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nss_tacplus.c
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nss_tacplus.c
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/*
* Copyright (C) 2014, 2015, 2016, 2017, 2018, 2019 Cumulus Networks, Inc.
* All rights reserved.
* Author: Dave Olson <[email protected]>
*
* 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.
*/
/*
* This plugin implements getpwnam_r for NSS over TACACS+
* and implements getpwuid_r for UIDs if and only if a mapped
* TACACS+ user is currently logged in (libtacplus_map)
* This means that if you do, e.g.: ls -ld ~tacacs15, you will
* sometimes get a mapped username, and other times get tacacs15,
* depending on whether a mapped user is logged in or not.
*/
#include <string.h>
#include <syslog.h>
#include <stdbool.h>
#include <stdlib.h>
#include <pwd.h>
#include <errno.h>
#include <fcntl.h>
#include <ctype.h>
#include <nss.h>
#include <libaudit.h>
#include <stddef.h>
#include <grp.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <tacplus/libtac.h>
#include <tacplus/map_tacplus_user.h>
#include "nss_tacplus.h"
static const char *nssname = "nss_tacplus"; /* for syslogs */
static const char *config_file = "/etc/tacplus_nss.conf";
/*
* pwbuf is used to reduce number of arguments passed around; the strings in
* the passwd struct need to point into this buffer.
*/
struct pwbuf {
char *name;
char *buf;
struct passwd *pw;
int *errnop;
size_t buflen;
};
typedef struct {
struct addrinfo *addr;
char *key;
unsigned not_resp;
} tacplus_server_t;
/* set from configuration file parsing */
static tacplus_server_t tac_srv[TAC_PLUS_MAXSERVERS];
static int tac_srv_no, tac_key_no;
static char tac_service[] = "shell";
static char tac_protocol[] = "ssh";
static char tac_rhost[INET6_ADDRSTRLEN];
static char vrfname[64];
static char *exclude_users;
static uid_t min_uid = ~0U; /* largest possible */
static int debug;
static int printed_srvs;
static uint16_t use_tachome;
static int conf_parsed = 0;
static struct sockaddr src_sockaddr;
static struct addrinfo src_addr_info;
static struct addrinfo *src_addr;
static void get_remote_addr(void);
#define MAX_INCL 8 /* max config level nesting */
/* reset all config variables when we are going to re-parse */
static void
reset_config(void)
{
int i, nservers;
/* reset the config variables that we use, freeing memory where needed */
nservers = tac_srv_no;
tac_srv_no = 0;
tac_key_no = 0;
vrfname[0] = '\0';
if(exclude_users) {
(void)free(exclude_users);
exclude_users = NULL;
}
debug = 0;
printed_srvs = 0;
use_tachome = 0;
tac_timeout = 0;
min_uid = ~0U;
src_addr = NULL;
for(i = 0; i < nservers; i++) {
if(tac_srv[i].key) {
free(tac_srv[i].key);
tac_srv[i].key = NULL;
}
tac_srv[i].addr = NULL;
tac_srv[i].not_resp = 0;
}
}
/* Convert ip address string to address info.
* It returns 0 on success, or -1 otherwise
* It supports ipv4 only.
*/
static int str_to_ipv4(const char *srcaddr, struct addrinfo *p_addr_info)
{
struct sockaddr_in *s_in;
s_in = (struct sockaddr_in *)p_addr_info->ai_addr;
s_in->sin_family = AF_INET;
s_in->sin_addr.s_addr = INADDR_ANY;
if (inet_pton(AF_INET, srcaddr, &(s_in->sin_addr)) == 1) {
p_addr_info->ai_family = AF_INET;
p_addr_info->ai_addrlen = sizeof (struct sockaddr_in);
return 0;
}
return -1;
}
static int nss_tacplus_config(int *errnop, const char *cfile, int top)
{
FILE *conf;
char lbuf[256];
static struct stat lastconf[MAX_INCL];
static char *cfilelist[MAX_INCL];
struct stat st, *lst;
if(top > MAX_INCL) {
syslog(LOG_NOTICE, "%s: Config file include depth > %d, ignoring %s",
nssname, MAX_INCL, cfile);
return 1;
}
lst = &lastconf[top-1];
if(conf_parsed && top == 1) {
/*
* check to see if the config file(s) have changed since last time,
* in case we are part of a long-lived daemon. If any changed,
* reparse. If not, return the appropriate status (err or OK)
* This is somewhat complicated by the include file mechanism.
* When we have nested includes, we have to check all the config
* files we saw previously, not just the top level config file.
*/
int i;
for(i=0; i < MAX_INCL; i++) {
struct stat *cst;
cst = &lastconf[i];
if(!cst->st_ino || !cfilelist[i]) /* end of files */
return conf_parsed == 2 ? 0 : 1;
if (stat(cfilelist[i], &st) || st.st_ino != cst->st_ino ||
st.st_mtime != cst->st_mtime || st.st_ctime != cst->st_ctime)
break; /* found removed or different file, so re-parse */
}
reset_config();
syslog(LOG_NOTICE, "%s: Configuration file(s) have changed, "
"re-initializing", nssname);
}
/* don't check for failures, we'll just skip, don't want to error out */
cfilelist[top-1] = strdup(cfile);
conf = fopen(cfile, "r");
if(conf == NULL) {
*errnop = errno;
if(!conf_parsed && debug) /* debug because privileges may not allow */
syslog(LOG_DEBUG, "%s: can't open config file %s: %m",
nssname, cfile);
return 1;
}
if (fstat(fileno(conf), lst) != 0)
memset(lst, 0, sizeof *lst); /* avoid stale data, no warning */
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 */
if(!strncmp(lbuf, "include=", 8)) {
/*
* allow include files, useful for centralizing tacacs
* server IP address and secret. When running non-privileged,
* may not be able to read one or more config files.
*/
if(lbuf[8])
(void)nss_tacplus_config(errnop, &lbuf[8], top+1);
}
else if(!strncmp(lbuf, "debug=", 6))
debug = strtoul(lbuf+6, NULL, 0);
else if (!strncmp (lbuf, "user_homedir=", 13))
use_tachome = (uint16_t)strtoul(lbuf+13, NULL, 0);
else if (!strncmp (lbuf, "timeout=", 8)) {
char *argend;
int val = (unsigned)strtol(lbuf+8, &argend, 0);
if (argend != (lbuf+8) && val >= 0) {
tac_timeout = val;
tac_readtimeout_enable = 1;
}
else
syslog(LOG_WARNING, "%s: invalid parameter value (%s)",
nssname, lbuf);
}
/*
* This next group is here to prevent a warning in the
* final "else" case. We don't need them, but if there
* is a common included file, we might see them.
*/
else if(!strncmp(lbuf, "service=", 8) ||
!strncmp(lbuf, "protocol=", 9) ||
!strncmp(lbuf, "login=", 6))
;
else if(!strncmp(lbuf, "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 = strdup(lbuf+7)))
tac_key_no++;
else
/* don't log the actual line, it's a security issue */
syslog(LOG_ERR, "%s: unable to copy server secret %d: %m",
nssname, tac_key_no);
}
/* handle case where 'secret=' was given after a 'server='
* parameter, fill in the current secret */
for(i = tac_srv_no-1; i >= 0; i--) {
if (tac_srv[i].key)
continue;
tac_srv[i].key = strdup(lbuf+7);
}
}
else if (!strncmp (lbuf, "source_ip=", 10)) {
const char *srcip = lbuf + 10;
/* if source ip address, convert it to addr info */
memset (&src_addr_info, 0, sizeof (struct addrinfo));
memset (&src_sockaddr, 0, sizeof (struct sockaddr));
src_addr_info.ai_addr = &src_sockaddr;
if (str_to_ipv4 (srcip, &src_addr_info) == 0)
src_addr = &src_addr_info;
else {
src_addr = NULL; /* for re-parsing or errors */
syslog(LOG_WARNING,
"%s: unable to convert %s to an IPv4 address", nssname,
lbuf);
}
}
else if(!strncmp(lbuf, "exclude_users=", 14)) {
/*
* Don't lookup users in this comma-separated list for both
* robustness and performnce. Typically root and other commonly
* used local users. If set, we also look up the uids
* locally, and won't do remote lookup on those uids either.
*/
exclude_users = strdup(lbuf+14);
}
else if(!strncmp(lbuf, "min_uid=", 8)) {
/*
* Don't lookup uids that are local, typically set to either
* 0 or smallest always local user's uid
*/
unsigned long uid;
char *valid;
uid = strtoul(lbuf+8, &valid, 0);
if (valid > (lbuf+8))
min_uid = (uid_t)uid;
}
else if(!strncmp(lbuf, "vrf=", 4))
strncpy(vrfname, lbuf + 4, sizeof(vrfname));
else if(!strncmp(lbuf, "server=", 7)) {
if(tac_srv_no < TAC_PLUS_MAXSERVERS) {
struct addrinfo hints, *servers, *server;
int rv;
char *port, server_buf[sizeof lbuf];
memset(&hints, 0, sizeof hints);
hints.ai_family = AF_UNSPEC; /* use IPv4 or IPv6, whichever */
hints.ai_socktype = SOCK_STREAM;
strcpy(server_buf, lbuf + 7);
port = strchr(server_buf, ':');
if(port != NULL) {
*port = '\0';
port++;
}
if((rv = getaddrinfo(server_buf, (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 =
strdup(tac_srv[tac_key_no-1].key);
tac_srv_no++;
}
}
else {
syslog(LOG_ERR,
"%s: skip invalid server: %s (getaddrinfo: %s)",
nssname, server_buf, gai_strerror(rv));
}
}
else {
syslog(LOG_WARNING, "%s: maximum number of servers (%d) "
"exceeded, skipping", nssname, TAC_PLUS_MAXSERVERS);
}
}
else if(debug) /* ignore unrecognized lines, unless debug on */
/* Don't complain about acct_all, may be set in shared
* config, even if we don't use it.
*/
if(strncmp(lbuf, "acct_all=", 9))
syslog(LOG_WARNING, "%s: unrecognized parameter: %s",
nssname, lbuf);
}
fclose(conf);
return 0;
}
/* common get config code at each entry point */
static int
get_config(int *errp, int level)
{
int result = nss_tacplus_config(errp, config_file, 1);
conf_parsed = result == 0 ? 2 : 1;
get_remote_addr();
/* no config file, no servers, etc.
* this is a debug because privileges may not allow access
* for included files.
*/
if(debug && result)
syslog(LOG_DEBUG, "%s: bad config or server line for nss_tacplus",
nssname);
return result;
}
/*
* Separate function so we can print first time we try to connect,
* rather than during config.
* Don't print at config, because often the uid lookup is one we
* skip due to min_uid, so no reason to clutter the log.
*/
static void print_servers(void)
{
int n;
if (printed_srvs || !debug)
return;
printed_srvs = 1;
if(tac_srv_no == 0)
syslog(LOG_DEBUG, "%s:%s: no TACACS %s in config (or no permission),"
" giving up",
nssname, __FUNCTION__, tac_srv_no ? "service" :
(*tac_service ? "server" : "service and no server"));
/* do not log tac_srv[n].key; it's a security issue */
for(n = 0; n < tac_srv_no; n++)
syslog(LOG_DEBUG, "%s: server[%d] { addr=%s }", nssname,
n, tac_srv[n].addr ? tac_ntop(tac_srv[n].addr->ai_addr)
: "unknown");
}
/*
* copy a passwd structure and it's strings, using the provided buffer
* for the strings.
* if usename is non-NULL, use that, rather than pw_name in srcpw, so we can
* preserve the original requested name (this is part of the tacacs remapping).
* For strings, if pointer is null, use an empty string.
* Returns 0 if everything fit, otherwise 1.
*/
static int
pwcopy(char *buf, size_t len, struct passwd *srcpw, struct passwd *destpw,
const char *usename, uint16_t tachome)
{
int needlen, cnt, origlen = len;
char *shell;
if(!usename) {
usename = srcpw->pw_name;
tachome = 0; /* early lookups; no tachome */
}
needlen = usename ? strlen(usename) + 1 : 1 +
srcpw->pw_dir ? strlen(srcpw->pw_dir) + 1 : 1 +
srcpw->pw_gecos ? strlen(srcpw->pw_gecos) + 1 : 1 +
srcpw->pw_shell ? strlen(srcpw->pw_shell) + 1 : 1 +
srcpw->pw_passwd ? strlen(srcpw->pw_passwd) + 1 : 1;
if(needlen > len) {
if(debug)
syslog(LOG_DEBUG, "%s provided password buffer too small (%ld<%d)",
nssname, (long)len, needlen);
return 1;
}
destpw->pw_uid = srcpw->pw_uid;
destpw->pw_gid = srcpw->pw_gid;
cnt = snprintf(buf, len, "%s", usename ? usename : "");
destpw->pw_name = buf;
cnt++; /* allow for null byte also */
buf += cnt;
len -= cnt;
cnt = snprintf(buf, len, "%s", srcpw->pw_passwd ? srcpw->pw_passwd : "");
destpw->pw_passwd = buf;
cnt++;
buf += cnt;
len -= cnt;
cnt = snprintf(buf, len, "%s", srcpw->pw_shell ? srcpw->pw_shell : "");
destpw->pw_shell = buf;
shell = strrchr(buf, '/');
shell = shell ? shell+1 : buf;
if (tachome && *shell == 'r') {
tachome = 0;
if(debug > 1)
syslog(LOG_DEBUG, "%s tacacs login %s with user_homedir not allowed"
"; shell is %s", nssname, srcpw->pw_name, buf);
}
cnt++;
buf += cnt;
len -= cnt;
cnt = snprintf(buf, len, "%s", srcpw->pw_gecos ? srcpw->pw_gecos : "");
destpw->pw_gecos = buf;
cnt++;
buf += cnt;
len -= cnt;
if (tachome && usename) {
char *slash, dbuf[strlen(srcpw->pw_dir) + strlen(usename)];
snprintf(dbuf, sizeof dbuf, "%s", srcpw->pw_dir ? srcpw->pw_dir : "");
slash = strrchr(dbuf, '/');
if (slash) {
slash++;
snprintf(slash, sizeof dbuf - (slash-dbuf), "%s", usename);
}
cnt = snprintf(buf, len, "%s", dbuf);
}
else
cnt = snprintf(buf, len, "%s", srcpw->pw_dir ? srcpw->pw_dir : "");
destpw->pw_dir = buf;
cnt++;
len -= cnt;
if(len < 0) {
if(debug)
syslog(LOG_DEBUG, "%s provided password buffer too small (%ld<%d)",
nssname, (long)origlen, origlen-(int)len);
return 1;
}
return 0;
}
/*
* Find the username or the matching tacacs privilege user in /etc/passwd
* We use fgetpwent() so we can check the local file, always.
* This could cause problems if somebody is using local users, ldap, and tacacs,
* but we just require that the mapped user always be a local user. Since the
* local user password isn't supposed to be used, that should be OK.
*
* We shouldn't normally find the username, because tacacs lookup should be
* configured to follow local in nsswitch.conf, but somebody may configure the
* other way, so we look for both the given user, and our "matching" user name
* based on the tacacs authorization level.
*
* If not found, then try to map to a localuser tacacsN where N <= to the
* TACACS+ privilege level, using the APIs in libtacplus_map.so
* algorithm in update_mapuser(), but only considering tacacs users.
* Returns 0 on success, else 1
*/
static int
find_pw_userpriv(unsigned priv, struct pwbuf *pb)
{
FILE *pwfile;
struct passwd tpw, *ent;
int matches, ret, rett;
unsigned origpriv = priv;
char tbuf[pb->buflen];
char tacuser[9]; /* "tacacs" followed by 1-2 digits */
tacuser[0] = '\0';
pwfile = fopen("/etc/passwd", "r");
if(!pwfile) {
syslog(LOG_WARNING, "%s: failed to open /etc/passwd: %m", nssname);
return 1;
}
recheck:
snprintf(tacuser, sizeof tacuser, "tacacs%u", priv);
tpw.pw_name = NULL;
rett = 0;
for(matches=0; !matches && (ent = fgetpwent(pwfile)); ) {
if(ent->pw_name && !strcmp(ent->pw_name, tacuser)) {
rett = pwcopy(tbuf, sizeof(tbuf), ent, &tpw, NULL, use_tachome);
matches++;
}
}
if(!matches && priv > 0) {
priv--;
rewind(pwfile);
goto recheck;
}
ret = 1;
fclose(pwfile);
if(matches) {
if(priv != origpriv && debug)
syslog(LOG_DEBUG, "%s: local user not found at privilege=%u,"
" using %s", nssname, origpriv, tacuser);
if(tpw.pw_name && !rett) {
ret = pwcopy(pb->buf, pb->buflen, &tpw, pb->pw, pb->name,
use_tachome);
}
}
if(ret)
*pb->errnop = ERANGE;
return ret;
}
/*
* This is similar to find_pw_userpriv(), but passes in a fixed
* name for UID lookups, where we have the mapped name from the
* map file, so trying multiple tacacsN users would be wrong.
* Some commonality, but ugly to factor
* Only applies to mapped users
* returns 0 on success
*/
static int
find_pw_user(const char *logname, const char *tacuser, struct pwbuf *pb,
uint16_t usetachome)
{
FILE *pwfile;
struct passwd *ent;
int ret = 1;
if(!tacuser) {
if(debug)
syslog(LOG_DEBUG, "%s: passed null username, failing", nssname);
return 1;
}
pwfile = fopen("/etc/passwd", "r");
if(!pwfile) {
syslog(LOG_WARNING, "%s: failed to open /etc/passwd: %m",
nssname);
return 1;
}
pb->pw->pw_name = NULL; /* be paranoid */
for(ret = 1; ret && (ent = fgetpwent(pwfile)); ) {
if(!ent->pw_name)
continue; /* shouldn't happen */
if(!strcmp(ent->pw_name, tacuser)) {
ret = pwcopy(pb->buf, pb->buflen, ent, pb->pw, logname, usetachome);
break;
}
}
fclose(pwfile);
if(ret)
*pb->errnop = ERANGE;
return ret;
}
/*
* we got the user back. Go through the attributes, find their privilege
* level, map to the local user, fill in the data, etc.
* Returns 0 on success, 1 on errors.
*/
static int
got_tacacs_user(struct tac_attrib *attr, struct pwbuf *pb)
{
unsigned long priv_level = 0;
while(attr != NULL) {
/* we are looking for the privilege attribute, can be in several forms,
* typically priv-lvl= or priv_lvl= */
if(strncasecmp(attr->attr, "priv", 4) == 0) {
char *ok, *val;
for(val=attr->attr; *val && *val != '*' && *val != '='; val++)
;
if(!*val)
continue;
val++;
priv_level = strtoul(val, &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 == val && debug)
syslog(LOG_WARNING, "%s: non-numeric privilege for %s, (%s)",
nssname, pb->name, attr->attr);
}
attr = attr->next;
}
return find_pw_userpriv(priv_level, pb);
}
/*
* Attempt to connect to the requested tacacs server.
* Returns fd for connection, or -1 on failure
*/
static int
connect_tacacs(struct tac_attrib **attr, int srvr)
{
int fd;
fd = tac_connect_single(tac_srv[srvr].addr, tac_srv[srvr].key, src_addr,
vrfname[0]?vrfname:NULL);
if(fd >= 0) {
tac_add_attrib(attr, "service", tac_service);
if(tac_protocol[0])
tac_add_attrib(attr, "protocol", tac_protocol);
/* empty cmd is required, at least for linux tac_plus */
tac_add_attrib(attr, "cmd", "");
}
return fd;
}
/*
* 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;
}
}
/*
* lookup the user on a TACACS server. Returns 0 on successful lookup, else 1
*
* Make a new connection each time, because libtac is single threaded and
* 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.
* Step through all servers until success or end of list, because different
* servers can have different databases.
*/
static int
lookup_tacacs_user(struct pwbuf *pb)
{
struct areply arep;
int ret = 1, done = 0;
struct tac_attrib *attr = NULL;
int tac_fd, srvr;
if (exclude_users) {
char *user, *list;
list = strdup(exclude_users);
if (list) {
static const char *delim = ", \t\n";
bool islocal = 0;
user = strtok(list, delim);
list = NULL;
while (user) {
if(!strcmp(user, pb->name)) {
islocal = 1;
break;
}
user = strtok(NULL, delim);
}
free(list);
if (islocal)
return 2;
}
}
if(!*tac_service) /* reported at config file processing */
return ret;
print_servers();
tac_chk_anyresp();
for(srvr=0; srvr < tac_srv_no && !done; srvr++) {
if (tac_srv[srvr].not_resp)
continue; /* don't retry if previously not responding */
arep.msg = NULL;
arep.attr = NULL;
arep.status = TAC_PLUS_AUTHOR_STATUS_ERROR; /* if author_send fails */
tac_fd = connect_tacacs(&attr, srvr);
if (tac_fd < 0) {
tac_srv[srvr].not_resp = 1;
if(debug)
syslog(LOG_WARNING, "%s: failed to connect TACACS+ server %s,"
" ret=%d: %m", nssname, tac_srv[srvr].addr ?
tac_ntop(tac_srv[srvr].addr->ai_addr) : "unknown", tac_fd);
tac_free_attrib(&attr);
continue;
}
ret = tac_author_send(tac_fd, pb->name, "", tac_rhost, attr);
if(ret < 0) {
if(debug)
syslog(LOG_WARNING, "%s: TACACS+ server %s authorization "
"failed (%d) user (%s)", nssname, tac_srv[srvr].addr ?
tac_ntop(tac_srv[srvr].addr->ai_addr) : "unknown", ret,
pb->name);
}
else {
errno = 0;
ret = tac_author_read(tac_fd, &arep);
if (ret == LIBTAC_STATUS_PROTOCOL_ERR)
syslog(LOG_WARNING, "%s: TACACS+ server %s read failed with"
" protocol error (incorrect shared secret?) user %s",
nssname, tac_ntop(tac_srv[srvr].addr->ai_addr), pb->name);
else if (ret < 0) /* ret == 1 OK transaction, use arep.status */
syslog(LOG_WARNING, "%s: TACACS+ server %s read failed (%d) for"
" user %s: %m", nssname,
tac_ntop(tac_srv[srvr].addr->ai_addr), ret, pb->name);
}
tac_free_attrib(&attr);
close(tac_fd);
if(ret < 0)
continue;
if(arep.status == AUTHOR_STATUS_PASS_ADD ||
arep.status == AUTHOR_STATUS_PASS_REPL) {
ret = got_tacacs_user(arep.attr, pb);
if(debug>1)
syslog(LOG_DEBUG, "%s: TACACS+ server %s successful for user %s"
" local lookup %s", nssname,
tac_ntop(tac_srv[srvr].addr->ai_addr), pb->name,
ret?"copy problem":"OK");
else if(debug)
syslog(LOG_DEBUG, "%s: TACACS+ server %s success on user %s",
nssname, tac_ntop(tac_srv[srvr].addr->ai_addr), pb->name);
done = 1; /* break out of loop after arep cleanup */
}
else {
ret = 1; /* in case last server */
if(debug)
syslog(LOG_DEBUG, "%s: TACACS+ server %s replies user %s"
" invalid (%d)", nssname,
tac_ntop(tac_srv[srvr].addr->ai_addr), pb->name,
arep.status);
}
if(arep.msg)
free(arep.msg);
if(arep.attr) /* free returned attributes */
tac_free_attrib(&arep.attr);
}
return ret < 0? 1 : ret;
}
static int
lookup_mapped_uid(struct pwbuf *pb, uid_t uid, uid_t auid, int session)
{
char *loginname, mappedname[256];
uint16_t flag;
int ret = 1;
mappedname[0] = '\0';
loginname = lookup_mapuid(uid, auid, session,
mappedname, sizeof mappedname, &flag);
if(loginname) {
ret = find_pw_user(loginname, mappedname, pb, flag & MAP_USERHOMEDIR);
free(loginname);
}
return ret;
}
/*
* This is an NSS entry point.
* We implement getpwnam(), because we remap from the tacacs login
* to the local tacacs0 ... tacacs15 users for all other info, and so
* the normal order of "passwd tacplus" (possibly with ldap or anything
* else prior to tacplus) will mean we only get used when there isn't
* a local user to be found.
*
* We try the lookup to the tacacs server first. If we can't make a
* connection to the server for some reason, we also try looking up
* the account name via the mapping file, primarily to handle cases
* where we aren't running with privileges to read the tacacs configuration
* (since it has the secret key).
*/
enum nss_status _nss_tacplus_getpwnam_r(const char *name, struct passwd *pw,
char *buffer, size_t buflen, int *errnop)
{
enum nss_status status = NSS_STATUS_NOTFOUND;
int result, lookup;
struct pwbuf pbuf;
result = get_config(errnop, 1);
if(result)
return status;
/* marshal the args for the lower level functions */
pbuf.name = (char *)name;
pbuf.pw = pw;
pbuf.buf = buffer;
pbuf.buflen = buflen;
pbuf.errnop = errnop;
lookup = lookup_tacacs_user(&pbuf);
if(!lookup) {
status = NSS_STATUS_SUCCESS;
if (errnop)
*errnop = 0;
}
else if(lookup == 1) { /* 2 means exclude_users match */
uint16_t flag;
/*
* If we can't contact a tacacs server (either not configured, or
* more likely, we aren't running as root and the config for the
* server is not readable by our uid for security reasons), see if
* we can find the user via the mapping database, and if so, use
* that. This will work for non-root users as long as the requested
* name is in use (that is, logged in), which will be the most
* common case of wanting to use the original login name by non-root
* users.
*/
char *mapname = lookup_mapname(name, -1, -1, NULL, &flag);
if(mapname != name && !find_pw_user(name, mapname, &pbuf,
flag & MAP_USERHOMEDIR))
status = NSS_STATUS_SUCCESS;
}
if (status == NSS_STATUS_SUCCESS && errnop)
*errnop = 0; /* be sane, no stale errno */
return status;
}
/*
* This is an NSS entry point.
* We implement getpwuid(), for anything that wants to get the original
* login name from the uid.
* If it matches an entry in the map, we use that data to replace
* the data from the local passwd file (not via NSS).
* locally from the map.
*
* This can be made to work 2 different ways, and we need to choose
* one, or make it configurable.
*
* 1) Given a valid auid and a session id, and a mapped user logged in,
* we'll match only that user. That is, we can only do the lookup
* successfully for child processes of the mapped tacacs login, and
* only while still logged in (map entry is valid).
*
* 2) Use auid/session wildcards, and and always match on the first valid
* tacacs map file entry. This means if two tacacs users are logged in
* at the same privilege level at the same time, uid lookups for ps, ls,
* etc. will return the first (in the map file, not necessarily first
* logged in) mapped name.
*
* For now, if auid and session are set, I try them, and if that lookup
* fails, try the wildcard.
*
* Only works while the UID is in use for a mapped user, and only
* for processes invoked from that session. Other callers will
* just get the files, ldap, or nis entry for the UID
* Only works while the UID is in use for a mapped user, and returns
* the first match from the mapped users.
*/
enum nss_status _nss_tacplus_getpwuid_r(uid_t uid, struct passwd *pw,
char *buffer, size_t buflen, int *errnop)
{
struct pwbuf pb;
enum nss_status status = NSS_STATUS_NOTFOUND;
int session;
uid_t auid;
(void) get_config(errnop, 1);
/* config errors aren't fatal here */
if (min_uid != ~0U && uid < min_uid) {
if(debug > 1)
syslog(LOG_DEBUG, "%s: uid %u < min_uid %u, don't lookup",
nssname, uid, min_uid);
return status;
}
auid = audit_getloginuid(); /* audit_setloginuid not called */
session = map_get_sessionid();
/* marshal the args for the lower level functions */
pb.pw = pw;
pb.buf = buffer;
pb.buflen = buflen;
pb.errnop = errnop;
pb.name = NULL;
/*
* the else case will only be called if we don't have an auid or valid
* sessionid, since otherwise the first call will be using wildcards,
* since the getloginuid and get_sessionid calls will "fail".
*/
if(!lookup_mapped_uid(&pb, uid, auid, session))
status = NSS_STATUS_SUCCESS;
else if((auid != (uid_t)-1 || session != ~0U) &&
!lookup_mapped_uid(&pb, uid, (uid_t)-1, ~0))
status = NSS_STATUS_SUCCESS;
return status;
}
static void get_remote_addr(void)
{
struct sockaddr_storage addr;
socklen_t len = sizeof addr;
char ipstr[INET6_ADDRSTRLEN];
/* This is so we can fill in the rhost field when we talk to the
* TACACS+ server, when it's an ssh connection, so sites that refuse
* authorization unless from specific IP addresses will get that
* information. It's pretty much of a hack, but it works.
*/
if (getpeername(0, (struct sockaddr*)&addr, &len) == -1)
return;
*ipstr = 0;
if (addr.ss_family == AF_INET) {
struct sockaddr_in *s = (struct sockaddr_in *)&addr;
inet_ntop(AF_INET, &s->sin_addr, ipstr, sizeof ipstr);
} else {
struct sockaddr_in6 *s = (struct sockaddr_in6 *)&addr;
inet_ntop(AF_INET6, &s->sin6_addr, ipstr, sizeof ipstr);
}
snprintf(tac_rhost, sizeof tac_rhost, "%s", ipstr);
if(debug > 1 && tac_rhost[0])
syslog(LOG_DEBUG, "%s: rhost=%s", nssname, tac_rhost);
}
/* start of infrastructure for getgr* routines */
static int copyuser(char **grmem, const char *user, long long *blen,
int *err)
{
size_t l = strlen(user) + 1;
*blen -= l;
if (*blen < 0) {
*err = ERANGE;
return 1;
}
strcpy(*grmem, user);
*grmem += l;
return 0;
}
/*
* Return a char ** list of strings of usernames from the mapping db
* that for each username such as tacacs15, looks up that name and
* replaces it with usernames logged in and mapped to that name,
* for replacing the gr_mem field for getgrent(), etc.
* Passed the original gr_mem array straight from the group file.
* All strings go into buf, and we return ERANGE in *err if there
* isn't enough room.
* The allocated memory will leak, but it's re-used on each call, so
* not too signficant, and if endgrent() gets called, we'll clean up.
*/
static char **
fixup_gr_mem(const char *grnam, const char **gr_in, char *buf,
size_t *lenp, int *err)
{
int nadded = 0, midx = 0;
long long l = 0, len = *lenp; /* size_t unsigned on some systems */
const char **in;
char **out = NULL, *mem = buf;
char **gr_mem;
const unsigned align = sizeof(void *) - 1;