From c1aec2ae837c24b602c7a0ca3fc7b0fcad565758 Mon Sep 17 00:00:00 2001 From: Joey Hess Date: Thu, 17 Aug 2017 22:11:31 -0400 Subject: avoid the dashed ssh hostname class of security holes Security fix: Disallow hostname starting with a dash, which would get passed to ssh and be treated an option. This could be used by an attacker who provides a crafted ssh url (for eg a git remote) to execute arbitrary code via ssh -oProxyCommand. No CVE has yet been assigned for this hole. The same class of security hole recently affected git itself, CVE-2017-1000117. Method: Identified all places where ssh is run, by git grep '"ssh"' Converted them all to use a SshHost, if they did not already, for specifying the hostname. SshHost was made a data type with a smart constructor, which rejects hostnames starting with '-'. Note that git-annex already contains extensive use of Utility.SafeCommand, which fixes a similar class of problem where a filename starting with a dash gets passed to a program which treats it as an option. This commit was sponsored by Jochen Bartl on Patreon. --- Remote/Rsync.hs | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'Remote/Rsync.hs') diff --git a/Remote/Rsync.hs b/Remote/Rsync.hs index 681052e68..4fc55d725 100644 --- a/Remote/Rsync.hs +++ b/Remote/Rsync.hs @@ -38,6 +38,7 @@ import Types.Transfer import Types.Creds import Annex.DirHashes import Utility.Tmp +import Utility.SshHost import qualified Data.Map as M @@ -120,7 +121,8 @@ rsyncTransport gc url case fromNull ["ssh"] (remoteAnnexRsyncTransport gc) of "ssh":sshopts -> do let (port, sshopts') = sshReadPort sshopts - userhost = takeWhile (/=':') url + userhost = either error id $ mkSshHost $ + takeWhile (/= ':') url (Param "ssh":) <$> sshOptions ConsumeStdin (userhost, port) gc (map Param $ loginopt ++ sshopts') -- cgit v1.2.3