From patchwork Mon Sep 21 14:36:54 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dmitry Safonov X-Patchwork-Id: 1368453 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=quarantine dis=none) header.from=arista.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=arista.com header.i=@arista.com header.a=rsa-sha256 header.s=googlenew header.b=Q001+qfE; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4Bw6VL36r0z9sVj for ; Tue, 22 Sep 2020 00:37:46 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727917AbgIUOhP (ORCPT ); Mon, 21 Sep 2020 10:37:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42636 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727393AbgIUOhM (ORCPT ); Mon, 21 Sep 2020 10:37:12 -0400 Received: from mail-wr1-x441.google.com (mail-wr1-x441.google.com [IPv6:2a00:1450:4864:20::441]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 69EEFC0613D2 for ; Mon, 21 Sep 2020 07:37:12 -0700 (PDT) Received: by mail-wr1-x441.google.com with SMTP id o5so13012032wrn.13 for ; Mon, 21 Sep 2020 07:37:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arista.com; s=googlenew; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=/qlLBmSLkXX8+VWho1l+4lvAqtyGS8XDHRWiRzbfdT0=; b=Q001+qfEfU11Y7UoINCguwe49yZ95OIa3Dtvsd2N+mQGKjbZp+DAbLebQLXtUGBb49 enuj+gcu0OkBdDGQJ83p0ylqjAoQOtC/YfSYOoQA3hD3KR37inUKZgW8tGJWT8yk+VeX q377TB41SenHuTgpNx44CFEnjNNqF3DzJpmwdl/7cr97Q33RBA3029gMF/qVl+LMNghR JGLjS0g1/v/YW3C3qHy4zL3LY80S9K/SbwQKNGYq1AIfUMMa/NtA/MiE+TlpDoS+N8/U vkeXJegOlczyOceUflvCrMaXksoMhSHVXE+n8PFYRn5FR0bNPWcl2W2vkHGTtS1/yvZV LhRg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=/qlLBmSLkXX8+VWho1l+4lvAqtyGS8XDHRWiRzbfdT0=; b=DlqWs5QfV9vQAvb14gIPduzeZ52ny9G0ppNmqATnxC7OPvQUFbmLL7xsEMsmZSjUkA /Rj0rU1Cahc3GqtSHpRryW1VKPoZCuAQTO2QPIjPVCP2JLFxPaB6Ob36ngqYXUWcHJ3h GKBWbY2vTQgyCMWWmnymAKe/FtdVHT6EUYkg6s0m+q8/dMWf35rWh/b6MthIkubxqbYJ eI8Q4XSQN+L8h+XVPzd/IXyOtdzQbsaCyJhl6s6nJZr+BmlpqRaZxE5mV3g3417RUAHh pxHqGN4levSSOSfMtxAFP6nz/KLUxFdZbxKypEhP4hy6jlZPqkVTKaAwyOdcm85Bmx1z jI9w== X-Gm-Message-State: AOAM533YRhhrZnXpLt7IaRczpVR/n9MJj40OkbNQ3dwDBVe9JLVPI7z2 KTpO3P/slHZ9hTipdOM2ZLJl+g== X-Google-Smtp-Source: ABdhPJyeDwt3llJ1iiPKlXmXG5HaT72EzX6BpOjM8GwSM6TDgvyQwVjapGSKAZO2Up1n/3L5Hn4W4w== X-Received: by 2002:a5d:4d51:: with SMTP id a17mr96505wru.248.1600699031023; Mon, 21 Sep 2020 07:37:11 -0700 (PDT) Received: from localhost.localdomain ([2a02:8084:e84:2480:228:f8ff:fe6f:83a8]) by smtp.gmail.com with ESMTPSA id c14sm20370753wrv.12.2020.09.21.07.37.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 21 Sep 2020 07:37:10 -0700 (PDT) From: Dmitry Safonov To: linux-kernel@vger.kernel.org Cc: Dmitry Safonov <0x7f454c46@gmail.com>, Dmitry Safonov , "David S. Miller" , Florian Westphal , Herbert Xu , Jakub Kicinski , Johannes Berg , Steffen Klassert , Stephen Suryaputra , netdev@vger.kernel.org Subject: [PATCH v3 4/7] netlink/compat: Append NLMSG_DONE/extack to frag_list Date: Mon, 21 Sep 2020 15:36:54 +0100 Message-Id: <20200921143657.604020-5-dima@arista.com> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200921143657.604020-1-dima@arista.com> References: <20200921143657.604020-1-dima@arista.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Modules those use netlink may supply a 2nd skb, (via frag_list) that contains an alternative data set meant for applications using 32bit compatibility mode. In such a case, netlink_recvmsg will use this 2nd skb instead of the original one. Without this patch, such compat applications will retrieve all netlink dump data, but will then get an unexpected EOF. Cc: Johannes Berg Signed-off-by: Florian Westphal Signed-off-by: Dmitry Safonov Reviewed-by: Johannes Berg --- net/netlink/af_netlink.c | 47 ++++++++++++++++++++++++++++------------ 1 file changed, 33 insertions(+), 14 deletions(-) diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index d2d1448274f5..de12dd3136f9 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -2186,13 +2186,35 @@ EXPORT_SYMBOL(__nlmsg_put); * It would be better to create kernel thread. */ +static int netlink_dump_done(struct netlink_sock *nlk, struct sk_buff *skb, + struct netlink_callback *cb, + struct netlink_ext_ack *extack) +{ + struct nlmsghdr *nlh; + + nlh = nlmsg_put_answer(skb, cb, NLMSG_DONE, sizeof(nlk->dump_done_errno), + NLM_F_MULTI | cb->answer_flags); + if (WARN_ON(!nlh)) + return -ENOBUFS; + + nl_dump_check_consistent(cb, nlh); + memcpy(nlmsg_data(nlh), &nlk->dump_done_errno, sizeof(nlk->dump_done_errno)); + + if (extack->_msg && nlk->flags & NETLINK_F_EXT_ACK) { + nlh->nlmsg_flags |= NLM_F_ACK_TLVS; + if (!nla_put_string(skb, NLMSGERR_ATTR_MSG, extack->_msg)) + nlmsg_end(skb, nlh); + } + + return 0; +} + static int netlink_dump(struct sock *sk) { struct netlink_sock *nlk = nlk_sk(sk); struct netlink_ext_ack extack = {}; struct netlink_callback *cb; struct sk_buff *skb = NULL; - struct nlmsghdr *nlh; struct module *module; int err = -ENOBUFS; int alloc_min_size; @@ -2258,22 +2280,19 @@ static int netlink_dump(struct sock *sk) return 0; } - nlh = nlmsg_put_answer(skb, cb, NLMSG_DONE, - sizeof(nlk->dump_done_errno), - NLM_F_MULTI | cb->answer_flags); - if (WARN_ON(!nlh)) + if (netlink_dump_done(nlk, skb, cb, &extack)) goto errout_skb; - nl_dump_check_consistent(cb, nlh); - - memcpy(nlmsg_data(nlh), &nlk->dump_done_errno, - sizeof(nlk->dump_done_errno)); - - if (extack._msg && nlk->flags & NETLINK_F_EXT_ACK) { - nlh->nlmsg_flags |= NLM_F_ACK_TLVS; - if (!nla_put_string(skb, NLMSGERR_ATTR_MSG, extack._msg)) - nlmsg_end(skb, nlh); +#ifdef CONFIG_COMPAT_NETLINK_MESSAGES + /* frag_list skb's data is used for compat tasks + * and the regular skb's data for normal (non-compat) tasks. + * See netlink_recvmsg(). + */ + if (unlikely(skb_shinfo(skb)->frag_list)) { + if (netlink_dump_done(nlk, skb_shinfo(skb)->frag_list, cb, &extack)) + goto errout_skb; } +#endif if (sk_filter(sk, skb)) kfree_skb(skb);