Date: Sun, 10 Nov 2019 11:47:53 -0800 From: Conrad Meyer <cem@freebsd.org> To: svn-src-head@freebsd.org Cc: src-committers@freebsd.org, svn-src-all@freebsd.org Subject: Re: svn commit: r354458 - head/libexec/rc/rc.d Message-ID: <CAG6CVpWmttTuVCMyvczFxGY3qv5mYiC2FcvhifdROELYq3cjJw@mail.gmail.com> In-Reply-To: <20191110160819.GA1095@brick> References: <201911071815.xA7IFOhI070066@repo.freebsd.org> <20191109204958.Horde.B0ynnS_aur1OZimnDNObsAt@webmail.leidinger.net> <20191110160819.GA1095@brick>
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Hi, Response inline below. On Sun, Nov 10, 2019 at 08:08 Edward Tomasz Napierala <trasz@freebsd.org> wrote: > On 1109T2049, Alexander Leidinger wrote: > > Quoting Edward Tomasz Napierala <trasz@freebsd.org> (from Thu, 7 Nov > > 2019 18:15:24 +0000 (UTC)): > > > > > Author: trasz > > > Date: Thu Nov 7 18:15:24 2019 > > > New Revision: 354458 > > > URL: https://svnweb.freebsd.org/changeset/base/354458 > > > > > > Log: > > > Extend the linux rc script to mount the neccessary file systems, > > > set ELF fallback brand, and load pty(4). > > > > We never did something like that. We have it documented everywhere > > that it needs to be done manually. So this is at least a POLA > > violation. It is great that the nocover option is used in the mount, > > but it's still some kind of layering violation (I may want to have > > only a subset mounted, or nothing at all). > > It is kind of a POLA violation, but previously the linux_enable > knob didn't do much apart from loading the linux{,64}.ko kernel > module and doing something weird with ldconfig, which I'm not > even sure is actually useful. In other words, the old behaviour > can be restored by just not using linux_enable, and instead > loading the kernel modules the same way all the others are loaded. > > Could you give me some use case why someone would want only a subset > of the filesystems? They=E2=80=99re an additional attack surface. If your few linux applicatio= ns get by with fewer vfs, you might want to avoid the others. I=E2=80=99m not part= icularly attached to this reason. And imo, linux64.ko kind of dwarf that attack surface concern, so it=E2=80=99s maybe a silly point. Another problem with the current code is (and I may be mistaken here) I think that it ignores mount options configured in the admin=E2=80=99s /etc/= fstab. Eg I configure my /tmp with a hard limit on memory use and if I were to mount a compat shm tmpfs, I=E2=80=99d also want its memory use bounded. =E2= =80=9CNocover=E2=80=9D protects from covering any existing =E2=80=9Cauto=E2=80=9C mounts, but one = can imagine specifying the linux compat mount =E2=80=9Cnoauto=E2=80=9D. I am on board with making this stuff more =E2=80=9Cbatteries included=E2=80= =9D and usable by default, but just echoing the request for configurable knobs (I don=E2= =80=99t care about the defaults). Best, Conrad > > > > I do not object to the functionality, but I think it needs to be > > configurable (an option to influence if the auto-mount is done or not, > > doesn't matter to me what the default behavior is, as long as it is > > configurable) and documented (UPDATING, handbook, man-pages, maybe > > even the release notes). > > Man page updates are pending review at https://reviews.freebsd.org/D22277= . > Good point about the Handbook and release notes; I'll take a look. > >
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