Date: Sun, 26 Sep 1999 17:01:35 -0700 (PDT) From: Julian Elischer <julian@whistle.com> To: Carol Deihl <carol@tinker.com> Cc: freebsd-security@FreeBSD.ORG, freebsd-hackers@FreeBSD.ORG Subject: Re: chroot could chdir? (was Re: about jail) Message-ID: <Pine.BSF.4.05.9909261700010.27653-100000@home.elischer.org> In-Reply-To: <37EEA27E.244DCF9A@tinker.com>
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You have to examine ALL fd's in case one has a directory open that is outside the chroot.. (see man fchdir(2)) julian On Sun, 26 Sep 1999, Carol Deihl wrote: > Alexander Bezroutchko wrote: > > it is possible to escape from jail > > Following program escapes from jail (tested under 4.0-19990918-CURRENT): > [snip program code that chroot's but doesn't then chdir inside > the new area] > > As we all know, the chroot can be escaped because the sample > program doesn't change the current working directory, and it's > still pointing outside the chrooted area. > > What if chroot itself chdir'ed to it's new root directory? Would > this break existing programs? I'd expect that well-behaved > programs would chdir someplace useful before continuing anyway. > > At the very end of chroot(), could it just > vrele(fdp->fd_cdir); > fdp->fd_cdir = nd.ni_vp; > before it returns, setting the current dir to the same place it > just chrooted to? > > Carol > -- > Carol Deihl - principal, Shrier and Deihl - mailto:carol@tinker.com > Remote Unix Network Admin, Security, Internet Software Development > Tinker Internet Services - Superior FreeBSD-based Web Hosting > http://www.tinker.com/ > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-hackers" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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