build: add nogo for static validation

PiperOrigin-RevId: 257297820

BUILD

@@ -1,6 +1,6 @@
 package(licenses = ["notice"])  # Apache 2.0
 
-load("@io_bazel_rules_go//go:def.bzl", "go_path")
+load("@io_bazel_rules_go//go:def.bzl", "go_path", "nogo")
 load("@bazel_gazelle//:def.bzl", "gazelle")
 
 # The sandbox filegroup is used for sandbox-internal dependencies.
@@ -29,3 +29,15 @@ go_path(
 # To update the WORKSPACE from go.mod, use:
 #   bazel run //:gazelle -- update-repos -from_file=go.mod
 gazelle(name = "gazelle")
+
+# nogo applies checks to all Go source in this repository, enforcing code
+# guidelines and restrictions. Note that the tool libraries themselves should
+# live in the tools subdirectory (unless they are standard).
+nogo(
+    name = "nogo",
+    config = "tools/nogo.js",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//tools/checkunsafe",
+    ],
+)

WORKSPACE

@@ -20,7 +20,10 @@ load("@io_bazel_rules_go//go:deps.bzl", "go_rules_dependencies", "go_register_to
 
 go_rules_dependencies()
 
-go_register_toolchains(go_version = "1.12.6")
+go_register_toolchains(
+    go_version = "1.12.6",
+    nogo = "@//:nogo",
+)
 
 load("@bazel_gazelle//:deps.bzl", "gazelle_dependencies", "go_repository")
 
@@ -141,6 +144,12 @@ go_repository(
     importpath = "golang.org/x/sys",
 )
 
+go_repository(
+    name = "org_golang_x_tools",
+    commit = "aa82965741a9fecd12b026fbb3d3c6ed3231b8f8",
+    importpath = "golang.org/x/tools",
+)
+
 go_repository(
     name = "com_github_google_btree",
     importpath = "github.com/google/btree",

pkg/sentry/kernel/BUILD

@@ -31,7 +31,7 @@ go_template_instance(
 
 go_template_instance(
     name = "seqatomic_taskgoroutineschedinfo",
-    out = "seqatomic_taskgoroutineschedinfo.go",
+    out = "seqatomic_taskgoroutineschedinfo_unsafe.go",
     package = "kernel",
     suffix = "TaskGoroutineSchedInfo",
     template = "//third_party/gvsync:generic_seqatomic",
@@ -112,7 +112,7 @@ go_library(
         "ptrace_arm64.go",
         "rseq.go",
         "seccomp.go",
-        "seqatomic_taskgoroutineschedinfo.go",
+        "seqatomic_taskgoroutineschedinfo_unsafe.go",
         "session_list.go",
         "sessions.go",
         "signal.go",

pkg/sentry/kernel/auth/BUILD

@@ -5,7 +5,7 @@ load("//tools/go_stateify:defs.bzl", "go_library")
 
 go_template_instance(
     name = "atomicptr_credentials",
-    out = "atomicptr_credentials.go",
+    out = "atomicptr_credentials_unsafe.go",
     package = "auth",
     suffix = "Credentials",
     template = "//third_party/gvsync:generic_atomicptr",
@@ -45,7 +45,7 @@ go_template_instance(
 go_library(
     name = "auth",
     srcs = [
-        "atomicptr_credentials.go",
+        "atomicptr_credentials_unsafe.go",
         "auth.go",
         "capability_set.go",
         "context.go",

pkg/sentry/kernel/futex/BUILD

@@ -5,7 +5,7 @@ load("//tools/go_stateify:defs.bzl", "go_library", "go_test")
 
 go_template_instance(
     name = "atomicptr_bucket",
-    out = "atomicptr_bucket.go",
+    out = "atomicptr_bucket_unsafe.go",
     package = "futex",
     suffix = "Bucket",
     template = "//third_party/gvsync:generic_atomicptr",
@@ -29,7 +29,7 @@ go_template_instance(
 go_library(
     name = "futex",
     srcs = [
-        "atomicptr_bucket.go",
+        "atomicptr_bucket_unsafe.go",
         "futex.go",
         "waiter_list.go",
     ],

pkg/sentry/time/BUILD

@@ -6,7 +6,7 @@ load("//tools/go_generics:defs.bzl", "go_template_instance")
 
 go_template_instance(
     name = "seqatomic_parameters",
-    out = "seqatomic_parameters.go",
+    out = "seqatomic_parameters_unsafe.go",
     package = "time",
     suffix = "Parameters",
     template = "//third_party/gvsync:generic_seqatomic",
@@ -27,7 +27,7 @@ go_library(
         "parameters.go",
         "sampler.go",
         "sampler_unsafe.go",
-        "seqatomic_parameters.go",
+        "seqatomic_parameters_unsafe.go",
         "tsc_amd64.s",
         "tsc_arm64.s",
     ],

third_party/gvsync/atomicptrtest/BUILD

@@ -6,7 +6,7 @@ load("//tools/go_generics:defs.bzl", "go_template_instance")
 
 go_template_instance(
     name = "atomicptr_int",
-    out = "atomicptr_int.go",
+    out = "atomicptr_int_unsafe.go",
     package = "atomicptr",
     suffix = "Int",
     template = "//third_party/gvsync:generic_atomicptr",
@@ -17,7 +17,7 @@ go_template_instance(
 
 go_library(
     name = "atomicptr",
-    srcs = ["atomicptr_int.go"],
+    srcs = ["atomicptr_int_unsafe.go"],
     importpath = "gvisor.dev/gvisor/third_party/gvsync/atomicptr",
 )
 

third_party/gvsync/seqatomictest/BUILD

@@ -6,7 +6,7 @@ load("//tools/go_generics:defs.bzl", "go_template_instance")
 
 go_template_instance(
     name = "seqatomic_int",
-    out = "seqatomic_int.go",
+    out = "seqatomic_int_unsafe.go",
     package = "seqatomic",
     suffix = "Int",
     template = "//third_party/gvsync:generic_seqatomic",
@@ -17,7 +17,7 @@ go_template_instance(
 
 go_library(
     name = "seqatomic",
-    srcs = ["seqatomic_int.go"],
+    srcs = ["seqatomic_int_unsafe.go"],
     importpath = "gvisor.dev/gvisor/third_party/gvsync/seqatomic",
     deps = [
         "//third_party/gvsync",

tools/checkunsafe/BUILD

@@ -0,0 +1,13 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_tool_library")
+
+package(licenses = ["notice"])
+
+go_tool_library(
+    name = "checkunsafe",
+    srcs = ["check_unsafe.go"],
+    importpath = "checkunsafe",
+    visibility = ["//visibility:public"],
+    deps = [
+        "@org_golang_x_tools//go/analysis:go_tool_library",
+    ],
+)

tools/checkunsafe/check_unsafe.go

@@ -0,0 +1,56 @@
+// Copyright 2019 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package checkunsafe allows unsafe imports only in files named appropriately.
+package checkunsafe
+
+import (
+	"fmt"
+	"path"
+	"strconv"
+	"strings"
+
+	"golang.org/x/tools/go/analysis"
+)
+
+// Analyzer defines the entrypoint.
+var Analyzer = &analysis.Analyzer{
+	Name: "checkunsafe",
+	Doc:  "allows unsafe use only in specified files",
+	Run:  run,
+}
+
+func run(pass *analysis.Pass) (interface{}, error) {
+	for _, f := range pass.Files {
+		for _, imp := range f.Imports {
+			// Is this an unsafe import?
+			pkg, err := strconv.Unquote(imp.Path.Value)
+			if err != nil || pkg != "unsafe" {
+				continue
+			}
+
+			// Extract the filename.
+			filename := pass.Fset.File(imp.Pos()).Name()
+
+			// Allow files named _unsafe.go or _test.go to opt out.
+			if strings.HasSuffix(filename, "_unsafe.go") || strings.HasSuffix(filename, "_test.go") {
+				continue
+			}
+
+			// Throw the error.
+			pass.Reportf(imp.Pos(), fmt.Sprintf("package unsafe imported by %s; must end with _unsafe.go", path.Base(filename)))
+		}
+	}
+	return nil, nil
+}

tools/nogo.js

@@ -0,0 +1,7 @@
+{
+  "checkunsafe": {
+    "exclude_files": {
+      "/external/": "not subject to constraint"
+    }
+  }
+}