git-annex/Remote/Helper/Encryptable.hs
Joey Hess 9e11699c76 connect existing meters to the transfer log for downloads
Most remotes have meters in their implementations of retrieveKeyFile
already. Simply hooking these up to the transfer log makes that information
available. Easy peasy.

This is particularly valuable information for encrypted remotes, which
otherwise bypass the assistant's polling of temp files, and so don't have
good progress bars yet.

Still some work to do here (see progressbars.mdwn changes), but this
is entirely an improvement from the lack of progress bars for encrypted
downloads.
2013-04-11 17:32:31 -04:00

136 lines
4.9 KiB
Haskell

{- common functions for encryptable remotes
-
- Copyright 2011 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Remote.Helper.Encryptable where
import qualified Data.Map as M
import Common.Annex
import Types.Remote
import Crypto
import Types.Crypto
import qualified Annex
import Config.Cost
import Utility.Base64
import Utility.Metered
{- Encryption setup for a remote. The user must specify whether to use
- an encryption key, or not encrypt. An encrypted cipher is created, or is
- updated to be accessible to an additional encryption key. Or the user
- could opt to use a shared cipher, which is stored unencrypted. -}
encryptionSetup :: RemoteConfig -> Annex RemoteConfig
encryptionSetup c = case (M.lookup "encryption" c, extractCipher c) of
(Nothing, Nothing) -> error "Specify encryption=key or encryption=none or encryption=shared"
(Just "none", Nothing) -> return c
(Nothing, Just _) -> return c
(Just "shared", Just (SharedCipher _)) -> return c
(Just "none", Just _) -> cannotchange
(Just "shared", Just (EncryptedCipher _ _)) -> cannotchange
(Just _, Just (SharedCipher _)) -> cannotchange
(Just "shared", Nothing) -> use "encryption setup" . genSharedCipher
=<< highRandomQuality
(Just keyid, Nothing) -> use "encryption setup" . genEncryptedCipher keyid
=<< highRandomQuality
(Just keyid, Just v) -> use "encryption updated" $ updateEncryptedCipher keyid v
where
cannotchange = error "Cannot change encryption type of existing remote."
use m a = do
cipher <- liftIO a
showNote $ m ++ " " ++ describeCipher cipher
return $ M.delete "encryption" $ M.delete "highRandomQuality" $
storeCipher c cipher
highRandomQuality =
(&&) (maybe True ( /= "false") $ M.lookup "highRandomQuality" c)
<$> fmap not (Annex.getState Annex.fast)
{- Modifies a Remote to support encryption.
-
- Two additional functions must be provided by the remote,
- to support storing and retrieving encrypted content. -}
encryptableRemote
:: RemoteConfig
-> ((Cipher, Key) -> Key -> MeterUpdate -> Annex Bool)
-> ((Cipher, Key) -> Key -> FilePath -> MeterUpdate -> Annex Bool)
-> Remote
-> Remote
encryptableRemote c storeKeyEncrypted retrieveKeyFileEncrypted r =
r {
storeKey = store,
retrieveKeyFile = retrieve,
retrieveKeyFileCheap = retrieveCheap,
removeKey = withkey $ removeKey r,
hasKey = withkey $ hasKey r,
cost = cost r + encryptedRemoteCostAdj
}
where
store k f p = cip k >>= maybe
(storeKey r k f p)
(\enck -> storeKeyEncrypted enck k p)
retrieve k f d p = cip k >>= maybe
(retrieveKeyFile r k f d p)
(\enck -> retrieveKeyFileEncrypted enck k d p)
retrieveCheap k d = cip k >>= maybe
(retrieveKeyFileCheap r k d)
(\_ -> return False)
withkey a k = cip k >>= maybe (a k) (a . snd)
cip = cipherKey c
{- Gets encryption Cipher. The decrypted Ciphers are cached in the Annex
- state. -}
remoteCipher :: RemoteConfig -> Annex (Maybe Cipher)
remoteCipher c = go $ extractCipher c
where
go Nothing = return Nothing
go (Just encipher) = do
cache <- Annex.getState Annex.ciphers
case M.lookup encipher cache of
Just cipher -> return $ Just cipher
Nothing -> do
showNote "gpg"
cipher <- liftIO $ decryptCipher encipher
Annex.changeState (\s -> s { Annex.ciphers = M.insert encipher cipher cache })
return $ Just cipher
{- Checks if the remote's config allows storing creds in the remote's config.
-
- embedcreds=yes allows this, and embedcreds=no prevents it.
-
- If not set, the default is to only store creds when it's surely safe:
- When gpg encryption is used, in which case the creds will be encrypted
- using it. Not when a shared cipher is used.
-}
embedCreds :: RemoteConfig -> Bool
embedCreds c
| M.lookup "embedcreds" c == Just "yes" = True
| M.lookup "embedcreds" c == Just "no" = False
| isJust (M.lookup "cipherkeys" c) && isJust (M.lookup "cipher" c) = True
| otherwise = False
{- Gets encryption Cipher, and encrypted version of Key. -}
cipherKey :: RemoteConfig -> Key -> Annex (Maybe (Cipher, Key))
cipherKey c k = maybe Nothing make <$> remoteCipher c
where
make ciphertext = Just (ciphertext, encryptKey mac ciphertext k)
mac = fromMaybe defaultMac $ M.lookup "mac" c >>= readMac
{- Stores an StorableCipher in a remote's configuration. -}
storeCipher :: RemoteConfig -> StorableCipher -> RemoteConfig
storeCipher c (SharedCipher t) = M.insert "cipher" (toB64 t) c
storeCipher c (EncryptedCipher t ks) =
M.insert "cipher" (toB64 t) $ M.insert "cipherkeys" (showkeys ks) c
where
showkeys (KeyIds l) = join "," l
{- Extracts an StorableCipher from a remote's configuration. -}
extractCipher :: RemoteConfig -> Maybe StorableCipher
extractCipher c =
case (M.lookup "cipher" c, M.lookup "cipherkeys" c) of
(Just t, Just ks) -> Just $ EncryptedCipher (fromB64 t) (readkeys ks)
(Just t, Nothing) -> Just $ SharedCipher (fromB64 t)
_ -> Nothing
where
readkeys = KeyIds . split ","