Date: Sun, 18 Sep 2011 22:12:39 -0700 From: Kees Cook <kees@...ntu.com> To: David Windsor <dwindsor@...il.com> Cc: ubuntu-hardened@...ts.ubuntu.com, kernel-hardening@...ts.openwall.com Subject: Re: Sysctl for set_kernel_text_r[wo] Hi David, On Sun, Sep 18, 2011 at 09:42:59PM -0400, David Windsor wrote: > I am looking into adding a sysctl that enables toggling of > set_kernel_text_rw, set_kernel_text_ro. It appears that the only > caller of these methods is ftrace, which can rather easily be disabled > when these methods are unavailable. It would be really nice to be able to wipe these functions out. I really dislike that they are available as such perfect ROP targets. > I'm afraid I'm overlooking something major here. It seems that such a > control would have been added much earlier if it was actually as > simple as adding a guard variable, mutable via a sysctl, allowing > access to this interface. I haven't spent too much time looking into it, but I was under the impression that the module loader used some of the underlying functions too. Have you checked those code paths? -Kees -- Kees Cook
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