2 Unix SMB/CIFS implementation.
3 Check access to files based on security descriptors.
4 Copyright (C) Jeremy Allison 2005-2006.
5 Copyright (C) Michael Adam 2007.
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 3 of the License, or
10 (at your option) any later version.
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.
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>.
22 #include "system/filesys.h"
23 #include "../libcli/security/security.h"
24 #include "../librpc/gen_ndr/ndr_security.h"
25 #include "smbd/smbd.h"
28 #define DBGC_CLASS DBGC_ACLS
31 * Security descriptor / NT Token level access check function.
33 bool can_access_file_acl(struct connection_struct
*conn
,
34 const struct smb_filename
*smb_fname
,
38 uint32_t access_granted
;
39 struct security_descriptor
*secdesc
= NULL
;
42 if (get_current_uid(conn
) == (uid_t
)0) {
43 /* I'm sorry sir, I didn't know you were root... */
47 if (access_mask
== DELETE_ACCESS
&&
48 VALID_STAT(smb_fname
->st
) &&
49 S_ISLNK(smb_fname
->st
.st_ex_mode
)) {
50 /* We can always delete a symlink. */
54 status
= SMB_VFS_GET_NT_ACL(conn
, smb_fname
->base_name
,
59 if (!NT_STATUS_IS_OK(status
)) {
60 DEBUG(5, ("Could not get acl: %s\n", nt_errstr(status
)));
65 status
= se_access_check(secdesc
, get_current_nttok(conn
),
66 access_mask
, &access_granted
);
67 ret
= NT_STATUS_IS_OK(status
);
69 if (DEBUGLEVEL
>= 10) {
70 DEBUG(10,("can_access_file_acl for file %s "
71 "access_mask 0x%x, access_granted 0x%x "
73 smb_fname_str_dbg(smb_fname
),
74 (unsigned int)access_mask
,
75 (unsigned int)access_granted
,
76 ret
? "ALLOWED" : "DENIED" ));
77 NDR_PRINT_DEBUG(security_descriptor
, secdesc
);
84 /****************************************************************************
85 Actually emulate the in-kernel access checking for delete access. We need
86 this to successfully return ACCESS_DENIED on a file open for delete access.
87 ****************************************************************************/
89 bool can_delete_file_in_directory(connection_struct
*conn
,
90 struct smb_filename
*smb_fname
)
92 TALLOC_CTX
*ctx
= talloc_tos();
94 struct smb_filename
*smb_fname_parent
= NULL
;
98 if (!CAN_WRITE(conn
)) {
102 if (!lp_acl_check_permissions(SNUM(conn
))) {
103 /* This option means don't check. */
107 /* Get the parent directory permission mask and owners. */
108 if (!parent_dirname(ctx
, smb_fname
->base_name
, &dname
, NULL
)) {
112 status
= create_synthetic_smb_fname(ctx
, dname
, NULL
, NULL
,
114 if (!NT_STATUS_IS_OK(status
)) {
119 if(SMB_VFS_STAT(conn
, smb_fname_parent
) != 0) {
124 /* fast paths first */
126 if (!S_ISDIR(smb_fname_parent
->st
.st_ex_mode
)) {
130 if (get_current_uid(conn
) == (uid_t
)0) {
131 /* I'm sorry sir, I didn't know you were root... */
137 /* sticky bit means delete only by owner of file or by root or
138 * by owner of directory. */
139 if (smb_fname_parent
->st
.st_ex_mode
& S_ISVTX
) {
140 if (!VALID_STAT(smb_fname
->st
)) {
141 /* If the file doesn't already exist then
142 * yes we'll be able to delete it. */
148 * Patch from SATOH Fumiyasu <fumiyas@miraclelinux.com>
149 * for bug #3348. Don't assume owning sticky bit
150 * directory means write access allowed.
151 * Fail to delete if we're not the owner of the file,
152 * or the owner of the directory as we have no possible
153 * chance of deleting. Otherwise, go on and check the ACL.
155 if ((get_current_uid(conn
) !=
156 smb_fname_parent
->st
.st_ex_uid
) &&
157 (get_current_uid(conn
) != smb_fname
->st
.st_ex_uid
)) {
158 DEBUG(10,("can_delete_file_in_directory: not "
159 "owner of file %s or directory %s",
160 smb_fname_str_dbg(smb_fname
),
161 smb_fname_str_dbg(smb_fname_parent
)));
168 /* now for ACL checks */
171 * There's two ways to get the permission to delete a file: First by
172 * having the DELETE bit on the file itself and second if that does
173 * not help, by the DELETE_CHILD bit on the containing directory.
175 * Here we only check the directory permissions, we will
176 * check the file DELETE permission separately.
179 ret
= can_access_file_acl(conn
, smb_fname_parent
, FILE_DELETE_CHILD
);
182 TALLOC_FREE(smb_fname_parent
);
186 /****************************************************************************
187 Actually emulate the in-kernel access checking for read/write access. We need
188 this to successfully check for ability to write for dos filetimes.
189 Note this doesn't take into account share write permissions.
190 ****************************************************************************/
192 bool can_access_file_data(connection_struct
*conn
,
193 const struct smb_filename
*smb_fname
,
196 if (!(access_mask
& (FILE_READ_DATA
|FILE_WRITE_DATA
))) {
199 access_mask
&= (FILE_READ_DATA
|FILE_WRITE_DATA
);
201 /* some fast paths first */
203 DEBUG(10,("can_access_file_data: requesting 0x%x on file %s\n",
204 (unsigned int)access_mask
, smb_fname_str_dbg(smb_fname
)));
206 if (get_current_uid(conn
) == (uid_t
)0) {
207 /* I'm sorry sir, I didn't know you were root... */
211 SMB_ASSERT(VALID_STAT(smb_fname
->st
));
213 /* Check primary owner access. */
214 if (get_current_uid(conn
) == smb_fname
->st
.st_ex_uid
) {
215 switch (access_mask
) {
217 return (smb_fname
->st
.st_ex_mode
& S_IRUSR
) ?
220 case FILE_WRITE_DATA
:
221 return (smb_fname
->st
.st_ex_mode
& S_IWUSR
) ?
224 default: /* FILE_READ_DATA|FILE_WRITE_DATA */
226 if ((smb_fname
->st
.st_ex_mode
&
227 (S_IWUSR
|S_IRUSR
)) ==
236 /* now for ACL checks */
238 return can_access_file_acl(conn
, smb_fname
, access_mask
);
241 /****************************************************************************
242 Userspace check for write access.
243 Note this doesn't take into account share write permissions.
244 ****************************************************************************/
246 bool can_write_to_file(connection_struct
*conn
,
247 const struct smb_filename
*smb_fname
)
249 return can_access_file_data(conn
, smb_fname
, FILE_WRITE_DATA
);
252 /****************************************************************************
253 Check for an existing default Windows ACL on a directory.
254 ****************************************************************************/
256 bool directory_has_default_acl(connection_struct
*conn
, const char *fname
)
258 /* returns talloced off tos. */
259 struct security_descriptor
*secdesc
= NULL
;
261 NTSTATUS status
= SMB_VFS_GET_NT_ACL(conn
, fname
,
262 SECINFO_DACL
, &secdesc
);
264 if (!NT_STATUS_IS_OK(status
) || secdesc
== NULL
) {
268 for (i
= 0; i
< secdesc
->dacl
->num_aces
; i
++) {
269 struct security_ace
*psa
= &secdesc
->dacl
->aces
[i
];
270 if (psa
->flags
& (SEC_ACE_FLAG_OBJECT_INHERIT
|
271 SEC_ACE_FLAG_CONTAINER_INHERIT
)) {
272 TALLOC_FREE(secdesc
);
276 TALLOC_FREE(secdesc
);