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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 CC582C433DF for ; Mon, 1 Jun 2020 18:18:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AA63E2068D for ; Mon, 1 Jun 2020 18:18:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591035504; bh=wuQqh8fOhNvY6d10GqxHYqqVtOT+Ne5Cw+miRVcHsCA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=rjsJywMKuQqjvMzM/IinsRok1AAO7BdNx15Fxkexb/HQo5OVHaQ8ACgxcxwn+xCnk X9VvoP+8Wo7zHQXSTOCvYqqtF4unR/TM/V0lcjdmzV1zGKM1cVtSjdAjValkdP3/Cf X1kYEDW0ydMMpnAKawSUZKGATAle1z3NKy7s7Xu8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731930AbgFASSX (ORCPT ); Mon, 1 Jun 2020 14:18:23 -0400 Received: from mail.kernel.org ([198.145.29.99]:39910 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731662AbgFASSR (ORCPT ); Mon, 1 Jun 2020 14:18:17 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id AEA0D2068D; Mon, 1 Jun 2020 18:18:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591035496; bh=wuQqh8fOhNvY6d10GqxHYqqVtOT+Ne5Cw+miRVcHsCA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pTp0O2fLr/IagMsoMxaDyjcmITsiBZLCF8mOsjwLffapjEzdq7XSig00/Gw9ibnfs ZZW8siW2YdSrnW3X0VyyddfsqzxDeSC/AyddOtE/FttBv/lsUbr5zXxu+FWL+HZuj5 n8EaKTJiojGMYIxDaJ+hBKc230dWiOAahWNCTO+s= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Nikolay Aleksandrov , David Ahern , "David S. Miller" Subject: [PATCH 5.6 168/177] nexthops: dont modify published nexthop groups Date: Mon, 1 Jun 2020 19:55:06 +0200 Message-Id: <20200601174102.142642028@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200601174048.468952319@linuxfoundation.org> References: <20200601174048.468952319@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Nikolay Aleksandrov commit 90f33bffa382598a32cc82abfeb20adc92d041b6 upstream. We must avoid modifying published nexthop groups while they might be in use, otherwise we might see NULL ptr dereferences. In order to do that we allocate 2 nexthoup group structures upon nexthop creation and swap between them when we have to delete an entry. The reason is that we can't fail nexthop group removal, so we can't handle allocation failure thus we move the extra allocation on creation where we can safely fail and return ENOMEM. Fixes: 430a049190de ("nexthop: Add support for nexthop groups") Signed-off-by: Nikolay Aleksandrov Signed-off-by: David Ahern Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- include/net/nexthop.h | 1 net/ipv4/nexthop.c | 91 +++++++++++++++++++++++++++++++------------------- 2 files changed, 59 insertions(+), 33 deletions(-) --- a/include/net/nexthop.h +++ b/include/net/nexthop.h @@ -70,6 +70,7 @@ struct nh_grp_entry { }; struct nh_group { + struct nh_group *spare; /* spare group for removals */ u16 num_nh; bool mpath; bool has_v4; --- a/net/ipv4/nexthop.c +++ b/net/ipv4/nexthop.c @@ -63,9 +63,16 @@ static void nexthop_free_mpath(struct ne int i; nhg = rcu_dereference_raw(nh->nh_grp); - for (i = 0; i < nhg->num_nh; ++i) - WARN_ON(nhg->nh_entries[i].nh); + for (i = 0; i < nhg->num_nh; ++i) { + struct nh_grp_entry *nhge = &nhg->nh_entries[i]; + WARN_ON(!list_empty(&nhge->nh_list)); + nexthop_put(nhge->nh); + } + + WARN_ON(nhg->spare == nhg); + + kfree(nhg->spare); kfree(nhg); } @@ -697,46 +704,53 @@ static void nh_group_rebalance(struct nh static void remove_nh_grp_entry(struct net *net, struct nh_grp_entry *nhge, struct nl_info *nlinfo) { + struct nh_grp_entry *nhges, *new_nhges; struct nexthop *nhp = nhge->nh_parent; struct nexthop *nh = nhge->nh; - struct nh_grp_entry *nhges; - struct nh_group *nhg; - bool found = false; - int i; + struct nh_group *nhg, *newg; + int i, j; WARN_ON(!nh); - list_del(&nhge->nh_list); - nhg = rtnl_dereference(nhp->nh_grp); - nhges = nhg->nh_entries; - for (i = 0; i < nhg->num_nh; ++i) { - if (found) { - nhges[i-1].nh = nhges[i].nh; - nhges[i-1].weight = nhges[i].weight; - list_del(&nhges[i].nh_list); - list_add(&nhges[i-1].nh_list, &nhges[i-1].nh->grp_list); - } else if (nhg->nh_entries[i].nh == nh) { - found = true; - } - } + newg = nhg->spare; - if (WARN_ON(!found)) + /* last entry, keep it visible and remove the parent */ + if (nhg->num_nh == 1) { + remove_nexthop(net, nhp, nlinfo); return; + } - nhg->num_nh--; - nhg->nh_entries[nhg->num_nh].nh = NULL; + newg->has_v4 = nhg->has_v4; + newg->mpath = nhg->mpath; + newg->num_nh = nhg->num_nh; - nh_group_rebalance(nhg); + /* copy old entries to new except the one getting removed */ + nhges = nhg->nh_entries; + new_nhges = newg->nh_entries; + for (i = 0, j = 0; i < nhg->num_nh; ++i) { + /* current nexthop getting removed */ + if (nhg->nh_entries[i].nh == nh) { + newg->num_nh--; + continue; + } - nexthop_put(nh); + list_del(&nhges[i].nh_list); + new_nhges[j].nh_parent = nhges[i].nh_parent; + new_nhges[j].nh = nhges[i].nh; + new_nhges[j].weight = nhges[i].weight; + list_add(&new_nhges[j].nh_list, &new_nhges[j].nh->grp_list); + j++; + } + + nh_group_rebalance(newg); + rcu_assign_pointer(nhp->nh_grp, newg); + + list_del(&nhge->nh_list); + nexthop_put(nhge->nh); if (nlinfo) nexthop_notify(RTM_NEWNEXTHOP, nhp, nlinfo); - - /* if this group has no more entries then remove it */ - if (!nhg->num_nh) - remove_nexthop(net, nhp, nlinfo); } static void remove_nexthop_from_groups(struct net *net, struct nexthop *nh, @@ -746,6 +760,9 @@ static void remove_nexthop_from_groups(s list_for_each_entry_safe(nhge, tmp, &nh->grp_list, nh_list) remove_nh_grp_entry(net, nhge, nlinfo); + + /* make sure all see the newly published array before releasing rtnl */ + synchronize_rcu(); } static void remove_nexthop_group(struct nexthop *nh, struct nl_info *nlinfo) @@ -759,10 +776,7 @@ static void remove_nexthop_group(struct if (WARN_ON(!nhge->nh)) continue; - list_del(&nhge->nh_list); - nexthop_put(nhge->nh); - nhge->nh = NULL; - nhg->num_nh--; + list_del_init(&nhge->nh_list); } } @@ -1085,6 +1099,7 @@ static struct nexthop *nexthop_create_gr { struct nlattr *grps_attr = cfg->nh_grp; struct nexthop_grp *entry = nla_data(grps_attr); + u16 num_nh = nla_len(grps_attr) / sizeof(*entry); struct nh_group *nhg; struct nexthop *nh; int i; @@ -1095,12 +1110,21 @@ static struct nexthop *nexthop_create_gr nh->is_group = 1; - nhg = nexthop_grp_alloc(nla_len(grps_attr) / sizeof(*entry)); + nhg = nexthop_grp_alloc(num_nh); if (!nhg) { kfree(nh); return ERR_PTR(-ENOMEM); } + /* spare group used for removals */ + nhg->spare = nexthop_grp_alloc(num_nh); + if (!nhg) { + kfree(nhg); + kfree(nh); + return NULL; + } + nhg->spare->spare = nhg; + for (i = 0; i < nhg->num_nh; ++i) { struct nexthop *nhe; struct nh_info *nhi; @@ -1132,6 +1156,7 @@ out_no_nh: for (; i >= 0; --i) nexthop_put(nhg->nh_entries[i].nh); + kfree(nhg->spare); kfree(nhg); kfree(nh);