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=-7.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 00B70C04E87 for ; Fri, 17 May 2019 21:51:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C4D532166E for ; Fri, 17 May 2019 21:51:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="AFWZIX9S" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728272AbfEQVvw (ORCPT ); Fri, 17 May 2019 17:51:52 -0400 Received: from mail-pf1-f193.google.com ([209.85.210.193]:40036 "EHLO mail-pf1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727239AbfEQVvw (ORCPT ); Fri, 17 May 2019 17:51:52 -0400 Received: by mail-pf1-f193.google.com with SMTP id u17so4295551pfn.7; Fri, 17 May 2019 14:51:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=vKTywSie20PHVC+gh3ALmwP1wNcXOGPfZhP6bhLQuLg=; b=AFWZIX9SpWdoJ+jkt6VyXA7FgBbBpVlj5cEIBtlFAUKj4eQEsCPhK/l6iqZWZN2M9a +xZraq+SMdPEYEZtZT1BRQrLOxd4SIivN6kecQcDIctFbfBOmFkhObmx7cMzYOykiehp 1d/hQ4jqkYrU8p4jfWIdYaDoIQw4z7re1kVnNM5gpjlVpOE2fWfK8JUt7VV/d0h492FK jpdG1C1NK7Mh/lxCNhT5RmBKvFrbWxvJg4GoHoxVbcpoSSlKyuING0CJb47OaNV5ssTB A46gQcpPfXYS/ju61utxO6r1nKNy704lf2A2+xkO33uH6oUi492lRUl/2yu07njc+4WX z2Vw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=vKTywSie20PHVC+gh3ALmwP1wNcXOGPfZhP6bhLQuLg=; b=dDzVRUR92KuLwfhGJUIIKAXbFMhL6WB+pC92+raW92FeoAR6njLxY2ZGHytXX3OtpI NpiBX/i+cCucdeCRw2qDKz5AfnE5ycUcksVCuZ9WDEDyY7ZoCokmEVkpU4ppsqqU42Ti GcNa4pQY2Nqx8q8RXEpUy6HlG7h3m+9qxvzeJ7C0Oq9/9MVldmzuUdbm3FtJmvZzq2oq dhMlg6JIXFNzIW5Yy/KPk314yU/yov6CeKG7ISwv0vpItr+oPXrCPgg1S2xhPJ/c4nsD 5MrbksGRcAbWGZ0AV9uozMQd9E4nlBGUxKdPRZiQIPj5xBfYYZuh9nc6nOnP5KWDQGmb Jd1g== X-Gm-Message-State: APjAAAVyKo+YsX74Z1u5E+fqhkz33X+vTDouV/GEdZ11v0wOQaquOtio MIYqmP/5hr5oie2kbN+wNNU= X-Google-Smtp-Source: APXvYqxtr3rvkPAN7bisoVJOG3FCjvRT171MsV4nnVbCh1CvWumqd1A8T2Avg+su4rkzlYPcY0cIng== X-Received: by 2002:a62:7608:: with SMTP id r8mr62372435pfc.190.1558129911485; Fri, 17 May 2019 14:51:51 -0700 (PDT) Received: from [192.168.86.235] (c-73-241-150-70.hsd1.ca.comcast.net. [73.241.150.70]) by smtp.gmail.com with ESMTPSA id i7sm5132014pfo.19.2019.05.17.14.51.49 (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Fri, 17 May 2019 14:51:50 -0700 (PDT) Subject: Re: [PATCH bpf] bpf: Check sk_fullsock() before returning from bpf_sk_lookup() To: Martin KaFai Lau , bpf@vger.kernel.org, netdev@vger.kernel.org Cc: Alexei Starovoitov , Daniel Borkmann , kernel-team@fb.com, Joe Stringer References: <20190517212117.2792415-1-kafai@fb.com> From: Eric Dumazet Message-ID: <6dc01cb7-cdd4-8a71-b602-0052b7aadfb7@gmail.com> Date: Fri, 17 May 2019 14:51:48 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190517212117.2792415-1-kafai@fb.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 5/17/19 2:21 PM, Martin KaFai Lau wrote: > The BPF_FUNC_sk_lookup_xxx helpers return RET_PTR_TO_SOCKET_OR_NULL. > Meaning a fullsock ptr and its fullsock's fields in bpf_sock can be > accessed, e.g. type, protocol, mark and priority. > Some new helper, like bpf_sk_storage_get(), also expects > ARG_PTR_TO_SOCKET is a fullsock. > > bpf_sk_lookup() currently calls sk_to_full_sk() before returning. > However, the ptr returned from sk_to_full_sk() is not guaranteed > to be a fullsock. For example, it cannot get a fullsock if sk > is in TCP_TIME_WAIT. > > This patch checks for sk_fullsock() before returning. If it is not > a fullsock, sock_gen_put() is called if needed and then returns NULL. > > Fixes: 6acc9b432e67 ("bpf: Add helper to retrieve socket in BPF") > Cc: Joe Stringer > Signed-off-by: Martin KaFai Lau > --- > net/core/filter.c | 16 ++++++++++++++-- > 1 file changed, 14 insertions(+), 2 deletions(-) > > diff --git a/net/core/filter.c b/net/core/filter.c > index 55bfc941d17a..85def5a20aaf 100644 > --- a/net/core/filter.c > +++ b/net/core/filter.c > @@ -5337,8 +5337,14 @@ __bpf_sk_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len, > struct sock *sk = __bpf_skc_lookup(skb, tuple, len, caller_net, > ifindex, proto, netns_id, flags); > > - if (sk) > + if (sk) { > sk = sk_to_full_sk(sk); > + if (!sk_fullsock(sk)) { > + if (!sock_flag(sk, SOCK_RCU_FREE)) > + sock_gen_put(sk); This looks a bit convoluted/weird. What about telling/asking __bpf_skc_lookup() to not return a non fullsock instead ? > + return NULL; > + } > + } > > return sk; > } > @@ -5369,8 +5375,14 @@ bpf_sk_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len, > struct sock *sk = bpf_skc_lookup(skb, tuple, len, proto, netns_id, > flags); > > - if (sk) > + if (sk) { > sk = sk_to_full_sk(sk); > + if (!sk_fullsock(sk)) { > + if (!sock_flag(sk, SOCK_RCU_FREE)) > + sock_gen_put(sk); > + return NULL; > + } > + } > > return sk; > } >