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>

1 files changed, 4 insertions, 3 deletions

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 12f2f725a945..d711ecbbb9d3 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1584,7 +1584,7 @@ static int packet_sendmsg_spkt(struct kiocb *iocb, struct socket *sock,
                                struct msghdr *msg, size_t len)
 {
         struct sock *sk = sock->sk;
-        struct sockaddr_pkt *saddr = (struct sockaddr_pkt *)msg->msg_name;
+        DECLARE_SOCKADDR(struct sockaddr_pkt *, saddr, msg->msg_name);
         struct sk_buff *skb = NULL;
         struct net_device *dev;
         __be16 proto = 0;
@@ -2196,7 +2196,7 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)
         __be16 proto;
         int err, reserve = 0;
         void *ph;
-        struct sockaddr_ll *saddr = (struct sockaddr_ll *)msg->msg_name;
+        DECLARE_SOCKADDR(struct sockaddr_ll *, saddr, msg->msg_name);
         bool need_wait = !(msg->msg_flags & MSG_DONTWAIT);
         int tp_len, size_max;
         unsigned char *addr;
@@ -2346,7 +2346,7 @@ static struct sk_buff *packet_alloc_skb(struct sock *sk, size_t prepad,
 static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len)
 {
         struct sock *sk = sock->sk;
-        struct sockaddr_ll *saddr = (struct sockaddr_ll *)msg->msg_name;
+        DECLARE_SOCKADDR(struct sockaddr_ll *, saddr, msg->msg_name);
         struct sk_buff *skb;
         struct net_device *dev;
         __be16 proto;
@@ -2922,6 +2922,7 @@ static int packet_recvmsg(struct kiocb *iocb, struct socket *sock,
                  * in, we fill it in now.
                  */
                 if (sock->type == SOCK_PACKET) {
+                        __sockaddr_check_size(sizeof(struct sockaddr_pkt));
                         msg->msg_namelen = sizeof(struct sockaddr_pkt);
                 } else {
                         struct sockaddr_ll *sll = &PACKET_SKB_CB(skb)->sa.ll;