1/* Initgroups handling in nss_files module.
2 Copyright (C) 2011-2020 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
31NSS_DECLARE_MODULE_FUNCTIONS (files)
32
33enum nss_status
34_nss_files_initgroups_dyn (const char *user, gid_t group, long int *start,
35 long int *size, gid_t **groupsp, long int limit,
36 int *errnop)
37{
38 FILE *stream = __nss_files_fopen ("/etc/group");
39 if (stream == NULL)
40 {
41 *errnop = errno;
42 return *errnop == ENOMEM ? NSS_STATUS_TRYAGAIN : NSS_STATUS_UNAVAIL;
43 }
44
45 char *line = NULL;
46 size_t linelen = 0;
47 enum nss_status status = NSS_STATUS_SUCCESS;
48 bool any = false;
49
50 struct scratch_buffer tmpbuf;
51 scratch_buffer_init (&tmpbuf);
52
53 gid_t *groups = *groupsp;
54
55 /* We have to iterate over the entire file. */
56 while (1)
57 {
58 fpos_t pos;
59 fgetpos (stream, &pos);
60 ssize_t n = getline (&line, &linelen, stream);
61 if (n < 0)
62 {
63 if (! feof_unlocked (stream))
64 status = ((*errnop = errno) == ENOMEM
65 ? NSS_STATUS_TRYAGAIN : NSS_STATUS_UNAVAIL);
66 break;
67 }
68
69 struct group grp;
70 int res = _nss_files_parse_grent (line, &grp,
71 tmpbuf.data, tmpbuf.length, errnop);
72 if (res == -1)
73 {
74 if (!scratch_buffer_grow (&tmpbuf))
75 {
76 *errnop = ENOMEM;
77 status = NSS_STATUS_TRYAGAIN;
78 goto out;
79 }
80 /* Reread current line, the parser has clobbered it. */
81 fsetpos (stream, &pos);
82 continue;
83 }
84
85 if (res > 0 && grp.gr_gid != group)
86 for (char **m = grp.gr_mem; *m != NULL; ++m)
87 if (strcmp (*m, user) == 0)
88 {
89 /* Matches user. Insert this group. */
90 if (*start == *size)
91 {
92 /* Need a bigger buffer. */
93 if (limit > 0 && *size == limit)
94 /* We reached the maximum. */
95 goto out;
96
97 long int newsize;
98 if (limit <= 0)
99 newsize = 2 * *size;
100 else
101 newsize = MIN (limit, 2 * *size);
102
103 gid_t *newgroups = realloc (groups,
104 newsize * sizeof (*groups));
105 if (newgroups == NULL)
106 {
107 *errnop = ENOMEM;
108 status = NSS_STATUS_TRYAGAIN;
109 goto out;
110 }
111 *groupsp = groups = newgroups;
112 *size = newsize;
113 }
114
115 groups[*start] = grp.gr_gid;
116 *start += 1;
117 any = true;
118
119 break;
120 }
121 }
122
123 out:
124 /* Free memory. */
125 scratch_buffer_free (&tmpbuf);
126 free (line);
127
128 fclose (stream);
129
130 return status == NSS_STATUS_SUCCESS && !any ? NSS_STATUS_NOTFOUND : status;
131}
132