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Serenity Operating System
1/*
2 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 *
8 * 1. Redistributions of source code must retain the above copyright notice, this
9 * list of conditions and the following disclaimer.
10 *
11 * 2. Redistributions in binary form must reproduce the above copyright notice,
12 * this list of conditions and the following disclaimer in the documentation
13 * and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
16 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
18 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
21 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
22 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
23 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
24 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include <AK/String.h>
28#include <AK/Vector.h>
29#include <grp.h>
30#include <stdio.h>
31#include <stdlib.h>
32#include <sys/mman.h>
33#include <unistd.h>
34
35extern "C" {
36
37#define GRDB_STR_MAX_LEN 256
38
39struct group_with_strings : public group {
40 char name_buffer[GRDB_STR_MAX_LEN];
41 char passwd_buffer[GRDB_STR_MAX_LEN];
42 char* members[32];
43 char members_buffer[32][32];
44};
45
46static FILE* __grdb_stream = nullptr;
47static unsigned __grdb_line_number = 0;
48static struct group_with_strings* __grdb_entry = nullptr;
49
50void setgrent()
51{
52 __grdb_line_number = 0;
53 if (__grdb_stream) {
54 rewind(__grdb_stream);
55 } else {
56 __grdb_stream = fopen("/etc/group", "r");
57 if (!__grdb_stream) {
58 perror("open /etc/group");
59 }
60 assert(__grdb_stream);
61 __grdb_entry = (struct group_with_strings*)mmap_with_name(nullptr, getpagesize(), PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0, "setgrent");
62 }
63}
64
65void endgrent()
66{
67 __grdb_line_number = 0;
68 if (__grdb_stream) {
69 fclose(__grdb_stream);
70 __grdb_stream = nullptr;
71 }
72 if (__grdb_entry) {
73 munmap(__grdb_entry, getpagesize());
74 __grdb_entry = nullptr;
75 }
76}
77
78struct group* getgrgid(gid_t gid)
79{
80 setgrent();
81 while (auto* gr = getgrent()) {
82 if (gr->gr_gid == gid)
83 return gr;
84 }
85 return nullptr;
86}
87
88struct group* getgrnam(const char* name)
89{
90 setgrent();
91 while (auto* gr = getgrent()) {
92 if (!strcmp(gr->gr_name, name))
93 return gr;
94 }
95 return nullptr;
96}
97
98struct group* getgrent()
99{
100 if (!__grdb_stream)
101 setgrent();
102
103 assert(__grdb_stream);
104 if (feof(__grdb_stream))
105 return nullptr;
106
107next_entry:
108 char buffer[1024];
109 ++__grdb_line_number;
110 char* s = fgets(buffer, sizeof(buffer), __grdb_stream);
111 if (!s)
112 return nullptr;
113 assert(__grdb_stream);
114 if (feof(__grdb_stream))
115 return nullptr;
116 String line(s, Chomp);
117 auto parts = line.split(':', true);
118 if (parts.size() != 4) {
119 fprintf(stderr, "getgrent(): Malformed entry on line %u: '%s' has %zu parts\n", __grdb_line_number, line.characters(), parts.size());
120 goto next_entry;
121 }
122 auto& e_name = parts[0];
123 auto& e_passwd = parts[1];
124 auto& e_gid_string = parts[2];
125 auto& e_members_string = parts[3];
126 bool ok;
127 gid_t e_gid = e_gid_string.to_uint(ok);
128 if (!ok) {
129 fprintf(stderr, "getgrent(): Malformed GID on line %u\n", __grdb_line_number);
130 goto next_entry;
131 }
132 auto members = e_members_string.split(',');
133 __grdb_entry->gr_gid = e_gid;
134 __grdb_entry->gr_name = __grdb_entry->name_buffer;
135 __grdb_entry->gr_passwd = __grdb_entry->passwd_buffer;
136 for (size_t i = 0; i < members.size(); ++i) {
137 __grdb_entry->members[i] = __grdb_entry->members_buffer[i];
138 strcpy(__grdb_entry->members_buffer[i], members[i].characters());
139 }
140 __grdb_entry->members[members.size()] = nullptr;
141 __grdb_entry->gr_mem = __grdb_entry->members;
142 strncpy(__grdb_entry->name_buffer, e_name.characters(), GRDB_STR_MAX_LEN);
143 strncpy(__grdb_entry->passwd_buffer, e_passwd.characters(), GRDB_STR_MAX_LEN);
144 return __grdb_entry;
145}
146
147int initgroups(const char* user, gid_t extra_gid)
148{
149 size_t count = 0;
150 gid_t gids[32];
151 bool extra_gid_added = false;
152 setgrent();
153 while (auto* gr = getgrent()) {
154 for (auto* mem = gr->gr_mem; *mem; ++mem) {
155 if (!strcmp(*mem, user)) {
156 gids[count++] = gr->gr_gid;
157 if (gr->gr_gid == extra_gid)
158 extra_gid_added = true;
159 break;
160 }
161 }
162 }
163 endgrent();
164 if (!extra_gid_added)
165 gids[count++] = extra_gid;
166 return setgroups(count, gids);
167}
168}