1 /*----------------------------------------------------------------------
2 * Modified for Linux-PAM by Al Longyear <longyear@netcom.com> 96/5/5
3 * Modifications, Cristian Gafton 97/2/8
4 * Modifications, Peter Allgeyer 97/3
5 * Modifications (netgroups and fixes), Nicolai Langfeldt 97/3/21
6 * Security fix: 97/10/2 - gethostbyname called repeatedly without care
7 * Modification (added privategroup option) Andrew <morgan@transmeta.com>
8 *----------------------------------------------------------------------
9 * Copyright (c) 1983, 1993, 1994
10 * The Regents of the University of California. All rights reserved.
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. All advertising materials mentioning features or use of this software
21 * must display the following acknowledgement:
22 * This product includes software developed by the University of
23 * California, Berkeley and its contributors.
24 * 4. Neither the name of the University nor the names of its contributors
25 * may be used to endorse or promote products derived from this software
26 * without specific prior written permission.
28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
41 #include <security/_pam_aconf.h>
43 #define USER_RHOSTS_FILE "/.rhosts" /* prefixed by user's home dir */
49 #ifdef HAVE_SYS_FSUID_H
50 #include <sys/fsuid.h>
51 #endif /* HAVE_SYS_FSUID_H */
53 #include <sys/types.h>
58 #include <sys/param.h>
59 #include <sys/socket.h>
60 #include <netinet/in.h>
61 #include <netdb.h> /* This is supposed(?) to contain the following */
62 int innetgr(const char *, const char *, const char *,const char *);
67 #include <arpa/inet.h>
78 # include <linux/sockios.h>
81 # include <sys/fsuid.h>
82 # endif /* __USE_MISC */
88 #include <sys/signal.h>
92 #define _PATH_HEQUIV "/etc/hosts.equiv"
93 #endif /* _PATH_HEQUIV */
95 #define PAM_SM_AUTH /* only defines this management group */
97 #include <security/pam_modules.h>
98 #include <security/_pam_macros.h>
99 #include <security/_pam_modutil.h>
101 /* to the best of my knowledge, all modern UNIX boxes have 32 bit integers */
102 #define U32 unsigned int
106 * Options for this module
110 int opt_no_hosts_equiv;
111 int opt_hosts_equiv_rootok;
115 int opt_disallow_null_authtok;
119 int opt_private_group;
120 int opt_no_uid_check;
121 const char *superuser;
122 const char *last_error;
126 static void _pam_log(int err, const char *format, ...)
130 va_start(args, format);
131 openlog("pam_rhosts_auth", LOG_CONS|LOG_PID, LOG_AUTH);
132 vsyslog(err, format, args);
137 static void set_option (struct _options *opts, const char *arg)
139 if (strcmp(arg, "no_hosts_equiv") == 0) {
140 opts->opt_no_hosts_equiv = 1;
144 if (strcmp(arg, "hosts_equiv_rootok") == 0) {
145 opts->opt_hosts_equiv_rootok = 1;
149 if (strcmp(arg, "no_rhosts") == 0) {
150 opts->opt_no_rhosts = 1;
154 if (strcmp(arg, "debug") == 0) {
155 D(("debugging enabled"));
160 if (strcmp(arg, "no_warn") == 0) {
161 opts->opt_nowarn = 1;
165 if (strcmp(arg, "promiscuous") == 0) {
166 opts->opt_promiscuous = 1; /* used to permit '+' in ...hosts file */
170 if (strcmp(arg, "suppress") == 0) {
171 opts->opt_suppress = 1; /* used to suppress failure warning message */
175 if (strcmp(arg, "privategroup") == 0) {
176 opts->opt_private_group = 1; /* used to permit group write on .rhosts
177 file if group has same name as owner */
181 if (strcmp(arg, "no_uid_check") == 0) {
182 opts->opt_no_uid_check = 1; /* NIS optimization */
186 if (strcmp(arg, "superuser=") == 0) {
187 opts->superuser = arg+sizeof("superuser=")-1;
191 * All other options are ignored at the present time.
193 _pam_log(LOG_WARNING, "unrecognized option '%s'", arg);
196 static void set_parameters (struct _options *opts, int flags,
197 int argc, const char **argv)
199 opts->opt_silent = flags & PAM_SILENT;
200 opts->opt_disallow_null_authtok = flags & PAM_DISALLOW_NULL_AUTHTOK;
203 set_option (opts, *argv);
209 * Obtain the name of the remote host. Currently, this is simply by
210 * requesting the contents of the PAM_RHOST item.
213 static int pam_get_rhost(pam_handle_t *pamh, const char **rhost
214 , const char *prompt)
219 retval = pam_get_item (pamh, PAM_RHOST, (const void **)¤t);
220 if (retval != PAM_SUCCESS)
223 if (current == NULL) {
228 return retval; /* pass on any error from conversation */
232 * Obtain the name of the remote user. Currently, this is simply by
233 * requesting the contents of the PAM_RUSER item.
236 static int pam_get_ruser(pam_handle_t *pamh, const char **ruser,
242 retval = pam_get_item (pamh, PAM_RUSER, (const void **)¤t);
243 if (retval != PAM_SUCCESS) {
247 if (current == NULL) {
252 return retval; /* pass on any error from conversation */
256 * Returns 1 if positive match, 0 if no match, -1 if negative match.
260 __icheckhost (pam_handle_t *pamh, struct _options *opts, U32 raddr
261 , register char *lhost, const char *rhost)
265 int negate=1; /* Multiply return with this to get -1 instead of 1 */
268 /* Check nis netgroup. We assume that pam has done all needed
269 paranoia checking before we are handed the rhost */
270 if (strncmp("+@",lhost,2) == 0)
271 return(innetgr(&lhost[2],rhost,NULL,NULL));
273 if (strncmp("-@",lhost,2) == 0)
274 return(-innetgr(&lhost[2],rhost,NULL,NULL));
277 if (strncmp("-",lhost,1) == 0) {
280 } else if (strcmp("+",lhost) == 0) {
281 (void) pam_get_item(pamh, PAM_USER, (const void **)&user);
282 D(("user %s has a `+' host entry", user));
283 if (opts->opt_promiscuous)
284 return (1); /* asking for trouble, but ok.. */
285 /* If not promiscuous: handle as negative */
287 } else if (strncmp("+",lhost,1) == 0) {
288 /* '+hostname' is supposed to be equivalent to 'hostname' */
293 /* Try for raw ip address first. */
294 if (isdigit(*lhost) && (long)(laddr = inet_addr(lhost)) != -1)
295 return (negate*(! (raddr ^ laddr)));
297 /* Better be a hostname. */
298 hp = gethostbyname(lhost);
302 /* Spin through ip addresses. */
303 for (pp = hp->h_addr_list; *pp; ++pp)
304 if (!memcmp (&raddr, *pp, sizeof (U32)))
311 /* Returns 1 on positive match, 0 on no match, -1 on negative match */
313 static int __icheckuser(pam_handle_t *pamh, struct _options *opts
314 , const char *luser, const char *ruser
318 luser is user entry from .rhosts/hosts.equiv file
319 ruser is user id on remote host
320 rhost is the remote host name
325 if (strncmp("+@",luser,2) == 0)
326 return (innetgr(&luser[2],NULL,ruser,NULL));
328 if (strncmp("-@",luser,2) == 0)
329 return (-innetgr(&luser[2],NULL,ruser,NULL));
332 if (strncmp("-",luser,1) == 0)
333 return(-(strcmp(&luser[1],ruser) == 0));
336 if (strcmp("+",luser) == 0) {
337 (void) pam_get_item(pamh, PAM_USER, (const void **)&user);
338 _pam_log(LOG_WARNING, "user %s has a `+' user entry", user);
339 if (opts->opt_promiscuous)
341 /* If not promiscuous we handle it as a negative match */
345 /* simple string match */
346 return (strcmp(ruser, luser) == 0);
350 * Returns 1 for blank lines (or only comment lines) and 0 otherwise
353 static int __isempty(char *p)
355 while (*p && isspace(*p)) {
359 return (*p == '\0' || *p == '#') ? 1:0 ;
363 * Returns 0 if positive match, 1 if _not_ ok.
367 __ivaliduser (pam_handle_t *pamh, struct _options *opts,
368 FILE *hostf, U32 raddr,
369 const char *luser, const char *ruser, const char *rhost)
371 register const char *user;
374 char buf[MAXHOSTNAMELEN + 128]; /* host + login */
376 buf[sizeof (buf)-1] = '\0'; /* terminate line */
378 while (fgets(buf, sizeof(buf), hostf) != NULL) { /* hostf file line */
379 p = buf; /* from beginning of file.. */
381 /* Skip empty or comment lines */
386 /* Skip lines that are too long. */
387 if (strchr(p, '\n') == NULL) {
388 int ch = getc(hostf);
390 while (ch != '\n' && ch != EOF)
396 * If there is a hostname at the start of the line. Set it to
397 * lower case. A leading ' ' or '\t' indicates no hostname
400 for (;*p && !isspace(*p); ++p) {
405 * next we want to find the permitted name for the remote user
408 if (*p == ' ' || *p == '\t') {
410 /* <nul> terminate hostname and skip spaces */
411 for (*p++='\0'; *p && isspace(*p); ++p);
413 user = p; /* this is the user's name */
414 while (*p && !isspace(*p))
415 ++p; /* find end of user's name */
419 *p = '\0'; /* <nul> terminate username (+host?) */
421 /* buf -> host(?) ; user -> username(?) */
423 /* First check host part */
424 hcheck=__icheckhost(pamh, opts, raddr, buf, rhost);
430 /* Then check user part */
434 ucheck=__icheckuser(pamh, opts, user, ruser, rhost);
436 /* Positive 'host user' match? */
440 /* Negative 'host -user' match? */
444 /* Neither, go on looking for match */
452 * New .rhosts strategy: We are passed an ip address. We spin through
453 * hosts.equiv and .rhosts looking for a match. When the .rhosts only
454 * has ip addresses, we don't have to trust a nameserver. When it
455 * contains hostnames, we spin through the list of addresses the nameserver
456 * gives us and look for a match.
458 * Returns 0 if ok, -1 if not ok.
462 pam_iruserok(pam_handle_t *pamh,
463 struct _options *opts, U32 raddr, int superuser,
464 const char *ruser, const char *luser, const char *rhost)
472 char pbuf[MAXPATHLEN]; /* potential buffer overrun */
474 if ((!superuser||opts->opt_hosts_equiv_rootok) && !opts->opt_no_hosts_equiv ) {
476 /* try to open system hosts.equiv file */
477 hostf = fopen (_PATH_HEQUIV, "r");
479 answer = __ivaliduser(pamh, opts, hostf, raddr, luser
481 (void) fclose(hostf);
483 return 0; /* remote host is equivalent to localhost */
485 No hosts.equiv file on system.
489 if ( opts->opt_no_rhosts )
493 * Identify user's local .rhosts file
496 pwd = _pammodutil_getpwnam(pamh, luser);
499 * luser is assumed to be valid because of an earlier check for uid = 0
500 * we don't log this error twice. However, this shouldn't happen !
506 /* check for buffer overrun */
507 if (strlen(pwd->pw_dir) + sizeof(USER_RHOSTS_FILE) + 2 >= MAXPATHLEN) {
509 _pam_log(LOG_DEBUG,"home directory for `%s' is too long", luser);
510 return 1; /* to dangerous to try */
513 (void) strcpy(pbuf, pwd->pw_dir);
514 (void) strcat(pbuf, USER_RHOSTS_FILE);
517 * Change effective uid while _reading_ .rhosts. (not just
518 * opening). If root and reading an NFS mounted file system,
519 * can't read files that are 0600 as .rhosts files should be.
522 /* We are root, this will not fail */
524 /* If we are on linux the better way is setfsuid */
525 uid = setfsuid(pwd->pw_uid);
526 hostf = fopen(pbuf, "r");
529 (void) seteuid(pwd->pw_uid);
530 hostf = fopen(pbuf, "r");
535 _pam_log(LOG_DEBUG,"Could not open %s file",pbuf);
541 * If not a regular file, or is owned by someone other than
542 * user or root or if writeable by anyone but the owner, quit.
546 if (lstat(pbuf, &sbuf) < 0 || !S_ISREG(sbuf.st_mode))
547 cp = ".rhosts not regular file";
548 else if (fstat(fileno(hostf), &sbuf) < 0)
549 cp = ".rhosts fstat failed";
550 else if (sbuf.st_uid && sbuf.st_uid != pwd->pw_uid)
551 cp = "bad .rhosts owner";
552 else if (sbuf.st_mode & S_IWOTH)
553 cp = ".rhosts writable by other!";
554 else if (sbuf.st_mode & S_IWGRP) {
556 /* private group caveat */
557 if (opts->opt_private_group) {
558 struct group *grp = getgrgid(sbuf.st_gid);
560 if (NULL == grp || NULL == grp->gr_name
561 || strcmp(luser,grp->gr_name)) {
562 cp = ".rhosts writable by public group";
563 } else if (grp->gr_mem) {
566 /* require at most one member (luser) of this group */
567 for (gcount=0; grp->gr_mem[gcount]; ++gcount) {
568 if (strcmp(grp->gr_mem[gcount], luser)) {
574 cp = ".rhosts writable by other members of group";
578 cp = ".rhosts writable by group";
581 } /* It is _NOT_ safe to append an else here... Do so prior to
584 /* If there were any problems, quit. */
586 opts->last_error = cp;
591 answer = __ivaliduser (pamh, opts, hostf, raddr, luser, ruser, rhost);
595 * Go here to exit after the fsuid/euid has been adjusted so that
596 * they are reset before we exit.
606 (void) fclose(hostf);
612 pam_ruserok (pam_handle_t *pamh,
613 struct _options *opts, const char *rhost, int superuser,
614 const char *ruser, const char *luser)
617 int answer = 1; /* default to failure */
621 opts->last_error = (char *) 0;
622 hp = gethostbyname(rhost); /* identify host */
625 /* First of all check the address length */
626 if (hp->h_length != 4) {
627 _pam_log(LOG_ALERT, "pam_rhosts module can't work with not IPv4 "
629 return 1; /* not allowed */
632 /* loop though address list */
633 for (n = 0; hp->h_addr_list[n]; n++);
634 D(("rhosts: %d addresses", n));
637 addrs = calloc (n, hp->h_length);
638 for (i = 0; i < n; i++)
639 memcpy (addrs+i, hp->h_addr_list[i], hp->h_length);
641 for (i = 0; i < n && answer; i++) {
642 D(("rhosts: address %d is %04x", i, addrs[i]));
643 answer = pam_iruserok(pamh, opts, addrs[i], superuser,
644 ruser, luser, rhost);
645 /* answer == 0 means success */
656 * Internal function to do authentication
659 static int _pam_auth_rhosts (pam_handle_t *pamh,
665 const char *luser = NULL;
666 const char *ruser = NULL, *rhost = NULL;
667 struct _options opts;
671 * Look at the options and set the flags accordingly.
673 memset (&opts, 0, sizeof (opts));
674 set_parameters (&opts, flags, argc, argv);
676 * Obtain the parameters for the various items
678 for (;;) { /* abuse loop to avoid goto */
680 /* get the remotehost */
681 D(("getting rhost"));
682 retval = pam_get_rhost(pamh, &rhost, NULL);
683 (void) pam_set_item(pamh, PAM_RHOST, rhost);
684 if (retval != PAM_SUCCESS) {
685 if (opts.opt_debug) {
686 _pam_log(LOG_DEBUG, "could not get the remote host name");
691 /* get the remote user */
692 D(("getting ruser"));
693 retval = pam_get_ruser(pamh, &ruser, NULL);
694 (void) pam_set_item(pamh, PAM_RUSER, ruser);
695 if (retval != PAM_SUCCESS) {
697 _pam_log(LOG_DEBUG, "could not get the remote username");
701 /* get the local user */
703 retval = pam_get_user(pamh, &luser, NULL);
704 if (retval != PAM_SUCCESS) {
706 _pam_log(LOG_DEBUG, "could not determine name of local user");
710 if (opts.superuser && !strcmp(opts.superuser, luser)) {
714 /* check if the luser uid == 0... --cristiang */
715 if (! opts.opt_no_uid_check) {
716 struct passwd *luser_pwd;
718 luser_pwd = _pammodutil_getpwnam(pamh, luser);
719 if (luser_pwd == NULL) {
721 _pam_log(LOG_DEBUG, "user '%s' unknown to this system",
723 retval = PAM_AUTH_ERR;
726 if (luser_pwd->pw_uid == 0)
728 luser_pwd = NULL; /* forget */
731 * Validate the account information.
733 if (pam_ruserok (pamh, &opts, rhost, as_root, ruser, luser) != 0) {
734 if ( !opts.opt_suppress ) {
735 _pam_log(LOG_WARNING, "denied to %s@%s as %s: %s",
736 ruser, rhost, luser, (opts.last_error==NULL) ?
737 "access not allowed":opts.last_error);
739 retval = PAM_AUTH_ERR;
741 _pam_log(LOG_NOTICE, "allowed to %s@%s as %s",
742 ruser, rhost, luser);
750 /* --- authentication management functions --- */
753 int pam_sm_authenticate (pam_handle_t *pamh,
760 if (sizeof(U32) != 4) {
761 _pam_log (LOG_ALERT, "pam_rhosts module can\'t work on this hardware "
766 retval = _pam_auth_rhosts (pamh, flags, argc, argv);
772 int pam_sm_setcred(pam_handle_t *pamh,int flags,int argc,
778 /* end of module definition */
783 /* static module data */
785 struct pam_module _pam_rhosts_auth_modstruct = {