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/ipv4/raw.c b/net/ipv4/raw.c
index ebb1e58..757c917 100644
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -741,7 +741,7 @@
 }
 
 static int do_raw_setsockopt(struct sock *sk, int level, int optname,
-			  char __user *optval, int optlen)
+			  char __user *optval, unsigned int optlen)
 {
 	if (optname == ICMP_FILTER) {
 		if (inet_sk(sk)->num != IPPROTO_ICMP)
@@ -753,7 +753,7 @@
 }
 
 static int raw_setsockopt(struct sock *sk, int level, int optname,
-			  char __user *optval, int optlen)
+			  char __user *optval, unsigned int optlen)
 {
 	if (level != SOL_RAW)
 		return ip_setsockopt(sk, level, optname, optval, optlen);
@@ -762,7 +762,7 @@
 
 #ifdef CONFIG_COMPAT
 static int compat_raw_setsockopt(struct sock *sk, int level, int optname,
-				 char __user *optval, int optlen)
+				 char __user *optval, unsigned int optlen)
 {
 	if (level != SOL_RAW)
 		return compat_ip_setsockopt(sk, level, optname, optval, optlen);