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, 7 insertions, 11 deletions

diff --git a/net/ipv6/datagram.c b/net/ipv6/datagram.c
index 6983058942ea..bce73cbd203a 100644
--- a/net/ipv6/datagram.c
+++ b/net/ipv6/datagram.c
@@ -322,7 +322,7 @@ int ipv6_recv_error(struct sock *sk, struct msghdr *msg, int len, int *addr_len)
         struct ipv6_pinfo *np = inet6_sk(sk);
         struct sock_exterr_skb *serr;
         struct sk_buff *skb, *skb2;
-        struct sockaddr_in6 *sin;
+        DECLARE_SOCKADDR(struct sockaddr_in6 *, sin, msg->msg_name);
         struct {
                 struct sock_extended_err ee;
                 struct sockaddr_in6      offender;
@@ -348,7 +348,6 @@ int ipv6_recv_error(struct sock *sk, struct msghdr *msg, int len, int *addr_len)
 
         serr = SKB_EXT_ERR(skb);
 
-        sin = (struct sockaddr_in6 *)msg->msg_name;
         if (sin) {
                 const unsigned char *nh = skb_network_header(skb);
                 sin->sin6_family = AF_INET6;
@@ -429,8 +428,8 @@ int ipv6_recv_rxpmtu(struct sock *sk, struct msghdr *msg, int len,
 {
         struct ipv6_pinfo *np = inet6_sk(sk);
         struct sk_buff *skb;
-        struct sockaddr_in6 *sin;
         struct ip6_mtuinfo mtu_info;
+        DECLARE_SOCKADDR(struct sockaddr_in6 *, sin, msg->msg_name);
         int err;
         int copied;
 
@@ -452,7 +451,6 @@ int ipv6_recv_rxpmtu(struct sock *sk, struct msghdr *msg, int len,
 
         memcpy(&mtu_info, IP6CBMTU(skb), sizeof(mtu_info));
 
-        sin = (struct sockaddr_in6 *)msg->msg_name;
         if (sin) {
                 sin->sin6_family = AF_INET6;
                 sin->sin6_flowinfo = 0;
diff --git a/net/ipv6/ping.c b/net/ipv6/ping.c
index 15d23b8c2129..cd71f3a540be 100644
--- a/net/ipv6/ping.c
+++ b/net/ipv6/ping.c
@@ -103,7 +103,7 @@ int ping_v6_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
                 return err;
 
         if (msg->msg_name) {
-                struct sockaddr_in6 *u = (struct sockaddr_in6 *) msg->msg_name;
+                DECLARE_SOCKADDR(struct sockaddr_in6 *, u, msg->msg_name);
                 if (msg->msg_namelen < sizeof(struct sockaddr_in6) ||
                     u->sin6_family != AF_INET6) {
                         return -EINVAL;
diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c
index 5f10b7ea7ccc..b4523117aeae 100644
--- a/net/ipv6/raw.c
+++ b/net/ipv6/raw.c
@@ -457,7 +457,7 @@ static int rawv6_recvmsg(struct kiocb *iocb, struct sock *sk,
                   int noblock, int flags, int *addr_len)
 {
         struct ipv6_pinfo *np = inet6_sk(sk);
-        struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)msg->msg_name;
+        DECLARE_SOCKADDR(struct sockaddr_in6 *, sin6, msg->msg_name);
         struct sk_buff *skb;
         size_t copied;
         int err;
@@ -734,7 +734,7 @@ static int rawv6_sendmsg(struct kiocb *iocb, struct sock *sk,
                    struct msghdr *msg, size_t len)
 {
         struct ipv6_txoptions opt_space;
-        struct sockaddr_in6 * sin6 = (struct sockaddr_in6 *) msg->msg_name;
+        DECLARE_SOCKADDR(struct sockaddr_in6 *, sin6, msg->msg_name);
         struct in6_addr *daddr, *final_p, final;
         struct inet_sock *inet = inet_sk(sk);
         struct ipv6_pinfo *np = inet6_sk(sk);
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index fa9d988f4012..233c3ab6aee4 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -460,9 +460,7 @@ try_again:
 
         /* Copy the address. */
         if (msg->msg_name) {
-                struct sockaddr_in6 *sin6;
-
-                sin6 = (struct sockaddr_in6 *) msg->msg_name;
+                DECLARE_SOCKADDR(struct sockaddr_in6 *, sin6, msg->msg_name);
                 sin6->sin6_family = AF_INET6;
                 sin6->sin6_port = udp_hdr(skb)->source;
                 sin6->sin6_flowinfo = 0;
@@ -1041,7 +1039,7 @@ int udpv6_sendmsg(struct kiocb *iocb, struct sock *sk,
         struct udp_sock *up = udp_sk(sk);
         struct inet_sock *inet = inet_sk(sk);
         struct ipv6_pinfo *np = inet6_sk(sk);
-        struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *) msg->msg_name;
+        DECLARE_SOCKADDR(struct sockaddr_in6 *, sin6, msg->msg_name);
         struct in6_addr *daddr, *final_p, final;
         struct ipv6_txoptions *opt = NULL;
         struct ip6_flowlabel *flowlabel = NULL;