net: add build-time checks for msg->msg_name size

This is a follow-up patch to f3d3342602f8bc ("net: rework recvmsg
handler msg_name and msg_namelen logic").

DECLARE_SOCKADDR validates that the structure we use for writing the
name information to is not larger than the buffer which is reserved
for msg->msg_name (which is 128 bytes). Also use DECLARE_SOCKADDR
consistently in sendmsg code paths.

Signed-off-by: Steffen Hurrle <steffen@hurrle.net>
Suggested-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 8 insertions, 10 deletions

diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index a9fc435..22f15eb 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -390,7 +390,7 @@ int ip_recv_error(struct sock *sk, struct msghdr *msg, int len, int *addr_len)
 {
 	struct sock_exterr_skb *serr;
 	struct sk_buff *skb, *skb2;
-	struct sockaddr_in *sin;
+	DECLARE_SOCKADDR(struct sockaddr_in *, sin, msg->msg_name);
 	struct {
 		struct sock_extended_err ee;
 		struct sockaddr_in	 offender;
@@ -416,7 +416,6 @@ int ip_recv_error(struct sock *sk, struct msghdr *msg, int len, int *addr_len)
 
 	serr = SKB_EXT_ERR(skb);
 
-	sin = (struct sockaddr_in *)msg->msg_name;
 	if (sin) {
 		sin->sin_family = AF_INET;
 		sin->sin_addr.s_addr = *(__be32 *)(skb_network_header(skb) +
diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index cae5262..e09e883 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -700,7 +700,7 @@ static int ping_v4_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *m
 	 */
 
 	if (msg->msg_name) {
-		struct sockaddr_in *usin = (struct sockaddr_in *)msg->msg_name;
+		DECLARE_SOCKADDR(struct sockaddr_in *, usin, msg->msg_name);
 		if (msg->msg_namelen < sizeof(*usin))
 			return -EINVAL;
 		if (usin->sin_family != AF_INET)
@@ -873,7 +873,7 @@ int ping_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 
 	/* Copy the address and add cmsg data. */
 	if (family == AF_INET) {
-		struct sockaddr_in *sin = (struct sockaddr_in *)msg->msg_name;
+		DECLARE_SOCKADDR(struct sockaddr_in *, sin, msg->msg_name);
 
 		if (sin) {
 			sin->sin_family = AF_INET;
@@ -890,8 +890,7 @@ int ping_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 	} else if (family == AF_INET6) {
 		struct ipv6_pinfo *np = inet6_sk(sk);
 		struct ipv6hdr *ip6 = ipv6_hdr(skb);
-		struct sockaddr_in6 *sin6 =
-			(struct sockaddr_in6 *)msg->msg_name;
+		DECLARE_SOCKADDR(struct sockaddr_in6 *, sin6, msg->msg_name);
 
 		if (sin6) {
 			sin6->sin6_family = AF_INET6;
diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index 81e6cfd..c04518f 100644
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -493,7 +493,7 @@ static int raw_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 	 */
 
 	if (msg->msg_namelen) {
-		struct sockaddr_in *usin = (struct sockaddr_in *)msg->msg_name;
+		DECLARE_SOCKADDR(struct sockaddr_in *, usin, msg->msg_name);
 		err = -EINVAL;
 		if (msg->msg_namelen < sizeof(*usin))
 			goto out;
@@ -690,7 +690,7 @@ static int raw_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 	struct inet_sock *inet = inet_sk(sk);
 	size_t copied = 0;
 	int err = -EOPNOTSUPP;
-	struct sockaddr_in *sin = (struct sockaddr_in *)msg->msg_name;
+	DECLARE_SOCKADDR(struct sockaddr_in *, sin, msg->msg_name);
 	struct sk_buff *skb;
 
 	if (flags & MSG_OOB)
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 3d3141f..77bd16f 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -902,7 +902,7 @@ int udp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 	 *	Get and verify the address.
 	 */
 	if (msg->msg_name) {
-		struct sockaddr_in *usin = (struct sockaddr_in *)msg->msg_name;
+		DECLARE_SOCKADDR(struct sockaddr_in *, usin, msg->msg_name);
 		if (msg->msg_namelen < sizeof(*usin))
 			return -EINVAL;
 		if (usin->sin_family != AF_INET) {
@@ -1226,7 +1226,7 @@ int udp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 		size_t len, int noblock, int flags, int *addr_len)
 {
 	struct inet_sock *inet = inet_sk(sk);
-	struct sockaddr_in *sin = (struct sockaddr_in *)msg->msg_name;
+	DECLARE_SOCKADDR(struct sockaddr_in *, sin, msg->msg_name);
 	struct sk_buff *skb;
 	unsigned int ulen, copied;
 	int peeked, off = 0;