2018-05-27 3:33 GMT+02:00 Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>: > On Sat, May 26, 2018 at 5:32 PM Kees Cook <keescook@xxxxxxxxxxxx> wrote: > >> I went through some old threads from 2012 when e268337dfe26 was >> introduced, and later when things got looked at during DirtyCOW. There >> was discussion about removing FOLL_FORCE (in order to block writes on >> a read-only memory region). > > Side note, we did that for /dev/mem, and things broke. > > Thus commit f511c0b17b08 "Yes, people use FOLL_FORCE ;)" > > Side note, that very sam ecommit f511c0b17b08 is also the explanation for > why the patch under discussion now seems broken. > > People really do use "write to /proc/self/mem" as a way to keep the > mappings read-only, but have a way to change them when required. Oh, I didn't expect this, interesting... A configurable LSM is probably the right way to do this. Thank you for your time, Salvatore
