net: Make setsockopt() optlen be unsigned.

This provides safety against negative optlen at the type
level instead of depending upon (sometimes non-trivial)
checks against this sprinkled all over the the place, in
each and every implementation.

Based upon work done by Arjan van de Ven and feedback
from Linus Torvalds.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/sock.c b/net/core/sock.c
index 524712a..77fbfed 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -446,7 +446,7 @@
  */
 
 int sock_setsockopt(struct socket *sock, int level, int optname,
-		    char __user *optval, int optlen)
+		    char __user *optval, unsigned int optlen)
 {
 	struct sock *sk = sock->sk;
 	int val;
@@ -1697,7 +1697,7 @@
 EXPORT_SYMBOL(sock_no_shutdown);
 
 int sock_no_setsockopt(struct socket *sock, int level, int optname,
-		    char __user *optval, int optlen)
+		    char __user *optval, unsigned int optlen)
 {
 	return -EOPNOTSUPP;
 }
@@ -2018,7 +2018,7 @@
  *	Set socket options on an inet socket.
  */
 int sock_common_setsockopt(struct socket *sock, int level, int optname,
-			   char __user *optval, int optlen)
+			   char __user *optval, unsigned int optlen)
 {
 	struct sock *sk = sock->sk;
 
@@ -2028,7 +2028,7 @@
 
 #ifdef CONFIG_COMPAT
 int compat_sock_common_setsockopt(struct socket *sock, int level, int optname,
-				  char __user *optval, int optlen)
+				  char __user *optval, unsigned int optlen)
 {
 	struct sock *sk = sock->sk;