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RFC: Shadow Stack support in glibc
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: GNU C Library <libc-alpha at sourceware dot org>
- Cc: Igor Tsimbalist <tigor dot tools at gmail dot com>, vedvyas dot shanbhogue at intel dot com, yu-cheng dot yu at intel dot com
- Date: Mon, 5 Jun 2017 14:36:14 -0700
- Subject: RFC: Shadow Stack support in glibc
- Authentication-results: sourceware.org; auth=none
To support Shadow Stack in Intel Control-flow Enforcement Technology (CET)
Most of glibc functions are compatible with Shadow Stack, except for
1. setjmp/longjmp need to be extended to support Shadow Stack.
2. getcontext/setcontext may be extended to support Shadow Stack.
3. makecontext/swapcontext are hard to support Shadow Stack.
To enable Shadow Stack in glibc, there are 2 approaches:
1. Only support Shadow Stack in getcontext/setcontext and disallow
makecontext/swapcontext when Shadow Stack is used.
2. Disallow getcontext/setcontext/makecontext/swapcontext when
when Shadow Stack is used.
If we decide to disallow getcontext/setcontext/makecontext/swapcontext
when Shadow Stack is used, should we add a new set of functions
compatible with Shadow Stack to manipulate user context?