bpf: pass sk to helper functions
BPF helper functions access socket fields through skb->sk. This is not set in ingress cgroup and socket filters. The association is only made in skb_set_owner_r once the filter has accepted the packet. Sk is available as socket lookup has taken place. Temporarily set skb->sk to sk in these cases. Signed-off-by: Willem de Bruijn <willemb@google.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -154,7 +154,7 @@ int __cgroup_bpf_update(struct cgroup *cgrp, struct cgroup *parent,
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/**
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* __cgroup_bpf_run_filter_skb() - Run a program for packet filtering
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* @sk: The socken sending or receiving traffic
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* @sk: The socket sending or receiving traffic
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* @skb: The skb that is being sent or received
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* @type: The type of program to be exectuted
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*
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@ -189,10 +189,13 @@ int __cgroup_bpf_run_filter_skb(struct sock *sk,
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prog = rcu_dereference(cgrp->bpf.effective[type]);
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if (prog) {
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unsigned int offset = skb->data - skb_network_header(skb);
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struct sock *save_sk = skb->sk;
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skb->sk = sk;
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__skb_push(skb, offset);
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ret = bpf_prog_run_save_cb(prog, skb) == 1 ? 0 : -EPERM;
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__skb_pull(skb, offset);
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skb->sk = save_sk;
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}
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rcu_read_unlock();
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@ -92,8 +92,13 @@ int sk_filter_trim_cap(struct sock *sk, struct sk_buff *skb, unsigned int cap)
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rcu_read_lock();
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filter = rcu_dereference(sk->sk_filter);
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if (filter) {
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unsigned int pkt_len = bpf_prog_run_save_cb(filter->prog, skb);
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struct sock *save_sk = skb->sk;
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unsigned int pkt_len;
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skb->sk = sk;
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pkt_len = bpf_prog_run_save_cb(filter->prog, skb);
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err = pkt_len ? pskb_trim(skb, max(cap, pkt_len)) : -EPERM;
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skb->sk = save_sk;
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}
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rcu_read_unlock();
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