netdev - [PATCH net-next 11/13] net: ipv6: route: perform strict checks also for doit handlers

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Date:   Thu, 17 Jan 2019 14:52:58 -0800
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     davem@...emloft.net, dsahern@...il.com
Cc:     netdev@...r.kernel.org, oss-drivers@...ronome.com,
        Jakub Kicinski <jakub.kicinski@...ronome.com>
Subject: [PATCH net-next 11/13] net: ipv6: route: perform strict checks also for doit handlers

Make RTM_GETROUTE's doit handler use strict checks when
NETLINK_F_STRICT_CHK is set.

Signed-off-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
---
 net/ipv6/route.c | 70 ++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 68 insertions(+), 2 deletions(-)

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 964491cf3672..dc066fdf7e46 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -4812,6 +4812,73 @@ int rt6_dump_route(struct fib6_info *rt, void *p_arg)
 			     arg->cb->nlh->nlmsg_seq, flags);
 }
 
+static int inet6_rtm_valid_getroute_req(struct sk_buff *skb,
+					const struct nlmsghdr *nlh,
+					struct nlattr **tb,
+					struct netlink_ext_ack *extack)
+{
+	struct rtmsg *rtm;
+	int i, err;
+
+	if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*rtm))) {
+		NL_SET_ERR_MSG_MOD(extack,
+				   "Invalid header for get route request");
+		return -EINVAL;
+	}
+
+	if (!netlink_strict_get_check(skb))
+		return nlmsg_parse(nlh, sizeof(*rtm), tb, RTA_MAX,
+				   rtm_ipv6_policy, extack);
+
+	rtm = nlmsg_data(nlh);
+	if ((rtm->rtm_src_len && rtm->rtm_src_len != 128) ||
+	    (rtm->rtm_dst_len && rtm->rtm_dst_len != 128) ||
+	    rtm->rtm_table || rtm->rtm_protocol || rtm->rtm_scope ||
+	    rtm->rtm_type) {
+		NL_SET_ERR_MSG_MOD(extack, "Invalid values in header for get route request");
+		return -EINVAL;
+	}
+	if (rtm->rtm_flags & ~RTM_F_FIB_MATCH) {
+		NL_SET_ERR_MSG_MOD(extack,
+				   "Invalid flags for get route request");
+		return -EINVAL;
+	}
+
+	err = nlmsg_parse_strict(nlh, sizeof(*rtm), tb, RTA_MAX,
+				 rtm_ipv6_policy, extack);
+	if (err)
+		return err;
+
+	if ((tb[RTA_SRC] && !rtm->rtm_src_len) ||
+	    (tb[RTA_DST] && !rtm->rtm_dst_len)) {
+		NL_SET_ERR_MSG_MOD(extack, "rtm_src_len and rtm_dst_len must be 128 for IPv6");
+		return -EINVAL;
+	}
+
+	for (i = 0; i <= RTA_MAX; i++) {
+		if (!tb[i])
+			continue;
+
+		switch (i) {
+		case RTA_SRC:
+		case RTA_DST:
+		case RTA_IIF:
+		case RTA_OIF:
+		case RTA_MARK:
+		case RTA_UID:
+		case RTA_SPORT:
+		case RTA_DPORT:
+		case RTA_IP_PROTO:
+			break;
+		default:
+			NL_SET_ERR_MSG_MOD(extack, "Unsupported attribute in get route request");
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
 static int inet6_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
 			      struct netlink_ext_ack *extack)
 {
@@ -4826,8 +4893,7 @@ static int inet6_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
 	struct flowi6 fl6 = {};
 	bool fibmatch;
 
-	err = nlmsg_parse(nlh, sizeof(*rtm), tb, RTA_MAX, rtm_ipv6_policy,
-			  extack);
+	err = inet6_rtm_valid_getroute_req(in_skb, nlh, tb, extack);
 	if (err < 0)
 		goto errout;
 
-- 
2.19.2