From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Ahern Subject: [PATCH v2 net-next 10/23] rtnetlink: Update rtnl_bridge_getlink for strict data checking Date: Sun, 7 Oct 2018 20:16:31 -0700 Message-ID: <20181008031644.15989-11-dsahern@kernel.org> References: <20181008031644.15989-1-dsahern@kernel.org> Cc: christian@brauner.io, jbenc@redhat.com, stephen@networkplumber.org, David Ahern To: netdev@vger.kernel.org, davem@davemloft.net Return-path: Received: from mail.kernel.org ([198.145.29.99]:42652 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726920AbeJHK0U (ORCPT ); Mon, 8 Oct 2018 06:26:20 -0400 In-Reply-To: <20181008031644.15989-1-dsahern@kernel.org> Sender: netdev-owner@vger.kernel.org List-ID: From: David Ahern Update rtnl_bridge_getlink for strict data checking. If the flag is set, the dump request is expected to have an ifinfomsg struct as the header potentially followed by one or more attributes. Any data passed in the header or as an attribute is taken as a request to influence the data returned. Only values supported by the dump handler are allowed to be non-0 or set in the request. At the moment only the IFLA_EXT_MASK attribute is supported. Signed-off-by: David Ahern --- net/core/rtnetlink.c | 70 ++++++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 57 insertions(+), 13 deletions(-) diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index 12fd52105005..e38e1f178611 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -4021,28 +4021,72 @@ int ndo_dflt_bridge_getlink(struct sk_buff *skb, u32 pid, u32 seq, } EXPORT_SYMBOL_GPL(ndo_dflt_bridge_getlink); +static int valid_bridge_getlink_req(const struct nlmsghdr *nlh, + bool strict_check, u32 *filter_mask, + struct netlink_ext_ack *extack) +{ + struct nlattr *tb[IFLA_MAX+1]; + int err, i; + + if (strict_check) { + struct ifinfomsg *ifm; + + if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*ifm))) { + NL_SET_ERR_MSG(extack, "Invalid header for bridge link dump"); + return -EINVAL; + } + + ifm = nlmsg_data(nlh); + if (ifm->__ifi_pad || ifm->ifi_type || ifm->ifi_flags || + ifm->ifi_change || ifm->ifi_index) { + NL_SET_ERR_MSG(extack, "Invalid values in header for bridge link dump request"); + return -EINVAL; + } + + err = nlmsg_parse_strict(nlh, sizeof(struct ifinfomsg), tb, + IFLA_MAX, ifla_policy, extack); + } else { + err = nlmsg_parse(nlh, sizeof(struct ifinfomsg), tb, + IFLA_MAX, ifla_policy, extack); + } + if (err < 0) + return err; + + /* new attributes should only be added with strict checking */ + for (i = 0; i <= IFLA_MAX; ++i) { + if (!tb[i]) + continue; + + switch (i) { + case IFLA_EXT_MASK: + *filter_mask = nla_get_u32(tb[i]); + break; + default: + if (strict_check) { + NL_SET_ERR_MSG(extack, "Unsupported attribute in bridge link dump request"); + return -EINVAL; + } + } + } + + return 0; +} + static int rtnl_bridge_getlink(struct sk_buff *skb, struct netlink_callback *cb) { + const struct nlmsghdr *nlh = cb->nlh; struct net *net = sock_net(skb->sk); struct net_device *dev; int idx = 0; u32 portid = NETLINK_CB(cb->skb).portid; - u32 seq = cb->nlh->nlmsg_seq; + u32 seq = nlh->nlmsg_seq; u32 filter_mask = 0; int err; - if (nlmsg_len(cb->nlh) > sizeof(struct ifinfomsg)) { - struct nlattr *extfilt; - - extfilt = nlmsg_find_attr(cb->nlh, sizeof(struct ifinfomsg), - IFLA_EXT_MASK); - if (extfilt) { - if (nla_len(extfilt) < sizeof(filter_mask)) - return -EINVAL; - - filter_mask = nla_get_u32(extfilt); - } - } + err = valid_bridge_getlink_req(nlh, cb->strict_check, &filter_mask, + cb->extack); + if (err < 0 && cb->strict_check) + return err; rcu_read_lock(); for_each_netdev_rcu(net, dev) { -- 2.11.0