bpf: Don't refcount LISTEN sockets in sk_assign()
Avoid taking a reference on listen sockets by checking the socket type in the sk_assign and in the corresponding skb_steal_sock() code in the the transport layer, and by ensuring that the prefetch free (sock_pfree) function uses the same logic to check whether the socket is refcounted. Suggested-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Joe Stringer <joe@wand.net.nz> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20200329225342.16317-4-joe@wand.net.nz
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@ -2537,6 +2537,21 @@ skb_sk_is_prefetched(struct sk_buff *skb)
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#endif /* CONFIG_INET */
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}
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/* This helper checks if a socket is a full socket,
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* ie _not_ a timewait or request socket.
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*/
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static inline bool sk_fullsock(const struct sock *sk)
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{
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return (1 << sk->sk_state) & ~(TCPF_TIME_WAIT | TCPF_NEW_SYN_RECV);
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}
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static inline bool
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sk_is_refcounted(struct sock *sk)
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{
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/* Only full sockets have sk->sk_flags. */
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return !sk_fullsock(sk) || !sock_flag(sk, SOCK_RCU_FREE);
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}
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/**
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* skb_steal_sock
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* @skb to steal the socket from
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@ -2549,6 +2564,8 @@ skb_steal_sock(struct sk_buff *skb, bool *refcounted)
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struct sock *sk = skb->sk;
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*refcounted = true;
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if (skb_sk_is_prefetched(skb))
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*refcounted = sk_is_refcounted(sk);
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skb->destructor = NULL;
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skb->sk = NULL;
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return sk;
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@ -2557,14 +2574,6 @@ skb_steal_sock(struct sk_buff *skb, bool *refcounted)
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return NULL;
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}
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/* This helper checks if a socket is a full socket,
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* ie _not_ a timewait or request socket.
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*/
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static inline bool sk_fullsock(const struct sock *sk)
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{
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return (1 << sk->sk_state) & ~(TCPF_TIME_WAIT | TCPF_NEW_SYN_RECV);
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}
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/* Checks if this SKB belongs to an HW offloaded socket
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* and whether any SW fallbacks are required based on dev.
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* Check decrypted mark in case skb_orphan() cleared socket.
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@ -5401,8 +5401,7 @@ static const struct bpf_func_proto bpf_sk_lookup_udp_proto = {
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BPF_CALL_1(bpf_sk_release, struct sock *, sk)
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{
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/* Only full sockets have sk->sk_flags. */
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if (!sk_fullsock(sk) || !sock_flag(sk, SOCK_RCU_FREE))
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if (sk_is_refcounted(sk))
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sock_gen_put(sk);
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return 0;
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}
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@ -5928,7 +5927,8 @@ BPF_CALL_3(bpf_sk_assign, struct sk_buff *, skb, struct sock *, sk, u64, flags)
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return -ENETUNREACH;
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if (unlikely(sk->sk_reuseport))
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return -ESOCKTNOSUPPORT;
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if (unlikely(!refcount_inc_not_zero(&sk->sk_refcnt)))
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if (sk_is_refcounted(sk) &&
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unlikely(!refcount_inc_not_zero(&sk->sk_refcnt)))
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return -ENOENT;
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skb_orphan(skb);
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@ -2077,7 +2077,8 @@ EXPORT_SYMBOL(sock_efree);
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#ifdef CONFIG_INET
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void sock_pfree(struct sk_buff *skb)
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{
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sock_gen_put(skb->sk);
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if (sk_is_refcounted(skb->sk))
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sock_gen_put(skb->sk);
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}
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EXPORT_SYMBOL(sock_pfree);
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#endif /* CONFIG_INET */
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