grsecurity RBAC system

A few notes I wrote down about enabling the (very intense) grsecuriy RBAC system on micro.

  1. If you have role_allow_ip defined and you try and “do something” from an IP not in that allowed list – you’ll end up in the default role.  That can be hard to figure out at first, you know you have a role setup for the user, but you’re not ending up in it.  That’s why.
  2. A subject in a less specific policy with an “i” will override a more specific subject.i.e.This “/” subject:subject / o {    /bin        rxi}will win over this:subject /bin/bash o {}/bin/bash will use the polices from the first subject, not the second.
  3. To be able to unlink (delete!) a file, you need both d and the w subject flags.  d alone isn’t enough.
  4. Be VERY careful with the C subject flag.  It will kill everything with the same IP address, silently.  Your MYSQL server might be dead and you won’t know it.
  5. Shared Libraries (.so) need the rx flag, x alone isn’t enough.
    subject /bin/bash {    

    /lib            rx
  6. The -V flag to gradm -E will give some useful information!

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