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fix(skills): prevent path traversal in LocalSkillSource via normalize + boundary check #1311

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fix(skills): prevent path traversal in LocalSkillSource via normalize + boundary check #1311

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25 changes: 22 additions & 3 deletions core/src/main/java/com/google/adk/skills/LocalSkillSource.java
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Original file line number Diff line number Diff line change
Expand Up @@ -45,12 +45,21 @@ public LocalSkillSource(Path skillsBasePath) {

@Override
public Single<ImmutableList<String>> listResources(String skillName, String resourceDirectory) {
Path skillDir = skillsBasePath.resolve(skillName);
Path skillDir = skillsBasePath.resolve(skillName).normalize();
if (!isDirectory(skillDir)) {
return Single.error(
new SkillSourceException("Skill not found: " + skillName, SKILL_NOT_FOUND));
}
Path resourceDir = skillDir.resolve(resourceDirectory);
Path resourceDir = skillDir.resolve(resourceDirectory).normalize();
// Prevent path traversal: the resolved resource directory must remain inside
// the skill's own directory. A raw string prefix check on the input is not
// sufficient because "references/../../../../etc" bypasses it.
if (!resourceDir.startsWith(skillDir)) {
return Single.error(
new SkillSourceException(
"Path traversal detected in resource directory: " + resourceDirectory,
RESOURCE_NOT_FOUND));
}
if (!isDirectory(resourceDir)) {
return Single.error(
new SkillSourceException(
Expand Down Expand Up @@ -96,7 +105,17 @@ protected Flowable<SkillMdPath<Path>> listSkills() {

@Override
protected Single<Path> findResourcePath(String skillName, String resourcePath) {
Path file = skillsBasePath.resolve(skillName).resolve(resourcePath);
Path base = skillsBasePath.resolve(skillName).normalize();
Path file = base.resolve(resourcePath).normalize();
// Enforce boundary: the resolved path must remain inside the skill's base
// directory. Without this check, a payload like
// "references/../../../../etc/passwd" passes the startsWith("references/")
// prefix check in LoadSkillResourceTool but resolves outside skillsBasePath.
if (!file.startsWith(base)) {
return Single.error(
new SkillSourceException(
"Path traversal detected: " + resourcePath, RESOURCE_NOT_FOUND));
}
if (!Files.exists(file)) {
return Single.error(
new SkillSourceException("Resource not found: " + file, RESOURCE_NOT_FOUND));
Expand Down