Messages in this thread | | | Subject | Re: stop breaking dosemu (Re: x86/kconfig/32: Rename CONFIG_VM86 and default it to 'n') | From | Stas Sergeev <> | Date | Thu, 3 Sep 2015 15:09:35 +0300 |
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03.09.2015 15:01, Austin S Hemmelgarn пишет: > On 2015-09-02 17:12, Stas Sergeev wrote: >> 02.09.2015 23:55, Andy Lutomirski пишет: >>> On Wed, Sep 2, 2015 at 1:47 PM, Stas Sergeev <stsp@list.ru> wrote: >>>> 02.09.2015 23:22, Josh Boyer пишет: >>>>> On Wed, Sep 2, 2015 at 1:50 PM, Stas Sergeev <stsp@list.ru> wrote: >>>>>> 02.09.2015 20:46, Josh Boyer пишет: >>>>>>> On Wed, Sep 2, 2015 at 10:08 AM, Andy Lutomirski >>>>>>> <luto@amacapital.net> >>>>>>> wrote: >>>>>>>> I'd be amenable to switching the default back to y and perhaps >>>>>>>> adding >>>>>>>> a sysctl to make the distros more comfortable. Ingo, Kees, Brian, >>>>>>>> what do you think? >>>>>>> Can you please leave the default as N, and have a sysctl option to >>>>>>> enable it instead? While dosemu might still be in use, it isn't >>>>>>> going >>>>>>> to be the common case at all. So from a distro perspective, I think >>>>>>> we'd probably rather have the default match the common case. >>>>>> The fact that fedora doesn't package dosemu, doesn't automatically >>>>>> mean all other distros do not too. Since when kernel defaults should >>>>>> match the ones of fedora? >>>>> I didn't say that. >>>> What you said was: >>>> --- >>>> >>>> While dosemu might still be in use, it isn't going >>>> to be the common case at all. So from a distro perspective >>>> >>>> --- >>>> ... which is likely true only in fedora circe. >>>> >>>>> The default right now is N. >>>> In a not yet released kernel, unless I am mistaken. >>>> If fedora already provides that kernel, other distros likely not. >>>> >>>>> I asked it be left >>>>> that way. That's all. >>>> Lets assume its not yet N, unless there was a kernel release already. >>>> Its easy to get back if its not too late. >>> How about CONFIG_SYSCTL_VM86_DEFAULT which defaults to Y? Fedora >>> could set it to N. >> Sorry, I don't understand this sysctl proposal. >> Could you please educate me what is it all about? >> This sysctl will disable or enable the vm86() syscall at run-time, >> right? What does it give us? If you disable something in the >> config, this gives you, say, smaller kernel image. If OTOH you >> add the run-time switch, it gives you a bigger image, regardless >> of its default value. >> I might be missing something, but I don't understand what >> problem will this solve? Have I missed some earlier message >> in this thread? > The problem this solves is not kernel size, that is not the only reason for wanting to disable a system call. In this case, it's a system call that is unused by all but a very few programs, which are > in turn used by a small percentage of users, and said system call does quite a few things that are potentially very dangerous. Disabling it reduces the attack surface of the system. Well, thanks for explaining the marketing part of the problem (initially I wasn't aware, but now Andy already spelled it too), but the reality is different.
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