[minijail] pid namespace implies vfs namespace

Make a pid namespace imply both a new vfs namespace and a /proc remount, since
if we don't remount /proc, the old pid namespace is still reachable through the
old mount there.

BUG=chromium-os:25303
TEST=security_Minijail0

Change-Id: I91887d3ed6bc0e958e249c3c158735bc04f20fcd
Signed-off-by: Elly Jones <ellyjones@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/14617
Reviewed-by: Kees Cook <keescook@chromium.org>
4 files changed