Synnefo » snf-ganeti

{-| Implementation of the runtime configuration details.

-}

{-

Copyright (C) 2011, 2012 Google Inc.

This program is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation; either version 2 of the License, or

(at your option) any later version.

This program is distributed in the hope that it will be useful, but

WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

General Public License for more details.

You should have received a copy of the GNU General Public License

along with this program; if not, write to the Free Software

Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

02110-1301, USA.

-}

module Ganeti.Runtime

  ( GanetiDaemon(..)

  , MiscGroup(..)

  , GanetiGroup(..)

  , RuntimeEnts

  , daemonName

  , daemonUser

  , daemonGroup

  , daemonLogFile

  , daemonPidFile

  , getEnts

  , verifyDaemonUser

  ) where

import Control.Exception

import Control.Monad

import qualified Data.Map as M

import System.Exit

import System.FilePath

import System.IO

import System.IO.Error

import System.Posix.Types

import System.Posix.User

import Text.Printf

import qualified Ganeti.Constants as C

import qualified Ganeti.Path as Path

import Ganeti.BasicTypes

data GanetiDaemon = GanetiMasterd

                  | GanetiNoded

                  | GanetiRapi

                  | GanetiConfd

                    deriving (Show, Enum, Bounded, Eq, Ord)

data MiscGroup = DaemonsGroup

               | AdminGroup

                 deriving (Show, Enum, Bounded, Eq, Ord)

data GanetiGroup = DaemonGroup GanetiDaemon

                 | ExtraGroup MiscGroup

                   deriving (Show, Eq, Ord)

type RuntimeEnts = (M.Map GanetiDaemon UserID, M.Map GanetiGroup GroupID)

-- | Returns the daemon name for a given daemon.

daemonName :: GanetiDaemon -> String

daemonName GanetiMasterd = C.masterd

daemonName GanetiNoded   = C.noded

daemonName GanetiRapi    = C.rapi

daemonName GanetiConfd   = C.confd

-- | Returns the configured user name for a daemon.

daemonUser :: GanetiDaemon -> String

daemonUser GanetiMasterd = C.masterdUser

daemonUser GanetiNoded   = C.nodedUser

daemonUser GanetiRapi    = C.rapiUser

daemonUser GanetiConfd   = C.confdUser

-- | Returns the configured group for a daemon.

daemonGroup :: GanetiGroup -> String

daemonGroup (DaemonGroup GanetiMasterd) = C.masterdGroup

daemonGroup (DaemonGroup GanetiNoded)   = C.nodedGroup

daemonGroup (DaemonGroup GanetiRapi)    = C.rapiGroup

daemonGroup (DaemonGroup GanetiConfd)   = C.confdGroup

daemonGroup (ExtraGroup  DaemonsGroup)  = C.daemonsGroup

daemonGroup (ExtraGroup  AdminGroup)    = C.adminGroup

-- | Returns the log file for a daemon.

daemonLogFile :: GanetiDaemon -> FilePath

daemonLogFile daemon = Path.logDir </> daemonName daemon <.> "log"

-- | Returns the pid file name for a daemon.

daemonPidFile :: GanetiDaemon -> FilePath

daemonPidFile daemon = Path.runDir </> daemonName daemon <.> "pid"

-- | All groups list. A bit hacking, as we can't enforce it's complete

-- at compile time.

allGroups :: [GanetiGroup]

allGroups = map DaemonGroup [minBound..maxBound] ++

            map ExtraGroup  [minBound..maxBound]

ignoreDoesNotExistErrors :: IO a -> IO (Result a)

ignoreDoesNotExistErrors value = do

  result <- tryJust (\e -> if isDoesNotExistError e

                             then Just (show e)

                             else Nothing) value

  return $ eitherToResult result

-- | Computes the group/user maps.

getEnts :: IO (Result RuntimeEnts)

getEnts = do

  users <- mapM (\daemon -> do

                   entry <- ignoreDoesNotExistErrors .

                            getUserEntryForName .

                            daemonUser $ daemon

                   return (entry >>= \e -> return (daemon, userID e))

                ) [minBound..maxBound]

  groups <- mapM (\group -> do

                    entry <- ignoreDoesNotExistErrors .

                             getGroupEntryForName .

                             daemonGroup $ group

                    return (entry >>= \e -> return (group, groupID e))

                 ) allGroups

  return $ do -- 'Result' monad

    users'  <- sequence users

    groups' <- sequence groups

    let usermap = M.fromList users'

        groupmap = M.fromList groups'

    return (usermap, groupmap)

-- | Checks whether a daemon runs as the right user.

verifyDaemonUser :: GanetiDaemon -> RuntimeEnts -> IO ()

verifyDaemonUser daemon ents = do

  myuid <- getEffectiveUserID

  -- note: we use directly ! as lookup failues shouldn't happen, due

  -- to the above map construction

  checkUidMatch (daemonName daemon) ((M.!) (fst ents) daemon) myuid

-- | Check that two UIDs are matching or otherwise exit.

checkUidMatch :: String -> UserID -> UserID -> IO ()

checkUidMatch name expected actual =

  when (expected /= actual) $ do

    hPrintf stderr "%s started using wrong user ID (%d), \

                   \expected %d\n" name

              (fromIntegral actual::Int)

              (fromIntegral expected::Int) :: IO ()

    exitWith $ ExitFailure C.exitFailure