1/* Copyright (C) 2004-2021 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Ulrich Drepper <drepper@redhat.com>, 2004.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#include <assert.h>
20#include <errno.h>
21#include <grp.h>
22#include <stdlib.h>
23#include <string.h>
24#include <unistd.h>
25#include <not-cancel.h>
26
27#include "nscd-client.h"
28#include "nscd_proto.h"
29
30
31/* We use the same mapping as in nscd_getgr. */
32libc_locked_map_ptr (extern, __gr_map_handle) attribute_hidden;
33
34
35int
36__nscd_getgrouplist (const char *user, gid_t group, long int *size,
37 gid_t **groupsp, long int limit)
38{
39 size_t userlen = strlen (user) + 1;
40 int gc_cycle;
41 int nretries = 0;
42
43 /* If the mapping is available, try to search there instead of
44 communicating with the nscd. */
45 struct mapped_database *mapped;
46 mapped = __nscd_get_map_ref (GETFDGR, "group", &__gr_map_handle, &gc_cycle);
47
48 retry:;
49 char *respdata = NULL;
50 int retval = -1;
51 int sock = -1;
52 initgr_response_header initgr_resp;
53
54 if (mapped != NO_MAPPING)
55 {
56 struct datahead *found = __nscd_cache_search (INITGROUPS, user,
57 userlen, mapped,
58 sizeof initgr_resp);
59 if (found != NULL)
60 {
61 respdata = (char *) (&found->data[0].initgrdata + 1);
62 initgr_resp = found->data[0].initgrdata;
63 char *recend = (char *) found->data + found->recsize;
64
65 /* Now check if we can trust initgr_resp fields. If GC is
66 in progress, it can contain anything. */
67 if (mapped->head->gc_cycle != gc_cycle)
68 {
69 retval = -2;
70 goto out;
71 }
72
73 if (respdata + initgr_resp.ngrps * sizeof (int32_t) > recend)
74 goto out;
75 }
76 }
77
78 /* If we do not have the cache mapped, try to get the data over the
79 socket. */
80 if (respdata == NULL)
81 {
82 sock = __nscd_open_socket (user, userlen, INITGROUPS, &initgr_resp,
83 sizeof (initgr_resp));
84 if (sock == -1)
85 {
86 /* nscd not running or wrong version. */
87 __nss_not_use_nscd_group = 1;
88 goto out;
89 }
90 }
91
92 if (initgr_resp.found == 1)
93 {
94 /* The following code assumes that gid_t and int32_t are the
95 same size. This is the case for al existing implementation.
96 If this should change some code needs to be added which
97 doesn't use memcpy but instead copies each array element one
98 by one. */
99 assert (sizeof (int32_t) == sizeof (gid_t));
100 assert (initgr_resp.ngrps >= 0);
101
102 /* Make sure we have enough room. We always count GROUP in even
103 though we might not end up adding it. */
104 if (*size < initgr_resp.ngrps + 1)
105 {
106 gid_t *newp = realloc (*groupsp,
107 (initgr_resp.ngrps + 1) * sizeof (gid_t));
108 if (newp == NULL)
109 /* We cannot increase the buffer size. */
110 goto out_close;
111
112 *groupsp = newp;
113 *size = initgr_resp.ngrps + 1;
114 }
115
116 if (respdata == NULL)
117 {
118 /* Read the data from the socket. */
119 if ((size_t) __readall (sock, *groupsp, initgr_resp.ngrps
120 * sizeof (gid_t))
121 == initgr_resp.ngrps * sizeof (gid_t))
122 retval = initgr_resp.ngrps;
123 }
124 else
125 {
126 /* Just copy the data. */
127 retval = initgr_resp.ngrps;
128 memcpy (*groupsp, respdata, retval * sizeof (gid_t));
129 }
130 }
131 else
132 {
133 if (__glibc_unlikely (initgr_resp.found == -1))
134 {
135 /* The daemon does not cache this database. */
136 __nss_not_use_nscd_group = 1;
137 goto out_close;
138 }
139
140 /* No group found yet. */
141 retval = 0;
142
143 assert (*size >= 1);
144 }
145
146 /* Check whether GROUP is part of the mix. If not, add it. */
147 if (retval >= 0)
148 {
149 int cnt;
150 for (cnt = 0; cnt < retval; ++cnt)
151 if ((*groupsp)[cnt] == group)
152 break;
153
154 if (cnt == retval)
155 (*groupsp)[retval++] = group;
156 }
157
158 out_close:
159 if (sock != -1)
160 __close_nocancel_nostatus (sock);
161 out:
162 if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0)
163 {
164 /* When we come here this means there has been a GC cycle while we
165 were looking for the data. This means the data might have been
166 inconsistent. Retry if possible. */
167 if ((gc_cycle & 1) != 0 || ++nretries == 5 || retval == -1)
168 {
169 /* nscd is just running gc now. Disable using the mapping. */
170 if (atomic_decrement_val (&mapped->counter) == 0)
171 __nscd_unmap (mapped);
172 mapped = NO_MAPPING;
173 }
174
175 if (retval != -1)
176 goto retry;
177 }
178
179 return retval;
180}
181