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1 | /* -*-c-*- |
2 | * |
194363d4 |
3 | * $Id: tmpdir.c,v 1.5 2004/04/08 01:36:22 mdw Exp $ |
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4 | * |
5 | * Choose and check temporary directories |
6 | * |
7 | * (c) 1999 Mark Wooding |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of chkpath. |
13 | * |
14 | * chkpath is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU General Public License as published by |
16 | * the Free Software Foundation; either version 2 of the License, or |
17 | * (at your option) any later version. |
18 | * |
19 | * chkpath is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU General Public License |
25 | * along with chkpath; if not, write to the Free Software Foundation, |
26 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
27 | */ |
28 | |
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29 | /*----- Header files ------------------------------------------------------*/ |
30 | |
31 | #include <errno.h> |
32 | #include <stdio.h> |
33 | #include <stdlib.h> |
34 | #include <string.h> |
35 | |
36 | #include <sys/types.h> |
37 | #include <sys/stat.h> |
38 | #include <unistd.h> |
39 | #include <pwd.h> |
40 | |
41 | #include <mLib/alloc.h> |
42 | #include <mLib/dstr.h> |
43 | #include <mLib/mdwopt.h> |
44 | #include <mLib/quis.h> |
45 | #include <mLib/report.h> |
46 | |
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47 | #include "checkpath.h" |
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48 | |
49 | /*----- Static variables --------------------------------------------------*/ |
50 | |
51 | static uid_t me; |
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52 | static struct checkpath cp; |
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53 | static struct passwd *pw; |
54 | |
55 | /*----- Main code ---------------------------------------------------------*/ |
56 | |
57 | /* --- @ok@ --- * |
58 | * |
59 | * Arguments: @const char *p@ = pathname to check |
60 | * @int *f@ = try-to-create flag |
61 | * |
62 | * Returns: Nonzero if the directory is OK |
63 | * |
64 | * Use: Ensures that a directory is OK. If @f@ is a real pointer, |
65 | * and @*f@ is set, then try to create the directory. |
66 | */ |
67 | |
68 | static int ok(const char *p, int *f) |
69 | { |
70 | struct stat st; |
71 | |
72 | /* --- Read the directory status --- */ |
73 | |
74 | if (lstat(p, &st)) { |
75 | |
76 | /* --- Maybe create it if it doesn't exist --- */ |
77 | |
78 | if (errno != ENOENT || !f || !*f) |
79 | return (0); |
80 | if (mkdir(p, 0700)) { |
81 | *f = 0; |
82 | return (0); |
83 | } |
84 | |
85 | /* --- Now read the new status --- * |
86 | * |
87 | * This fixes a race condition between the previous @lstat@ call and |
88 | * the @mkdir@. |
89 | */ |
90 | |
91 | if (lstat(p, &st)) |
92 | return (0); |
93 | } |
94 | |
95 | /* --- Make sure the directory is good --- * |
96 | * |
97 | * It must be a genuine directory (not a link); it must be readable |
98 | * and writable only by its owner, and that owner must be me. |
99 | */ |
100 | |
101 | if (S_ISDIR(st.st_mode) && (st.st_mode & 0777) == 0700 && st.st_uid == me) |
102 | return (1); |
103 | return (0); |
104 | } |
105 | |
106 | /* --- @trytmp@ --- * |
107 | * |
108 | * Arguments: @const char *parent@ = parent directory name |
109 | * @const char *base@ = subdirectory base name |
110 | * |
111 | * Returns: Pointer to directory name, or null. (String needs freeing.) |
112 | * |
113 | * Use: Tries to find or create an appropriate temporary directory. |
114 | */ |
115 | |
116 | static char *trytmp(const char *parent, const char *base) |
117 | { |
118 | static char c[] = { "0123456789" |
119 | "abcdefghijklmnopqrstuvwxyz" |
120 | "ABCDEFGHIJKLMNOPQRSTUVWXYZ" }; |
121 | char *p, *q; |
122 | char *qq; |
72462155 |
123 | dstr d = DSTR_INIT; |
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124 | int createflag = 1; |
125 | |
126 | /* --- Make sure the parent directory is sane --- * |
127 | * |
128 | * Must make sure that all the lead-up to the temporary directory is safe. |
129 | * Otherwise other people can play with symlinks or rename directories |
130 | * after I've done all this careful work to make the endpoint directory |
131 | * safe. |
132 | */ |
133 | |
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134 | if (checkpath(parent, &cp)) |
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135 | return (0); |
136 | |
137 | /* --- See whether the trivial version will work --- */ |
138 | |
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139 | dstr_putf(&d, "%s/%s", parent, base); |
140 | if (ok(d.buf, &createflag)) |
141 | goto good; |
142 | |
143 | /* --- Now try with various suffixes --- */ |
144 | |
145 | DENSURE(&d, 4); |
146 | qq = d.buf + d.len; |
147 | *qq++ = '-'; |
148 | |
149 | for (p = c; *p; p++) { |
150 | qq[0] = *p; |
151 | qq[1] = 0; |
152 | if (ok(d.buf, &createflag)) |
153 | goto good; |
154 | for (q = c; *q; q++) { |
155 | qq[1] = *q; |
156 | qq[2] = 0; |
157 | if (ok(d.buf, &createflag)) |
158 | goto good; |
159 | } |
160 | } |
161 | |
162 | /* --- No joy --- */ |
163 | |
164 | dstr_destroy(&d); |
165 | return (0); |
166 | |
167 | good: |
168 | p = xstrdup(d.buf); |
169 | dstr_destroy(&d); |
170 | return (p); |
171 | } |
172 | |
173 | /* --- @fullcheck@ --- * |
174 | * |
175 | * Arguments: @const char *p@ = pointer to path to check |
176 | * |
177 | * Returns: Zero if it's a bad directory. |
178 | * |
179 | * Use: Runs a thorough check on a directory. |
180 | */ |
181 | |
182 | static int fullcheck(const char *p) |
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183 | { return (checkpath(p, &cp) == 0 && ok(p, 0)); } |
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184 | |
185 | /* --- @goodtmp@ --- * |
186 | * |
187 | * Arguments: --- |
188 | * |
189 | * Returns: Pointer to a known-good secure temporary directory, or |
190 | * null. |
191 | * |
192 | * Use: Finds a good place to store temporary files. |
193 | */ |
194 | |
195 | static char *goodtmp(void) |
196 | { |
197 | char *p, *q; |
198 | |
199 | /* --- First of all, try the user's current choice --- */ |
200 | |
201 | if ((p = getenv("TMPDIR")) != 0 && fullcheck(p)) |
202 | return (p); |
203 | |
204 | /* --- Try making a directory in `/tmp' --- */ |
205 | |
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206 | if ((q = trytmp("/tmp", pw->pw_name)) != 0) |
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207 | return (q); |
208 | |
209 | /* --- That failed: try a directory in the user's home --- */ |
210 | |
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211 | if ((q = trytmp(pw->pw_dir, "tmp")) != 0) |
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212 | return (q); |
213 | |
214 | /* --- Still no joy: give up --- * |
215 | * |
216 | * To be fair, if the user can't find a safe place in his own home |
217 | * directory then he's pretty stuffed. |
218 | */ |
219 | |
220 | return (0); |
221 | } |
222 | |
223 | /* --- @usage@ --- */ |
224 | |
225 | static void usage(FILE *fp) |
5dd99356 |
226 | { fprintf(fp, "Usage: %s [-bc] [-v PATH]\n", QUIS); } |
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227 | |
228 | /* --- @version@ --- */ |
229 | |
230 | static void version(FILE *fp) |
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231 | { fprintf(fp, "%s version %s\n", QUIS, VERSION); } |
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232 | |
233 | /* --- @help@ --- */ |
234 | |
235 | static void help(FILE *fp) |
236 | { |
237 | version(fp); |
238 | putc('\n', fp); |
239 | usage(fp); |
240 | fputs("\n\ |
241 | Sets a suitable and secure temporary directory, or checks that a given\n\ |
242 | directory is suitable for use with temporary files. A directory is\n\ |
243 | considered good for a particular user if it's readable and writable only\n\ |
244 | by that user, and if all its parents are modifiable only by the user or\n\ |
245 | root.\n\ |
246 | \n\ |
247 | Options supported:\n\ |
248 | \n\ |
249 | -h, --help Display this help text.\n\ |
250 | -V, --version Display the program's version number.\n\ |
251 | -u, --usage Display a terse usage summary.\n\ |
252 | \n\ |
253 | -b, --bourne Output a `TMPDIR' setting for Bourne shell users.\n\ |
254 | -c, --cshell Output a `TMPDIR' setting for C shell users.\n\ |
255 | -v, --verify PATH Check whether PATH is good, setting exit status.\n\ |
256 | \n\ |
257 | The default action is to examine the caller's shell and output a suitable\n\ |
258 | setting for that shell type.\n\ |
259 | ", |
260 | fp); |
261 | } |
262 | |
263 | /* --- @main@ --- * |
264 | * |
265 | * Arguments: @int argc@ = number of command line arguments |
266 | * @char *argv[]@ = the actual argument strings |
267 | * |
268 | * Returns: Zero if all went well, else nonzero. |
269 | * |
270 | * Use: Performs helpful operations on temporary directories. |
271 | */ |
272 | |
273 | int main(int argc, char *argv[]) |
274 | { |
275 | int shell = 0; |
276 | int duff = 0; |
277 | |
278 | enum { |
279 | sh_unknown, |
280 | sh_bourne, |
281 | sh_csh |
282 | }; |
283 | |
284 | /* --- Initialize variables --- */ |
285 | |
286 | ego(argv[0]); |
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287 | me = geteuid(); |
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288 | cp.cp_what = CP_WRWORLD | CP_WRGRP | CP_WROTHUSR | CP_STICKYOK; |
289 | cp.cp_verbose = 0; |
290 | cp.cp_report = 0; |
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291 | checkpath_setids(&cp); |
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292 | pw = getpwuid(me); |
293 | if (!pw) |
294 | die(1, "you don't exist"); |
295 | |
296 | /* --- Parse arguments --- */ |
297 | |
298 | for (;;) { |
299 | static struct option opts[] = { |
300 | { "help", 0, 0, 'h' }, |
301 | { "version", 0, 0, 'V' }, |
302 | { "usage", 0, 0, 'u' }, |
303 | { "bourne", 0, 0, 'b' }, |
304 | { "cshell", 0, 0, 'c' }, |
cef4f797 |
305 | { "verify", OPTF_ARGREQ, 0, 'v' }, |
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306 | { 0, 0, 0, 0 } |
307 | }; |
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308 | int i = mdwopt(argc, argv, "hVu" "bcv:", opts, 0, 0, 0); |
efa7a97b |
309 | |
310 | if (i < 0) |
311 | break; |
312 | switch (i) { |
313 | case 'h': |
314 | help(stdout); |
315 | exit(0); |
316 | case 'V': |
317 | version(stdout); |
318 | exit(0); |
319 | case 'u': |
320 | usage(stdout); |
321 | exit(0); |
322 | case 'b': |
323 | shell = sh_bourne; |
324 | break; |
325 | case 'c': |
326 | shell = sh_csh; |
327 | break; |
328 | case 'v': |
329 | return (!fullcheck(optarg)); |
330 | break; |
331 | default: |
332 | duff = 1; |
333 | break; |
334 | } |
335 | } |
336 | |
337 | if (duff || optind != argc) { |
338 | usage(stderr); |
339 | exit(1); |
340 | } |
341 | |
342 | /* --- Choose a shell --- */ |
343 | |
344 | if (!shell) { |
345 | char *p; |
346 | if (!(p = getenv("SHELL"))) |
347 | p = pw->pw_shell; |
348 | if (strstr(p, "csh")) |
349 | shell = sh_csh; |
350 | else |
351 | shell = sh_bourne; |
352 | } |
353 | |
354 | /* --- Start the checking --- */ |
355 | |
356 | { |
357 | char *p = goodtmp(); |
358 | if (!p) |
359 | die(1, "no good tmp directory"); |
360 | switch (shell) { |
361 | case sh_bourne: |
362 | printf("TMPDIR=\"%s\"; export TMPDIR\n", p); |
363 | break; |
364 | case sh_csh: |
365 | printf("setenv TMPDIR \"%s\"\n", p); |
366 | break; |
367 | } |
368 | } |
369 | |
370 | return (0); |
371 | } |
372 | |
373 | /*----- That's all, folks -------------------------------------------------*/ |