1/* Copyright (C) 1989, 1991-2019 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <http://www.gnu.org/licenses/>. */
17
18#include <assert.h>
19#include <errno.h>
20#include <grp.h>
21#include <limits.h>
22#include <stdlib.h>
23#include <string.h>
24#include <unistd.h>
25#include <sys/param.h>
26#include <sys/types.h>
27#include <nsswitch.h>
28#include <scratch_buffer.h>
29#include <config.h>
30
31#include "../nscd/nscd-client.h"
32#include "../nscd/nscd_proto.h"
33
34#ifdef LINK_OBSOLETE_NSL
35# define DEFAULT_CONFIG "compat [NOTFOUND=return] files"
36#else
37# define DEFAULT_CONFIG "files"
38#endif
39
40/* Type of the lookup function. */
41typedef enum nss_status (*initgroups_dyn_function) (const char *, gid_t,
42 long int *, long int *,
43 gid_t **, long int, int *);
44
45static bool use_initgroups_entry;
46
47
48#include "compat-initgroups.c"
49
50
51static int
52internal_getgrouplist (const char *user, gid_t group, long int *size,
53 gid_t **groupsp, long int limit)
54{
55#ifdef USE_NSCD
56 if (__nss_not_use_nscd_group > 0
57 && ++__nss_not_use_nscd_group > NSS_NSCD_RETRY)
58 __nss_not_use_nscd_group = 0;
59 if (!__nss_not_use_nscd_group
60 && !__nss_database_custom[NSS_DBSIDX_group])
61 {
62 int n = __nscd_getgrouplist (user, group, size, groupsp, limit);
63 if (n >= 0)
64 return n;
65
66 /* nscd is not usable. */
67 __nss_not_use_nscd_group = 1;
68 }
69#endif
70
71 enum nss_status status = NSS_STATUS_UNAVAIL;
72 int no_more = 0;
73
74 /* Never store more than the starting *SIZE number of elements. */
75 assert (*size > 0);
76 (*groupsp)[0] = group;
77 /* Start is one, because we have the first group as parameter. */
78 long int start = 1;
79
80 if (__nss_initgroups_database == NULL)
81 {
82 if (__nss_database_lookup ("initgroups", NULL, "",
83 &__nss_initgroups_database) < 0)
84 {
85 if (__nss_group_database == NULL)
86 no_more = __nss_database_lookup ("group", NULL, DEFAULT_CONFIG,
87 &__nss_group_database);
88
89 __nss_initgroups_database = __nss_group_database;
90 }
91 else
92 use_initgroups_entry = true;
93 }
94 else
95 /* __nss_initgroups_database might have been set through
96 __nss_configure_lookup in which case use_initgroups_entry was
97 not set here. */
98 use_initgroups_entry = __nss_initgroups_database != __nss_group_database;
99
100 service_user *nip = __nss_initgroups_database;
101 while (! no_more)
102 {
103 long int prev_start = start;
104
105 initgroups_dyn_function fct = __nss_lookup_function (nip,
106 "initgroups_dyn");
107 if (fct == NULL)
108 status = compat_call (nip, user, group, &start, size, groupsp,
109 limit, &errno);
110 else
111 status = DL_CALL_FCT (fct, (user, group, &start, size, groupsp,
112 limit, &errno));
113
114 /* Remove duplicates. */
115 long int cnt = prev_start;
116 while (cnt < start)
117 {
118 long int inner;
119 for (inner = 0; inner < prev_start; ++inner)
120 if ((*groupsp)[inner] == (*groupsp)[cnt])
121 break;
122
123 if (inner < prev_start)
124 (*groupsp)[cnt] = (*groupsp)[--start];
125 else
126 ++cnt;
127 }
128
129 /* This is really only for debugging. */
130 if (NSS_STATUS_TRYAGAIN > status || status > NSS_STATUS_RETURN)
131 __libc_fatal ("Illegal status in internal_getgrouplist.\n");
132
133 /* For compatibility reason we will continue to look for more
134 entries using the next service even though data has already
135 been found if the nsswitch.conf file contained only a 'groups'
136 line and no 'initgroups' line. If the latter is available
137 we always respect the status. This means that the default
138 for successful lookups is to return. */
139 if ((use_initgroups_entry || status != NSS_STATUS_SUCCESS)
140 && nss_next_action (nip, status) == NSS_ACTION_RETURN)
141 break;
142
143 if (nip->next == NULL)
144 no_more = -1;
145 else
146 nip = nip->next;
147 }
148
149 return start;
150}
151
152/* Store at most *NGROUPS members of the group set for USER into
153 *GROUPS. Also include GROUP. The actual number of groups found is
154 returned in *NGROUPS. Return -1 if the if *NGROUPS is too small. */
155int
156getgrouplist (const char *user, gid_t group, gid_t *groups, int *ngroups)
157{
158 long int size = MAX (1, *ngroups);
159
160 gid_t *newgroups = (gid_t *) malloc (size * sizeof (gid_t));
161 if (__glibc_unlikely (newgroups == NULL))
162 /* No more memory. */
163 // XXX This is wrong. The user provided memory, we have to use
164 // XXX it. The internal functions must be called with the user
165 // XXX provided buffer and not try to increase the size if it is
166 // XXX too small. For initgroups a flag could say: increase size.
167 return -1;
168
169 int total = internal_getgrouplist (user, group, &size, &newgroups, -1);
170
171 memcpy (groups, newgroups, MIN (*ngroups, total) * sizeof (gid_t));
172
173 free (newgroups);
174
175 int retval = total > *ngroups ? -1 : total;
176 *ngroups = total;
177
178 return retval;
179}
180
181nss_interface_function (getgrouplist)
182
183/* Initialize the group set for the current user
184 by reading the group database and using all groups
185 of which USER is a member. Also include GROUP. */
186int
187initgroups (const char *user, gid_t group)
188{
189#if defined NGROUPS_MAX && NGROUPS_MAX == 0
190
191 /* No extra groups allowed. */
192 return 0;
193
194#else
195
196 long int size;
197 gid_t *groups;
198 int ngroups;
199 int result;
200
201 /* We always use sysconf even if NGROUPS_MAX is defined. That way, the
202 limit can be raised in the kernel configuration without having to
203 recompile libc. */
204 long int limit = __sysconf (_SC_NGROUPS_MAX);
205
206 if (limit > 0)
207 /* We limit the size of the intially allocated array. */
208 size = MIN (limit, 64);
209 else
210 /* No fixed limit on groups. Pick a starting buffer size. */
211 size = 16;
212
213 groups = (gid_t *) malloc (size * sizeof (gid_t));
214 if (__glibc_unlikely (groups == NULL))
215 /* No more memory. */
216 return -1;
217
218 ngroups = internal_getgrouplist (user, group, &size, &groups, limit);
219
220 /* Try to set the maximum number of groups the kernel can handle. */
221 do
222 result = setgroups (ngroups, groups);
223 while (result == -1 && errno == EINVAL && --ngroups > 0);
224
225 free (groups);
226
227 return result;
228#endif
229}
230
231nss_interface_function (initgroups)
232