From 5372a243758bd6f85f5d461915be55d9bc160b3f Mon Sep 17 00:00:00 2001
From: Ken Chen <cken@google.com>
Date: Thu, 7 Jul 2022 17:48:06 +0800
Subject: [PATCH] Disallow '_' in bpf source name

Current design:
1. The bpf compiled object name is derived from the source name
   (e.g. foo.c -> foo.o).
2. Full bpf program/map name are concatenated by object name + '_' +
   program/map name in run-time. (e.g. obj name: x.o; program name: y_z;
   full bpf program name will be x_y_z)

Issue:
x.o with map y_z and x_y.o with map z can cause naming collision in
run-time, since both result in x_y_z. This commit prevents it from
happening with a build-time check.

Bug: 236706995
Test: m
Change-Id: Ic03bfcf07a5748ed63246b71d5ae8de0405e658a
---
 apex/apex_test.go | 18 +++++++++---------
 bpf/bpf.go        |  4 ++++
 bpf/bpf_test.go   | 17 +++++++++++++++--
 3 files changed, 28 insertions(+), 11 deletions(-)

diff --git a/apex/apex_test.go b/apex/apex_test.go
index dbe918010..dc505b4fa 100644
--- a/apex/apex_test.go
+++ b/apex/apex_test.go
@@ -619,7 +619,7 @@ func TestDefaults(t *testing.T) {
 			java_libs: ["myjar"],
 			apps: ["AppFoo"],
 			rros: ["rro"],
-			bpfs: ["bpf", "netd_test"],
+			bpfs: ["bpf", "netdTest"],
 			updatable: false,
 		}
 
@@ -673,8 +673,8 @@ func TestDefaults(t *testing.T) {
 		}
 
 		bpf {
-			name: "netd_test",
-			srcs: ["netd_test.c"],
+			name: "netdTest",
+			srcs: ["netdTest.c"],
 			sub_dir: "netd",
 		}
 
@@ -687,7 +687,7 @@ func TestDefaults(t *testing.T) {
 		"overlay/blue/rro.apk",
 		"etc/bpf/bpf.o",
 		"etc/bpf/bpf2.o",
-		"etc/bpf/netd/netd_test.o",
+		"etc/bpf/netd/netdTest.o",
 	})
 }
 
@@ -6151,7 +6151,7 @@ func TestOverrideApex(t *testing.T) {
 			name: "override_myapex",
 			base: "myapex",
 			apps: ["override_app"],
-			bpfs: ["override_bpf"],
+			bpfs: ["overrideBpf"],
 			prebuilts: ["override_myetc"],
 			bootclasspath_fragments: ["override_bootclasspath_fragment"],
 			systemserverclasspath_fragments: ["override_systemserverclasspath_fragment"],
@@ -6201,8 +6201,8 @@ func TestOverrideApex(t *testing.T) {
 		}
 
 		bpf {
-			name: "override_bpf",
-			srcs: ["override_bpf.c"],
+			name: "overrideBpf",
+			srcs: ["overrideBpf.c"],
 		}
 
 		prebuilt_etc {
@@ -6305,7 +6305,7 @@ func TestOverrideApex(t *testing.T) {
 	ensureContains(t, copyCmds, "image.apex/app/override_app@TEST.BUILD_ID/override_app.apk")
 
 	ensureNotContains(t, copyCmds, "image.apex/etc/bpf/bpf.o")
-	ensureContains(t, copyCmds, "image.apex/etc/bpf/override_bpf.o")
+	ensureContains(t, copyCmds, "image.apex/etc/bpf/overrideBpf.o")
 
 	ensureNotContains(t, copyCmds, "image.apex/etc/myetc")
 	ensureContains(t, copyCmds, "image.apex/etc/override_myetc")
@@ -6339,7 +6339,7 @@ func TestOverrideApex(t *testing.T) {
 	data.Custom(&builder, name, "TARGET_", "", data)
 	androidMk := builder.String()
 	ensureContains(t, androidMk, "LOCAL_MODULE := override_app.override_myapex")
-	ensureContains(t, androidMk, "LOCAL_MODULE := override_bpf.o.override_myapex")
+	ensureContains(t, androidMk, "LOCAL_MODULE := overrideBpf.o.override_myapex")
 	ensureContains(t, androidMk, "LOCAL_MODULE := apex_manifest.pb.override_myapex")
 	ensureContains(t, androidMk, "LOCAL_MODULE := override_bcplib.override_myapex")
 	ensureContains(t, androidMk, "LOCAL_MODULE := override_systemserverlib.override_myapex")
diff --git a/bpf/bpf.go b/bpf/bpf.go
index 14b2d84c5..5d2533fc2 100644
--- a/bpf/bpf.go
+++ b/bpf/bpf.go
@@ -17,6 +17,7 @@ package bpf
 import (
 	"fmt"
 	"io"
+	"path/filepath"
 	"strings"
 
 	"android/soong/android"
@@ -154,6 +155,9 @@ func (bpf *bpf) GenerateAndroidBuildActions(ctx android.ModuleContext) {
 	srcs := android.PathsForModuleSrc(ctx, bpf.properties.Srcs)
 
 	for _, src := range srcs {
+		if strings.ContainsRune(filepath.Base(src.String()), '_') {
+			ctx.ModuleErrorf("invalid character '_' in source name")
+		}
 		obj := android.ObjPathWithExt(ctx, "unstripped", src, "o")
 
 		ctx.Build(pctx, android.BuildParams{
diff --git a/bpf/bpf_test.go b/bpf/bpf_test.go
index 51fbc15e1..6e3909680 100644
--- a/bpf/bpf_test.go
+++ b/bpf/bpf_test.go
@@ -30,8 +30,9 @@ var prepareForBpfTest = android.GroupFixturePreparers(
 	cc.PrepareForTestWithCcDefaultModules,
 	android.FixtureMergeMockFs(
 		map[string][]byte{
-			"bpf.c":       nil,
-			"BpfTest.cpp": nil,
+			"bpf.c":              nil,
+			"bpf_invalid_name.c": nil,
+			"BpfTest.cpp":        nil,
 		},
 	),
 	PrepareForTestWithBpf,
@@ -58,3 +59,15 @@ func TestBpfDataDependency(t *testing.T) {
 	// value is not available for testing from this package.
 	// TODO(jungjw): Add a check for data or move this test to the cc package.
 }
+
+func TestBpfSourceName(t *testing.T) {
+	bp := `
+		bpf {
+			name: "bpf_invalid_name.o",
+			srcs: ["bpf_invalid_name.c"],
+		}
+	`
+	prepareForBpfTest.ExtendWithErrorHandler(android.FixtureExpectsOneErrorPattern(
+		`\QAndroid.bp:2:3: module "bpf_invalid_name.o" variant "android_common": invalid character '_' in source name\E`)).
+		RunTestWithBp(t, bp)
+}