JP4213430B2 - File system integrity guarantee method, computer system capable of realizing integrity guaranteeable file system, file system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a computer system, and more particularly to a method for ensuring the integrity of data stored as a file system.
[0002]
[Prior art]
The computer system stores data that the user wants to store for a long time in a disk storage device, and when the user requests the data later, the data can be read from the disk storage device again, enabling long-term use of the data And
[0003]
The computer and the disk storage device are connected via a bus, a network, or the like, and the computer and the disk storage device may be managed individually. However, a user who can physically access the disk storage device can illegally change data stored by other users.
[0004]
However, even an administrator of a disk storage device is not preferable that an unauthorized change is possible in order to save a highly important file.
[0005]
Therefore, from the viewpoint of preventing unauthorized change processing, a fill system that uses a one-way function to guarantee file integrity is used.
[0006]
K. Fu proposed a method to guarantee file integrity by applying a one-way function to data blocks (Kevin Fu; Group sharing and random access in cryptographic storage file systems.: Master's thesis, Massachusetts Institute of Technology, May 1999). Here, FIG. 2 is used to explain how this method guarantees data integrity by modifying the conventional file system.
[0007]
A conventional file system physically divides a disk storage device into fixed lengths, calls them blocks, and manages them by assigning numbers in order. The file system has a logical structure as indicated by 101 in FIG. This file system manages each file name and a key value (hereinafter referred to as an “i-node number”) for identifying the location in the disk storage device, so that it is suitable for the request from the user. Returns the data.
[0008]
The file logical structure 106 is called an “i-node” and includes information about the file such as its size and creation time. The i-nodes are stored in a block at a predetermined position in the file system called “i-node table” 104 in the order of i-node numbers. The i-node includes the block number of the data block 105 in which the actual file content is stored. When the i-node number is specified, the file content can be read from the disk storage device.
[0009]
K. mentioned above. In the method of Fu et al., As shown in the file logical structure 201 in FIG. 3, the inode stores a block number of a data block and a hash value obtained by applying a one-way function to each data block as a set. . Then, after reading the data block from the disk storage device, the hash value is obtained by applying a one-way function to the data block, and compared with the hash value stored in each i-node. Guarantee completeness individually. Further, in order to guarantee the integrity of the entire i-node, a hash value obtained by applying the keyed one-way function to the i-node is stored in the i-node.
[0010]
[Problems to be solved by the invention]
However, as described above, K.A. The method of Fu et al. Guarantees only the integrity of the file, and cannot guarantee the integrity of the entire file system. That is, as shown in FIG. 2, the file system has a data block bitmap 102 for managing use / non-use of data blocks and an i-node bitmap 103 for managing use / non-use of inode numbers. Other than the data blocks constituting the file data, etc., the completeness of these blocks cannot be guaranteed.
[0011]
The present invention has been made in view of the above-described circumstances, and aims to guarantee not only the integrity of a file but also the integrity of the entire file system.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 is a file system integrity guarantee method for managing a disk storage device by dividing it into logical blocks, and comprising a plurality of lowest layer blocks. An i-node composed of a plurality of intermediate layer blocks including a plurality of files in a lower layer, a hash value and a block number of each lowest layer block constituting the file in an i-node which is a logical structure of each file Each inode is included in a table file, and an inode having a high update frequency and an inode having a low update frequency are included in another intermediate layer block, and each of the inodes is added to a root inode which is a logical structure of the inode table file Including a portion including a hash value and block number of an intermediate layer block and a hash value obtained by applying a one-way function with a key to the portion; Is integrity assurance method of file system that is characterized in that the inclusion of the route i node to the uppermost block one.
[0014]
The invention according to claim 2 is a computer system capable of realizing a file system for managing a disk storage device by dividing it into logical blocks, wherein a plurality of files are stored in a lowermost layer composed of a plurality of lowermost blocks. The i-node which is the logical structure of each file includes the hash value and block number of each lower-layer block constituting the file, and each i-node table file composed of a plurality of middle-layer blocks includes the i-node table file. A node is included, and an inode having a high update frequency and an inode having a low update frequency are included in another intermediate layer block, and a hash value of each intermediate layer block is stored in a root inode which is a logical structure of the i node table file And a portion including the block number and a hash value obtained by applying a keyed one-way function to the portion. A computer system capable of realizing a file system that is characterized in that the inclusion of the route i node in the layer block.
[0015]
The invention according to claim 4 is an integrity assurance program for a file system that manages a disk storage device by dividing it into logical blocks, and includes a plurality of files in the lowest layer composed of a plurality of lowest layer blocks. In addition, the inode that is the logical structure of each file includes the hash value and block number of each lowest layer block that constitutes the file, and each inode table file that includes a plurality of intermediate layer blocks includes , And an inode having a high update frequency and an inode having a low update frequency are included in another intermediate layer block, and a hash value of each intermediate layer block is included in a root inode which is a logical structure of the i node table file. A block containing the block number and a hash value obtained by applying a one-way function with a key to the block are included. It is a file system integrity assurance program in which said executing the inclusion of the route i node to the computer.
[0016]
Here, the “program” in the present invention means an ordered sequence of instructions suitable for processing by a computer, and is installed in a computer HDD, CD-RW, etc., or a CD-ROM. , DVD, FD (floppy (registered trademark) disk), semiconductor memory, recorded on various recording media such as computer HDD, and distributed via an external network such as the Internet.
[0017]
According to a fourth aspect of the present invention, there is provided a computer readable file system integrity assurance recording medium , wherein the file system integrity assurance program according to the third aspect is recorded.
[0018]
Here, the “recording medium” in the present invention is only required to be able to be used for reading a program for realizing the above processing in the computer system, and how information is recorded using physical characteristics of the medium. It does not depend on the physical recording method such as For example, FD, CD-ROM (R, RW), DVD-ROM (RAM, R, RW), semiconductor memory, MO, MD, magnetic tape, and the like are applicable.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. The file system integrity guarantee method of the present invention can be realized by a computer (system). For this purpose, the integrity guarantee program (p) is stored in the computer, and can be realized. A recording medium such as a CD-ROM in which the program (p) is recorded is used.
[0020]
(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIG.
[0021]
FIG. 1 is a diagram showing a logical structure 10 of the file system according to the first embodiment. This file system has a tree structure with one root inode 15 as a root. The root i-node 15 is usually a logical structure 17 that corresponds to the i-node table 104 of the above-described file system and represents an i-node table file 13 that stores all i-nodes of the file system in the order of i-node numbers. As shown in FIG. 1, the root i-node 15 stores the block number of the data block of the i-node table file 13 and its hash value as a set. Thereby, the integrity of the i-node table file 13 is guaranteed. Further, in order to guarantee the integrity of the root i-node 15, a hash value obtained by applying a one-way function with a key is stored in the root i-node 15 itself.
[0022]
The logical structure 16 of other normal i-nodes excluding the root i-node 13 is the same as the root i-node 15 except that the hash value of the i-node itself is not stored. Since the i-node integrity guarantees the integrity of the i-node table file 13 by the root i-node 15, it is not necessary to store a hash value in the i-node.
[0023]
The block bitmap file 11 corresponds to the block bitmap 102 described above. By predetermining the i-node number of the block bitmap file 11, the block bitmap file 11 can be reached from the i-node table file 13, and at the same time, the integrity of the block bitmap file 11 is obtained by using a hash value. Can also be guaranteed.
[0024]
Further, the i-node bitmap file 12 corresponds to the above-described i-node bitmap 103. By predetermining the i-node number of the i-node bitmap file 12, the i-node bitmap file 12 can be reached from the i-node table file 13 and simultaneously using the hash value, the i-node bitmap file 12 Completeness can also be guaranteed.
[0025]
In addition, an i-node of a normal file is also included in the i-node table file 13, and as with the block bitmap file 11 and the i-node bitmap file 12, the integrity of the data block 14 of the file can be guaranteed. .
[0026]
As described above, according to the present embodiment, a data block bitmap used for managing use / non-use of data blocks in the conventional file system, and use / non-use of i-node numbers are managed. Each i-node bitmap is also filed and managed, and a specific i-node number is assigned in advance. In order to guarantee the integrity of the root i-node, a hash value obtained by applying the keyed one-way function to the root i-node is stored in the root i-node. As a result, all blocks in the file system except for the block where the root inode is stored are managed as files, and a set of block numbers and their hash values are used from the root inode to create a tree structure each time a file is read. By tracing the blocks in order, the integrity of all blocks except the block where the root inode is stored can be guaranteed. Therefore, it is possible to guarantee the integrity of all blocks constituting the file system.
[0027]
(Second Embodiment)
Hereinafter, a second embodiment of the present invention will be described with reference to FIG.
[0028]
The second embodiment is based on the first embodiment, and the i-node table file 3 in the first embodiment is classified according to the update frequency of the i-node. Is stored in a separate block, thereby reducing the number of processings of the one-way function and improving the performance. That is, the i-node table file 3 is stored in another block by dividing all the i-nodes of the file system not by the order of i-node numbers but by their update frequency. When an arbitrary inode is updated, it is necessary to obtain a hash function of the entire block in which the inode is stored. Therefore, if inodes with a high update frequency are distributed over many blocks, the hash function However, the number of executions of the hash function is reduced by dividing the inode into several groups according to the update frequency and storing them in individual blocks.
[0029]
【The invention's effect】
As described above, according to the present invention, blocks other than the data blocks constituting the file system (for example, data block bitmaps, i-node bitmaps, etc.) are also managed as files, and data is stored in the i-node structure. By storing the block number of the block and the hash value of the block as a pair, the integrity of the entire file system can be guaranteed.
[Brief description of the drawings]
FIG. 1 is a diagram showing a file system and a file logical structure of the present invention.
FIG. 2 is a diagram showing a conventional file system and a file logical structure.
FIG. 3 is a diagram illustrating a conventional file logical structure that guarantees integrity.
[Explanation of symbols]
10 Data Block 11 Block Bitmap File 12 Inode Bitmap File 13 Inode Table File 14 Data Block 15 Root Inode 16 File Logical Structure 17 Inode Table File Logical Structure

Claims (4)

A file system integrity guarantee method for managing a disk storage device by dividing it into logical blocks,
Include multiple files in the lowest layer composed of multiple lowest layer blocks,
Including the hash value and block number of each lowest layer block constituting the file in the i-node which is the logical structure of each file;
Including each i-node in an i-node table file composed of a plurality of middle-layer blocks, and including an inode having a high update frequency and an inode having a low update frequency in another intermediate-layer block,
The root inode which is the logical structure of the i-node table file includes a portion including the hash value and block number of each intermediate layer block and a hash value obtained by applying a keyed one-way function to the portion. ,
File integrity assurance method of system that is characterized in that the inclusion of the route i node to a single top layer block. A computer system capable of realizing a file system for managing a disk storage device by dividing it into logical blocks,
Include multiple files in the lowest layer composed of multiple lowest layer blocks,
Including the hash value and block number of each lowest layer block constituting the file in the i-node which is the logical structure of each file;
Including each i-node in an i-node table file composed of a plurality of middle-layer blocks, and including an inode having a high update frequency and an inode having a low update frequency in another intermediate-layer block,
The root inode which is the logical structure of the i-node table file includes a portion including the hash value and block number of each intermediate layer block and a hash value obtained by applying a keyed one-way function to the portion. ,
The computer system capable of realizing a file system that is characterized in that the inclusion of the route i node to a single top layer block. A file system integrity assurance program for managing a disk storage device by dividing it into logical blocks,
Include multiple files in the lowest layer composed of multiple lowest layer blocks,
Including the hash value and block number of each lowest layer block constituting the file in the i-node which is the logical structure of each file;
Including each i-node in an i-node table file composed of a plurality of middle-layer blocks, and including an inode having a high update frequency and an inode having a low update frequency in another intermediate-layer block,
The root inode which is the logical structure of the i-node table file includes a portion including the hash value and block number of each intermediate layer block and a hash value obtained by applying a keyed one-way function to the portion. ,
Include the root inode in a single top layer block
A program for ensuring the integrity of a file system, which causes a computer to execute 4. A computer-readable recording medium for integrity assurance of a file system, wherein the integrity assurance program for a file system according to claim 3 is recorded.

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