Messages in this thread | | | Date | Fri, 20 Apr 2012 02:28:30 +0400 | From | Konstantin Khlebnikov <> | Subject | Re: + c-r-prctl-add-ability-to-set-new-mm_struct-exe_file-update-after-mm- num_exe_file_vmas-removal.patch added to -mm tree |
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Oleg Nesterov wrote: > On 04/20, Cyrill Gorcunov wrote: >> >> Guys, while I more-less agree with Matt about single-shot behaviour >> >> [ let me copy my and his email >> >> >> With mm->exe_file this prctl option become a one-shot >> >> only, and while at moment our user-space tool can perfectly >> >> live with that I thought that there is no strict need to >> >> limit the option this way from the very beginning. >> >> >> > As far as backward compatibility, isn't it better to lift that restriction >> > later rather than add it? I think the latter would very likely "break" >> > things whereas the former would not. >> > >> > I also prefer that restriction because it establishes a bound on how >> > frequently the symlink can change. Keeping it a one-shot deal makes the >> > values that show up in tools like top more reliable for admins. >> ] >> >> I guess maybe it's time to drop one-shot requirement and as result >> we can drop MMF_EXE_FILE_CHANGED bit completely, > > Plus perhaps we can remove this for_each_vma check? > >> making overall code >> simplier? > > Personally I'd certainly prefer this ;) > > > > But let me repeat to avoid the confusion. I am fine either way, > I am not going to discuss this again unless I see something which > looks technically wrong. And the current MMF_EXE_FILE_CHANGED > doesn't look right even if the problem is minor.
Yeah, whole this protection does not protect anything and can be easily bypassed. For example task can re-execute itself and change exe-file again and again.
> > Oleg. >
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