Subject: [PATCH net-next 19/20] net: Update netconf dump handlers for strict data checking

From: David Ahern <[email-masked]>
Date: Thu, 4 Oct 2018 14:33:54 -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 af968d4fe4fc..595706d6b672 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -2069,6 +2069,7 @@ 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;
@@ -2076,6 +2077,21 @@ 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, "Invalid header");
+			return -EINVAL;
+		}
+
+		if (nlh->nlmsg_len != nlmsg_msg_size(sizeof(*ncm))) {
+			NL_SET_ERR_MSG(extack, "Invalid data after header");
+			return -EINVAL;
+		}
+	}
+
 	s_h = cb->args[0];
 	s_idx = idx = cb->args[1];
 
@@ -2095,7 +2111,7 @@ 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) {
@@ -2112,7 +2128,7 @@ 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;
@@ -2123,7 +2139,7 @@ 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 693199a29426..9dfe6c2106c1 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(extack, "Invalid header");
+			return -EINVAL;
+		}
+
+		if (nlh->nlmsg_len != nlmsg_msg_size(sizeof(*ncm))) {
+			NL_SET_ERR_MSG(extack, "Invalid data after header");
+			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 3e33934751b4..b80b00b55bdf 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(extack, "Invalid header");
+			return -EINVAL;
+		}
+
+		if (nlh->nlmsg_len != nlmsg_msg_size(sizeof(*ncm))) {
+			NL_SET_ERR_MSG(extack, "Invalid data after header");
+			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