Date: Thu, 12 Apr 2001 11:14:40 -0700 From: Alfred Perlstein <bright@wintelcom.net> To: Thomas Quinot <quinot@inf.enst.fr> Cc: current@FreeBSD.ORG Subject: Re: NFS export to netgroup with duplicate hosts Message-ID: <20010412111440.F24582@fw.wintelcom.net> In-Reply-To: <20010412200617.A12763@shalmaneser.enst.fr>; from quinot@inf.enst.fr on Thu, Apr 12, 2001 at 08:06:17PM %2B0200 References: <20010412182900.B30764@cuivre.fr.eu.org> <Pine.SGI.4.10.10104121836360.3093471-100000@harem.imp.ch> <20010412110021.D24582@fw.wintelcom.net> <20010412200617.A12763@shalmaneser.enst.fr>
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* Thomas Quinot <quinot@inf.enst.fr> [010412 11:06] wrote: > Le 2001-04-12, Alfred Perlstein écrivait : > > > m: "Don't call me dude." *thwack* "The point is that if the > > workstation is untrusted, what's the stop the mallicious hacker > > from taking a read-only filehandle and swapping the top byte with > > the byte required for write access?" > > The kernel could include a 'signature' in the handle, e.g. in the form of > a hash of (perm-bytes,handle-bytes,secret-key). > > (But the following still holds:) > > > s: "Master, this sounds like hella work!" > (plus some crypto algorithm right in kernel space...) > > > m: "Ahhhh, you are correct, now get cracking!" None of that would protect you when a single client has two exports available, one read and one write on the same filesystem. A machine with just / that exports /usr and /var with different perms... (/usr is rw, /var is ro) Well the untrusted client can use the "magic" from the /usr to access /var rw instead of ro. It's actually not that big of a deal to attach the client/perms though so that seperate machines can access the same mount point differently. -- -Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org] http://www.egr.unlv.edu/~slumos/on-netbsd.html To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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