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0117cfabe3
If this module can't load, it is almost certainly because something else is already bound to that SAP. So in that case, return the same error code as other SAP usage, and fail the module load. Also fixes a compiler warning about printk of non const. Signed-off-by: Stephen Hemminger <shemminger@vyatta.com> Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
168 lines
3.4 KiB
C
168 lines
3.4 KiB
C
/*
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* SNAP data link layer. Derived from 802.2
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*
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* Alan Cox <alan@lxorguk.ukuu.org.uk>,
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* from the 802.2 layer by Greg Page.
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* Merged in additions from Greg Page's psnap.c.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/module.h>
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#include <linux/netdevice.h>
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#include <linux/skbuff.h>
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#include <net/datalink.h>
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#include <net/llc.h>
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#include <net/psnap.h>
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#include <linux/mm.h>
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#include <linux/in.h>
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#include <linux/init.h>
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#include <linux/rculist.h>
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static LIST_HEAD(snap_list);
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static DEFINE_SPINLOCK(snap_lock);
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static struct llc_sap *snap_sap;
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/*
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* Find a snap client by matching the 5 bytes.
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*/
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static struct datalink_proto *find_snap_client(unsigned char *desc)
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{
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struct datalink_proto *proto = NULL, *p;
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list_for_each_entry_rcu(p, &snap_list, node) {
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if (!memcmp(p->type, desc, 5)) {
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proto = p;
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break;
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}
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}
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return proto;
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}
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/*
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* A SNAP packet has arrived
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*/
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static int snap_rcv(struct sk_buff *skb, struct net_device *dev,
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struct packet_type *pt, struct net_device *orig_dev)
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{
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int rc = 1;
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struct datalink_proto *proto;
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static struct packet_type snap_packet_type = {
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.type = cpu_to_be16(ETH_P_SNAP),
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};
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if (unlikely(!pskb_may_pull(skb, 5)))
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goto drop;
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rcu_read_lock();
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proto = find_snap_client(skb_transport_header(skb));
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if (proto) {
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/* Pass the frame on. */
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skb->transport_header += 5;
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skb_pull_rcsum(skb, 5);
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rc = proto->rcvfunc(skb, dev, &snap_packet_type, orig_dev);
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}
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rcu_read_unlock();
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if (unlikely(!proto))
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goto drop;
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out:
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return rc;
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drop:
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kfree_skb(skb);
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goto out;
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}
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/*
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* Put a SNAP header on a frame and pass to 802.2
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*/
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static int snap_request(struct datalink_proto *dl,
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struct sk_buff *skb, u8 *dest)
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{
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memcpy(skb_push(skb, 5), dl->type, 5);
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llc_build_and_send_ui_pkt(snap_sap, skb, dest, snap_sap->laddr.lsap);
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return 0;
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}
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/*
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* Set up the SNAP layer
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*/
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EXPORT_SYMBOL(register_snap_client);
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EXPORT_SYMBOL(unregister_snap_client);
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static const char snap_err_msg[] __initconst =
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KERN_CRIT "SNAP - unable to register with 802.2\n";
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static int __init snap_init(void)
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{
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snap_sap = llc_sap_open(0xAA, snap_rcv);
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if (!snap_sap) {
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printk(snap_err_msg);
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return -EBUSY;
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}
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return 0;
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}
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module_init(snap_init);
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static void __exit snap_exit(void)
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{
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llc_sap_put(snap_sap);
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}
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module_exit(snap_exit);
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/*
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* Register SNAP clients. We don't yet use this for IP.
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*/
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struct datalink_proto *register_snap_client(unsigned char *desc,
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int (*rcvfunc)(struct sk_buff *,
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struct net_device *,
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struct packet_type *,
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struct net_device *))
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{
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struct datalink_proto *proto = NULL;
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spin_lock_bh(&snap_lock);
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if (find_snap_client(desc))
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goto out;
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proto = kmalloc(sizeof(*proto), GFP_ATOMIC);
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if (proto) {
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memcpy(proto->type, desc,5);
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proto->rcvfunc = rcvfunc;
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proto->header_length = 5 + 3; /* snap + 802.2 */
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proto->request = snap_request;
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list_add_rcu(&proto->node, &snap_list);
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}
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out:
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spin_unlock_bh(&snap_lock);
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synchronize_net();
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return proto;
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}
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/*
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* Unregister SNAP clients. Protocols no longer want to play with us ...
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*/
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void unregister_snap_client(struct datalink_proto *proto)
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{
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spin_lock_bh(&snap_lock);
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list_del_rcu(&proto->node);
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spin_unlock_bh(&snap_lock);
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synchronize_net();
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kfree(proto);
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}
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MODULE_LICENSE("GPL");
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