source: vendor/3.5.0/source3/smbd/file_access.c

Last change on this file was 414, checked in by Herwig Bauernfeind, 15 years ago

Samba 3.5.0: Initial import
File size: 7.4 KB
Line 
1/*
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.
6
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.
11
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.
16
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/>.
19*/
20
21#include "includes.h"
22
23#undef DBGC_CLASS
24#define DBGC_CLASS DBGC_ACLS
25
26/**
27 * Security descriptor / NT Token level access check function.
28 */
29bool can_access_file_acl(struct connection_struct *conn,
30 const struct smb_filename *smb_fname,
31 uint32_t access_mask)
32{
33 NTSTATUS status;
34 uint32_t access_granted;
35 struct security_descriptor *secdesc = NULL;
36 bool ret;
37
38 if (conn->server_info->utok.uid == 0 || conn->admin_user) {
39 /* I'm sorry sir, I didn't know you were root... */
40 return true;
41 }
42
43 status = SMB_VFS_GET_NT_ACL(conn, smb_fname->base_name,
44 (OWNER_SECURITY_INFORMATION |
45 GROUP_SECURITY_INFORMATION |
46 DACL_SECURITY_INFORMATION),
47 &secdesc);
48 if (!NT_STATUS_IS_OK(status)) {
49 DEBUG(5, ("Could not get acl: %s\n", nt_errstr(status)));
50 ret = false;
51 goto out;
52 }
53
54 status = se_access_check(secdesc, conn->server_info->ptok,
55 access_mask, &access_granted);
56 ret = NT_STATUS_IS_OK(status);
57 out:
58 TALLOC_FREE(secdesc);
59 return ret;
60}
61
62/****************************************************************************
63 Actually emulate the in-kernel access checking for delete access. We need
64 this to successfully return ACCESS_DENIED on a file open for delete access.
65****************************************************************************/
66
67bool can_delete_file_in_directory(connection_struct *conn,
68 struct smb_filename *smb_fname)
69{
70 TALLOC_CTX *ctx = talloc_tos();
71 char *dname = NULL;
72 struct smb_filename *smb_fname_parent = NULL;
73 NTSTATUS status;
74 bool ret;
75
76 if (!CAN_WRITE(conn)) {
77 return False;
78 }
79
80 /* Get the parent directory permission mask and owners. */
81 if (!parent_dirname(ctx, smb_fname->base_name, &dname, NULL)) {
82 return False;
83 }
84
85 status = create_synthetic_smb_fname(ctx, dname, NULL, NULL,
86 &smb_fname_parent);
87 if (!NT_STATUS_IS_OK(status)) {
88 ret = false;
89 goto out;
90 }
91
92 if(SMB_VFS_STAT(conn, smb_fname_parent) != 0) {
93 ret = false;
94 goto out;
95 }
96
97 /* fast paths first */
98
99 if (!S_ISDIR(smb_fname_parent->st.st_ex_mode)) {
100 ret = false;
101 goto out;
102 }
103 if (conn->server_info->utok.uid == 0 || conn->admin_user) {
104 /* I'm sorry sir, I didn't know you were root... */
105 ret = true;
106 goto out;
107 }
108
109#ifdef S_ISVTX
110 /* sticky bit means delete only by owner of file or by root or
111 * by owner of directory. */
112 if (smb_fname_parent->st.st_ex_mode & S_ISVTX) {
113 if(SMB_VFS_STAT(conn, smb_fname) != 0) {
114 if (errno == ENOENT) {
115 /* If the file doesn't already exist then
116 * yes we'll be able to delete it. */
117 ret = true;
118 goto out;
119 }
120 DEBUG(10,("can_delete_file_in_directory: can't "
121 "stat file %s (%s)",
122 smb_fname_str_dbg(smb_fname),
123 strerror(errno) ));
124 ret = false;
125 goto out;
126 }
127
128 /*
129 * Patch from SATOH Fumiyasu <fumiyas@miraclelinux.com>
130 * for bug #3348. Don't assume owning sticky bit
131 * directory means write access allowed.
132 * Fail to delete if we're not the owner of the file,
133 * or the owner of the directory as we have no possible
134 * chance of deleting. Otherwise, go on and check the ACL.
135 */
136 if ((conn->server_info->utok.uid !=
137 smb_fname_parent->st.st_ex_uid) &&
138 (conn->server_info->utok.uid != smb_fname->st.st_ex_uid)) {
139 DEBUG(10,("can_delete_file_in_directory: not "
140 "owner of file %s or directory %s",
141 smb_fname_str_dbg(smb_fname),
142 smb_fname_str_dbg(smb_fname_parent)));
143 ret = false;
144 goto out;
145 }
146 }
147#endif
148
149 /* now for ACL checks */
150
151 /*
152 * There's two ways to get the permission to delete a file: First by
153 * having the DELETE bit on the file itself and second if that does
154 * not help, by the DELETE_CHILD bit on the containing directory.
155 *
156 * Here we only check the directory permissions, we will
157 * check the file DELETE permission separately.
158 */
159
160 ret = can_access_file_acl(conn, smb_fname_parent, FILE_DELETE_CHILD);
161 out:
162 TALLOC_FREE(dname);
163 TALLOC_FREE(smb_fname_parent);
164 return ret;
165}
166
167/****************************************************************************
168 Actually emulate the in-kernel access checking for read/write access. We need
169 this to successfully check for ability to write for dos filetimes.
170 Note this doesn't take into account share write permissions.
171****************************************************************************/
172
173bool can_access_file_data(connection_struct *conn,
174 const struct smb_filename *smb_fname,
175 uint32 access_mask)
176{
177 if (!(access_mask & (FILE_READ_DATA|FILE_WRITE_DATA))) {
178 return False;
179 }
180 access_mask &= (FILE_READ_DATA|FILE_WRITE_DATA);
181
182 /* some fast paths first */
183
184 DEBUG(10,("can_access_file_data: requesting 0x%x on file %s\n",
185 (unsigned int)access_mask, smb_fname_str_dbg(smb_fname)));
186
187 if (conn->server_info->utok.uid == 0 || conn->admin_user) {
188 /* I'm sorry sir, I didn't know you were root... */
189 return True;
190 }
191
192 SMB_ASSERT(VALID_STAT(smb_fname->st));
193
194 /* Check primary owner access. */
195 if (conn->server_info->utok.uid == smb_fname->st.st_ex_uid) {
196 switch (access_mask) {
197 case FILE_READ_DATA:
198 return (smb_fname->st.st_ex_mode & S_IRUSR) ?
199 True : False;
200
201 case FILE_WRITE_DATA:
202 return (smb_fname->st.st_ex_mode & S_IWUSR) ?
203 True : False;
204
205 default: /* FILE_READ_DATA|FILE_WRITE_DATA */
206
207 if ((smb_fname->st.st_ex_mode &
208 (S_IWUSR|S_IRUSR)) ==
209 (S_IWUSR|S_IRUSR)) {
210 return True;
211 } else {
212 return False;
213 }
214 }
215 }
216
217 /* now for ACL checks */
218
219 return can_access_file_acl(conn, smb_fname, access_mask);
220}
221
222/****************************************************************************
223 Userspace check for write access.
224 Note this doesn't take into account share write permissions.
225****************************************************************************/
226
227bool can_write_to_file(connection_struct *conn,
228 const struct smb_filename *smb_fname)
229{
230 return can_access_file_data(conn, smb_fname, FILE_WRITE_DATA);
231}
232
233/****************************************************************************
234 Check for an existing default Windows ACL on a directory.
235****************************************************************************/
236
237bool directory_has_default_acl(connection_struct *conn, const char *fname)
238{
239 /* returns talloced off tos. */
240 struct security_descriptor *secdesc = NULL;
241 unsigned int i;
242 NTSTATUS status = SMB_VFS_GET_NT_ACL(conn, fname,
243 DACL_SECURITY_INFORMATION, &secdesc);
244
245 if (!NT_STATUS_IS_OK(status) || secdesc == NULL) {
246 return false;
247 }
248
249 for (i = 0; i < secdesc->dacl->num_aces; i++) {
250 struct security_ace *psa = &secdesc->dacl->aces[i];
251 if (psa->flags & (SEC_ACE_FLAG_OBJECT_INHERIT|
252 SEC_ACE_FLAG_CONTAINER_INHERIT)) {
253 TALLOC_FREE(secdesc);
254 return true;
255 }
256 }
257 TALLOC_FREE(secdesc);
258 return false;
259}
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