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/*
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 <http://www.gnu.org/licenses/>.
*/
#include "includes.h"
extern struct current_user current_user;
#undef DBGC_CLASS
#define DBGC_CLASS DBGC_ACLS
/****************************************************************************
Helper function that gets a security descriptor by connection and
file name.
NOTE: This is transitional, in the sense that SMB_VFS_GET_NT_ACL really
should *not* get a files_struct pointer but a connection_struct ptr
(automatic by the vfs handle) and the file name and _use_ that!
****************************************************************************/
static NTSTATUS conn_get_nt_acl(TALLOC_CTX *mem_ctx,
struct connection_struct *conn,
const char *fname,
SMB_STRUCT_STAT *psbuf,
struct security_descriptor **psd)
{
NTSTATUS status;
struct files_struct *fsp = NULL;
struct security_descriptor *secdesc = NULL;
size_t secdesc_size;
if (!VALID_STAT(*psbuf)) {
if (SMB_VFS_STAT(conn, fname, psbuf) != 0) {
return map_nt_error_from_unix(errno);
}
}
/* fake a files_struct ptr: */
status = open_file_stat(conn, NULL, fname, psbuf, &fsp);
/* Perhaps it is a directory */
if (NT_STATUS_EQUAL(status, NT_STATUS_FILE_IS_A_DIRECTORY)) {
status = open_directory(conn, NULL, fname, psbuf,
READ_CONTROL_ACCESS,
FILE_SHARE_READ|FILE_SHARE_WRITE,
FILE_OPEN,
0,
FILE_ATTRIBUTE_DIRECTORY,
NULL, &fsp);
}
if (!NT_STATUS_IS_OK(status)) {
DEBUG(3, ("Unable to open file %s: %s\n", fname,
nt_errstr(status)));
return status;
}
secdesc_size = SMB_VFS_GET_NT_ACL(fsp, fname,
(OWNER_SECURITY_INFORMATION |
GROUP_SECURITY_INFORMATION |
DACL_SECURITY_INFORMATION),
&secdesc);
if (secdesc_size == 0) {
DEBUG(5, ("Unable to get NT ACL for file %s\n", fname));
return NT_STATUS_ACCESS_DENIED;
}
*psd = talloc_move(mem_ctx, &secdesc);
close_file(fsp, NORMAL_CLOSE);
return NT_STATUS_OK;
}
static bool can_access_file_acl(struct connection_struct *conn,
const char * fname, SMB_STRUCT_STAT *psbuf,
uint32_t access_mask)
{
bool result;
NTSTATUS status;
uint32_t access_granted;
struct security_descriptor *secdesc = NULL;
status = conn_get_nt_acl(talloc_tos(), conn, fname, psbuf, &secdesc);
if (!NT_STATUS_IS_OK(status)) {
DEBUG(5, ("Could not get acl: %s\n", nt_errstr(status)));
return false;
}
result = se_access_check(secdesc, current_user.nt_user_token,
access_mask, &access_granted, &status);
TALLOC_FREE(secdesc);
return result;
}
/****************************************************************************
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 char *fname)
{
SMB_STRUCT_STAT sbuf;
TALLOC_CTX *ctx = talloc_tos();
char *dname = NULL;
if (!CAN_WRITE(conn)) {
return False;
}
/* Get the parent directory permission mask and owners. */
if (!parent_dirname_talloc(ctx,
fname,
&dname,
NULL)) {
return False;
}
if(SMB_VFS_STAT(conn, dname, &sbuf) != 0) {
return False;
}
/* fast paths first */
if (!S_ISDIR(sbuf.st_mode)) {
return False;
}
if (current_user.ut.uid == 0 || conn->admin_user) {
/* I'm sorry sir, I didn't know you were root... */
return True;
}
/* Check primary owner write access. */
if (current_user.ut.uid == sbuf.st_uid) {
return (sbuf.st_mode & S_IWUSR) ? True : False;
}
#ifdef S_ISVTX
/* sticky bit means delete only by owner or root. */
if (sbuf.st_mode & S_ISVTX) {
SMB_STRUCT_STAT sbuf_file;
if(SMB_VFS_STAT(conn, fname, &sbuf_file) != 0) {
if (errno == ENOENT) {
/* If the file doesn't already exist then
* yes we'll be able to delete it. */
return True;
}
return False;
}
/*
* Patch from SATOH Fumiyasu <fumiyas@miraclelinux.com>
* for bug #3348. Don't assume owning sticky bit
* directory means write access allowed.
*/
if (current_user.ut.uid != sbuf_file.st_uid) {
return False;
}
}
#endif
/* now for ACL checks */
return can_access_file_acl(conn, dname, &sbuf, FILE_WRITE_DATA);
}
/****************************************************************************
Actually emulate the in-kernel access checking for read/write access. We need
this to successfully check for ability to write for dos filetimes.
Note this doesn't take into account share write permissions.
****************************************************************************/
bool can_access_file(connection_struct *conn, const char *fname, SMB_STRUCT_STAT *psbuf, uint32 access_mask)
{
if (!(access_mask & (FILE_READ_DATA|FILE_WRITE_DATA))) {
return False;
}
access_mask &= (FILE_READ_DATA|FILE_WRITE_DATA);
/* some fast paths first */
DEBUG(10,("can_access_file: requesting 0x%x on file %s\n",
(unsigned int)access_mask, fname ));
if (current_user.ut.uid == 0 || conn->admin_user) {
/* I'm sorry sir, I didn't know you were root... */
return True;
}
if (!VALID_STAT(*psbuf)) {
/* Get the file permission mask and owners. */
if(SMB_VFS_STAT(conn, fname, psbuf) != 0) {
return False;
}
}
/* Check primary owner access. */
if (current_user.ut.uid == psbuf->st_uid) {
switch (access_mask) {
case FILE_READ_DATA:
return (psbuf->st_mode & S_IRUSR) ? True : False;
case FILE_WRITE_DATA:
return (psbuf->st_mode & S_IWUSR) ? True : False;
default: /* FILE_READ_DATA|FILE_WRITE_DATA */
if ((psbuf->st_mode & (S_IWUSR|S_IRUSR)) == (S_IWUSR|S_IRUSR)) {
return True;
} else {
return False;
}
}
}
/* now for ACL checks */
return can_access_file_acl(conn, fname, psbuf, access_mask);
}
/****************************************************************************
Userspace check for write access.
Note this doesn't take into account share write permissions.
****************************************************************************/
bool can_write_to_file(connection_struct *conn, const char *fname, SMB_STRUCT_STAT *psbuf)
{
return can_access_file(conn, fname, psbuf, FILE_WRITE_DATA);
}
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