From: Joe Stringer <joe@wand.net.nz>
To: bpf@vger.kernel.org
Cc: netdev@vger.kernel.org, daniel@iogearbox.net, ast@kernel.org,
eric.dumazet@gmail.com, lmb@cloudflare.com, kafai@fb.com
Subject: [PATCHv5 bpf-next 3/5] bpf: Don't refcount LISTEN sockets in sk_assign()
Date: Sun, 29 Mar 2020 15:53:40 -0700 [thread overview]
Message-ID: <20200329225342.16317-4-joe@wand.net.nz> (raw)
In-Reply-To: <20200329225342.16317-1-joe@wand.net.nz>
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>
Acked-by: Martin KaFai Lau <kafai@fb.com>
---
v5: Guard sock_gen_put() with #ifdef for CONFIG_INET
v4: Directly use sock_gen_put() from sock_pfree()
Acked
v3: No changes
v2: Initial version
---
include/net/sock.h | 25 +++++++++++++++++--------
net/core/filter.c | 6 +++---
net/core/sock.c | 3 ++-
3 files changed, 22 insertions(+), 12 deletions(-)
diff --git a/include/net/sock.h b/include/net/sock.h
index f81d528845f6..6d84784d33fa 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -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.
diff --git a/net/core/filter.c b/net/core/filter.c
index ac5c1633f8d2..7628b947dbc3 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -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);
diff --git a/net/core/sock.c b/net/core/sock.c
index 87e3a03c9056..da32d9b6d09f 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -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 */
--
2.20.1
next prev parent reply other threads:[~2020-03-29 22:53 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-29 22:53 [PATCHv5 bpf-next 0/5] Add bpf_sk_assign eBPF helper Joe Stringer
2020-03-29 22:53 ` [PATCHv5 bpf-next 1/5] bpf: Add socket assign support Joe Stringer
2020-03-29 22:53 ` [PATCHv5 bpf-next 2/5] net: Track socket refcounts in skb_steal_sock() Joe Stringer
2020-03-29 22:53 ` Joe Stringer [this message]
2020-03-29 22:53 ` [PATCHv5 bpf-next 4/5] selftests: bpf: add test for sk_assign Joe Stringer
2020-04-01 23:19 ` Andrii Nakryiko
[not found] ` <CAOftzPj5aKspwmZ72t+ivjE72CUWObfgekpiQM+iCTya5hxgGw@mail.gmail.com>
2020-04-03 20:50 ` Andrii Nakryiko
2020-03-29 22:53 ` [PATCHv5 bpf-next 5/5] selftests: bpf: Extend sk_assign tests for UDP Joe Stringer
2020-03-30 20:46 ` [PATCHv5 bpf-next 0/5] Add bpf_sk_assign eBPF helper Alexei Starovoitov
2020-03-30 22:00 ` Joe Stringer
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