source/lib/util_sec.c

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