Merge "adb: Correctly drop caps when ambient capabilities are used" am: 44f78bed19 (39eaab78) · Commits · e / os / android_system_core

adb/daemon/main.cpp

+29 −4

Original line number	Diff line number	Diff line
		@@ -24,6 +24,7 @@
		#include <signal.h>
		#include <stdio.h>
		#include <stdlib.h>
		#include <sys/capability.h>
		#include <sys/prctl.h>

		#include <memory>
		@@ -50,13 +51,13 @@

		static const char* root_seclabel = nullptr;

		static void drop_capabilities_bounding_set_if_needed(struct minijail *j) {
		static bool should_drop_capabilities_bounding_set() {
		#if defined(ALLOW_ADBD_ROOT)
		if (__android_log_is_debuggable()) {
		return;
		return false;
		}
		#endif
		minijail_capbset_drop(j, CAP_TO_MASK(CAP_SETUID) \| CAP_TO_MASK(CAP_SETGID));
		return true;
		}

		static bool should_drop_privileges() {
		@@ -117,13 +118,37 @@ static void drop_privileges(int server_port) {
		// Don't listen on a port (default 5037) if running in secure mode.
		// Don't run as root if running in secure mode.
		if (should_drop_privileges()) {
		drop_capabilities_bounding_set_if_needed(jail.get());
		const bool should_drop_caps = should_drop_capabilities_bounding_set();

		if (should_drop_caps) {
		minijail_use_caps(jail.get(), CAP_TO_MASK(CAP_SETUID) \| CAP_TO_MASK(CAP_SETGID));
		}

		minijail_change_gid(jail.get(), AID_SHELL);
		minijail_change_uid(jail.get(), AID_SHELL);
		// minijail_enter() will abort if any priv-dropping step fails.
		minijail_enter(jail.get());

		// Whenever ambient capabilities are being used, minijail cannot
		// simultaneously drop the bounding capability set to just
		// CAP_SETUID\|CAP_SETGID while clearing the inheritable, effective,
		// and permitted sets. So we need to do that in two steps.
		using ScopedCaps =
		std::unique_ptr<std::remove_pointer<cap_t>::type, std::function<void(cap_t)>>;
		ScopedCaps caps(cap_get_proc(), &cap_free);
		if (cap_clear_flag(caps.get(), CAP_INHERITABLE) == -1) {
		PLOG(FATAL) << "cap_clear_flag(INHERITABLE) failed";
		}
		if (cap_clear_flag(caps.get(), CAP_EFFECTIVE) == -1) {
		PLOG(FATAL) << "cap_clear_flag(PEMITTED) failed";
		}
		if (cap_clear_flag(caps.get(), CAP_PERMITTED) == -1) {
		PLOG(FATAL) << "cap_clear_flag(PEMITTED) failed";
		}
		if (cap_set_proc(caps.get()) != 0) {
		PLOG(FATAL) << "cap_set_proc() failed";
		}

		D("Local port disabled");
		} else {
		// minijail_enter() will abort if any priv-dropping step fails.