journald: fix dangling /dev/log symlink

With the move to journald, the syslog socket at /dev/log has been
replaced by a symlink pointing to /run/systemd/journal/dev-log. Certain
processes using minijail bind mount /dev, but don't bind mount the
symlink target, and so have a dangling symlink at /dev/log. Most
processes using minijail use --mount-dev and mount /dev/log explicitly
and so aren't affected by this. Mount /run/systemd/journal/ into the
namespaces of processes that directly mount /dev.

BUG=chromium:932761
TEST=Ensure log messages from affected processes can be seen in the
journal
TEST=Inspect the mount namespaces of all processes running on the system
for any dangling symlinks at /dev/log

Change-Id: I577e71540d8b78aad9672cc66f6825873689616d
Reviewed-on: https://chromium-review.googlesource.com/1478386
Commit-Ready: Christopher Morin <cmtm@google.com>
Tested-by: Christopher Morin <cmtm@google.com>
Reviewed-by: Dylan Reid <dgreid@chromium.org>
1 file changed