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{-| Implementation of the runtime configuration details.
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-}
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{-
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Copyright (C) 2011, 2012 Google Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301, USA.
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-}
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module Ganeti.Runtime
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  ( GanetiDaemon(..)
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  , MiscGroup(..)
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  , GanetiGroup(..)
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  , RuntimeEnts
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  , daemonName
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  , daemonUser
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  , daemonGroup
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  , daemonLogFile
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  , daemonPidFile
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  , getEnts
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  , verifyDaemonUser
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  ) where
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import Control.Exception
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import Control.Monad
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import qualified Data.Map as M
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import System.Exit
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import System.FilePath
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import System.IO
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import System.IO.Error
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import System.Posix.Types
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import System.Posix.User
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import Text.Printf
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import qualified Ganeti.Constants as C
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import qualified Ganeti.Path as Path
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import Ganeti.BasicTypes
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data GanetiDaemon = GanetiMasterd
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                  | GanetiNoded
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                  | GanetiRapi
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                  | GanetiConfd
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                    deriving (Show, Enum, Bounded, Eq, Ord)
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data MiscGroup = DaemonsGroup
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               | AdminGroup
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                 deriving (Show, Enum, Bounded, Eq, Ord)
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data GanetiGroup = DaemonGroup GanetiDaemon
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                 | ExtraGroup MiscGroup
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                   deriving (Show, Eq, Ord)
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type RuntimeEnts = (M.Map GanetiDaemon UserID, M.Map GanetiGroup GroupID)
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-- | Returns the daemon name for a given daemon.
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daemonName :: GanetiDaemon -> String
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daemonName GanetiMasterd = C.masterd
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daemonName GanetiNoded   = C.noded
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daemonName GanetiRapi    = C.rapi
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daemonName GanetiConfd   = C.confd
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-- | Returns the configured user name for a daemon.
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daemonUser :: GanetiDaemon -> String
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daemonUser GanetiMasterd = C.masterdUser
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daemonUser GanetiNoded   = C.nodedUser
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daemonUser GanetiRapi    = C.rapiUser
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daemonUser GanetiConfd   = C.confdUser
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-- | Returns the configured group for a daemon.
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daemonGroup :: GanetiGroup -> String
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daemonGroup (DaemonGroup GanetiMasterd) = C.masterdGroup
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daemonGroup (DaemonGroup GanetiNoded)   = C.nodedGroup
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daemonGroup (DaemonGroup GanetiRapi)    = C.rapiGroup
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daemonGroup (DaemonGroup GanetiConfd)   = C.confdGroup
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daemonGroup (ExtraGroup  DaemonsGroup)  = C.daemonsGroup
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daemonGroup (ExtraGroup  AdminGroup)    = C.adminGroup
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-- | Returns the log file for a daemon.
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daemonLogFile :: GanetiDaemon -> FilePath
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daemonLogFile daemon = Path.logDir </> daemonName daemon <.> "log"
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-- | Returns the pid file name for a daemon.
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daemonPidFile :: GanetiDaemon -> FilePath
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daemonPidFile daemon = Path.runDir </> daemonName daemon <.> "pid"
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-- | All groups list. A bit hacking, as we can't enforce it's complete
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-- at compile time.
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allGroups :: [GanetiGroup]
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allGroups = map DaemonGroup [minBound..maxBound] ++
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            map ExtraGroup  [minBound..maxBound]
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ignoreDoesNotExistErrors :: IO a -> IO (Result a)
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ignoreDoesNotExistErrors value = do
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  result <- tryJust (\e -> if isDoesNotExistError e
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                             then Just (show e)
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                             else Nothing) value
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  return $ eitherToResult result
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-- | Computes the group/user maps.
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getEnts :: IO (Result RuntimeEnts)
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getEnts = do
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  users <- mapM (\daemon -> do
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                   entry <- ignoreDoesNotExistErrors .
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                            getUserEntryForName .
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                            daemonUser $ daemon
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                   return (entry >>= \e -> return (daemon, userID e))
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                ) [minBound..maxBound]
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  groups <- mapM (\group -> do
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                    entry <- ignoreDoesNotExistErrors .
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                             getGroupEntryForName .
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                             daemonGroup $ group
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                    return (entry >>= \e -> return (group, groupID e))
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                 ) allGroups
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  return $ do -- 'Result' monad
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    users'  <- sequence users
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    groups' <- sequence groups
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    let usermap = M.fromList users'
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        groupmap = M.fromList groups'
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    return (usermap, groupmap)
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-- | Checks whether a daemon runs as the right user.
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verifyDaemonUser :: GanetiDaemon -> RuntimeEnts -> IO ()
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verifyDaemonUser daemon ents = do
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  myuid <- getEffectiveUserID
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  -- note: we use directly ! as lookup failues shouldn't happen, due
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  -- to the above map construction
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  checkUidMatch (daemonName daemon) ((M.!) (fst ents) daemon) myuid
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-- | Check that two UIDs are matching or otherwise exit.
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checkUidMatch :: String -> UserID -> UserID -> IO ()
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checkUidMatch name expected actual =
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  when (expected /= actual) $ do
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    hPrintf stderr "%s started using wrong user ID (%d), \
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                   \expected %d\n" name
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              (fromIntegral actual::Int)
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              (fromIntegral expected::Int) :: IO ()
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    exitWith $ ExitFailure C.exitFailure