From 9c97ec26003581b1b1238b3921b43ba9baaaa80f Mon Sep 17 00:00:00 2001 From: Joey Hess Date: Fri, 25 Mar 2016 17:24:54 -0400 Subject: Avoid generating excessively long paths to the unix socket file used for ssh connection caching. Mostly. Can still generate a too long one if $HOME is longer than 60 bytes. --- src/Propellor/Ssh.hs | 41 ++++++++++++++++++++++++++++++++++++++--- 1 file changed, 38 insertions(+), 3 deletions(-) (limited to 'src') diff --git a/src/Propellor/Ssh.hs b/src/Propellor/Ssh.hs index b00eb651..3e4806ea 100644 --- a/src/Propellor/Ssh.hs +++ b/src/Propellor/Ssh.hs @@ -2,9 +2,11 @@ module Propellor.Ssh where import Propellor.Base import Utility.UserInfo +import Utility.FileSystemEncoding import System.PosixCompat import Data.Time.Clock.POSIX +import qualified Data.Hash.MD5 as MD5 -- Parameters can be passed to both ssh and scp, to enable a ssh connection -- caching socket. @@ -16,9 +18,8 @@ import Data.Time.Clock.POSIX sshCachingParams :: HostName -> IO [CommandParam] sshCachingParams hn = do home <- myHomeDir - let cachedir = home ".ssh" "propellor" - createDirectoryIfMissing False cachedir - let socketfile = cachedir hn ++ ".sock" + let socketfile = socketFile home hn + createDirectoryIfMissing False (takeDirectory socketfile) let ps = [ Param "-o" , Param ("ControlPath=" ++ socketfile) @@ -42,3 +43,37 @@ sshCachingParams hn = do [ Param "localhost" ] nukeFile f tenminutes = 600 + +-- Generate a socket filename inside the home directory. +-- +-- There's a limit in the size of unix domain sockets, of approximately +-- 100 bytes. Try to never construct a filename longer than that. +-- +-- When space allows, include the full hostname in the socket filename. +-- Otherwise, include at least a partial md5sum of it, +-- to avoid using the same socket file for multiple hosts. +socketFile :: FilePath -> HostName -> FilePath +socketFile home hn = selectSocketFile + [ sshdir hn ++ ".sock" + , sshdir hn + , sshdir take 10 hn ++ "-" ++ md5 + , sshdir md5 + , home ".propellor-" ++ md5 + ] + (".propellor-" ++ md5) + where + sshdir = home ".ssh" "propellor" + md5 = take 9 $ MD5.md5s $ MD5.Str hn + +selectSocketFile :: [FilePath] -> FilePath -> FilePath +selectSocketFile [] fallback = fallback +selectSocketFile [f] _ = f +selectSocketFile (f:fs) fallback + | valid_unix_socket_path f = f + | otherwise = selectSocketFile fs fallback + +valid_unix_socket_path :: FilePath -> Bool +valid_unix_socket_path f = length (decodeW8 f) < 100 - reservedbyssh + where + -- ssh tacks on 17 or so characters when making a socket + reservedbyssh = 18 -- cgit v1.2.3