source3/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 /* what user is current? */
  27 extern struct current_user current_user;
  28
  29 pstring OriginalDir;
  30
  31 /****************************************************************************
  32  Initialise the uid routines.
  33 ****************************************************************************/
  34
  35 void init_uid(void)
  36 {
  37         current_user.uid = geteuid();
  38         current_user.gid = getegid();
  39
  40         if (current_user.gid != 0 && current_user.uid == 0) {
  41                 gain_root_group_privilege();
  42         }
  43
  44         current_user.conn = NULL;
  45         current_user.vuid = UID_FIELD_INVALID;
  46
  47         dos_ChDir(OriginalDir);
  48 }
  49
  50 /****************************************************************************
  51  Become the specified uid.
  52 ****************************************************************************/
  53
  54 static BOOL become_uid(uid_t uid)
  55 {
  56         if (uid == (uid_t)-1 || ((sizeof(uid_t) == 2) && (uid == (uid_t)65535))) {
  57                 static int done;
  58                 if (!done) {
  59                         DEBUG(1,("WARNING: using uid %d is a security risk\n",(int)uid));
  60                         done=1;
  61                 }
  62         }
  63
  64         set_effective_uid(uid);
  65
  66         current_user.uid = uid;
  67
  68 #ifdef WITH_PROFILE
  69         profile_p->uid_changes++;
  70 #endif
  71
  72         return(True);
  73 }
  74
  75
  76 /****************************************************************************
  77  Become the specified gid.
  78 ****************************************************************************/
  79
  80 static BOOL become_gid(gid_t gid)
  81 {
  82         if (gid == (gid_t)-1 || ((sizeof(gid_t) == 2) && (gid == (gid_t)65535))) {
  83                 DEBUG(1,("WARNING: using gid %d is a security risk\n",(int)gid));
  84         }
  85
  86         set_effective_gid(gid);
  87
  88         current_user.gid = gid;
  89
  90         return(True);
  91 }
  92
  93
  94 /****************************************************************************
  95  Become the specified uid and gid.
  96 ****************************************************************************/
  97
  98 static BOOL become_id(uid_t uid,gid_t gid)
  99 {
 100         return(become_gid(gid) && become_uid(uid));
 101 }
 102
 103 /****************************************************************************
 104  Become the guest user.
 105 ****************************************************************************/
 106
 107 BOOL become_guest(void)
 108 {
 109   BOOL ret;
 110   static struct passwd *pass=NULL;
 111
 112   if (!pass)
 113     pass = Get_Pwnam(lp_guestaccount(-1),True);
 114   if (!pass) return(False);
 115
 116 #ifdef AIX
 117   /* MWW: From AIX FAQ patch to WU-ftpd: call initgroups before setting IDs */
 118   initgroups(pass->pw_name, (gid_t)pass->pw_gid);
 119 #endif
 120
 121   ret = become_id(pass->pw_uid,pass->pw_gid);
 122
 123   if (!ret) {
 124     DEBUG(1,("Failed to become guest. Invalid guest account?\n"));
 125   }
 126
 127   current_user.conn = NULL;
 128   current_user.vuid = UID_FIELD_INVALID;
 129
 130   return(ret);
 131 }
 132
 133 /*******************************************************************
 134  Check if a username is OK.
 135 ********************************************************************/
 136
 137 static BOOL check_user_ok(connection_struct *conn, user_struct *vuser,int snum)
 138 {
 139   int i;
 140   for (i=0;i<conn->uid_cache.entries;i++)
 141     if (conn->uid_cache.list[i] == vuser->uid) return(True);
 142
 143   if (!user_ok(vuser->name,snum)) return(False);
 144
 145   i = conn->uid_cache.entries % UID_CACHE_SIZE;
 146   conn->uid_cache.list[i] = vuser->uid;
 147
 148   if (conn->uid_cache.entries < UID_CACHE_SIZE)
 149     conn->uid_cache.entries++;
 150
 151   return(True);
 152 }
 153
 154
 155 /****************************************************************************
 156  Become the user of a connection number.
 157 ****************************************************************************/
 158
 159 BOOL become_user(connection_struct *conn, uint16 vuid)
 160 {
 161         user_struct *vuser = get_valid_user_struct(vuid);
 162         int snum;
 163     gid_t gid;
 164         uid_t uid;
 165         char group_c;
 166
 167         if (!conn) {
 168                 DEBUG(2,("Connection not open\n"));
 169                 return(False);
 170         }
 171
 172         /*
 173          * We need a separate check in security=share mode due to vuid
 174          * always being UID_FIELD_INVALID. If we don't do this then
 175          * in share mode security we are *always* changing uid's between
 176          * SMB's - this hurts performance - Badly.
 177          */
 178
 179         if((lp_security() == SEC_SHARE) && (current_user.conn == conn) &&
 180            (current_user.uid == conn->uid)) {
 181                 DEBUG(4,("Skipping become_user - already user\n"));
 182                 return(True);
 183         } else if ((current_user.conn == conn) &&
 184                    (vuser != 0) && (current_user.vuid == vuid) &&
 185                    (current_user.uid == vuser->uid)) {
 186                 DEBUG(4,("Skipping become_user - already user\n"));
 187                 return(True);
 188         }
 189
 190         unbecome_user();
 191
 192         snum = SNUM(conn);
 193
 194         if((vuser != NULL) && !check_user_ok(conn, vuser, snum))
 195                 return False;
 196
 197         if (conn->force_user ||
 198             lp_security() == SEC_SHARE ||
 199             !(vuser) || (vuser->guest)) {
 200                 uid = conn->uid;
 201                 gid = conn->gid;
 202                 current_user.groups = conn->groups;
 203                 current_user.ngroups = conn->ngroups;
 204         } else {
 205                 if (!vuser) {
 206                         DEBUG(2,("Invalid vuid used %d\n",vuid));
 207                         return(False);
 208                 }
 209                 uid = vuser->uid;
 210                 gid = vuser->gid;
 211                 current_user.ngroups = vuser->n_groups;
 212                 current_user.groups  = vuser->groups;
 213         }
 214
 215         /*
 216          * See if we should force group for this service.
 217          * If so this overrides any group set in the force
 218          * user code.
 219          */
 220
 221         if((group_c = *lp_force_group(snum))) {
 222                 if(group_c == '+') {
 223
 224                         /*
 225                          * Only force group if the user is a member of
 226                          * the service group. Check the group memberships for
 227                          * this user (we already have this) to
 228                          * see if we should force the group.
 229                          */
 230
 231                         int i;
 232                         for (i = 0; i < current_user.ngroups; i++) {
 233                                 if (current_user.groups[i] == conn->gid) {
 234                                         gid = conn->gid;
 235                                         break;
 236                                 }
 237                         }
 238                 } else {
 239                         gid = conn->gid;
 240                 }
 241         }
 242
 243         if (!become_gid(gid))
 244                 return(False);
 245
 246 #ifdef HAVE_SETGROUPS
 247         if (!(conn && conn->ipc)) {
 248                 /* groups stuff added by ih/wreu */
 249                 if (current_user.ngroups > 0)
 250                         if (sys_setgroups(current_user.ngroups,
 251                                       current_user.groups)<0) {
 252                                 DEBUG(0,("sys_setgroups call failed!\n"));
 253                         }
 254         }
 255 #endif
 256
 257         if (!conn->admin_user && !become_uid(uid))
 258                 return(False);
 259
 260         current_user.conn = conn;
 261         current_user.vuid = vuid;
 262
 263         DEBUG(5,("become_user uid=(%d,%d) gid=(%d,%d)\n",
 264                  (int)getuid(),(int)geteuid(),(int)getgid(),(int)getegid()));
 265
 266         return(True);
 267 }
 268
 269 /****************************************************************************
 270  Unbecome the user of a connection number.
 271 ****************************************************************************/
 272
 273 BOOL unbecome_user(void )
 274 {
 275         if (!current_user.conn)
 276                 return(False);
 277
 278         dos_ChDir(OriginalDir);
 279
 280         set_effective_uid(0);
 281         set_effective_gid(0);
 282
 283         if (geteuid() != 0) {
 284                 DEBUG(0,("Warning: You appear to have a trapdoor uid system\n"));
 285         }
 286         if (getegid() != 0) {
 287                 DEBUG(0,("Warning: You appear to have a trapdoor gid system\n"));
 288         }
 289
 290         current_user.uid = 0;
 291         current_user.gid = 0;
 292
 293         if (dos_ChDir(OriginalDir) != 0)
 294                 DEBUG( 0, ( "chdir(%s) failed in unbecome_user\n", OriginalDir ) );
 295
 296         DEBUG(5,("unbecome_user now uid=(%d,%d) gid=(%d,%d)\n",
 297                 (int)getuid(),(int)geteuid(),(int)getgid(),(int)getegid()));
 298
 299         current_user.conn = NULL;
 300         current_user.vuid = UID_FIELD_INVALID;
 301
 302         return(True);
 303 }
 304
 305 /****************************************************************************
 306  Become the user of an authenticated connected named pipe.
 307  When this is called we are currently running as the connection
 308  user.
 309 ****************************************************************************/
 310
 311 BOOL become_authenticated_pipe_user(pipes_struct *p)
 312 {
 313         /*
 314          * Go back to root.
 315          */
 316
 317         if(!unbecome_user())
 318                 return False;
 319
 320         /*
 321          * Now become the authenticated user stored in the pipe struct.
 322          */
 323
 324         if(!become_id(p->uid, p->gid)) {
 325                 /* Go back to the connection user. */
 326                 become_user(p->conn, p->vuid);
 327                 return False;
 328         }
 329
 330         return True;
 331 }
 332
 333 /****************************************************************************
 334  Unbecome the user of an authenticated connected named pipe.
 335  When this is called we are running as the authenticated pipe
 336  user and need to go back to being the connection user.
 337 ****************************************************************************/
 338
 339 BOOL unbecome_authenticated_pipe_user(pipes_struct *p)
 340 {
 341         if(!become_id(0,0)) {
 342                 DEBUG(0,("unbecome_authenticated_pipe_user: Unable to go back to root.\n"));
 343                 return False;
 344         }
 345
 346         return become_user(p->conn, p->vuid);
 347 }
 348
 349 static struct current_user current_user_saved;
 350 static int become_root_depth;
 351 static pstring become_root_dir;
 352
 353 /****************************************************************************
 354 This is used when we need to do a privileged operation (such as mucking
 355 with share mode files) and temporarily need root access to do it. This
 356 call should always be paired with an unbecome_root() call immediately
 357 after the operation
 358
 359 Set save_dir if you also need to save/restore the CWD
 360 ****************************************************************************/
 361
 362 void become_root(BOOL save_dir)
 363 {
 364         if (become_root_depth) {
 365                 DEBUG(0,("ERROR: become root depth is non zero\n"));
 366         }
 367         if (save_dir)
 368                 dos_GetWd(become_root_dir);
 369
 370         current_user_saved = current_user;
 371         become_root_depth = 1;
 372
 373         become_uid(0);
 374         become_gid(0);
 375 }
 376
 377 /****************************************************************************
 378 When the privileged operation is over call this
 379
 380 Set save_dir if you also need to save/restore the CWD
 381 ****************************************************************************/
 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 (sys_setgroups(current_user_saved.ngroups,
 406                               current_user_saved.groups)<0)
 407                         DEBUG(0,("ERROR: sys_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                 dos_ChDir(become_root_dir);
 419
 420         current_user = current_user_saved;
 421
 422         become_root_depth = 0;
 423 }