines, etc. */
strtok(lbuf, " \t\n\r\f"); /* terminate buffer at first whitespace */
ctrl |= parse_arg(lbuf);
}
fclose(conf);
return ctrl;
}
/*
* This has to re-parse every time, because we can have different parameters
* For different pam.d files.
*/
int _pam_parse (int argc, const char **argv) {
int i, ctrl = 0;
/*
* Because we can be called multiple times, we need to reset the state
* each time we go through this function. We need to free allocated
* memory to avoid memory leaks.
*/
for(i = 0; i<tac_key_no; i++)
if (tac_srv[i].key)
free(tac_srv[i].key);
memset(tac_srv, 0, sizeof(tacplus_server_t) * TAC_PLUS_MAXSERVERS);
active_server.addr = NULL; /* be sure no refs into freed mem */
tac_key_no = 0;
tac_srv_no = 0;
tac_service[0] = 0;
tac_protocol[0] = 0;
tac_prompt[0] = 0;
tac_login[0] = 0;
for (ctrl = 0; argc-- > 0; ++argv)
ctrl |= parse_arg(*argv);
if (ctrl & PAM_TAC_DEBUG) {
int n;
_pam_log(LOG_DEBUG, "%d servers defined", tac_srv_no);
for(n = 0; n < tac_srv_no; n++) {
_pam_log(LOG_DEBUG, "server[%d] { addr=%s, key='%s' }",
n, tac_ntop(tac_srv[n].addr->ai_addr), tac_srv[n].key);
}
_pam_log(LOG_DEBUG, "tac_service='%s'", tac_service);
_pam_log(LOG_DEBUG, "tac_protocol='%s'", tac_protocol);
_pam_log(LOG_DEBUG, "tac_prompt='%s'", tac_prompt);
_pam_log(LOG_DEBUG, "tac_login='%s'", tac_login);
}
return ctrl;
} /* _pam_parse */
/*
* when login is successful (from pam account entry point, after authorization
* succeeds), update our local mapping data, and if we are using the tacacs
* username in the home directory, create the home directory if needed (using
* the mkhomedir_helper program). The code to exec mkhomedir_helper is based on
* pam_mkhomedir.c
*/
void update_mapped(pam_handle_t *pamh, char *user, unsigned level, char *rhost)
{
struct passwd *pw;
struct stat st;
int rc, retval, child, restore = 0;
struct sigaction newsa, oldsa;
const char *path = "/sbin/mkhomedir_helper";
if (!update_mapuser(user, level, rhost, user, tac_use_tachome))
return;
/*
* if we mapped the user name, set SUDO_PROMPT in env so that
* it prompts as the login user, not the mapped user, unless (unlikely)
* the prompt has already been set. Set SUDO_USER as well, for
* consistency.
*/
if (!pam_getenv(pamh, "SUDO_PROMPT")) {
char nprompt[strlen("SUDO_PROMPT=[sudo] password for ") +
strlen(user) + 3]; /* + 3 for ": " and the \0 */
snprintf(nprompt, sizeof nprompt,
"SUDO_PROMPT=[sudo] password for %s: ", user);
if (pam_putenv(pamh, nprompt) != PAM_SUCCESS)
_pam_log(LOG_NOTICE, "failed to set PAM sudo prompt (%s)",
nprompt);
}
if (!pam_getenv(pamh, "SUDO_USER")) {
char sudouser[strlen("SUDO_USER=") +
strlen(user) + 1]; /* + 1 for the \0 */
snprintf(sudouser, sizeof sudouser,
"SUDO_USER=%s", user);
if (pam_putenv(pamh, sudouser) != PAM_SUCCESS)
_pam_log(LOG_NOTICE, "failed to set PAM sudo user (%s)",
sudouser);
}
if (!tac_use_tachome)
return;
pw = getpwnam(user); /* this should never fail, at this point... */
if (!pw) {
_pam_log(LOG_NOTICE, "Unable to get passwd entry for user (%s)", user);
return;
}
if (stat(pw->pw_dir, &st) == 0)
return;
if (debug)
_pam_log(LOG_NOTICE, "creating home directory %s for user %s",
pw->pw_dir, user);
/*
* This code arranges that the demise of the child does not cause
* the application to receive a signal it is not expecting - which
* may kill the application or worse. Based on pam_mkhomedir.c
*/
memset(&newsa, '\0', sizeof(newsa));
newsa.sa_handler = SIG_DFL;
if (sigaction(SIGCHLD, &newsa, &oldsa) == 0)
restore = 1;
child = fork();
if(child == -1) {
_pam_log(LOG_ERR, "fork to exec %s %s failed: %m", path, user);
return;
}
if(child == 0) {
execl(path, path, user, NULL);
_pam_log(LOG_ERR, "exec %s %s failed: %m", path, user);
exit(1);
}
while ((rc=waitpid(child, &retval, 0)) < 0 && errno == EINTR)
;
if(rc < 0)
_pam_log(LOG_ERR, "waitpid for exec of %s %s failed: %m", path,
user);
else if(!WIFEXITED(retval))
_pam_log(LOG_ERR, "%s %s abnormal exit: 0x%x", retval);
else {
retval = WEXITSTATUS(retval);
if(retval)
_pam_log(LOG_ERR, "%s %s abnormal exit: %d", path, user,
retval);
}
if (restore)
sigaction(SIGCHLD, &oldsa, NULL);
}
/*
* Create rtbick-token upon user login
*
*/
void
pam_create_rtb_token(pam_handle_t *pamh)
{
char attrenv[1024] = {0};
const char *token = NULL;
token = jwt_create_token(pamh);
snprintf(attrenv,1024, "RTB_TOKEN=%s",token);
if (pam_putenv(pamh, attrenv) != PAM_SUCCESS) {
_pam_log(LOG_ERR, "token creation- Failed to stored in environment");
}
}