{- git-annex hashing backends - - Copyright 2011-2021 Joey Hess - - Licensed under the GNU AGPL version 3 or higher. -} {-# LANGUAGE OverloadedStrings #-} module Backend.Hash ( backends, testKeyBackend, keyHash, ) where import Annex.Common import qualified Annex import Backend.Utilities import Types.Key import Types.Backend import Types.KeySource import Utility.Hash import Utility.Metered import qualified Utility.RawFilePath as R import qualified Data.ByteString as S import qualified Data.ByteString.Short as S (toShort, fromShort) import qualified Data.ByteString.Char8 as S8 import qualified Data.ByteString.Lazy as L import Control.DeepSeq import Control.Exception (evaluate) data Hash = MD5Hash | SHA1Hash | SHA2Hash HashSize | SHA3Hash HashSize | SkeinHash HashSize | Blake2bHash HashSize | Blake2bpHash HashSize | Blake2sHash HashSize | Blake2spHash HashSize cryptographicallySecure :: Hash -> Bool cryptographicallySecure (SHA2Hash _) = True cryptographicallySecure (SHA3Hash _) = True cryptographicallySecure (SkeinHash _) = True cryptographicallySecure (Blake2bHash _) = True cryptographicallySecure (Blake2bpHash _) = True cryptographicallySecure (Blake2sHash _) = True cryptographicallySecure (Blake2spHash _) = True cryptographicallySecure SHA1Hash = False cryptographicallySecure MD5Hash = False {- Order is slightly significant; want SHA256 first, and more general - sizes earlier. -} hashes :: [Hash] hashes = concat [ map (SHA2Hash . HashSize) [256, 512, 224, 384] , map (SHA3Hash . HashSize) [256, 512, 224, 384] , map (SkeinHash . HashSize) [256, 512] , map (Blake2bHash . HashSize) [256, 512, 160, 224, 384] , map (Blake2bpHash . HashSize) [512] , map (Blake2sHash . HashSize) [256, 160, 224] , map (Blake2spHash . HashSize) [256, 224] , [SHA1Hash] , [MD5Hash] ] {- The SHA256E backend is the default, so genBackendE comes first. -} backends :: [Backend] backends = concatMap (\h -> [genBackendE h, genBackend h]) hashes genBackend :: Hash -> Backend genBackend hash = Backend { backendVariety = hashKeyVariety hash (HasExt False) , genKey = Just (keyValue hash) , verifyKeyContent = Just $ checkKeyChecksum hash , verifyKeyContentIncrementally = Just $ checkKeyChecksumIncremental hash , canUpgradeKey = Just needsUpgrade , fastMigrate = Just trivialMigrate , isStableKey = const True , isCryptographicallySecure = const (cryptographicallySecure hash) } genBackendE :: Hash -> Backend genBackendE hash = (genBackend hash) { backendVariety = hashKeyVariety hash (HasExt True) , genKey = Just (keyValueE hash) } hashKeyVariety :: Hash -> HasExt -> KeyVariety hashKeyVariety MD5Hash he = MD5Key he hashKeyVariety SHA1Hash he = SHA1Key he hashKeyVariety (SHA2Hash size) he = SHA2Key size he hashKeyVariety (SHA3Hash size) he = SHA3Key size he hashKeyVariety (SkeinHash size) he = SKEINKey size he hashKeyVariety (Blake2bHash size) he = Blake2bKey size he hashKeyVariety (Blake2bpHash size) he = Blake2bpKey size he hashKeyVariety (Blake2sHash size) he = Blake2sKey size he hashKeyVariety (Blake2spHash size) he = Blake2spKey size he {- A key is a hash of its contents. -} keyValue :: Hash -> KeySource -> MeterUpdate -> Annex Key keyValue hash source meterupdate = do let file = contentLocation source filesize <- liftIO $ getFileSize file s <- hashFile hash file meterupdate return $ mkKey $ \k -> k { keyName = S.toShort (encodeBS s) , keyVariety = hashKeyVariety hash (HasExt False) , keySize = Just filesize } {- Extension preserving keys. -} keyValueE :: Hash -> KeySource -> MeterUpdate -> Annex Key keyValueE hash source meterupdate = keyValue hash source meterupdate >>= addE source (const $ hashKeyVariety hash (HasExt True)) checkKeyChecksum :: Hash -> Key -> RawFilePath -> Annex Bool checkKeyChecksum hash key file = catchIOErrorType HardwareFault hwfault $ do fast <- Annex.getRead Annex.fast exists <- liftIO $ R.doesPathExist file case (exists, fast) of (True, False) -> do showAction descChecksum sameCheckSum key <$> hashFile hash file nullMeterUpdate _ -> return True where hwfault e = do warning $ "hardware fault: " ++ show e return False sameCheckSum :: Key -> String -> Bool sameCheckSum key s | s == expected = True {- A bug caused checksums to be prefixed with \ in some - cases; still accept these as legal now that the bug - has been fixed. -} | '\\' : s == expected = True | otherwise = False where expected = decodeBS (keyHash key) checkKeyChecksumIncremental :: Hash -> Key -> Annex IncrementalVerifier checkKeyChecksumIncremental hash key = liftIO $ (snd $ hasher hash) key keyHash :: Key -> S.ByteString keyHash = fst . splitKeyNameExtension {- Upgrade keys that have the \ prefix on their hash due to a bug, or - that contain non-alphanumeric characters in their extension. - - Also, for a while migrate from eg SHA256E to SHA256 resulted in a SHA256 - key that contained an extension inside its keyName. Upgrade those - keys, removing the extension. -} needsUpgrade :: Key -> Bool needsUpgrade key = or [ "\\" `S8.isPrefixOf` keyHash key , S.any (not . validInExtension) (snd $ splitKeyNameExtension key) , not (hasExt (fromKey keyVariety key)) && keyHash key /= S.fromShort (fromKey keyName key) ] trivialMigrate :: Key -> Backend -> AssociatedFile -> Annex (Maybe Key) trivialMigrate oldkey newbackend afile = trivialMigrate' oldkey newbackend afile <$> (annexMaxExtensionLength <$> Annex.getGitConfig) trivialMigrate' :: Key -> Backend -> AssociatedFile -> Maybe Int -> Maybe Key trivialMigrate' oldkey newbackend afile maxextlen {- Fast migration from hashE to hash backend. -} | migratable && hasExt oldvariety = Just $ alterKey oldkey $ \d -> d { keyName = S.toShort (keyHash oldkey) , keyVariety = newvariety } {- Fast migration from hash to hashE backend. -} | migratable && hasExt newvariety = case afile of AssociatedFile Nothing -> Nothing AssociatedFile (Just file) -> Just $ alterKey oldkey $ \d -> d { keyName = S.toShort $ keyHash oldkey <> selectExtension maxextlen file , keyVariety = newvariety } {- Upgrade to fix bad previous migration that created a - non-extension preserving key, with an extension - in its keyName. -} | newvariety == oldvariety && not (hasExt oldvariety) && keyHash oldkey /= S.fromShort (fromKey keyName oldkey) = Just $ alterKey oldkey $ \d -> d { keyName = S.toShort (keyHash oldkey) } | otherwise = Nothing where migratable = oldvariety /= newvariety && sameExceptExt oldvariety newvariety oldvariety = fromKey keyVariety oldkey newvariety = backendVariety newbackend hashFile :: Hash -> RawFilePath -> MeterUpdate -> Annex String hashFile hash file meterupdate = liftIO $ withMeteredFile (fromRawFilePath file) meterupdate $ \b -> do let h = (fst $ hasher hash) b -- Force full evaluation of hash so whole file is read -- before returning. evaluate (rnf h) return h type Hasher = (L.ByteString -> String, Key -> IO IncrementalVerifier) hasher :: Hash -> Hasher hasher MD5Hash = md5Hasher hasher SHA1Hash = sha1Hasher hasher (SHA2Hash hashsize) = sha2Hasher hashsize hasher (SHA3Hash hashsize) = sha3Hasher hashsize hasher (SkeinHash hashsize) = skeinHasher hashsize hasher (Blake2bHash hashsize) = blake2bHasher hashsize hasher (Blake2bpHash hashsize) = blake2bpHasher hashsize hasher (Blake2sHash hashsize) = blake2sHasher hashsize hasher (Blake2spHash hashsize) = blake2spHasher hashsize mkHasher :: HashAlgorithm h => (L.ByteString -> Digest h) -> Context h -> Hasher mkHasher h c = (show . h, mkIncrementalVerifier c descChecksum . sameCheckSum) sha2Hasher :: HashSize -> Hasher sha2Hasher (HashSize hashsize) | hashsize == 256 = mkHasher sha2_256 sha2_256_context | hashsize == 224 = mkHasher sha2_224 sha2_224_context | hashsize == 384 = mkHasher sha2_384 sha2_384_context | hashsize == 512 = mkHasher sha2_512 sha2_512_context | otherwise = error $ "unsupported SHA2 size " ++ show hashsize sha3Hasher :: HashSize -> Hasher sha3Hasher (HashSize hashsize) | hashsize == 256 = mkHasher sha3_256 sha3_256_context | hashsize == 224 = mkHasher sha3_224 sha3_224_context | hashsize == 384 = mkHasher sha3_384 sha3_384_context | hashsize == 512 = mkHasher sha3_512 sha3_512_context | otherwise = error $ "unsupported SHA3 size " ++ show hashsize skeinHasher :: HashSize -> Hasher skeinHasher (HashSize hashsize) | hashsize == 256 = mkHasher skein256 skein256_context | hashsize == 512 = mkHasher skein512 skein512_context | otherwise = error $ "unsupported SKEIN size " ++ show hashsize blake2bHasher :: HashSize -> Hasher blake2bHasher (HashSize hashsize) | hashsize == 256 = mkHasher blake2b_256 blake2b_256_context | hashsize == 512 = mkHasher blake2b_512 blake2b_512_context | hashsize == 160 = mkHasher blake2b_160 blake2b_160_context | hashsize == 224 = mkHasher blake2b_224 blake2b_224_context | hashsize == 384 = mkHasher blake2b_384 blake2b_384_context | otherwise = error $ "unsupported BLAKE2B size " ++ show hashsize blake2bpHasher :: HashSize -> Hasher blake2bpHasher (HashSize hashsize) | hashsize == 512 = mkHasher blake2bp_512 blake2bp_512_context | otherwise = error $ "unsupported BLAKE2BP size " ++ show hashsize blake2sHasher :: HashSize -> Hasher blake2sHasher (HashSize hashsize) | hashsize == 256 = mkHasher blake2s_256 blake2s_256_context | hashsize == 160 = mkHasher blake2s_160 blake2s_160_context | hashsize == 224 = mkHasher blake2s_224 blake2s_224_context | otherwise = error $ "unsupported BLAKE2S size " ++ show hashsize blake2spHasher :: HashSize -> Hasher blake2spHasher (HashSize hashsize) | hashsize == 256 = mkHasher blake2sp_256 blake2sp_256_context | hashsize == 224 = mkHasher blake2sp_224 blake2sp_224_context | otherwise = error $ "unsupported BLAKE2SP size " ++ show hashsize sha1Hasher :: Hasher sha1Hasher = mkHasher sha1 sha1_context md5Hasher :: Hasher md5Hasher = mkHasher md5 md5_context descChecksum :: String descChecksum = "checksum" {- A variant of the SHA256E backend, for testing that needs special keys - that cannot collide with legitimate keys in the repository. - - This is accomplished by appending a special extension to the key, - that is not one that selectExtension would select (due to being too - long). -} testKeyBackend :: Backend testKeyBackend = let b = genBackendE (SHA2Hash (HashSize 256)) gk = case genKey b of Nothing -> Nothing Just f -> Just (\ks p -> addTestE <$> f ks p) in b { genKey = gk } where addTestE k = alterKey k $ \d -> d { keyName = keyName d <> longext } longext = ".this-is-a-test-key"