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