| 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 | |
| 52 | /*----- Static variables --------------------------------------------------*/ |
| 53 | |
| 54 | static uid_t me; |
| 55 | static struct checkpath cp; |
| 56 | static struct passwd *pw; |
| 57 | |
| 58 | /*----- Main code ---------------------------------------------------------*/ |
| 59 | |
| 60 | /* --- @ok@ --- * |
| 61 | * |
| 62 | * Arguments: @const char *p@ = pathname to check |
| 63 | * @int *f@ = try-to-create flag |
| 64 | * |
| 65 | * Returns: Nonzero if the directory is OK |
| 66 | * |
| 67 | * Use: Ensures that a directory is OK. If @f@ is a real pointer, |
| 68 | * and @*f@ is set, then try to create the directory. |
| 69 | */ |
| 70 | |
| 71 | static int ok(const char *p, int *f) |
| 72 | { |
| 73 | struct stat st; |
| 74 | |
| 75 | /* --- Read the directory status --- */ |
| 76 | |
| 77 | if (lstat(p, &st)) { |
| 78 | |
| 79 | /* --- Maybe create it if it doesn't exist --- */ |
| 80 | |
| 81 | if (errno != ENOENT || !f || !*f) |
| 82 | return (0); |
| 83 | if (mkdir(p, 0700)) { |
| 84 | *f = 0; |
| 85 | return (0); |
| 86 | } |
| 87 | |
| 88 | /* --- Now read the new status --- * |
| 89 | * |
| 90 | * This fixes a race condition between the previous @lstat@ call and |
| 91 | * the @mkdir@. |
| 92 | */ |
| 93 | |
| 94 | if (lstat(p, &st)) |
| 95 | return (0); |
| 96 | } |
| 97 | |
| 98 | /* --- Make sure the directory is good --- * |
| 99 | * |
| 100 | * It must be a genuine directory (not a link); it must be readable |
| 101 | * and writable only by its owner, and that owner must be me. |
| 102 | */ |
| 103 | |
| 104 | if (S_ISDIR(st.st_mode) && (st.st_mode & 0777) == 0700 && st.st_uid == me) |
| 105 | return (1); |
| 106 | return (0); |
| 107 | } |
| 108 | |
| 109 | /* --- @trytmp@ --- * |
| 110 | * |
| 111 | * Arguments: @const char *parent@ = parent directory name |
| 112 | * @const char *base@ = subdirectory base name |
| 113 | * |
| 114 | * Returns: Pointer to directory name, or null. (String needs freeing.) |
| 115 | * |
| 116 | * Use: Tries to find or create an appropriate temporary directory. |
| 117 | */ |
| 118 | |
| 119 | static char *trytmp(const char *parent, const char *base) |
| 120 | { |
| 121 | static char c[] = { "0123456789" |
| 122 | "abcdefghijklmnopqrstuvwxyz" |
| 123 | "ABCDEFGHIJKLMNOPQRSTUVWXYZ" }; |
| 124 | char *p, *q; |
| 125 | char *qq; |
| 126 | dstr d = DSTR_INIT; |
| 127 | int createflag = 1; |
| 128 | |
| 129 | /* --- Make sure the parent directory is sane --- * |
| 130 | * |
| 131 | * Must make sure that all the lead-up to the temporary directory is safe. |
| 132 | * Otherwise other people can play with symlinks or rename directories |
| 133 | * after I've done all this careful work to make the endpoint directory |
| 134 | * safe. |
| 135 | */ |
| 136 | |
| 137 | if (checkpath(parent, &cp)) |
| 138 | return (0); |
| 139 | |
| 140 | /* --- See whether the trivial version will work --- */ |
| 141 | |
| 142 | dstr_putf(&d, "%s/%s", parent, base); |
| 143 | if (ok(d.buf, &createflag)) |
| 144 | goto good; |
| 145 | |
| 146 | /* --- Now try with various suffixes --- */ |
| 147 | |
| 148 | DENSURE(&d, 4); |
| 149 | qq = d.buf + d.len; |
| 150 | *qq++ = '-'; |
| 151 | |
| 152 | for (p = c; *p; p++) { |
| 153 | qq[0] = *p; |
| 154 | qq[1] = 0; |
| 155 | if (ok(d.buf, &createflag)) |
| 156 | goto good; |
| 157 | for (q = c; *q; q++) { |
| 158 | qq[1] = *q; |
| 159 | qq[2] = 0; |
| 160 | if (ok(d.buf, &createflag)) |
| 161 | goto good; |
| 162 | } |
| 163 | } |
| 164 | |
| 165 | /* --- No joy --- */ |
| 166 | |
| 167 | dstr_destroy(&d); |
| 168 | return (0); |
| 169 | |
| 170 | good: |
| 171 | p = xstrdup(d.buf); |
| 172 | dstr_destroy(&d); |
| 173 | return (p); |
| 174 | } |
| 175 | |
| 176 | /* --- @fullcheck@ --- * |
| 177 | * |
| 178 | * Arguments: @const char *p@ = pointer to path to check |
| 179 | * |
| 180 | * Returns: Zero if it's a bad directory. |
| 181 | * |
| 182 | * Use: Runs a thorough check on a directory. |
| 183 | */ |
| 184 | |
| 185 | static int fullcheck(const char *p) |
| 186 | { return (checkpath(p, &cp) == 0 && ok(p, 0)); } |
| 187 | |
| 188 | /* --- @goodtmp@ --- * |
| 189 | * |
| 190 | * Arguments: --- |
| 191 | * |
| 192 | * Returns: Pointer to a known-good secure temporary directory, or |
| 193 | * null. |
| 194 | * |
| 195 | * Use: Finds a good place to store temporary files. |
| 196 | */ |
| 197 | |
| 198 | static char *goodtmp(void) |
| 199 | { |
| 200 | char *p, *q; |
| 201 | |
| 202 | /* --- First of all, try the user's current choice --- */ |
| 203 | |
| 204 | if ((p = getenv("TMPDIR")) != 0 && fullcheck(p)) |
| 205 | return (p); |
| 206 | |
| 207 | /* --- Try making a directory in `/tmp' --- */ |
| 208 | |
| 209 | if ((q = trytmp("/tmp", pw->pw_name)) != 0) |
| 210 | return (q); |
| 211 | |
| 212 | /* --- That failed: try a directory in the user's home --- */ |
| 213 | |
| 214 | if ((q = trytmp(pw->pw_dir, "tmp")) != 0) |
| 215 | return (q); |
| 216 | |
| 217 | /* --- Still no joy: give up --- * |
| 218 | * |
| 219 | * To be fair, if the user can't find a safe place in his own home |
| 220 | * directory then he's pretty stuffed. |
| 221 | */ |
| 222 | |
| 223 | return (0); |
| 224 | } |
| 225 | |
| 226 | /* --- @report@ --- */ |
| 227 | |
| 228 | static void report(unsigned what, int verbose, |
| 229 | const char *p, const char *msg, |
| 230 | void *arg) |
| 231 | { moan("%s", msg); } |
| 232 | |
| 233 | /* --- @usage@ --- */ |
| 234 | |
| 235 | static void usage(FILE *fp) |
| 236 | { fprintf(fp, "Usage: %s [-bc] [-v PATH]\n", QUIS); } |
| 237 | |
| 238 | /* --- @version@ --- */ |
| 239 | |
| 240 | static void version(FILE *fp) |
| 241 | { fprintf(fp, "%s version %s\n", QUIS, VERSION); } |
| 242 | |
| 243 | /* --- @help@ --- */ |
| 244 | |
| 245 | static void help(FILE *fp) |
| 246 | { |
| 247 | version(fp); |
| 248 | putc('\n', fp); |
| 249 | usage(fp); |
| 250 | fputs("\n\ |
| 251 | Sets a suitable and secure temporary directory, or checks that a given\n\ |
| 252 | directory is suitable for use with temporary files. A directory is\n\ |
| 253 | considered good for a particular user if it's readable and writable only\n\ |
| 254 | by that user, and if all its parents are modifiable only by the user or\n\ |
| 255 | root.\n\ |
| 256 | \n\ |
| 257 | Options supported:\n\ |
| 258 | \n\ |
| 259 | -h, --help Display this help text.\n\ |
| 260 | -V, --version Display the program's version number.\n\ |
| 261 | -u, --usage Display a terse usage summary.\n\ |
| 262 | \n\ |
| 263 | -b, --bourne Output a `TMPDIR' setting for Bourne shell users.\n\ |
| 264 | -c, --cshell Output a `TMPDIR' setting for C shell users.\n\ |
| 265 | -v, --verbose Report problems to standard error.\n\ |
| 266 | -g, --group NAME Trust group NAME to be honest and true.\n\ |
| 267 | -C, --check PATH Check whether PATH is good, setting exit status.\n\ |
| 268 | \n\ |
| 269 | The default action is to examine the caller's shell and output a suitable\n\ |
| 270 | setting for that shell type.\n\ |
| 271 | ", |
| 272 | fp); |
| 273 | } |
| 274 | |
| 275 | /* --- @allowgroup@ --- * |
| 276 | * |
| 277 | * Arguments: @const char *gname@ = trust group @gname@ |
| 278 | * |
| 279 | * Returns: --- |
| 280 | * |
| 281 | * Use: Adds the gid corresponding to @gname@ (which may be a number) |
| 282 | * to the list of things we trust. |
| 283 | */ |
| 284 | |
| 285 | static void allowgroup(const char *gname) |
| 286 | { |
| 287 | struct group *gr; |
| 288 | const char *p; |
| 289 | gid_t g; |
| 290 | |
| 291 | /* --- Check for numeric group spec --- */ |
| 292 | |
| 293 | for (p = gname; *p; p++) { |
| 294 | if (!isdigit((unsigned char)*p)) |
| 295 | goto lookup; |
| 296 | } |
| 297 | g = atoi(gname); |
| 298 | goto insert; |
| 299 | |
| 300 | /* --- Look up a group by name --- */ |
| 301 | |
| 302 | lookup: |
| 303 | if ((gr = getgrnam(gname)) == 0) |
| 304 | die(1, "group %s not found", gname); |
| 305 | g = gr->gr_gid; |
| 306 | |
| 307 | /* --- Insert the group into the table --- */ |
| 308 | |
| 309 | insert: |
| 310 | if (cp.cp_gids >= N(cp.cp_gid)) |
| 311 | die(1, "too many groups"); |
| 312 | cp.cp_gid[cp.cp_gids++] = g; |
| 313 | } |
| 314 | |
| 315 | /* --- @main@ --- * |
| 316 | * |
| 317 | * Arguments: @int argc@ = number of command line arguments |
| 318 | * @char *argv[]@ = the actual argument strings |
| 319 | * |
| 320 | * Returns: Zero if all went well, else nonzero. |
| 321 | * |
| 322 | * Use: Performs helpful operations on temporary directories. |
| 323 | */ |
| 324 | |
| 325 | int main(int argc, char *argv[]) |
| 326 | { |
| 327 | int shell = 0; |
| 328 | int duff = 0; |
| 329 | char *p; |
| 330 | |
| 331 | enum { |
| 332 | sh_unknown, |
| 333 | sh_bourne, |
| 334 | sh_csh |
| 335 | }; |
| 336 | |
| 337 | /* --- Initialize variables --- */ |
| 338 | |
| 339 | ego(argv[0]); |
| 340 | me = geteuid(); |
| 341 | cp.cp_what = (CP_WRWORLD | CP_WROTHGRP | CP_WROTHUSR | |
| 342 | CP_STICKYOK | CP_REPORT); |
| 343 | cp.cp_verbose = 0; |
| 344 | cp.cp_report = report; |
| 345 | checkpath_setids(&cp); |
| 346 | cp.cp_gids = 0; /* ignore group membership */ |
| 347 | pw = getpwuid(me); |
| 348 | if (!pw) |
| 349 | die(1, "you don't exist"); |
| 350 | |
| 351 | /* --- Parse arguments --- */ |
| 352 | |
| 353 | for (;;) { |
| 354 | static struct option opts[] = { |
| 355 | { "help", 0, 0, 'h' }, |
| 356 | { "version", 0, 0, 'V' }, |
| 357 | { "usage", 0, 0, 'u' }, |
| 358 | { "bourne", 0, 0, 'b' }, |
| 359 | { "cshell", 0, 0, 'c' }, |
| 360 | { "check", OPTF_ARGREQ, 0, 'C' }, |
| 361 | { "verify", OPTF_ARGREQ, 0, 'C' }, |
| 362 | { "verbose", 0, 0, 'v' }, |
| 363 | { "trust-groups", 0, 0, 't' }, |
| 364 | { "group", OPTF_ARGREQ, 0, 'g' }, |
| 365 | { 0, 0, 0, 0 } |
| 366 | }; |
| 367 | int i = mdwopt(argc, argv, "hVu" "bcvtg:c:", opts, 0, 0, 0); |
| 368 | |
| 369 | if (i < 0) |
| 370 | break; |
| 371 | switch (i) { |
| 372 | case 'h': |
| 373 | help(stdout); |
| 374 | exit(0); |
| 375 | case 'V': |
| 376 | version(stdout); |
| 377 | exit(0); |
| 378 | case 'u': |
| 379 | usage(stdout); |
| 380 | exit(0); |
| 381 | case 'b': |
| 382 | shell = sh_bourne; |
| 383 | break; |
| 384 | case 'c': |
| 385 | shell = sh_csh; |
| 386 | break; |
| 387 | case 'C': |
| 388 | return (!fullcheck(optarg)); |
| 389 | break; |
| 390 | case 'g': |
| 391 | allowgroup(optarg); |
| 392 | break; |
| 393 | case 'v': |
| 394 | cp.cp_verbose++; |
| 395 | break; |
| 396 | default: |
| 397 | duff = 1; |
| 398 | break; |
| 399 | } |
| 400 | } |
| 401 | |
| 402 | if (duff || optind != argc) { |
| 403 | usage(stderr); |
| 404 | exit(1); |
| 405 | } |
| 406 | |
| 407 | /* --- Choose a shell --- */ |
| 408 | |
| 409 | if (!shell) { |
| 410 | if (!(p = getenv("SHELL"))) |
| 411 | p = pw->pw_shell; |
| 412 | if (strstr(p, "csh")) |
| 413 | shell = sh_csh; |
| 414 | else |
| 415 | shell = sh_bourne; |
| 416 | } |
| 417 | |
| 418 | /* --- Start the checking --- */ |
| 419 | |
| 420 | if ((p = goodtmp()) == 0) |
| 421 | die(1, "no good tmp directory"); |
| 422 | switch (shell) { |
| 423 | case sh_bourne: |
| 424 | printf("TMPDIR=\"%s\"; export TMPDIR\n", p); |
| 425 | break; |
| 426 | case sh_csh: |
| 427 | printf("setenv TMPDIR \"%s\"\n", p); |
| 428 | break; |
| 429 | } |
| 430 | |
| 431 | return (0); |
| 432 | } |
| 433 | |
| 434 | /*----- That's all, folks -------------------------------------------------*/ |