Messages in this thread | | | Date | Tue, 25 Sep 2007 17:39:19 +0200 | From | Miloslav Semler <> | Subject | Re: Chroot bug |
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> On Sep 26 2007 00:40, David Newall wrote: > >> Miloslav Semler pointed out that a root process can chdir("..") out of its >> chroot. Although this is documented in the man page, it conflicts with the >> essential function, which is to change the root directory of the process. In >> addition to any creative uses, for example Philipp Marek's loading dynamic >> libraries, it seems clear that the prime purpose of chroot is to aid security. >> Being able to cd your way out is handy for the bad guys, but the good guys >> don't need it; there are a thousand better, safer solutions. >> > > So what? Just do this: chdir into the root after chroot. > > It won't conform to SVR4/4.4BSD anymore, but hey, let Linux set some > sane standard ain't bad either. I doubt anyone really relies on the > fact that after chroot, your cwd might be outside the root. > so then you corrupt pwd. I think that working directory should be set only if it is necessary. Fn directory_is_out is not big performace loss. And also you can break this fix with fchdir.
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