source/lib/util_seaccess.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    Copyright (C) Andrew Tridgell 2004
   5    Copyright (C) Gerald Carter 2005
   6    Copyright (C) Volker Lendecke 2007
   7    Copyright (C) Jeremy Allison 2008
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 3 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  21 */
  22
  23 #include "includes.h"
  24
  25 extern NT_USER_TOKEN anonymous_token;
  26
  27 /* Map generic access rights to object specific rights.  This technique is
  28    used to give meaning to assigning read, write, execute and all access to
  29    objects.  Each type of object has its own mapping of generic to object
  30    specific access rights. */
  31
  32 void se_map_generic(uint32 *access_mask, const struct generic_mapping *mapping)
  33 {
  34         uint32 old_mask = *access_mask;
  35
  36         if (*access_mask & GENERIC_READ_ACCESS) {
  37                 *access_mask &= ~GENERIC_READ_ACCESS;
  38                 *access_mask |= mapping->generic_read;
  39         }
  40
  41         if (*access_mask & GENERIC_WRITE_ACCESS) {
  42                 *access_mask &= ~GENERIC_WRITE_ACCESS;
  43                 *access_mask |= mapping->generic_write;
  44         }
  45
  46         if (*access_mask & GENERIC_EXECUTE_ACCESS) {
  47                 *access_mask &= ~GENERIC_EXECUTE_ACCESS;
  48                 *access_mask |= mapping->generic_execute;
  49         }
  50
  51         if (*access_mask & GENERIC_ALL_ACCESS) {
  52                 *access_mask &= ~GENERIC_ALL_ACCESS;
  53                 *access_mask |= mapping->generic_all;
  54         }
  55
  56         if (old_mask != *access_mask) {
  57                 DEBUG(10, ("se_map_generic(): mapped mask 0x%08x to 0x%08x\n",
  58                            old_mask, *access_mask));
  59         }
  60 }
  61
  62 /* Map generic access rights to object specific rights for all the ACE's
  63  * in a security_acl.
  64  */
  65
  66 void security_acl_map_generic(struct security_acl *sa,
  67                                 const struct generic_mapping *mapping)
  68 {
  69         unsigned int i;
  70
  71         if (!sa) {
  72                 return;
  73         }
  74
  75         for (i = 0; i < sa->num_aces; i++) {
  76                 se_map_generic(&sa->aces[i].access_mask, mapping);
  77         }
  78 }
  79
  80 /* Map standard access rights to object specific rights.  This technique is
  81    used to give meaning to assigning read, write, execute and all access to
  82    objects.  Each type of object has its own mapping of standard to object
  83    specific access rights. */
  84
  85 void se_map_standard(uint32 *access_mask, struct standard_mapping *mapping)
  86 {
  87         uint32 old_mask = *access_mask;
  88
  89         if (*access_mask & SEC_STD_READ_CONTROL) {
  90                 *access_mask &= ~SEC_STD_READ_CONTROL;
  91                 *access_mask |= mapping->std_read;
  92         }
  93
  94         if (*access_mask & (SEC_STD_DELETE|SEC_STD_WRITE_DAC|SEC_STD_WRITE_OWNER|SEC_STD_SYNCHRONIZE)) {
  95                 *access_mask &= ~(SEC_STD_DELETE|SEC_STD_WRITE_DAC|SEC_STD_WRITE_OWNER|SEC_STD_SYNCHRONIZE);
  96                 *access_mask |= mapping->std_all;
  97         }
  98
  99         if (old_mask != *access_mask) {
 100                 DEBUG(10, ("se_map_standard(): mapped mask 0x%08x to 0x%08x\n",
 101                            old_mask, *access_mask));
 102         }
 103 }
 104
 105 /*
 106   perform a SEC_FLAG_MAXIMUM_ALLOWED access check
 107 */
 108 static uint32_t access_check_max_allowed(const struct security_descriptor *sd,
 109                                         const NT_USER_TOKEN *token)
 110 {
 111         uint32_t denied = 0, granted = 0;
 112         unsigned i;
 113
 114         if (is_sid_in_token(token, sd->owner_sid)) {
 115                 granted |= SEC_STD_WRITE_DAC | SEC_STD_READ_CONTROL | SEC_STD_DELETE;
 116         } else if (user_has_privileges(token, &se_restore)) {
 117                 granted |= SEC_STD_DELETE;
 118         }
 119
 120         if (sd->dacl == NULL) {
 121                 return granted & ~denied;
 122         }
 123
 124         for (i = 0;i<sd->dacl->num_aces; i++) {
 125                 struct security_ace *ace = &sd->dacl->aces[i];
 126
 127                 if (ace->flags & SEC_ACE_FLAG_INHERIT_ONLY) {
 128                         continue;
 129                 }
 130
 131                 if (!is_sid_in_token(token, &ace->trustee)) {
 132                         continue;
 133                 }
 134
 135                 switch (ace->type) {
 136                 case SEC_ACE_TYPE_ACCESS_ALLOWED:
 137                         granted |= ace->access_mask;
 138                         break;
 139                 case SEC_ACE_TYPE_ACCESS_DENIED:
 140                 case SEC_ACE_TYPE_ACCESS_DENIED_OBJECT:
 141                         denied |= ace->access_mask;
 142                         break;
 143                 default:        /* Other ACE types not handled/supported */
 144                         break;
 145                 }
 146         }
 147
 148         return granted & ~denied;
 149 }
 150
 151 /*
 152   the main entry point for access checking.
 153 */
 154 NTSTATUS se_access_check(const struct security_descriptor *sd,
 155                           const NT_USER_TOKEN *token,
 156                           uint32_t access_desired,
 157                           uint32_t *access_granted)
 158 {
 159         int i;
 160         uint32_t bits_remaining;
 161
 162         *access_granted = access_desired;
 163         bits_remaining = access_desired;
 164
 165         /* handle the maximum allowed flag */
 166         if (access_desired & SEC_FLAG_MAXIMUM_ALLOWED) {
 167                 uint32_t orig_access_desired = access_desired;
 168
 169                 access_desired |= access_check_max_allowed(sd, token);
 170                 access_desired &= ~SEC_FLAG_MAXIMUM_ALLOWED;
 171                 *access_granted = access_desired;
 172                 bits_remaining = access_desired & ~SEC_STD_DELETE;
 173
 174                 DEBUG(10,("se_access_check: MAX desired = 0x%x, granted = 0x%x, remaining = 0x%x\n",
 175                         orig_access_desired,
 176                         *access_granted,
 177                         bits_remaining));
 178         }
 179
 180 #if 0
 181         /* We need to support SeSecurityPrivilege for this. */
 182
 183         if (access_desired & SEC_FLAG_SYSTEM_SECURITY) {
 184                 if (user_has_privileges(token, &sec_security)) {
 185                         bits_remaining &= ~SEC_FLAG_SYSTEM_SECURITY;
 186                 } else {
 187                         return NT_STATUS_PRIVILEGE_NOT_HELD;
 188                 }
 189         }
 190 #endif
 191
 192         /* a NULL dacl allows access */
 193         if ((sd->type & SEC_DESC_DACL_PRESENT) && sd->dacl == NULL) {
 194                 *access_granted = access_desired;
 195                 return NT_STATUS_OK;
 196         }
 197
 198         /* the owner always gets SEC_STD_WRITE_DAC, SEC_STD_READ_CONTROL and SEC_STD_DELETE */
 199         if ((bits_remaining & (SEC_STD_WRITE_DAC|SEC_STD_READ_CONTROL|SEC_STD_DELETE)) &&
 200             is_sid_in_token(token, sd->owner_sid)) {
 201                 bits_remaining &= ~(SEC_STD_WRITE_DAC|SEC_STD_READ_CONTROL|SEC_STD_DELETE);
 202         }
 203         if ((bits_remaining & SEC_STD_DELETE) &&
 204             user_has_privileges(token, &se_restore)) {
 205                 bits_remaining &= ~SEC_STD_DELETE;
 206         }
 207
 208         if (sd->dacl == NULL) {
 209                 goto done;
 210         }
 211
 212         /* check each ace in turn. */
 213         for (i=0; bits_remaining && i < sd->dacl->num_aces; i++) {
 214                 struct security_ace *ace = &sd->dacl->aces[i];
 215
 216                 if (ace->flags & SEC_ACE_FLAG_INHERIT_ONLY) {
 217                         continue;
 218                 }
 219
 220                 if (!is_sid_in_token(token, &ace->trustee)) {
 221                         continue;
 222                 }
 223
 224                 switch (ace->type) {
 225                 case SEC_ACE_TYPE_ACCESS_ALLOWED:
 226                         bits_remaining &= ~ace->access_mask;
 227                         break;
 228                 case SEC_ACE_TYPE_ACCESS_DENIED:
 229                 case SEC_ACE_TYPE_ACCESS_DENIED_OBJECT:
 230                         if (bits_remaining & ace->access_mask) {
 231                                 return NT_STATUS_ACCESS_DENIED;
 232                         }
 233                         break;
 234                 default:        /* Other ACE types not handled/supported */
 235                         break;
 236                 }
 237         }
 238
 239 done:
 240         if (bits_remaining != 0) {
 241                 return NT_STATUS_ACCESS_DENIED;
 242         }
 243
 244         return NT_STATUS_OK;
 245 }
 246
 247 /*******************************************************************
 248  samr_make_sam_obj_sd
 249  ********************************************************************/
 250
 251 NTSTATUS samr_make_sam_obj_sd(TALLOC_CTX *ctx, SEC_DESC **psd, size_t *sd_size)
 252 {
 253         DOM_SID adm_sid;
 254         DOM_SID act_sid;
 255
 256         SEC_ACE ace[3];
 257
 258         SEC_ACL *psa = NULL;
 259
 260         sid_copy(&adm_sid, &global_sid_Builtin);
 261         sid_append_rid(&adm_sid, BUILTIN_ALIAS_RID_ADMINS);
 262
 263         sid_copy(&act_sid, &global_sid_Builtin);
 264         sid_append_rid(&act_sid, BUILTIN_ALIAS_RID_ACCOUNT_OPS);
 265
 266         /*basic access for every one*/
 267         init_sec_ace(&ace[0], &global_sid_World, SEC_ACE_TYPE_ACCESS_ALLOWED,
 268                 GENERIC_RIGHTS_SAM_EXECUTE | GENERIC_RIGHTS_SAM_READ, 0);
 269
 270         /*full access for builtin aliases Administrators and Account Operators*/
 271         init_sec_ace(&ace[1], &adm_sid,
 272                 SEC_ACE_TYPE_ACCESS_ALLOWED, GENERIC_RIGHTS_SAM_ALL_ACCESS, 0);
 273         init_sec_ace(&ace[2], &act_sid,
 274                 SEC_ACE_TYPE_ACCESS_ALLOWED, GENERIC_RIGHTS_SAM_ALL_ACCESS, 0);
 275
 276         if ((psa = make_sec_acl(ctx, NT4_ACL_REVISION, 3, ace)) == NULL)
 277                 return NT_STATUS_NO_MEMORY;
 278
 279         if ((*psd = make_sec_desc(ctx, SECURITY_DESCRIPTOR_REVISION_1,
 280                                   SEC_DESC_SELF_RELATIVE, NULL, NULL, NULL,
 281                                   psa, sd_size)) == NULL)
 282                 return NT_STATUS_NO_MEMORY;
 283
 284         return NT_STATUS_OK;
 285 }