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author | axtloss <axtlos@getcryst.al> | 2024-02-28 23:42:26 +0100 |
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committer | axtloss <axtlos@getcryst.al> | 2024-02-28 23:42:26 +0100 |
commit | 3341bd0e945341528033ec6ebaef4f611f654ebe (patch) | |
tree | f82d4557ac097d08583e56152352cbd5abd335ea /core/storage.go | |
parent | 91d58f9ae9e9d9adc2e19a0b56d2b9757f6696d6 (diff) | |
download | fsverify-3341bd0e945341528033ec6ebaef4f611f654ebe.tar.gz fsverify-3341bd0e945341528033ec6ebaef4f611f654ebe.tar.bz2 |
restructure repository layout
Diffstat (limited to 'core/storage.go')
-rw-r--r-- | core/storage.go | 246 |
1 files changed, 0 insertions, 246 deletions
diff --git a/core/storage.go b/core/storage.go deleted file mode 100644 index 182e1ec..0000000 --- a/core/storage.go +++ /dev/null @@ -1,246 +0,0 @@ -package core - -import ( - "bufio" - "bytes" - "encoding/binary" - "encoding/json" - "fmt" - bolt "go.etcd.io/bbolt" - "io" - "os" -) - -// Header contains all information stored in the header of a fsverify partition. -type Header struct { - MagicNumber int - Signature string - FilesystemSize int - FilesystemUnit int - TableSize int - TableUnit int -} - -// Node contains all information stored in a database node. -// If the Node is the first node in the database, PrevNodeSum should be set to Entrypoint. -type Node struct { - BlockStart int - BlockEnd int - BlockSum string - PrevNodeSum string -} - -// GetHash returns the hash of all fields of a Node combined. -// The Node fields are combined in the order BlockStart, BlockEnd, BlockSum and PrevNodeSum -func (n *Node) GetHash() (string, error) { - return calculateStringHash(fmt.Sprintf("%d%d%s%s", n.BlockStart, n.BlockEnd, n.BlockSum, n.PrevNodeSum)) -} - -// parseUnitSpec parses the file size unit specified in the header and returns it as an according multiplier. -// In the case of an invalid Unit byte the function returns -1. -func parseUnitSpec(size []byte) int { - switch size[0] { - case 0: - return 1 - case 1: - return 1000 - case 2: - return 1000 * 1000 - case 3: - return 1000 * 1000 * 10000 - case 4: - return 100000000000000 - case 5: - return 1000000000000000 - default: - return -1 - } -} - -// ReadHeader reads the partition header and puts it in a variable of type Header. -// If any field fails to be read, the function returns an empty Header struct and the error. -func ReadHeader(partition string) (Header, error) { - _, exist := os.Stat(partition) - if os.IsNotExist(exist) { - return Header{}, fmt.Errorf("Cannot find partition %s", partition) - } - part, err := os.Open(partition) - if err != nil { - return Header{}, err - } - defer part.Close() - - header := Header{} - reader := bufio.NewReader(part) - // Since the size of each field is already known - // it is best to hard code them, in the case - // that a field goes over its allocated size - // fsverify should (and will) fail - MagicNumber := make([]byte, 2) - UntrustedHash := make([]byte, 100) - TrustedHash := make([]byte, 88) - FilesystemSize := make([]byte, 4) - FilesystemUnit := make([]byte, 1) - TableSize := make([]byte, 4) - TableUnit := make([]byte, 1) - - _, err = reader.Read(MagicNumber) - MagicNum := binary.BigEndian.Uint16(MagicNumber) - if MagicNum != 0xACAB { // The Silliest of magic numbers - return Header{}, err - } - header.MagicNumber = int(MagicNum) - - _, err = reader.Read(UntrustedHash) - if err != nil { - return Header{}, err - } - _, err = reader.Read(TrustedHash) - if err != nil { - return Header{}, err - } - _, err = reader.Read(FilesystemSize) - if err != nil { - return Header{}, err - } - _, err = reader.Read(FilesystemUnit) - if err != nil { - return Header{}, err - } - _, err = reader.Read(TableSize) - if err != nil { - return Header{}, err - } - _, err = reader.Read(TableUnit) - if err != nil { - return Header{}, err - } - - header.Signature = fmt.Sprintf("untrusted comment: fsverify\n%s\ntrusted comment: fsverify\n%s\n", string(UntrustedHash), string(TrustedHash)) - header.FilesystemSize = int(binary.BigEndian.Uint32(FilesystemSize)) - header.TableSize = int(binary.BigEndian.Uint32(TableSize)) - header.FilesystemUnit = parseUnitSpec(FilesystemUnit) - header.TableUnit = parseUnitSpec(TableUnit) - if header.FilesystemUnit == -1 || header.TableUnit == -1 { - return Header{}, fmt.Errorf("unit size for Filesystem or Table invalid: fs: %x, table: %x", FilesystemUnit, TableUnit) - } - return header, nil -} - -// ReadDB reads the database from a fsverify partition. -// It verifies the the size of the database with the size specified in the partition header and returns an error if the sizes do not match. -// Due to limitations with bbolt the database gets written to a temporary path and the function returns the path to the database. -func ReadDB(partition string) (string, error) { - _, exist := os.Stat(partition) - if os.IsNotExist(exist) { - return "", fmt.Errorf("Cannot find partition %s", partition) - } - part, err := os.Open(partition) - if err != nil { - return "", err - } - defer part.Close() - reader := bufio.NewReader(part) - - // The area taken up by the header - // it is useless for this reader instance - // and will be skipped completely - _, err = reader.Read(make([]byte, 200)) - if err != nil { - fmt.Println(err) - return "", err - } - - header, err := ReadHeader(partition) - if err != nil { - fmt.Println(err) - return "", err - } - - // Reading the specified table size allows for tamper protection - // in the case that the partition was tampered with "lazily" - // meaning that only the database was modified, and not the header - // if that is the case, the database would be lacking data, making it unusable - db := make([]byte, header.TableSize*header.TableUnit) - n, err := io.ReadFull(reader, db) - if err != nil { - return "", err - } - if n != header.TableSize*header.TableUnit { - return "", fmt.Errorf("Database is not expected size. Expected %d, got %d", header.TableSize*header.TableUnit, n) - } - fmt.Printf("db: %d\n", n) - - // Write the database to a temporary directory - // to ensure that it disappears after the next reboot - temp, err := os.MkdirTemp("", "*-fsverify") - if err != nil { - return "", err - } - - // The file permission is immediately set to 0700 - // this ensures that the database is not modified - // after it has been written - err = os.WriteFile(temp+"/verify.db", db, 0700) - if err != nil { - return "", err - } - - return temp + "/verify.db", nil -} - -// OpenDB opens a bbolt database and returns a bbolt instance. -func OpenDB(dbpath string, readonly bool) (*bolt.DB, error) { - _, exist := os.Stat(dbpath) - if os.IsNotExist(exist) { - os.Create(dbpath) - } - db, err := bolt.Open(dbpath, 0777, &bolt.Options{ReadOnly: readonly}) - if err != nil { - return nil, err - } - return db, nil -} - -// GetNode retrieves a Node from the database based on the hash identifier. -// If db is set to nil, the function will open the database in read-only mode itself. -func GetNode(checksum string, db *bolt.DB) (Node, error) { - var err error - var deferDB bool - if db == nil { - db, err = OpenDB("my.db", true) - if err != nil { - return Node{}, err - } - deferDB = true - } - var node Node - err = db.View(func(tx *bolt.Tx) error { - nodes := tx.Bucket([]byte("Nodes")) - app := nodes.Get([]byte(checksum)) - err := json.Unmarshal(app, &node) - return err - }) - if deferDB { - defer db.Close() - } - return node, err -} - -// CopyByteArea copies an area of bytes from a reader. -// It verifies that the reader reads the wanted amount of bytes, and returns an error if this is not the case. -func CopyByteArea(start int, end int, reader *bytes.Reader) ([]byte, error) { - if end-start < 0 { - return []byte{}, fmt.Errorf("tried creating byte slice with negative length. %d to %d total %d\n", start, end, end-start) - } else if end-start > 2000 { - return []byte{}, fmt.Errorf("tried creating byte slice with length over 2000. %d to %d total %d\n", start, end, end-start) - } - bytes := make([]byte, end-start) - n, err := reader.ReadAt(bytes, int64(start)) - if err != nil { - return nil, err - } else if n != end-start { - return nil, fmt.Errorf("Unable to read requested size. Expected %d, got %d", end-start, n) - } - return bytes, nil -} |