source/lib/util_seaccess.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Copyright (C) Luke Kenneth Casson Leighton 1996-2000.
   4    Copyright (C) Tim Potter 2000.
   5    Copyright (C) Re-written by Jeremy Allison 2000.
   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 DOM_SID global_sid_Builtin;
  25
  26 /*********************************************************************************
  27  Check an ACE against a SID.  We return the remaining needed permission
  28  bits not yet granted. Zero means permission allowed (no more needed bits).
  29 **********************************************************************************/
  30
  31 static uint32 check_ace(SEC_ACE *ace, const NT_USER_TOKEN *token, uint32 acc_desired,
  32                         NTSTATUS *status)
  33 {
  34         uint32 mask = ace->info.mask;
  35
  36         /*
  37          * Inherit only is ignored.
  38          */
  39
  40         if (ace->flags & SEC_ACE_FLAG_INHERIT_ONLY) {
  41                 return acc_desired;
  42         }
  43
  44         /*
  45          * If this ACE has no SID in common with the token,
  46          * ignore it as it cannot be used to make an access
  47          * determination.
  48          */
  49
  50         if (!token_sid_in_ace( token, ace))
  51                 return acc_desired;
  52
  53         switch (ace->type) {
  54                 case SEC_ACE_TYPE_ACCESS_ALLOWED:
  55                         /*
  56                          * This is explicitly allowed.
  57                          * Remove the bits from the remaining
  58                          * access required. Return the remaining
  59                          * bits needed.
  60                          */
  61                         acc_desired &= ~mask;
  62                         break;
  63                 case SEC_ACE_TYPE_ACCESS_DENIED:
  64                         /*
  65                          * This is explicitly denied.
  66                          * If any bits match terminate here,
  67                          * we are denied.
  68                          */
  69                         if (acc_desired & mask) {
  70                                 *status = NT_STATUS_ACCESS_DENIED;
  71                                 return 0xFFFFFFFF;
  72                         }
  73                         break;
  74                 case SEC_ACE_TYPE_SYSTEM_ALARM:
  75                 case SEC_ACE_TYPE_SYSTEM_AUDIT:
  76                         *status = NT_STATUS_NOT_IMPLEMENTED;
  77                         return 0xFFFFFFFF;
  78                 default:
  79                         *status = NT_STATUS_INVALID_PARAMETER;
  80                         return 0xFFFFFFFF;
  81         }
  82
  83         return acc_desired;
  84 }
  85
  86 /*********************************************************************************
  87  Maximum access was requested. Calculate the max possible. Fail if it doesn't
  88  include other bits requested.
  89 **********************************************************************************/
  90
  91 static BOOL get_max_access( SEC_ACL *the_acl, const NT_USER_TOKEN *token, uint32 *granted,
  92                             uint32 desired,
  93                             NTSTATUS *status)
  94 {
  95         uint32 acc_denied = 0;
  96         uint32 acc_granted = 0;
  97         size_t i;
  98
  99         for ( i = 0 ; i < the_acl->num_aces; i++) {
 100                 SEC_ACE *ace = &the_acl->ace[i];
 101                 uint32 mask = ace->info.mask;
 102
 103                 if (!token_sid_in_ace( token, ace))
 104                         continue;
 105
 106                 switch (ace->type) {
 107                         case SEC_ACE_TYPE_ACCESS_ALLOWED:
 108                                 acc_granted |= (mask & ~acc_denied);
 109                                 break;
 110                         case SEC_ACE_TYPE_ACCESS_DENIED:
 111                                 acc_denied |= (mask & ~acc_granted);
 112                                 break;
 113                         case SEC_ACE_TYPE_SYSTEM_ALARM:
 114                         case SEC_ACE_TYPE_SYSTEM_AUDIT:
 115                                 *status = NT_STATUS_NOT_IMPLEMENTED;
 116                                 *granted = 0;
 117                                 return False;
 118                         default:
 119                                 *status = NT_STATUS_INVALID_PARAMETER;
 120                                 *granted = 0;
 121                                 return False;
 122                 }
 123         }
 124
 125         /*
 126          * If we were granted no access, or we desired bits that we
 127          * didn't get, then deny.
 128          */
 129
 130         if ((acc_granted == 0) || ((acc_granted & desired) != desired)) {
 131                 *status = NT_STATUS_ACCESS_DENIED;
 132                 *granted = 0;
 133                 return False;
 134         }
 135
 136         /*
 137          * Return the access we did get.
 138          */
 139
 140         *granted = acc_granted;
 141         *status = NT_STATUS_OK;
 142         return True;
 143 }
 144
 145 /* Map generic access rights to object specific rights.  This technique is
 146    used to give meaning to assigning read, write, execute and all access to
 147    objects.  Each type of object has its own mapping of generic to object
 148    specific access rights. */
 149
 150 void se_map_generic(uint32 *access_mask, struct generic_mapping *mapping)
 151 {
 152         uint32 old_mask = *access_mask;
 153
 154         if (*access_mask & GENERIC_READ_ACCESS) {
 155                 *access_mask &= ~GENERIC_READ_ACCESS;
 156                 *access_mask |= mapping->generic_read;
 157         }
 158
 159         if (*access_mask & GENERIC_WRITE_ACCESS) {
 160                 *access_mask &= ~GENERIC_WRITE_ACCESS;
 161                 *access_mask |= mapping->generic_write;
 162         }
 163
 164         if (*access_mask & GENERIC_EXECUTE_ACCESS) {
 165                 *access_mask &= ~GENERIC_EXECUTE_ACCESS;
 166                 *access_mask |= mapping->generic_execute;
 167         }
 168
 169         if (*access_mask & GENERIC_ALL_ACCESS) {
 170                 *access_mask &= ~GENERIC_ALL_ACCESS;
 171                 *access_mask |= mapping->generic_all;
 172         }
 173
 174         if (old_mask != *access_mask) {
 175                 DEBUG(10, ("se_map_generic(): mapped mask 0x%08x to 0x%08x\n",
 176                            old_mask, *access_mask));
 177         }
 178 }
 179
 180 /* Map standard access rights to object specific rights.  This technique is
 181    used to give meaning to assigning read, write, execute and all access to
 182    objects.  Each type of object has its own mapping of standard to object
 183    specific access rights. */
 184
 185 void se_map_standard(uint32 *access_mask, struct standard_mapping *mapping)
 186 {
 187         uint32 old_mask = *access_mask;
 188
 189         if (*access_mask & READ_CONTROL_ACCESS) {
 190                 *access_mask &= ~READ_CONTROL_ACCESS;
 191                 *access_mask |= mapping->std_read;
 192         }
 193
 194         if (*access_mask & (DELETE_ACCESS|WRITE_DAC_ACCESS|WRITE_OWNER_ACCESS|SYNCHRONIZE_ACCESS)) {
 195                 *access_mask &= ~(DELETE_ACCESS|WRITE_DAC_ACCESS|WRITE_OWNER_ACCESS|SYNCHRONIZE_ACCESS);
 196                 *access_mask |= mapping->std_all;
 197         }
 198
 199         if (old_mask != *access_mask) {
 200                 DEBUG(10, ("se_map_standard(): mapped mask 0x%08x to 0x%08x\n",
 201                            old_mask, *access_mask));
 202         }
 203 }
 204
 205 /*****************************************************************************
 206  Check access rights of a user against a security descriptor.  Look at
 207  each ACE in the security descriptor until an access denied ACE denies
 208  any of the desired rights to the user or any of the users groups, or one
 209  or more ACEs explicitly grant all requested access rights.  See
 210  "Access-Checking" document in MSDN.
 211 *****************************************************************************/
 212
 213 BOOL se_access_check(const SEC_DESC *sd, const NT_USER_TOKEN *token,
 214                      uint32 acc_desired, uint32 *acc_granted,
 215                      NTSTATUS *status)
 216 {
 217         extern NT_USER_TOKEN anonymous_token;
 218         size_t i;
 219         SEC_ACL *the_acl;
 220         fstring sid_str;
 221         uint32 tmp_acc_desired = acc_desired;
 222
 223         if (!status || !acc_granted)
 224                 return False;
 225
 226         if (!token)
 227                 token = &anonymous_token;
 228
 229         *status = NT_STATUS_OK;
 230         *acc_granted = 0;
 231
 232         DEBUG(10,("se_access_check: requested access 0x%08x, for NT token with %u entries and first sid %s.\n",
 233                  (unsigned int)acc_desired, (unsigned int)token->num_sids,
 234                 sid_to_string(sid_str, &token->user_sids[0])));
 235
 236         /*
 237          * No security descriptor or security descriptor with no DACL
 238          * present allows all access.
 239          */
 240
 241         /* ACL must have something in it */
 242
 243         if (!sd || (sd && (!(sd->type & SEC_DESC_DACL_PRESENT) || sd->dacl == NULL))) {
 244                 *status = NT_STATUS_OK;
 245                 *acc_granted = acc_desired;
 246                 DEBUG(5, ("se_access_check: no sd or blank DACL, access allowed\n"));
 247                 return True;
 248         }
 249
 250         /* The user sid is the first in the token */
 251         if (DEBUGLVL(3)) {
 252                 DEBUG(3, ("se_access_check: user sid is %s\n", sid_to_string(sid_str, &token->user_sids[PRIMARY_USER_SID_INDEX]) ));
 253
 254                 for (i = 1; i < token->num_sids; i++) {
 255                         DEBUGADD(3, ("se_access_check: also %s\n",
 256                                   sid_to_string(sid_str, &token->user_sids[i])));
 257                 }
 258         }
 259
 260         /* Is the token the owner of the SID ? */
 261
 262         if (sd->owner_sid) {
 263                 for (i = 0; i < token->num_sids; i++) {
 264                         if (sid_equal(&token->user_sids[i], sd->owner_sid)) {
 265                                 /*
 266                                  * The owner always has SEC_RIGHTS_WRITE_DAC & READ_CONTROL.
 267                                  */
 268                                 if (tmp_acc_desired & WRITE_DAC_ACCESS)
 269                                         tmp_acc_desired &= ~WRITE_DAC_ACCESS;
 270                                 if (tmp_acc_desired & READ_CONTROL_ACCESS)
 271                                         tmp_acc_desired &= ~READ_CONTROL_ACCESS;
 272                         }
 273                 }
 274         }
 275
 276         the_acl = sd->dacl;
 277
 278         if (tmp_acc_desired & MAXIMUM_ALLOWED_ACCESS) {
 279                 tmp_acc_desired &= ~MAXIMUM_ALLOWED_ACCESS;
 280                 return get_max_access( the_acl, token, acc_granted, tmp_acc_desired,
 281                                        status);
 282         }
 283
 284         for ( i = 0 ; i < the_acl->num_aces && tmp_acc_desired != 0; i++) {
 285                 SEC_ACE *ace = &the_acl->ace[i];
 286
 287                 DEBUGADD(10,("se_access_check: ACE %u: type %d, flags = 0x%02x, SID = %s mask = %x, current desired = %x\n",
 288                           (unsigned int)i, ace->type, ace->flags,
 289                           sid_to_string(sid_str, &ace->trustee),
 290                           (unsigned int) ace->info.mask,
 291                           (unsigned int)tmp_acc_desired ));
 292
 293                 tmp_acc_desired = check_ace( ace, token, tmp_acc_desired, status);
 294                 if (NT_STATUS_V(*status)) {
 295                         *acc_granted = 0;
 296                         DEBUG(5,("se_access_check: ACE %u denied with status %s.\n", (unsigned int)i, nt_errstr(*status)));
 297                         return False;
 298                 }
 299         }
 300
 301         /*
 302          * If there are no more desired permissions left then
 303          * access was allowed.
 304          */
 305
 306         if (tmp_acc_desired == 0) {
 307                 *acc_granted = acc_desired;
 308                 *status = NT_STATUS_OK;
 309                 DEBUG(5,("se_access_check: access (%x) granted.\n", (unsigned int)acc_desired ));
 310                 return True;
 311         }
 312
 313         *acc_granted = 0;
 314         *status = NT_STATUS_ACCESS_DENIED;
 315         DEBUG(5,("se_access_check: access (%x) denied.\n", (unsigned int)acc_desired ));
 316         return False;
 317 }
 318