Messages in this thread | | | Date | Tue, 5 Oct 2021 13:36:55 -0700 | From | Josh Poimboeuf <> | Subject | Re: [PATCH v4 00/15] x86: Add support for Clang CFI |
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On Thu, Sep 30, 2021 at 11:05:16AM -0700, Sami Tolvanen wrote: > This series adds support for Clang's Control-Flow Integrity (CFI) > checking to x86_64. With CFI, the compiler injects a runtime > check before each indirect function call to ensure the target is > a valid function with the correct static type. This restricts > possible call targets and makes it more difficult for an attacker > to exploit bugs that allow the modification of stored function > pointers. For more details, see: > > https://clang.llvm.org/docs/ControlFlowIntegrity.html > > Note that v4 is based on tip/master. The first two patches contain > objtool support for CFI, the remaining patches change function > declarations to use opaque types, fix type mismatch issues that > confuse the compiler, and disable CFI where it can't be used. > > You can also pull this series from > > https://github.com/samitolvanen/linux.git x86-cfi-v4
Does this work for indirect calls made from alternatives?
I'm also wondering whether this works on CONFIG_RETPOLINE systems which disable retpolines at runtime, combined with Peter's patch to use objtool to replace retpoline thunk calls with indirect branches:
9bc0bb50727c ("objtool/x86: Rewrite retpoline thunk calls")
Since presumably objtool runs after the CFI stuff is inserted.
-- Josh
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