source/smbd/uid.c

   1 /*
   2    Unix SMB/Netbios implementation.
   3    Version 1.9.
   4    uid/user handling
   5    Copyright (C) Andrew Tridgell 1992-1998
   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 #include "includes.h"
  23
  24 extern int DEBUGLEVEL;
  25
  26 static uid_t initial_uid;
  27 static gid_t initial_gid;
  28
  29 /* what user is current? */
  30 extern struct current_user current_user;
  31
  32 pstring OriginalDir;
  33
  34 /****************************************************************************
  35 initialise the uid routines
  36 ****************************************************************************/
  37 void init_uid(void)
  38 {
  39         initial_uid = current_user.uid = geteuid();
  40         initial_gid = current_user.gid = getegid();
  41
  42         if (initial_gid != 0 && initial_uid == 0) {
  43 #ifdef HAVE_SETRESUID
  44                 setresgid(0,0,0);
  45 #else
  46                 setgid(0);
  47                 setegid(0);
  48 #endif
  49         }
  50
  51         initial_uid = geteuid();
  52         initial_gid = getegid();
  53
  54         current_user.conn = NULL;
  55         current_user.vuid = UID_FIELD_INVALID;
  56
  57         ChDir(OriginalDir);
  58 }
  59
  60
  61 /****************************************************************************
  62   become the specified uid
  63 ****************************************************************************/
  64 static BOOL become_uid(uid_t uid)
  65 {
  66         if (initial_uid != 0) {
  67                 return(True);
  68         }
  69
  70         if (uid == (uid_t)-1 || ((sizeof(uid_t) == 2) && (uid == (uid_t)65535))) {
  71                 static int done;
  72                 if (!done) {
  73                         DEBUG(1,("WARNING: using uid %d is a security risk\n",(int)uid));
  74                         done=1;
  75                 }
  76         }
  77
  78 #ifdef HAVE_TRAPDOOR_UID
  79 #ifdef HAVE_SETUIDX
  80         /* AIX3 has setuidx which is NOT a trapoor function (tridge) */
  81         if (setuidx(ID_EFFECTIVE, uid) != 0) {
  82                 if (seteuid(uid) != 0) {
  83                         DEBUG(1,("Can't set uid %d (setuidx)\n", (int)uid));
  84                         return False;
  85                 }
  86         }
  87 #endif
  88 #endif
  89
  90 #ifdef HAVE_SETRESUID
  91     if (setresuid(-1,uid,-1) != 0)
  92 #else
  93     if ((seteuid(uid) != 0) &&
  94         (setuid(uid) != 0))
  95 #endif
  96       {
  97         DEBUG(0,("Couldn't set uid %d currently set to (%d,%d)\n",
  98                  (int)uid,(int)getuid(), (int)geteuid()));
  99         if (uid > (uid_t)32000) {
 100                 DEBUG(0,("Looks like your OS doesn't like high uid values - try using a different account\n"));
 101         }
 102         return(False);
 103       }
 104
 105     if (((uid == (uid_t)-1) || ((sizeof(uid_t) == 2) && (uid == 65535))) && (geteuid() != uid)) {
 106             DEBUG(0,("Invalid uid -1. perhaps you have a account with uid 65535?\n"));
 107             return(False);
 108     }
 109
 110     current_user.uid = uid;
 111
 112     return(True);
 113 }
 114
 115
 116 /****************************************************************************
 117   become the specified gid
 118 ****************************************************************************/
 119 static BOOL become_gid(gid_t gid)
 120 {
 121   if (initial_uid != 0)
 122     return(True);
 123
 124   if (gid == (gid_t)-1 || ((sizeof(gid_t) == 2) && (gid == (gid_t)65535))) {
 125     DEBUG(1,("WARNING: using gid %d is a security risk\n",(int)gid));
 126   }
 127
 128 #ifdef HAVE_SETRESUID
 129   if (setresgid(-1,gid,-1) != 0)
 130 #else
 131   if (setgid(gid) != 0)
 132 #endif
 133       {
 134         DEBUG(0,("Couldn't set gid %d currently set to (%d,%d)\n",
 135                  (int)gid,(int)getgid(),(int)getegid()));
 136         if (gid > 32000) {
 137                 DEBUG(0,("Looks like your OS doesn't like high gid values - try using a different account\n"));
 138         }
 139         return(False);
 140       }
 141
 142   current_user.gid = gid;
 143
 144   return(True);
 145 }
 146
 147
 148 /****************************************************************************
 149   become the specified uid and gid
 150 ****************************************************************************/
 151 static BOOL become_id(uid_t uid,gid_t gid)
 152 {
 153         return(become_gid(gid) && become_uid(uid));
 154 }
 155
 156 /****************************************************************************
 157 become the guest user
 158 ****************************************************************************/
 159 BOOL become_guest(void)
 160 {
 161   BOOL ret;
 162   static struct passwd *pass=NULL;
 163
 164   if (initial_uid != 0)
 165     return(True);
 166
 167   if (!pass)
 168     pass = Get_Pwnam(lp_guestaccount(-1),True);
 169   if (!pass) return(False);
 170
 171 #ifdef AIX
 172   /* MWW: From AIX FAQ patch to WU-ftpd: call initgroups before setting IDs */
 173   initgroups(pass->pw_name, (gid_t)pass->pw_gid);
 174 #endif
 175
 176   ret = become_id(pass->pw_uid,pass->pw_gid);
 177
 178   if (!ret) {
 179     DEBUG(1,("Failed to become guest. Invalid guest account?\n"));
 180   }
 181
 182   current_user.conn = NULL;
 183   current_user.vuid = UID_FIELD_INVALID;
 184
 185   return(ret);
 186 }
 187
 188 /*******************************************************************
 189 check if a username is OK
 190 ********************************************************************/
 191 static BOOL check_user_ok(connection_struct *conn, user_struct *vuser,int snum)
 192 {
 193   int i;
 194   for (i=0;i<conn->uid_cache.entries;i++)
 195     if (conn->uid_cache.list[i] == vuser->uid) return(True);
 196
 197   if (!user_ok(vuser->name,snum)) return(False);
 198
 199   i = conn->uid_cache.entries % UID_CACHE_SIZE;
 200   conn->uid_cache.list[i] = vuser->uid;
 201
 202   if (conn->uid_cache.entries < UID_CACHE_SIZE)
 203     conn->uid_cache.entries++;
 204
 205   return(True);
 206 }
 207
 208
 209 /****************************************************************************
 210   become the user of a connection number
 211 ****************************************************************************/
 212 BOOL become_user(connection_struct *conn, uint16 vuid)
 213 {
 214         user_struct *vuser = get_valid_user_struct(vuid);
 215         int snum;
 216     gid_t gid;
 217         uid_t uid;
 218
 219         /*
 220          * We need a separate check in security=share mode due to vuid
 221          * always being UID_FIELD_INVALID. If we don't do this then
 222          * in share mode security we are *always* changing uid's between
 223          * SMB's - this hurts performance - Badly.
 224          */
 225
 226         if((lp_security() == SEC_SHARE) && (current_user.conn == conn) &&
 227            (current_user.uid == conn->uid)) {
 228                 DEBUG(4,("Skipping become_user - already user\n"));
 229                 return(True);
 230         } else if ((current_user.conn == conn) &&
 231                    (vuser != 0) && (current_user.vuid == vuid) &&
 232                    (current_user.uid == vuser->uid)) {
 233                 DEBUG(4,("Skipping become_user - already user\n"));
 234                 return(True);
 235         }
 236
 237         unbecome_user();
 238
 239         if (!conn) {
 240                 DEBUG(2,("Connection not open\n"));
 241                 return(False);
 242         }
 243
 244         snum = SNUM(conn);
 245
 246         if((vuser != NULL) && !check_user_ok(conn, vuser, snum))
 247                 return False;
 248
 249         if (conn->force_user ||
 250             lp_security() == SEC_SHARE ||
 251             !(vuser) || (vuser->guest)) {
 252                 uid = conn->uid;
 253                 gid = conn->gid;
 254                 current_user.groups = conn->groups;
 255                 current_user.ngroups = conn->ngroups;
 256         } else {
 257                 if (!vuser) {
 258                         DEBUG(2,("Invalid vuid used %d\n",vuid));
 259                         return(False);
 260                 }
 261                 uid = vuser->uid;
 262                 if(!*lp_force_group(snum)) {
 263                         gid = vuser->gid;
 264                 } else {
 265                         gid = conn->gid;
 266                 }
 267                 current_user.ngroups = vuser->n_groups;
 268                 current_user.groups  = vuser->groups;
 269         }
 270
 271         if (initial_uid == 0)  {
 272                 if (!become_gid(gid)) return(False);
 273
 274 #ifdef HAVE_SETGROUPS
 275                 if (!(conn && conn->ipc)) {
 276                         /* groups stuff added by ih/wreu */
 277                         if (current_user.ngroups > 0)
 278                                 if (setgroups(current_user.ngroups,
 279                                               current_user.groups)<0) {
 280                                         DEBUG(0,("setgroups call failed!\n"));
 281                                 }
 282                 }
 283 #endif
 284
 285                 if (!conn->admin_user && !become_uid(uid))
 286                         return(False);
 287         }
 288
 289         current_user.conn = conn;
 290         current_user.vuid = vuid;
 291
 292         DEBUG(5,("become_user uid=(%d,%d) gid=(%d,%d)\n",
 293                  (int)getuid(),(int)geteuid(),(int)getgid(),(int)getegid()));
 294
 295         return(True);
 296 }
 297
 298 /****************************************************************************
 299   unbecome the user of a connection number
 300 ****************************************************************************/
 301 BOOL unbecome_user(void )
 302 {
 303   if (!current_user.conn)
 304     return(False);
 305
 306   ChDir(OriginalDir);
 307
 308   if (initial_uid == 0)
 309     {
 310 #ifdef HAVE_SETRESUID
 311       setresuid(-1,getuid(),-1);
 312       setresgid(-1,getgid(),-1);
 313 #else
 314       if (seteuid(initial_uid) != 0)
 315         setuid(initial_uid);
 316       setgid(initial_gid);
 317 #endif
 318     }
 319
 320 #ifdef NO_EID
 321   if (initial_uid == 0)
 322     DEBUG(2,("Running with no EID\n"));
 323   initial_uid = getuid();
 324   initial_gid = getgid();
 325 #else
 326   if (geteuid() != initial_uid) {
 327           DEBUG(0,("Warning: You appear to have a trapdoor uid system\n"));
 328           initial_uid = geteuid();
 329   }
 330   if (getegid() != initial_gid) {
 331           DEBUG(0,("Warning: You appear to have a trapdoor gid system\n"));
 332           initial_gid = getegid();
 333   }
 334 #endif
 335
 336   current_user.uid = initial_uid;
 337   current_user.gid = initial_gid;
 338
 339   if (ChDir(OriginalDir) != 0)
 340     DEBUG( 0, ( "chdir(%s) failed in unbecome_user\n", OriginalDir ) );
 341
 342   DEBUG(5,("unbecome_user now uid=(%d,%d) gid=(%d,%d)\n",
 343         (int)getuid(),(int)geteuid(),(int)getgid(),(int)getegid()));
 344
 345   current_user.conn = NULL;
 346   current_user.vuid = UID_FIELD_INVALID;
 347
 348   return(True);
 349 }
 350
 351 static struct current_user current_user_saved;
 352 static int become_root_depth;
 353 static pstring become_root_dir;
 354
 355 /****************************************************************************
 356 This is used when we need to do a privilaged operation (such as mucking
 357 with share mode files) and temporarily need root access to do it. This
 358 call should always be paired with an unbecome_root() call immediately
 359 after the operation
 360
 361 Set save_dir if you also need to save/restore the CWD
 362 ****************************************************************************/
 363 void become_root(BOOL save_dir)
 364 {
 365         if (become_root_depth) {
 366                 DEBUG(0,("ERROR: become root depth is non zero\n"));
 367         }
 368         if (save_dir)
 369                 GetWd(become_root_dir);
 370
 371         current_user_saved = current_user;
 372         become_root_depth = 1;
 373
 374         become_uid(0);
 375         become_gid(0);
 376 }
 377
 378 /****************************************************************************
 379 When the privilaged operation is over call this
 380
 381 Set save_dir if you also need to save/restore the CWD
 382 ****************************************************************************/
 383 void unbecome_root(BOOL restore_dir)
 384 {
 385         if (become_root_depth != 1) {
 386                 DEBUG(0,("ERROR: unbecome root depth is %d\n",
 387                          become_root_depth));
 388         }
 389
 390         /* we might have done a become_user() while running as root,
 391            if we have then become root again in order to become
 392            non root! */
 393         if (current_user.uid != 0) {
 394                 become_uid(0);
 395         }
 396
 397         /* restore our gid first */
 398         if (!become_gid(current_user_saved.gid)) {
 399                 DEBUG(0,("ERROR: Failed to restore gid\n"));
 400                 exit_server("Failed to restore gid");
 401         }
 402
 403 #ifdef HAVE_SETGROUPS
 404         if (current_user_saved.ngroups > 0) {
 405                 if (setgroups(current_user_saved.ngroups,
 406                               current_user_saved.groups)<0)
 407                         DEBUG(0,("ERROR: setgroups call failed!\n"));
 408         }
 409 #endif
 410
 411         /* now restore our uid */
 412         if (!become_uid(current_user_saved.uid)) {
 413                 DEBUG(0,("ERROR: Failed to restore uid\n"));
 414                 exit_server("Failed to restore uid");
 415         }
 416
 417         if (restore_dir)
 418                 ChDir(become_root_dir);
 419
 420         current_user = current_user_saved;
 421
 422         become_root_depth = 0;
 423 }