1 /* Initgroups handling in nss_files module.
2 Copyright (C) 2011-2021 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
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 <errno.h>
20 #include <grp.h>
21 #include <nss.h>
22 #include <stdio_ext.h>
23 #include <string.h>
24 #include <sys/param.h>
25 #include <stdbool.h>
26 #include <stdlib.h>
27 #include <scratch_buffer.h>
28 #include <nss.h>
29 #include <nss_files.h>
30
31 enum nss_status
_nss_files_initgroups_dyn(const char * user,gid_t group,long int * start,long int * size,gid_t ** groupsp,long int limit,int * errnop)32 _nss_files_initgroups_dyn (const char *user, gid_t group, long int *start,
33 long int *size, gid_t **groupsp, long int limit,
34 int *errnop)
35 {
36 FILE *stream = __nss_files_fopen ("/etc/group");
37 if (stream == NULL)
38 {
39 *errnop = errno;
40 return *errnop == ENOMEM ? NSS_STATUS_TRYAGAIN : NSS_STATUS_UNAVAIL;
41 }
42
43 char *line = NULL;
44 size_t linelen = 0;
45 enum nss_status status = NSS_STATUS_SUCCESS;
46 bool any = false;
47
48 struct scratch_buffer tmpbuf;
49 scratch_buffer_init (&tmpbuf);
50
51 gid_t *groups = *groupsp;
52
53 /* We have to iterate over the entire file. */
54 while (1)
55 {
56 fpos_t pos;
57 fgetpos (stream, &pos);
58 ssize_t n = __getline (&line, &linelen, stream);
59 if (n < 0)
60 {
61 if (! __feof_unlocked (stream))
62 status = ((*errnop = errno) == ENOMEM
63 ? NSS_STATUS_TRYAGAIN : NSS_STATUS_UNAVAIL);
64 break;
65 }
66
67 struct group grp;
68 int res = _nss_files_parse_grent (line, &grp,
69 tmpbuf.data, tmpbuf.length, errnop);
70 if (res == -1)
71 {
72 if (!scratch_buffer_grow (&tmpbuf))
73 {
74 *errnop = ENOMEM;
75 status = NSS_STATUS_TRYAGAIN;
76 goto out;
77 }
78 /* Reread current line, the parser has clobbered it. */
79 fsetpos (stream, &pos);
80 continue;
81 }
82
83 if (res > 0 && grp.gr_gid != group)
84 for (char **m = grp.gr_mem; *m != NULL; ++m)
85 if (strcmp (*m, user) == 0)
86 {
87 /* Matches user. Insert this group. */
88 if (*start == *size)
89 {
90 /* Need a bigger buffer. */
91 if (limit > 0 && *size == limit)
92 /* We reached the maximum. */
93 goto out;
94
95 long int newsize;
96 if (limit <= 0)
97 newsize = 2 * *size;
98 else
99 newsize = MIN (limit, 2 * *size);
100
101 gid_t *newgroups = realloc (groups,
102 newsize * sizeof (*groups));
103 if (newgroups == NULL)
104 {
105 *errnop = ENOMEM;
106 status = NSS_STATUS_TRYAGAIN;
107 goto out;
108 }
109 *groupsp = groups = newgroups;
110 *size = newsize;
111 }
112
113 groups[*start] = grp.gr_gid;
114 *start += 1;
115 any = true;
116
117 break;
118 }
119 }
120
121 out:
122 /* Free memory. */
123 scratch_buffer_free (&tmpbuf);
124 free (line);
125
126 fclose (stream);
127
128 return status == NSS_STATUS_SUCCESS && !any ? NSS_STATUS_NOTFOUND : status;
129 }
130 libc_hidden_def (_nss_files_initgroups_dyn)
131