Merge "init: Drop inheritable capabilities when switching uids"

am: a227804015

Change-Id: I2d720e330e7043434e198ef455a8f340dd57b95d

init/capabilities.cpp

@@ -194,5 +194,18 @@ bool SetCapsForExec(const CapSet& to_keep) {
     return SetAmbientCaps(to_keep);
 }
 
+bool DropInheritableCaps() {
+    ScopedCaps caps(cap_get_proc());
+    if (cap_clear_flag(caps.get(), CAP_INHERITABLE) == -1) {
+        PLOG(ERROR) << "cap_clear_flag(INHERITABLE) failed";
+        return false;
+    }
+    if (cap_set_proc(caps.get()) != 0) {
+        PLOG(ERROR) << "cap_set_proc() failed";
+        return false;
+    }
+    return true;
+}
+
 }  // namespace init
 }  // namespace android

init/capabilities.h

@@ -35,6 +35,7 @@ int LookupCap(const std::string& cap_name);
 bool CapAmbientSupported();
 unsigned int GetLastValidCap();
 bool SetCapsForExec(const CapSet& to_keep);
+bool DropInheritableCaps();
 
 }  // namespace init
 }  // namespace android

init/service.cpp

@@ -291,6 +291,11 @@ void Service::SetProcessAttributes() {
         if (!SetCapsForExec(capabilities_)) {
             LOG(FATAL) << "cannot set capabilities for " << name_;
         }
+    } else if (uid_) {
+        // Inheritable caps can be non-zero when running in a container.
+        if (!DropInheritableCaps()) {
+            LOG(FATAL) << "cannot drop inheritable caps for " << name_;
+        }
     }
 }