Restrict use of POSIX message queues

[gnoack]

Should we restrict the use of POSIX message queues?

https://man7.org/linux/man-pages/man7/mq_overview.7.html

According to mq_open(3), this is implemented based on a system call with the same name, but I could not find existing references to it in the other LSMs. (I wonder whether this is getting restricted in a different way?)

[l0kod]

Should we restrict the use of POSIX message queues?

Yes!

According to mq_open(3), this is implemented based on a system call with the same name, but I could not find existing references to it in the other LSMs. (I wonder whether this is getting restricted in a different way?)

There is at least a call to security_ionde_permission() from prepare_open(). There are also security_msg_queue_*() hooks.

Related to #7, #8, and #30.