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 *only* the effective uid.
 181  we want to end up with ruid==0 and euid==uid
 182 ****************************************************************************/
 183 void set_effective_uid(uid_t uid)
 184 {
 185 #if USE_SETRESUID
 186         /* On Systems which have this function, would it not be more
 187          * appropriate to also set the real uid by doing
 188          * setresuid(uid,uid,-1)? This would make patching AFS
 189          * unnecessary. See comment in lib/afs.c. */
 190         setresuid(-1,uid,-1);
 191 #endif
 192
 193 #if USE_SETREUID
 194         setreuid(-1,uid);
 195 #endif
 196
 197 #if USE_SETEUID
 198         seteuid(uid);
 199 #endif
 200
 201 #if USE_SETUIDX
 202         setuidx(ID_EFFECTIVE, uid);
 203 #endif
 204
 205         assert_uid(-1, uid);
 206 }
 207
 208 /****************************************************************************
 209  Set *only* the effective gid.
 210  we want to end up with rgid==0 and egid==gid
 211 ****************************************************************************/
 212 void set_effective_gid(gid_t gid)
 213 {
 214 #if USE_SETRESUID
 215         setresgid(-1,gid,-1);
 216 #endif
 217
 218 #if USE_SETREUID
 219         setregid(-1,gid);
 220 #endif
 221
 222 #if USE_SETEUID
 223         setegid(gid);
 224 #endif
 225
 226 #if USE_SETUIDX
 227         setgidx(ID_EFFECTIVE, gid);
 228 #endif
 229
 230         assert_gid(-1, gid);
 231 }
 232
 233 static uid_t saved_euid, saved_ruid;
 234 static gid_t saved_egid, saved_rgid;
 235
 236 /****************************************************************************
 237  save the real and effective uid for later restoration. Used by the quotas
 238  code
 239 ****************************************************************************/
 240 void save_re_uid(void)
 241 {
 242         saved_ruid = getuid();
 243         saved_euid = geteuid();
 244 }
 245
 246
 247 /****************************************************************************
 248  and restore them!
 249 ****************************************************************************/
 250 void restore_re_uid(void)
 251 {
 252         set_effective_uid(0);
 253
 254 #if USE_SETRESUID
 255         setresuid(saved_ruid, saved_euid, -1);
 256 #elif USE_SETREUID
 257         setreuid(saved_ruid, -1);
 258         setreuid(-1,saved_euid);
 259 #elif USE_SETUIDX
 260         setuidx(ID_REAL, saved_ruid);
 261         setuidx(ID_EFFECTIVE, saved_euid);
 262 #else
 263         set_effective_uid(saved_euid);
 264         if (getuid() != saved_ruid)
 265                 setuid(saved_ruid);
 266         set_effective_uid(saved_euid);
 267 #endif
 268
 269         assert_uid(saved_ruid, saved_euid);
 270 }
 271
 272
 273 /****************************************************************************
 274  save the real and effective gid for later restoration. Used by the
 275  getgroups code
 276 ****************************************************************************/
 277 void save_re_gid(void)
 278 {
 279         saved_rgid = getgid();
 280         saved_egid = getegid();
 281 }
 282
 283 /****************************************************************************
 284  and restore them!
 285 ****************************************************************************/
 286 void restore_re_gid(void)
 287 {
 288 #if USE_SETRESUID
 289         setresgid(saved_rgid, saved_egid, -1);
 290 #elif USE_SETREUID
 291         setregid(saved_rgid, -1);
 292         setregid(-1,saved_egid);
 293 #elif USE_SETUIDX
 294         setgidx(ID_REAL, saved_rgid);
 295         setgidx(ID_EFFECTIVE, saved_egid);
 296 #else
 297         set_effective_gid(saved_egid);
 298         if (getgid() != saved_rgid)
 299                 setgid(saved_rgid);
 300         set_effective_gid(saved_egid);
 301 #endif
 302
 303         assert_gid(saved_rgid, saved_egid);
 304 }
 305
 306
 307 /****************************************************************************
 308  set the real AND effective uid to the current effective uid in a way that
 309  allows root to be regained.
 310  This is only possible on some platforms.
 311 ****************************************************************************/
 312 int set_re_uid(void)
 313 {
 314         uid_t uid = geteuid();
 315
 316 #if USE_SETRESUID
 317         setresuid(geteuid(), -1, -1);
 318 #endif
 319
 320 #if USE_SETREUID
 321         setreuid(0, 0);
 322         setreuid(uid, -1);
 323         setreuid(-1, uid);
 324 #endif
 325
 326 #if USE_SETEUID
 327         /* can't be done */
 328         return -1;
 329 #endif
 330
 331 #if USE_SETUIDX
 332         /* can't be done */
 333         return -1;
 334 #endif
 335
 336         assert_uid(uid, uid);
 337         return 0;
 338 }
 339
 340
 341 /****************************************************************************
 342  Become the specified uid and gid - permanently !
 343  there should be no way back if possible
 344 ****************************************************************************/
 345 void become_user_permanently(uid_t uid, gid_t gid)
 346 {
 347         /*
 348          * First - gain root privilege. We do this to ensure
 349          * we can lose it again.
 350          */
 351
 352         gain_root_privilege();
 353         gain_root_group_privilege();
 354
 355 #if USE_SETRESUID
 356         setresgid(gid,gid,gid);
 357         setgid(gid);
 358         setresuid(uid,uid,uid);
 359         setuid(uid);
 360 #endif
 361
 362 #if USE_SETREUID
 363         setregid(gid,gid);
 364         setgid(gid);
 365         setreuid(uid,uid);
 366         setuid(uid);
 367 #endif
 368
 369 #if USE_SETEUID
 370         setegid(gid);
 371         setgid(gid);
 372         setuid(uid);
 373         seteuid(uid);
 374         setuid(uid);
 375 #endif
 376
 377 #if USE_SETUIDX
 378         setgidx(ID_REAL, gid);
 379         setgidx(ID_EFFECTIVE, gid);
 380         setgid(gid);
 381         setuidx(ID_REAL, uid);
 382         setuidx(ID_EFFECTIVE, uid);
 383         setuid(uid);
 384 #endif
 385
 386         assert_uid(uid, uid);
 387         assert_gid(gid, gid);
 388 }
 389
 390 #ifdef AUTOCONF_TEST
 391
 392 /****************************************************************************
 393 this function just checks that we don't get ENOSYS back
 394 ****************************************************************************/
 395 static int have_syscall(void)
 396 {
 397         errno = 0;
 398
 399 #if USE_SETRESUID
 400         setresuid(-1,-1,-1);
 401 #endif
 402
 403 #if USE_SETREUID
 404         setreuid(-1,-1);
 405 #endif
 406
 407 #if USE_SETEUID
 408         seteuid(-1);
 409 #endif
 410
 411 #if USE_SETUIDX
 412         setuidx(ID_EFFECTIVE, -1);
 413 #endif
 414
 415         if (errno == ENOSYS) return -1;
 416
 417         return 0;
 418 }
 419
 420 main()
 421 {
 422         if (getuid() != 0) {
 423 #if (defined(AIX) && defined(USE_SETREUID))
 424                 /* setreuid is badly broken on AIX 4.1, we avoid it completely */
 425                 fprintf(stderr,"avoiding possibly broken setreuid\n");
 426                 exit(1);
 427 #endif
 428
 429                 /* if not running as root then at least check to see if we get ENOSYS - this
 430                    handles Linux 2.0.x with glibc 2.1 */
 431                 fprintf(stderr,"not running as root: checking for ENOSYS\n");
 432                 exit(have_syscall());
 433         }
 434
 435         gain_root_privilege();
 436         gain_root_group_privilege();
 437         set_effective_gid(1);
 438         set_effective_uid(1);
 439         save_re_uid();
 440         restore_re_uid();
 441         gain_root_privilege();
 442         gain_root_group_privilege();
 443         become_user_permanently(1, 1);
 444         setuid(0);
 445         if (getuid() == 0) {
 446                 fprintf(stderr,"uid not set permanently\n");
 447                 exit(1);
 448         }
 449
 450         printf("OK\n");
 451
 452         exit(0);
 453 }
 454 #endif
 455
 456 /****************************************************************************
 457 Check if we are setuid root.  Used in libsmb and smbpasswd paranoia checks.
 458 ****************************************************************************/
 459 BOOL is_setuid_root(void)
 460 {
 461         return (geteuid() == (uid_t)0) && (getuid() != (uid_t)0);
 462 }