1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
|
/*
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"
#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 char * fname,
uint32_t access_mask)
{
bool result;
NTSTATUS status;
uint32_t access_granted;
struct security_descriptor *secdesc = NULL;
status = SMB_VFS_GET_NT_ACL(conn, fname,
(OWNER_SECURITY_INFORMATION |
GROUP_SECURITY_INFORMATION |
DACL_SECURITY_INFORMATION),
&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, conn->server_info->ptok,
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 (conn->server_info->uid == 0 || conn->admin_user) {
/* I'm sorry sir, I didn't know you were root... */
return True;
}
#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 (conn->server_info->uid != sbuf_file.st_uid) {
return False;
}
}
#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 check the other way round because with just posix
* permissions looking at the file itself will never grant DELETE, so
* by looking at the directory first we save one get_acl call.
*/
if (can_access_file_acl(conn, dname, FILE_DELETE_CHILD)) {
return true;
}
return can_access_file_acl(conn, fname, DELETE_ACCESS);
}
/****************************************************************************
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_data(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_data: requesting 0x%x on file %s\n",
(unsigned int)access_mask, fname ));
if (conn->server_info->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 (conn->server_info->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, 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_data(conn, fname, psbuf, 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,
DACL_SECURITY_INFORMATION, &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;
}
|
