aboutsummaryrefslogtreecommitdiffstats
path: root/security/tomoyo/realpath.c
blob: 3ceb1724c92d4b82df969de1a7baa1fdc7a839c1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
/*
 * security/tomoyo/realpath.c
 *
 * Get the canonicalized absolute pathnames. The basis for TOMOYO.
 *
 * Copyright (C) 2005-2009  NTT DATA CORPORATION
 *
 * Version: 2.2.0   2009/04/01
 *
 */

#include <linux/types.h>
#include <linux/mount.h>
#include <linux/mnt_namespace.h>
#include <linux/fs_struct.h>
#include <linux/hash.h>
#include <linux/magic.h>
#include <linux/slab.h>
#include "common.h"

/**
 * tomoyo_encode: Convert binary string to ascii string.
 *
 * @buffer:  Buffer for ASCII string.
 * @buflen:  Size of @buffer.
 * @str:     Binary string.
 *
 * Returns 0 on success, -ENOMEM otherwise.
 */
int tomoyo_encode(char *buffer, int buflen, const char *str)
{
	while (1) {
		const unsigned char c = *(unsigned char *) str++;

		if (tomoyo_is_valid(c)) {
			if (--buflen <= 0)
				break;
			*buffer++ = (char) c;
			if (c != '\\')
				continue;
			if (--buflen <= 0)
				break;
			*buffer++ = (char) c;
			continue;
		}
		if (!c) {
			if (--buflen <= 0)
				break;
			*buffer = '\0';
			return 0;
		}
		buflen -= 4;
		if (buflen <= 0)
			break;
		*buffer++ = '\\';
		*buffer++ = (c >> 6) + '0';
		*buffer++ = ((c >> 3) & 7) + '0';
		*buffer++ = (c & 7) + '0';
	}
	return -ENOMEM;
}

/**
 * tomoyo_realpath_from_path2 - Returns realpath(3) of the given dentry but ignores chroot'ed root.
 *
 * @path:        Pointer to "struct path".
 * @newname:     Pointer to buffer to return value in.
 * @newname_len: Size of @newname.
 *
 * Returns 0 on success, negative value otherwise.
 *
 * If dentry is a directory, trailing '/' is appended.
 * Characters out of 0x20 < c < 0x7F range are converted to
 * \ooo style octal string.
 * Character \ is converted to \\ string.
 */
int tomoyo_realpath_from_path2(struct path *path, char *newname,
			       int newname_len)
{
	int error = -ENOMEM;
	struct dentry *dentry = path->dentry;
	char *sp;

	if (!dentry || !path->mnt || !newname || newname_len <= 2048)
		return -EINVAL;
	if (dentry->d_op && dentry->d_op->d_dname) {
		/* For "socket:[\$]" and "pipe:[\$]". */
		static const int offset = 1536;
		sp = dentry->d_op->d_dname(dentry, newname + offset,
					   newname_len - offset);
	} else {
		struct path ns_root = {.mnt = NULL, .dentry = NULL};

		spin_lock(&dcache_lock);
		/* go to whatever namespace root we are under */
		sp = __d_path(path, &ns_root, newname, newname_len);
		spin_unlock(&dcache_lock);
		/* Prepend "/proc" prefix if using internal proc vfs mount. */
		if (!IS_ERR(sp) && (path->mnt->mnt_flags & MNT_INTERNAL) &&
		    (path->mnt->mnt_sb->s_magic == PROC_SUPER_MAGIC)) {
			sp -= 5;
			if (sp >= newname)
				memcpy(sp, "/proc", 5);
			else
				sp = ERR_PTR(-ENOMEM);
		}
	}
	if (IS_ERR(sp))
		error = PTR_ERR(sp);
	else
		error = tomoyo_encode(newname, sp - newname, sp);
	/* Append trailing '/' if dentry is a directory. */
	if (!error && dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)
	    && *newname) {
		sp = newname + strlen(newname);
		if (*(sp - 1) != '/') {
			if (sp < newname + newname_len - 4) {
				*sp++ = '/';
				*sp = '\0';
			} else {
				error = -ENOMEM;
			}
		}
	}
	if (error)
		printk(KERN_WARNING "tomoyo_realpath: Pathname too long.\n");
	return error;
}

/**
 * tomoyo_realpath_from_path - Returns realpath(3) of the given pathname but ignores chroot'ed root.
 *
 * @path: Pointer to "struct path".
 *
 * Returns the realpath of the given @path on success, NULL otherwise.
 *
 * These functions use kzalloc(), so the caller must call kfree()
 * if these functions didn't return NULL.
 */
char *tomoyo_realpath_from_path(struct path *path)
{
	char *buf = kzalloc(sizeof(struct tomoyo_page_buffer), GFP_NOFS);

	BUILD_BUG_ON(sizeof(struct tomoyo_page_buffer)
		     <= TOMOYO_MAX_PATHNAME_LEN - 1);
	if (!buf)
		return NULL;
	if (tomoyo_realpath_from_path2(path, buf,
				       TOMOYO_MAX_PATHNAME_LEN - 1) == 0)
		return buf;
	kfree(buf);
	return NULL;
}

/**
 * tomoyo_realpath - Get realpath of a pathname.
 *
 * @pathname: The pathname to solve.
 *
 * Returns the realpath of @pathname on success, NULL otherwise.
 */
char *tomoyo_realpath(const char *pathname)
{
	struct path path;

	if (pathname && kern_path(pathname, LOOKUP_FOLLOW, &path) == 0) {
		char *buf = tomoyo_realpath_from_path(&path);
		path_put(&path);
		return buf;
	}
	return NULL;
}

/**
 * tomoyo_realpath_nofollow - Get realpath of a pathname.
 *
 * @pathname: The pathname to solve.
 *
 * Returns the realpath of @pathname on success, NULL otherwise.
 */
char *tomoyo_realpath_nofollow(const char *pathname)
{
	struct path path;

	if (pathname && kern_path(pathname, 0, &path) == 0) {
		char *buf = tomoyo_realpath_from_path(&path);
		path_put(&path);
		return buf;
	}
	return NULL;
}

/* Memory allocated for non-string data. */
static atomic_t tomoyo_policy_memory_size;
/* Quota for holding policy. */
static unsigned int tomoyo_quota_for_policy;

/**
 * tomoyo_memory_ok - Check memory quota.
 *
 * @ptr: Pointer to allocated memory.
 *
 * Returns true on success, false otherwise.
 *
 * Caller holds tomoyo_policy_lock.
 * Memory pointed by @ptr will be zeroed on success.
 */
bool tomoyo_memory_ok(void *ptr)
{
	int allocated_len = ptr ? ksize(ptr) : 0;
	atomic_add(allocated_len, &tomoyo_policy_memory_size);
	if (ptr && (!tomoyo_quota_for_policy ||
		    atomic_read(&tomoyo_policy_memory_size)
		    <= tomoyo_quota_for_policy)) {
		memset(ptr, 0, allocated_len);
		return true;
	}
	printk(KERN_WARNING "ERROR: Out of memory "
	       "for tomoyo_alloc_element().\n");
	if (!tomoyo_policy_loaded)
		panic("MAC Initialization failed.\n");
	return false;
}

/**
 * tomoyo_commit_ok - Check memory quota.
 *
 * @data:   Data to copy from.
 * @size:   Size in byte.
 *
 * Returns pointer to allocated memory on success, NULL otherwise.
 */
void *tomoyo_commit_ok(void *data, const unsigned int size)
{
	void *ptr = kzalloc(size, GFP_NOFS);
	if (tomoyo_memory_ok(ptr)) {
		memmove(ptr, data, size);
		memset(data, 0, size);
		return ptr;
	}
	return NULL;
}

/**
 * tomoyo_memory_free - Free memory for elements.
 *
 * @ptr:  Pointer to allocated memory.
 */
void tomoyo_memory_free(void *ptr)
{
	atomic_sub(ksize(ptr), &tomoyo_policy_memory_size);
	kfree(ptr);
}

/*
 * tomoyo_name_list is used for holding string data used by TOMOYO.
 * Since same string data is likely used for multiple times (e.g.
 * "/lib/libc-2.5.so"), TOMOYO shares string data in the form of
 * "const struct tomoyo_path_info *".
 */
struct list_head tomoyo_name_list[TOMOYO_MAX_HASH];

/**
 * tomoyo_get_name - Allocate permanent memory for string data.
 *
 * @name: The string to store into the permernent memory.
 *
 * Returns pointer to "struct tomoyo_path_info" on success, NULL otherwise.
 */
const struct tomoyo_path_info *tomoyo_get_name(const char *name)
{
	struct tomoyo_name_entry *ptr;
	unsigned int hash;
	int len;
	int allocated_len;
	struct list_head *head;

	if (!name)
		return NULL;
	len = strlen(name) + 1;
	hash = full_name_hash((const unsigned char *) name, len - 1);
	head = &tomoyo_name_list[hash_long(hash, TOMOYO_HASH_BITS)];
	if (mutex_lock_interruptible(&tomoyo_policy_lock))
		return NULL;
	list_for_each_entry(ptr, head, list) {
		if (hash != ptr->entry.hash || strcmp(name, ptr->entry.name))
			continue;
		atomic_inc(&ptr->users);
		goto out;
	}
	ptr = kzalloc(sizeof(*ptr) + len, GFP_NOFS);
	allocated_len = ptr ? ksize(ptr) : 0;
	if (!ptr || (tomoyo_quota_for_policy &&
		     atomic_read(&tomoyo_policy_memory_size) + allocated_len
		     > tomoyo_quota_for_policy)) {
		kfree(ptr);
		printk(KERN_WARNING "ERROR: Out of memory "
		       "for tomoyo_get_name().\n");
		if (!tomoyo_policy_loaded)
			panic("MAC Initialization failed.\n");
		ptr = NULL;
		goto out;
	}
	atomic_add(allocated_len, &tomoyo_policy_memory_size);
	ptr->entry.name = ((char *) ptr) + sizeof(*ptr);
	memmove((char *) ptr->entry.name, name, len);
	atomic_set(&ptr->users, 1);
	tomoyo_fill_path_info(&ptr->entry);
	list_add_tail(&ptr->list, head);
 out:
	mutex_unlock(&tomoyo_policy_lock);
	return ptr ? &ptr->entry : NULL;
}

/**
 * tomoyo_realpath_init - Initialize realpath related code.
 */
void __init tomoyo_realpath_init(void)
{
	int i;

	BUILD_BUG_ON(TOMOYO_MAX_PATHNAME_LEN > PATH_MAX);
	for (i = 0; i < TOMOYO_MAX_HASH; i++)
		INIT_LIST_HEAD(&tomoyo_name_list[i]);
	INIT_LIST_HEAD(&tomoyo_kernel_domain.acl_info_list);
	tomoyo_kernel_domain.domainname = tomoyo_get_name(TOMOYO_ROOT_NAME);
	/*
	 * tomoyo_read_lock() is not needed because this function is
	 * called before the first "delete" request.
	 */
	list_add_tail_rcu(&tomoyo_kernel_domain.list, &tomoyo_domain_list);
	if (tomoyo_find_domain(TOMOYO_ROOT_NAME) != &tomoyo_kernel_domain)
		panic("Can't register tomoyo_kernel_domain");
}

unsigned int tomoyo_quota_for_query;
unsigned int tomoyo_query_memory_size;

/**
 * tomoyo_read_memory_counter - Check for memory usage in bytes.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 *
 * Returns memory usage.
 */
int tomoyo_read_memory_counter(struct tomoyo_io_buffer *head)
{
	if (!head->read_eof) {
		const unsigned int policy
			= atomic_read(&tomoyo_policy_memory_size);
		const unsigned int query = tomoyo_query_memory_size;
		char buffer[64];

		memset(buffer, 0, sizeof(buffer));
		if (tomoyo_quota_for_policy)
			snprintf(buffer, sizeof(buffer) - 1,
				 "   (Quota: %10u)",
				 tomoyo_quota_for_policy);
		else
			buffer[0] = '\0';
		tomoyo_io_printf(head, "Policy:       %10u%s\n", policy,
				 buffer);
		if (tomoyo_quota_for_query)
			snprintf(buffer, sizeof(buffer) - 1,
				 "   (Quota: %10u)",
				 tomoyo_quota_for_query);
		else
			buffer[0] = '\0';
		tomoyo_io_printf(head, "Query lists:  %10u%s\n", query,
				 buffer);
		tomoyo_io_printf(head, "Total:        %10u\n", policy + query);
		head->read_eof = true;
	}
	return 0;
}

/**
 * tomoyo_write_memory_quota - Set memory quota.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 *
 * Returns 0.
 */
int tomoyo_write_memory_quota(struct tomoyo_io_buffer *head)
{
	char *data = head->write_buf;
	unsigned int size;

	if (sscanf(data, "Policy: %u", &size) == 1)
		tomoyo_quota_for_policy = size;
	else if (sscanf(data, "Query lists: %u", &size) == 1)
		tomoyo_quota_for_query = size;
	return 0;
}