smbd: some write time fixes
[tprouty/samba.git] / source / 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 extern struct current_user current_user;
24
25 #undef  DBGC_CLASS
26 #define DBGC_CLASS DBGC_ACLS
27
28 static bool can_access_file_acl(struct connection_struct *conn,
29                                 const char * fname, SMB_STRUCT_STAT *psbuf,
30                                 uint32_t access_mask)
31 {
32         bool result;
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         result = se_access_check(secdesc, current_user.nt_user_token,
48                                  access_mask, &access_granted, &status);
49         TALLOC_FREE(secdesc);
50         return result;
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_talloc(ctx,
70                                 fname,
71                                 &dname,
72                                 NULL)) {
73                 return False;
74         }
75         if(SMB_VFS_STAT(conn, dname, &sbuf) != 0) {
76                 return False;
77         }
78
79         /* fast paths first */
80
81         if (!S_ISDIR(sbuf.st_mode)) {
82                 return False;
83         }
84         if (current_user.ut.uid == 0 || conn->admin_user) {
85                 /* I'm sorry sir, I didn't know you were root... */
86                 return True;
87         }
88
89         /* Check primary owner write access. */
90         if (current_user.ut.uid == sbuf.st_uid) {
91                 return (sbuf.st_mode & S_IWUSR) ? True : False;
92         }
93
94 #ifdef S_ISVTX
95         /* sticky bit means delete only by owner or root. */
96         if (sbuf.st_mode & S_ISVTX) {
97                 SMB_STRUCT_STAT sbuf_file;
98                 if(SMB_VFS_STAT(conn, fname, &sbuf_file) != 0) {
99                         if (errno == ENOENT) {
100                                 /* If the file doesn't already exist then
101                                  * yes we'll be able to delete it. */
102                                 return True;
103                         }
104                         return False;
105                 }
106                 /*
107                  * Patch from SATOH Fumiyasu <fumiyas@miraclelinux.com>
108                  * for bug #3348. Don't assume owning sticky bit
109                  * directory means write access allowed.
110                  */
111                 if (current_user.ut.uid != sbuf_file.st_uid) {
112                         return False;
113                 }
114         }
115 #endif
116
117         /* now for ACL checks */
118
119         return can_access_file_acl(conn, dname, &sbuf, FILE_WRITE_DATA);
120 }
121
122 /****************************************************************************
123  Actually emulate the in-kernel access checking for read/write access. We need
124  this to successfully check for ability to write for dos filetimes.
125  Note this doesn't take into account share write permissions.
126 ****************************************************************************/
127
128 bool can_access_file(connection_struct *conn, const char *fname, SMB_STRUCT_STAT *psbuf, uint32 access_mask)
129 {
130         if (!(access_mask & (FILE_READ_DATA|FILE_WRITE_DATA))) {
131                 return False;
132         }
133         access_mask &= (FILE_READ_DATA|FILE_WRITE_DATA);
134
135         /* some fast paths first */
136
137         DEBUG(10,("can_access_file: requesting 0x%x on file %s\n",
138                 (unsigned int)access_mask, fname ));
139
140         if (current_user.ut.uid == 0 || conn->admin_user) {
141                 /* I'm sorry sir, I didn't know you were root... */
142                 return True;
143         }
144
145         if (!VALID_STAT(*psbuf)) {
146                 /* Get the file permission mask and owners. */
147                 if(SMB_VFS_STAT(conn, fname, psbuf) != 0) {
148                         return False;
149                 }
150         }
151
152         /* Check primary owner access. */
153         if (current_user.ut.uid == psbuf->st_uid) {
154                 switch (access_mask) {
155                         case FILE_READ_DATA:
156                                 return (psbuf->st_mode & S_IRUSR) ? True : False;
157
158                         case FILE_WRITE_DATA:
159                                 return (psbuf->st_mode & S_IWUSR) ? True : False;
160
161                         default: /* FILE_READ_DATA|FILE_WRITE_DATA */
162
163                                 if ((psbuf->st_mode & (S_IWUSR|S_IRUSR)) == (S_IWUSR|S_IRUSR)) {
164                                         return True;
165                                 } else {
166                                         return False;
167                                 }
168                 }
169         }
170
171         /* now for ACL checks */
172
173         return can_access_file_acl(conn, fname, psbuf, access_mask);
174 }
175
176 /****************************************************************************
177  Userspace check for write access.
178  Note this doesn't take into account share write permissions.
179 ****************************************************************************/
180
181 bool can_write_to_file(connection_struct *conn, const char *fname, SMB_STRUCT_STAT *psbuf)
182 {
183         return can_access_file(conn, fname, psbuf, FILE_WRITE_DATA);
184 }
185