1 /* mknod -- make special files
2 Copyright (C) 1990-2023 Free Software Foundation, Inc.
3
4 This program is free software: you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation, either version 3 of the License, or
7 (at your option) any later version.
8
9 This program 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
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <https://www.gnu.org/licenses/>. */
16
17 /* Written by David MacKenzie <djm@ai.mit.edu> */
18
19 #include <config.h>
20 #include <stdio.h>
21 #include <getopt.h>
22 #include <sys/types.h>
23 #include <selinux/label.h>
24
25 #include "system.h"
26 #include "modechange.h"
27 #include "quote.h"
28 #include "selinux.h"
29 #include "smack.h"
30 #include "xstrtol.h"
31
32 /* The official name of this program (e.g., no 'g' prefix). */
33 #define PROGRAM_NAME "mknod"
34
35 #define AUTHORS proper_name ("David MacKenzie")
36
37 static struct option const longopts[] =
38 {
39 {GETOPT_SELINUX_CONTEXT_OPTION_DECL},
40 {"mode", required_argument, nullptr, 'm'},
41 {GETOPT_HELP_OPTION_DECL},
42 {GETOPT_VERSION_OPTION_DECL},
43 {nullptr, 0, nullptr, 0}
44 };
45
46 void
47 usage (int status)
48 {
49 if (status != EXIT_SUCCESS)
50 emit_try_help ();
51 else
52 {
53 printf (_("Usage: %s [OPTION]... NAME TYPE [MAJOR MINOR]\n"),
54 program_name);
55 fputs (_("\
56 Create the special file NAME of the given TYPE.\n\
57 "), stdout);
58
59 emit_mandatory_arg_note ();
60
61 fputs (_("\
62 -m, --mode=MODE set file permission bits to MODE, not a=rw - umask\n\
63 "), stdout);
64 fputs (_("\
65 -Z set the SELinux security context to default type\n\
66 --context[=CTX] like -Z, or if CTX is specified then set the SELinux\n\
67 or SMACK security context to CTX\n\
68 "), stdout);
69 fputs (HELP_OPTION_DESCRIPTION, stdout);
70 fputs (VERSION_OPTION_DESCRIPTION, stdout);
71 fputs (_("\
72 \n\
73 Both MAJOR and MINOR must be specified when TYPE is b, c, or u, and they\n\
74 must be omitted when TYPE is p. If MAJOR or MINOR begins with 0x or 0X,\n\
75 it is interpreted as hexadecimal; otherwise, if it begins with 0, as octal;\n\
76 otherwise, as decimal. TYPE may be:\n\
77 "), stdout);
78 fputs (_("\
79 \n\
80 b create a block (buffered) special file\n\
81 c, u create a character (unbuffered) special file\n\
82 p create a FIFO\n\
83 "), stdout);
84 printf (USAGE_BUILTIN_WARNING, PROGRAM_NAME);
85 emit_ancillary_info (PROGRAM_NAME);
86 }
87 exit (status);
88 }
89
90 int
91 main (int argc, char **argv)
92 {
93 mode_t newmode;
94 char const *specified_mode = nullptr;
95 int optc;
96 size_t expected_operands;
97 mode_t node_type;
98 char const *scontext = nullptr;
99 struct selabel_handle *set_security_context = nullptr;
100
101 initialize_main (&argc, &argv);
102 set_program_name (argv[0]);
103 setlocale (LC_ALL, "");
104 bindtextdomain (PACKAGE, LOCALEDIR);
105 textdomain (PACKAGE);
106
107 atexit (close_stdout);
108
109 while ((optc = getopt_long (argc, argv, "m:Z", longopts, nullptr)) != -1)
110 {
111 switch (optc)
112 {
113 case 'm':
114 specified_mode = optarg;
115 break;
116 case 'Z':
117 if (is_smack_enabled ())
118 {
119 /* We don't yet support -Z to restore context with SMACK. */
120 scontext = optarg;
121 }
122 else if (is_selinux_enabled () > 0)
123 {
124 if (optarg)
125 scontext = optarg;
126 else
127 {
128 set_security_context = selabel_open (SELABEL_CTX_FILE,
129 nullptr, 0);
130 if (! set_security_context)
131 error (0, errno, _("warning: ignoring --context"));
132 }
133 }
134 else if (optarg)
135 {
136 error (0, 0,
137 _("warning: ignoring --context; "
138 "it requires an SELinux/SMACK-enabled kernel"));
139 }
140 break;
141 case_GETOPT_HELP_CHAR;
142 case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
143 default:
144 usage (EXIT_FAILURE);
145 }
146 }
147
148 newmode = MODE_RW_UGO;
149 if (specified_mode)
150 {
151 mode_t umask_value;
152 struct mode_change *change = mode_compile (specified_mode);
153 if (!change)
154 error (EXIT_FAILURE, 0, _("invalid mode"));
155 umask_value = umask (0);
156 umask (umask_value);
157 newmode = mode_adjust (newmode, false, umask_value, change, nullptr);
158 free (change);
159 if (newmode & ~S_IRWXUGO)
160 error (EXIT_FAILURE, 0,
161 _("mode must specify only file permission bits"));
162 }
163
164 /* If the number of arguments is 0 or 1,
165 or (if it's 2 or more and the second one starts with 'p'), then there
166 must be exactly two operands. Otherwise, there must be four. */
167 expected_operands = (argc <= optind
168 || (optind + 1 < argc && argv[optind + 1][0] == 'p')
169 ? 2 : 4);
170
171 if (argc - optind < expected_operands)
172 {
173 if (argc <= optind)
174 error (0, 0, _("missing operand"));
175 else
176 error (0, 0, _("missing operand after %s"), quote (argv[argc - 1]));
177 if (expected_operands == 4 && argc - optind == 2)
178 fprintf (stderr, "%s\n",
179 _("Special files require major and minor device numbers."));
180 usage (EXIT_FAILURE);
181 }
182
183 if (expected_operands < argc - optind)
184 {
185 error (0, 0, _("extra operand %s"),
186 quote (argv[optind + expected_operands]));
187 if (expected_operands == 2 && argc - optind == 4)
188 fprintf (stderr, "%s\n",
189 _("Fifos do not have major and minor device numbers."));
190 usage (EXIT_FAILURE);
191 }
192
193 if (scontext)
194 {
195 int ret = 0;
196 if (is_smack_enabled ())
197 ret = smack_set_label_for_self (scontext);
198 else
199 ret = setfscreatecon (scontext);
200
201 if (ret < 0)
202 error (EXIT_FAILURE, errno,
203 _("failed to set default file creation context to %s"),
204 quote (scontext));
205 }
206
207 /* Only check the first character, to allow mnemonic usage like
208 'mknod /dev/rst0 character 18 0'. */
209
210 switch (argv[optind + 1][0])
211 {
212 case 'b': /* 'block' or 'buffered' */
213 #ifndef S_IFBLK
214 error (EXIT_FAILURE, 0, _("block special files not supported"));
215 #else
216 node_type = S_IFBLK;
217 #endif
218 goto block_or_character;
219
220 case 'c': /* 'character' */
221 case 'u': /* 'unbuffered' */
222 #ifndef S_IFCHR
223 error (EXIT_FAILURE, 0, _("character special files not supported"));
224 #else
225 node_type = S_IFCHR;
226 #endif
227 goto block_or_character;
228
229 block_or_character:
230 {
231 char const *s_major = argv[optind + 2];
232 char const *s_minor = argv[optind + 3];
233 uintmax_t i_major, i_minor;
234 dev_t device;
235
236 if (xstrtoumax (s_major, nullptr, 0, &i_major, "") != LONGINT_OK
237 || i_major != (major_t) i_major)
238 error (EXIT_FAILURE, 0,
239 _("invalid major device number %s"), quote (s_major));
240
241 if (xstrtoumax (s_minor, nullptr, 0, &i_minor, "") != LONGINT_OK
242 || i_minor != (minor_t) i_minor)
243 error (EXIT_FAILURE, 0,
244 _("invalid minor device number %s"), quote (s_minor));
245
246 device = makedev (i_major, i_minor);
247 #ifdef NODEV
248 if (device == NODEV)
249 error (EXIT_FAILURE, 0, _("invalid device %s %s"),
250 s_major, s_minor);
251 #endif
252
253 if (set_security_context)
254 defaultcon (set_security_context, argv[optind], node_type);
255
256 if (mknod (argv[optind], newmode | node_type, device) != 0)
257 error (EXIT_FAILURE, errno, "%s", quotef (argv[optind]));
258 }
259 break;
260
261 case 'p': /* 'pipe' */
262 if (set_security_context)
263 defaultcon (set_security_context, argv[optind], S_IFIFO);
264 if (mkfifo (argv[optind], newmode) != 0)
265 error (EXIT_FAILURE, errno, "%s", quotef (argv[optind]));
266 break;
267
268 default:
269 error (0, 0, _("invalid device type %s"), quote (argv[optind + 1]));
270 usage (EXIT_FAILURE);
271 }
272
273 if (specified_mode && lchmod (argv[optind], newmode) != 0)
274 error (EXIT_FAILURE, errno, _("cannot set permissions of %s"),
275 quoteaf (argv[optind]));
276
277 return EXIT_SUCCESS;
278 }