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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 <string.h>
33#include <sys/mman.h>
34#include <unistd.h>
35
36extern "C" {
37
38#define GRDB_STR_MAX_LEN 256
39
40struct group_with_strings : public group {
41 char name_buffer[GRDB_STR_MAX_LEN];
42 char passwd_buffer[GRDB_STR_MAX_LEN];
43 char* members[32];
44 char members_buffer[32][32];
45};
46
47static FILE* __grdb_stream = nullptr;
48static unsigned __grdb_line_number = 0;
49static struct group_with_strings* __grdb_entry = nullptr;
50
51void setgrent()
52{
53 __grdb_line_number = 0;
54 if (__grdb_stream) {
55 rewind(__grdb_stream);
56 } else {
57 __grdb_stream = fopen("/etc/group", "r");
58 if (!__grdb_stream) {
59 perror("open /etc/group");
60 }
61 assert(__grdb_stream);
62 __grdb_entry = (struct group_with_strings*)mmap_with_name(nullptr, getpagesize(), PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0, "setgrent");
63 }
64}
65
66void endgrent()
67{
68 __grdb_line_number = 0;
69 if (__grdb_stream) {
70 fclose(__grdb_stream);
71 __grdb_stream = nullptr;
72 }
73 if (__grdb_entry) {
74 munmap(__grdb_entry, getpagesize());
75 __grdb_entry = nullptr;
76 }
77}
78
79struct group* getgrgid(gid_t gid)
80{
81 setgrent();
82 while (auto* gr = getgrent()) {
83 if (gr->gr_gid == gid)
84 return gr;
85 }
86 return nullptr;
87}
88
89struct group* getgrnam(const char* name)
90{
91 setgrent();
92 while (auto* gr = getgrent()) {
93 if (!strcmp(gr->gr_name, name))
94 return gr;
95 }
96 return nullptr;
97}
98
99struct group* getgrent()
100{
101 if (!__grdb_stream)
102 setgrent();
103
104 assert(__grdb_stream);
105 if (feof(__grdb_stream))
106 return nullptr;
107
108next_entry:
109 char buffer[1024];
110 ++__grdb_line_number;
111 char* s = fgets(buffer, sizeof(buffer), __grdb_stream);
112 if (!s)
113 return nullptr;
114 assert(__grdb_stream);
115 if (feof(__grdb_stream))
116 return nullptr;
117 String line(s, Chomp);
118 auto parts = line.split(':', true);
119 if (parts.size() != 4) {
120 fprintf(stderr, "getgrent(): Malformed entry on line %u: '%s' has %zu parts\n", __grdb_line_number, line.characters(), parts.size());
121 goto next_entry;
122 }
123 auto& e_name = parts[0];
124 auto& e_passwd = parts[1];
125 auto& e_gid_string = parts[2];
126 auto& e_members_string = parts[3];
127 bool ok;
128 gid_t e_gid = e_gid_string.to_uint(ok);
129 if (!ok) {
130 fprintf(stderr, "getgrent(): Malformed GID on line %u\n", __grdb_line_number);
131 goto next_entry;
132 }
133 auto members = e_members_string.split(',');
134 __grdb_entry->gr_gid = e_gid;
135 __grdb_entry->gr_name = __grdb_entry->name_buffer;
136 __grdb_entry->gr_passwd = __grdb_entry->passwd_buffer;
137 for (size_t i = 0; i < members.size(); ++i) {
138 __grdb_entry->members[i] = __grdb_entry->members_buffer[i];
139 strcpy(__grdb_entry->members_buffer[i], members[i].characters());
140 }
141 __grdb_entry->members[members.size()] = nullptr;
142 __grdb_entry->gr_mem = __grdb_entry->members;
143 strncpy(__grdb_entry->name_buffer, e_name.characters(), GRDB_STR_MAX_LEN);
144 strncpy(__grdb_entry->passwd_buffer, e_passwd.characters(), GRDB_STR_MAX_LEN);
145 return __grdb_entry;
146}
147
148int initgroups(const char* user, gid_t extra_gid)
149{
150 size_t count = 0;
151 gid_t gids[32];
152 bool extra_gid_added = false;
153 setgrent();
154 while (auto* gr = getgrent()) {
155 for (auto* mem = gr->gr_mem; *mem; ++mem) {
156 if (!strcmp(*mem, user)) {
157 gids[count++] = gr->gr_gid;
158 if (gr->gr_gid == extra_gid)
159 extra_gid_added = true;
160 break;
161 }
162 }
163 }
164 endgrent();
165 if (!extra_gid_added)
166 gids[count++] = extra_gid;
167 return setgroups(count, gids);
168}
169}