1 /* Copyright (C) 1998-2023 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 <https://www.gnu.org/licenses/>. */
17
18 #include <assert.h>
19 #include <errno.h>
20 #include <pwd.h>
21 #include <stdint.h>
22 #include <stdio.h>
23 #include <stdlib.h>
24 #include <string.h>
25 #include <unistd.h>
26 #include <sys/mman.h>
27 #include <sys/socket.h>
28 #include <sys/uio.h>
29 #include <sys/un.h>
30 #include <not-cancel.h>
31 #include <_itoa.h>
32
33 #include "nscd-client.h"
34 #include "nscd_proto.h"
35
36 int __nss_not_use_nscd_passwd;
37
38 static int nscd_getpw_r (const char *key, size_t keylen, request_type type,
39 struct passwd *resultbuf, char *buffer,
40 size_t buflen, struct passwd **result);
41
42 int
43 __nscd_getpwnam_r (const char *name, struct passwd *resultbuf, char *buffer,
44 size_t buflen, struct passwd **result)
45 {
46 if (name == NULL)
47 return -1;
48
49 return nscd_getpw_r (name, strlen (name) + 1, GETPWBYNAME, resultbuf,
50 buffer, buflen, result);
51 }
52
53 int
54 __nscd_getpwuid_r (uid_t uid, struct passwd *resultbuf, char *buffer,
55 size_t buflen, struct passwd **result)
56 {
57 char buf[3 * sizeof (uid_t)];
58 buf[sizeof (buf) - 1] = '\0';
59 char *cp = _itoa_word (uid, buf + sizeof (buf) - 1, 10, 0);
60
61 return nscd_getpw_r (cp, buf + sizeof (buf) - cp, GETPWBYUID, resultbuf,
62 buffer, buflen, result);
63 }
64
65
66 libc_locked_map_ptr (static, map_handle);
67 /* Note that we only free the structure if necessary. The memory
68 mapping is not removed since it is not visible to the malloc
69 handling. */
70 void
71 __nscd_pw_map_freemem (void)
72 {
73 if (map_handle.mapped != NO_MAPPING)
74 {
75 void *p = map_handle.mapped;
76 map_handle.mapped = NO_MAPPING;
77 free (p);
78 }
79 }
80
81
82 static int
83 nscd_getpw_r (const char *key, size_t keylen, request_type type,
84 struct passwd *resultbuf, char *buffer, size_t buflen,
85 struct passwd **result)
86 {
87 int gc_cycle;
88 int nretries = 0;
89
90 /* If the mapping is available, try to search there instead of
91 communicating with the nscd. */
92 struct mapped_database *mapped;
93 mapped = __nscd_get_map_ref (GETFDPW, "passwd", &map_handle, &gc_cycle);
94
95 retry:;
96 const char *pw_name = NULL;
97 int retval = -1;
98 const char *recend = (const char *) ~UINTMAX_C (0);
99 pw_response_header pw_resp;
100
101 if (mapped != NO_MAPPING)
102 {
103 struct datahead *found = __nscd_cache_search (type, key, keylen, mapped,
104 sizeof pw_resp);
105 if (found != NULL)
106 {
107 pw_name = (const char *) (&found->data[0].pwdata + 1);
108 pw_resp = found->data[0].pwdata;
109 recend = (const char *) found->data + found->recsize;
110 /* Now check if we can trust pw_resp fields. If GC is
111 in progress, it can contain anything. */
112 if (mapped->head->gc_cycle != gc_cycle)
113 {
114 retval = -2;
115 goto out;
116 }
117 }
118 }
119
120 int sock = -1;
121 if (pw_name == NULL)
122 {
123 sock = __nscd_open_socket (key, keylen, type, &pw_resp,
124 sizeof (pw_resp));
125 if (sock == -1)
126 {
127 __nss_not_use_nscd_passwd = 1;
128 goto out;
129 }
130 }
131
132 /* No value found so far. */
133 *result = NULL;
134
135 if (__glibc_unlikely (pw_resp.found == -1))
136 {
137 /* The daemon does not cache this database. */
138 __nss_not_use_nscd_passwd = 1;
139 goto out_close;
140 }
141
142 if (pw_resp.found == 1)
143 {
144 /* Set the information we already have. */
145 resultbuf->pw_uid = pw_resp.pw_uid;
146 resultbuf->pw_gid = pw_resp.pw_gid;
147
148 char *p = buffer;
149 /* get pw_name */
150 resultbuf->pw_name = p;
151 p += pw_resp.pw_name_len;
152 /* get pw_passwd */
153 resultbuf->pw_passwd = p;
154 p += pw_resp.pw_passwd_len;
155 /* get pw_gecos */
156 resultbuf->pw_gecos = p;
157 p += pw_resp.pw_gecos_len;
158 /* get pw_dir */
159 resultbuf->pw_dir = p;
160 p += pw_resp.pw_dir_len;
161 /* get pw_pshell */
162 resultbuf->pw_shell = p;
163 p += pw_resp.pw_shell_len;
164
165 ssize_t total = p - buffer;
166 if (__glibc_unlikely (pw_name + total > recend))
167 goto out_close;
168 if (__glibc_unlikely (buflen < total))
169 {
170 __set_errno (ERANGE);
171 retval = ERANGE;
172 goto out_close;
173 }
174
175 retval = 0;
176 if (pw_name == NULL)
177 {
178 ssize_t nbytes = __readall (sock, buffer, total);
179
180 if (__glibc_unlikely (nbytes != total))
181 {
182 /* The `errno' to some value != ERANGE. */
183 __set_errno (ENOENT);
184 retval = ENOENT;
185 }
186 else
187 *result = resultbuf;
188 }
189 else
190 {
191 /* Copy the various strings. */
192 memcpy (resultbuf->pw_name, pw_name, total);
193
194 /* Try to detect corrupt databases. */
195 if (resultbuf->pw_name[pw_resp.pw_name_len - 1] != '\0'
196 || resultbuf->pw_passwd[pw_resp.pw_passwd_len - 1] != '\0'
197 || resultbuf->pw_gecos[pw_resp.pw_gecos_len - 1] != '\0'
198 || resultbuf->pw_dir[pw_resp.pw_dir_len - 1] != '\0'
199 || resultbuf->pw_shell[pw_resp.pw_shell_len - 1] != '\0')
200 {
201 /* We cannot use the database. */
202 retval = mapped->head->gc_cycle != gc_cycle ? -2 : -1;
203 goto out_close;
204 }
205
206 *result = resultbuf;
207 }
208 }
209 else
210 {
211 /* Set errno to 0 to indicate no error, just no found record. */
212 __set_errno (0);
213 /* Even though we have not found anything, the result is zero. */
214 retval = 0;
215 }
216
217 out_close:
218 if (sock != -1)
219 __close_nocancel_nostatus (sock);
220 out:
221 if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0)
222 {
223 /* When we come here this means there has been a GC cycle while we
224 were looking for the data. This means the data might have been
225 inconsistent. Retry if possible. */
226 if ((gc_cycle & 1) != 0 || ++nretries == 5 || retval == -1)
227 {
228 /* nscd is just running gc now. Disable using the mapping. */
229 if (atomic_fetch_add_relaxed (&mapped->counter, -1) == 1)
230 __nscd_unmap (mapped);
231 mapped = NO_MAPPING;
232 }
233
234 if (retval != -1)
235 goto retry;
236 }
237
238 return retval;
239 }