From patchwork Thu Apr 15 03:33:41 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathon Reinhart X-Patchwork-Id: 12204201 X-Patchwork-Delegate: kuba@kernel.org 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=-15.8 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,USER_AGENT_GIT 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 45DB7C433ED for ; Thu, 15 Apr 2021 03:34:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1313C6103E for ; Thu, 15 Apr 2021 03:34:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229731AbhDODfB (ORCPT ); Wed, 14 Apr 2021 23:35:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35924 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229481AbhDODfA (ORCPT ); Wed, 14 Apr 2021 23:35:00 -0400 Received: from mail-qk1-x730.google.com (mail-qk1-x730.google.com [IPv6:2607:f8b0:4864:20::730]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6F1F6C061574 for ; Wed, 14 Apr 2021 20:34:38 -0700 (PDT) Received: by mail-qk1-x730.google.com with SMTP id b139so18490010qkc.10 for ; Wed, 14 Apr 2021 20:34:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=0gr9xoLhNOvNDy6SbuGKMIg7J3bMcVhUGfITNxZn5gE=; b=lqeM7+mqUZJ4iJbH0AohYBqE3msXNTZY5AuqyXLt3EoyFFkSWLtzCvYuTDr1XIq5PU jmtRl1tkJRZE1rfbQitN2Y8fobH612+kO9N74Gp2Oubp35vdE/8yDgtMOckMOdNPhIJs cUkWPe/LGIS/FOf2nrI2gHJZK4tO5MBolRpgQIUB2y5t1w7vDxM/VLXr0JsWYVyQ+wTD Kd1fSK3g+wGTka5o2A3EEDaVhVn4JnogHsTHgjP5zBdRt2N2UGV0lTZlCj3HPo7WkXnT j85WE+qc9xGg43Ao6OjxcSlF5hd40O+rIQZSIW6bmxNaB2Rh0V/emwdicHi3cTIdqCkw Y3vw== 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=0gr9xoLhNOvNDy6SbuGKMIg7J3bMcVhUGfITNxZn5gE=; b=BcIbSGC25Y5u0hHsuGazMFZnzLGf7XWnEXI2PMWTHtUn/v137Oag23PyaGUWamBlJP 8YZdtTCK3A2M62fm0N8/pLmlFCdW4SZhRh3o5VQ27/JFlDyfeNeK6oF7Owoa9VA0FJsj j8KMXimP2TlOGXk9h1haDegpPK2EVoOto8xTvT9oWTSiV6NyMXKOAEZJP37aqyTD/OMF PNIF2AoVRuZq1ydkocFROw9+FbpEGptSVtzVhIfsIUnqeISeb/efQNdM0cM5zVb2YYt6 hSh78ilOEZb8ZQDAv7RveochEvI3e+X9Z2JT8/lYZjP4CzgHTFjfkZOJB1O2qwSxhBH9 Fg1A== X-Gm-Message-State: AOAM5319/szQ4Hcq5mNRPG42W+LzsU5uEMHocf3V7jbRxoUUp7xrSJ7P NFMDzJvnnnZq4f4Brpla7WV4mjdUDf4K4g== X-Google-Smtp-Source: ABdhPJyn5HCvt1TPpHddafmQ+MD6WIBT1/+ozHFtiUCKc9fUQ6aE7RcIJz5JkVwDImA/Qz2dv+nThw== X-Received: by 2002:a05:620a:22a2:: with SMTP id p2mr1675109qkh.314.1618457677466; Wed, 14 Apr 2021 20:34:37 -0700 (PDT) Received: from jrr-vaio.internal.cc-sw.com (2603-6010-7221-eda3-0000-0000-0000-1d7d.res6.spectrum.com. [2603:6010:7221:eda3::1d7d]) by smtp.gmail.com with ESMTPSA id 81sm1080029qkl.121.2021.04.14.20.34.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 14 Apr 2021 20:34:36 -0700 (PDT) From: Jonathon Reinhart To: netdev@vger.kernel.org Cc: Jonathon Reinhart , "David S. Miller" , Hideaki YOSHIFUJI , David Ahern , Jakub Kicinski , Christian Brauner Subject: [PATCH RESEND net-next] net: Make tcp_allowed_congestion_control readonly in non-init netns Date: Wed, 14 Apr 2021 23:33:41 -0400 Message-Id: <20210415033341.1147-1-jonathon.reinhart@gmail.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210413070848.7261-1-jonathon.reinhart@gmail.com> References: <20210413070848.7261-1-jonathon.reinhart@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org Currently, tcp_allowed_congestion_control is global and writable; writing to it in any net namespace will leak into all other net namespaces. tcp_available_congestion_control and tcp_allowed_congestion_control are the only sysctls in ipv4_net_table (the per-netns sysctl table) with a NULL data pointer; their handlers (proc_tcp_available_congestion_control and proc_allowed_congestion_control) have no other way of referencing a struct net. Thus, they operate globally. Because ipv4_net_table does not use designated initializers, there is no easy way to fix up this one "bad" table entry. However, the data pointer updating logic shouldn't be applied to NULL pointers anyway, so we instead force these entries to be read-only. These sysctls used to exist in ipv4_table (init-net only), but they were moved to the per-net ipv4_net_table, presumably without realizing that tcp_allowed_congestion_control was writable and thus introduced a leak. Because the intent of that commit was only to know (i.e. read) "which congestion algorithms are available or allowed", this read-only solution should be sufficient. The logic added in recent commit 31c4d2f160eb: ("net: Ensure net namespace isolation of sysctls") does not and cannot check for NULL data pointers, because other table entries (e.g. /proc/sys/net/netfilter/nf_log/) have .data=NULL but use other methods (.extra2) to access the struct net. Fixes: 9cb8e048e5d9 ("net/ipv4/sysctl: show tcp_{allowed, available}_congestion_control in non-initial netns") Signed-off-by: Jonathon Reinhart --- net/ipv4/sysctl_net_ipv4.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c index a09e466ce11d..a62934b9f15a 100644 --- a/net/ipv4/sysctl_net_ipv4.c +++ b/net/ipv4/sysctl_net_ipv4.c @@ -1383,9 +1383,19 @@ static __net_init int ipv4_sysctl_init_net(struct net *net) if (!table) goto err_alloc; - /* Update the variables to point into the current struct net */ - for (i = 0; i < ARRAY_SIZE(ipv4_net_table) - 1; i++) - table[i].data += (void *)net - (void *)&init_net; + for (i = 0; i < ARRAY_SIZE(ipv4_net_table) - 1; i++) { + if (table[i].data) { + /* Update the variables to point into + * the current struct net + */ + table[i].data += (void *)net - (void *)&init_net; + } else { + /* Entries without data pointer are global; + * Make them read-only in non-init_net ns + */ + table[i].mode &= ~0222; + } + } } net->ipv4.ipv4_hdr = register_net_sysctl(net, "net/ipv4", table);