tree 89894078716e334e420ecf2ba0c734faaa0cf68a
parent e39455b5316103f8de7f7e1e51dfa08a544e52b0
author Luis Hector Chavez <lhchavez@google.com> 1475016955 -0700
committer ChromeOS Commit Bot <chromeos-commit-bot@chromium.org> 1475603959 +0000

login: Explicitly remount the container with MS_RDONLY

Turns out that even if the filesystem is mounted read-only outside the
container, the same mount inside the container will preserve the flag
that was passed explicitly (0, meaning read-write), even if the
underlying filesystem was marked read-only.

This change explicitly remounts the containers' rootfs with MS_RDONLY if
the underlying filesystem is mounted read-only.

BUG=b:31771616
TEST=FEATURES="test" emerge-${BOARD} chromeos-base/chromeos-login
TEST=test_that cheets_FileSystemPermission  # passes
TEST=test_that cheets_FileSystemPermission  # fails with WRITABLE_MOUNT=1

Change-Id: I1d715c22779226937546e0566dceb0de29501b60
Reviewed-on: https://chromium-review.googlesource.com/390412
Commit-Ready: Luis Hector Chavez <lhchavez@google.com>
Tested-by: Luis Hector Chavez <lhchavez@google.com>
Reviewed-by: Luis Hector Chavez <lhchavez@google.com>
(cherry picked from commit debfbb561c97861f211c877d9de233bd67d5a313)
Reviewed-on: https://chromium-review.googlesource.com/392348
Trybot-Ready: Luis Hector Chavez <lhchavez@google.com>
Reviewed-by: Dan Erat <derat@chromium.org>
Commit-Queue: Luis Hector Chavez <lhchavez@google.com>