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[73.93.5.123]) by smtp.gmail.com with ESMTPSA id i187sm8710386pfg.33.2020.03.29.15.53.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 29 Mar 2020 15:53:51 -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: [PATCHv5 bpf-next 3/5] bpf: Don't refcount LISTEN sockets in sk_assign() Date: Sun, 29 Mar 2020 15:53:40 -0700 Message-Id: <20200329225342.16317-4-joe@wand.net.nz> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200329225342.16317-1-joe@wand.net.nz> References: <20200329225342.16317-1-joe@wand.net.nz> MIME-Version: 1.0 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 Acked-by: Martin KaFai Lau --- 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 */