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Differential D87717

[docs] Update ControlFlowIntegrity.rst.
ClosedPublic

Authored by eugenis on Sep 15 2020, 12:51 PM.

Details

Reviewers
pcc
pirama
ivanlozano
Commits
rG66cf68ed4678: [docs] Update ControlFlowIntegrity.rst.
Summary

Expand the list of targets that support cfi-icall.
Add ThinLTO everywhere LTO is mentioned. AFAIK all CFI features are
supported with ThinLTO.

Diff Detail

Unit TestsFailed

TimeTest
780 mslinux > libomp.lock::omp_init_lock.c

Event Timeline

eugenis created this revision.Sep 15 2020, 12:51 PM
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eugenis added reviewers: pirama, ivanlozano.Sep 15 2020, 12:51 PM
Harbormaster completed remote builds in B71775: Diff 292005.Sep 15 2020, 1:25 PM
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pcc accepted this revision.Sep 25 2020, 5:42 PM

LGTM

This revision is now accepted and ready to land.Sep 25 2020, 5:42 PM
MaskRay added a subscriber: MaskRay.Sep 25 2020, 5:48 PM
MaskRay added inline comments.
clang/docs/ControlFlowIntegrity.rst
372

typo: -flto=thin

eugenis updated this revision to Diff 295888.Oct 2 2020, 12:00 PM

fix a typo

eugenis marked an inline comment as done.Oct 2 2020, 12:00 PM
This revision was landed with ongoing or failed builds.Oct 2 2020, 12:02 PM
Closed by commit rG66cf68ed4678: [docs] Update ControlFlowIntegrity.rst. (authored by eugenis). · Explain Why
This revision was automatically updated to reflect the committed changes.
eugenis added a commit: rG66cf68ed4678: [docs] Update ControlFlowIntegrity.rst..
Harbormaster completed remote builds in B73822: Diff 295888.Oct 2 2020, 12:17 PM

Revision Contents

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docs/
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Diff 295888

clang/docs/ControlFlowIntegrity.rst

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You can use ``-fsanitize=cfi`` to enable all the schemes and use You can use ``-fsanitize=cfi`` to enable all the schemes and use
``-fno-sanitize`` flag to narrow down the set of schemes as desired. ``-fno-sanitize`` flag to narrow down the set of schemes as desired.
For example, you can build your program with For example, you can build your program with
``-fsanitize=cfi -fno-sanitize=cfi-nvcall,cfi-icall`` ``-fsanitize=cfi -fno-sanitize=cfi-nvcall,cfi-icall``
to use all schemes except for non-virtual member function call and indirect call to use all schemes except for non-virtual member function call and indirect call
checking. checking.
Remember that you have to provide ``-flto`` if at least one CFI scheme is Remember that you have to provide ``-flto`` or ``-flto=thin`` if at
enabled. least one CFI scheme is enabled.
Trapping and Diagnostics Trapping and Diagnostics
======================== ========================
By default, CFI will abort the program immediately upon detecting a control By default, CFI will abort the program immediately upon detecting a control
flow integrity violation. You can use the :ref:`-fno-sanitize-trap= flow integrity violation. You can use the :ref:`-fno-sanitize-trap=
<controlling-code-generation>` flag to cause CFI to print a diagnostic <controlling-code-generation>` flag to cause CFI to print a diagnostic
similar to the one below before the program aborts. similar to the one below before the program aborts.
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unit not compiled with ``-fsanitize=cfi-icall``. This is technically a unit not compiled with ``-fsanitize=cfi-icall``. This is technically a
violation of the C and C++ standards, but it should not affect most programs. violation of the C and C++ standards, but it should not affect most programs.
Each translation unit compiled with ``-fsanitize=cfi-icall`` must be Each translation unit compiled with ``-fsanitize=cfi-icall`` must be
statically linked into the program or shared library, and calls across statically linked into the program or shared library, and calls across
shared library boundaries are handled as if the callee was not compiled with shared library boundaries are handled as if the callee was not compiled with
``-fsanitize=cfi-icall``. ``-fsanitize=cfi-icall``.
This scheme is currently only supported on the x86 and x86_64 architectures. This scheme is currently supported on a limited set of targets: x86,
x86_64, arm, arch64 and wasm.
``-fsanitize-cfi-icall-generalize-pointers`` ``-fsanitize-cfi-icall-generalize-pointers``
-------------------------------------------- --------------------------------------------
Mismatched pointer types are a common cause of cfi-icall check failures. Mismatched pointer types are a common cause of cfi-icall check failures.
Translation units compiled with the ``-fsanitize-cfi-icall-generalize-pointers`` Translation units compiled with the ``-fsanitize-cfi-icall-generalize-pointers``
flag relax pointer type checking for call sites in that translation unit, flag relax pointer type checking for call sites in that translation unit,
applied across all functions compiled with ``-fsanitize=cfi-icall``. applied across all functions compiled with ``-fsanitize=cfi-icall``.
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.. _cfi-cross-dso: .. _cfi-cross-dso:
Shared library support Shared library support
====================== ======================
Use **-f[no-]sanitize-cfi-cross-dso** to enable the cross-DSO control Use **-f[no-]sanitize-cfi-cross-dso** to enable the cross-DSO control
flow integrity mode, which allows all CFI schemes listed above to flow integrity mode, which allows all CFI schemes listed above to
apply across DSO boundaries. As in the regular CFI, each DSO must be apply across DSO boundaries. As in the regular CFI, each DSO must be
built with ``-flto``. built with ``-flto`` or ``-flto=thin``.
MaskRayUnsubmitted
Done
ReplyInline Actions

typo: -flto=thin

MaskRay: typo: `-flto=thin`
Normally, CFI checks will only be performed for classes that have hidden LTO Normally, CFI checks will only be performed for classes that have hidden LTO
visibility. With this flag enabled, the compiler will emit cross-DSO CFI visibility. With this flag enabled, the compiler will emit cross-DSO CFI
checks for all classes, except for those which appear in the CFI blacklist checks for all classes, except for those which appear in the CFI blacklist
or which use a ``no_sanitize`` attribute. or which use a ``no_sanitize`` attribute.
Design Design
====== ======
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