source/smbd/uid.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    uid/user handling
   4    Copyright (C) Andrew Tridgell 1992-1998
   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 #include "includes.h"
  22
  23 /* what user is current? */
  24 extern struct current_user current_user;
  25
  26 /****************************************************************************
  27  Become the guest user without changing the security context stack.
  28 ****************************************************************************/
  29
  30 BOOL change_to_guest(void)
  31 {
  32         static struct passwd *pass=NULL;
  33
  34         if (!pass) {
  35                 /* Don't need to free() this as its stored in a static */
  36                 pass = getpwnam_alloc(lp_guestaccount());
  37                 if (!pass)
  38                         return(False);
  39         }
  40
  41 #ifdef AIX
  42         /* MWW: From AIX FAQ patch to WU-ftpd: call initgroups before
  43            setting IDs */
  44         initgroups(pass->pw_name, pass->pw_gid);
  45 #endif
  46
  47         set_sec_ctx(pass->pw_uid, pass->pw_gid, 0, NULL, NULL);
  48
  49         current_user.conn = NULL;
  50         current_user.vuid = UID_FIELD_INVALID;
  51
  52         passwd_free(&pass);
  53
  54         return True;
  55 }
  56
  57 /*******************************************************************
  58  Check if a username is OK.
  59 ********************************************************************/
  60
  61 static BOOL check_user_ok(connection_struct *conn, user_struct *vuser,int snum)
  62 {
  63         unsigned i;
  64         for (i=0;i<conn->vuid_cache.entries && i< VUID_CACHE_SIZE;i++)
  65                 if (conn->vuid_cache.list[i] == vuser->vuid)
  66                         return(True);
  67
  68         if ((conn->force_user || conn->force_group)
  69             && (conn->vuid != vuser->vuid)) {
  70                 return False;
  71         }
  72
  73         if (!user_ok(vuser->user.unix_name,snum, vuser->groups, vuser->n_groups))
  74                 return(False);
  75
  76         if (!share_access_check(conn, snum, vuser, conn->read_only ? FILE_READ_DATA : FILE_WRITE_DATA)) {
  77                 return False;
  78         }
  79
  80         i = conn->vuid_cache.entries % VUID_CACHE_SIZE;
  81         conn->vuid_cache.list[i] = vuser->vuid;
  82
  83         conn->vuid_cache.entries++;
  84
  85         return(True);
  86 }
  87
  88 /****************************************************************************
  89  Become the user of a connection number without changing the security context
  90  stack, but modify the currnet_user entries.
  91 ****************************************************************************/
  92
  93 BOOL change_to_user(connection_struct *conn, uint16 vuid)
  94 {
  95         user_struct *vuser = get_valid_user_struct(vuid);
  96         int snum;
  97         gid_t gid;
  98         uid_t uid;
  99         char group_c;
 100         BOOL must_free_token = False;
 101         NT_USER_TOKEN *token = NULL;
 102
 103         if (!conn) {
 104                 DEBUG(2,("change_to_user: Connection not open\n"));
 105                 return(False);
 106         }
 107
 108         /*
 109          * We need a separate check in security=share mode due to vuid
 110          * always being UID_FIELD_INVALID. If we don't do this then
 111          * in share mode security we are *always* changing uid's between
 112          * SMB's - this hurts performance - Badly.
 113          */
 114
 115         if((lp_security() == SEC_SHARE) && (current_user.conn == conn) &&
 116            (current_user.uid == conn->uid)) {
 117                 DEBUG(4,("change_to_user: Skipping user change - already user\n"));
 118                 return(True);
 119         } else if ((current_user.conn == conn) &&
 120                    (vuser != 0) && (current_user.vuid == vuid) &&
 121                    (current_user.uid == vuser->uid)) {
 122                 DEBUG(4,("change_to_user: Skipping user change - already user\n"));
 123                 return(True);
 124         }
 125
 126         snum = SNUM(conn);
 127
 128         if (conn->force_user) /* security = share sets this too */ {
 129                 uid = conn->uid;
 130                 gid = conn->gid;
 131                 current_user.groups = conn->groups;
 132                 current_user.ngroups = conn->ngroups;
 133                 token = conn->nt_user_token;
 134         } else if ((vuser) && check_user_ok(conn, vuser, snum)) {
 135                 uid = vuser->uid;
 136                 gid = vuser->gid;
 137                 current_user.ngroups = vuser->n_groups;
 138                 current_user.groups  = vuser->groups;
 139                 token = vuser->nt_user_token;
 140         } else {
 141                 DEBUG(2,("change_to_user: Invalid vuid used %d or vuid not permitted access to share.\n",vuid));
 142                 return False;
 143         }
 144
 145         /*
 146          * See if we should force group for this service.
 147          * If so this overrides any group set in the force
 148          * user code.
 149          */
 150
 151         if((group_c = *lp_force_group(snum))) {
 152                 BOOL is_guest = False;
 153
 154                 if(group_c == '+') {
 155
 156                         /*
 157                          * Only force group if the user is a member of
 158                          * the service group. Check the group memberships for
 159                          * this user (we already have this) to
 160                          * see if we should force the group.
 161                          */
 162
 163                         int i;
 164                         for (i = 0; i < current_user.ngroups; i++) {
 165                                 if (current_user.groups[i] == conn->gid) {
 166                                         gid = conn->gid;
 167                                         break;
 168                                 }
 169                         }
 170                 } else {
 171                         gid = conn->gid;
 172                 }
 173
 174                 /*
 175                  * We've changed the group list in the token - we must
 176                  * re-create it.
 177                  */
 178
 179                 if (vuser && vuser->guest)
 180                         is_guest = True;
 181
 182                 token = create_nt_token(uid, gid, current_user.ngroups, current_user.groups, is_guest);
 183                 if (!token) {
 184                         DEBUG(1, ("change_to_user: create_nt_token failed!\n"));
 185                         return False;
 186                 }
 187                 must_free_token = True;
 188         }
 189
 190         set_sec_ctx(uid, gid, current_user.ngroups, current_user.groups, token);
 191
 192         /*
 193          * Free the new token (as set_sec_ctx copies it).
 194          */
 195
 196         if (must_free_token)
 197                 delete_nt_token(&token);
 198
 199         current_user.conn = conn;
 200         current_user.vuid = vuid;
 201
 202         DEBUG(5,("change_to_user uid=(%d,%d) gid=(%d,%d)\n",
 203                  (int)getuid(),(int)geteuid(),(int)getgid(),(int)getegid()));
 204
 205         return(True);
 206 }
 207
 208 /****************************************************************************
 209  Go back to being root without changing the security context stack,
 210  but modify the current_user entries.
 211 ****************************************************************************/
 212
 213 BOOL change_to_root_user(void)
 214 {
 215         set_root_sec_ctx();
 216
 217         DEBUG(5,("change_to_root_user: now uid=(%d,%d) gid=(%d,%d)\n",
 218                 (int)getuid(),(int)geteuid(),(int)getgid(),(int)getegid()));
 219
 220         current_user.conn = NULL;
 221         current_user.vuid = UID_FIELD_INVALID;
 222
 223         return(True);
 224 }
 225
 226 /****************************************************************************
 227  Become the user of an authenticated connected named pipe.
 228  When this is called we are currently running as the connection
 229  user. Doesn't modify current_user.
 230 ****************************************************************************/
 231
 232 BOOL become_authenticated_pipe_user(pipes_struct *p)
 233 {
 234         if (!push_sec_ctx())
 235                 return False;
 236
 237         set_sec_ctx(p->pipe_user.uid, p->pipe_user.gid,
 238                     p->pipe_user.ngroups, p->pipe_user.groups, p->pipe_user.nt_user_token);
 239
 240         return True;
 241 }
 242
 243 /****************************************************************************
 244  Unbecome the user of an authenticated connected named pipe.
 245  When this is called we are running as the authenticated pipe
 246  user and need to go back to being the connection user. Doesn't modify
 247  current_user.
 248 ****************************************************************************/
 249
 250 BOOL unbecome_authenticated_pipe_user(void)
 251 {
 252         return pop_sec_ctx();
 253 }
 254
 255 /****************************************************************************
 256  Utility functions used by become_xxx/unbecome_xxx.
 257 ****************************************************************************/
 258
 259 struct conn_ctx {
 260         connection_struct *conn;
 261         uint16 vuid;
 262 };
 263
 264 /* A stack of current_user connection contexts. */
 265
 266 static struct conn_ctx conn_ctx_stack[MAX_SEC_CTX_DEPTH];
 267 static int conn_ctx_stack_ndx;
 268
 269 static void push_conn_ctx(void)
 270 {
 271         struct conn_ctx *ctx_p;
 272
 273         /* Check we don't overflow our stack */
 274
 275         if (conn_ctx_stack_ndx == MAX_SEC_CTX_DEPTH) {
 276                 DEBUG(0, ("Connection context stack overflow!\n"));
 277                 smb_panic("Connection context stack overflow!\n");
 278         }
 279
 280         /* Store previous user context */
 281         ctx_p = &conn_ctx_stack[conn_ctx_stack_ndx];
 282
 283         ctx_p->conn = current_user.conn;
 284         ctx_p->vuid = current_user.vuid;
 285
 286         DEBUG(3, ("push_conn_ctx(%u) : conn_ctx_stack_ndx = %d\n",
 287                 (unsigned int)ctx_p->vuid, conn_ctx_stack_ndx ));
 288
 289         conn_ctx_stack_ndx++;
 290 }
 291
 292 static void pop_conn_ctx(void)
 293 {
 294         struct conn_ctx *ctx_p;
 295
 296         /* Check for stack underflow. */
 297
 298         if (conn_ctx_stack_ndx == 0) {
 299                 DEBUG(0, ("Connection context stack underflow!\n"));
 300                 smb_panic("Connection context stack underflow!\n");
 301         }
 302
 303         conn_ctx_stack_ndx--;
 304         ctx_p = &conn_ctx_stack[conn_ctx_stack_ndx];
 305
 306         current_user.conn = ctx_p->conn;
 307         current_user.vuid = ctx_p->vuid;
 308
 309         ctx_p->conn = NULL;
 310         ctx_p->vuid = UID_FIELD_INVALID;
 311 }
 312
 313 /****************************************************************************
 314  Temporarily become a root user.  Must match with unbecome_root(). Saves and
 315  restores the connection context.
 316 ****************************************************************************/
 317
 318 void become_root(void)
 319 {
 320         push_sec_ctx();
 321         push_conn_ctx();
 322         set_root_sec_ctx();
 323 }
 324
 325 /* Unbecome the root user */
 326
 327 void unbecome_root(void)
 328 {
 329         pop_sec_ctx();
 330         pop_conn_ctx();
 331 }
 332
 333 /****************************************************************************
 334  Push the current security context then force a change via change_to_user().
 335  Saves and restores the connection context.
 336 ****************************************************************************/
 337
 338 BOOL become_user(connection_struct *conn, uint16 vuid)
 339 {
 340         if (!push_sec_ctx())
 341                 return False;
 342
 343         push_conn_ctx();
 344
 345         if (!change_to_user(conn, vuid)) {
 346                 pop_sec_ctx();
 347                 pop_conn_ctx();
 348                 return False;
 349         }
 350
 351         return True;
 352 }
 353
 354 BOOL unbecome_user(void)
 355 {
 356         pop_sec_ctx();
 357         pop_conn_ctx();
 358         return True;
 359 }
 360