ipv4: process socket-level control messages in IPv4

Process socket-level control messages by invoking
__sock_cmsg_send in ip_cmsg_send for control messages on
the SOL_SOCKET layer.

This makes sure whenever ip_cmsg_send is called in udp, icmp,
and raw, we also process socket-level control messages.

Note that this commit interprets new control messages that
were ignored before. As such, this commit does not change
the behavior of IPv4 control messages.

Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/ip.h

@@ -56,6 +56,7 @@ static inline unsigned int ip_hdrlen(const struct sk_buff *skb)
 }
 
 struct ipcm_cookie {
+	struct sockcm_cookie	sockc;
 	__be32			addr;
 	int			oif;
 	struct ip_options_rcu	*opt;
@@ -550,7 +551,7 @@ int ip_options_rcv_srr(struct sk_buff *skb);
 
 void ipv4_pktinfo_prepare(const struct sock *sk, struct sk_buff *skb);
 void ip_cmsg_recv_offset(struct msghdr *msg, struct sk_buff *skb, int offset);
-int ip_cmsg_send(struct net *net, struct msghdr *msg,
+int ip_cmsg_send(struct sock *sk, struct msghdr *msg,
 		 struct ipcm_cookie *ipc, bool allow_ipv6);
 int ip_setsockopt(struct sock *sk, int level, int optname, char __user *optval,
 		  unsigned int optlen);

net/ipv4/ip_sockglue.c

@@ -219,11 +219,12 @@ void ip_cmsg_recv_offset(struct msghdr *msg, struct sk_buff *skb,
 }
 EXPORT_SYMBOL(ip_cmsg_recv_offset);
 
-int ip_cmsg_send(struct net *net, struct msghdr *msg, struct ipcm_cookie *ipc,
+int ip_cmsg_send(struct sock *sk, struct msghdr *msg, struct ipcm_cookie *ipc,
 		 bool allow_ipv6)
 {
 	int err, val;
 	struct cmsghdr *cmsg;
+	struct net *net = sock_net(sk);
 
 	for_each_cmsghdr(cmsg, msg) {
 		if (!CMSG_OK(msg, cmsg))
@@ -244,6 +245,12 @@ int ip_cmsg_send(struct net *net, struct msghdr *msg, struct ipcm_cookie *ipc,
 			continue;
 		}
 #endif
+		if (cmsg->cmsg_level == SOL_SOCKET) {
+			if (__sock_cmsg_send(sk, msg, cmsg, &ipc->sockc))
+				return -EINVAL;
+			continue;
+		}
+
 		if (cmsg->cmsg_level != SOL_IP)
 			continue;
 		switch (cmsg->cmsg_type) {

net/ipv4/ping.c

@@ -747,7 +747,7 @@ static int ping_v4_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 	sock_tx_timestamp(sk, &ipc.tx_flags);
 
 	if (msg->msg_controllen) {
-		err = ip_cmsg_send(sock_net(sk), msg, &ipc, false);
+		err = ip_cmsg_send(sk, msg, &ipc, false);
 		if (unlikely(err)) {
 			kfree(ipc.opt);
 			return err;

net/ipv4/raw.c

@@ -548,7 +548,7 @@ static int raw_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 	ipc.oif = sk->sk_bound_dev_if;
 
 	if (msg->msg_controllen) {
-		err = ip_cmsg_send(net, msg, &ipc, false);
+		err = ip_cmsg_send(sk, msg, &ipc, false);
 		if (unlikely(err)) {
 			kfree(ipc.opt);
 			goto out;

net/ipv4/udp.c

@@ -1034,8 +1034,7 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 	sock_tx_timestamp(sk, &ipc.tx_flags);
 
 	if (msg->msg_controllen) {
-		err = ip_cmsg_send(sock_net(sk), msg, &ipc,
-				   sk->sk_family == AF_INET6);
+		err = ip_cmsg_send(sk, msg, &ipc, sk->sk_family == AF_INET6);
 		if (unlikely(err)) {
 			kfree(ipc.opt);
 			return err;