mount.c revision 75093152a97ee0ec281895b4f6229ff3c481fd64 
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 */
34static 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_file_pattern(r->param.mount.dev),
59				 tomoyo_file_pattern(r->param.mount.dir), type,
60				 flags);
61}
62
63static bool tomoyo_check_mount_acl(const 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_acl2 - 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 */
88static int tomoyo_mount_acl2(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 (kern_path(dev_name, LOOKUP_FOLLOW, &path)) {
142			error = -ENOENT;
143			goto out;
144		}
145		requested_dev_name = tomoyo_realpath_from_path(&path);
146		if (!requested_dev_name) {
147			error = -ENOENT;
148			goto out;
149		}
150	} else {
151		/* Map dev_name to "<NULL>" if no dev_name given. */
152		if (!dev_name)
153			dev_name = "<NULL>";
154		requested_dev_name = tomoyo_encode(dev_name);
155		if (!requested_dev_name) {
156			error = -ENOMEM;
157			goto out;
158		}
159	}
160	rdev.name = requested_dev_name;
161	tomoyo_fill_path_info(&rdev);
162	r->param_type = TOMOYO_TYPE_MOUNT_ACL;
163	r->param.mount.need_dev = need_dev;
164	r->param.mount.dev = &rdev;
165	r->param.mount.dir = &rdir;
166	r->param.mount.type = &rtype;
167	r->param.mount.flags = flags;
168	do {
169		tomoyo_check_acl(r, tomoyo_check_mount_acl);
170		error = tomoyo_audit_mount_log(r);
171	} while (error == TOMOYO_RETRY_REQUEST);
172 out:
173	kfree(requested_dev_name);
174	kfree(requested_dir_name);
175	if (fstype)
176		put_filesystem(fstype);
177	kfree(requested_type);
178	return error;
179}
180
181/**
182 * tomoyo_mount_acl - Check permission for mount() operation.
183 *
184 * @r:        Pointer to "struct tomoyo_request_info".
185 * @dev_name: Name of device file.
186 * @dir:      Pointer to "struct path".
187 * @type:     Name of filesystem type.
188 * @flags:    Mount options.
189 *
190 * Returns 0 on success, negative value otherwise.
191 *
192 * Caller holds tomoyo_read_lock().
193 */
194static int tomoyo_mount_acl(struct tomoyo_request_info *r, char *dev_name,
195			    struct path *dir, char *type, unsigned long flags)
196{
197	int error;
198	error = -EPERM;
199	if ((flags & MS_MGC_MSK) == MS_MGC_VAL)
200		flags &= ~MS_MGC_MSK;
201	switch (flags & (MS_REMOUNT | MS_MOVE | MS_BIND)) {
202	case MS_REMOUNT:
203	case MS_MOVE:
204	case MS_BIND:
205	case 0:
206		break;
207	default:
208		printk(KERN_WARNING "ERROR: "
209		       "%s%s%sare given for single mount operation.\n",
210		       flags & MS_REMOUNT ? "'remount' " : "",
211		       flags & MS_MOVE    ? "'move' " : "",
212		       flags & MS_BIND    ? "'bind' " : "");
213		return -EINVAL;
214	}
215	switch (flags & (MS_UNBINDABLE | MS_PRIVATE | MS_SLAVE | MS_SHARED)) {
216	case MS_UNBINDABLE:
217	case MS_PRIVATE:
218	case MS_SLAVE:
219	case MS_SHARED:
220	case 0:
221		break;
222	default:
223		printk(KERN_WARNING "ERROR: "
224		       "%s%s%s%sare given for single mount operation.\n",
225		       flags & MS_UNBINDABLE ? "'unbindable' " : "",
226		       flags & MS_PRIVATE    ? "'private' " : "",
227		       flags & MS_SLAVE      ? "'slave' " : "",
228		       flags & MS_SHARED     ? "'shared' " : "");
229		return -EINVAL;
230	}
231	if (flags & MS_REMOUNT)
232		error = tomoyo_mount_acl(r, dev_name, dir,
233				      TOMOYO_MOUNT_REMOUNT_KEYWORD,
234				      flags & ~MS_REMOUNT);
235	else if (flags & MS_MOVE)
236		error = tomoyo_mount_acl(r, dev_name, dir,
237				      TOMOYO_MOUNT_MOVE_KEYWORD,
238				      flags & ~MS_MOVE);
239	else if (flags & MS_BIND)
240		error = tomoyo_mount_acl(r, dev_name, dir,
241				      TOMOYO_MOUNT_BIND_KEYWORD,
242				      flags & ~MS_BIND);
243	else if (flags & MS_UNBINDABLE)
244		error = tomoyo_mount_acl(r, dev_name, dir,
245				      TOMOYO_MOUNT_MAKE_UNBINDABLE_KEYWORD,
246				      flags & ~MS_UNBINDABLE);
247	else if (flags & MS_PRIVATE)
248		error = tomoyo_mount_acl(r, dev_name, dir,
249				      TOMOYO_MOUNT_MAKE_PRIVATE_KEYWORD,
250				      flags & ~MS_PRIVATE);
251	else if (flags & MS_SLAVE)
252		error = tomoyo_mount_acl(r, dev_name, dir,
253				      TOMOYO_MOUNT_MAKE_SLAVE_KEYWORD,
254				      flags & ~MS_SLAVE);
255	else if (flags & MS_SHARED)
256		error = tomoyo_mount_acl(r, dev_name, dir,
257				      TOMOYO_MOUNT_MAKE_SHARED_KEYWORD,
258				      flags & ~MS_SHARED);
259	else
260		do {
261			error = tomoyo_mount_acl2(r, dev_name, dir, type,
262						  flags);
263		} while (error == TOMOYO_RETRY_REQUEST);
264	if (r->mode != TOMOYO_CONFIG_ENFORCING)
265		error = 0;
266	return error;
267}
268
269/**
270 * tomoyo_mount_permission - Check permission for mount() operation.
271 *
272 * @dev_name:  Name of device file.
273 * @path:      Pointer to "struct path".
274 * @type:      Name of filesystem type. May be NULL.
275 * @flags:     Mount options.
276 * @data_page: Optional data. May be NULL.
277 *
278 * Returns 0 on success, negative value otherwise.
279 */
280int tomoyo_mount_permission(char *dev_name, struct path *path, char *type,
281			    unsigned long flags, void *data_page)
282{
283	struct tomoyo_request_info r;
284	int error;
285	int idx;
286
287	if (tomoyo_init_request_info(&r, NULL, TOMOYO_MAC_FILE_MOUNT)
288	    == TOMOYO_CONFIG_DISABLED)
289		return 0;
290	if (!type)
291		type = "<NULL>";
292	idx = tomoyo_read_lock();
293	error = tomoyo_mount_acl(&r, dev_name, path, type, flags);
294	tomoyo_read_unlock(idx);
295	return error;
296}
297
298static bool tomoyo_same_mount_acl(const struct tomoyo_acl_info *a,
299				  const struct tomoyo_acl_info *b)
300{
301	const struct tomoyo_mount_acl *p1 = container_of(a, typeof(*p1), head);
302	const struct tomoyo_mount_acl *p2 = container_of(b, typeof(*p2), head);
303	return tomoyo_same_acl_head(&p1->head, &p2->head) &&
304		tomoyo_same_name_union(&p1->dev_name, &p2->dev_name) &&
305		tomoyo_same_name_union(&p1->dir_name, &p2->dir_name) &&
306		tomoyo_same_name_union(&p1->fs_type, &p2->fs_type) &&
307		tomoyo_same_number_union(&p1->flags, &p2->flags);
308}
309
310/**
311 * tomoyo_write_mount_policy - Write "struct tomoyo_mount_acl" list.
312 *
313 * @data:      String to parse.
314 * @domain:    Pointer to "struct tomoyo_domain_info".
315 * @is_delete: True if it is a delete request.
316 *
317 * Returns 0 on success, negative value otherwise.
318 *
319 * Caller holds tomoyo_read_lock().
320 */
321int tomoyo_write_mount_policy(char *data, struct tomoyo_domain_info *domain,
322			      const bool is_delete)
323{
324	struct tomoyo_mount_acl e = { .head.type = TOMOYO_TYPE_MOUNT_ACL };
325	int error = is_delete ? -ENOENT : -ENOMEM;
326	char *w[4];
327	if (!tomoyo_tokenize(data, w, sizeof(w)) || !w[3][0])
328		return -EINVAL;
329	if (!tomoyo_parse_name_union(w[0], &e.dev_name) ||
330	    !tomoyo_parse_name_union(w[1], &e.dir_name) ||
331	    !tomoyo_parse_name_union(w[2], &e.fs_type) ||
332	    !tomoyo_parse_number_union(w[3], &e.flags))
333		goto out;
334	error = tomoyo_update_domain(&e.head, sizeof(e), is_delete, domain,
335				     tomoyo_same_mount_acl, NULL);
336 out:
337	tomoyo_put_name_union(&e.dev_name);
338	tomoyo_put_name_union(&e.dir_name);
339	tomoyo_put_name_union(&e.fs_type);
340	tomoyo_put_number_union(&e.flags);
341	return error;
342}
343