1/*	$OpenBSD: getgrouplist.c,v 1.30 2022/08/02 17:00:15 deraadt Exp $ */
2/*
3 * Copyright (c) 2008 Ingo Schwarze <schwarze@usta.de>
4 * Copyright (c) 1991, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32/*
33 * get credential
34 */
35#include <sys/types.h>
36#include <sys/limits.h>
37#include <string.h>
38#include <unistd.h>
39#include <stdio.h>
40#include <stdlib.h>
41#include <grp.h>
42#include <pwd.h>
43#include <errno.h>
44
45#include <rpc/rpc.h>
46#include <rpcsvc/yp.h>
47#include <rpcsvc/ypclnt.h>
48
49#ifdef YP
50#define _PATH_NETID	"/etc/netid"
51#define MAXLINELENGTH	1024
52
53static int _parse_netid(char*, uid_t, gid_t*, int*, int);
54static int _read_netid(const char *, uid_t, gid_t*, int*, int);
55
56/*
57 * Parse one string of the form "uid:gid[,gid[,...]]".
58 * If the uid matches, add the groups to the group list.
59 * If the groups fit, return 1, otherwise return -1.
60 * If the uid does not match, return 0.
61 */
62static int
63_parse_netid(char *netid, uid_t uid, gid_t *groups, int *ngroups,
64	     int maxgroups)
65{
66	const char *errstr = NULL;
67	char *start, *p;
68	uid_t tuid;
69	gid_t gid;
70	int i;
71
72	/* Check the uid. */
73	p = strchr(netid, ':');
74	if (!p)
75		return (0);
76	*p++ = '\0';
77	tuid = (uid_t)strtonum(netid, 0, UID_MAX, &errstr);
78	if (errstr || tuid != uid)
79		return (0);
80
81        /* Loop over the gids. */
82	while (p && *p) {
83		start = p;
84		p = strchr(start, ',');
85		if (p)
86			*p++ = '\0';
87		gid = (gid_t)strtonum(start, 0, GID_MAX, &errstr);
88		if (errstr)
89			continue;
90
91		/* Skip this group if it is already in the list. */
92		for (i = 0; i < *ngroups; i++)
93			if (groups[i] == gid)
94				break;
95
96		/* Try to add this new group to the list. */
97		if (i == *ngroups) {
98			if (*ngroups >= maxgroups)
99				return (-1);
100			groups[(*ngroups)++] = gid;
101		}
102	}
103	return (1);
104}
105
106/*
107 * Search /etc/netid for a particular uid and process that line.
108 * See _parse_netid for details, including return values.
109 */
110static int
111_read_netid(const char *key, uid_t uid, gid_t *groups, int *ngroups,
112	    int maxgroups)
113{
114	FILE *fp;
115	char line[MAXLINELENGTH], *p;
116	int found = 0;
117
118	fp = fopen(_PATH_NETID, "re");
119	if (!fp)
120		return (0);
121	while (!found && fgets(line, sizeof(line), fp)) {
122		p = strchr(line, '\n');
123		if (p)
124			*p = '\0';
125		else { /* Skip lines that are too long. */
126			int ch;
127			while ((ch = getc_unlocked(fp)) != '\n' && ch != EOF)
128				;
129			continue;
130		}
131		p = strchr(line, ' ');
132		if (!p)
133			continue;
134		*p++ = '\0';
135		if (strcmp(line, key))
136			continue;
137		found = _parse_netid(p, uid, groups, ngroups, maxgroups);
138	}
139	(void)fclose(fp);
140	return (found);
141}
142#endif /* YP */
143
144int
145getgrouplist(const char *uname, gid_t agroup, gid_t *groups, int *grpcnt)
146{
147	int i, ngroups = 0, ret = 0, maxgroups = *grpcnt, bail;
148	int needyp = 0, foundyp = 0;
149	int *skipyp = &foundyp;
150	extern struct group *_getgrent_yp(int *);
151	struct group *grp;
152
153	/*
154	 * install primary group
155	 */
156	if (ngroups >= maxgroups) {
157		*grpcnt = ngroups;
158		return (-1);
159	}
160	groups[ngroups++] = agroup;
161
162	/*
163	 * Scan the group file to find additional groups.
164	 */
165	setgrent();
166	while ((grp = _getgrent_yp(skipyp)) || foundyp) {
167		if (foundyp) {
168			if (foundyp > 0)
169				needyp = 1;
170			else
171				skipyp = NULL;
172			foundyp = 0;
173			continue;
174		}
175		if (grp->gr_gid == agroup)
176			continue;
177		for (bail = 0, i = 0; bail == 0 && i < ngroups; i++)
178			if (groups[i] == grp->gr_gid)
179				bail = 1;
180		if (bail)
181			continue;
182		for (i = 0; grp->gr_mem[i]; i++) {
183			if (!strcmp(grp->gr_mem[i], uname)) {
184				if (ngroups >= maxgroups) {
185					ret = -1;
186					goto out;
187				}
188				groups[ngroups++] = grp->gr_gid;
189				break;
190			}
191		}
192	}
193
194#ifdef YP
195	/*
196	 * If we were told that there is a YP marker, look at netid data.
197	 */
198	if (skipyp && needyp) {
199		char buf[MAXLINELENGTH], *ypdata = NULL, *key;
200		static char *__ypdomain;
201		struct passwd pwstore;
202		int ypdatalen;
203
204		/* Construct the netid key to look up. */
205		if (getpwnam_r(uname, &pwstore, buf, sizeof buf, NULL) ||
206		    (!__ypdomain && yp_get_default_domain(&__ypdomain)))
207			goto out;
208		i = asprintf(&key, "unix.%u@%s", pwstore.pw_uid, __ypdomain);
209		if (i == -1)
210			goto out;
211
212		/* First scan the static netid file. */
213		switch (_read_netid(key, pwstore.pw_uid,
214		    groups, &ngroups, maxgroups)) {
215		case -1:
216			ret = -1;
217			/* FALLTHROUGH */
218		case 1:
219			free(key);
220			goto out;
221		default:
222			break;
223		}
224
225		/* Only access YP when there is no static entry. */
226		if (!yp_match(__ypdomain, "netid.byname", key,
227		    (int)strlen(key), &ypdata, &ypdatalen))
228			if (_parse_netid(ypdata, pwstore.pw_uid,
229			    groups, &ngroups, maxgroups) == -1)
230				ret = -1;
231
232		free(key);
233		free(ypdata);
234	}
235#endif /* YP */
236
237out:
238	endgrent();
239	*grpcnt = ngroups;
240	return (ret);
241}
242DEF_WEAK(getgrouplist);
243