source3/lib/util_sec.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Copyright (C) Jeremy Allison 1998.
   4    rewritten for version 2.0.6 by Tridge
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software
  18    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19 */
  20
  21 #ifndef AUTOCONF_TEST
  22 #include "includes.h"
  23 #else
  24 /* we are running this code in autoconf test mode to see which type of setuid
  25    function works */
  26 #if defined(HAVE_UNISTD_H)
  27 #include <unistd.h>
  28 #endif
  29 #include <stdlib.h>
  30 #include <stdio.h>
  31 #include <sys/types.h>
  32 #include <errno.h>
  33
  34 #ifdef HAVE_SYS_PRIV_H
  35 #include <sys/priv.h>
  36 #endif
  37 #ifdef HAVE_SYS_ID_H
  38 #include <sys/id.h>
  39 #endif
  40
  41 #define DEBUG(x, y) printf y
  42 #define smb_panic(x) exit(1)
  43 #define BOOL int
  44 #endif
  45
  46 /* are we running as non-root? This is used by the regresison test code,
  47    and potentially also for sites that want non-root smbd */
  48 static uid_t initial_uid;
  49 static gid_t initial_gid;
  50
  51 /****************************************************************************
  52 remember what uid we got started as - this allows us to run correctly
  53 as non-root while catching trapdoor systems
  54 ****************************************************************************/
  55 void sec_init(void)
  56 {
  57         initial_uid = geteuid();
  58         initial_gid = getegid();
  59 }
  60
  61 /****************************************************************************
  62 some code (eg. winbindd) needs to know what uid we started as
  63 ****************************************************************************/
  64 uid_t sec_initial_uid(void)
  65 {
  66         return initial_uid;
  67 }
  68
  69 /****************************************************************************
  70 some code (eg. winbindd, profiling shm) needs to know what gid we started as
  71 ****************************************************************************/
  72 gid_t sec_initial_gid(void)
  73 {
  74         return initial_gid;
  75 }
  76
  77 /****************************************************************************
  78 are we running in non-root mode?
  79 ****************************************************************************/
  80 BOOL non_root_mode(void)
  81 {
  82         return (initial_uid != (uid_t)0);
  83 }
  84
  85 /****************************************************************************
  86 abort if we haven't set the uid correctly
  87 ****************************************************************************/
  88 static void assert_uid(uid_t ruid, uid_t euid)
  89 {
  90         if ((euid != (uid_t)-1 && geteuid() != euid) ||
  91             (ruid != (uid_t)-1 && getuid() != ruid)) {
  92                 if (!non_root_mode()) {
  93                         DEBUG(0,("Failed to set uid privileges to (%d,%d) now set to (%d,%d)\n",
  94                                  (int)ruid, (int)euid,
  95                                  (int)getuid(), (int)geteuid()));
  96                         smb_panic("failed to set uid\n");
  97                         exit(1);
  98                 }
  99         }
 100 }
 101
 102 /****************************************************************************
 103 abort if we haven't set the gid correctly
 104 ****************************************************************************/
 105 static void assert_gid(gid_t rgid, gid_t egid)
 106 {
 107         if ((egid != (gid_t)-1 && getegid() != egid) ||
 108             (rgid != (gid_t)-1 && getgid() != rgid)) {
 109                 if (!non_root_mode()) {
 110                         DEBUG(0,("Failed to set gid privileges to (%d,%d) now set to (%d,%d) uid=(%d,%d)\n",
 111                                  (int)rgid, (int)egid,
 112                                  (int)getgid(), (int)getegid(),
 113                                  (int)getuid(), (int)geteuid()));
 114                         smb_panic("failed to set gid\n");
 115                         exit(1);
 116                 }
 117         }
 118 }
 119
 120 /****************************************************************************
 121  Gain root privilege before doing something.
 122  We want to end up with ruid==euid==0
 123 ****************************************************************************/
 124 void gain_root_privilege(void)
 125 {
 126 #if USE_SETRESUID
 127         setresuid(0,0,0);
 128 #endif
 129
 130 #if USE_SETEUID
 131         seteuid(0);
 132 #endif
 133
 134 #if USE_SETREUID
 135         setreuid(0, 0);
 136 #endif
 137
 138 #if USE_SETUIDX
 139         setuidx(ID_EFFECTIVE, 0);
 140         setuidx(ID_REAL, 0);
 141 #endif
 142
 143         /* this is needed on some systems */
 144         setuid(0);
 145
 146         assert_uid(0, 0);
 147 }
 148
 149
 150 /****************************************************************************
 151  Ensure our real and effective groups are zero.
 152  we want to end up with rgid==egid==0
 153 ****************************************************************************/
 154 void gain_root_group_privilege(void)
 155 {
 156 #if USE_SETRESUID
 157         setresgid(0,0,0);
 158 #endif
 159
 160 #if USE_SETREUID
 161         setregid(0,0);
 162 #endif
 163
 164 #if USE_SETEUID
 165         setegid(0);
 166 #endif
 167
 168 #if USE_SETUIDX
 169         setgidx(ID_EFFECTIVE, 0);
 170         setgidx(ID_REAL, 0);
 171 #endif
 172
 173         setgid(0);
 174
 175         assert_gid(0, 0);
 176 }
 177
 178
 179 /****************************************************************************
 180  Set effective uid, and possibly the real uid too.
 181  We want to end up with either:
 182
 183    ruid==uid and euid==uid
 184
 185  or
 186
 187    ruid==0 and euid==uid
 188
 189  depending on what the local OS will allow us to regain root from.
 190 ****************************************************************************/
 191 void set_effective_uid(uid_t uid)
 192 {
 193 #if USE_SETRESUID
 194         /* Set the effective as well as the real uid. */
 195         setresuid(uid,uid,-1);
 196 #endif
 197
 198 #if USE_SETREUID
 199         setreuid(-1,uid);
 200 #endif
 201
 202 #if USE_SETEUID
 203         seteuid(uid);
 204 #endif
 205
 206 #if USE_SETUIDX
 207         setuidx(ID_EFFECTIVE, uid);
 208 #endif
 209
 210         assert_uid(-1, uid);
 211 }
 212
 213 /****************************************************************************
 214  Set *only* the effective gid.
 215  we want to end up with rgid==0 and egid==gid
 216 ****************************************************************************/
 217 void set_effective_gid(gid_t gid)
 218 {
 219 #if USE_SETRESUID
 220         setresgid(-1,gid,-1);
 221 #endif
 222
 223 #if USE_SETREUID
 224         setregid(-1,gid);
 225 #endif
 226
 227 #if USE_SETEUID
 228         setegid(gid);
 229 #endif
 230
 231 #if USE_SETUIDX
 232         setgidx(ID_EFFECTIVE, gid);
 233 #endif
 234
 235         assert_gid(-1, gid);
 236 }
 237
 238 static uid_t saved_euid, saved_ruid;
 239 static gid_t saved_egid, saved_rgid;
 240
 241 /****************************************************************************
 242  save the real and effective uid for later restoration. Used by the quotas
 243  code
 244 ****************************************************************************/
 245 void save_re_uid(void)
 246 {
 247         saved_ruid = getuid();
 248         saved_euid = geteuid();
 249 }
 250
 251
 252 /****************************************************************************
 253  and restore them!
 254 ****************************************************************************/
 255 void restore_re_uid(void)
 256 {
 257         set_effective_uid(0);
 258
 259 #if USE_SETRESUID
 260         setresuid(saved_ruid, saved_euid, -1);
 261 #elif USE_SETREUID
 262         setreuid(saved_ruid, -1);
 263         setreuid(-1,saved_euid);
 264 #elif USE_SETUIDX
 265         setuidx(ID_REAL, saved_ruid);
 266         setuidx(ID_EFFECTIVE, saved_euid);
 267 #else
 268         set_effective_uid(saved_euid);
 269         if (getuid() != saved_ruid)
 270                 setuid(saved_ruid);
 271         set_effective_uid(saved_euid);
 272 #endif
 273
 274         assert_uid(saved_ruid, saved_euid);
 275 }
 276
 277
 278 /****************************************************************************
 279  save the real and effective gid for later restoration. Used by the
 280  getgroups code
 281 ****************************************************************************/
 282 void save_re_gid(void)
 283 {
 284         saved_rgid = getgid();
 285         saved_egid = getegid();
 286 }
 287
 288 /****************************************************************************
 289  and restore them!
 290 ****************************************************************************/
 291 void restore_re_gid(void)
 292 {
 293 #if USE_SETRESUID
 294         setresgid(saved_rgid, saved_egid, -1);
 295 #elif USE_SETREUID
 296         setregid(saved_rgid, -1);
 297         setregid(-1,saved_egid);
 298 #elif USE_SETUIDX
 299         setgidx(ID_REAL, saved_rgid);
 300         setgidx(ID_EFFECTIVE, saved_egid);
 301 #else
 302         set_effective_gid(saved_egid);
 303         if (getgid() != saved_rgid)
 304                 setgid(saved_rgid);
 305         set_effective_gid(saved_egid);
 306 #endif
 307
 308         assert_gid(saved_rgid, saved_egid);
 309 }
 310
 311
 312 /****************************************************************************
 313  set the real AND effective uid to the current effective uid in a way that
 314  allows root to be regained.
 315  This is only possible on some platforms.
 316 ****************************************************************************/
 317 int set_re_uid(void)
 318 {
 319         uid_t uid = geteuid();
 320
 321 #if USE_SETRESUID
 322         setresuid(geteuid(), -1, -1);
 323 #endif
 324
 325 #if USE_SETREUID
 326         setreuid(0, 0);
 327         setreuid(uid, -1);
 328         setreuid(-1, uid);
 329 #endif
 330
 331 #if USE_SETEUID
 332         /* can't be done */
 333         return -1;
 334 #endif
 335
 336 #if USE_SETUIDX
 337         /* can't be done */
 338         return -1;
 339 #endif
 340
 341         assert_uid(uid, uid);
 342         return 0;
 343 }
 344
 345
 346 /****************************************************************************
 347  Become the specified uid and gid - permanently !
 348  there should be no way back if possible
 349 ****************************************************************************/
 350 void become_user_permanently(uid_t uid, gid_t gid)
 351 {
 352         /*
 353          * First - gain root privilege. We do this to ensure
 354          * we can lose it again.
 355          */
 356
 357         gain_root_privilege();
 358         gain_root_group_privilege();
 359
 360 #if USE_SETRESUID
 361         setresgid(gid,gid,gid);
 362         setgid(gid);
 363         setresuid(uid,uid,uid);
 364         setuid(uid);
 365 #endif
 366
 367 #if USE_SETREUID
 368         setregid(gid,gid);
 369         setgid(gid);
 370         setreuid(uid,uid);
 371         setuid(uid);
 372 #endif
 373
 374 #if USE_SETEUID
 375         setegid(gid);
 376         setgid(gid);
 377         setuid(uid);
 378         seteuid(uid);
 379         setuid(uid);
 380 #endif
 381
 382 #if USE_SETUIDX
 383         setgidx(ID_REAL, gid);
 384         setgidx(ID_EFFECTIVE, gid);
 385         setgid(gid);
 386         setuidx(ID_REAL, uid);
 387         setuidx(ID_EFFECTIVE, uid);
 388         setuid(uid);
 389 #endif
 390
 391         assert_uid(uid, uid);
 392         assert_gid(gid, gid);
 393 }
 394
 395 #ifdef AUTOCONF_TEST
 396
 397 /****************************************************************************
 398 this function just checks that we don't get ENOSYS back
 399 ****************************************************************************/
 400 static int have_syscall(void)
 401 {
 402         errno = 0;
 403
 404 #if USE_SETRESUID
 405         setresuid(-1,-1,-1);
 406 #endif
 407
 408 #if USE_SETREUID
 409         setreuid(-1,-1);
 410 #endif
 411
 412 #if USE_SETEUID
 413         seteuid(-1);
 414 #endif
 415
 416 #if USE_SETUIDX
 417         setuidx(ID_EFFECTIVE, -1);
 418 #endif
 419
 420         if (errno == ENOSYS) return -1;
 421
 422         return 0;
 423 }
 424
 425 main()
 426 {
 427         if (getuid() != 0) {
 428 #if (defined(AIX) && defined(USE_SETREUID))
 429                 /* setreuid is badly broken on AIX 4.1, we avoid it completely */
 430                 fprintf(stderr,"avoiding possibly broken setreuid\n");
 431                 exit(1);
 432 #endif
 433
 434                 /* if not running as root then at least check to see if we get ENOSYS - this
 435                    handles Linux 2.0.x with glibc 2.1 */
 436                 fprintf(stderr,"not running as root: checking for ENOSYS\n");
 437                 exit(have_syscall());
 438         }
 439
 440         gain_root_privilege();
 441         gain_root_group_privilege();
 442         set_effective_gid(1);
 443         set_effective_uid(1);
 444         save_re_uid();
 445         restore_re_uid();
 446         gain_root_privilege();
 447         gain_root_group_privilege();
 448         become_user_permanently(1, 1);
 449         setuid(0);
 450         if (getuid() == 0) {
 451                 fprintf(stderr,"uid not set permanently\n");
 452                 exit(1);
 453         }
 454
 455         printf("OK\n");
 456
 457         exit(0);
 458 }
 459 #endif
 460
 461 /****************************************************************************
 462 Check if we are setuid root.  Used in libsmb and smbpasswd paranoia checks.
 463 ****************************************************************************/
 464 BOOL is_setuid_root(void)
 465 {
 466         return (geteuid() == (uid_t)0) && (getuid() != (uid_t)0);
 467 }