On Wed, Jan 24, 2024 at 9:47 PM Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > > On Wed, 24 Jan 2024 at 12:15, Kees Cook <keescook@xxxxxxxxxxxx> wrote: > > > > Hmpf, and frustratingly Ubuntu (and Debian) still builds with > > CONFIG_USELIB, even though it was reported[2] to them almost 4 years ago. > > Well, we could just remove the __FMODE_EXEC from uselib. > > It's kind of wrong anyway. > > Unlike a real execve(), where the target executable actually takes > control and you can't actually control it (except with ptrace, of > course), 'uselib()' really is just a wrapper around a special mmap. > > And you can see it in the "acc_mode" flags: uselib already requires > MAY_READ for that reason. So you cannot uselib() a non-readable file, > unlike execve(). > > So I think just removing __FMODE_EXEC would just do the > RightThing(tm), and changes nothing for any sane situation. Sounds like a good idea. That makes this codepath behave more as if userspace had done the same steps manually...
