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authoraxtloss <axtlos@getcryst.al>2024-02-28 23:42:26 +0100
committeraxtloss <axtlos@getcryst.al>2024-02-28 23:42:26 +0100
commit3341bd0e945341528033ec6ebaef4f611f654ebe (patch)
treef82d4557ac097d08583e56152352cbd5abd335ea /core/storage.go
parent91d58f9ae9e9d9adc2e19a0b56d2b9757f6696d6 (diff)
downloadfsverify-3341bd0e945341528033ec6ebaef4f611f654ebe.tar.gz
fsverify-3341bd0e945341528033ec6ebaef4f611f654ebe.tar.bz2
restructure repository layout
Diffstat (limited to 'core/storage.go')
-rw-r--r--core/storage.go246
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
-}