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Avoid exceptions from hermetic sandbox for unsupported artifact subcl…
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…asses

Avoid exceptions from linux hermetic sandbox for unsupported FileArtifactValue subclasses.

Also adds test cases to confirm no regression of existing functionality.

Fixes bazelbuild#15340

Closes bazelbuild#16739.

Change-Id: I0f1373f6f99328b8277fe1cec87d3946b83481c1
PiperOrigin-RevId: 490490477
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ulrfa authored and copybara-github committed Nov 23, 2022
1 parent b6c2904 commit e2bc237
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Showing 2 changed files with 233 additions and 14 deletions.
Original file line number Diff line number Diff line change
Expand Up @@ -66,6 +66,8 @@ final class LinuxSandboxedSpawnRunner extends AbstractSandboxSpawnRunner {
private static final Map<Path, Boolean> isSupportedMap = new HashMap<>();
private static final AtomicBoolean warnedAboutNonHermeticTmp = new AtomicBoolean();

private static final AtomicBoolean warnedAboutUnsupportedModificationCheck = new AtomicBoolean();

/**
* Returns whether the linux sandbox is supported on the local machine by running a small command
* in it.
Expand Down Expand Up @@ -216,9 +218,7 @@ protected SandboxedSpawn prepareSpawn(Spawn spawn, SpawnExecutionContext context
ImmutableSet<Path> writableDirs = getWritableDirs(sandboxExecRoot, environment);

SandboxInputs inputs =
helpers.processInputFiles(
context.getInputMapping(PathFragment.EMPTY_FRAGMENT),
execRoot);
helpers.processInputFiles(context.getInputMapping(PathFragment.EMPTY_FRAGMENT), execRoot);
SandboxOutputs outputs = helpers.getOutputs(spawn);

Duration timeout = context.getTimeout();
Expand Down Expand Up @@ -439,22 +439,39 @@ private void checkForConcurrentModifications(SpawnExecutionContext context)
throws IOException, ForbiddenActionInputException {
for (ActionInput input : context.getInputMapping(PathFragment.EMPTY_FRAGMENT).values()) {
if (input instanceof VirtualActionInput) {
// Virtual inputs are not existing in file system and can't be tampered with via sandbox. No
// need to check them.
continue;
}

FileArtifactValue metadata = context.getMetadataProvider().getMetadata(input);
Path path = execRoot.getRelative(input.getExecPath());
if (!metadata.getType().isFile()) {
// The hermetic sandbox creates hardlinks from files inside sandbox to files outside
// sandbox. The content of the files outside the sandbox could have been tampered with via
// the hardlinks. Therefore files are checked for modifications. But directories and
// unresolved symlinks are not represented as hardlinks in sandbox and don't need to be
// checked. By continue and not checking them, we avoid UnsupportedOperationException and
// IllegalStateException.
continue;
}

Path path = execRoot.getRelative(input.getExecPath());
try {
if (wasModifiedSinceDigest(metadata.getContentsProxy(), path)) {
throw new IOException("input dependency " + path + " was modified during execution.");
}
} catch (UnsupportedOperationException e) {
throw new IOException(
"input dependency "
+ path
+ " could not be checked for modifications during execution.",
e);
// Some FileArtifactValue implementations are ignored safely and silently already by the
// isFile check above. The remaining ones should probably be checked, but some are not
// supporting necessary operations.
if (warnedAboutUnsupportedModificationCheck.compareAndSet(false, true)) {
reporter.handle(
Event.warn(
String.format(
"Input dependency %s of type %s could not be checked for modifications during"
+ " execution. Suppressing similar warnings.",
path, metadata.getClass().getSimpleName())));
}
}
}
}
Expand Down
212 changes: 207 additions & 5 deletions src/test/shell/bazel/bazel_hermetic_sandboxing_test.sh
Original file line number Diff line number Diff line change
Expand Up @@ -95,6 +95,37 @@ import import_module
EOF

cat << 'EOF' > examples/hermetic/BUILD
load(
"test.bzl",
"overwrite_via_symlink",
"overwrite_file_from_declared_directory",
"subdirectories_in_declared_directory",
"other_artifacts",
)
overwrite_via_symlink(
name = "overwrite_via_resolved_symlink",
resolve_symlink = True
)
overwrite_via_symlink(
name = "overwrite_via_unresolved_symlink",
resolve_symlink = False
)
overwrite_file_from_declared_directory(
name = "overwrite_file_from_declared_directory"
)
subdirectories_in_declared_directory(
name = "subdirectories_in_declared_directory"
)
other_artifacts(
name = "other_artifacts"
)
genrule(
name = "absolute_path",
srcs = ["script_absolute_path.sh"], # unknown_file.txt not referenced.
Expand Down Expand Up @@ -129,6 +160,141 @@ genrule(
(echo overwrite text > $(location :input_file)) && \
(echo success > $@)) || (echo fail > $@)",
)
EOF

cat << 'EOF' > examples/hermetic/test.bzl
def _overwrite_via_symlink_impl(ctx):
file = ctx.actions.declare_file(ctx.attr.name + ".file")
if ctx.attr.resolve_symlink:
symlink = ctx.actions.declare_file(ctx.attr.name + ".symlink")
else:
symlink = ctx.actions.declare_symlink(ctx.attr.name + ".symlink")
ctx.actions.write(file, "")
if ctx.attr.resolve_symlink:
ctx.actions.symlink(
output = symlink,
target_file = file
)
# Symlink become resolved to RegularFileArtifactValue.
needed_inputs = [symlink]
else:
ctx.actions.symlink(
output = symlink,
target_path = file.basename
)
# Symlink become UnresolvedSymlinkArtifactValue and would be
# dangling unless also providing the actual file as input to sandbox.
needed_inputs = [symlink, file]
result_file = ctx.actions.declare_file(ctx.attr.name + ".result")
# Try invalid write to the input file via the symlink
ctx.actions.run_shell(
command = "chmod u+w $1 && echo hello >> $1 && ls -lR > $2",
arguments = [symlink.path, result_file.path],
inputs = needed_inputs,
outputs = [result_file],
)
return [DefaultInfo(files = depset([result_file]))]
overwrite_via_symlink = rule(
attrs = {
"resolve_symlink" : attr.bool(),
},
implementation = _overwrite_via_symlink_impl,
)
def _overwrite_file_from_declared_directory_impl(ctx):
dir = ctx.actions.declare_directory(ctx.attr.name + ".dir")
ctx.actions.run_shell(
command = "mkdir -p $1/subdir && touch $1/subdir/file",
arguments = [dir.path],
outputs = [dir],
)
# Try invalid write to input file, with file as implicit input
# from declared directory.
result_file = ctx.actions.declare_file(ctx.attr.name + ".result")
ctx.actions.run_shell(
command = "chmod -R u+w $1 && echo hello >> $1/subdir/file && touch $2",
arguments = [dir.path, result_file.path],
inputs = [dir],
outputs = [result_file],
)
return [DefaultInfo(files = depset([result_file]))]
overwrite_file_from_declared_directory = rule(
implementation = _overwrite_file_from_declared_directory_impl,
)
def _subdirectories_in_declared_directory_impl(ctx):
dir = ctx.actions.declare_directory(ctx.attr.name + ".dir")
ctx.actions.run_shell(
command = "mkdir -p %s/subdir1/subdir2" % dir.path,
outputs = [dir],
)
result_file = ctx.actions.declare_file(ctx.attr.name + ".result")
ctx.actions.run_shell(
command = "ls -lRH %s > %s" % (dir.path, result_file.path),
inputs = [dir],
outputs = [result_file],
)
return [DefaultInfo(files = depset([result_file]))]
subdirectories_in_declared_directory = rule(
implementation = _subdirectories_in_declared_directory_impl,
)
def _other_artifacts_impl(ctx):
# Produce artifacts of other types
regular_file_artifact = ctx.actions.declare_file(ctx.attr.name + ".regular_file_artifact")
directory_artifact = ctx.actions.declare_file(ctx.attr.name + ".directory_artifact")
tree_artifact = ctx.actions.declare_directory(ctx.attr.name + ".tree_artifact")
unresolved_symlink_artifact = ctx.actions.declare_symlink(ctx.attr.name + ".unresolved_symlink_artifact")
ctx.actions.run_shell(
command = "touch %s && mkdir %s" % (regular_file_artifact.path, directory_artifact.path),
outputs = [regular_file_artifact, tree_artifact, directory_artifact],
)
ctx.actions.symlink(
output = unresolved_symlink_artifact,
target_path="dangling"
)
# Test other artifact types as input to hermetic sandbox.
all_artifacts = [regular_file_artifact,
directory_artifact,
tree_artifact,
unresolved_symlink_artifact]
input_paths_string = " ".join([a.path for a in all_artifacts])
result_file = ctx.actions.declare_file(ctx.attr.name + ".result")
ctx.actions.run_shell(
command = "ls -lR %s > %s" % (input_paths_string, result_file.path),
inputs = all_artifacts,
outputs = [result_file],
)
return [DefaultInfo(files = depset([result_file]))]
other_artifacts = rule(
implementation = _other_artifacts_impl,
)
EOF
}

Expand All @@ -141,17 +307,13 @@ function test_absolute_path() {

# Test that the build can't escape the sandbox by resolving symbolic link.
function test_symbolic_link() {
[ "$PLATFORM" != "darwin" ] || return 0

bazel build examples/hermetic:symbolic_link &> $TEST_log \
&& fail "Fail due to non hermetic sandbox: examples/hermetic:symbolic_link" || true
expect_log "cat: \/execroot\/main\/examples\/hermetic\/unknown_file.txt: No such file or directory"
}

# Test that the sandbox discover if the bazel python rule miss dependencies.
function test_missing_python_deps() {
[ "$PLATFORM" != "darwin" ] || return 0

bazel test examples/hermetic:py_module_test --test_output=all &> $TEST_TMPDIR/log \
&& fail "Fail due to non hermetic sandbox: examples/hermetic:py_module_test" || true

Expand All @@ -160,7 +322,6 @@ function test_missing_python_deps() {

# Test that the intermediate corrupt input file gets re:evaluated
function test_writing_input_file() {
[ "$PLATFORM" != "darwin" ] || return 0
# Write an input file, this should cause the hermetic sandbox to fail with an exception
bazel build examples/hermetic:write_input_test &> $TEST_log \
&& fail "Fail due to non hermetic sandbox: examples/hermetic:write_input_test" || true
Expand All @@ -177,7 +338,48 @@ function test_writing_input_file() {
expect_log "original text input"
}

# Test that invalid write of input file is detected, when file is accessed via resolved symlink.
function test_overwrite_via_resolved_symlink() {
bazel build examples/hermetic:overwrite_via_resolved_symlink &> $TEST_log \
&& fail "Hermetic sandbox did not detect invalid write to input file"
expect_log "input dependency .* was modified during execution."
}

# Test that invalid write of input file is detected, when file is accessed via unresolved symlink.
function test_overwrite_via_unresolved_symlink() {
bazel build examples/hermetic:overwrite_via_unresolved_symlink &> $TEST_log \
&& fail "Hermetic sandbox did not detect invalid write to input file"
expect_log "input dependency .* was modified during execution."
}

# Test that invalid write of input file is detected, when file is found implicit via declared directory.
function test_overwrite_file_from_declared_directory() {
bazel build examples/hermetic:overwrite_file_from_declared_directory &> $TEST_log \
&& fail "Hermetic sandbox did not detect invalid write to input file"
expect_log "input dependency .* was modified during execution."
}

# Test that the sandbox can handle deep directory trees from declared directory.
function test_subdirectories_in_declared_directory() {
bazel build examples/hermetic:subdirectories_in_declared_directory &> $TEST_log
cat bazel-bin/examples/hermetic/subdirectories_in_declared_directory.result
assert_contains "dir/subdir1/subdir2" "bazel-bin/examples/hermetic/subdirectories_in_declared_directory.result"
}

# Test that the sandbox is not crashing and not producing warnings for various types of artifacts.
# Regression test for Issue #15340
function test_other_artifacts() {
bazel shutdown # Clear memory about duplicated warnings
bazel build examples/hermetic:other_artifacts &> $TEST_log
expect_not_log "WARNING"
assert_contains "regular_file_artifact" "bazel-bin/examples/hermetic/other_artifacts.result"
assert_contains "unresolved_symlink_artifact" "bazel-bin/examples/hermetic/other_artifacts.result"
assert_contains "directory_artifact" "bazel-bin/examples/hermetic/other_artifacts.result"
assert_contains "tree_artifact" "bazel-bin/examples/hermetic/other_artifacts.result"
}

# The test shouldn't fail if the environment doesn't support running it.
check_sandbox_allowed || exit 0
[ "$PLATFORM" != "darwin" ] || exit 0

run_suite "hermetic_sandbox"

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