Date: Thu, 7 Jul 2016 18:26:50 +0000 From: Grzegorz Junka <list1@gjunka.com> To: freebsd-jail@freebsd.org Subject: Re: Effective rule sets in a jail? Message-ID: <8d24b89f-3a83-ac6b-5051-c50accb24e9d@gjunka.com> In-Reply-To: <20160707153148.7da31609@eto-mona.office.smartweb.sk> References: <2aeb6798-11ee-27c0-610a-d745aa322f97@gjunka.com> <CANJ8om5R-BT=heC%2BgiMTXFH8YQXhuPQZjQ_S-P1bQ1XBGS16uQ@mail.gmail.com> <577E0A78.1040600@quip.cz> <2c9d10fd-35ba-5470-026d-a1483e47fcf2@gjunka.com> <577E1AFB.90100@quip.cz> <6ccead58-a38a-80a4-b5b8-a509c4271b8f@gjunka.com> <577E29A8.5000504@quip.cz> <4d3f5584-7dd1-e6fc-540f-9ed3f1fb63f4@gjunka.com> <20160707153148.7da31609@eto-mona.office.smartweb.sk>
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On 07/07/2016 13:31, Martin "eto" Misuth wrote: > IMHO, regarding jails, better mental model would be like this: > - any single jail can have one and only one devfs ruleset number assigned > - however, different standalone jails can have different devfs ruleset > number assigned > - nested jails inherit ruleset number from their parent jail > > Regarding rulesets "inheritance"/"merging" you are probably looking into the > wrong place. devfs ruleset system is completely orthogonal to jails, as it > is used for other things as well. > > You can "merge" devfs rulesets in devfs /etc/devfs.rules. > > Look into /etc/defaults/devfs.rules how initial rulesets are built. > > First everything is hidden by ruleset 1 aka "devfsrules_hide_all". This is "by > default deny" policy, which should, according to me, used whenever one can. > > Then, new rulesets are created by unhiding various groups of devices. > Like for example you have minimal sub-ruleset 2 aka "devfsrules_unhide_basic". > That one is required to get minimal working /dev. Otherwise most programs break. > > Finally ruleset 4 aka "devfsrules_jail" is built, which can be used by jails. > > I personally "classify" jail types into groups. Let's call such group a jail > "class" (for the purpose of classification). > > Thus to get what you want, you should create custom ruleset per jail "class" and > assign it to your jails based on their "class". > > [devfsrules_jail_class_no_zfs=16] > add include $devfsrules_hide_all > add include $devfsrules_unhide_basic > add include $devfsrules_unhide_login > > Class might be not good word for this, as it is quite "loaded" by now, but I am > using it that way. > > Some jails might end up so special, they require completely fine tuned ruleset. > Those cannot be completely "classified" at all like this for example: > > [devfsrules_jail_proxy=333] > add include $devfsrules_hide_all > add include $devfsrules_unhide_basic > add include $devfsrules_unhide_login > add include $devfsrules_unhide_jail_proxy_tuns > > "devfsrules_unhide_jail_proxy_tuns" sub-rule in this case unhides > several tun interfaces used solely by this jail only. > > devfs.conf files are "parsed" by /etc/rc.d/devfs rc script which is run quite > early after boot. If you look at it you will see it is using /etc/rc.subr > devfs_* subroutines of rc.d framework which invoke /sbin/devfs helper program. > > Theoretically if /etc/rc.d/devfs and /etc/rc.subr are not enough for > you, you could write helper script to invoke /sbin/devfs to setup most > convoluted rule ids directly by hand. > > eto > _______________________________________________ > freebsd-jail@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-jail > To unsubscribe, send any mail to "freebsd-jail-unsubscribe@freebsd.org" That's great! Thanks for the comprehensive explanation, I wish it was in the man already so I wouldn't need to enquiry additionally here. It makes sense, as I mentioned in my previous email, I got confused and messed jail inheritance with the inheritance of devfs rule sets, they are orthogonal as you stated. I amended my rules to include the basic ones from rule 4 to the more specific one for one particular jail and it works. Thanks again! Grzegorz
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