On Jan 30, 2025, at 12:23 PM, Alexei Starovoitov [off-list ref] wrote:

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For all these reasons I don't like this approach.
This "generality" doesn't make it cleaner or easier to extend.
For the patch 6... just repeat what specialize_kfunc()
currently does for dynptr ?

Yes, specialize_kfunc() can handle this. But we will need to use
d_inode_locked_hooks from 6/7 in specialize_kfunc(). It works,
but it is not clean (to me).

I'm missing why that would be necessary to cross the layers
so much. I guess the code will tell.
Pls send an rfc to illustrate the unclean part.

The actual code is actually a lot cleaner than I thought. We just
need to use the bpf_lsm_has_d_inode_locked() helper in verifier.c. 

Thanks,
Song

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I will revise this set so that the polymorphism logic in handled
in specialize_kfunc(). For longer term, maybe we should discuss
"move some logic from verifier core to kfuncs" in the upcoming
LSF/MM/BPF?

imo such topic is too narrow and detail oriented.
There is not much to gain from discussing it at lsfmm.
email works well for such discussions.