/*
Unix SMB/CIFS implementation.
Check access to files based on security descriptors.
Copyright (C) Jeremy Allison 2005-2006.
Copyright (C) Michael Adam 2007.
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 .
*/
#include "includes.h"
#include "system/filesys.h"
#include "../libcli/security/security.h"
#include "../librpc/gen_ndr/ndr_security.h"
#include "smbd/smbd.h"
#undef DBGC_CLASS
#define DBGC_CLASS DBGC_ACLS
/**
* Security descriptor / NT Token level access check function.
*/
bool can_access_file_acl(struct connection_struct *conn,
const struct smb_filename *smb_fname,
uint32_t access_mask)
{
NTSTATUS status;
uint32_t access_granted;
struct security_descriptor *secdesc = NULL;
bool ret;
if (get_current_uid(conn) == (uid_t)0) {
/* I'm sorry sir, I didn't know you were root... */
return true;
}
status = SMB_VFS_GET_NT_ACL(conn, smb_fname->base_name,
(SECINFO_OWNER |
SECINFO_GROUP |
SECINFO_DACL),
&secdesc);
if (!NT_STATUS_IS_OK(status)) {
DEBUG(5, ("Could not get acl: %s\n", nt_errstr(status)));
ret = false;
goto out;
}
status = se_access_check(secdesc, get_current_nttok(conn),
access_mask, &access_granted);
ret = NT_STATUS_IS_OK(status);
if (DEBUGLEVEL >= 10) {
DEBUG(10,("can_access_file_acl for file %s "
"access_mask 0x%x, access_granted 0x%x "
"access %s\n",
smb_fname_str_dbg(smb_fname),
(unsigned int)access_mask,
(unsigned int)access_granted,
ret ? "ALLOWED" : "DENIED" ));
NDR_PRINT_DEBUG(security_descriptor, secdesc);
}
out:
TALLOC_FREE(secdesc);
return ret;
}
/****************************************************************************
Actually emulate the in-kernel access checking for delete access. We need
this to successfully return ACCESS_DENIED on a file open for delete access.
****************************************************************************/
bool can_delete_file_in_directory(connection_struct *conn,
const struct smb_filename *smb_fname)
{
TALLOC_CTX *ctx = talloc_tos();
char *dname = NULL;
struct smb_filename *smb_fname_parent = NULL;
NTSTATUS status;
bool ret;
if (!CAN_WRITE(conn)) {
return False;
}
if (!lp_acl_check_permissions(SNUM(conn))) {
/* This option means don't check. */
return true;
}
/* Get the parent directory permission mask and owners. */
if (!parent_dirname(ctx, smb_fname->base_name, &dname, NULL)) {
return False;
}
status = create_synthetic_smb_fname(ctx, dname, NULL, NULL,
&smb_fname_parent);
if (!NT_STATUS_IS_OK(status)) {
ret = false;
goto out;
}
if(SMB_VFS_STAT(conn, smb_fname_parent) != 0) {
ret = false;
goto out;
}
/* fast paths first */
if (!S_ISDIR(smb_fname_parent->st.st_ex_mode)) {
ret = false;
goto out;
}
if (get_current_uid(conn) == (uid_t)0) {
/* I'm sorry sir, I didn't know you were root... */
ret = true;
goto out;
}
#ifdef S_ISVTX
/* sticky bit means delete only by owner of file or by root or
* by owner of directory. */
if (smb_fname_parent->st.st_ex_mode & S_ISVTX) {
if (!VALID_STAT(smb_fname->st)) {
/* If the file doesn't already exist then
* yes we'll be able to delete it. */
ret = true;
goto out;
}
/*
* Patch from SATOH Fumiyasu
* for bug #3348. Don't assume owning sticky bit
* directory means write access allowed.
* Fail to delete if we're not the owner of the file,
* or the owner of the directory as we have no possible
* chance of deleting. Otherwise, go on and check the ACL.
*/
if ((get_current_uid(conn) !=
smb_fname_parent->st.st_ex_uid) &&
(get_current_uid(conn) != smb_fname->st.st_ex_uid)) {
DEBUG(10,("can_delete_file_in_directory: not "
"owner of file %s or directory %s",
smb_fname_str_dbg(smb_fname),
smb_fname_str_dbg(smb_fname_parent)));
ret = false;
goto out;
}
}
#endif
/* now for ACL checks */
/*
* There's two ways to get the permission to delete a file: First by
* having the DELETE bit on the file itself and second if that does
* not help, by the DELETE_CHILD bit on the containing directory.
*
* Here we only check the directory permissions, we will
* check the file DELETE permission separately.
*/
ret = can_access_file_acl(conn, smb_fname_parent, FILE_DELETE_CHILD);
out:
TALLOC_FREE(dname);
TALLOC_FREE(smb_fname_parent);
return ret;
}
/****************************************************************************
Userspace check for write access.
Note this doesn't take into account share write permissions.
****************************************************************************/
bool can_write_to_file(connection_struct *conn,
const struct smb_filename *smb_fname)
{
return NT_STATUS_IS_OK(smbd_check_access_rights(conn,
smb_fname,
FILE_WRITE_DATA));
}
/****************************************************************************
Check for an existing default Windows ACL on a directory.
****************************************************************************/
bool directory_has_default_acl(connection_struct *conn, const char *fname)
{
/* returns talloced off tos. */
struct security_descriptor *secdesc = NULL;
unsigned int i;
NTSTATUS status = SMB_VFS_GET_NT_ACL(conn, fname,
SECINFO_DACL, &secdesc);
if (!NT_STATUS_IS_OK(status) || secdesc == NULL) {
return false;
}
for (i = 0; i < secdesc->dacl->num_aces; i++) {
struct security_ace *psa = &secdesc->dacl->aces[i];
if (psa->flags & (SEC_ACE_FLAG_OBJECT_INHERIT|
SEC_ACE_FLAG_CONTAINER_INHERIT)) {
TALLOC_FREE(secdesc);
return true;
}
}
TALLOC_FREE(secdesc);
return false;
}