Date: Tue, 13 Mar 2018 17:16:48 -0600 From: Warner Losh <imp@bsdimp.com> To: Mark Saad <nonesuch@longcount.org> Cc: "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org>, Kristoffer Eriksson <ske@pkmab.se>, Theron <theron.tarigo@gmail.com> Subject: Re: GSoC Idea: per-process filesystem namespaces for FreeBSD Message-ID: <CANCZdfq3J75k2GRvWa7k-n29VST6x00Pz1NUQAmwSMtfCSEOEQ@mail.gmail.com> In-Reply-To: <BACCA158-AB12-4DE1-B70A-2084FF2C5806@longcount.org> References: <d7621074-acb4-c5b6-1efd-dc55b51586b1@gmail.com> <201803132055.aa28780@berenice.pkmab.se> <CANCZdfoU1B4228RpwfupvdVN9RPCCug4p283xmkNwW7t-M9CjA@mail.gmail.com> <BACCA158-AB12-4DE1-B70A-2084FF2C5806@longcount.org>
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On Tue, Mar 13, 2018 at 4:31 PM, Mark Saad <nonesuch@longcount.org> wrote: > > On Mar 13, 2018, at 5:43 PM, Warner Losh <imp@bsdimp.com> wrote: > > On Tue, Mar 13, 2018 at 1:55 PM, Kristoffer Eriksson <ske@pkmab.se> wrote= : > > > On 13 Mar 2018 12:53:18, Theron <theron.tarigo@gmail.com> wrote: > > For those unfamiliar with Plan9, here is a rough explanation of the > > namespace feature: unlike in Unix, where all processes share the same > > virtual filesystem, each process instead has its own view of the > > filesystem according to what has been mounted ... > > > What if I mount a new /etc with a passwd file where root has no > > password, and then run "su"? > > > (How does Plan9 handle that?) > > > > Plan9 handles that by having a daemon that does user authentication. It's > actually more complicated than that, but the machine owner has control ov= er > who can do what. For this to work in FreeBSD, either we'd need to disallo= w > the 'file' type for passwd, or we'd have to do something sensible with > setuid programs. Well, maybe not 'or' but 'and' since the security of > setuid programs depends on the security of the filesystem.... Plan 9 > doesn't have these complications, so it can offer a user malleable > filesystem without security risk. > > Warner > > > A kind of related task; FreeBSD could benefit from : Fixing and > improving unionfs / nullfs. There are some weird issues with the current > unionfs and while it works in many cases there are some edge cases where > the comments are something like =E2=80=9C FreeBSD needs a proper stacking= vfs ...=E2=80=9D > the examples I can think of ; imagine you have a jail , chroot or even = a > Pxe booted system where you want a a read only null mount from the hosts > /bin to the targets /bin . Now expand that to most of the base system and > the mount tmpfs=E2=80=99s for /tep /var/log etc. most of that works but = try to > unmount it in the wrong order or thrash a unionfs with lots of writes ,on > top of a tmpfs and things break . > So to be clear the project would be to better document the various uses o= f > unionfs and nullfs that work , for the ones that do not diving into the > stacking vfs and seeing if it could be implemented and if it would help . > > Alternatively making FreeBSD multiboot compliant would rock . This would > allow FreeBSD to natively boot from ipxe or syslinux derivates; thus > allowing you to boot a working FreeBSD install via a kernel and mfsroot > image off a web server . > There appears to already be a multiboot.c in the bootloader. I've been told by others in the past it just works... Warner
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