Re: [RFC] struct filename, io_uring and audit troubles

[Al Viro <viro@zeniv.linux.org.uk>]

On Mon, Sep 23, 2024 at 08:11:51PM -0400, Paul Moore wrote:

> >         * get rid of the "repeated getname() on the same address is going to
> > give you the same object" - that can't be relied upon without audit, for one
> > thing and for another... having a syscall that takes two pathnames that gives
> > different audit log (if not predicate evaluation) in cases when those are
> > identical pointers vs. strings with identical contenst is, IMO, somewhat
> > undesirable.  That kills filename->uaddr.
> 
> /uaddr/uptr/ if I'm following you correctly, but yeah, that all seems good.

BTW, what should we do when e.g. mkdir(2) manages to get to the parent, calls
audit_inode() to memorize that one and then gets -ESTALE from nfs_mkdir()?
We repeat the pathwalk, this time with LOOKUP_REVAL (i.e. make sure to ask
the server about each NFS directory we are visiting, even if it had been seen
recently) and arrive to a different directory, which is not stale and where
subdirectory creation succeeds.

The thing is, we call audit_inode(...., AUDIT_INODE_PARENT) twice.  With the
same name, but with different inodes.  Should we log both, or should the
latter call cannibalize the audit_names instance from the earlier?