Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752384AbdFERZy (ORCPT ); Mon, 5 Jun 2017 13:25:54 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:58088 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751516AbdFEQU5 (ORCPT ); Mon, 5 Jun 2017 12:20:57 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jan Moskyto Matejka , David Ahern , "David S. Miller" Subject: [PATCH 4.4 12/53] net: Improve handling of failures on link and route dumps Date: Mon, 5 Jun 2017 18:17:10 +0200 Message-Id: <20170605153037.881573102@linuxfoundation.org> X-Mailer: git-send-email 2.13.0 In-Reply-To: <20170605153037.105331684@linuxfoundation.org> References: <20170605153037.105331684@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5210 Lines: 205 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Ahern [ Upstream commit f6c5775ff0bfa62b072face6bf1d40f659f194b2 ] In general, rtnetlink dumps do not anticipate failure to dump a single object (e.g., link or route) on a single pass. As both route and link objects have grown via more attributes, that is no longer a given. netlink dumps can handle a failure if the dump function returns an error; specifically, netlink_dump adds the return code to the response if it is <= 0 so userspace is notified of the failure. The missing piece is the rtnetlink dump functions returning the error. Fix route and link dump functions to return the errors if no object is added to an skb (detected by skb->len != 0). IPv6 route dumps (rt6_dump_route) already return the error; this patch updates IPv4 and link dumps. Other dump functions may need to be ajusted as well. Reported-by: Jan Moskyto Matejka Signed-off-by: David Ahern Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/core/rtnetlink.c | 36 ++++++++++++++++++++++++------------ net/ipv4/fib_frontend.c | 15 +++++++++++---- net/ipv4/fib_trie.c | 26 ++++++++++++++------------ 3 files changed, 49 insertions(+), 28 deletions(-) --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -1458,13 +1458,13 @@ static int rtnl_dump_ifinfo(struct sk_bu cb->nlh->nlmsg_seq, 0, NLM_F_MULTI, ext_filter_mask); - /* If we ran out of room on the first message, - * we're in trouble - */ - WARN_ON((err == -EMSGSIZE) && (skb->len == 0)); - if (err < 0) - goto out; + if (err < 0) { + if (likely(skb->len)) + goto out; + + goto out_err; + } nl_dump_check_consistent(cb, nlmsg_hdr(skb)); cont: @@ -1472,10 +1472,12 @@ cont: } } out: + err = skb->len; +out_err: cb->args[1] = idx; cb->args[0] = h; - return skb->len; + return err; } int rtnl_nla_parse_ifla(struct nlattr **tb, const struct nlattr *head, int len) @@ -3127,8 +3129,12 @@ static int rtnl_bridge_getlink(struct sk err = br_dev->netdev_ops->ndo_bridge_getlink( skb, portid, seq, dev, filter_mask, NLM_F_MULTI); - if (err < 0 && err != -EOPNOTSUPP) - break; + if (err < 0 && err != -EOPNOTSUPP) { + if (likely(skb->len)) + break; + + goto out_err; + } } idx++; } @@ -3139,16 +3145,22 @@ static int rtnl_bridge_getlink(struct sk seq, dev, filter_mask, NLM_F_MULTI); - if (err < 0 && err != -EOPNOTSUPP) - break; + if (err < 0 && err != -EOPNOTSUPP) { + if (likely(skb->len)) + break; + + goto out_err; + } } idx++; } } + err = skb->len; +out_err: rcu_read_unlock(); cb->args[0] = idx; - return skb->len; + return err; } static inline size_t bridge_nlmsg_size(void) --- a/net/ipv4/fib_frontend.c +++ b/net/ipv4/fib_frontend.c @@ -757,7 +757,7 @@ static int inet_dump_fib(struct sk_buff unsigned int e = 0, s_e; struct fib_table *tb; struct hlist_head *head; - int dumped = 0; + int dumped = 0, err; if (nlmsg_len(cb->nlh) >= sizeof(struct rtmsg) && ((struct rtmsg *) nlmsg_data(cb->nlh))->rtm_flags & RTM_F_CLONED) @@ -777,20 +777,27 @@ static int inet_dump_fib(struct sk_buff if (dumped) memset(&cb->args[2], 0, sizeof(cb->args) - 2 * sizeof(cb->args[0])); - if (fib_table_dump(tb, skb, cb) < 0) - goto out; + err = fib_table_dump(tb, skb, cb); + if (err < 0) { + if (likely(skb->len)) + goto out; + + goto out_err; + } dumped = 1; next: e++; } } out: + err = skb->len; +out_err: rcu_read_unlock(); cb->args[1] = e; cb->args[0] = h; - return skb->len; + return err; } /* Prepare and feed intra-kernel routing request. --- a/net/ipv4/fib_trie.c +++ b/net/ipv4/fib_trie.c @@ -1906,6 +1906,8 @@ static int fn_trie_dump_leaf(struct key_ /* rcu_read_lock is hold by caller */ hlist_for_each_entry_rcu(fa, &l->leaf, fa_list) { + int err; + if (i < s_i) { i++; continue; @@ -1916,17 +1918,14 @@ static int fn_trie_dump_leaf(struct key_ continue; } - if (fib_dump_info(skb, NETLINK_CB(cb->skb).portid, - cb->nlh->nlmsg_seq, - RTM_NEWROUTE, - tb->tb_id, - fa->fa_type, - xkey, - KEYLENGTH - fa->fa_slen, - fa->fa_tos, - fa->fa_info, NLM_F_MULTI) < 0) { + err = fib_dump_info(skb, NETLINK_CB(cb->skb).portid, + cb->nlh->nlmsg_seq, RTM_NEWROUTE, + tb->tb_id, fa->fa_type, + xkey, KEYLENGTH - fa->fa_slen, + fa->fa_tos, fa->fa_info, NLM_F_MULTI); + if (err < 0) { cb->args[4] = i; - return -1; + return err; } i++; } @@ -1948,10 +1947,13 @@ int fib_table_dump(struct fib_table *tb, t_key key = cb->args[3]; while ((l = leaf_walk_rcu(&tp, key)) != NULL) { - if (fn_trie_dump_leaf(l, tb, skb, cb) < 0) { + int err; + + err = fn_trie_dump_leaf(l, tb, skb, cb); + if (err < 0) { cb->args[3] = key; cb->args[2] = count; - return -1; + return err; } ++count;