TOMOYO: Support longer pathname.

Allow pathnames longer than 4000 bytes.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <jmorris@namei.org>

6 files changed, 208 insertions, 318 deletions

diff --git a/security/tomoyo/common.h b/security/tomoyo/common.h
index 6270a530c4d8..f4a8aa244af5 100644
--- a/security/tomoyo/common.h
+++ b/security/tomoyo/common.h
@@ -33,14 +33,7 @@ struct linux_binprm;
 #define TOMOYO_HASH_BITS  8
 #define TOMOYO_MAX_HASH (1u<<TOMOYO_HASH_BITS)
 
-/*
- * This is the max length of a token.
- *
- * A token consists of only ASCII printable characters.
- * Non printable characters in a token is represented in \ooo style
- * octal string. Thus, \ itself is represented as \\.
- */
-#define TOMOYO_MAX_PATHNAME_LEN 4000
+#define TOMOYO_EXEC_TMPSIZE     4096
 
 /* Profile number is an integer between 0 and 255. */
 #define TOMOYO_MAX_PROFILES 256
@@ -168,17 +161,6 @@ enum tomoyo_securityfs_interface_index {
 /********** Structure definitions. **********/
 
 /*
- * tomoyo_page_buffer is a structure which is used for holding a pathname
- * obtained from "struct dentry" and "struct vfsmount" pair.
- * As of now, it is 4096 bytes. If users complain that 4096 bytes is too small
- * (because TOMOYO escapes non ASCII printable characters using \ooo format),
- * we will make the buffer larger.
- */
-struct tomoyo_page_buffer {
-	char buffer[4096];
-};
-
-/*
  * tomoyo_request_info is a structure which is used for holding
  *
  * (1) Domain information of current process.
@@ -231,28 +213,6 @@ struct tomoyo_name_entry {
 	struct tomoyo_path_info entry;
 };
 
-/*
- * tomoyo_path_info_with_data is a structure which is used for holding a
- * pathname obtained from "struct dentry" and "struct vfsmount" pair.
- *
- * "struct tomoyo_path_info_with_data" consists of "struct tomoyo_path_info"
- * and buffer for the pathname, while "struct tomoyo_page_buffer" consists of
- * buffer for the pathname only.
- *
- * "struct tomoyo_path_info_with_data" is intended to allow TOMOYO to release
- * both "struct tomoyo_path_info" and buffer for the pathname by single kfree()
- * so that we don't need to return two pointers to the caller. If the caller
- * puts "struct tomoyo_path_info" on stack memory, we will be able to remove
- * "struct tomoyo_path_info_with_data".
- */
-struct tomoyo_path_info_with_data {
-	/* Keep "head" first, for this pointer is passed to kfree(). */
-	struct tomoyo_path_info head;
-	char barrier1[16]; /* Safeguard for overrun. */
-	char body[TOMOYO_MAX_PATHNAME_LEN];
-	char barrier2[16]; /* Safeguard for overrun. */
-};
-
 struct tomoyo_name_union {
 	const struct tomoyo_path_info *filename;
 	struct tomoyo_path_group *group;
@@ -827,11 +787,7 @@ void tomoyo_load_policy(const char *filename);
 void tomoyo_put_number_union(struct tomoyo_number_union *ptr);
 
 /* Convert binary string to ascii string. */
-int tomoyo_encode(char *buffer, int buflen, const char *str);
-
-/* Returns realpath(3) of the given pathname but ignores chroot'ed root. */
-int tomoyo_realpath_from_path2(struct path *path, char *newname,
-			       int newname_len);
+char *tomoyo_encode(const char *str);
 
 /*
  * Returns realpath(3) of the given pathname but ignores chroot'ed root.
diff --git a/security/tomoyo/domain.c b/security/tomoyo/domain.c
index 08428bc082df..7b8693e29a13 100644
--- a/security/tomoyo/domain.c
+++ b/security/tomoyo/domain.c
@@ -676,47 +676,43 @@ struct tomoyo_domain_info *tomoyo_find_or_assign_new_domain(const char *
 int tomoyo_find_next_domain(struct linux_binprm *bprm)
 {
 	struct tomoyo_request_info r;
-	/*
-	 * This function assumes that the size of buffer returned by
-	 * tomoyo_realpath() = TOMOYO_MAX_PATHNAME_LEN.
-	 */
-	struct tomoyo_page_buffer *tmp = kzalloc(sizeof(*tmp), GFP_NOFS);
+	char *tmp = kzalloc(TOMOYO_EXEC_TMPSIZE, GFP_NOFS);
 	struct tomoyo_domain_info *old_domain = tomoyo_domain();
 	struct tomoyo_domain_info *domain = NULL;
 	const char *old_domain_name = old_domain->domainname->name;
 	const char *original_name = bprm->filename;
-	char *new_domain_name = NULL;
-	char *real_program_name = NULL;
-	char *symlink_program_name = NULL;
 	const u8 mode = tomoyo_check_flags(old_domain, TOMOYO_MAC_FOR_FILE);
 	const bool is_enforce = (mode == TOMOYO_CONFIG_ENFORCING);
 	int retval = -ENOMEM;
-	struct tomoyo_path_info rn; /* real name */
-	struct tomoyo_path_info sn; /* symlink name */
+	bool need_kfree = false;
+	struct tomoyo_path_info rn = { }; /* real name */
+	struct tomoyo_path_info sn = { }; /* symlink name */
 	struct tomoyo_path_info ln; /* last name */
 
+	ln.name = tomoyo_get_last_name(old_domain);
+	tomoyo_fill_path_info(&ln);
 	tomoyo_init_request_info(&r, NULL);
 	if (!tmp)
 		goto out;
 
  retry:
+	if (need_kfree) {
+		kfree(rn.name);
+		need_kfree = false;
+	}
 	/* Get tomoyo_realpath of program. */
 	retval = -ENOENT;
-	/* I hope tomoyo_realpath() won't fail with -ENOMEM. */
-	real_program_name = tomoyo_realpath(original_name);
-	if (!real_program_name)
+	rn.name = tomoyo_realpath(original_name);
+	if (!rn.name)
 		goto out;
+	tomoyo_fill_path_info(&rn);
+	need_kfree = true;
+
 	/* Get tomoyo_realpath of symbolic link. */
-	symlink_program_name = tomoyo_realpath_nofollow(original_name);
-	if (!symlink_program_name)
+	sn.name = tomoyo_realpath_nofollow(original_name);
+	if (!sn.name)
 		goto out;
-
-	rn.name = real_program_name;
-	tomoyo_fill_path_info(&rn);
-	sn.name = symlink_program_name;
 	tomoyo_fill_path_info(&sn);
-	ln.name = tomoyo_get_last_name(old_domain);
-	tomoyo_fill_path_info(&ln);
 
 	/* Check 'alias' directive. */
 	if (tomoyo_pathcmp(&rn, &sn)) {
@@ -727,10 +723,10 @@ int tomoyo_find_next_domain(struct linux_binprm *bprm)
 			    tomoyo_pathcmp(&rn, ptr->original_name) ||
 			    tomoyo_pathcmp(&sn, ptr->aliased_name))
 				continue;
-			memset(real_program_name, 0, TOMOYO_MAX_PATHNAME_LEN);
-			strncpy(real_program_name, ptr->aliased_name->name,
-				TOMOYO_MAX_PATHNAME_LEN - 1);
-			tomoyo_fill_path_info(&rn);
+			kfree(rn.name);
+			need_kfree = false;
+			/* This is OK because it is read only. */
+			rn = *ptr->aliased_name;
 			break;
 		}
 	}
@@ -742,11 +738,10 @@ int tomoyo_find_next_domain(struct linux_binprm *bprm)
 	if (retval < 0)
 		goto out;
 
-	new_domain_name = tmp->buffer;
 	if (tomoyo_is_domain_initializer(old_domain->domainname, &rn, &ln)) {
 		/* Transit to the child of tomoyo_kernel_domain domain. */
-		snprintf(new_domain_name, TOMOYO_MAX_PATHNAME_LEN + 1,
-			 TOMOYO_ROOT_NAME " " "%s", real_program_name);
+		snprintf(tmp, TOMOYO_EXEC_TMPSIZE - 1,
+			 TOMOYO_ROOT_NAME " " "%s", rn.name);
 	} else if (old_domain == &tomoyo_kernel_domain &&
 		   !tomoyo_policy_loaded) {
 		/*
@@ -760,29 +755,27 @@ int tomoyo_find_next_domain(struct linux_binprm *bprm)
 		domain = old_domain;
 	} else {
 		/* Normal domain transition. */
-		snprintf(new_domain_name, TOMOYO_MAX_PATHNAME_LEN + 1,
-			 "%s %s", old_domain_name, real_program_name);
+		snprintf(tmp, TOMOYO_EXEC_TMPSIZE - 1,
+			 "%s %s", old_domain_name, rn.name);
 	}
-	if (domain || strlen(new_domain_name) >= TOMOYO_MAX_PATHNAME_LEN)
+	if (domain || strlen(tmp) >= TOMOYO_EXEC_TMPSIZE - 10)
 		goto done;
-	domain = tomoyo_find_domain(new_domain_name);
+	domain = tomoyo_find_domain(tmp);
 	if (domain)
 		goto done;
 	if (is_enforce) {
 		int error = tomoyo_supervisor(&r, "# wants to create domain\n"
-					      "%s\n", new_domain_name);
+					      "%s\n", tmp);
 		if (error == TOMOYO_RETRY_REQUEST)
 			goto retry;
 		if (error < 0)
 			goto done;
 	}
-	domain = tomoyo_find_or_assign_new_domain(new_domain_name,
-						  old_domain->profile);
+	domain = tomoyo_find_or_assign_new_domain(tmp, old_domain->profile);
  done:
 	if (domain)
 		goto out;
-	printk(KERN_WARNING "TOMOYO-ERROR: Domain '%s' not defined.\n",
-	       new_domain_name);
+	printk(KERN_WARNING "TOMOYO-ERROR: Domain '%s' not defined.\n", tmp);
 	if (is_enforce)
 		retval = -EPERM;
 	else
@@ -793,8 +786,9 @@ int tomoyo_find_next_domain(struct linux_binprm *bprm)
 	/* Update reference count on "struct tomoyo_domain_info". */
 	atomic_inc(&domain->users);
 	bprm->cred->security = domain;
-	kfree(real_program_name);
-	kfree(symlink_program_name);
+	if (need_kfree)
+		kfree(rn.name);
+	kfree(sn.name);
 	kfree(tmp);
 	return retval;
 }
diff --git a/security/tomoyo/file.c b/security/tomoyo/file.c
index c13806937dc6..cef685415df1 100644
--- a/security/tomoyo/file.c
+++ b/security/tomoyo/file.c
@@ -148,6 +148,17 @@ const char *tomoyo_path_number2keyword(const u8 operation)
 		? tomoyo_path_number_keyword[operation] : NULL;
 }
 
+static void tomoyo_add_slash(struct tomoyo_path_info *buf)
+{
+	if (buf->is_dir)
+		return;
+	/*
+	 * This is OK because tomoyo_encode() reserves space for appending "/".
+	 */
+	strcat((char *) buf->name, "/");
+	tomoyo_fill_path_info(buf);
+}
+
 /**
  * tomoyo_strendswith - Check whether the token ends with the given token.
  *
@@ -167,30 +178,21 @@ static bool tomoyo_strendswith(const char *name, const char *tail)
 }
 
 /**
- * tomoyo_get_path - Get realpath.
+ * tomoyo_get_realpath - Get realpath.
  *
+ * @buf:  Pointer to "struct tomoyo_path_info".
  * @path: Pointer to "struct path".
  *
- * Returns pointer to "struct tomoyo_path_info" on success, NULL otherwise.
+ * Returns true on success, false otherwise.
  */
-static struct tomoyo_path_info *tomoyo_get_path(struct path *path)
+static bool tomoyo_get_realpath(struct tomoyo_path_info *buf, struct path *path)
 {
-	int error;
-	struct tomoyo_path_info_with_data *buf = kzalloc(sizeof(*buf),
-							 GFP_NOFS);
-
-	if (!buf)
-		return NULL;
-	/* Reserve one byte for appending "/". */
-	error = tomoyo_realpath_from_path2(path, buf->body,
-					   sizeof(buf->body) - 2);
-	if (!error) {
-		buf->head.name = buf->body;
-		tomoyo_fill_path_info(&buf->head);
-		return &buf->head;
+	buf->name = tomoyo_realpath_from_path(path);
+	if (buf->name) {
+		tomoyo_fill_path_info(buf);
+		return true;
 	}
-	kfree(buf);
-	return NULL;
+        return false;
 }
 
 static int tomoyo_update_path2_acl(const u8 type, const char *filename1,
@@ -1259,26 +1261,20 @@ int tomoyo_path_number_perm(const u8 type, struct path *path,
 {
 	struct tomoyo_request_info r;
 	int error = -ENOMEM;
-	struct tomoyo_path_info *buf;
+	struct tomoyo_path_info buf;
 	int idx;
 
 	if (tomoyo_init_request_info(&r, NULL) == TOMOYO_CONFIG_DISABLED ||
 	    !path->mnt || !path->dentry)
 		return 0;
 	idx = tomoyo_read_lock();
-	buf = tomoyo_get_path(path);
-	if (!buf)
+	if (!tomoyo_get_realpath(&buf, path))
 		goto out;
-	if (type == TOMOYO_TYPE_MKDIR && !buf->is_dir) {
-		/*
-		 * tomoyo_get_path() reserves space for appending "/."
-		 */
-		strcat((char *) buf->name, "/");
-		tomoyo_fill_path_info(buf);
-	}
-	error = tomoyo_path_number_perm2(&r, type, buf, number);
+	if (type == TOMOYO_TYPE_MKDIR)
+		tomoyo_add_slash(&buf);
+	error = tomoyo_path_number_perm2(&r, type, &buf, number);
  out:
-	kfree(buf);
+	kfree(buf.name);
 	tomoyo_read_unlock(idx);
 	if (r.mode != TOMOYO_CONFIG_ENFORCING)
 		error = 0;
@@ -1319,7 +1315,7 @@ int tomoyo_check_open_permission(struct tomoyo_domain_info *domain,
 {
 	const u8 acc_mode = ACC_MODE(flag);
 	int error = -ENOMEM;
-	struct tomoyo_path_info *buf;
+	struct tomoyo_path_info buf;
 	struct tomoyo_request_info r;
 	int idx;
 
@@ -1335,8 +1331,7 @@ int tomoyo_check_open_permission(struct tomoyo_domain_info *domain,
 		 */
 		return 0;
 	idx = tomoyo_read_lock();
-	buf = tomoyo_get_path(path);
-	if (!buf)
+	if (!tomoyo_get_realpath(&buf, path))
 		goto out;
 	error = 0;
 	/*
@@ -1346,15 +1341,15 @@ int tomoyo_check_open_permission(struct tomoyo_domain_info *domain,
 	 */
 	if ((acc_mode & MAY_WRITE) &&
 	    ((flag & O_TRUNC) || !(flag & O_APPEND)) &&
-	    (tomoyo_is_no_rewrite_file(buf))) {
-		error = tomoyo_path_permission(&r, TOMOYO_TYPE_REWRITE, buf);
+	    (tomoyo_is_no_rewrite_file(&buf))) {
+		error = tomoyo_path_permission(&r, TOMOYO_TYPE_REWRITE, &buf);
 	}
 	if (!error)
-		error = tomoyo_file_perm(&r, buf, acc_mode);
+		error = tomoyo_file_perm(&r, &buf, acc_mode);
 	if (!error && (flag & O_TRUNC))
-		error = tomoyo_path_permission(&r, TOMOYO_TYPE_TRUNCATE, buf);
+		error = tomoyo_path_permission(&r, TOMOYO_TYPE_TRUNCATE, &buf);
  out:
-	kfree(buf);
+	kfree(buf.name);
 	tomoyo_read_unlock(idx);
 	if (r.mode != TOMOYO_CONFIG_ENFORCING)
 		error = 0;
@@ -1372,7 +1367,7 @@ int tomoyo_check_open_permission(struct tomoyo_domain_info *domain,
 int tomoyo_path_perm(const u8 operation, struct path *path)
 {
 	int error = -ENOMEM;
-	struct tomoyo_path_info *buf;
+	struct tomoyo_path_info buf;
 	struct tomoyo_request_info r;
 	int idx;
 
@@ -1380,29 +1375,23 @@ int tomoyo_path_perm(const u8 operation, struct path *path)
 	    !path->mnt)
 		return 0;
 	idx = tomoyo_read_lock();
-	buf = tomoyo_get_path(path);
-	if (!buf)
+	if (!tomoyo_get_realpath(&buf, path))
 		goto out;
 	switch (operation) {
 	case TOMOYO_TYPE_REWRITE:
-		if (!tomoyo_is_no_rewrite_file(buf)) {
+		if (!tomoyo_is_no_rewrite_file(&buf)) {
 			error = 0;
 			goto out;
 		}
 		break;
 	case TOMOYO_TYPE_RMDIR:
 	case TOMOYO_TYPE_CHROOT:
-		if (!buf->is_dir) {
-			/*
-			 * tomoyo_get_path() reserves space for appending "/."
-			 */
-			strcat((char *) buf->name, "/");
-			tomoyo_fill_path_info(buf);
-		}
+		tomoyo_add_slash(&buf);
+		break;
 	}
-	error = tomoyo_path_permission(&r, operation, buf);
+	error = tomoyo_path_permission(&r, operation, &buf);
  out:
-	kfree(buf);
+	kfree(buf.name);
 	tomoyo_read_unlock(idx);
 	if (r.mode != TOMOYO_CONFIG_ENFORCING)
 		error = 0;
@@ -1465,7 +1454,7 @@ int tomoyo_path_number3_perm(const u8 operation, struct path *path,
 {
 	struct tomoyo_request_info r;
 	int error = -ENOMEM;
-	struct tomoyo_path_info *buf;
+	struct tomoyo_path_info buf;
 	int idx;
 
 	if (tomoyo_init_request_info(&r, NULL) == TOMOYO_CONFIG_DISABLED ||
@@ -1473,11 +1462,10 @@ int tomoyo_path_number3_perm(const u8 operation, struct path *path,
 		return 0;
 	idx = tomoyo_read_lock();
 	error = -ENOMEM;
-	buf = tomoyo_get_path(path);
-	if (buf) {
-		error = tomoyo_path_number3_perm2(&r, operation, buf, mode,
+	if (tomoyo_get_realpath(&buf, path)) {
+		error = tomoyo_path_number3_perm2(&r, operation, &buf, mode,
 						  new_decode_dev(dev));
-		kfree(buf);
+		kfree(buf.name);
 	}
 	tomoyo_read_unlock(idx);
 	if (r.mode != TOMOYO_CONFIG_ENFORCING)
@@ -1499,48 +1487,40 @@ int tomoyo_path2_perm(const u8 operation, struct path *path1,
 {
 	int error = -ENOMEM;
 	const char *msg;
-	struct tomoyo_path_info *buf1;
-	struct tomoyo_path_info *buf2;
+	struct tomoyo_path_info buf1;
+	struct tomoyo_path_info buf2;
 	struct tomoyo_request_info r;
 	int idx;
 
 	if (tomoyo_init_request_info(&r, NULL) == TOMOYO_CONFIG_DISABLED ||
 	    !path1->mnt || !path2->mnt)
 		return 0;
+	buf1.name = NULL;
+	buf2.name = NULL;
 	idx = tomoyo_read_lock();
-	buf1 = tomoyo_get_path(path1);
-	buf2 = tomoyo_get_path(path2);
-	if (!buf1 || !buf2)
+	if (!tomoyo_get_realpath(&buf1, path1) ||
+	    !tomoyo_get_realpath(&buf2, path2))
 		goto out;
 	{
 		struct dentry *dentry = path1->dentry;
 		if (dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)) {
-			/*
-			 * tomoyo_get_path() reserves space for appending "/."
-			 */
-			if (!buf1->is_dir) {
-				strcat((char *) buf1->name, "/");
-				tomoyo_fill_path_info(buf1);
-			}
-			if (!buf2->is_dir) {
-				strcat((char *) buf2->name, "/");
-				tomoyo_fill_path_info(buf2);
-			}
+			tomoyo_add_slash(&buf1);
+			tomoyo_add_slash(&buf2);
 		}
 	}
 	do {
-		error = tomoyo_path2_acl(&r, operation, buf1, buf2);
+		error = tomoyo_path2_acl(&r, operation, &buf1, &buf2);
 		if (!error)
 			break;
 		msg = tomoyo_path22keyword(operation);
-		tomoyo_warn_log(&r, "%s %s %s", msg, buf1->name, buf2->name);
+		tomoyo_warn_log(&r, "%s %s %s", msg, buf1.name, buf2.name);
 		error = tomoyo_supervisor(&r, "allow_%s %s %s\n", msg,
-					  tomoyo_file_pattern(buf1),
-					  tomoyo_file_pattern(buf2));
+					  tomoyo_file_pattern(&buf1),
+					  tomoyo_file_pattern(&buf2));
         } while (error == TOMOYO_RETRY_REQUEST);
  out:
-	kfree(buf1);
-	kfree(buf2);
+	kfree(buf1.name);
+	kfree(buf2.name);
 	tomoyo_read_unlock(idx);
 	if (r.mode != TOMOYO_CONFIG_ENFORCING)
 		error = 0;
diff --git a/security/tomoyo/memory.c b/security/tomoyo/memory.c
index 8fb73ff5cb63..4809febc1acb 100644
--- a/security/tomoyo/memory.c
+++ b/security/tomoyo/memory.c
@@ -153,7 +153,6 @@ void __init tomoyo_mm_init(void)
 {
 	int idx;
 
-	BUILD_BUG_ON(TOMOYO_MAX_PATHNAME_LEN > PATH_MAX);
 	for (idx = 0; idx < TOMOYO_MAX_HASH; idx++)
 		INIT_LIST_HEAD(&tomoyo_name_list[idx]);
 	INIT_LIST_HEAD(&tomoyo_kernel_domain.acl_info_list);
diff --git a/security/tomoyo/mount.c b/security/tomoyo/mount.c
index aeac619f787d..7c1c7fdd3681 100644
--- a/security/tomoyo/mount.c
+++ b/security/tomoyo/mount.c
@@ -25,57 +25,6 @@
 #define TOMOYO_MOUNT_MAKE_SHARED_KEYWORD                 "--make-shared"
 
 /**
- * tomoyo_encode2: Encode binary string to ascii string.
- *
- * @str: String in binary format.
- *
- * Returns pointer to @str in ascii format on success, NULL otherwise.
- *
- * This function uses kzalloc(), so caller must kfree() if this function
- * didn't return NULL.
- */
-static char *tomoyo_encode2(const char *str)
-{
-	int len = 0;
-	const char *p = str;
-	char *cp;
-	char *cp0;
-	if (!p)
-		return NULL;
-	while (*p) {
-		const unsigned char c = *p++;
-		if (c == '\\')
-			len += 2;
-		else if (c > ' ' && c < 127)
-			len++;
-		else
-			len += 4;
-	}
-	len++;
-	/* Reserve space for appending "/". */
-	cp = kzalloc(len + 10, GFP_NOFS);
-	if (!cp)
-		return NULL;
-	cp0 = cp;
-	p = str;
-	while (*p) {
-		const unsigned char c = *p++;
-		if (c == '\\') {
-			*cp++ = '\\';
-			*cp++ = '\\';
-		} else if (c > ' ' && c < 127) {
-			*cp++ = c;
-		} else {
-			*cp++ = '\\';
-			*cp++ = (c >> 6) + '0';
-			*cp++ = ((c >> 3) & 7) + '0';
-			*cp++ = (c & 7) + '0';
-		}
-	}
-	return cp0;
-}
-
-/**
  * tomoyo_mount_acl2 - Check permission for mount() operation.
  *
  * @r:        Pointer to "struct tomoyo_request_info".
@@ -104,7 +53,7 @@ static int tomoyo_mount_acl2(struct tomoyo_request_info *r, char *dev_name,
 	int error = -ENOMEM;
 
 	/* Get fstype. */
-	requested_type = tomoyo_encode2(type);
+	requested_type = tomoyo_encode(type);
 	if (!requested_type)
 		goto out;
 	rtype.name = requested_type;
@@ -155,7 +104,7 @@ static int tomoyo_mount_acl2(struct tomoyo_request_info *r, char *dev_name,
 		/* Map dev_name to "<NULL>" if no dev_name given. */
 		if (!dev_name)
 			dev_name = "<NULL>";
-		requested_dev_name = tomoyo_encode2(dev_name);
+		requested_dev_name = tomoyo_encode(dev_name);
 		if (!requested_dev_name) {
 			error = -ENOMEM;
 			goto out;
diff --git a/security/tomoyo/realpath.c b/security/tomoyo/realpath.c
index 1fd685a94ad1..153fa23a05cc 100644
--- a/security/tomoyo/realpath.c
+++ b/security/tomoyo/realpath.c
@@ -12,141 +12,153 @@
 #include <linux/fs_struct.h>
 #include <linux/magic.h>
 #include <linux/slab.h>
+#include <net/sock.h>
 #include "common.h"
 
 /**
  * tomoyo_encode: Convert binary string to ascii string.
  *
- * @buffer:  Buffer for ASCII string.
- * @buflen:  Size of @buffer.
- * @str:     Binary string.
+ * @str: String in binary format.
  *
- * Returns 0 on success, -ENOMEM otherwise.
+ * Returns pointer to @str in ascii format on success, NULL otherwise.
+ *
+ * This function uses kzalloc(), so caller must kfree() if this function
+ * didn't return NULL.
  */
-int tomoyo_encode(char *buffer, int buflen, const char *str)
+char *tomoyo_encode(const char *str)
 {
-	while (1) {
-		const unsigned char c = *(unsigned char *) str++;
+	int len = 0;
+	const char *p = str;
+	char *cp;
+	char *cp0;
 
-		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;
+	if (!p)
+		return NULL;
+	while (*p) {
+		const unsigned char c = *p++;
+		if (c == '\\')
+			len += 2;
+		else if (c > ' ' && c < 127)
+			len++;
+		else
+			len += 4;
+	}
+	len++;
+	/* Reserve space for appending "/". */
+	cp = kzalloc(len + 10, GFP_NOFS);
+	if (!cp)
+		return NULL;
+	cp0 = cp;
+	p = str;
+	while (*p) {
+		const unsigned char c = *p++;
+
+		if (c == '\\') {
+			*cp++ = '\\';
+			*cp++ = '\\';
+		} else if (c > ' ' && c < 127) {
+			*cp++ = c;
+		} else {
+			*cp++ = '\\';
+			*cp++ = (c >> 6) + '0';
+			*cp++ = ((c >> 3) & 7) + '0';
+			*cp++ = (c & 7) + '0';
 		}
-		buflen -= 4;
-		if (buflen <= 0)
-			break;
-		*buffer++ = '\\';
-		*buffer++ = (c >> 6) + '0';
-		*buffer++ = ((c >> 3) & 7) + '0';
-		*buffer++ = (c & 7) + '0';
 	}
-	return -ENOMEM;
+	return cp0;
 }
 
 /**
- * tomoyo_realpath_from_path2 - Returns realpath(3) of the given dentry but ignores chroot'ed root.
+ * tomoyo_realpath_from_path - Returns realpath(3) of the given pathname but ignores chroot'ed root.
  *
- * @path:        Pointer to "struct path".
- * @newname:     Pointer to buffer to return value in.
- * @newname_len: Size of @newname.
+ * @path: Pointer to "struct path".
  *
- * Returns 0 on success, negative value otherwise.
+ * Returns the realpath of the given @path on success, NULL 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.
+ *
+ * These functions use kzalloc(), so the caller must call kfree()
+ * if these functions didn't return NULL.
  */
-int tomoyo_realpath_from_path2(struct path *path, char *newname,
-			       int newname_len)
+char *tomoyo_realpath_from_path(struct path *path)
 {
-	int error = -ENOMEM;
+	char *buf = NULL;
+	char *name = NULL;
+	unsigned int buf_len = PAGE_SIZE / 2;
 	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) {
+	bool is_dir;
+	if (!dentry)
+		return NULL;
+	is_dir = dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode);
+	while (1) {
+		struct path ns_root = { .mnt = NULL, .dentry = NULL };
+		char *pos;
+		buf_len <<= 1;
+		kfree(buf);
+		buf = kmalloc(buf_len, GFP_NOFS);
+		if (!buf)
+			break;
+		/* Get better name for socket. */
+		if (dentry->d_sb && dentry->d_sb->s_magic == SOCKFS_MAGIC) {
+			struct inode *inode = dentry->d_inode;
+			struct socket *sock = inode ? SOCKET_I(inode) : NULL;
+			struct sock *sk = sock ? sock->sk : NULL;
+			if (sk) {
+				snprintf(buf, buf_len - 1, "socket:[family=%u:"
+					 "type=%u:protocol=%u]", sk->sk_family,
+					 sk->sk_type, sk->sk_protocol);
+			} else {
+				snprintf(buf, buf_len - 1, "socket:[unknown]");
+			}
+			name = tomoyo_encode(buf);
+			break;
+		}
 		/* 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};
-
+		if (dentry->d_op && dentry->d_op->d_dname) {
+			pos = dentry->d_op->d_dname(dentry, buf, buf_len - 1);
+			if (IS_ERR(pos))
+				continue;
+			name = tomoyo_encode(pos);
+			break;
+		}
+		/* If we don't have a vfsmount, we can't calculate. */
+		if (!path->mnt)
+			break;
 		spin_lock(&dcache_lock);
 		/* go to whatever namespace root we are under */
-		sp = __d_path(path, &ns_root, newname, newname_len);
+		pos = __d_path(path, &ns_root, buf, buf_len);
 		spin_unlock(&dcache_lock);
 		/* Prepend "/proc" prefix if using internal proc vfs mount. */
-		if (!IS_ERR(sp) && (path->mnt->mnt_flags & MNT_INTERNAL) &&
+		if (!IS_ERR(pos) && (path->mnt->mnt_flags & MNT_INTERNAL) &&
 		    (path->mnt->mnt_sb->s_magic == PROC_SUPER_MAGIC)) {
-			sp -= 5;
-			if (sp >= newname)
-				memcpy(sp, "/proc", 5);
+			pos -= 5;
+			if (pos >= buf)
+				memcpy(pos, "/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;
-			}
+				pos = ERR_PTR(-ENOMEM);
 		}
+		if (IS_ERR(pos))
+			continue;
+		name = tomoyo_encode(pos);
+		break;
 	}
-	if (error)
-		tomoyo_warn_oom(__func__);
-	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(TOMOYO_MAX_PATHNAME_LEN > PATH_MAX);
-	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;
+	if (!name)
+		tomoyo_warn_oom(__func__);
+	else if (is_dir && *name) {
+		/* Append trailing '/' if dentry is a directory. */
+		char *pos = name + strlen(name) - 1;
+		if (*pos != '/')
+			/*
+			 * This is OK because tomoyo_encode() reserves space
+			 * for appending "/".
+			 */
+			*++pos = '/';
+	}
+	return name;
 }
 
 /**