obfuscated names in header files included from assembly fail at link time

[zcrypt0]

What version of Garble and Go are you using?

$ garble version v0.7.0

$ go version v1.18.3

What environment are you running Garble on?

go env Output

$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/user/.cache/go-build"
GOENV="/home/user/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.18.3"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/go-ethereum/go.mod"
GOWORK=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build3469986570=/tmp/go-build -gno-record-gcc-switches"

What did you do?

$ git clone https://github.com/ethereum/go-ethereum
$ cd go-ethereum
$ garble build -trimpath -v -o ./build/bin/geth ./cmd/geth

What did you expect to see?

Successfully compiling go-ethereum.

What did you see instead?

Lots of undefined references during linking, similar to the below.

/usr/local/go/pkg/tool/linux_amd64/link: running gcc failed: exit status 1

...

/usr/lib/gcc/x86_64-alpine-linux-musl/11.2.1/../../../../x86_64-alpine-linux-musl/bin/ld: go.go:(.text+0x539c15): undefined reference to `qlz7tY23.p2'
/usr/lib/gcc/x86_64-alpine-linux-musl/11.2.1/../../../../x86_64-alpine-linux-musl/bin/ld: go.go:(.text+0x539c2b): undefined reference to `qlz7tY23.p2'
/usr/lib/gcc/x86_64-alpine-linux-musl/11.2.1/../../../../x86_64-alpine-linux-musl/bin/ld: go.go:(.text+0x539c41): undefined reference to `qlz7tY23.p2'
/usr/lib/gcc/x86_64-alpine-linux-musl/11.2.1/../../../../x86_64-alpine-linux-musl/bin/ld: go.go:(.text+0x539c73): undefined reference to `qlz7tY23.p2'
/usr/lib/gcc/x86_64-alpine-linux-musl/11.2.1/../../../../x86_64-alpine-linux-musl/bin/ld: /tmp/go-link-1607869154/go.o:go.go:(.text+0x539c85): more undefined references to `qlz7tY23.p2' 

Comments

I dug in a little bit and with a whitelist, select packages can be obfuscated just fine.

Running with -debug I can see the package with undefined references:

[garble] import path "github.com/ethereum/go-ethereum/crypto/bn256/cloudflare" hashed with 5afaf34cfd103d0ff82a7f16d49c61 to "qlz7tY23"

Seeing the same result on tip of master.

EDIT:
I blacklisted that particular module from being obfuscated, and the rest of go-ethereum obfuscated just fine.

EDIT2:
Reversing also fails on the rpc subpackage (github.com/ethereum/go-ethereum), no actual panic output is required.

$ garble reverse ./cmd/geth ./out/panic-output.txt
typecheck error: /go-ethereum/rpc/ipc_unix.go:34:25: undeclared name: max_path_size

Additionally blacklisting this package and reverse works as expected.

[mvdan]

Thank you - it seems like what's happening here is that names like p2 are not only used in assembly files, but also in header files, and we're currently not fixing those up.

[zcrypt0]

@mvdan Note my second edit, which should probably be a separate issue.

The var max_path_size is a package level var declared in another file and reverse (not build) seems to have some issue with it. Looks like it makes a call out to C for its value.

https://github.com/ethereum/go-ethereum/blob/master/rpc/ipc_unix.go#L34
https://github.com/ethereum/go-ethereum/blob/master/rpc/constants_unix.go#L33

[mvdan]

Thanks - could you please file that as a separate issue with repro steps? I'm fairly sure the two bugs are unrelated, and the assembly one is already a pretty involved fix.