bpf: Allow delete from sockmap/sockhash only if update is allowed

We have seen an influx of syzkaller reports where a BPF program attached to
a tracepoint triggers a locking rule violation by performing a map_delete
on a sockmap/sockhash.

We don't intend to support this artificial use scenario. Extend the
existing verifier allowed-program-type check for updating sockmap/sockhash
to also cover deleting from a map.

From now on only BPF programs which were previously allowed to update
sockmap/sockhash can delete from these map types.

Fixes: ff9105993240 ("bpf, sockmap: Prevent lock inversion deadlock in map delete elem")
Reported-by: Tetsuo Handa <[email protected]>
Reported-by: [email protected]
Signed-off-by: Jakub Sitnicki <[email protected]>
Signed-off-by: Daniel Borkmann <[email protected]>
Tested-by: [email protected]
Acked-by: John Fastabend <[email protected]>
Closes: https://syzkaller.appspot.com/bug?extid=ec941d6e24f633a59172
Link: https://lore.kernel.org/bpf/[email protected]

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