2 * security/tomoyo/realpath.c
4 * Get the canonicalized absolute pathnames. The basis for TOMOYO.
6 * Copyright (C) 2005-2009 NTT DATA CORPORATION
8 * Version: 2.2.0 2009/04/01
12 #include <linux/types.h>
13 #include <linux/mount.h>
14 #include <linux/mnt_namespace.h>
15 #include <linux/fs_struct.h>
16 #include <linux/hash.h>
17 #include <linux/magic.h>
23 * tomoyo_encode: Convert binary string to ascii string.
25 * @buffer: Buffer for ASCII string.
26 * @buflen: Size of @buffer.
27 * @str: Binary string.
29 * Returns 0 on success, -ENOMEM otherwise.
31 int tomoyo_encode(char *buffer, int buflen, const char *str)
34 const unsigned char c = *(unsigned char *) str++;
36 if (tomoyo_is_valid(c)) {
57 *buffer++ = (c >> 6) + '0';
58 *buffer++ = ((c >> 3) & 7) + '0';
59 *buffer++ = (c & 7) + '0';
65 * tomoyo_realpath_from_path2 - Returns realpath(3) of the given dentry but ignores chroot'ed root.
67 * @path: Pointer to "struct path".
68 * @newname: Pointer to buffer to return value in.
69 * @newname_len: Size of @newname.
71 * Returns 0 on success, negative value otherwise.
73 * If dentry is a directory, trailing '/' is appended.
74 * Characters out of 0x20 < c < 0x7F range are converted to
75 * \ooo style octal string.
76 * Character \ is converted to \\ string.
78 int tomoyo_realpath_from_path2(struct path *path, char *newname,
82 struct dentry *dentry = path->dentry;
85 if (!dentry || !path->mnt || !newname || newname_len <= 2048)
87 if (dentry->d_op && dentry->d_op->d_dname) {
88 /* For "socket:[\$]" and "pipe:[\$]". */
89 static const int offset = 1536;
90 sp = dentry->d_op->d_dname(dentry, newname + offset,
91 newname_len - offset);
93 /* Taken from d_namespace_path(). */
95 struct path ns_root = { };
98 read_lock(¤t->fs->lock);
99 root = current->fs->root;
101 read_unlock(¤t->fs->lock);
102 spin_lock(&vfsmount_lock);
103 if (root.mnt && root.mnt->mnt_ns)
104 ns_root.mnt = mntget(root.mnt->mnt_ns->root);
106 ns_root.dentry = dget(ns_root.mnt->mnt_root);
107 spin_unlock(&vfsmount_lock);
108 spin_lock(&dcache_lock);
110 sp = __d_path(path, &tmp, newname, newname_len);
111 spin_unlock(&dcache_lock);
114 /* Prepend "/proc" prefix if using internal proc vfs mount. */
115 if (!IS_ERR(sp) && (path->mnt->mnt_parent == path->mnt) &&
116 (path->mnt->mnt_sb->s_magic == PROC_SUPER_MAGIC)) {
119 memcpy(sp, "/proc", 5);
121 sp = ERR_PTR(-ENOMEM);
127 error = tomoyo_encode(newname, sp - newname, sp);
128 /* Append trailing '/' if dentry is a directory. */
129 if (!error && dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)
131 sp = newname + strlen(newname);
132 if (*(sp - 1) != '/') {
133 if (sp < newname + newname_len - 4) {
142 printk(KERN_WARNING "tomoyo_realpath: Pathname too long.\n");
147 * tomoyo_realpath_from_path - Returns realpath(3) of the given pathname but ignores chroot'ed root.
149 * @path: Pointer to "struct path".
151 * Returns the realpath of the given @path on success, NULL otherwise.
153 * These functions use tomoyo_alloc(), so the caller must call tomoyo_free()
154 * if these functions didn't return NULL.
156 char *tomoyo_realpath_from_path(struct path *path)
158 char *buf = tomoyo_alloc(sizeof(struct tomoyo_page_buffer));
160 BUILD_BUG_ON(sizeof(struct tomoyo_page_buffer)
161 <= TOMOYO_MAX_PATHNAME_LEN - 1);
164 if (tomoyo_realpath_from_path2(path, buf,
165 TOMOYO_MAX_PATHNAME_LEN - 1) == 0)
172 * tomoyo_realpath - Get realpath of a pathname.
174 * @pathname: The pathname to solve.
176 * Returns the realpath of @pathname on success, NULL otherwise.
178 char *tomoyo_realpath(const char *pathname)
182 if (pathname && kern_path(pathname, LOOKUP_FOLLOW, &path) == 0) {
183 char *buf = tomoyo_realpath_from_path(&path);
191 * tomoyo_realpath_nofollow - Get realpath of a pathname.
193 * @pathname: The pathname to solve.
195 * Returns the realpath of @pathname on success, NULL otherwise.
197 char *tomoyo_realpath_nofollow(const char *pathname)
201 if (pathname && kern_path(pathname, 0, &path) == 0) {
202 char *buf = tomoyo_realpath_from_path(&path);
209 /* Memory allocated for non-string data. */
210 static unsigned int tomoyo_allocated_memory_for_elements;
211 /* Quota for holding non-string data. */
212 static unsigned int tomoyo_quota_for_elements;
215 * tomoyo_alloc_element - Allocate permanent memory for structures.
217 * @size: Size in bytes.
219 * Returns pointer to allocated memory on success, NULL otherwise.
221 * Memory has to be zeroed.
222 * The RAM is chunked, so NEVER try to kfree() the returned pointer.
224 void *tomoyo_alloc_element(const unsigned int size)
227 static DEFINE_MUTEX(lock);
228 static unsigned int buf_used_len = PATH_MAX;
230 /*Assumes sizeof(void *) >= sizeof(long) is true. */
231 const unsigned int word_aligned_size
232 = roundup(size, max(sizeof(void *), sizeof(long)));
233 if (word_aligned_size > PATH_MAX)
236 if (buf_used_len + word_aligned_size > PATH_MAX) {
237 if (!tomoyo_quota_for_elements ||
238 tomoyo_allocated_memory_for_elements
239 + PATH_MAX <= tomoyo_quota_for_elements)
240 ptr = kzalloc(PATH_MAX, GFP_KERNEL);
242 printk(KERN_WARNING "ERROR: Out of memory "
243 "for tomoyo_alloc_element().\n");
244 if (!tomoyo_policy_loaded)
245 panic("MAC Initialization failed.\n");
248 tomoyo_allocated_memory_for_elements += PATH_MAX;
249 buf_used_len = word_aligned_size;
252 } else if (word_aligned_size) {
254 ptr = buf + buf_used_len;
255 buf_used_len += word_aligned_size;
256 for (i = 0; i < word_aligned_size; i++) {
259 printk(KERN_ERR "WARNING: Reserved memory was tainted! "
260 "The system might go wrong.\n");
268 /* Memory allocated for string data in bytes. */
269 static unsigned int tomoyo_allocated_memory_for_savename;
270 /* Quota for holding string data in bytes. */
271 static unsigned int tomoyo_quota_for_savename;
274 * TOMOYO uses this hash only when appending a string into the string
275 * table. Frequency of appending strings is very low. So we don't need
276 * large (e.g. 64k) hash size. 256 will be sufficient.
278 #define TOMOYO_HASH_BITS 8
279 #define TOMOYO_MAX_HASH (1u<<TOMOYO_HASH_BITS)
282 * tomoyo_name_entry is a structure which is used for linking
283 * "struct tomoyo_path_info" into tomoyo_name_list .
285 * Since tomoyo_name_list manages a list of strings which are shared by
286 * multiple processes (whereas "struct tomoyo_path_info" inside
287 * "struct tomoyo_path_info_with_data" is not shared), a reference counter will
288 * be added to "struct tomoyo_name_entry" rather than "struct tomoyo_path_info"
289 * when TOMOYO starts supporting garbage collector.
291 struct tomoyo_name_entry {
292 struct list_head list;
293 struct tomoyo_path_info entry;
296 /* Structure for available memory region. */
297 struct tomoyo_free_memory_block_list {
298 struct list_head list;
299 char *ptr; /* Pointer to a free area. */
300 int len; /* Length of the area. */
304 * tomoyo_name_list is used for holding string data used by TOMOYO.
305 * Since same string data is likely used for multiple times (e.g.
306 * "/lib/libc-2.5.so"), TOMOYO shares string data in the form of
307 * "const struct tomoyo_path_info *".
309 static struct list_head tomoyo_name_list[TOMOYO_MAX_HASH];
312 * tomoyo_save_name - Allocate permanent memory for string data.
314 * @name: The string to store into the permernent memory.
316 * Returns pointer to "struct tomoyo_path_info" on success, NULL otherwise.
318 * The RAM is shared, so NEVER try to modify or kfree() the returned name.
320 const struct tomoyo_path_info *tomoyo_save_name(const char *name)
322 static LIST_HEAD(fmb_list);
323 static DEFINE_MUTEX(lock);
324 struct tomoyo_name_entry *ptr;
326 /* fmb contains available size in bytes.
327 fmb is removed from the fmb_list when fmb->len becomes 0. */
328 struct tomoyo_free_memory_block_list *fmb;
331 struct list_head *head;
335 len = strlen(name) + 1;
336 if (len > TOMOYO_MAX_PATHNAME_LEN) {
337 printk(KERN_WARNING "ERROR: Name too long "
338 "for tomoyo_save_name().\n");
341 hash = full_name_hash((const unsigned char *) name, len - 1);
342 head = &tomoyo_name_list[hash_long(hash, TOMOYO_HASH_BITS)];
345 list_for_each_entry(ptr, head, list) {
346 if (hash == ptr->entry.hash && !strcmp(name, ptr->entry.name))
349 list_for_each_entry(fmb, &fmb_list, list) {
353 if (!tomoyo_quota_for_savename ||
354 tomoyo_allocated_memory_for_savename + PATH_MAX
355 <= tomoyo_quota_for_savename)
356 cp = kzalloc(PATH_MAX, GFP_KERNEL);
359 fmb = kzalloc(sizeof(*fmb), GFP_KERNEL);
363 printk(KERN_WARNING "ERROR: Out of memory "
364 "for tomoyo_save_name().\n");
365 if (!tomoyo_policy_loaded)
366 panic("MAC Initialization failed.\n");
370 tomoyo_allocated_memory_for_savename += PATH_MAX;
371 list_add(&fmb->list, &fmb_list);
375 ptr = tomoyo_alloc_element(sizeof(*ptr));
378 ptr->entry.name = fmb->ptr;
379 memmove(fmb->ptr, name, len);
380 tomoyo_fill_path_info(&ptr->entry);
383 list_add_tail(&ptr->list, head);
385 list_del(&fmb->list);
390 return ptr ? &ptr->entry : NULL;
394 * tomoyo_realpath_init - Initialize realpath related code.
396 void __init tomoyo_realpath_init(void)
400 BUILD_BUG_ON(TOMOYO_MAX_PATHNAME_LEN > PATH_MAX);
401 for (i = 0; i < TOMOYO_MAX_HASH; i++)
402 INIT_LIST_HEAD(&tomoyo_name_list[i]);
403 INIT_LIST_HEAD(&tomoyo_kernel_domain.acl_info_list);
404 tomoyo_kernel_domain.domainname = tomoyo_save_name(TOMOYO_ROOT_NAME);
405 list_add_tail(&tomoyo_kernel_domain.list, &tomoyo_domain_list);
406 down_read(&tomoyo_domain_list_lock);
407 if (tomoyo_find_domain(TOMOYO_ROOT_NAME) != &tomoyo_kernel_domain)
408 panic("Can't register tomoyo_kernel_domain");
409 up_read(&tomoyo_domain_list_lock);
412 /* Memory allocated for temporary purpose. */
413 static atomic_t tomoyo_dynamic_memory_size;
416 * tomoyo_alloc - Allocate memory for temporary purpose.
418 * @size: Size in bytes.
420 * Returns pointer to allocated memory on success, NULL otherwise.
422 void *tomoyo_alloc(const size_t size)
424 void *p = kzalloc(size, GFP_KERNEL);
426 atomic_add(ksize(p), &tomoyo_dynamic_memory_size);
431 * tomoyo_free - Release memory allocated by tomoyo_alloc().
433 * @p: Pointer returned by tomoyo_alloc(). May be NULL.
437 void tomoyo_free(const void *p)
440 atomic_sub(ksize(p), &tomoyo_dynamic_memory_size);
446 * tomoyo_read_memory_counter - Check for memory usage in bytes.
448 * @head: Pointer to "struct tomoyo_io_buffer".
450 * Returns memory usage.
452 int tomoyo_read_memory_counter(struct tomoyo_io_buffer *head)
454 if (!head->read_eof) {
455 const unsigned int shared
456 = tomoyo_allocated_memory_for_savename;
457 const unsigned int private
458 = tomoyo_allocated_memory_for_elements;
459 const unsigned int dynamic
460 = atomic_read(&tomoyo_dynamic_memory_size);
463 memset(buffer, 0, sizeof(buffer));
464 if (tomoyo_quota_for_savename)
465 snprintf(buffer, sizeof(buffer) - 1,
467 tomoyo_quota_for_savename);
470 tomoyo_io_printf(head, "Shared: %10u%s\n", shared, buffer);
471 if (tomoyo_quota_for_elements)
472 snprintf(buffer, sizeof(buffer) - 1,
474 tomoyo_quota_for_elements);
477 tomoyo_io_printf(head, "Private: %10u%s\n", private, buffer);
478 tomoyo_io_printf(head, "Dynamic: %10u\n", dynamic);
479 tomoyo_io_printf(head, "Total: %10u\n",
480 shared + private + dynamic);
481 head->read_eof = true;
487 * tomoyo_write_memory_quota - Set memory quota.
489 * @head: Pointer to "struct tomoyo_io_buffer".
493 int tomoyo_write_memory_quota(struct tomoyo_io_buffer *head)
495 char *data = head->write_buf;
498 if (sscanf(data, "Shared: %u", &size) == 1)
499 tomoyo_quota_for_savename = size;
500 else if (sscanf(data, "Private: %u", &size) == 1)
501 tomoyo_quota_for_elements = size;