| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * Choose and check temporary directories |
| 4 | * |
| 5 | * (c) 1999 Mark Wooding |
| 6 | */ |
| 7 | |
| 8 | /*----- Licensing notice --------------------------------------------------* |
| 9 | * |
| 10 | * This file is part of chkpath. |
| 11 | * |
| 12 | * chkpath is free software; you can redistribute it and/or modify |
| 13 | * it under the terms of the GNU General Public License as published by |
| 14 | * the Free Software Foundation; either version 2 of the License, or |
| 15 | * (at your option) any later version. |
| 16 | * |
| 17 | * chkpath is distributed in the hope that it will be useful, |
| 18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 20 | * GNU General Public License for more details. |
| 21 | * |
| 22 | * You should have received a copy of the GNU General Public License |
| 23 | * along with chkpath; if not, write to the Free Software Foundation, |
| 24 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
| 25 | */ |
| 26 | |
| 27 | /*----- Header files ------------------------------------------------------*/ |
| 28 | |
| 29 | #include "config.h" |
| 30 | |
| 31 | #include <errno.h> |
| 32 | #include <ctype.h> |
| 33 | #include <stdio.h> |
| 34 | #include <stdlib.h> |
| 35 | #include <string.h> |
| 36 | |
| 37 | #include <sys/types.h> |
| 38 | #include <sys/stat.h> |
| 39 | #include <unistd.h> |
| 40 | #include <pwd.h> |
| 41 | #include <grp.h> |
| 42 | |
| 43 | #include <mLib/alloc.h> |
| 44 | #include <mLib/dstr.h> |
| 45 | #include <mLib/macros.h> |
| 46 | #include <mLib/mdwopt.h> |
| 47 | #include <mLib/quis.h> |
| 48 | #include <mLib/report.h> |
| 49 | |
| 50 | #include "checkpath.h" |
| 51 | #include "utils.h" |
| 52 | |
| 53 | /*----- Static variables --------------------------------------------------*/ |
| 54 | |
| 55 | static uid_t me; |
| 56 | static struct checkpath cp; |
| 57 | static struct passwd *pw; |
| 58 | |
| 59 | /*----- Main code ---------------------------------------------------------*/ |
| 60 | |
| 61 | /* --- @ok@ --- * |
| 62 | * |
| 63 | * Arguments: @const char *p@ = pathname to check |
| 64 | * @int *f@ = try-to-create flag |
| 65 | * |
| 66 | * Returns: Nonzero if the directory is OK |
| 67 | * |
| 68 | * Use: Ensures that a directory is OK. If @f@ is a real pointer, |
| 69 | * and @*f@ is set, then try to create the directory. |
| 70 | */ |
| 71 | |
| 72 | static int ok(const char *p, int *f) |
| 73 | { |
| 74 | struct stat st; |
| 75 | |
| 76 | /* --- Read the directory status --- */ |
| 77 | |
| 78 | if (lstat(p, &st)) { |
| 79 | |
| 80 | /* --- Maybe create it if it doesn't exist --- */ |
| 81 | |
| 82 | if (errno != ENOENT || !f || !*f) |
| 83 | return (0); |
| 84 | if (mkdir(p, 0700)) { |
| 85 | *f = 0; |
| 86 | return (0); |
| 87 | } |
| 88 | |
| 89 | /* --- Now read the new status --- * |
| 90 | * |
| 91 | * This fixes a race condition between the previous @lstat@ call and |
| 92 | * the @mkdir@. |
| 93 | */ |
| 94 | |
| 95 | if (lstat(p, &st)) |
| 96 | return (0); |
| 97 | } |
| 98 | |
| 99 | /* --- Make sure the directory is good --- * |
| 100 | * |
| 101 | * It must be a genuine directory (not a link); it must be readable |
| 102 | * and writable only by its owner, and that owner must be me. |
| 103 | */ |
| 104 | |
| 105 | if (S_ISDIR(st.st_mode) && (st.st_mode & 0777) == 0700 && st.st_uid == me) |
| 106 | return (1); |
| 107 | return (0); |
| 108 | } |
| 109 | |
| 110 | /* --- @trytmp@ --- * |
| 111 | * |
| 112 | * Arguments: @const char *parent@ = parent directory name |
| 113 | * @const char *base@ = subdirectory base name |
| 114 | * |
| 115 | * Returns: Pointer to directory name, or null. (String needs freeing.) |
| 116 | * |
| 117 | * Use: Tries to find or create an appropriate temporary directory. |
| 118 | */ |
| 119 | |
| 120 | static char *trytmp(const char *parent, const char *base) |
| 121 | { |
| 122 | static char c[] = { "0123456789" |
| 123 | "abcdefghijklmnopqrstuvwxyz" |
| 124 | "ABCDEFGHIJKLMNOPQRSTUVWXYZ" }; |
| 125 | char *p, *q; |
| 126 | char *qq; |
| 127 | dstr d = DSTR_INIT; |
| 128 | int createflag = 1; |
| 129 | |
| 130 | /* --- Make sure the parent directory is sane --- * |
| 131 | * |
| 132 | * Must make sure that all the lead-up to the temporary directory is safe. |
| 133 | * Otherwise other people can play with symlinks or rename directories |
| 134 | * after I've done all this careful work to make the endpoint directory |
| 135 | * safe. |
| 136 | */ |
| 137 | |
| 138 | if (checkpath(parent, &cp)) |
| 139 | return (0); |
| 140 | |
| 141 | /* --- See whether the trivial version will work --- */ |
| 142 | |
| 143 | dstr_putf(&d, "%s/%s", parent, base); |
| 144 | if (ok(d.buf, &createflag)) |
| 145 | goto good; |
| 146 | |
| 147 | /* --- Now try with various suffixes --- */ |
| 148 | |
| 149 | DENSURE(&d, 4); |
| 150 | qq = d.buf + d.len; |
| 151 | *qq++ = '-'; |
| 152 | |
| 153 | for (p = c; *p; p++) { |
| 154 | qq[0] = *p; |
| 155 | qq[1] = 0; |
| 156 | if (ok(d.buf, &createflag)) |
| 157 | goto good; |
| 158 | for (q = c; *q; q++) { |
| 159 | qq[1] = *q; |
| 160 | qq[2] = 0; |
| 161 | if (ok(d.buf, &createflag)) |
| 162 | goto good; |
| 163 | } |
| 164 | } |
| 165 | |
| 166 | /* --- No joy --- */ |
| 167 | |
| 168 | dstr_destroy(&d); |
| 169 | return (0); |
| 170 | |
| 171 | good: |
| 172 | p = xstrdup(d.buf); |
| 173 | dstr_destroy(&d); |
| 174 | return (p); |
| 175 | } |
| 176 | |
| 177 | /* --- @fullcheck@ --- * |
| 178 | * |
| 179 | * Arguments: @const char *p@ = pointer to path to check |
| 180 | * |
| 181 | * Returns: Zero if it's a bad directory. |
| 182 | * |
| 183 | * Use: Runs a thorough check on a directory. |
| 184 | */ |
| 185 | |
| 186 | static int fullcheck(const char *p) |
| 187 | { return (checkpath(p, &cp) == 0 && ok(p, 0)); } |
| 188 | |
| 189 | /* --- @goodtmp@ --- * |
| 190 | * |
| 191 | * Arguments: --- |
| 192 | * |
| 193 | * Returns: Pointer to a known-good secure temporary directory, or |
| 194 | * null. |
| 195 | * |
| 196 | * Use: Finds a good place to store temporary files. |
| 197 | */ |
| 198 | |
| 199 | static char *goodtmp(void) |
| 200 | { |
| 201 | char *p, *q; |
| 202 | |
| 203 | /* --- First of all, try the user's current choice --- */ |
| 204 | |
| 205 | if ((p = getenv("TMPDIR")) != 0 && fullcheck(p)) |
| 206 | return (p); |
| 207 | |
| 208 | /* --- Try making a directory in `/tmp' --- */ |
| 209 | |
| 210 | if ((q = trytmp("/tmp", pw->pw_name)) != 0) |
| 211 | return (q); |
| 212 | |
| 213 | /* --- That failed: try a directory in the user's home --- */ |
| 214 | |
| 215 | if ((q = trytmp(pw->pw_dir, "tmp")) != 0) |
| 216 | return (q); |
| 217 | |
| 218 | /* --- Still no joy: give up --- * |
| 219 | * |
| 220 | * To be fair, if the user can't find a safe place in his own home |
| 221 | * directory then he's pretty stuffed. |
| 222 | */ |
| 223 | |
| 224 | return (0); |
| 225 | } |
| 226 | |
| 227 | /* --- @report@ --- */ |
| 228 | |
| 229 | static void report(unsigned what, int verbose, |
| 230 | const char *p, const char *msg, |
| 231 | void *arg) |
| 232 | { moan("%s", msg); } |
| 233 | |
| 234 | /* --- @usage@ --- */ |
| 235 | |
| 236 | static void usage(FILE *fp) |
| 237 | { fprintf(fp, "Usage: %s [-bcv] [-g NAME] [-C PATH]\n", QUIS); } |
| 238 | |
| 239 | /* --- @version@ --- */ |
| 240 | |
| 241 | static void version(FILE *fp) |
| 242 | { fprintf(fp, "%s version %s\n", QUIS, VERSION); } |
| 243 | |
| 244 | /* --- @help@ --- */ |
| 245 | |
| 246 | static void help(FILE *fp) |
| 247 | { |
| 248 | version(fp); |
| 249 | putc('\n', fp); |
| 250 | usage(fp); |
| 251 | fputs("\n\ |
| 252 | Sets a suitable and secure temporary directory, or checks that a given\n\ |
| 253 | directory is suitable for use with temporary files. A directory is\n\ |
| 254 | considered good for a particular user if it's readable and writable only\n\ |
| 255 | by that user, and if all its parents are modifiable only by the user or\n\ |
| 256 | root.\n\ |
| 257 | \n\ |
| 258 | Options supported:\n\ |
| 259 | \n\ |
| 260 | -h, --help Display this help text.\n\ |
| 261 | -V, --version Display the program's version number.\n\ |
| 262 | -u, --usage Display a terse usage summary.\n\ |
| 263 | \n\ |
| 264 | -b, --bourne Output a `TMPDIR' setting for Bourne shell users.\n\ |
| 265 | -c, --cshell Output a `TMPDIR' setting for C shell users.\n\ |
| 266 | -v, --verbose Report problems to standard error.\n\ |
| 267 | -g, --group NAME Trust group NAME to be honest and true.\n\ |
| 268 | -C, --check PATH Check whether PATH is good, setting exit status.\n\ |
| 269 | \n\ |
| 270 | The default action is to examine the caller's shell and output a suitable\n\ |
| 271 | setting for that shell type.\n\ |
| 272 | ", |
| 273 | fp); |
| 274 | } |
| 275 | |
| 276 | /* --- @main@ --- * |
| 277 | * |
| 278 | * Arguments: @int argc@ = number of command line arguments |
| 279 | * @char *argv[]@ = the actual argument strings |
| 280 | * |
| 281 | * Returns: Zero if all went well, else nonzero. |
| 282 | * |
| 283 | * Use: Performs helpful operations on temporary directories. |
| 284 | */ |
| 285 | |
| 286 | int main(int argc, char *argv[]) |
| 287 | { |
| 288 | int shell = 0; |
| 289 | int duff = 0; |
| 290 | char *p; |
| 291 | |
| 292 | enum { |
| 293 | sh_unknown, |
| 294 | sh_bourne, |
| 295 | sh_csh |
| 296 | }; |
| 297 | |
| 298 | /* --- Initialize variables --- */ |
| 299 | |
| 300 | ego(argv[0]); |
| 301 | me = cp.cp_uid = geteuid(); |
| 302 | cp.cp_what = (CP_WRWORLD | CP_WROTHGRP | CP_WROTHUSR | |
| 303 | CP_STICKYOK | CP_REPORT); |
| 304 | cp.cp_verbose = 0; |
| 305 | cp.cp_report = report; |
| 306 | cp.cp_gids = 0; /* ignore group membership */ |
| 307 | pw = getpwuid(me); |
| 308 | if (!pw) |
| 309 | die(1, "you don't exist"); |
| 310 | |
| 311 | /* --- Parse arguments --- */ |
| 312 | |
| 313 | for (;;) { |
| 314 | static struct option opts[] = { |
| 315 | { "help", 0, 0, 'h' }, |
| 316 | { "version", 0, 0, 'V' }, |
| 317 | { "usage", 0, 0, 'u' }, |
| 318 | { "bourne", 0, 0, 'b' }, |
| 319 | { "cshell", 0, 0, 'c' }, |
| 320 | { "check", OPTF_ARGREQ, 0, 'C' }, |
| 321 | { "verify", OPTF_ARGREQ, 0, 'C' }, |
| 322 | { "verbose", 0, 0, 'v' }, |
| 323 | { "trust-groups", 0, 0, 't' }, |
| 324 | { "group", OPTF_ARGREQ, 0, 'g' }, |
| 325 | { 0, 0, 0, 0 } |
| 326 | }; |
| 327 | int i = mdwopt(argc, argv, "hVu" "bcvtg:c:", opts, 0, 0, 0); |
| 328 | |
| 329 | if (i < 0) |
| 330 | break; |
| 331 | switch (i) { |
| 332 | case 'h': |
| 333 | help(stdout); |
| 334 | exit(0); |
| 335 | case 'V': |
| 336 | version(stdout); |
| 337 | exit(0); |
| 338 | case 'u': |
| 339 | usage(stdout); |
| 340 | exit(0); |
| 341 | case 'b': |
| 342 | shell = sh_bourne; |
| 343 | break; |
| 344 | case 'c': |
| 345 | shell = sh_csh; |
| 346 | break; |
| 347 | case 'C': |
| 348 | return (!fullcheck(optarg)); |
| 349 | break; |
| 350 | case 'g': |
| 351 | allowgroup(&cp, optarg); |
| 352 | break; |
| 353 | case 'v': |
| 354 | cp.cp_verbose++; |
| 355 | break; |
| 356 | default: |
| 357 | duff = 1; |
| 358 | break; |
| 359 | } |
| 360 | } |
| 361 | |
| 362 | if (duff || optind != argc) { |
| 363 | usage(stderr); |
| 364 | exit(1); |
| 365 | } |
| 366 | |
| 367 | /* --- Choose a shell --- */ |
| 368 | |
| 369 | if (!shell) { |
| 370 | if (!(p = getenv("SHELL"))) |
| 371 | p = pw->pw_shell; |
| 372 | if (strstr(p, "csh")) |
| 373 | shell = sh_csh; |
| 374 | else |
| 375 | shell = sh_bourne; |
| 376 | } |
| 377 | |
| 378 | /* --- Start the checking --- */ |
| 379 | |
| 380 | if ((p = goodtmp()) == 0) |
| 381 | die(1, "no good tmp directory"); |
| 382 | switch (shell) { |
| 383 | case sh_bourne: |
| 384 | printf("TMPDIR=\"%s\"; export TMPDIR\n", p); |
| 385 | break; |
| 386 | case sh_csh: |
| 387 | printf("setenv TMPDIR \"%s\"\n", p); |
| 388 | break; |
| 389 | } |
| 390 | |
| 391 | return (0); |
| 392 | } |
| 393 | |
| 394 | /*----- That's all, folks -------------------------------------------------*/ |