glacier, S3: Fix bug that caused embedded creds to not be encypted using the remote's key.

encryptionSetup must be called before setRemoteCredPair. Otherwise,
the RemoteConfig doesn't have the cipher in it, and so no cipher is used to
encrypt the embedded creds.

This is a security fix for non-shared encryption methods!

For encryption=shared, there's no security problem, just an
inconsistentency in whether the embedded creds are encrypted.

This is very important to get right, so used some types to help ensure that
setRemoteCredPair is only run after encryptionSetup. Note that the external
special remote bypasses the type safety, since creds can be set after the
initial remote config, if the external special remote program requests it.
Also note that IA remotes never use encryption, so encryptionSetup is not
run for them at all, and again the type safety is bypassed.

This leaves two open questions:

1. What to do about S3 and glacier remotes that were set up
   using encryption=pubkey/hybrid with embedcreds?
   Such a git repo has a security hole embedded in it, and this needs to be
   communicated to the user. Is the changelog enough?

2. enableremote won't work in such a repo, because git-annex will
   try to decrypt the embedded creds, which are not encrypted, so fails.
   This needs to be dealt with, especially for ecryption=shared repos,
   which are not really broken, just inconsistently configured.

   Noticing that problem for encryption=shared is what led to commit
   fbdeeeed5f, which tried to
   fix the problem by not decrypting the embedded creds.

This commit was sponsored by Josh Taylor.

Creds.hs

@@ -23,7 +23,7 @@ import Annex.Perms
 import Utility.FileMode
 import Crypto
 import Types.Remote (RemoteConfig, RemoteConfigKey)
-import Remote.Helper.Encryptable (remoteCipher, embedCreds)
+import Remote.Helper.Encryptable (remoteCipher, embedCreds, EncryptionIsSetup)
 import Utility.Env (getEnv)
 
 import qualified Data.ByteString.Lazy.Char8 as L
@@ -40,12 +40,17 @@ data CredPairStorage = CredPairStorage
 
 {- Stores creds in a remote's configuration, if the remote allows
  - that. Otherwise, caches them locally.
- - The creds are found in storage if not provided. -}
-setRemoteCredPair :: RemoteConfig -> CredPairStorage -> Maybe CredPair -> Annex RemoteConfig
-setRemoteCredPair c storage Nothing = 
-	maybe (return c) (setRemoteCredPair c storage . Just)
+ - The creds are found in storage if not provided.
+ -
+ - The remote's configuration should have already had a cipher stored in it
+ - if that's going to be done, so that the creds can be encrypted using the
+ - cipher. The EncryptionIsSetup phantom type ensures that is the case.
+ -}
+setRemoteCredPair :: EncryptionIsSetup -> RemoteConfig -> CredPairStorage -> Maybe CredPair -> Annex RemoteConfig
+setRemoteCredPair encsetup c storage Nothing = 
+	maybe (return c) (setRemoteCredPair encsetup c storage . Just)
 		=<< getRemoteCredPair c storage
-setRemoteCredPair c storage (Just creds)
+setRemoteCredPair _ c storage (Just creds)
 	| embedCreds c = case credPairRemoteKey storage of
 		Nothing -> localcache
 		Just key -> storeconfig key =<< remoteCipher c

Remote/Bup.hs

@@ -94,7 +94,7 @@ bupSetup mu _ c = do
 	-- verify configuration is sane
 	let buprepo = fromMaybe (error "Specify buprepo=") $
 		M.lookup "buprepo" c
-	c' <- encryptionSetup c
+	(c', _encsetup) <- encryptionSetup c
 
 	-- bup init will create the repository.
 	-- (If the repository already exists, bup init again appears safe.)

Remote/Ddar.hs

@@ -84,7 +84,7 @@ ddarSetup mu _ c = do
 	-- verify configuration is sane
 	let ddarrepo = fromMaybe (error "Specify ddarrepo=") $
 		M.lookup "ddarrepo" c
-	c' <- encryptionSetup c
+	(c', _encsetup) <- encryptionSetup c
 
 	-- The ddarrepo is stored in git config, as well as this repo's
 	-- persistant state, so it can vary between hosts.

Remote/Directory.hs

@@ -81,7 +81,7 @@ directorySetup mu _ c = do
 	absdir <- liftIO $ absPath dir
 	liftIO $ unlessM (doesDirectoryExist absdir) $
 		error $ "Directory does not exist: " ++ absdir
-	c' <- encryptionSetup c
+	(c', _encsetup) <- encryptionSetup c
 
 	-- The directory is stored in git config, not in this remote's
 	-- persistant state, so it can vary between hosts.

Remote/External.hs

@@ -77,7 +77,7 @@ externalSetup mu _ c = do
 	u <- maybe (liftIO genUUID) return mu
 	let externaltype = fromMaybe (error "Specify externaltype=") $
 		M.lookup "externaltype" c
-	c' <- encryptionSetup c
+	(c', _encsetup) <- encryptionSetup c
 
 	external <- newExternal externaltype u c'
 	handleRequest external INITREMOTE Nothing $ \resp -> case resp of
@@ -191,7 +191,7 @@ handleRequest' lck external req mp responsehandler
 		send $ VALUE value
 	handleRemoteRequest (SETCREDS setting login password) = do
 		c <- liftIO $ atomically $ readTMVar $ externalConfig external
-		c' <- setRemoteCredPair c (credstorage setting) $
+		c' <- setRemoteCredPair encryptionAlreadySetup c (credstorage setting) $
 			Just (login, password)
 		void $ liftIO $ atomically $ swapTMVar (externalConfig external) c'
 	handleRemoteRequest (GETCREDS setting) = do

Remote/GCrypt.hs

@@ -168,7 +168,7 @@ gCryptSetup mu _ c = go $ M.lookup "gitrepo" c
 	remotename = fromJust (M.lookup "name" c)
   	go Nothing = error "Specify gitrepo="
 	go (Just gitrepo) = do
-		c' <- encryptionSetup c
+		(c', _encsetup) <- encryptionSetup c
 		inRepo $ Git.Command.run 
 			[ Params "remote add"
 			, Param remotename

Remote/Glacier.hs

@@ -76,12 +76,12 @@ gen r u c gc = new <$> remoteCost gc veryExpensiveRemoteCost
 glacierSetup :: Maybe UUID -> Maybe CredPair -> RemoteConfig -> Annex (RemoteConfig, UUID)
 glacierSetup mu mcreds c = do
 	u <- maybe (liftIO genUUID) return mu
-	c' <- setRemoteCredPair c (AWS.creds u) mcreds
-	glacierSetup' (isJust mu) u c'
-glacierSetup' :: Bool -> UUID -> RemoteConfig -> Annex (RemoteConfig, UUID)
-glacierSetup' enabling u c = do
-	c' <- encryptionSetup c
-	let fullconfig = c' `M.union` defaults
+	glacierSetup' (isJust mu) u mcreds c
+glacierSetup' :: Bool -> UUID -> Maybe CredPair -> RemoteConfig -> Annex (RemoteConfig, UUID)
+glacierSetup' enabling u mcreds c = do
+	(c', encsetup) <- encryptionSetup c
+	c'' <- setRemoteCredPair encsetup c' (AWS.creds u) mcreds
+	let fullconfig = c'' `M.union` defaults
 	unless enabling $
 		genVault fullconfig u
 	gitConfigSpecialRemote u fullconfig "glacier" "true"

Remote/Helper/Encryptable.hs

@@ -5,7 +5,17 @@
  - Licensed under the GNU GPL version 3 or higher.
  -}
 
-module Remote.Helper.Encryptable where
+module Remote.Helper.Encryptable (
+	EncryptionIsSetup,
+	encryptionSetup,
+	noEncryptionUsed,
+	encryptionAlreadySetup,
+	remoteCipher,
+	embedCreds,
+	cipherKey,
+	storeCipher,
+	extractCipher,
+) where
 
 import qualified Data.Map as M
 
@@ -16,11 +26,26 @@ import Types.Crypto
 import qualified Annex
 import Utility.Base64
 
+-- Used to ensure that encryption has been set up before trying to
+-- eg, store creds in the remote config that would need to use the
+-- encryption setup.
+data EncryptionIsSetup = EncryptionIsSetup | NoEncryption
+
+-- Remotes that don't use encryption can use this instead of
+-- encryptionSetup.
+noEncryptionUsed :: EncryptionIsSetup
+noEncryptionUsed = NoEncryption
+
+-- Using this avoids the type-safe check, so you'd better be sure
+-- of what you're doing.
+encryptionAlreadySetup :: EncryptionIsSetup
+encryptionAlreadySetup = EncryptionIsSetup
+
 {- 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 :: RemoteConfig -> Annex (RemoteConfig, EncryptionIsSetup)
 encryptionSetup c = maybe genCipher updateCipher $ extractCipher c
   where
 	-- The type of encryption
@@ -28,7 +53,7 @@ encryptionSetup c = maybe genCipher updateCipher $ extractCipher c
 	-- Generate a new cipher, depending on the chosen encryption scheme
 	genCipher = case encryption of
 		_ | M.member "cipher" c || M.member "cipherkeys" c -> cannotchange
-		Just "none" -> return c
+		Just "none" -> return (c, NoEncryption)
 		Just "shared" -> use "encryption setup" . genSharedCipher
 			=<< highRandomQuality
 		-- hybrid encryption is the default when a keyid is
@@ -48,7 +73,7 @@ encryptionSetup c = maybe genCipher updateCipher $ extractCipher c
 	cannotchange = error "Cannot set encryption type of existing remotes."
 	-- Update an existing cipher if possible.
 	updateCipher v = case v of
-		SharedCipher _ | maybe True (== "shared") encryption -> return c'
+		SharedCipher _ | maybe True (== "shared") encryption -> return (c', EncryptionIsSetup)
 		EncryptedCipher _ variant _
 			| maybe True (== if variant == Hybrid then "hybrid" else "pubkey") encryption ->
 				use "encryption update" $ updateEncryptedCipher newkeys v
@@ -57,7 +82,7 @@ encryptionSetup c = maybe genCipher updateCipher $ extractCipher c
 		showNote m
 		cipher <- liftIO a
 		showNote $ describeCipher cipher
-		return $ storeCipher c' cipher
+		return (storeCipher c' cipher, EncryptionIsSetup)
 	highRandomQuality = 
 		(&&) (maybe True ( /= "false") $ M.lookup "highRandomQuality" c)
 			<$> fmap not (Annex.getState Annex.fast)

Remote/Hook.hs

@@ -70,7 +70,7 @@ hookSetup mu _ c = do
 	u <- maybe (liftIO genUUID) return mu
 	let hooktype = fromMaybe (error "Specify hooktype=") $
 		M.lookup "hooktype" c
-	c' <- encryptionSetup c
+	(c', _encsetup) <- encryptionSetup c
 	gitConfigSpecialRemote u c' "hooktype" hooktype
 	return (c', u)
 

Remote/Rsync.hs

@@ -138,7 +138,7 @@ rsyncSetup mu _ c = do
 	-- verify configuration is sane
 	let url = fromMaybe (error "Specify rsyncurl=") $
 		M.lookup "rsyncurl" c
-	c' <- encryptionSetup c
+	(c', _encsetup) <- encryptionSetup c
 
 	-- The rsyncurl is stored in git config, not only in this remote's
 	-- persistant state, so it can vary between hosts.

Remote/S3.hs

@@ -77,10 +77,9 @@ gen r u c gc = new <$> remoteCost gc expensiveRemoteCost
 s3Setup :: Maybe UUID -> Maybe CredPair -> RemoteConfig -> Annex (RemoteConfig, UUID)
 s3Setup mu mcreds c = do
 	u <- maybe (liftIO genUUID) return mu
-	c' <- setRemoteCredPair c (AWS.creds u) mcreds
-	s3Setup' u c'
-s3Setup' :: UUID -> RemoteConfig -> Annex (RemoteConfig, UUID)
-s3Setup' u c = if isIA c then archiveorg else defaulthost
+	s3Setup' u mcreds c
+s3Setup' :: UUID -> Maybe CredPair -> RemoteConfig -> Annex (RemoteConfig, UUID)
+s3Setup' u mcreds c = if isIA c then archiveorg else defaulthost
   where
 	remotename = fromJust (M.lookup "name" c)
 	defbucket = remotename ++ "-" ++ fromUUID u
@@ -97,13 +96,15 @@ s3Setup' u c = if isIA c then archiveorg else defaulthost
 		return (fullconfig, u)
 
 	defaulthost = do
-		c' <- encryptionSetup c
-		let fullconfig = c' `M.union` defaults
+		(c', encsetup) <- encryptionSetup c
+		c'' <- setRemoteCredPair encsetup c' (AWS.creds u) mcreds
+		let fullconfig = c'' `M.union` defaults
 		genBucket fullconfig u
 		use fullconfig
 
 	archiveorg = do
 		showNote "Internet Archive mode"
+		void $ setRemoteCredPair noEncryptionUsed c (AWS.creds u) mcreds
 		-- Ensure user enters a valid bucket name, since
 		-- this determines the name of the archive.org item.
 		let bucket = replace " " "-" $ map toLower $

Remote/WebDAV.hs

@@ -81,11 +81,11 @@ webdavSetup mu mcreds c = do
 	url <- case M.lookup "url" c of
 		Nothing -> error "Specify url="
 		Just url -> return url
-	c' <- encryptionSetup c
+	(c', encsetup) <- encryptionSetup c
 	creds <- maybe (getCreds c' u) (return . Just) mcreds
 	testDav url creds
 	gitConfigSpecialRemote u c' "webdav" "true"
-	c'' <- setRemoteCredPair c' (davCreds u) creds
+	c'' <- setRemoteCredPair encsetup c' (davCreds u) creds
 	return (c'', u)
 
 -- Opens a http connection to the DAV server, which will be reused

debian/changelog

@@ -1,5 +1,8 @@
 git-annex (5.20140916) UNRELEASED; urgency=medium
 
+  * Security fix for S3 and glacier when using embedcreds=yes with
+    encryption=pubkey or encryption=hybrid. 
+    The creds embedded in the git repo were *not* encrypted.
   * assistant: Detect when repository has been deleted or moved, and
     automatically shut down the assistant. Closes: #761261
   * Windows: Avoid crashing trying to list gpg secret keys, for gcrypt
@@ -8,8 +11,6 @@ git-annex (5.20140916) UNRELEASED; urgency=medium
     (Bug introduced in version 5.20140817.)
   * add: In direct mode, adding an annex symlink will check it into git,
     as was already done in indirect mode.
-  * Fix reversion in handling creds with encryption=shared embedcreds=yes
-    introduced in 5.20140817.
 
  -- Joey Hess <joeyh@debian.org>  Mon, 15 Sep 2014 14:39:17 -0400
 

doc/bugs/box.com.mdwn

@@ -31,5 +31,3 @@ Mac OS X 10.9.4
 
 # End of transcript or log.
 """]]
-
-> [[fixed|done]] --[[Joey]]