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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 B1494C433E0 for ; Tue, 26 May 2020 19:33:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8764C20849 for ; Tue, 26 May 2020 19:33:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590521597; bh=JHG4u04g44eiuHlgDVIQOAvUt/HD3vMhtyq+qyyYGjM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ACXYaPr8trt2Q6ORi50PjerE5TvZCbfxxyGDmSyibaO9ZGukjWTihgPDF+dTE2cnL ZoV6YlzIPv4R+v6D3S3HUZs/5Mg7msEciq/8G13Cmhc7eYTSh+wqKh9yO6wVVOfATW ZKXU+KySkq5pwKRYhMRTkmUWu/yRUzR1Z0oXeYEo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390908AbgEZTdQ (ORCPT ); Tue, 26 May 2020 15:33:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:49186 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389802AbgEZS4X (ORCPT ); Tue, 26 May 2020 14:56:23 -0400 Received: from C02YQ0RWLVCF.internal.digitalocean.com (c-73-181-34-237.hsd1.co.comcast.net [73.181.34.237]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E3750208DB; Tue, 26 May 2020 18:56:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590519382; bh=JHG4u04g44eiuHlgDVIQOAvUt/HD3vMhtyq+qyyYGjM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=c2Frl8CyPeG4VaPQMlZpHfR1iGUOg7lt/7Hc+41dBrt3VvIidDgmSGYGvbY5vn+3c GUIZ2SF8fnowqH4oyaOVYu6lSJnYE9Wa1RxDw6qJvJvW8QJzwLS5QmZofZXFmh5wzU CoeHsWG4FQ07b2oKsCe4qQDNQs63RVAyuvu2vr8o= From: David Ahern To: netdev@vger.kernel.org Cc: davem@davemloft.net, kuba@kernel.org, nikolay@cumulusnetworks.com, David Ahern Subject: [PATCH net v2 2/5] nexthops: don't modify published nexthop groups Date: Tue, 26 May 2020 12:56:15 -0600 Message-Id: <20200526185618.43748-3-dsahern@kernel.org> X-Mailer: git-send-email 2.21.1 (Apple Git-122.3) In-Reply-To: <20200526185618.43748-1-dsahern@kernel.org> References: <20200526185618.43748-1-dsahern@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Nikolay Aleksandrov 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 --- include/net/nexthop.h | 1 + net/ipv4/nexthop.c | 91 +++++++++++++++++++++++++++---------------- 2 files changed, 59 insertions(+), 33 deletions(-) diff --git a/include/net/nexthop.h b/include/net/nexthop.h index c440ccc861fc..8a343519ed7a 100644 --- 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; diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c index b4b772f120a7..563f71bcb2d7 100644 --- a/net/ipv4/nexthop.c +++ b/net/ipv4/nexthop.c @@ -63,9 +63,16 @@ static void nexthop_free_mpath(struct nexthop *nh) 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_group *nhg) 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(struct net *net, struct nexthop *nh, 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 nexthop *nh, struct nl_info *nlinfo) 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_group(struct net *net, { 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_group(struct net *net, 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 @@ static struct nexthop *nexthop_create_group(struct net *net, for (; i >= 0; --i) nexthop_put(nhg->nh_entries[i].nh); + kfree(nhg->spare); kfree(nhg); kfree(nh); -- 2.21.1 (Apple Git-122.3)