Subject: [PATCH v2 net-next 20/23] net: Update netconf dump handlers for strict data checking

From: David Ahern <[email-masked]>
Date: Sun, 7 Oct 2018 20:16:41 -0700

From: David Ahern <[email-masked]>

Update inet_netconf_dump_devconf, inet6_netconf_dump_devconf, and
mpls_netconf_dump_devconf for strict data checking. If the flag is set,
the dump request is expected to have an netconfmsg struct as the header.
The struct only has the family member and no attributes can be appended.

Signed-off-by: David Ahern <[email-masked]>
---
 net/ipv4/devinet.c  | 22 +++++++++++++++++++---
 net/ipv6/addrconf.c | 22 +++++++++++++++++++---
 net/mpls/af_mpls.c  | 18 +++++++++++++++++-
 3 files changed, 55 insertions(+), 7 deletions(-)

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 6f2bbd04e950..d122ebbe5980 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -2086,6 +2086,7 @@ static int inet_netconf_get_devconf(struct sk_buff *in_skb,
 static int inet_netconf_dump_devconf(struct sk_buff *skb,
 				     struct netlink_callback *cb)
 {
+	const struct nlmsghdr *nlh = cb->nlh;
 	struct net *net = sock_net(skb->sk);
 	int h, s_h;
 	int idx, s_idx;
@@ -2093,6 +2094,21 @@ static int inet_netconf_dump_devconf(struct sk_buff *skb,
 	struct in_device *in_dev;
 	struct hlist_head *head;
 
+	if (cb->strict_check) {
+		struct netlink_ext_ack *extack = cb->extack;
+		struct netconfmsg *ncm;
+
+		if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*ncm))) {
+			NL_SET_ERR_MSG(extack, "ipv4: Invalid header for netconf dump request");
+			return -EINVAL;
+		}
+
+		if (nlmsg_attrlen(nlh, sizeof(*ncm))) {
+			NL_SET_ERR_MSG(extack, "ipv4: Invalid data after header in netconf dump request");
+			return -EINVAL;
+		}
+	}
+
 	s_h = cb->args[0];
 	s_idx = idx = cb->args[1];
 
@@ -2112,7 +2128,7 @@ static int inet_netconf_dump_devconf(struct sk_buff *skb,
 			if (inet_netconf_fill_devconf(skb, dev->ifindex,
 						      &in_dev->cnf,
 						      NETLINK_CB(cb->skb).portid,
-						      cb->nlh->nlmsg_seq,
+						      nlh->nlmsg_seq,
 						      RTM_NEWNETCONF,
 						      NLM_F_MULTI,
 						      NETCONFA_ALL) < 0) {
@@ -2129,7 +2145,7 @@ static int inet_netconf_dump_devconf(struct sk_buff *skb,
 		if (inet_netconf_fill_devconf(skb, NETCONFA_IFINDEX_ALL,
 					      net->ipv4.devconf_all,
 					      NETLINK_CB(cb->skb).portid,
-					      cb->nlh->nlmsg_seq,
+					      nlh->nlmsg_seq,
 					      RTM_NEWNETCONF, NLM_F_MULTI,
 					      NETCONFA_ALL) < 0)
 			goto done;
@@ -2140,7 +2156,7 @@ static int inet_netconf_dump_devconf(struct sk_buff *skb,
 		if (inet_netconf_fill_devconf(skb, NETCONFA_IFINDEX_DEFAULT,
 					      net->ipv4.devconf_dflt,
 					      NETLINK_CB(cb->skb).portid,
-					      cb->nlh->nlmsg_seq,
+					      nlh->nlmsg_seq,
 					      RTM_NEWNETCONF, NLM_F_MULTI,
 					      NETCONFA_ALL) < 0)
 			goto done;
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index ce071d85ad00..2496b12bf721 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -666,6 +666,7 @@ static int inet6_netconf_get_devconf(struct sk_buff *in_skb,
 static int inet6_netconf_dump_devconf(struct sk_buff *skb,
 				      struct netlink_callback *cb)
 {
+	const struct nlmsghdr *nlh = cb->nlh;
 	struct net *net = sock_net(skb->sk);
 	int h, s_h;
 	int idx, s_idx;
@@ -673,6 +674,21 @@ static int inet6_netconf_dump_devconf(struct sk_buff *skb,
 	struct inet6_dev *idev;
 	struct hlist_head *head;
 
+	if (cb->strict_check) {
+		struct netlink_ext_ack *extack = cb->extack;
+		struct netconfmsg *ncm;
+
+		if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*ncm))) {
+			NL_SET_ERR_MSG_MOD(extack, "Invalid header for netconf dump request");
+			return -EINVAL;
+		}
+
+		if (nlmsg_attrlen(nlh, sizeof(*ncm))) {
+			NL_SET_ERR_MSG_MOD(extack, "Invalid data after header in netconf dump request");
+			return -EINVAL;
+		}
+	}
+
 	s_h = cb->args[0];
 	s_idx = idx = cb->args[1];
 
@@ -692,7 +708,7 @@ static int inet6_netconf_dump_devconf(struct sk_buff *skb,
 			if (inet6_netconf_fill_devconf(skb, dev->ifindex,
 						       &idev->cnf,
 						       NETLINK_CB(cb->skb).portid,
-						       cb->nlh->nlmsg_seq,
+						       nlh->nlmsg_seq,
 						       RTM_NEWNETCONF,
 						       NLM_F_MULTI,
 						       NETCONFA_ALL) < 0) {
@@ -709,7 +725,7 @@ static int inet6_netconf_dump_devconf(struct sk_buff *skb,
 		if (inet6_netconf_fill_devconf(skb, NETCONFA_IFINDEX_ALL,
 					       net->ipv6.devconf_all,
 					       NETLINK_CB(cb->skb).portid,
-					       cb->nlh->nlmsg_seq,
+					       nlh->nlmsg_seq,
 					       RTM_NEWNETCONF, NLM_F_MULTI,
 					       NETCONFA_ALL) < 0)
 			goto done;
@@ -720,7 +736,7 @@ static int inet6_netconf_dump_devconf(struct sk_buff *skb,
 		if (inet6_netconf_fill_devconf(skb, NETCONFA_IFINDEX_DEFAULT,
 					       net->ipv6.devconf_dflt,
 					       NETLINK_CB(cb->skb).portid,
-					       cb->nlh->nlmsg_seq,
+					       nlh->nlmsg_seq,
 					       RTM_NEWNETCONF, NLM_F_MULTI,
 					       NETCONFA_ALL) < 0)
 			goto done;
diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c
index 0458c8aa5c11..7f891ffffc05 100644
--- a/net/mpls/af_mpls.c
+++ b/net/mpls/af_mpls.c
@@ -1263,6 +1263,7 @@ static int mpls_netconf_get_devconf(struct sk_buff *in_skb,
 static int mpls_netconf_dump_devconf(struct sk_buff *skb,
 				     struct netlink_callback *cb)
 {
+	const struct nlmsghdr *nlh = cb->nlh;
 	struct net *net = sock_net(skb->sk);
 	struct hlist_head *head;
 	struct net_device *dev;
@@ -1270,6 +1271,21 @@ static int mpls_netconf_dump_devconf(struct sk_buff *skb,
 	int idx, s_idx;
 	int h, s_h;
 
+	if (cb->strict_check) {
+		struct netlink_ext_ack *extack = cb->extack;
+		struct netconfmsg *ncm;
+
+		if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*ncm))) {
+			NL_SET_ERR_MSG_MOD(extack, "Invalid header for netconf dump request");
+			return -EINVAL;
+		}
+
+		if (nlmsg_attrlen(nlh, sizeof(*ncm))) {
+			NL_SET_ERR_MSG_MOD(extack, "Invalid data after header in netconf dump request");
+			return -EINVAL;
+		}
+	}
+
 	s_h = cb->args[0];
 	s_idx = idx = cb->args[1];
 
@@ -1286,7 +1302,7 @@ static int mpls_netconf_dump_devconf(struct sk_buff *skb,
 				goto cont;
 			if (mpls_netconf_fill_devconf(skb, mdev,
 						      NETLINK_CB(cb->skb).portid,
-						      cb->nlh->nlmsg_seq,
+						      nlh->nlmsg_seq,
 						      RTM_NEWNETCONF,
 						      NLM_F_MULTI,
 						      NETCONFA_ALL) < 0) {
-- 
2.11.0