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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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25
include/net/sock.h
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@@ -2537,6 +2537,21 @@ skb_sk_is_prefetched(struct sk_buff *skb)
#endif /* CONFIG_INET */
}
/* This helper checks if a socket is a full socket,
* ie _not_ a timewait or request socket.
*/
static inline bool sk_fullsock(const struct sock *sk)
{
return (1 << sk->sk_state) & ~(TCPF_TIME_WAIT | TCPF_NEW_SYN_RECV);
}
static inline bool
sk_is_refcounted(struct sock *sk)
{
/* Only full sockets have sk->sk_flags. */
return !sk_fullsock(sk) || !sock_flag(sk, SOCK_RCU_FREE);
}
/**
* skb_steal_sock
* @skb to steal the socket from
@@ -2549,6 +2564,8 @@ skb_steal_sock(struct sk_buff *skb, bool *refcounted)
struct sock *sk = skb->sk;
*refcounted = true;
if (skb_sk_is_prefetched(skb))
*refcounted = sk_is_refcounted(sk);
skb->destructor = NULL;
skb->sk = NULL;
return sk;
@@ -2557,14 +2574,6 @@ skb_steal_sock(struct sk_buff *skb, bool *refcounted)
return NULL;
}
/* This helper checks if a socket is a full socket,
* ie _not_ a timewait or request socket.
*/
static inline bool sk_fullsock(const struct sock *sk)
{
return (1 << sk->sk_state) & ~(TCPF_TIME_WAIT | TCPF_NEW_SYN_RECV);
}
/* Checks if this SKB belongs to an HW offloaded socket
* and whether any SW fallbacks are required based on dev.
* Check decrypted mark in case skb_orphan() cleared socket.