GODEBUG started being used for configuring the behavior of the Go
toolchain and standard library, for the sake of smoother transitions
in terms of backwards and forwards compatibility.
See: https://go.dev/doc/godebug
As such, it is not right to have `garble build -tiny` ignore all
GODEBUG settings, because many GODEBUG keys nowadays do not actually
involve debugging what a Go binary is doing.
Moreover, the mechanism we were using broke with Go 1.25.2,
which refactored `func parsedebugvars()` into
`func parseRuntimeDebugVars(godebug string)`,
so our test started breaking as our runtime patching was broken.
Otherwise we might do odd things, such as trying to open the linker
patches directory "patches/" given that go/version.Lang
returns an empty string for invalid versions.
See #978.
We don't need to use a regular expression to find "goN.M" anymore,
as go/version seems to deal with "devel" versions from master just fine.
We can then also stop having two separate fields for the version
of the Go toolchain currently being used.
As spotted by scripts/check-third-party.sh, it's possible to import
the testing package without using `go test`, so our previous solution
to only load testing/synctest when running `go test` was not enough.
Add a regression test via stdimporter in gogarble.txtar.
While strictly speaking it would be okay to leave Go 1.24 support
in place for the time being, we are behind on a few tasks at the moment
so it's best to keep the setup at master simpler for the next release.
Go 1.25 already came out two weeks ago, and it seems to have been
a fairly smooth release, so I don't suspect any end users will have
trouble upgrading to it.
Note that two changes were necessary for garble to work on Go 1.25.0.
First, we stop deduplicating runtimeAndLinknamed with runtimeAndDeps.
Otherwise, for GOOS=windows, internal/runtime/cgroup would be missing
as it is a //go:linkname target from runtime on all platforms,
but it is not transitively imported from runtime on GOOS=windows.
Second, the testing/synctest package is now part of std,
and it is a //go:linkname target from the testing package
but not a transitive import from it. Teach appendListedPackages that,
when loading all packages for a `go test` run, it should load
the new testing/synctest package too.
Fixes#968.
Due to unsafe not being a real dependency, type checking during control-flow obfuscation was performed incorrectly.
This is fixed by excluding unsafe from the dependency checks.
Fixes#903
Some programs which could automatically reverse string literals obfuscated with `-literals` exist.
They currently work by emulating the string literal decryption functions we insert.
We prevent this naive emulation from succeeding by making the decryption functions dependent on global state.
This can still be broken with enough effort, we are curious which approach reverse-engineers come up with next, we certainly still have some ideas to make this harder.
Fixes#926
---------
Co-authored-by: Paul Scheduikat <lu4p@pm.me>
Some Go version managers like github.com/voidint/g use GOROOT symlinks,
which silently broke the way we patch the linker via go build -overlay.
Reproduced the original crash via the following testscript:
env GARBLE_CACHE=${WORK}/garble-cache
symlink goroot -> /usr/lib/go
env GOROOT=${WORK}/goroot
exec garble run main.go
-- main.go --
package main
import "fmt"
func main() {
fmt.Println("hello world")
}
We don't commit this testscript given how it's an expensive test
and for a relatively rare edge case whose fix is now well documented.
Moreover, as GOTOOLCHAIN is now available, I expect version managers
for Go to fade away with time.
While here, remove a debugging 'exec cat' from a testscript.
Fixes#915.
Or any other package which uses a //go:linkname to the runtime names
"lastmoduledatap" or "moduledataverify1". These are used by sonic
to inject function headers to the runtime, which does not work
as garble patches the runtime as part of obfuscation.
The way it alters the magic number in function headers breaks this.
Add a summary of this as a comment too.
Fixes#898.
When obfuscating a main package whose Go files all import "C",
the first Go file in CompiledGoFiles ends up being _cgo_gotypes.go.
We cannot add our code from reflect_abi_code.go there,
as it leads to the following error about its _trieNode type:
typecheck error: $WORK/b001/_cgo_gotypes.go:185:10: cannot define new methods on non-local type _trieNode
Avoid patching any _cgo_*.go file with our reflect code,
as all of those files are special glue code for cgo.
While here, tweak reflectMainPrePatch to return a string
for consistency with abiNamePatch.
Fixes#916.
Seems to happen when the main package only has Go files importing "C",
meaning that it has zero "pure Go" files.
To avoid needing two main package Go builds for cgo.txtar,
switch our main package to this scenario as it seems more interesting.
While here, add a test case for a Go callback function taking a C param
as that is relatively common and we had no coverage for it.
This only reproduces the bug; the fix is coming separately.
For #916.
Before Go 1.24, `go build` only stamped module versions for modules
resolved via GOPROXY, as the local module only had VCS information.
For that reason, we manually built a pseudo-version from the VCS
timestamp and revision stamped for local builds.
Go 1.24 started stamping the main module with a module version
derived from the local VCS information, much like we already did.
For example, comparing a clean build before this change
against a build with this uncommitted change:
$ go install
$ garble version
mvdan.cc/garble v0.14.3-0.20250413182748-e97968ccae46
[...]
$ git stash pop
$ go install
$ garble version
mvdan.cc/garble v0.14.3-0.20250413182748-e97968ccae46+dirty
[...]
The only user-visible change is that local builds with any
uncommitted changes now get a `+dirty` suffix, but that's probably
a good thing for the majority of users, and provides a useful hint
in case a user forgot about local changes.
The test logic to inject VCS information via an env var
and see that the resulting pseudo-version is what we expect can go too,
as that was testing our own main module version logic.
We now rely on `go build` to do the right thing, so don't test that.
When creating a new debugdir directory, add a sentinel .garble-debugdir
file at its root so that we can later know that we created it
and the user is very unlikely to have left important data there.
When emptying an existing debugdir directory, only do so if it has
that sentinel file, for added safety.
Fixes#932.
On CI we test on go1.23.x and go1.24.x, so if we always upgrade
to the latest go1.24.x, that will cause garble to complain
when running on go1.23.x:
garble was built with "go1.23.7" and can't be used with the newer "go1.24.1"
Moreover, the test hard-coded go1.24.1, which is currently the latest
go1.24.x but will not be for long, so this test was brittle.
We call `go list` to collect information about all the packages
to obfuscate and build, which is crucial to be able to perform
obfuscation of names used across packages.
However, when GOTOOLCHAIN causes a toolchain upgrade,
we must ensure that we use the upgraded Go tool;
otherwise we are mixing information from different toolchain versions.
Fixes#934.
When we build the patched cmd/link binary for use by garble,
we perform this build in a temporary directory so that the Go module
from the user does not get in the way.
When the user module made us upgrade the toolchain per GOTOOLCHAIN,
leaving that module's directory stops upgrading the toolchain,
so we patch a newer toolchain and build it with an older toolchain.
This is largely harmless, but it makes the newer toolchain think
it is actually an older toolchain, which leads to those pesky
"linker object header mismatch" version errors.
Updates #934.
debugdir.txtar also needed tweaking as runtime/map.go is gone
starting in Go 1.24.
Finally, modinfo.txtar needed tweaking since Go 1.24 started stamping
Go binaries with VCS-derived module versions, so we no longer end up
with empty "(devel)" versions.
We only did this for Container in the type switch, but not for Struct.
The added test case panics otherwise.
Just like in the previous case, we still don't need to recurse
into type parameters for fieldToStruct to be filled correctly.
Fixes#899
As spotted by the protobuf package via check-third-party.sh,
the two structs below are identical:
type alias1 = int64
type Struct1 struct { Alias alias1 }
type alias2 = int64
type Struct2 struct { Alias alias2 }
Our previous approach with stripStructTags dealt with struct tags,
but it did not deal with aliases, which are now present in go/types
thanks to the new alias tracking.
The new approach properly ignores struct tags and unaliases any
type aliases, resulting in correct hashes of any type.
Allows us to remove EmbeddedAliasFields, recordedObjectString,
and all the logic around using them.
Resolves an issue where a user was running into a panic in
our logic to record embedded aliases.
Note that this means we require Go 1.23.5 or later now,
which also meant some changes to goversion.txtar to keep it green.
Fixes#827.
Go code can retrieve and use field and method names via the `reflect` package.
For that reason, historically we did not obfuscate names of fields and methods
underneath types that we detected as used for reflection, via e.g. `reflect.TypeOf`.
However, that caused a number of issues. Since we obfuscate and build one package
at a time, we could only detect when types were used for reflection in their own package
or in upstream packages. Use of reflection in downstream packages would be detected
too late, causing one package to obfuscate the names and the other not to, leading to a build failure.
A different approach is implemented here. All names are obfuscated now, but we collect
those types used for reflection, and at the end of a build in `package main`,
we inject a function into the runtime's `internal/abi` package to reverse the obfuscation
for those names which can be used for reflection.
This does mean that the obfuscation for these names is very weak, as the binary
contains a one-to-one mapping to their original names, but they cannot be obfuscated
without breaking too many Go packages out in the wild. There is also some amount
of overhead in `internal/abi` due to this, but we aim to make the overhead insignificant.
Fixes#884, #799, #817, #881, #858, #843, #842Closes#406
This lets us start taking advantage of featurs from Go 1.23,
particularly tracking aliases in go/types and iterators.
Note that we need to add code to properly handle or skip over the new
*types.Alias type which go/types produces for Go type aliases.
Also note that we actually turn this mode off entirely for now,
due to the bug reported at https://go.dev/issue/70394.
We don't yet remove our own alias tracking code yet due to the above.
We hope to be able to remove it very soon.
Otherwise we miscalculate int sizes, type sizes, alignments, and so on.
Caught by the GOARCH=386 go test on CI, since the os package imports
internal/syscall/unix, which uses arch-dependent padding.
The different padding between our incorrect use of go/types
and the correct typechecking done by the compiler caused different
obfuscation of fields, as the struct types stringified differently,
and they are used as a hash salt for field name obfuscation.
Right now, we only have linker patches for Go 1.22.x.
We only ever maintain those for one or two major Go versions at a time.
If a user tries to use the Go toolchain from 1.21, we already fail
with "Go version too old" messages early on, but we don't for 1.23,
causing a relatively confusing error later on when we link a binary:
cannot get modified linker: cannot retrieve linker patches: open patches/go1.23: file does not exist
Instead, fail early and with a good error message.
When updating Garble to support Go 1.22.0, CI on MacOS spotted
that the syscall package was failing to build given that it uses
assembly code which is only allowed in some std packages.
That allowlist is based on import paths, and we were obfuscating
the syscall package's import path, so that was breaking GOOS=darwin.
As a fix, I added syscall to runtimeAndDeps to not obfuscate it.
That wasn't a great fix; it's not part of runtime and its dependencies,
and there's no reason we should avoid obfuscating the package contents.
Not obfuscating the contents in fact broke x/sys/unix,
as it contains a copy of syscall.Rlimit which it type converted with.
Undo that fix and reinstate the gogarble.txtar syscall test.
Implement the fix where we only leave syscall's import path alone.
Add a regression test, and add a note about adding x/net and x/sys
to check-third-party.sh so that we can catch these bugs earlier.
Fixes#830.
It seems like building with Go 1.22.0 for GOOS=darwin started
running into some issues with the syscall package's use of ABIInternal
in assembly source code:
> exec garble build
[stderr]
# syscall
[...].s:16: ABI selector only permitted when compiling runtime, reference was to "runtime.entersyscall"
The error can be reproduced from another platform like GOOS=linux
as long as we have any test that cross-compiles std to GOOS=darwin.
We had crossbuild.txtar which only ensured we covered GOOS=windows
and GOOS=linux, so add a third case to ensure MacOS is covered too.
This will slow down the tests a bit, but is important for the sake
of ensuring that we catch these bugs early, even without MacOS on CI.
In fact, we hadn't caught this earlier for Go 1.22 precisely because
on CI we only tested on Go tip with GOOS=linux, for the sake of speed.
Adding the rest of the package import paths from objabi.allowAsmABIPkgs
to our runtimeAndDeps generated map solves this error.
add trash block generator
For making static code analysis even more difficult, added feature for
generating trash blocks that will never be executed. In combination
with control flow flattening makes it hard to separate trash code from
the real one, plus it causes a large number of trash references to
different methods.
Trash blocks contain 2 types of statements:
1. Function/method call with writing the results into local variables
and passing them to other calls
2. Shuffling or assigning random values to local variables
That is, the assembly line
#include "foo.h" // bar
would make garble run into an error, as we would try to parse
the #include directive before we stripped comments,
effectively trying to unquote the string
"foo.h" // bar
rather than just the included filename
"foo.h"
Add test cases for asm but also cgo, while at it.
Fixes#812.
In some cases, compiler could optimize the shuffle obfuscator,
causing exposing the obfuscated literal.
As a fix, added xor encryption of array indexes.
TypeName.Pkg is documented as:
Pkg returns the package to which the object belongs.
The result is nil for labels and objects in the Universe scope.
When a struct type embeds a builtin alias type, such as byte,
this would lead to a panic since we assumed we could use the Pkg method.
Fixes#798.
This was a long standing TODO, and a user finally ran into it.
The fix isn't terribly straightforward, but I'm pretty happy with it.
Add a test case where the same struct field is identical
with no tag, with the "tagged1" json tag, and again with "tagged2".
While here, we add a test case for a regular named field too.
Fixes#801.
Go 1.21.0 was released in August 2023, so our upcoming release
will no longer support the Go 1.20 release series.
The first Go 1.22 release candidate is also due in December 2023,
less than a month from now, so dropping 1.20 will simplify 1.22 work.
