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