From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 070FCC433B4 for ; Thu, 1 Apr 2021 22:00:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B0D89610F9 for ; Thu, 1 Apr 2021 22:00:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234502AbhDAWAz (ORCPT ); Thu, 1 Apr 2021 18:00:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58434 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234474AbhDAWAz (ORCPT ); Thu, 1 Apr 2021 18:00:55 -0400 Received: from mail-io1-xd32.google.com (mail-io1-xd32.google.com [IPv6:2607:f8b0:4864:20::d32]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 70063C0613E6; Thu, 1 Apr 2021 15:00:55 -0700 (PDT) Received: by mail-io1-xd32.google.com with SMTP id f19so3673205ion.3; Thu, 01 Apr 2021 15:00:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:from:to:cc:date:message-id:in-reply-to:references :user-agent:mime-version:content-transfer-encoding; bh=/Y/2bXS+x40LAJhUqAWVL3NSg8OiZMwGupWZBWnd+7I=; b=GpleghdkTh4XLq+t3y0to8GLnIEIpRu43mJRtHF3aZlmc9Fsmu3Akx8T2+1KuT1aJd zHGbLYqSusLyjPW7PZQP1cjyxWPNWOJMVjZvRl+R8hz0jANU9Vpxmn73DXOWW1ghbQ9k ZrmUPvF2UMGMaxcTnl8pECkkD7Y9tLH1tRH+yUaeex+YnZAQ5kGQJBh6TSwC+2NaAPwU 3TbsxdmYtt0XNso4G+8Rtc7hi3hhaEqISpm3iicQFU8gRECmlDEeoRky2GyWHkjtg515 2MROs3S1iq5FMpiVP8LbDavEmKfbwFFAQkBcxripIlJLAgkvwK2DWXCK9AE8qIOtDirk 7n6w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:from:to:cc:date:message-id:in-reply-to :references:user-agent:mime-version:content-transfer-encoding; bh=/Y/2bXS+x40LAJhUqAWVL3NSg8OiZMwGupWZBWnd+7I=; b=Y+NtlNq+DXurR3FlqCXoyb1vDNiAVZlonO3uaGsgtWFDtZSytHr+bEVWppEVi1eYgn 9NU9Qx/Cr5CxC75sAl/yGhXEwAaIHUdtZJAgaY9KRZPPag2vwH5TgkhXnKsmfc8EoFr8 4lQhO9rqiwoT7BBcfem/IOdiFluDnVclLGZaLwOTzxvljWLuKkGH5bSsw9xfYUtyC5cO Eb6NYsKRSFB5PkWm9YkL1kV02RoX9K6WKxTo7B80M3BmfFOrzRtWtdtnCI1wP/npbWyG V9UH19Qdmga31dNY4bUw5nDDkkQrT1vzcZqR1uuJlwEvUZWHpLALpnhQt2KMfYjUia7H 0P3w== X-Gm-Message-State: AOAM531hLAKYf3BaXj7+yiPw+SuPH/8R740xgt80uAV733B4iV3wUnhK eDnuwEHAHwHpdhfW+bIXuF0= X-Google-Smtp-Source: ABdhPJzpkdM7I4dBfiaSeNQnnZj+zjtjzQXobO2w+vNethUwToag5imhLOvPR4eXSFFbWExa+bePyA== X-Received: by 2002:a5d:960d:: with SMTP id w13mr8108720iol.126.1617314454840; Thu, 01 Apr 2021 15:00:54 -0700 (PDT) Received: from [127.0.1.1] ([172.242.244.146]) by smtp.gmail.com with ESMTPSA id q207sm3420052iod.6.2021.04.01.15.00.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 01 Apr 2021 15:00:54 -0700 (PDT) Subject: [PATCH bpf v2 2/2] bpf, sockmap: fix incorrect fwd_alloc accounting From: John Fastabend To: xiyou.wangcong@gmail.com, andrii.nakryiko@gmail.com, daniel@iogearbox.net, ast@fb.com Cc: john.fastabend@gmail.com, bpf@vger.kernel.org, netdev@vger.kernel.org, lmb@cloudflare.com Date: Thu, 01 Apr 2021 15:00:40 -0700 Message-ID: <161731444013.68884.4021114312848535993.stgit@john-XPS-13-9370> In-Reply-To: <161731427139.68884.1934993103507544474.stgit@john-XPS-13-9370> References: <161731427139.68884.1934993103507544474.stgit@john-XPS-13-9370> User-Agent: StGit/0.23-85-g6af9 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Incorrect accounting fwd_alloc can result in a warning when the socket is torn down, [18455.319240] WARNING: CPU: 0 PID: 24075 at net/core/stream.c:208 sk_stream_kill_queues+0x21f/0x230 [...] [18455.319543] Call Trace: [18455.319556] inet_csk_destroy_sock+0xba/0x1f0 [18455.319577] tcp_rcv_state_process+0x1b4e/0x2380 [18455.319593] ? lock_downgrade+0x3a0/0x3a0 [18455.319617] ? tcp_finish_connect+0x1e0/0x1e0 [18455.319631] ? sk_reset_timer+0x15/0x70 [18455.319646] ? tcp_schedule_loss_probe+0x1b2/0x240 [18455.319663] ? lock_release+0xb2/0x3f0 [18455.319676] ? __release_sock+0x8a/0x1b0 [18455.319690] ? lock_downgrade+0x3a0/0x3a0 [18455.319704] ? lock_release+0x3f0/0x3f0 [18455.319717] ? __tcp_close+0x2c6/0x790 [18455.319736] ? tcp_v4_do_rcv+0x168/0x370 [18455.319750] tcp_v4_do_rcv+0x168/0x370 [18455.319767] __release_sock+0xbc/0x1b0 [18455.319785] __tcp_close+0x2ee/0x790 [18455.319805] tcp_close+0x20/0x80 This currently happens because on redirect case we do skb_set_owner_r() with the original sock. This increments the fwd_alloc memory accounting on the original sock. Then on redirect we may push this into the queue of the psock we are redirecting to. When the skb is flushed from the queue we give the memory back to the original sock. The problem is if the original sock is destroyed/closed with skbs on another psocks queue then the original sock will not have a way to reclaim the memory before being destroyed. Then above warning will be thrown sockA sockB sk_psock_strp_read() sk_psock_verdict_apply() -- SK_REDIRECT -- sk_psock_skb_redirect() skb_queue_tail(psock_other->ingress_skb..) sk_close() sock_map_unref() sk_psock_put() sk_psock_drop() sk_psock_zap_ingress() At this point we have torn down our own psock, but have the outstanding skb in psock_other. Note that SK_PASS doesn't have this problem because the sk_psock_drop() logic releases the skb, its still associated with our psock. To resolve lets only account for sockets on the ingress queue that are still associated with the current socket. On the redirect case we will check memory limits per 6fa9201a89898, but will omit fwd_alloc accounting until skb is actually enqueued. When the skb is sent via skb_send_sock_locked or received with sk_psock_skb_ingress memory will be claimed on psock_other. Reported-by: Andrii Nakryiko Fixes: 6fa9201a89898 ("bpf, sockmap: Avoid returning unneeded EAGAIN when redirecting to self") Signed-off-by: John Fastabend --- net/core/skmsg.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/net/core/skmsg.c b/net/core/skmsg.c index 1261512d6807..5def3a2e85be 100644 --- a/net/core/skmsg.c +++ b/net/core/skmsg.c @@ -488,6 +488,7 @@ static int sk_psock_skb_ingress_self(struct sk_psock *psock, struct sk_buff *skb if (unlikely(!msg)) return -EAGAIN; sk_msg_init(msg); + skb_set_owner_r(skb, sk); return sk_psock_skb_ingress_enqueue(skb, psock, sk, msg); } @@ -790,7 +791,6 @@ static void sk_psock_tls_verdict_apply(struct sk_buff *skb, struct sock *sk, int { switch (verdict) { case __SK_REDIRECT: - skb_set_owner_r(skb, sk); sk_psock_skb_redirect(skb); break; case __SK_PASS: @@ -808,10 +808,6 @@ int sk_psock_tls_strp_read(struct sk_psock *psock, struct sk_buff *skb) rcu_read_lock(); prog = READ_ONCE(psock->progs.skb_verdict); if (likely(prog)) { - /* We skip full set_owner_r here because if we do a SK_PASS - * or SK_DROP we can skip skb memory accounting and use the - * TLS context. - */ skb->sk = psock->sk; tcp_skb_bpf_redirect_clear(skb); ret = sk_psock_bpf_run(psock, prog, skb); @@ -880,12 +876,13 @@ static void sk_psock_strp_read(struct strparser *strp, struct sk_buff *skb) kfree_skb(skb); goto out; } - skb_set_owner_r(skb, sk); prog = READ_ONCE(psock->progs.skb_verdict); if (likely(prog)) { + skb->sk = sk; tcp_skb_bpf_redirect_clear(skb); ret = sk_psock_bpf_run(psock, prog, skb); ret = sk_psock_map_verd(ret, tcp_skb_bpf_redirect_fetch(skb)); + skb->sk = NULL; } sk_psock_verdict_apply(psock, skb, ret); out: @@ -956,12 +953,13 @@ static int sk_psock_verdict_recv(read_descriptor_t *desc, struct sk_buff *skb, kfree_skb(skb); goto out; } - skb_set_owner_r(skb, sk); prog = READ_ONCE(psock->progs.skb_verdict); if (likely(prog)) { + skb->sk = sk; tcp_skb_bpf_redirect_clear(skb); ret = sk_psock_bpf_run(psock, prog, skb); ret = sk_psock_map_verd(ret, tcp_skb_bpf_redirect_fetch(skb)); + skb->sk = NULL; } sk_psock_verdict_apply(psock, skb, ret); out: