From patchwork Mon Mar 27 17:54:41 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Fastabend X-Patchwork-Id: 13189781 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B0BB9C76195 for ; Mon, 27 Mar 2023 17:55:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232453AbjC0RzP (ORCPT ); Mon, 27 Mar 2023 13:55:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33882 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232475AbjC0RzE (ORCPT ); Mon, 27 Mar 2023 13:55:04 -0400 Received: from mail-pl1-x62f.google.com (mail-pl1-x62f.google.com [IPv6:2607:f8b0:4864:20::62f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DEC3640C8; Mon, 27 Mar 2023 10:55:01 -0700 (PDT) Received: by mail-pl1-x62f.google.com with SMTP id k2so9174812pll.8; Mon, 27 Mar 2023 10:55:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; t=1679939701; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=/vwLJbRVFroNWnth4Z1LSY+PY6/N1S6I5xUuSkt0za4=; b=jKmPHdNaQmwP6xZRzr98n8oRKxgSJ6auAgwKK2TjuROOdIuiBy1jLhhZOfVAZVmID0 XGqp1kyNHCv9W5NpdC95eCmPOhdBJywLsmRKSWQpcG1dpuekGrHAQEZdSxe/lG6DRRfa uEdp7sdKSFdWb/FU81XoIdPX+xnhy17Tb0vC25yFC4vCgqmcDcizEkVh82V/C2hmF5Ag 8cq1jv97MYZRJdmxYdsiiJ7vCG29cjuzHUU6w8F+VYwKYH7U0EsiKx9y2cKkgNxehoRP 28Wz+W/WUnJDWutgTsNCQpk/2hQk3dcyXLOlgmm6MqhoscfPGaflwrpno3ycO9LeZeMb w5fQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1679939701; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=/vwLJbRVFroNWnth4Z1LSY+PY6/N1S6I5xUuSkt0za4=; b=x7POzhoKQZ1a00UgOVdIGgL5iZpaVrl7CfnbL4wQ6sig9AI2elka3Va67HUZ9HAdlj xfHHmXKLEaNL+sl8f7x7AryDqtR+IMfotztMYSqAtj3ZIh+A91Ek84tQBa82lqFgXKZD FxpIFxJz5Nfv39de/eZSnVDDVWQv7F56AXGAxH55t63J3nS+8hZCESHCRhA7bRkV++rO Sa8qdG6OyIsSF+KfvT2K93GdxazttO1pzalAz9EScuzYx3LHGr0OnqNAF5kj7iHgtqXG 3Yerc366SvQZpnCjo+TTgpXT6pbxGzpiyvYyxhhGbozKua8/rg/IJtj2m4MQP6NgQflf Cnxw== X-Gm-Message-State: AO0yUKXkDsSqfeNmVs+FYjxk1fnksVlVocnZb7SHvXkCeWbmTgZHHWVi Xy86JTRJIGhZXjpG9KpP4Yg= X-Google-Smtp-Source: AK7set/CpyuVV07v8eFOHV0PdkZRtg15OXPaRsiqAH0oHxiPAGpx8M4ZHfjAEpep6PqEPh+6i0tuwQ== X-Received: by 2002:a05:6a20:c10f:b0:d9:84d2:7a9f with SMTP id bh15-20020a056a20c10f00b000d984d27a9fmr11615054pzb.24.1679939701295; Mon, 27 Mar 2023 10:55:01 -0700 (PDT) Received: from john.lan ([98.97.117.131]) by smtp.gmail.com with ESMTPSA id r1-20020a62e401000000b005a8ba70315bsm19408316pfh.6.2023.03.27.10.54.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Mar 2023 10:55:00 -0700 (PDT) From: John Fastabend To: cong.wang@bytedance.com, jakub@cloudflare.com, daniel@iogearbox.net, lmb@isovalent.com, edumazet@google.com Cc: john.fastabend@gmail.com, bpf@vger.kernel.org, netdev@vger.kernel.org, ast@kernel.org, andrii@kernel.org, will@isovalent.com Subject: [PATCH bpf v2 07/12] bpf: sockmap incorrectly handling copied_seq Date: Mon, 27 Mar 2023 10:54:41 -0700 Message-Id: <20230327175446.98151-8-john.fastabend@gmail.com> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20230327175446.98151-1-john.fastabend@gmail.com> References: <20230327175446.98151-1-john.fastabend@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net The read_skb() logic is incrementing the tcp->copied_seq which is used for among other things calculating how many outstanding bytes can be read by the application. This results in application errors, if the application does an ioctl(FIONREAD) we return zero because this is calculated from the copied_seq value. To fix this we move tcp->copied_seq accounting into the recv handler so that we update these when the recvmsg() hook is called and data is in fact copied into user buffers. This gives an accurate FIONREAD value as expected and improves ACK handling. Before we were calling the tcp_rcv_space_adjust() which would update 'number of bytes copied to user in last RTT' which is wrong for programs returning SK_PASS. The bytes are only copied to the user when recvmsg is handled. Doing the fix for recvmsg is straightforward, but fixing redirect and SK_DROP pkts is a bit tricker. Build a tcp_psock_eat() helper and then call this from skmsg handlers. This fixes another issue where a broken socket with a BPF program doing a resubmit could hang the receiver. This happened because although read_skb() consumed the skb through sock_drop() it did not update the copied_seq. Now if a single reccv socket is redirecting to many sockets (for example for lb) the receiver sk will be hung even though we might expect it to continue. The hang comes from not updating the copied_seq numbers and memory pressure resulting from that. We have a slight layer problem of calling tcp_eat_skb even if its not a TCP socket. To fix we could refactor and create per type receiver handlers. I decided this is more work than we want in the fix and we already have some small tweaks depending on caller that use the helper skb_bpf_strparser(). So we extend that a bit and always set the strparser bit when it is in use and then we can gate the seq_copied updates on this. Fixes: 04919bed948dc ("tcp: Introduce tcp_read_skb()") Signed-off-by: John Fastabend --- include/net/tcp.h | 3 +++ net/core/skmsg.c | 7 +++++-- net/ipv4/tcp.c | 10 +--------- net/ipv4/tcp_bpf.c | 28 +++++++++++++++++++++++++++- 4 files changed, 36 insertions(+), 12 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index db9f828e9d1e..674044b8bdaf 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1467,6 +1467,8 @@ static inline void tcp_adjust_rcv_ssthresh(struct sock *sk) } void tcp_cleanup_rbuf(struct sock *sk, int copied); +void __tcp_cleanup_rbuf(struct sock *sk, int copied); + /* We provision sk_rcvbuf around 200% of sk_rcvlowat. * If 87.5 % (7/8) of the space has been consumed, we want to override @@ -2321,6 +2323,7 @@ struct sk_psock; struct proto *tcp_bpf_get_proto(struct sock *sk, struct sk_psock *psock); int tcp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore); void tcp_bpf_clone(const struct sock *sk, struct sock *newsk); +void tcp_eat_skb(struct sock *sk, struct sk_buff *skb); #endif /* CONFIG_BPF_SYSCALL */ int tcp_bpf_sendmsg_redir(struct sock *sk, bool ingress, diff --git a/net/core/skmsg.c b/net/core/skmsg.c index 10e5481da662..b141b422697c 100644 --- a/net/core/skmsg.c +++ b/net/core/skmsg.c @@ -1051,11 +1051,14 @@ static int sk_psock_verdict_apply(struct sk_psock *psock, struct sk_buff *skb, mutex_unlock(&psock->work_mutex); break; case __SK_REDIRECT: + tcp_eat_skb(psock->sk, skb); err = sk_psock_skb_redirect(psock, skb); break; case __SK_DROP: default: out_free: + tcp_eat_skb(psock->sk, skb); + skb_bpf_redirect_clear(skb); sock_drop(psock->sk, skb); } @@ -1100,8 +1103,7 @@ static void sk_psock_strp_read(struct strparser *strp, struct sk_buff *skb) skb_dst_drop(skb); skb_bpf_redirect_clear(skb); ret = bpf_prog_run_pin_on_cpu(prog, skb); - if (ret == SK_PASS) - skb_bpf_set_strparser(skb); + skb_bpf_set_strparser(skb); ret = sk_psock_map_verd(ret, skb_bpf_redirect_fetch(skb)); skb->sk = NULL; } @@ -1207,6 +1209,7 @@ static int sk_psock_verdict_recv(struct sock *sk, struct sk_buff *skb) psock = sk_psock(sk); if (unlikely(!psock)) { len = 0; + tcp_eat_skb(sk, skb); sock_drop(sk, skb); goto out; } diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 6572962b0237..e2594d8e3429 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1568,7 +1568,7 @@ static int tcp_peek_sndq(struct sock *sk, struct msghdr *msg, int len) * calculation of whether or not we must ACK for the sake of * a window update. */ -static void __tcp_cleanup_rbuf(struct sock *sk, int copied) +void __tcp_cleanup_rbuf(struct sock *sk, int copied) { struct tcp_sock *tp = tcp_sk(sk); bool time_to_ack = false; @@ -1783,14 +1783,6 @@ int tcp_read_skb(struct sock *sk, skb_read_actor_t recv_actor) break; } } - WRITE_ONCE(tp->copied_seq, seq); - - tcp_rcv_space_adjust(sk); - - /* Clean up data we have read: This will do ACK frames. */ - if (copied > 0) - __tcp_cleanup_rbuf(sk, copied); - return copied; } EXPORT_SYMBOL(tcp_read_skb); diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c index 2c75bbcbefed..6fb9978d72e3 100644 --- a/net/ipv4/tcp_bpf.c +++ b/net/ipv4/tcp_bpf.c @@ -11,6 +11,24 @@ #include #include +void tcp_eat_skb(struct sock *sk, struct sk_buff *skb) +{ + struct tcp_sock *tcp; + int copied; + + if (!skb || !skb->len || !sk_is_tcp(sk)) + return; + + if (skb_bpf_strparser(skb)) + return; + + tcp = tcp_sk(sk); + copied = tcp->copied_seq + skb->len; + WRITE_ONCE(tcp->copied_seq, copied); + tcp_rcv_space_adjust(sk); + __tcp_cleanup_rbuf(sk, skb->len); +} + static int bpf_tcp_ingress(struct sock *sk, struct sk_psock *psock, struct sk_msg *msg, u32 apply_bytes, int flags) { @@ -198,8 +216,10 @@ static int tcp_bpf_recvmsg_parser(struct sock *sk, int flags, int *addr_len) { + struct tcp_sock *tcp = tcp_sk(sk); + u32 seq = tcp->copied_seq; struct sk_psock *psock; - int copied; + int copied = 0; if (unlikely(flags & MSG_ERRQUEUE)) return inet_recv_error(sk, msg, len, addr_len); @@ -241,9 +261,11 @@ static int tcp_bpf_recvmsg_parser(struct sock *sk, if (is_fin) { copied = 0; + seq++; goto out; } } + seq += copied; if (!copied) { long timeo; int data; @@ -281,6 +303,10 @@ static int tcp_bpf_recvmsg_parser(struct sock *sk, copied = -EAGAIN; } out: + WRITE_ONCE(tcp->copied_seq, seq); + tcp_rcv_space_adjust(sk); + if (copied > 0) + __tcp_cleanup_rbuf(sk, copied); release_sock(sk); sk_psock_put(sk, psock); return copied;