When used in cross-DSO mode, CFI will generate calls to special functions rather than trap instructions. For example, instead of generating
if (!InlinedFastCheck(f))
abort();
call *f
CFI generates
if (!InlinedFastCheck(f))
__cfi_slowpath(CallSiteTypeId, f);
call *f
This patch teaches cfi-verify to recognize calls to __cfi_slowpath and abort and treat them as trap functions.
In addition to normal symbols, we also parse the dynamic relocations to handle cross-DSO calls in libraries.
We also extend cfi-verify to recognize other patterns that occur using cross-DSO. For example, some indirect calls are not guarded by a branch to a trap but instead follow a call to __cfi_slowpath. For example:
if (!InlinedFastCheck(f))
call *f
else {
__cfi_slowpath(CallSiteTypeId, f);
call *f
}
In this case, the second call to f is not marked as protected by the current code. We thus recognize if indirect calls directly follow a call to a function that will trap on CFI violations and treat them as protected.
We also ignore indirect calls in the PLT, since on AArch64 each entry contains an indirect call that should not be protected by CFI, and these are labeled incorrectly when debug information is not present.
Differential Revision: https://reviews.llvm.org/D49383
llvm-svn: 340612
As suggested in the review for r337007, this makes cfi-verify abort on unsupported targets instead of producing incorrect results. It also updates the design document to reflect this.
Differential Revision: https://reviews.llvm.org/D49304
llvm-svn: 337181
This patch adds support for AArch64 to cfi-verify.
This required three changes to cfi-verify. First, it generalizes checking if an instruction is a trap by adding a new isTrap flag to TableGen (and defining it for x86 and AArch64). Second, the code that ensures that the operand register is not clobbered between the CFI check and the indirect call needs to allow a single dereference (in x86 this happens as part of the jump instruction). Third, we needed to ensure that return instructions are not counted as indirect branches. Technically, returns are indirect branches and can be covered by CFI, but LLVM's forward-edge CFI does not protect them, and x86 does not consider them, so we keep that behavior.
In addition, we had to improve AArch64's code to evaluate the branch target of a MCInst to handle calls where the destination is not the first operand (which it often is not).
Differential Revision: https://reviews.llvm.org/D48836
llvm-svn: 337007
Summary:
This update now allows users to specify `--blame-context` and `--blame-context-all` to print source file blame information for the source of the blame.
Also updates the inline printing to correctly identify the top of the inlining stack for blame information.
Patch by Mitch Phillips!
Reviewers: vlad.tsyrklevich
Subscribers: llvm-commits, kcc, pcc
Differential Revision: https://reviews.llvm.org/D40111
llvm-svn: 324035
We currently use target_link_libraries without an explicit scope
specifier (INTERFACE, PRIVATE or PUBLIC) when linking executables.
Dependencies added in this way apply to both the target and its
dependencies, i.e. they become part of the executable's link interface
and are transitive.
Transitive dependencies generally don't make sense for executables,
since you wouldn't normally be linking against an executable. This also
causes issues for generating install export files when using
LLVM_DISTRIBUTION_COMPONENTS. For example, clang has a lot of LLVM
library dependencies, which are currently added as interface
dependencies. If clang is in the distribution components but the LLVM
libraries it depends on aren't (which is a perfectly legitimate use case
if the LLVM libraries are being built static and there are therefore no
run-time dependencies on them), CMake will complain about the LLVM
libraries not being in export set when attempting to generate the
install export file for clang. This is reasonable behavior on CMake's
part, and the right thing is for LLVM's build system to explicitly use
PRIVATE dependencies for executables.
Unfortunately, CMake doesn't allow you to mix and match the keyword and
non-keyword target_link_libraries signatures for a single target; i.e.,
if a single call to target_link_libraries for a particular target uses
one of the INTERFACE, PRIVATE, or PUBLIC keywords, all other calls must
also be updated to use those keywords. This means we must do this change
in a single shot. I also fully expect to have missed some instances; I
tested by enabling all the projects in the monorepo (except dragonegg),
and configuring both with and without shared libraries, on both Darwin
and Linux, but I'm planning to rely on the buildbots for other
configurations (since it should be pretty easy to fix those).
Even after this change, we still have a lot of target_link_libraries
calls that don't specify a scope keyword, mostly for shared libraries.
I'm thinking about addressing those in a follow-up, but that's a
separate change IMO.
Differential Revision: https://reviews.llvm.org/D40823
llvm-svn: 319840
Summary:
This patch adds another failure mode for `validateCFIProtection(..)`, wherein any register that affects the indirect control flow instruction is clobbered to between the CFI-check and the instruction's execution.
Also includes a modification to make MCInstrDesc::hasDefOfPhysReg public.
Reviewers: vlad.tsyrklevich
Reviewed By: vlad.tsyrklevich
Subscribers: llvm-commits, pcc, kcc
Differential Revision: https://reviews.llvm.org/D39820
llvm-svn: 318238
Allows users to view GraphResult objects in a DOT directed-graph format. This feature can be turned on through the --print-graphs flag.
Also enabled pretty-printing of instructions in output. Together these features make analysis of unprotected CF instructions much easier by providing a visual control flow graph.
Reviewers: pcc
Subscribers: llvm-commits, kcc, vlad.tsyrklevich
Differential Revision: https://reviews.llvm.org/D39819
llvm-svn: 318211
Refactors the behaviour of building graphs out of FileAnalysis, allowing for analysis of the GraphResult by the callee without having to rebuild the graph. Means when we want to analyse the constructed graph (planned for later revisions), we don't do repeated work.
Also makes CFI verification in FileAnalysis now return an enum that allows us to differentiate why something failed, not just that it did/didn't fail.
Reviewers: vlad.tsyrklevich
Subscribers: kcc, pcc, llvm-commits
Differential Revision: https://reviews.llvm.org/D39764
llvm-svn: 317927
Adds the blacklist behaviour to llvm-cfi-verify. Now will calculate which lines caused expected failures in the blacklist and reports the number of affected indirect CF instructions for each blacklist entry.
Also moved DWARF checking after instruction analysis to improve performance significantly - unrolling the inlining stack is expensive.
Reviewers: vlad.tsyrklevich
Subscribers: aprantl, pcc, kcc, llvm-commits
Differential Revision: https://reviews.llvm.org/D39750
llvm-svn: 317743
Adds blacklist parsing behaviour for filtering results into four categories:
- Expected Protected: Things that are not in the blacklist and are protected.
- Unexpected Protected: Things that are in the blacklist and are protected.
- Expected Unprotected: Things that are in the blacklist and are unprotected.
- Unexpected Unprotected: Things that are not in the blacklist and are unprotected.
now can optionally be invoked with a second command line argument, which specifies the blacklist file that the binary was built with.
Current statistics for chromium:
Reviewers: vlad.tsyrklevich
Subscribers: mgorny, llvm-commits, pcc, kcc
Differential Revision: https://reviews.llvm.org/D39525
llvm-svn: 317364
Summary: Help differentiate code and data by parsing DWARF information. This will reduce false positive rates where data is placed in executable sections and is mistakenly parsed as code, resulting in an inflation in the number of indirect CF instructions (and hence an inflation of the number of unprotected).
Also prints the DWARF line data around the region of each indirect CF instruction.
Reviewers: pcc
Subscribers: probinson, llvm-commits, vlad.tsyrklevich, mgorny, aprantl, kcc
Differential Revision: https://reviews.llvm.org/D38654
llvm-svn: 317050
Add a CFI protection check that is implemented by building a graph and inspecting the output to deduce if the indirect CF instruction is CFI protected. Also added the output of this instruction to printIndirectInstructions().
Reviewers: vlad.tsyrklevich
Subscribers: llvm-commits, kcc, pcc, mgorny
Differential Revision: https://reviews.llvm.org/D38428
llvm-svn: 316610
Implement a localised graph builder for indirect control flow
instructions. Main interface is through GraphBuilder::buildFlowGraph,
which will build a flow graph around an indirect CF instruction. Various
modifications to FileVerifier are also made to const-expose some members
needed for machine code analysis done by the graph builder.
Reviewers: vlad.tsyrklevich
Reviewed By: vlad.tsyrklevich
Subscribers: llvm-commits, kcc, pcc
Differential Revision: https://reviews.llvm.org/D38427
llvm-svn: 316372
Summary:
llvm-cfi-verify (D38379) introduced a potential build failure when compiling with `-DLLVM_BUILD_LLVM_DYLIB=ON -DLLVM_LINK_LLVM_DYLIB=ON`. Specific versions of cmake seem to treat the `add_subdirectory()` rule differently. It seems as if old versions of cmake BFS these rules, adding them to the fringe for expansion later. Newer versions of cmake seem to immediately execute CMakeFiles that are present in this subdirectory.
If the subdirectory is expanded through the fringe, the globbing resultant from `llvm_add_implicit_projects()` from `cmake/modules/AddLLVM.cmake:1012` means that `tools/llvm-shlib/CMakeFile.txt` gets executed before `tools/llvm-cfi-verify/lib/CMakeFile.txt`. As the latter CMakeFile adds a new library, this expansion order means that the library files required the unit tests in `unittests/tools/llvm-cfi-verify/` are not present in the dynamic library. This causes unit tests to fail as the required functions can't be found.
This change now ensures that the libraries created by `llvm-cfi-verify` are statically linked into the unit tests. As `tools/llvm-cfi-verify/lib` no longer adds anything to `llvm-shlib`, there should be no concern about the order-of-compilation.
Reviewers: skatkov, pcc
Reviewed By: skatkov, pcc
Subscribers: llvm-commits, kcc, pcc, aheejin, vlad.tsyrklevich, mgorny
Differential Revision: https://reviews.llvm.org/D39020
llvm-svn: 316059
Summary: Move llvm-cfi-verify into a class in preparation for CFI analysis to come.
Reviewers: vlad.tsyrklevich
Reviewed By: vlad.tsyrklevich
Subscribers: mgorny, llvm-commits, pcc, kcc
Differential Revision: https://reviews.llvm.org/D38379
llvm-svn: 315504
This reverts commit r315363. It has a simple build failure, but more
importantly I want to confirm that unit tests run in check-all to make
sure that they don't silently break in the future.
llvm-svn: 315370
Summary: Move llvm-cfi-verify into a class in preparation for CFI analysis to come.
Reviewers: vlad.tsyrklevich
Reviewed By: vlad.tsyrklevich
Subscribers: mgorny, llvm-commits, pcc, kcc
Differential Revision: https://reviews.llvm.org/D38379
llvm-svn: 315363
Summary: Resubmission of D37937. Fixed i386 target building (conversion from std::size_t& to uint64_t& failed). Fixed documentation warning failure about docs/CFIVerify.rst not being in the tree.
Reviewers: vlad.tsyrklevich
Reviewed By: vlad.tsyrklevich
Patch by Mitch Phillips
Subscribers: sbc100, mgorny, pcc, llvm-commits, kcc
Differential Revision: https://reviews.llvm.org/D38089
llvm-svn: 313809
Summary: Resubmission of D37937. Fixed i386 target building (conversion from std::size_t& to uint64_t& failed). Fixed documentation warning failure about docs/CFIVerify.rst not being in the tree.
Reviewers: vlad.tsyrklevich
Reviewed By: vlad.tsyrklevich
Patch by Mitch Phillips
Subscribers: mgorny, pcc, llvm-commits, kcc
Differential Revision: https://reviews.llvm.org/D38089
llvm-svn: 313798
Summary: Introduces the llvm-cfi-verify tool to llvm. Includes the design document (docs/CFIVerify.rst). Current implementation of the tool is simply a disassembler that identifies and prints the indirect control flow instructions.
Reviewers: vlad.tsyrklevich
Reviewed By: vlad.tsyrklevich
Patch by Mitch Phillips
Subscribers: llvm-commits, kcc, pcc, mgorny
Differential Revision: https://reviews.llvm.org/D37937
llvm-svn: 313688
Nico Weber