15be5c04a6
The attacker could just send a very lot of data, with no \n and it would all be buffered in memory until the kernel killed git-annex or perhaps OOM killed some other more valuable process. This is a low impact security hole, only affecting communication between local git-annex and git-annex-shell on the remote system. (With either able to be the attacker). Only those with the right ssh key can do it. And, there are probably lots of ways to construct git repositories that make git use a lot of memory in various ways, which would have similar impact as this attack. The fix in P2P/IO.hs would have been higher impact, if it had made it to a released version, since it would have allowed DOSing the tor hidden service without needing to authenticate. (The LockContent and NotifyChanges instances may not be really exploitable; since the line is read and ignored, it probably gets read lazily and does not end up staying buffered in memory.)
45 lines
1.1 KiB
Haskell
45 lines
1.1 KiB
Haskell
{- git-annex-shell command
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-
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- Copyright 2015 Joey Hess <id@joeyh.name>
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-
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- Licensed under the GNU GPL version 3 or higher.
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-}
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module Command.LockContent where
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import Command
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import Annex.Content
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import Remote.Helper.Ssh (contentLockedMarker)
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import Utility.SimpleProtocol
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cmd :: Command
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cmd = noCommit $
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command "lockcontent" SectionPlumbing
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"locks key's content in the annex, preventing it being dropped"
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paramKey
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(withParams seek)
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seek :: CmdParams -> CommandSeek
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seek = withWords start
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-- First, lock the content. Then, make sure the content is actually
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-- present, and print out "OK". Wait for the caller to send a line before
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-- dropping the lock.
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start :: [String] -> CommandStart
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start [ks] = do
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ok <- lockContentShared k (const locksuccess)
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`catchNonAsync` (const $ return False)
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liftIO $ if ok
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then exitSuccess
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else exitFailure
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where
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k = fromMaybe (giveup "bad key") (file2key ks)
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locksuccess = ifM (inAnnex k)
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( liftIO $ do
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putStrLn contentLockedMarker
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hFlush stdout
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_ <- getProtocolLine stdin
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return True
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, return False
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)
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start _ = giveup "Specify exactly 1 key."
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