[NETLINK]: Introduce nlmsg_hdr() helper

For the common "(struct nlmsghdr *)skb->data" sequence, so that we reduce the
number of direct accesses to skb->data and for consistency with all the other
cast skb member helpers.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/connector/connector.c

@@ -212,7 +212,7 @@ static void cn_rx_skb(struct sk_buff *__skb)
 	skb = skb_get(__skb);
 
 	if (skb->len >= NLMSG_SPACE(0)) {
-		nlh = (struct nlmsghdr *)skb->data;
+		nlh = nlmsg_hdr(skb);
 
 		if (nlh->nlmsg_len < sizeof(struct cn_msg) ||
 		    skb->len < nlh->nlmsg_len ||

drivers/scsi/scsi_netlink.c

@@ -50,7 +50,7 @@ scsi_nl_rcv_msg(struct sk_buff *skb)
 	while (skb->len >= NLMSG_SPACE(0)) {
 		err = 0;
 
-		nlh = (struct nlmsghdr *) skb->data;
+		nlh = nlmsg_hdr(skb);
 		if ((nlh->nlmsg_len < (sizeof(*nlh) + sizeof(*hdr))) ||
 		    (skb->len < nlh->nlmsg_len)) {
 			printk(KERN_WARNING "%s: discarding partial skb\n",

drivers/scsi/scsi_transport_iscsi.c

@@ -1081,7 +1081,7 @@ iscsi_if_rx(struct sock *sk, int len)
 			struct nlmsghdr	*nlh;
 			struct iscsi_uevent *ev;
 
-			nlh = (struct nlmsghdr *)skb->data;
+			nlh = nlmsg_hdr(skb);
 			if (nlh->nlmsg_len < sizeof(*nlh) ||
 			    skb->len < nlh->nlmsg_len) {
 				break;

fs/ecryptfs/netlink.c

@@ -97,7 +97,7 @@ out:
  */
 static int ecryptfs_process_nl_response(struct sk_buff *skb)
 {
-	struct nlmsghdr *nlh = (struct nlmsghdr*)skb->data;
+	struct nlmsghdr *nlh = nlmsg_hdr(skb);
 	struct ecryptfs_message *msg = NLMSG_DATA(nlh);
 	int rc;
 
@@ -181,7 +181,7 @@ receive:
 				"rc = [%d]\n", rc);
 		return;
 	}
-	nlh = (struct nlmsghdr *)skb->data;
+	nlh = nlmsg_hdr(skb);
 	if (!NLMSG_OK(nlh, skb->len)) {
 		ecryptfs_printk(KERN_ERR, "Received corrupt netlink "
 				"message\n");

include/linux/netlink.h

@@ -138,6 +138,11 @@ struct nlattr
 #include <linux/capability.h>
 #include <linux/skbuff.h>
 
+static inline struct nlmsghdr *nlmsg_hdr(const struct sk_buff *skb)
+{
+	return (struct nlmsghdr *)skb->data;
+}
+
 struct netlink_skb_parms
 {
 	struct ucred		creds;		/* Skb credentials	*/

kernel/audit.c

@@ -151,7 +151,7 @@ struct audit_buffer {
 
 static void audit_set_pid(struct audit_buffer *ab, pid_t pid)
 {
-	struct nlmsghdr *nlh = (struct nlmsghdr *)ab->skb->data;
+	struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
 	nlh->nlmsg_pid = pid;
 }
 
@@ -750,7 +750,7 @@ static void audit_receive_skb(struct sk_buff *skb)
 	u32		rlen;
 
 	while (skb->len >= NLMSG_SPACE(0)) {
-		nlh = (struct nlmsghdr *)skb->data;
+		nlh = nlmsg_hdr(skb);
 		if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len)
 			return;
 		rlen = NLMSG_ALIGN(nlh->nlmsg_len);
@@ -1268,7 +1268,7 @@ void audit_log_end(struct audit_buffer *ab)
 		audit_log_lost("rate limit exceeded");
 	} else {
 		if (audit_pid) {
-			struct nlmsghdr *nlh = (struct nlmsghdr *)ab->skb->data;
+			struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
 			nlh->nlmsg_len = ab->skb->len - NLMSG_SPACE(0);
 			skb_queue_tail(&audit_skb_queue, ab->skb);
 			ab->skb = NULL;

kernel/taskstats.c

@@ -102,7 +102,7 @@ static int prepare_reply(struct genl_info *info, u8 cmd, struct sk_buff **skbp,
  */
 static int send_reply(struct sk_buff *skb, pid_t pid)
 {
-	struct genlmsghdr *genlhdr = nlmsg_data((struct nlmsghdr *)skb->data);
+	struct genlmsghdr *genlhdr = nlmsg_data(nlmsg_hdr(skb));
 	void *reply = genlmsg_data(genlhdr);
 	int rc;
 
@@ -121,7 +121,7 @@ static int send_reply(struct sk_buff *skb, pid_t pid)
 static void send_cpu_listeners(struct sk_buff *skb,
 					struct listener_list *listeners)
 {
-	struct genlmsghdr *genlhdr = nlmsg_data((struct nlmsghdr *)skb->data);
+	struct genlmsghdr *genlhdr = nlmsg_data(nlmsg_hdr(skb));
 	struct listener *s, *tmp;
 	struct sk_buff *skb_next, *skb_cur = skb;
 	void *reply = genlmsg_data(genlhdr);

net/decnet/netfilter/dn_rtmsg.c

@@ -102,7 +102,7 @@ static unsigned int dnrmg_hook(unsigned int hook,
 
 static inline void dnrmg_receive_user_skb(struct sk_buff *skb)
 {
-	struct nlmsghdr *nlh = (struct nlmsghdr *)skb->data;
+	struct nlmsghdr *nlh = nlmsg_hdr(skb);
 
 	if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len)
 		return;

net/ipv4/fib_frontend.c

@@ -807,7 +807,7 @@ static void nl_fib_input(struct sock *sk, int len)
 	if (skb == NULL)
 		return;
 
-	nlh = (struct nlmsghdr *)skb->data;
+	nlh = nlmsg_hdr(skb);
 	if (skb->len < NLMSG_SPACE(0) || skb->len < nlh->nlmsg_len ||
 	    nlh->nlmsg_len < NLMSG_LENGTH(sizeof(*frn))) {
 		kfree_skb(skb);

net/ipv4/inet_diag.c

@@ -847,7 +847,7 @@ static inline void inet_diag_rcv_skb(struct sk_buff *skb)
 {
 	if (skb->len >= NLMSG_SPACE(0)) {
 		int err;
-		struct nlmsghdr *nlh = (struct nlmsghdr *)skb->data;
+		struct nlmsghdr *nlh = nlmsg_hdr(skb);
 
 		if (nlh->nlmsg_len < sizeof(*nlh) ||
 		    skb->len < nlh->nlmsg_len)

net/ipv4/netfilter/ip_queue.c

@@ -497,7 +497,7 @@ ipq_rcv_skb(struct sk_buff *skb)
 	if (skblen < sizeof(*nlh))
 		return;
 
-	nlh = (struct nlmsghdr *)skb->data;
+	nlh = nlmsg_hdr(skb);
 	nlmsglen = nlh->nlmsg_len;
 	if (nlmsglen < sizeof(*nlh) || skblen < nlmsglen)
 		return;

net/ipv6/netfilter/ip6_queue.c

@@ -487,7 +487,7 @@ ipq_rcv_skb(struct sk_buff *skb)
 	if (skblen < sizeof(*nlh))
 		return;
 
-	nlh = (struct nlmsghdr *)skb->data;
+	nlh = nlmsg_hdr(skb);
 	nlmsglen = nlh->nlmsg_len;
 	if (nlmsglen < sizeof(*nlh) || skblen < nlmsglen)
 		return;

net/netlink/af_netlink.c

@@ -1471,7 +1471,7 @@ static int netlink_rcv_skb(struct sk_buff *skb, int (*cb)(struct sk_buff *,
 	int err;
 
 	while (skb->len >= nlmsg_total_size(0)) {
-		nlh = (struct nlmsghdr *) skb->data;
+		nlh = nlmsg_hdr(skb);
 
 		if (nlh->nlmsg_len < NLMSG_HDRLEN || skb->len < nlh->nlmsg_len)
 			return 0;

net/tipc/netlink.c

@@ -57,7 +57,7 @@ static int handle_cmd(struct sk_buff *skb, struct genl_info *info)
 
 	if (rep_buf) {
 		skb_push(rep_buf, hdr_space);
-		rep_nlh = (struct nlmsghdr *)rep_buf->data;
+		rep_nlh = nlmsg_hdr(rep_buf);
 		memcpy(rep_nlh, req_nlh, hdr_space);
 		rep_nlh->nlmsg_len = rep_buf->len;
 		genlmsg_unicast(rep_buf, req_nlh->nlmsg_pid);

security/selinux/hooks.c

@@ -3786,7 +3786,7 @@ static int selinux_nlmsg_perm(struct sock *sk, struct sk_buff *skb)
 		err = -EINVAL;
 		goto out;
 	}
-	nlh = (struct nlmsghdr *)skb->data;
+	nlh = nlmsg_hdr(skb);
 	
 	err = selinux_nlmsg_lookup(isec->sclass, nlh->nlmsg_type, &perm);
 	if (err) {