TOMOYO: Fix oops in tomoyo_mount_acl().
[linux-2.6.git] / security / tomoyo / mount.c
1 /*
2  * security/tomoyo/mount.c
3  *
4  * Copyright (C) 2005-2010  NTT DATA CORPORATION
5  */
6
7 #include <linux/slab.h>
8 #include "common.h"
9
10 /* Keywords for mount restrictions. */
11
12 /* Allow to call 'mount --bind /source_dir /dest_dir' */
13 #define TOMOYO_MOUNT_BIND_KEYWORD                        "--bind"
14 /* Allow to call 'mount --move /old_dir    /new_dir ' */
15 #define TOMOYO_MOUNT_MOVE_KEYWORD                        "--move"
16 /* Allow to call 'mount -o remount /dir             ' */
17 #define TOMOYO_MOUNT_REMOUNT_KEYWORD                     "--remount"
18 /* Allow to call 'mount --make-unbindable /dir'       */
19 #define TOMOYO_MOUNT_MAKE_UNBINDABLE_KEYWORD             "--make-unbindable"
20 /* Allow to call 'mount --make-private /dir'          */
21 #define TOMOYO_MOUNT_MAKE_PRIVATE_KEYWORD                "--make-private"
22 /* Allow to call 'mount --make-slave /dir'            */
23 #define TOMOYO_MOUNT_MAKE_SLAVE_KEYWORD                  "--make-slave"
24 /* Allow to call 'mount --make-shared /dir'           */
25 #define TOMOYO_MOUNT_MAKE_SHARED_KEYWORD                 "--make-shared"
26
27 /**
28  * tomoyo_audit_mount_log - Audit mount log.
29  *
30  * @r: Pointer to "struct tomoyo_request_info".
31  *
32  * Returns 0 on success, negative value otherwise.
33  */
34 static int tomoyo_audit_mount_log(struct tomoyo_request_info *r)
35 {
36         const char *dev = r->param.mount.dev->name;
37         const char *dir = r->param.mount.dir->name;
38         const char *type = r->param.mount.type->name;
39         const unsigned long flags = r->param.mount.flags;
40         if (r->granted)
41                 return 0;
42         if (!strcmp(type, TOMOYO_MOUNT_REMOUNT_KEYWORD))
43                 tomoyo_warn_log(r, "mount -o remount %s 0x%lX", dir, flags);
44         else if (!strcmp(type, TOMOYO_MOUNT_BIND_KEYWORD)
45                  || !strcmp(type, TOMOYO_MOUNT_MOVE_KEYWORD))
46                 tomoyo_warn_log(r, "mount %s %s %s 0x%lX", type, dev, dir,
47                                 flags);
48         else if (!strcmp(type, TOMOYO_MOUNT_MAKE_UNBINDABLE_KEYWORD) ||
49                  !strcmp(type, TOMOYO_MOUNT_MAKE_PRIVATE_KEYWORD) ||
50                  !strcmp(type, TOMOYO_MOUNT_MAKE_SLAVE_KEYWORD) ||
51                  !strcmp(type, TOMOYO_MOUNT_MAKE_SHARED_KEYWORD))
52                 tomoyo_warn_log(r, "mount %s %s 0x%lX", type, dir, flags);
53         else
54                 tomoyo_warn_log(r, "mount -t %s %s %s 0x%lX", type, dev, dir,
55                                 flags);
56         return tomoyo_supervisor(r,
57                                  TOMOYO_KEYWORD_ALLOW_MOUNT "%s %s %s 0x%lX\n",
58                                  tomoyo_pattern(r->param.mount.dev),
59                                  tomoyo_pattern(r->param.mount.dir), type,
60                                  flags);
61 }
62
63 static bool tomoyo_check_mount_acl(struct tomoyo_request_info *r,
64                                    const struct tomoyo_acl_info *ptr)
65 {
66         const struct tomoyo_mount_acl *acl =
67                 container_of(ptr, typeof(*acl), head);
68         return tomoyo_compare_number_union(r->param.mount.flags, &acl->flags) &&
69                 tomoyo_compare_name_union(r->param.mount.type, &acl->fs_type) &&
70                 tomoyo_compare_name_union(r->param.mount.dir, &acl->dir_name) &&
71                 (!r->param.mount.need_dev ||
72                  tomoyo_compare_name_union(r->param.mount.dev, &acl->dev_name));
73 }
74
75 /**
76  * tomoyo_mount_acl - Check permission for mount() operation.
77  *
78  * @r:        Pointer to "struct tomoyo_request_info".
79  * @dev_name: Name of device file.
80  * @dir:      Pointer to "struct path".
81  * @type:     Name of filesystem type.
82  * @flags:    Mount options.
83  *
84  * Returns 0 on success, negative value otherwise.
85  *
86  * Caller holds tomoyo_read_lock().
87  */
88 static int tomoyo_mount_acl(struct tomoyo_request_info *r, char *dev_name,
89                             struct path *dir, char *type, unsigned long flags)
90 {
91         struct path path;
92         struct file_system_type *fstype = NULL;
93         const char *requested_type = NULL;
94         const char *requested_dir_name = NULL;
95         const char *requested_dev_name = NULL;
96         struct tomoyo_path_info rtype;
97         struct tomoyo_path_info rdev;
98         struct tomoyo_path_info rdir;
99         int need_dev = 0;
100         int error = -ENOMEM;
101
102         /* Get fstype. */
103         requested_type = tomoyo_encode(type);
104         if (!requested_type)
105                 goto out;
106         rtype.name = requested_type;
107         tomoyo_fill_path_info(&rtype);
108
109         /* Get mount point. */
110         requested_dir_name = tomoyo_realpath_from_path(dir);
111         if (!requested_dir_name) {
112                 error = -ENOMEM;
113                 goto out;
114         }
115         rdir.name = requested_dir_name;
116         tomoyo_fill_path_info(&rdir);
117
118         /* Compare fs name. */
119         if (!strcmp(type, TOMOYO_MOUNT_REMOUNT_KEYWORD)) {
120                 /* dev_name is ignored. */
121         } else if (!strcmp(type, TOMOYO_MOUNT_MAKE_UNBINDABLE_KEYWORD) ||
122                    !strcmp(type, TOMOYO_MOUNT_MAKE_PRIVATE_KEYWORD) ||
123                    !strcmp(type, TOMOYO_MOUNT_MAKE_SLAVE_KEYWORD) ||
124                    !strcmp(type, TOMOYO_MOUNT_MAKE_SHARED_KEYWORD)) {
125                 /* dev_name is ignored. */
126         } else if (!strcmp(type, TOMOYO_MOUNT_BIND_KEYWORD) ||
127                    !strcmp(type, TOMOYO_MOUNT_MOVE_KEYWORD)) {
128                 need_dev = -1; /* dev_name is a directory */
129         } else {
130                 fstype = get_fs_type(type);
131                 if (!fstype) {
132                         error = -ENODEV;
133                         goto out;
134                 }
135                 if (fstype->fs_flags & FS_REQUIRES_DEV)
136                         /* dev_name is a block device file. */
137                         need_dev = 1;
138         }
139         if (need_dev) {
140                 /* Get mount point or device file. */
141                 if (!dev_name || kern_path(dev_name, LOOKUP_FOLLOW, &path)) {
142                         error = -ENOENT;
143                         goto out;
144                 }
145                 requested_dev_name = tomoyo_realpath_from_path(&path);
146                 path_put(&path);
147                 if (!requested_dev_name) {
148                         error = -ENOENT;
149                         goto out;
150                 }
151         } else {
152                 /* Map dev_name to "<NULL>" if no dev_name given. */
153                 if (!dev_name)
154                         dev_name = "<NULL>";
155                 requested_dev_name = tomoyo_encode(dev_name);
156                 if (!requested_dev_name) {
157                         error = -ENOMEM;
158                         goto out;
159                 }
160         }
161         rdev.name = requested_dev_name;
162         tomoyo_fill_path_info(&rdev);
163         r->param_type = TOMOYO_TYPE_MOUNT_ACL;
164         r->param.mount.need_dev = need_dev;
165         r->param.mount.dev = &rdev;
166         r->param.mount.dir = &rdir;
167         r->param.mount.type = &rtype;
168         r->param.mount.flags = flags;
169         do {
170                 tomoyo_check_acl(r, tomoyo_check_mount_acl);
171                 error = tomoyo_audit_mount_log(r);
172         } while (error == TOMOYO_RETRY_REQUEST);
173  out:
174         kfree(requested_dev_name);
175         kfree(requested_dir_name);
176         if (fstype)
177                 put_filesystem(fstype);
178         kfree(requested_type);
179         return error;
180 }
181
182 /**
183  * tomoyo_mount_permission - Check permission for mount() operation.
184  *
185  * @dev_name:  Name of device file.
186  * @path:      Pointer to "struct path".
187  * @type:      Name of filesystem type. May be NULL.
188  * @flags:     Mount options.
189  * @data_page: Optional data. May be NULL.
190  *
191  * Returns 0 on success, negative value otherwise.
192  */
193 int tomoyo_mount_permission(char *dev_name, struct path *path, char *type,
194                             unsigned long flags, void *data_page)
195 {
196         struct tomoyo_request_info r;
197         int error;
198         int idx;
199
200         if (tomoyo_init_request_info(&r, NULL, TOMOYO_MAC_FILE_MOUNT)
201             == TOMOYO_CONFIG_DISABLED)
202                 return 0;
203         if ((flags & MS_MGC_MSK) == MS_MGC_VAL)
204                 flags &= ~MS_MGC_MSK;
205         if (flags & MS_REMOUNT) {
206                 type = TOMOYO_MOUNT_REMOUNT_KEYWORD;
207                 flags &= ~MS_REMOUNT;
208         }
209         if (flags & MS_MOVE) {
210                 type = TOMOYO_MOUNT_MOVE_KEYWORD;
211                 flags &= ~MS_MOVE;
212         }
213         if (flags & MS_BIND) {
214                 type = TOMOYO_MOUNT_BIND_KEYWORD;
215                 flags &= ~MS_BIND;
216         }
217         if (flags & MS_UNBINDABLE) {
218                 type = TOMOYO_MOUNT_MAKE_UNBINDABLE_KEYWORD;
219                 flags &= ~MS_UNBINDABLE;
220         }
221         if (flags & MS_PRIVATE) {
222                 type = TOMOYO_MOUNT_MAKE_PRIVATE_KEYWORD;
223                 flags &= ~MS_PRIVATE;
224         }
225         if (flags & MS_SLAVE) {
226                 type = TOMOYO_MOUNT_MAKE_SLAVE_KEYWORD;
227                 flags &= ~MS_SLAVE;
228         }
229         if (flags & MS_SHARED) {
230                 type = TOMOYO_MOUNT_MAKE_SHARED_KEYWORD;
231                 flags &= ~MS_SHARED;
232         }
233         if (!type)
234                 type = "<NULL>";
235         idx = tomoyo_read_lock();
236         error = tomoyo_mount_acl(&r, dev_name, path, type, flags);
237         tomoyo_read_unlock(idx);
238         return error;
239 }
240
241 static bool tomoyo_same_mount_acl(const struct tomoyo_acl_info *a,
242                                   const struct tomoyo_acl_info *b)
243 {
244         const struct tomoyo_mount_acl *p1 = container_of(a, typeof(*p1), head);
245         const struct tomoyo_mount_acl *p2 = container_of(b, typeof(*p2), head);
246         return tomoyo_same_acl_head(&p1->head, &p2->head) &&
247                 tomoyo_same_name_union(&p1->dev_name, &p2->dev_name) &&
248                 tomoyo_same_name_union(&p1->dir_name, &p2->dir_name) &&
249                 tomoyo_same_name_union(&p1->fs_type, &p2->fs_type) &&
250                 tomoyo_same_number_union(&p1->flags, &p2->flags);
251 }
252
253 /**
254  * tomoyo_write_mount - Write "struct tomoyo_mount_acl" list.
255  *
256  * @data:      String to parse.
257  * @domain:    Pointer to "struct tomoyo_domain_info".
258  * @is_delete: True if it is a delete request.
259  *
260  * Returns 0 on success, negative value otherwise.
261  *
262  * Caller holds tomoyo_read_lock().
263  */
264 int tomoyo_write_mount(char *data, struct tomoyo_domain_info *domain,
265                        const bool is_delete)
266 {
267         struct tomoyo_mount_acl e = { .head.type = TOMOYO_TYPE_MOUNT_ACL };
268         int error = is_delete ? -ENOENT : -ENOMEM;
269         char *w[4];
270         if (!tomoyo_tokenize(data, w, sizeof(w)) || !w[3][0])
271                 return -EINVAL;
272         if (!tomoyo_parse_name_union(w[0], &e.dev_name) ||
273             !tomoyo_parse_name_union(w[1], &e.dir_name) ||
274             !tomoyo_parse_name_union(w[2], &e.fs_type) ||
275             !tomoyo_parse_number_union(w[3], &e.flags))
276                 goto out;
277         error = tomoyo_update_domain(&e.head, sizeof(e), is_delete, domain,
278                                      tomoyo_same_mount_acl, NULL);
279  out:
280         tomoyo_put_name_union(&e.dev_name);
281         tomoyo_put_name_union(&e.dir_name);
282         tomoyo_put_name_union(&e.fs_type);
283         tomoyo_put_number_union(&e.flags);
284         return error;
285 }