Date: Sun, 7 Aug 2011 12:37:49 +0200 From: "Simon L. B. Nielsen" <simon@nitro.dk> To: Jamie Gritton <jamie@FreeBSD.org> Cc: freebsd-jail@FreeBSD.org, Paul Schenkeveld <freebsd@psconsult.nl>, freebsd-arch@FreeBSD.org Subject: Re: New jail(8) with configuration files, not yet in head Message-ID: <005878F6-3CF5-482E-98E8-E5E4B8CA6C99@nitro.dk> In-Reply-To: <4E25BB7C.4090106@FreeBSD.org> References: <4E114EA9.4000605@FreeBSD.org> <20110718190839.GA81421@psconsult.nl> <4E25BB7C.4090106@FreeBSD.org>
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On 19 Jul 2011, at 19:14, Jamie Gritton wrote: > On 07/18/11 13:08, Paul Schenkeveld wrote: > >> Although I really like this new functionality, there is one issue that >> I am concerned about. Should all this functionality be integrated into >> the jail(8) command? > > This project came from a desire to improve the jail startup procedure in rc.d/jail, which remains stuck handling the old fixed-parameter jails. Rather that continue to extend an already unwieldy number of rc.conf shell variables, I opted to add a configuration file like other subsystems use (e.g. apmd, devd). The new jail pseudo-parameters added to the config file exist mostly to match the existing rc.d/jail functionality - the mount.* and exec.* parameters are direct analogs to rc.conf shell variables. Some other parameters match the command-line options of the existing jail(8). [This is less a mail to Jamie and more me getting around to publicly supporting they way it's done] A thing to note is also that when starting a jail you have to be really careful to do all of the related operations in the right order and in a safe manner. E.g. mounting file systems are only safe in some circumstances (ref: symlink attacks) so that's one reason I think the new approach is the right one. Also try reading the current rc.d/jail code for checking for those symlinks etc... not pretty. There are also some other quirks which means a slightly more comprehensive program is better. E.g. current rc.d jails have a bug where they can actually fill /tmp if they produce a lot of console output due to redirection to temp file (this is rarely a real problem so I never gotten around to trying to fix it). Bloat is of course a concern, but I don't think that risk outweigh the benefits of Jamie's new work. There is still room and need for a wrapper management framework (ezjail or something close to it) which handles the actual creation, update etc. which makes sense as a separate utility not part of jail(8). ezjail already uses rc.d/jail heavily so I think it can nicely integrate with the new jail(8). > I wouldn't want to do away with a config file, as that's a much cleaner way to define multiple jails than depending on the rc system or requiring a "roll your own" approach that is currently the only way to use the newer features. Just reading /etc/rc.d/jail is IMO good proof of this... > It's clear now that this won't be happening in 9.0. So none of this is in danger of getting pushed through in a hurry. I really hope that this can go into head shortly after the branch so it can hopefully make it into 9.1. -- Simon L. B. Nielsen
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