The trash block generator docs aren't ready yet, they will come soon.
This is not a release blocker, given that the control flow obfuscator
is experimental and opt-in for now.
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 early December, a new internal package linknamed from runtime
was introduced, internal/chacha8rand. Re-generate the tables.
Note that due to the same group of CLs and refactors,
math/rand and net are no longer linknamed from runtime in Go 1.22.
They are still in Go 1.21, so keep those entries around for now.
We can remove math/rand/v2, as it doesn't yet exist in 1.21.
Fixes#820.
In some cases, compiler could optimize the shuffle obfuscator,
causing exposing the obfuscated literal.
As a fix, added xor encryption of array indexes.
This type of question has popped up a number of times before,
particularly when someone unfamiliar with obfuscators in other languages
first hears about the existence of one for Go.
The Go 1.21 linker patches luckily rebased on master as of
de5b418bea70aaf27de1f47e9b5813940d1e15a4 just fine.
The addition of the strings import in the second patch was removed,
since the file in Go 1.22 now has this package import.
We can remove the Go 1.20 linker patches too, since we no longer support
that Go version in the upcoming release.
Start treating runtime/internal/startlinetest as part of the runtime,
since otherwise its test-only trickery breaks "garble build std":
# runtime/internal/startlinetest
[...]/XS7r7lPHkTG.s:23: ABI selector only permitted when compiling runtime, reference was to "HGoWHDsKwh.AlfA2or7Nnb"
asm: assembly of $WORK/.tmp/garble-shared1535203339/HGoWHDsKwh/XS7r7lPHkTG.s failed
While here, update actions/checkout and staticcheck in CI.
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.
Two new packages linknamed with the runtime package,
one new intrinsic function, and one that is being removed in Go 1.22
but we want to keep around as long as we support Go 1.21.
Also note that, since math/rand/v2 simply does not exist until Go 1.22,
we need to adjust appendListedPackages to not fail on older versions.
Otherwise we have to update that `@semver` string
alongside the regular x/tools updates in go.mod.
There's no reason to separate the two versions either.
Without hardening, obfuscation is vulnerable to analysis via symbolic
execution because all keys are opened, and it is easy to trace their
connections. Added extendable (contribution-friendly) hardening
mechanism that makes it harder to determine relationship between key and
execution block through key obfuscation.
There are 2 hardeners implemented and both are compatible with literal
obfuscation, which can make analysis even more difficult.
We were using an alphabet with a duplicate character on purpose.
Go 1.21 was perfectly fine with that, but 1.22 started noticing:
panic: encoding alphabet includes duplicate symbols
I can't fault the new sanity check, because it makes sense in general.
What we are doing here is slightly bizarre, because we don't care
about decoding the name hashes at all.
Appease the sanity check by replacing dashes with duplicate characters
as a follow-up step. While here, use "a" rather than "z",
which is more common and less likely to be noticeable.
On my laptop, `go test -short -race` on Go 1.20 used to take about 62s.
Jumping to Go 1.21, I was surprised to see an increase to 152s,
more than double - which was weird given how often the CPU was idle.
This manifested when updating our CI to start testing on Go 1.21.
Where Go 1.20 on Linux took about 10m to run `go test -race`,
Go 1.21 hit the 20m timeout every single time.
After a bit of googling, I was reminded of https://go.dev/issues/20364
as well as https://go.dev/doc/articles/race_detector#Options:
atexit_sleep_ms (default 1000): Amount of milliseconds to sleep in the main goroutine before exiting.
This default is a bit aggressive for Go, but usually harmless,
having each test binary sleep for 1s after the package has been tested.
However, this 1s sleep after main runs is horrendous for garble's tests;
the testscripts run `garble build` many times, running the test binary.
It then runs `go build -toolexec=garble`, which runs the test binary
many more times: for every compiler, linker, etc invocation.
This means that our testscripts would include dozens of 1s sleeps,
in many cases blocking the continuation of the entire test.
This seemed to not be happening on earlier Go versions due to a bug;
Go 1.21's race mode started obeying this default properly.
The added change sets atexit_sleep_ms to something more reasonable
if GORACE isn't set at all; 10ms doesn't disable this check entirely,
but its overhead is orders of magnitude less noticeable than 1000ms.
`go test -short -race` on Go 1.21 drops back down to 68s for me.
Up until now, the new SSA reflection detection relied on call sites
to propagate which objects (named types, struct fields) used reflection.
For example, given the code:
json.Marshal(new(T))
we would first record that json.Marshal calls reflect.TypeOf,
and then that the user's code called json.Marshal with the type *T.
However, this would not catch a slight variation on the above:
var t T
reflect.TypeOf(t)
t.foo = struct{bar int}{}
Here, type T's fields such as "foo" and "bar" are not obfuscated,
since our logic sees the call site and marks the type T recursively.
However, the unnamed `struct{bar int}` type was still obfuscated,
causing errors such as:
cannot use struct{uKGvcJvD24 int}{} (value of type struct{uKGvcJvD24 int}) as struct{bar int} value in assignment
The solution is to teach the analysis about *ssa.Store instructions
in a similar way to how it already knows about *ssa.Call instructions.
If we see a store where the destination type is marked for reflection,
then we mark the source type as well, fixing the bug above.
This fixes obfuscating github.com/gogo/protobuf/proto.
A number of other Go modules fail with similar errors,
and they look like very similar bugs,
but this particular fix doesn't apply to them.
Future incremental fixes will try to deal with those extra cases.
Fixes#685.
We were recently altering the logic in reflect.go for type names,
which could have broken this kind of valid use of reflection.
Add a regression test, which I verified would break before my last
change to "simplify" the logic, which actually changed the logic,
as xuannv112 correctly pointed out.
After thinking about the change in behavior for a little while,
I realised that the new behavior is more correct, hence the test.
Update CI to use a newer version of Go master,
now that we're already getting release candidates.
Look at the diffs between Go 1.20 and master of `go help build`
and `go help testflag`, and add two flags that were recently added.
While here, bump a hopeful TODO for a feature request,
since that one definitely did not happen for 1.21.
A recent PR added a bigger regression test for go-spew,
and fixed an issue where we would obfuscate local named types
even if they were embedded into local structs used for reflection.
This would effectively mean we were obfuscating one field name,
the one derived from the embedding, which we didn't want to.
The fix did this by searching for embedded objects with extra code.
However, as far as I can tell, that isn't necessary;
we can do the right thing by recording all local type names
just like we already do for all field names.
This results in less complicated code, and avoids needing special logic
to handle embedding struct types, so I reckon it's a win.
Add even more tests to convince myself that we're still obfuscating
local types and field names which aren't used for reflection.
The script has been updated to include the actual count of files
with CRLF endings found.
The exit status of the script now accurately reflects the number of
files with incorrect line endings.
Starting to explain new features in more detail.
A bullet list of single lines can be enough for most bug fixes,
but some of the big refactors like SSA or caching need some context.
First, teach scripts/gen-go-std-tables.sh to omit test packages,
since runtime/metrics_test would always result in an error.
Instead, make transformLinkname explicitly skip that package,
leaving a comment about a potential improvement if needed.
Second, the only remaining "not found" error we had was "maps" on 1.20,
so rewrite that check based on ImportPath and GoVersionSemver.
Third, detect packages with the "exclude all Go files" error
by looking at CompiledGoFiles and IgnoredGoFiles, which is less brittle.
This means that we are no longer doing any filtering on pkg.Error.Err,
which means we are less likely to break with Go error message changes.
Fourth, the check on pkg.Incomplete is now obsolete given the above,
meaning that the CompiledGoFiles length check is plenty.
Finally, stop trying to be clever about how we print errors.
Now that we're no longer skipping packages based on pkg.Error values,
printing pkg.DepsErrors was causing duplicate messages in the output.
Simply print pkg.Error values with only minimal tweaks:
including the position if there is any, and avoiding double newlines.
Overall, this makes our logic a lot less complicated,
and garble still works the way we want it to.
Daniel Martí
pagran
Paul Scheduikat
Mrs4s
Hritik Vijay
xuannv
Emmanuel Chee-zaram Okeke