Merge branch 'net-use-strict-checks-in-doit-handlers'

Jakub Kicinski says:

====================
net: use strict checks in doit handlers

This series extends strict argument checking to doit handlers
of the GET* nature.  This is a bit tricky since strict checking
flag has already been released..

iproute2 did not have a release with strick checks enabled,
and it will only need a minor one-liner to pass strick checks
after all the work that DaveA has already done.

Big thanks to Dave Ahern for help and guidence.

v2:
 - remove unnecessary check in patch 5 (Nicolas);
 - add path 7 (DaveA);
 - improve messages in patch 8 (DaveA).
====================

Signed-off-by: David S. Miller <[email protected]>

1 files changed, 70 insertions, 2 deletions

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index ce92f73cf104..99be68b15da0 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2763,6 +2763,75 @@ static struct sk_buff *inet_rtm_getroute_build_skb(__be32 src, __be32 dst,
 	return skb;
 }
 
+static int inet_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(extack,
+			       "ipv4: Invalid header for route get request");
+		return -EINVAL;
+	}
+
+	if (!netlink_strict_get_check(skb))
+		return nlmsg_parse(nlh, sizeof(*rtm), tb, RTA_MAX,
+				   rtm_ipv4_policy, extack);
+
+	rtm = nlmsg_data(nlh);
+	if ((rtm->rtm_src_len && rtm->rtm_src_len != 32) ||
+	    (rtm->rtm_dst_len && rtm->rtm_dst_len != 32) ||
+	    rtm->rtm_table || rtm->rtm_protocol ||
+	    rtm->rtm_scope || rtm->rtm_type) {
+		NL_SET_ERR_MSG(extack, "ipv4: Invalid values in header for route get request");
+		return -EINVAL;
+	}
+
+	if (rtm->rtm_flags & ~(RTM_F_NOTIFY |
+			       RTM_F_LOOKUP_TABLE |
+			       RTM_F_FIB_MATCH)) {
+		NL_SET_ERR_MSG(extack, "ipv4: Unsupported rtm_flags for route get request");
+		return -EINVAL;
+	}
+
+	err = nlmsg_parse_strict(nlh, sizeof(*rtm), tb, RTA_MAX,
+				 rtm_ipv4_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(extack, "ipv4: rtm_src_len and rtm_dst_len must be 32 for IPv4");
+		return -EINVAL;
+	}
+
+	for (i = 0; i <= RTA_MAX; i++) {
+		if (!tb[i])
+			continue;
+
+		switch (i) {
+		case RTA_IIF:
+		case RTA_OIF:
+		case RTA_SRC:
+		case RTA_DST:
+		case RTA_IP_PROTO:
+		case RTA_SPORT:
+		case RTA_DPORT:
+		case RTA_MARK:
+		case RTA_UID:
+			break;
+		default:
+			NL_SET_ERR_MSG(extack, "ipv4: Unsupported attribute in route get request");
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
 static int inet_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
 			     struct netlink_ext_ack *extack)
 {
@@ -2783,8 +2852,7 @@ static int inet_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
 	int err;
 	int mark;
 
-	err = nlmsg_parse(nlh, sizeof(*rtm), tb, RTA_MAX, rtm_ipv4_policy,
-			  extack);
+	err = inet_rtm_valid_getroute_req(in_skb, nlh, tb, extack);
 	if (err < 0)
 		return err;