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bpf: Don't refcount LISTEN sockets in sk_assign()

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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
This commit is contained in:
Joe Stringer
2020-03-29 15:53:40 -07:00
committed by Alexei Starovoitov
parent 71489e21d7
commit 7ae215d23c
3 changed files with 22 additions and 12 deletions
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6
net/core/filter.c
View File

@@ -5401,8 +5401,7 @@ static const struct bpf_func_proto bpf_sk_lookup_udp_proto = {
BPF_CALL_1(bpf_sk_release, struct sock *, sk)
{
/* Only full sockets have sk->sk_flags. */
if (!sk_fullsock(sk) || !sock_flag(sk, SOCK_RCU_FREE))
if (sk_is_refcounted(sk))
sock_gen_put(sk);
return 0;
}
@@ -5928,7 +5927,8 @@ BPF_CALL_3(bpf_sk_assign, struct sk_buff *, skb, struct sock *, sk, u64, flags)
return -ENETUNREACH;
if (unlikely(sk->sk_reuseport))
return -ESOCKTNOSUPPORT;
if (unlikely(!refcount_inc_not_zero(&sk->sk_refcnt)))
if (sk_is_refcounted(sk) &&
unlikely(!refcount_inc_not_zero(&sk->sk_refcnt)))
return -ENOENT;
skb_orphan(skb);

3
net/core/sock.c
View File

@@ -2077,7 +2077,8 @@ EXPORT_SYMBOL(sock_efree);
#ifdef CONFIG_INET
void sock_pfree(struct sk_buff *skb)
{
sock_gen_put(skb->sk);
if (sk_is_refcounted(skb->sk))
sock_gen_put(skb->sk);
}
EXPORT_SYMBOL(sock_pfree);
#endif /* CONFIG_INET */