From patchwork Wed Mar 24 20:59:29 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Fastabend X-Patchwork-Id: 12162367 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 X-Spam-Level: X-Spam-Status: No, score=-12.7 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,URIBL_BLOCKED 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 682F8C433C1 for ; Wed, 24 Mar 2021 21:00:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3C70561A1B for ; Wed, 24 Mar 2021 21:00:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238181AbhCXU7x (ORCPT ); Wed, 24 Mar 2021 16:59:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50346 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238179AbhCXU7o (ORCPT ); Wed, 24 Mar 2021 16:59:44 -0400 Received: from mail-il1-x129.google.com (mail-il1-x129.google.com [IPv6:2607:f8b0:4864:20::129]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D4863C06174A; Wed, 24 Mar 2021 13:59:43 -0700 (PDT) Received: by mail-il1-x129.google.com with SMTP id t6so252771ilp.11; Wed, 24 Mar 2021 13:59:43 -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=wOysoelzRnYOrkG2Z14SpjF49EYeBD1nfmQf5XQ3/pk=; b=D38CFzdvkf2jD2Wj8p9HCX8TUbjmJsfpzJav58tCzaw+0whYqenB608OP4gJmVUHIk 86Repd58CqRSIpPohD4XGB0sUPL6pRf6t3VKa1F59vfJMcqLs8Glt8fBzVlcN2vxWmPY y86pRHLVd2C+7VcUO9ynh9Xoq0tLfGr1CvRw/CVkpWN/six2hVZrrHjuj6GzPL1i8BzM 4i3B911bTmAmccNt3VDRbLFsj0MYrzc3jGZ2SS4tT3lac5xOa1CNNto83l3bEM1Qwcvu FUwQS5nPO0TknmwQlluLVLCN2vTEn295Ua2RZnDGbUutlY4JINVRS2VMDyee1of4gthU Uc5w== 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=wOysoelzRnYOrkG2Z14SpjF49EYeBD1nfmQf5XQ3/pk=; b=Xerxa7kXbCo6+CLCwfGOIc6+fSRvtxyKbTRvj9DoLmSmMox2beg4gz3VtJoMfcsKkI S+hn6H1c/IK0KhB61YUm5u8SopU3LZTq0+JEIg65tjgwSD4aBwZ1LQdQtLd+CiKCx6TW wcX6C+y13RVSgXxYENBxvgjk6pH3VhW5a8ItLi2U/h+j/1U4kNQ/HiZz5omrJzhdfta+ 57f4M+x7C97IVyyLG3B2Pvip3aYpl2nfPHViZC0meQhullW+Jm/iEUnSFjpMVs1zWmZ1 oJns/QAYJvAoHmJX/+0kLwGi1Zbj5VnZHkCCo5Tswuf0BKgioDCxgbtJSU2jO7IfMXzA zVqA== X-Gm-Message-State: AOAM530qvfdjkj5OQIPN0wSybQiI/8nfSmWeu7baZ7GVZipVyGyRTMoJ 6C9u7ybrfs5Z9PHY8RIiSas= X-Google-Smtp-Source: ABdhPJxunpBISIifFPuab4Mg/GPMoxrcKWPdMAgQFoEi64HcjCUlfzDCfXn5kYEf2FICI5manF7e0w== X-Received: by 2002:a92:cda8:: with SMTP id g8mr4047858ild.286.1616619583331; Wed, 24 Mar 2021 13:59:43 -0700 (PDT) Received: from [127.0.1.1] ([172.242.244.146]) by smtp.gmail.com with ESMTPSA id s5sm1601304ild.13.2021.03.24.13.59.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Mar 2021 13:59:43 -0700 (PDT) Subject: [bpf PATCH 1/2] bpf, sockmap: fix sk->prot unhash op reset From: John Fastabend To: john.fastabend@gmail.com, andrii@kernel.org, daniel@iogearbox.net, ast@fb.com Cc: xiyou.wangcong@gmail.com, bpf@vger.kernel.org, netdev@vger.kernel.org, lmb@cloudflare.com Date: Wed, 24 Mar 2021 13:59:29 -0700 Message-ID: <161661956953.28508.2297266338306692603.stgit@john-Precision-5820-Tower> In-Reply-To: <161661943080.28508.5809575518293376322.stgit@john-Precision-5820-Tower> References: <161661943080.28508.5809575518293376322.stgit@john-Precision-5820-Tower> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net In '4da6a196f93b1' we fixed a potential unhash loop caused when a TLS socket in a sockmap was removed from the sockmap. This happened because the unhash operation on the TLS ctx continued to point at the sockmap implementation of unhash even though the psock has already been removed. The sockmap unhash handler when a psock is removed does the following, void sock_map_unhash(struct sock *sk) { void (*saved_unhash)(struct sock *sk); struct sk_psock *psock; rcu_read_lock(); psock = sk_psock(sk); if (unlikely(!psock)) { rcu_read_unlock(); if (sk->sk_prot->unhash) sk->sk_prot->unhash(sk); return; } [...] } The unlikely() case is there to handle the case where psock is detached but the proto ops have not been updated yet. But, in the above case with TLS and removed psock we never fixed sk_prot->unhash() and unhash() points back to sock_map_unhash resulting in a loop. To fix this we added this bit of code, static inline void sk_psock_restore_proto(struct sock *sk, struct sk_psock *psock) { sk->sk_prot->unhash = psock->saved_unhash; This will set the sk_prot->unhash back to its saved value. This is the correct callback for a TLS socket that has been removed from the sock_map. Unfortunately, this also overwrites the unhash pointer for all psocks. We effectively break sockmap unhash handling for any future socks. Omitting the unhash operation will leave stale entries in the map if a socket transition through unhash, but does not do close() op. To fix handle similar to write_space and rewrite it in the TLS update hook. This way the TLS enabled socket will point to the saved unhash() handler. Fixes: 4da6a196f93b1 ("bpf: Sockmap/tls, during free we may call tcp_bpf_unhash() in loop") Reported-by: Cong Wang Reported-by: Lorenz Bauer Signed-off-by: John Fastabend --- include/linux/skmsg.h | 1 - net/tls/tls_main.c | 6 ++++++ 2 files changed, 6 insertions(+), 1 deletion(-) diff --git a/include/linux/skmsg.h b/include/linux/skmsg.h index 8edbbf5f2f93..f6009fe9c9ac 100644 --- a/include/linux/skmsg.h +++ b/include/linux/skmsg.h @@ -349,7 +349,6 @@ static inline void sk_psock_update_proto(struct sock *sk, static inline void sk_psock_restore_proto(struct sock *sk, struct sk_psock *psock) { - sk->sk_prot->unhash = psock->saved_unhash; if (inet_csk_has_ulp(sk)) { tcp_update_ulp(sk, psock->sk_proto, psock->saved_write_space); } else { diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c index 47b7c5334c34..ecb5634b4c4a 100644 --- a/net/tls/tls_main.c +++ b/net/tls/tls_main.c @@ -754,6 +754,12 @@ static void tls_update(struct sock *sk, struct proto *p, ctx = tls_get_ctx(sk); if (likely(ctx)) { + /* TLS does not have an unhash proto in SW cases, but we need + * to ensure we stop using the sock_map unhash routine because + * the associated psock is being removed. So use the original + * unhash handler. + */ + WRITE_ONCE(sk->sk_prot->unhash, p->unhash); ctx->sk_write_space = write_space; ctx->sk_proto = p; } else {