lib/roken/iruserok.c

/*
 * Copyright (c) 1983, 1993, 1994
 *	The Regents of the University of California.  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.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
RCSID("$Id: iruserok.c 17879 2006-08-08 21:50:40Z lha $");
#endif

#include <stdio.h>
#include <ctype.h>
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#ifdef HAVE_NETINET_IN6_H
#include <netinet/in6.h>
#endif
#ifdef HAVE_NETINET6_IN6_H
#include <netinet6/in6.h>
#endif
#ifdef HAVE_RPCSVC_YPCLNT_H
#include <rpcsvc/ypclnt.h>
#endif

#include "roken.h"

int     __check_rhosts_file = 1;
char    *__rcmd_errstr = 0;

/*
 * Returns "true" if match, 0 if no match.
 */
static
int
__icheckhost(unsigned raddr, const char *lhost)
{
	struct hostent *hp;
	u_long laddr;
	char **pp;

	/* Try for raw ip address first. */
	if (isdigit((unsigned char)*lhost)
	    && (long)(laddr = inet_addr(lhost)) != -1)
		return (raddr == laddr);

	/* Better be a hostname. */
	if ((hp = gethostbyname(lhost)) == NULL)
		return (0);

	/* Spin through ip addresses. */
	for (pp = hp->h_addr_list; *pp; ++pp)
	        if (memcmp(&raddr, *pp, sizeof(u_long)) == 0)
			return (1);

	/* No match. */
	return (0);
}

/*
 * Returns 0 if ok, -1 if not ok.
 */
static
int
__ivaliduser(FILE *hostf, unsigned raddr, const char *luser,
	     const char *ruser)
{
	char *user, *p;
	int ch;
	char buf[MaxHostNameLen + 128];		/* host + login */
	char hname[MaxHostNameLen];
	struct hostent *hp;
	/* Presumed guilty until proven innocent. */
	int userok = 0, hostok = 0;
#ifdef HAVE_YP_GET_DEFAULT_DOMAIN
	char *ypdomain;

	if (yp_get_default_domain(&ypdomain))
		ypdomain = NULL;
#else
#define	ypdomain NULL
#endif
	/* We need to get the damn hostname back for netgroup matching. */
	if ((hp = gethostbyaddr((char *)&raddr,
				sizeof(u_long),
				AF_INET)) == NULL)
		return (-1);
	strlcpy(hname, hp->h_name, sizeof(hname));

	while (fgets(buf, sizeof(buf), hostf)) {
		p = buf;
		/* Skip lines that are too long. */
		if (strchr(p, '\n') == NULL) {
			while ((ch = getc(hostf)) != '\n' && ch != EOF);
			continue;
		}
		if (*p == '\n' || *p == '#') {
			/* comment... */
			continue;
		}
		while (*p != '\n' && *p != ' ' && *p != '\t' && *p != '\0') {
		        if (isupper((unsigned char)*p))
			    *p = tolower((unsigned char)*p);
			p++;
		}
		if (*p == ' ' || *p == '\t') {
			*p++ = '\0';
			while (*p == ' ' || *p == '\t')
				p++;
			user = p;
			while (*p != '\n' && *p != ' ' &&
			    *p != '\t' && *p != '\0')
				p++;
		} else
			user = p;
		*p = '\0';
		/*
		 * Do +/- and +@/-@ checking. This looks really nasty,
		 * but it matches SunOS's behavior so far as I can tell.
		 */
		switch(buf[0]) {
		case '+':
			if (!buf[1]) {     /* '+' matches all hosts */
				hostok = 1;
				break;
			}
			if (buf[1] == '@')  /* match a host by netgroup */
				hostok = innetgr((char *)&buf[2],
					(char *)&hname, NULL, ypdomain);
			else		/* match a host by addr */
				hostok = __icheckhost(raddr,(char *)&buf[1]);
			break;
		case '-':     /* reject '-' hosts and all their users */
			if (buf[1] == '@') {
				if (innetgr((char *)&buf[2],
					      (char *)&hname, NULL, ypdomain))
					return(-1);
			} else {
				if (__icheckhost(raddr,(char *)&buf[1]))
					return(-1);
			}
			break;
		default:  /* if no '+' or '-', do a simple match */
			hostok = __icheckhost(raddr, buf);
			break;
		}
		switch(*user) {
		case '+':
			if (!*(user+1)) {      /* '+' matches all users */
				userok = 1;
				break;
			}
			if (*(user+1) == '@')  /* match a user by netgroup */
				userok = innetgr(user+2, NULL, (char *)ruser,
						 ypdomain);
			else	   /* match a user by direct specification */
				userok = !(strcmp(ruser, user+1));
			break;
		case '-': 		/* if we matched a hostname, */
			if (hostok) {   /* check for user field rejections */
				if (!*(user+1))
					return(-1);
				if (*(user+1) == '@') {
					if (innetgr(user+2, NULL,
						    (char *)ruser, ypdomain))
						return(-1);
				} else {
					if (!strcmp(ruser, user+1))
						return(-1);
				}
			}
			break;
		default:	/* no rejections: try to match the user */
			if (hostok)
				userok = !(strcmp(ruser,*user ? user : luser));
			break;
		}
		if (hostok && userok)
			return(0);
	}
	return (-1);
}

/*
 * New .rhosts strategy: We are passed an ip address. We spin through
 * hosts.equiv and .rhosts looking for a match. When the .rhosts only
 * has ip addresses, we don't have to trust a nameserver.  When it
 * contains hostnames, we spin through the list of addresses the nameserver
 * gives us and look for a match.
 *
 * Returns 0 if ok, -1 if not ok.
 */
int ROKEN_LIB_FUNCTION
iruserok(unsigned raddr, int superuser, const char *ruser, const char *luser)
{
	char *cp;
	struct stat sbuf;
	struct passwd *pwd;
	FILE *hostf;
	uid_t uid;
	int first;
	char pbuf[MaxPathLen];

	first = 1;
	hostf = superuser ? NULL : fopen(_PATH_HEQUIV, "r");
again:
	if (hostf) {
		if (__ivaliduser(hostf, raddr, luser, ruser) == 0) {
			fclose(hostf);
			return (0);
		}
		fclose(hostf);
	}
	if (first == 1 && (__check_rhosts_file || superuser)) {
		first = 0;
		if ((pwd = k_getpwnam((char*)luser)) == NULL)
			return (-1);
		snprintf (pbuf, sizeof(pbuf), "%s/.rhosts", pwd->pw_dir);

		/*
		 * Change effective uid while opening .rhosts.  If root and
		 * reading an NFS mounted file system, can't read files that
		 * are protected read/write owner only.
		 */
		uid = geteuid();
		if (seteuid(pwd->pw_uid) < 0)
			return (-1);
		hostf = fopen(pbuf, "r");
		seteuid(uid);

		if (hostf == NULL)
			return (-1);
		/*
		 * If not a regular file, or is owned by someone other than
		 * user or root or if writeable by anyone but the owner, quit.
		 */
		cp = NULL;
		if (lstat(pbuf, &sbuf) < 0)
			cp = ".rhosts lstat failed";
		else if (!S_ISREG(sbuf.st_mode))
			cp = ".rhosts not regular file";
		else if (fstat(fileno(hostf), &sbuf) < 0)
			cp = ".rhosts fstat failed";
		else if (sbuf.st_uid && sbuf.st_uid != pwd->pw_uid)
			cp = "bad .rhosts owner";
		else if (sbuf.st_mode & (S_IWGRP|S_IWOTH))
			cp = ".rhosts writeable by other than owner";
		/* If there were any problems, quit. */
		if (cp) {
			__rcmd_errstr = cp;
			fclose(hostf);
			return (-1);
		}
		goto again;
	}
	return (-1);
}