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[73.93.5.123]) by smtp.gmail.com with ESMTPSA id e10sm17605716pfm.121.2020.03.24.22.58.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 24 Mar 2020 22:58:01 -0700 (PDT) From: Joe Stringer 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: [PATCHv2 bpf-next 4/5] bpf: Don't refcount LISTEN sockets in sk_assign() Date: Tue, 24 Mar 2020 22:57:44 -0700 Message-Id: <20200325055745.10710-5-joe@wand.net.nz> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200325055745.10710-1-joe@wand.net.nz> References: <20200325055745.10710-1-joe@wand.net.nz> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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 Signed-off-by: Joe Stringer --- 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 1ca2e808cb8e..3ec1865f173e 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -2533,6 +2533,21 @@ skb_sk_is_prefetched(struct sk_buff *skb) return skb->destructor == sock_pfree; } +/* 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 @@ -2545,6 +2560,8 @@ 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; @@ -2553,14 +2570,6 @@ 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 0fada7fe9b75..997b8606167e 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -5343,8 +5343,7 @@ 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; } @@ -5870,7 +5869,8 @@ BPF_CALL_3(bpf_sk_assign, struct sk_buff *, skb, struct sock *, sk, u64, flags) return -ESOCKTNOSUPPORT; if (unlikely(dev_net(skb->dev) != sock_net(sk))) return -ENETUNREACH; - 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 cfaf60267360..a2ab79446f59 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -2076,7 +2076,8 @@ EXPORT_SYMBOL(sock_efree); */ void sock_pfree(struct sk_buff *skb) { - sock_edemux(skb); + if (sk_is_refcounted(skb->sk)) + sock_edemux(skb); } EXPORT_SYMBOL(sock_pfree); -- 2.20.1