Date: Fri, 13 May 2005 12:00:22 GMT From: Giorgos Keramidas <keramida@freebsd.org> To: freebsd-bugs@FreeBSD.org Subject: Re: conf/80907: tmpmfs default change Message-ID: <200505131200.j4DC0M6P003179@freefall.freebsd.org>
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The following reply was made to PR conf/80907; it has been noted by GNATS. From: Giorgos Keramidas <keramida@freebsd.org> To: aeonflux <aeonflux@aeonflux.no-ip.com> Cc: bug-followup@freebsd.org Subject: Re: conf/80907: tmpmfs default change Date: Fri, 13 May 2005 14:55:59 +0300 On 2005-05-12 17:10, aeonflux <aeonflux@aeonflux.no-ip.com> wrote: >On May 12, 2005 09:59 am, Giorgos Keramidas wrote: >> On 2005-05-11 17:38, Caitlen <aeonflux@aeonflux.no-ip.com> wrote: >> > by default >> > tmpmfs_flags="-S" >> > When in reality >> > tmpmfs_flags="-S -o nosymfollow,nosuid" >> > >> > would be much safer >> >> I don't think this is really a bug, but anyway. It would probably be >> safer to use: >> >> tmpmfs_flags="-S -o noatime,noexec,nosuid,nosymfollow" >> >> The ability to actually *use* whatever options are best for your system >> is exactly why I made the original change to rc.d/tmp, but I'm not sure >> if it would be good to enforce so strict permissions to everyone :-/ > > Good point, but I do think a nosymfollow is a good default. There's really no > reason to allow /tmp symlink race conditions to happen. SInce it's a memory > fs, disabling atime doesn't really make a big difference. > > Anyways just a suggestion, I'll be definitely setting nosymfollow on my > machine here. I'm a bit worried about giving a false sense of "secure default setup", by having /tmp mounted as "nosymfollow". Users who are determined to attempt symlink race hacks may also set TMPDIR=/var/tmp or even TMPDIR=/home/smartass/tmp and try their luck there. Mounting both /tmp and /var as nosymfollow runs the risk of crippling everyone's use of the file systems without actually being a 100% bulletproof solution. - Giorgos
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