/*
   Unix SMB/CIFS implementation.

   security access checking routines

   Copyright (C) Andrew Tridgell 2004

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "includes.h"
#include "libcli/security/security.h"

/*
  perform a SEC_FLAG_MAXIMUM_ALLOWED access check
*/
static uint32_t access_check_max_allowed(const struct security_descriptor *sd, 
					 const struct security_token *token)
{
	uint32_t denied = 0, granted = 0;
	uint32_t i;
	
	if (security_token_has_sid(token, sd->owner_sid)) {
		granted |= SEC_STD_WRITE_DAC | SEC_STD_READ_CONTROL | SEC_STD_DELETE;
	} else if (security_token_has_privilege(token, SEC_PRIV_RESTORE)) {
		granted |= SEC_STD_DELETE;
	}

	if (sd->dacl == NULL) {
		return granted & ~denied;
	}
	
	for (i = 0;i<sd->dacl->num_aces; i++) {
		struct security_ace *ace = &sd->dacl->aces[i];

		if (ace->flags & SEC_ACE_FLAG_INHERIT_ONLY) {
			continue;
		}

		if (!security_token_has_sid(token, &ace->trustee)) {
			continue;
		}

		switch (ace->type) {
		case SEC_ACE_TYPE_ACCESS_ALLOWED:
			granted |= ace->access_mask;
			break;
		case SEC_ACE_TYPE_ACCESS_DENIED:
		case SEC_ACE_TYPE_ACCESS_DENIED_OBJECT:
			denied |= ace->access_mask;
			break;
		default:	/* Other ACE types not handled/supported */
			break;
		}
	}

	return granted & ~denied;
}

static const struct GUID *get_ace_object_type(struct security_ace *ace)
{
        struct GUID *type;

        if (ace->object.object.flags & SEC_ACE_OBJECT_TYPE_PRESENT)
                type = &ace->object.object.type.type;
        else if (ace->object.object.flags & SEC_ACE_INHERITED_OBJECT_TYPE_PRESENT)
                type = &ace->object.object.inherited_type.inherited_type; /* This doesn't look right. Is something wrong with the IDL? */
        else
                type = NULL;

        return type;

}

/*
  the main entry point for access checking. 
*/
NTSTATUS sec_access_check(const struct security_descriptor *sd, 
			  const struct security_token *token,
			  uint32_t access_desired,
			  uint32_t *access_granted)
{
	uint32_t i;
	uint32_t bits_remaining;

	*access_granted = access_desired;
	bits_remaining = access_desired;

	/* handle the maximum allowed flag */
	if (access_desired & SEC_FLAG_MAXIMUM_ALLOWED) {
		access_desired |= access_check_max_allowed(sd, token);
		access_desired &= ~SEC_FLAG_MAXIMUM_ALLOWED;
		*access_granted = access_desired;
		bits_remaining = access_desired & ~SEC_STD_DELETE;
	}

	if (access_desired & SEC_FLAG_SYSTEM_SECURITY) {
		if (security_token_has_privilege(token, SEC_PRIV_SECURITY)) {
			bits_remaining &= ~SEC_FLAG_SYSTEM_SECURITY;
		} else {
			return NT_STATUS_PRIVILEGE_NOT_HELD;
		}
	}

	/* a NULL dacl allows access */
	if ((sd->type & SEC_DESC_DACL_PRESENT) && sd->dacl == NULL) {
		*access_granted = access_desired;
		return NT_STATUS_OK;
	}

	/* the owner always gets SEC_STD_WRITE_DAC, SEC_STD_READ_CONTROL and SEC_STD_DELETE */
	if ((bits_remaining & (SEC_STD_WRITE_DAC|SEC_STD_READ_CONTROL|SEC_STD_DELETE)) &&
	    security_token_has_sid(token, sd->owner_sid)) {
		bits_remaining &= ~(SEC_STD_WRITE_DAC|SEC_STD_READ_CONTROL|SEC_STD_DELETE);
	}
	if ((bits_remaining & SEC_RIGHTS_PRIV_RESTORE) &&
	    security_token_has_privilege(token, SEC_PRIV_RESTORE)) {
		bits_remaining &= ~(SEC_RIGHTS_PRIV_RESTORE);
	}
	if ((bits_remaining & SEC_RIGHTS_PRIV_BACKUP) &&
	    security_token_has_privilege(token, SEC_PRIV_BACKUP)) {
		bits_remaining &= ~(SEC_RIGHTS_PRIV_BACKUP);
	}

	if (sd->dacl == NULL) {
		goto done;
	}

	/* check each ace in turn. */
	for (i=0; bits_remaining && i < sd->dacl->num_aces; i++) {
		struct security_ace *ace = &sd->dacl->aces[i];

		if (ace->flags & SEC_ACE_FLAG_INHERIT_ONLY) {
			continue;
		}

		if (!security_token_has_sid(token, &ace->trustee)) {
			continue;
		}

		switch (ace->type) {
		case SEC_ACE_TYPE_ACCESS_ALLOWED:
			bits_remaining &= ~ace->access_mask;
			break;
		case SEC_ACE_TYPE_ACCESS_DENIED:
		case SEC_ACE_TYPE_ACCESS_DENIED_OBJECT:
			if (bits_remaining & ace->access_mask) {
				return NT_STATUS_ACCESS_DENIED;
			}
			break;
		default:	/* Other ACE types not handled/supported */
			break;
		}
	}

done:
	if (bits_remaining != 0) {
		return NT_STATUS_ACCESS_DENIED;
	}

	return NT_STATUS_OK;
}

/* modified access check for the purposes of DS security
 * Lots of code duplication, it will ve united in just one
 * function eventually */

NTSTATUS sec_access_check_ds(const struct security_descriptor *sd,
			     const struct security_token *token,
			     uint32_t access_desired,
			     uint32_t *access_granted,
			     struct object_tree *tree,
			     struct dom_sid *replace_sid)
{
        uint32_t i;
        uint32_t bits_remaining;
        struct object_tree *node;
        const struct GUID *type;
	struct dom_sid *ps_sid = dom_sid_parse_talloc(NULL, SID_NT_SELF);

        *access_granted = access_desired;
        bits_remaining = access_desired;

        /* handle the maximum allowed flag */
        if (access_desired & SEC_FLAG_MAXIMUM_ALLOWED) {
                access_desired |= access_check_max_allowed(sd, token);
                access_desired &= ~SEC_FLAG_MAXIMUM_ALLOWED;
                *access_granted = access_desired;
                bits_remaining = access_desired & ~SEC_STD_DELETE;
        }

        if (access_desired & SEC_FLAG_SYSTEM_SECURITY) {
                if (security_token_has_privilege(token, SEC_PRIV_SECURITY)) {
                        bits_remaining &= ~SEC_FLAG_SYSTEM_SECURITY;
                } else {
                        return NT_STATUS_PRIVILEGE_NOT_HELD;
                }
        }

        /* a NULL dacl allows access */
        if ((sd->type & SEC_DESC_DACL_PRESENT) && sd->dacl == NULL) {
		*access_granted = access_desired;
                return NT_STATUS_OK;
        }

        /* the owner always gets SEC_STD_WRITE_DAC, SEC_STD_READ_CONTROL and SEC_STD_DELETE */
        if ((bits_remaining & (SEC_STD_WRITE_DAC|SEC_STD_READ_CONTROL|SEC_STD_DELETE)) &&
            security_token_has_sid(token, sd->owner_sid)) {
                bits_remaining &= ~(SEC_STD_WRITE_DAC|SEC_STD_READ_CONTROL|SEC_STD_DELETE);
        }
        if ((bits_remaining & SEC_STD_DELETE) &&
            security_token_has_privilege(token, SEC_PRIV_RESTORE)) {
                bits_remaining &= ~SEC_STD_DELETE;
        }

        if (sd->dacl == NULL) {
                goto done;
        }

        /* check each ace in turn. */
        for (i=0; bits_remaining && i < sd->dacl->num_aces; i++) {
		struct dom_sid *trustee;
		struct security_ace *ace = &sd->dacl->aces[i];

                if (ace->flags & SEC_ACE_FLAG_INHERIT_ONLY) {
                        continue;
                }
		if (dom_sid_equal(&ace->trustee, ps_sid) && replace_sid) {
			trustee = replace_sid;
		}
		else
		{
			trustee = &ace->trustee;
		}
                if (!security_token_has_sid(token, trustee)) {
                        continue;
                }

                switch (ace->type) {
                case SEC_ACE_TYPE_ACCESS_ALLOWED:
                        if (tree)
                                object_tree_modify_access(tree, ace->access_mask);

                        bits_remaining &= ~ace->access_mask;
                        break;
                case SEC_ACE_TYPE_ACCESS_DENIED:
                        if (bits_remaining & ace->access_mask) {
                                return NT_STATUS_ACCESS_DENIED;
                        }
                        break;
                case SEC_ACE_TYPE_ACCESS_DENIED_OBJECT:
                case SEC_ACE_TYPE_ACCESS_ALLOWED_OBJECT:
                        /* check only in case we have provided a tree,
                         * the ACE has an object type and that type
                         * is in the tree                           */
                        type = get_ace_object_type(ace);

                        if (!tree)
                                continue;

                        if (!type)
                                node = tree;
                        else
                                if (!(node = get_object_tree_by_GUID(tree, type)))
                                        continue;

                        if (ace->type == SEC_ACE_TYPE_ACCESS_ALLOWED_OBJECT) {
                                object_tree_modify_access(node, ace->access_mask);
				if (node->remaining_access == 0) {
					return NT_STATUS_OK;
				}
                        }
                        else {
                                if (node->remaining_access & ace->access_mask){
                                        return NT_STATUS_ACCESS_DENIED;
                                }
                        }
                        break;
                default:        /* Other ACE types not handled/supported */
                        break;
                }
        }

done:
        if (bits_remaining != 0) {
                return NT_STATUS_ACCESS_DENIED;
        }

        return NT_STATUS_OK;
}