fe7ba1cc466e2221958242e9c8632078036f1ad7
[ira/wip.git] / source3 / smbd / file_access.c
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  */
29 bool can_access_file_acl(struct connection_struct *conn,
30                                 const char * fname,
31                                 uint32_t access_mask)
32 {
33         NTSTATUS status;
34         uint32_t access_granted;
35         struct security_descriptor *secdesc = NULL;
36
37         status = SMB_VFS_GET_NT_ACL(conn, fname,
38                                     (OWNER_SECURITY_INFORMATION |
39                                      GROUP_SECURITY_INFORMATION |
40                                      DACL_SECURITY_INFORMATION),
41                                     &secdesc);
42         if (!NT_STATUS_IS_OK(status)) {
43                 DEBUG(5, ("Could not get acl: %s\n", nt_errstr(status)));
44                 return false;
45         }
46
47         status = se_access_check(secdesc, conn->server_info->ptok,
48                                  access_mask, &access_granted);
49         TALLOC_FREE(secdesc);
50         return NT_STATUS_IS_OK(status);
51 }
52
53 /****************************************************************************
54  Actually emulate the in-kernel access checking for delete access. We need
55  this to successfully return ACCESS_DENIED on a file open for delete access.
56 ****************************************************************************/
57
58 bool can_delete_file_in_directory(connection_struct *conn, const char *fname)
59 {
60         SMB_STRUCT_STAT sbuf;
61         TALLOC_CTX *ctx = talloc_tos();
62         char *dname = NULL;
63
64         if (!CAN_WRITE(conn)) {
65                 return False;
66         }
67
68         /* Get the parent directory permission mask and owners. */
69         if (!parent_dirname(ctx, fname, &dname, NULL)) {
70                 return False;
71         }
72         if(SMB_VFS_STAT(conn, dname, &sbuf) != 0) {
73                 return False;
74         }
75
76         /* fast paths first */
77
78         if (!S_ISDIR(sbuf.st_mode)) {
79                 return False;
80         }
81         if (conn->server_info->utok.uid == 0 || conn->admin_user) {
82                 /* I'm sorry sir, I didn't know you were root... */
83                 return True;
84         }
85
86 #ifdef S_ISVTX
87         /* sticky bit means delete only by owner or root. */
88         if (sbuf.st_mode & S_ISVTX) {
89                 SMB_STRUCT_STAT sbuf_file;
90                 if(SMB_VFS_STAT(conn, fname, &sbuf_file) != 0) {
91                         if (errno == ENOENT) {
92                                 /* If the file doesn't already exist then
93                                  * yes we'll be able to delete it. */
94                                 return True;
95                         }
96                         return False;
97                 }
98                 /*
99                  * Patch from SATOH Fumiyasu <fumiyas@miraclelinux.com>
100                  * for bug #3348. Don't assume owning sticky bit
101                  * directory means write access allowed.
102                  */
103                 if (conn->server_info->utok.uid != sbuf_file.st_uid) {
104                         return False;
105                 }
106         }
107 #endif
108
109         /* now for ACL checks */
110
111         /*
112          * There's two ways to get the permission to delete a file: First by
113          * having the DELETE bit on the file itself and second if that does
114          * not help, by the DELETE_CHILD bit on the containing directory.
115          *
116          * Here we only check the directory permissions, we will
117          * check the file DELETE permission separately.
118          */
119
120         return can_access_file_acl(conn, dname, FILE_DELETE_CHILD);
121 }
122
123 /****************************************************************************
124  Actually emulate the in-kernel access checking for read/write access. We need
125  this to successfully check for ability to write for dos filetimes.
126  Note this doesn't take into account share write permissions.
127 ****************************************************************************/
128
129 bool can_access_file_data(connection_struct *conn, const char *fname, SMB_STRUCT_STAT *psbuf, uint32 access_mask)
130 {
131         if (!(access_mask & (FILE_READ_DATA|FILE_WRITE_DATA))) {
132                 return False;
133         }
134         access_mask &= (FILE_READ_DATA|FILE_WRITE_DATA);
135
136         /* some fast paths first */
137
138         DEBUG(10,("can_access_file_data: requesting 0x%x on file %s\n",
139                 (unsigned int)access_mask, fname ));
140
141         if (conn->server_info->utok.uid == 0 || conn->admin_user) {
142                 /* I'm sorry sir, I didn't know you were root... */
143                 return True;
144         }
145
146         if (!VALID_STAT(*psbuf)) {
147                 /* Get the file permission mask and owners. */
148                 if(SMB_VFS_STAT(conn, fname, psbuf) != 0) {
149                         return False;
150                 }
151         }
152
153         /* Check primary owner access. */
154         if (conn->server_info->utok.uid == psbuf->st_uid) {
155                 switch (access_mask) {
156                         case FILE_READ_DATA:
157                                 return (psbuf->st_mode & S_IRUSR) ? True : False;
158
159                         case FILE_WRITE_DATA:
160                                 return (psbuf->st_mode & S_IWUSR) ? True : False;
161
162                         default: /* FILE_READ_DATA|FILE_WRITE_DATA */
163
164                                 if ((psbuf->st_mode & (S_IWUSR|S_IRUSR)) == (S_IWUSR|S_IRUSR)) {
165                                         return True;
166                                 } else {
167                                         return False;
168                                 }
169                 }
170         }
171
172         /* now for ACL checks */
173
174         return can_access_file_acl(conn, fname, access_mask);
175 }
176
177 /****************************************************************************
178  Userspace check for write access.
179  Note this doesn't take into account share write permissions.
180 ****************************************************************************/
181
182 bool can_write_to_file(connection_struct *conn, const char *fname, SMB_STRUCT_STAT *psbuf)
183 {
184         return can_access_file_data(conn, fname, psbuf, FILE_WRITE_DATA);
185 }
186
187 /****************************************************************************
188  Check for an existing default Windows ACL on a directory.
189 ****************************************************************************/
190
191 bool directory_has_default_acl(connection_struct *conn, const char *fname)
192 {
193         /* returns talloced off tos. */
194         struct security_descriptor *secdesc = NULL;
195         unsigned int i;
196         NTSTATUS status = SMB_VFS_GET_NT_ACL(conn, fname,
197                                 DACL_SECURITY_INFORMATION, &secdesc);
198
199         if (!NT_STATUS_IS_OK(status) || secdesc == NULL) {
200                 return false;
201         }
202
203         for (i = 0; i < secdesc->dacl->num_aces; i++) {
204                 struct security_ace *psa = &secdesc->dacl->aces[i];
205                 if (psa->flags & (SEC_ACE_FLAG_OBJECT_INHERIT|
206                                 SEC_ACE_FLAG_CONTAINER_INHERIT)) {
207                         TALLOC_FREE(secdesc);
208                         return true;
209                 }
210         }
211         TALLOC_FREE(secdesc);
212         return false;
213 }