security/tomoyo/realpath.c - kernel/msm - Gitiles

 /*
  * security/tomoyo/realpath.c
  *
  * Get the canonicalized absolute pathnames. The basis for TOMOYO.
  *
  * Copyright (C) 2005-2009  NTT DATA CORPORATION
  *
  * Version: 2.2.0-pre   2009/02/01
  *
  */

 #include <linux/types.h>
 #include <linux/mount.h>
 #include <linux/mnt_namespace.h>
 #include <linux/fs_struct.h>
 #include "common.h"
 #include "realpath.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 {
 		/* Taken from d_namespace_path(). */
 		struct path root;
 		struct path ns_root = { };
 		struct path tmp;

 		read_lock(&current->fs->lock);
 		root = current->fs->root;
 		path_get(&root);
 		read_unlock(&current->fs->lock);
 		spin_lock(&vfsmount_lock);
 		if (root.mnt && root.mnt->mnt_ns)
 			ns_root.mnt = mntget(root.mnt->mnt_ns->root);
 		if (ns_root.mnt)
 			ns_root.dentry = dget(ns_root.mnt->mnt_root);
 		spin_unlock(&vfsmount_lock);
 		spin_lock(&dcache_lock);
 		tmp = ns_root;
 		sp = __d_path(path, &tmp, newname, newname_len);
 		spin_unlock(&dcache_lock);
 		path_put(&root);
 		path_put(&ns_root);
 	}
 	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 tomoyo_alloc(), so the caller must call tomoyo_free()
  * if these functions didn't return NULL.
  */
 char *tomoyo_realpath_from_path(struct path *path)
 {
 	char *buf = tomoyo_alloc(sizeof(struct tomoyo_page_buffer));

 	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;
 	tomoyo_free(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 nameidata nd;

 	if (pathname && path_lookup(pathname, LOOKUP_FOLLOW, &nd) == 0) {
 		char *buf = tomoyo_realpath_from_path(&nd.path);
 		path_put(&nd.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 nameidata nd;

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

 /* Memory allocated for non-string data. */
 static unsigned int tomoyo_allocated_memory_for_elements;
 /* Quota for holding non-string data. */
 static unsigned int tomoyo_quota_for_elements;

 /**
  * tomoyo_alloc_element - Allocate permanent memory for structures.
  *
  * @size: Size in bytes.
  *
  * Returns pointer to allocated memory on success, NULL otherwise.
  *
  * Memory has to be zeroed.
  * The RAM is chunked, so NEVER try to kfree() the returned pointer.
  */
 void *tomoyo_alloc_element(const unsigned int size)
 {
 	static char *buf;
 	static DEFINE_MUTEX(lock);
 	static unsigned int buf_used_len = PATH_MAX;
 	char *ptr = NULL;
 	/*Assumes sizeof(void *) >= sizeof(long) is true. */
 	const unsigned int word_aligned_size
 		= roundup(size, max(sizeof(void *), sizeof(long)));
 	if (word_aligned_size > PATH_MAX)
 		return NULL;
 	/***** EXCLUSIVE SECTION START *****/
 	mutex_lock(&lock);
 	if (buf_used_len + word_aligned_size > PATH_MAX) {
 		if (!tomoyo_quota_for_elements ||
 		    tomoyo_allocated_memory_for_elements
 		    + PATH_MAX <= tomoyo_quota_for_elements)
 			ptr = kzalloc(PATH_MAX, GFP_KERNEL);
 		if (!ptr) {
 			printk(KERN_WARNING "ERROR: Out of memory "
 			       "for tomoyo_alloc_element().\n");
 			if (!tomoyo_policy_loaded)
 				panic("MAC Initialization failed.\n");
 		} else {
 			buf = ptr;
 			tomoyo_allocated_memory_for_elements += PATH_MAX;
 			buf_used_len = word_aligned_size;
 			ptr = buf;
 		}
 	} else if (word_aligned_size) {
 		int i;
 		ptr = buf + buf_used_len;
 		buf_used_len += word_aligned_size;
 		for (i = 0; i < word_aligned_size; i++) {
 			if (!ptr[i])
 				continue;
 			printk(KERN_ERR "WARNING: Reserved memory was tainted! "
 			       "The system might go wrong.\n");
 			ptr[i] = '\0';
 		}
 	}
 	mutex_unlock(&lock);
 	/***** EXCLUSIVE SECTION END *****/
 	return ptr;
 }

 /* Memory allocated for string data in bytes. */
 static unsigned int tomoyo_allocated_memory_for_savename;
 /* Quota for holding string data in bytes. */
 static unsigned int tomoyo_quota_for_savename;

 /*
  * TOMOYO uses this hash only when appending a string into the string
  * table. Frequency of appending strings is very low. So we don't need
  * large (e.g. 64k) hash size. 256 will be sufficient.
  */
 #define TOMOYO_MAX_HASH 256

 /* Structure for string data. */
 struct tomoyo_name_entry {
 	struct list_head list;
 	struct tomoyo_path_info entry;
 };

 /* Structure for available memory region. */
 struct tomoyo_free_memory_block_list {
 	struct list_head list;
 	char *ptr;             /* Pointer to a free area. */
 	int len;               /* Length of the area.     */
 };

 /*
  * The list for "struct tomoyo_name_entry".
  *
  * This list is updated only inside tomoyo_save_name(), thus
  * no global mutex exists.
  */
 static struct list_head tomoyo_name_list[TOMOYO_MAX_HASH];

 /**
  * tomoyo_save_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.
  *
  * The RAM is shared, so NEVER try to modify or kfree() the returned name.
  */
 const struct tomoyo_path_info *tomoyo_save_name(const char *name)
 {
 	static LIST_HEAD(fmb_list);
 	static DEFINE_MUTEX(lock);
 	struct tomoyo_name_entry *ptr;
 	unsigned int hash;
 	/* fmb contains available size in bytes.
 	   fmb is removed from the fmb_list when fmb->len becomes 0. */
 	struct tomoyo_free_memory_block_list *fmb;
 	int len;
 	char *cp;

 	if (!name)
 		return NULL;
 	len = strlen(name) + 1;
 	if (len > TOMOYO_MAX_PATHNAME_LEN) {
 		printk(KERN_WARNING "ERROR: Name too long "
 		       "for tomoyo_save_name().\n");
 		return NULL;
 	}
 	hash = full_name_hash((const unsigned char *) name, len - 1);
 	/***** EXCLUSIVE SECTION START *****/
 	mutex_lock(&lock);
 	list_for_each_entry(ptr, &tomoyo_name_list[hash % TOMOYO_MAX_HASH],
 			     list) {
 		if (hash == ptr->entry.hash && !strcmp(name, ptr->entry.name))
 			goto out;
 	}
 	list_for_each_entry(fmb, &fmb_list, list) {
 		if (len <= fmb->len)
 			goto ready;
 	}
 	if (!tomoyo_quota_for_savename ||
 	    tomoyo_allocated_memory_for_savename + PATH_MAX
 	    <= tomoyo_quota_for_savename)
 		cp = kzalloc(PATH_MAX, GFP_KERNEL);
 	else
 		cp = NULL;
 	fmb = kzalloc(sizeof(*fmb), GFP_KERNEL);
 	if (!cp || !fmb) {
 		kfree(cp);
 		kfree(fmb);
 		printk(KERN_WARNING "ERROR: Out of memory "
 		       "for tomoyo_save_name().\n");
 		if (!tomoyo_policy_loaded)
 			panic("MAC Initialization failed.\n");
 		ptr = NULL;
 		goto out;
 	}
 	tomoyo_allocated_memory_for_savename += PATH_MAX;
 	list_add(&fmb->list, &fmb_list);
 	fmb->ptr = cp;
 	fmb->len = PATH_MAX;
  ready:
 	ptr = tomoyo_alloc_element(sizeof(*ptr));
 	if (!ptr)
 		goto out;
 	ptr->entry.name = fmb->ptr;
 	memmove(fmb->ptr, name, len);
 	tomoyo_fill_path_info(&ptr->entry);
 	fmb->ptr += len;
 	fmb->len -= len;
 	list_add_tail(&ptr->list, &tomoyo_name_list[hash % TOMOYO_MAX_HASH]);
 	if (fmb->len == 0) {
 		list_del(&fmb->list);
 		kfree(fmb);
 	}
  out:
 	mutex_unlock(&lock);
 	/***** EXCLUSIVE SECTION END *****/
 	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_save_name(TOMOYO_ROOT_NAME);
 	list_add_tail(&tomoyo_kernel_domain.list, &tomoyo_domain_list);
 	down_read(&tomoyo_domain_list_lock);
 	if (tomoyo_find_domain(TOMOYO_ROOT_NAME) != &tomoyo_kernel_domain)
 		panic("Can't register tomoyo_kernel_domain");
 	up_read(&tomoyo_domain_list_lock);
 }

 /* Memory allocated for temporary purpose. */
 static atomic_t tomoyo_dynamic_memory_size;

 /**
  * tomoyo_alloc - Allocate memory for temporary purpose.
  *
  * @size: Size in bytes.
  *
  * Returns pointer to allocated memory on success, NULL otherwise.
  */
 void *tomoyo_alloc(const size_t size)
 {
 	void *p = kzalloc(size, GFP_KERNEL);
 	if (p)
 		atomic_add(ksize(p), &tomoyo_dynamic_memory_size);
 	return p;
 }

 /**
  * tomoyo_free - Release memory allocated by tomoyo_alloc().
  *
  * @p: Pointer returned by tomoyo_alloc(). May be NULL.
  *
  * Returns nothing.
  */
 void tomoyo_free(const void *p)
 {
 	if (p) {
 		atomic_sub(ksize(p), &tomoyo_dynamic_memory_size);
 		kfree(p);
 	}
 }

 /**
  * 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 shared
 			= tomoyo_allocated_memory_for_savename;
 		const unsigned int private
 			= tomoyo_allocated_memory_for_elements;
 		const unsigned int dynamic
 			= atomic_read(&tomoyo_dynamic_memory_size);
 		char buffer[64];

 		memset(buffer, 0, sizeof(buffer));
 		if (tomoyo_quota_for_savename)
 			snprintf(buffer, sizeof(buffer) - 1,
 				 "   (Quota: %10u)",
 				 tomoyo_quota_for_savename);
 		else
 			buffer[0] = '\0';
 		tomoyo_io_printf(head, "Shared:  %10u%s\n", shared, buffer);
 		if (tomoyo_quota_for_elements)
 			snprintf(buffer, sizeof(buffer) - 1,
 				 "   (Quota: %10u)",
 				 tomoyo_quota_for_elements);
 		else
 			buffer[0] = '\0';
 		tomoyo_io_printf(head, "Private: %10u%s\n", private, buffer);
 		tomoyo_io_printf(head, "Dynamic: %10u\n", dynamic);
 		tomoyo_io_printf(head, "Total:   %10u\n",
 				 shared + private + dynamic);
 		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, "Shared: %u", &size) == 1)
 		tomoyo_quota_for_savename = size;
 	else if (sscanf(data, "Private: %u", &size) == 1)
 		tomoyo_quota_for_elements = size;
 	return 0;
 }
	/*
	* security/tomoyo/realpath.c
	*
	* Get the canonicalized absolute pathnames. The basis for TOMOYO.
	*
	* Copyright (C) 2005-2009 NTT DATA CORPORATION
	*
	* Version: 2.2.0-pre 2009/02/01
	*
	*/

	#include <linux/types.h>
	#include <linux/mount.h>
	#include <linux/mnt_namespace.h>
	#include <linux/fs_struct.h>
	#include "common.h"
	#include "realpath.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 {
	/* Taken from d_namespace_path(). */
	struct path root;
	struct path ns_root = { };
	struct path tmp;

	read_lock(&current->fs->lock);
	root = current->fs->root;
	path_get(&root);
	read_unlock(&current->fs->lock);
	spin_lock(&vfsmount_lock);
	if (root.mnt && root.mnt->mnt_ns)
	ns_root.mnt = mntget(root.mnt->mnt_ns->root);
	if (ns_root.mnt)
	ns_root.dentry = dget(ns_root.mnt->mnt_root);
	spin_unlock(&vfsmount_lock);
	spin_lock(&dcache_lock);
	tmp = ns_root;
	sp = __d_path(path, &tmp, newname, newname_len);
	spin_unlock(&dcache_lock);
	path_put(&root);
	path_put(&ns_root);
	}
	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 tomoyo_alloc(), so the caller must call tomoyo_free()
	* if these functions didn't return NULL.
	*/
	char tomoyo_realpath_from_path(struct path path)
	{
	char *buf = tomoyo_alloc(sizeof(struct tomoyo_page_buffer));

	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;
	tomoyo_free(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 nameidata nd;

	if (pathname && path_lookup(pathname, LOOKUP_FOLLOW, &nd) == 0) {
	char *buf = tomoyo_realpath_from_path(&nd.path);
	path_put(&nd.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 nameidata nd;

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

	/* Memory allocated for non-string data. */
	static unsigned int tomoyo_allocated_memory_for_elements;
	/* Quota for holding non-string data. */
	static unsigned int tomoyo_quota_for_elements;

	/**
	* tomoyo_alloc_element - Allocate permanent memory for structures.
	*
	* @size: Size in bytes.
	*
	* Returns pointer to allocated memory on success, NULL otherwise.
	*
	* Memory has to be zeroed.
	* The RAM is chunked, so NEVER try to kfree() the returned pointer.
	*/
	void *tomoyo_alloc_element(const unsigned int size)
	{
	static char *buf;
	static DEFINE_MUTEX(lock);
	static unsigned int buf_used_len = PATH_MAX;
	char *ptr = NULL;
	/Assumes sizeof(void ) >= sizeof(long) is true. */
	const unsigned int word_aligned_size
	= roundup(size, max(sizeof(void *), sizeof(long)));
	if (word_aligned_size > PATH_MAX)
	return NULL;
	/*** EXCLUSIVE SECTION START ***/
	mutex_lock(&lock);
	if (buf_used_len + word_aligned_size > PATH_MAX) {
	if (!tomoyo_quota_for_elements \|\|
	tomoyo_allocated_memory_for_elements
	+ PATH_MAX <= tomoyo_quota_for_elements)
	ptr = kzalloc(PATH_MAX, GFP_KERNEL);
	if (!ptr) {
	printk(KERN_WARNING "ERROR: Out of memory "
	"for tomoyo_alloc_element().\n");
	if (!tomoyo_policy_loaded)
	panic("MAC Initialization failed.\n");
	} else {
	buf = ptr;
	tomoyo_allocated_memory_for_elements += PATH_MAX;
	buf_used_len = word_aligned_size;
	ptr = buf;
	}
	} else if (word_aligned_size) {
	int i;
	ptr = buf + buf_used_len;
	buf_used_len += word_aligned_size;
	for (i = 0; i < word_aligned_size; i++) {
	if (!ptr[i])
	continue;
	printk(KERN_ERR "WARNING: Reserved memory was tainted! "
	"The system might go wrong.\n");
	ptr[i] = '\0';
	}
	}
	mutex_unlock(&lock);
	/*** EXCLUSIVE SECTION END ***/
	return ptr;
	}

	/* Memory allocated for string data in bytes. */
	static unsigned int tomoyo_allocated_memory_for_savename;
	/* Quota for holding string data in bytes. */
	static unsigned int tomoyo_quota_for_savename;

	/*
	* TOMOYO uses this hash only when appending a string into the string
	* table. Frequency of appending strings is very low. So we don't need
	* large (e.g. 64k) hash size. 256 will be sufficient.
	*/
	#define TOMOYO_MAX_HASH 256

	/* Structure for string data. */
	struct tomoyo_name_entry {
	struct list_head list;
	struct tomoyo_path_info entry;
	};

	/* Structure for available memory region. */
	struct tomoyo_free_memory_block_list {
	struct list_head list;
	char ptr; / Pointer to a free area. */
	int len; /* Length of the area. */
	};

	/*
	* The list for "struct tomoyo_name_entry".
	*
	* This list is updated only inside tomoyo_save_name(), thus
	* no global mutex exists.
	*/
	static struct list_head tomoyo_name_list[TOMOYO_MAX_HASH];

	/**
	* tomoyo_save_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.
	*
	* The RAM is shared, so NEVER try to modify or kfree() the returned name.
	*/
	const struct tomoyo_path_info tomoyo_save_name(const char name)
	{
	static LIST_HEAD(fmb_list);
	static DEFINE_MUTEX(lock);
	struct tomoyo_name_entry *ptr;
	unsigned int hash;
	/* fmb contains available size in bytes.
	fmb is removed from the fmb_list when fmb->len becomes 0. */
	struct tomoyo_free_memory_block_list *fmb;
	int len;
	char *cp;

	if (!name)
	return NULL;
	len = strlen(name) + 1;
	if (len > TOMOYO_MAX_PATHNAME_LEN) {
	printk(KERN_WARNING "ERROR: Name too long "
	"for tomoyo_save_name().\n");
	return NULL;
	}
	hash = full_name_hash((const unsigned char *) name, len - 1);
	/*** EXCLUSIVE SECTION START ***/
	mutex_lock(&lock);
	list_for_each_entry(ptr, &tomoyo_name_list[hash % TOMOYO_MAX_HASH],
	list) {
	if (hash == ptr->entry.hash && !strcmp(name, ptr->entry.name))
	goto out;
	}
	list_for_each_entry(fmb, &fmb_list, list) {
	if (len <= fmb->len)
	goto ready;
	}
	if (!tomoyo_quota_for_savename \|\|
	tomoyo_allocated_memory_for_savename + PATH_MAX
	<= tomoyo_quota_for_savename)
	cp = kzalloc(PATH_MAX, GFP_KERNEL);
	else
	cp = NULL;
	fmb = kzalloc(sizeof(*fmb), GFP_KERNEL);
	if (!cp \|\| !fmb) {
	kfree(cp);
	kfree(fmb);
	printk(KERN_WARNING "ERROR: Out of memory "
	"for tomoyo_save_name().\n");
	if (!tomoyo_policy_loaded)
	panic("MAC Initialization failed.\n");
	ptr = NULL;
	goto out;
	}
	tomoyo_allocated_memory_for_savename += PATH_MAX;
	list_add(&fmb->list, &fmb_list);
	fmb->ptr = cp;
	fmb->len = PATH_MAX;
	ready:
	ptr = tomoyo_alloc_element(sizeof(*ptr));
	if (!ptr)
	goto out;
	ptr->entry.name = fmb->ptr;
	memmove(fmb->ptr, name, len);
	tomoyo_fill_path_info(&ptr->entry);
	fmb->ptr += len;
	fmb->len -= len;
	list_add_tail(&ptr->list, &tomoyo_name_list[hash % TOMOYO_MAX_HASH]);
	if (fmb->len == 0) {
	list_del(&fmb->list);
	kfree(fmb);
	}
	out:
	mutex_unlock(&lock);
	/*** EXCLUSIVE SECTION END ***/
	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_save_name(TOMOYO_ROOT_NAME);
	list_add_tail(&tomoyo_kernel_domain.list, &tomoyo_domain_list);
	down_read(&tomoyo_domain_list_lock);
	if (tomoyo_find_domain(TOMOYO_ROOT_NAME) != &tomoyo_kernel_domain)
	panic("Can't register tomoyo_kernel_domain");
	up_read(&tomoyo_domain_list_lock);
	}

	/* Memory allocated for temporary purpose. */
	static atomic_t tomoyo_dynamic_memory_size;

	/**
	* tomoyo_alloc - Allocate memory for temporary purpose.
	*
	* @size: Size in bytes.
	*
	* Returns pointer to allocated memory on success, NULL otherwise.
	*/
	void *tomoyo_alloc(const size_t size)
	{
	void *p = kzalloc(size, GFP_KERNEL);
	if (p)
	atomic_add(ksize(p), &tomoyo_dynamic_memory_size);
	return p;
	}

	/**
	* tomoyo_free - Release memory allocated by tomoyo_alloc().
	*
	* @p: Pointer returned by tomoyo_alloc(). May be NULL.
	*
	* Returns nothing.
	*/
	void tomoyo_free(const void *p)
	{
	if (p) {
	atomic_sub(ksize(p), &tomoyo_dynamic_memory_size);
	kfree(p);
	}
	}

	/**
	* 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 shared
	= tomoyo_allocated_memory_for_savename;
	const unsigned int private
	= tomoyo_allocated_memory_for_elements;
	const unsigned int dynamic
	= atomic_read(&tomoyo_dynamic_memory_size);
	char buffer[64];

	memset(buffer, 0, sizeof(buffer));
	if (tomoyo_quota_for_savename)
	snprintf(buffer, sizeof(buffer) - 1,
	" (Quota: %10u)",
	tomoyo_quota_for_savename);
	else
	buffer[0] = '\0';
	tomoyo_io_printf(head, "Shared: %10u%s\n", shared, buffer);
	if (tomoyo_quota_for_elements)
	snprintf(buffer, sizeof(buffer) - 1,
	" (Quota: %10u)",
	tomoyo_quota_for_elements);
	else
	buffer[0] = '\0';
	tomoyo_io_printf(head, "Private: %10u%s\n", private, buffer);
	tomoyo_io_printf(head, "Dynamic: %10u\n", dynamic);
	tomoyo_io_printf(head, "Total: %10u\n",
	shared + private + dynamic);
	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, "Shared: %u", &size) == 1)
	tomoyo_quota_for_savename = size;
	else if (sscanf(data, "Private: %u", &size) == 1)
	tomoyo_quota_for_elements = size;
	return 0;
	}