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610 lines
14 KiB
610 lines
14 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* G8BPQ compatible "AX.25 via ethernet" driver release 004 |
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* |
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* This code REQUIRES 2.0.0 or higher/ NET3.029 |
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* |
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* This is a "pseudo" network driver to allow AX.25 over Ethernet |
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* using G8BPQ encapsulation. It has been extracted from the protocol |
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* implementation because |
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* |
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* - things got unreadable within the protocol stack |
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* - to cure the protocol stack from "feature-ism" |
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* - a protocol implementation shouldn't need to know on |
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* which hardware it is running |
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* - user-level programs like the AX.25 utilities shouldn't |
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* need to know about the hardware. |
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* - IP over ethernet encapsulated AX.25 was impossible |
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* - rxecho.c did not work |
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* - to have room for extensions |
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* - it just deserves to "live" as an own driver |
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* |
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* This driver can use any ethernet destination address, and can be |
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* limited to accept frames from one dedicated ethernet card only. |
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* |
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* Note that the driver sets up the BPQ devices automagically on |
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* startup or (if started before the "insmod" of an ethernet device) |
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* on "ifconfig up". It hopefully will remove the BPQ on "rmmod"ing |
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* the ethernet device (in fact: as soon as another ethernet or bpq |
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* device gets "ifconfig"ured). |
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* |
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* I have heard that several people are thinking of experiments |
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* with highspeed packet radio using existing ethernet cards. |
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* Well, this driver is prepared for this purpose, just add |
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* your tx key control and a txdelay / tailtime algorithm, |
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* probably some buffering, and /voila/... |
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* |
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* History |
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* BPQ 001 Joerg(DL1BKE) Extracted BPQ code from AX.25 |
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* protocol stack and added my own |
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* yet existing patches |
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* BPQ 002 Joerg(DL1BKE) Scan network device list on |
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* startup. |
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* BPQ 003 Joerg(DL1BKE) Ethernet destination address |
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* and accepted source address |
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* can be configured by an ioctl() |
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* call. |
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* Fixed to match Linux networking |
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* changes - 2.1.15. |
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* BPQ 004 Joerg(DL1BKE) Fixed to not lock up on ifconfig. |
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*/ |
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#include <linux/errno.h> |
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#include <linux/types.h> |
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#include <linux/socket.h> |
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#include <linux/in.h> |
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#include <linux/kernel.h> |
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#include <linux/string.h> |
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#include <linux/net.h> |
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#include <linux/slab.h> |
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#include <net/ax25.h> |
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#include <linux/inet.h> |
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#include <linux/netdevice.h> |
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#include <linux/etherdevice.h> |
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#include <linux/if_arp.h> |
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#include <linux/skbuff.h> |
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#include <net/sock.h> |
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#include <linux/uaccess.h> |
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#include <linux/mm.h> |
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#include <linux/interrupt.h> |
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#include <linux/notifier.h> |
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#include <linux/proc_fs.h> |
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#include <linux/seq_file.h> |
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#include <linux/stat.h> |
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#include <linux/module.h> |
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#include <linux/init.h> |
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#include <linux/rtnetlink.h> |
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#include <net/ip.h> |
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#include <net/arp.h> |
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#include <net/net_namespace.h> |
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#include <linux/bpqether.h> |
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static const char banner[] __initconst = KERN_INFO \ |
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"AX.25: bpqether driver version 004\n"; |
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static int bpq_rcv(struct sk_buff *, struct net_device *, struct packet_type *, struct net_device *); |
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static int bpq_device_event(struct notifier_block *, unsigned long, void *); |
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static struct packet_type bpq_packet_type __read_mostly = { |
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.type = cpu_to_be16(ETH_P_BPQ), |
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.func = bpq_rcv, |
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}; |
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static struct notifier_block bpq_dev_notifier = { |
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.notifier_call = bpq_device_event, |
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}; |
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struct bpqdev { |
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struct list_head bpq_list; /* list of bpq devices chain */ |
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struct net_device *ethdev; /* link to ethernet device */ |
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struct net_device *axdev; /* bpq device (bpq#) */ |
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char dest_addr[6]; /* ether destination address */ |
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char acpt_addr[6]; /* accept ether frames from this address only */ |
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}; |
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static LIST_HEAD(bpq_devices); |
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/* |
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* bpqether network devices are paired with ethernet devices below them, so |
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* form a special "super class" of normal ethernet devices; split their locks |
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* off into a separate class since they always nest. |
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*/ |
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static struct lock_class_key bpq_netdev_xmit_lock_key; |
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static struct lock_class_key bpq_netdev_addr_lock_key; |
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static void bpq_set_lockdep_class_one(struct net_device *dev, |
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struct netdev_queue *txq, |
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void *_unused) |
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{ |
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lockdep_set_class(&txq->_xmit_lock, &bpq_netdev_xmit_lock_key); |
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} |
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static void bpq_set_lockdep_class(struct net_device *dev) |
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{ |
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lockdep_set_class(&dev->addr_list_lock, &bpq_netdev_addr_lock_key); |
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netdev_for_each_tx_queue(dev, bpq_set_lockdep_class_one, NULL); |
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} |
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/* ------------------------------------------------------------------------ */ |
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/* |
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* Get the ethernet device for a BPQ device |
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*/ |
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static inline struct net_device *bpq_get_ether_dev(struct net_device *dev) |
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{ |
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struct bpqdev *bpq = netdev_priv(dev); |
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return bpq ? bpq->ethdev : NULL; |
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} |
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/* |
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* Get the BPQ device for the ethernet device |
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*/ |
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static inline struct net_device *bpq_get_ax25_dev(struct net_device *dev) |
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{ |
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struct bpqdev *bpq; |
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list_for_each_entry_rcu(bpq, &bpq_devices, bpq_list, |
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lockdep_rtnl_is_held()) { |
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if (bpq->ethdev == dev) |
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return bpq->axdev; |
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} |
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return NULL; |
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} |
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static inline int dev_is_ethdev(struct net_device *dev) |
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{ |
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return dev->type == ARPHRD_ETHER && strncmp(dev->name, "dummy", 5); |
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} |
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/* ------------------------------------------------------------------------ */ |
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/* |
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* Receive an AX.25 frame via an ethernet interface. |
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*/ |
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static int bpq_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *ptype, struct net_device *orig_dev) |
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{ |
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int len; |
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char * ptr; |
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struct ethhdr *eth; |
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struct bpqdev *bpq; |
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if (!net_eq(dev_net(dev), &init_net)) |
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goto drop; |
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if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) |
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return NET_RX_DROP; |
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if (!pskb_may_pull(skb, sizeof(struct ethhdr))) |
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goto drop; |
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rcu_read_lock(); |
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dev = bpq_get_ax25_dev(dev); |
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if (dev == NULL || !netif_running(dev)) |
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goto drop_unlock; |
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/* |
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* if we want to accept frames from just one ethernet device |
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* we check the source address of the sender. |
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*/ |
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bpq = netdev_priv(dev); |
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eth = eth_hdr(skb); |
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if (!(bpq->acpt_addr[0] & 0x01) && |
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!ether_addr_equal(eth->h_source, bpq->acpt_addr)) |
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goto drop_unlock; |
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if (skb_cow(skb, sizeof(struct ethhdr))) |
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goto drop_unlock; |
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len = skb->data[0] + skb->data[1] * 256 - 5; |
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skb_pull(skb, 2); /* Remove the length bytes */ |
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skb_trim(skb, len); /* Set the length of the data */ |
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dev->stats.rx_packets++; |
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dev->stats.rx_bytes += len; |
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ptr = skb_push(skb, 1); |
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*ptr = 0; |
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skb->protocol = ax25_type_trans(skb, dev); |
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netif_rx(skb); |
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unlock: |
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rcu_read_unlock(); |
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return 0; |
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drop_unlock: |
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kfree_skb(skb); |
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goto unlock; |
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drop: |
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kfree_skb(skb); |
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return 0; |
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} |
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/* |
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* Send an AX.25 frame via an ethernet interface |
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*/ |
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static netdev_tx_t bpq_xmit(struct sk_buff *skb, struct net_device *dev) |
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{ |
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unsigned char *ptr; |
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struct bpqdev *bpq; |
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struct net_device *orig_dev; |
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int size; |
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if (skb->protocol == htons(ETH_P_IP)) |
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return ax25_ip_xmit(skb); |
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/* |
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* Just to be *really* sure not to send anything if the interface |
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* is down, the ethernet device may have gone. |
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*/ |
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if (!netif_running(dev)) { |
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kfree_skb(skb); |
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return NETDEV_TX_OK; |
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} |
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skb_pull(skb, 1); /* Drop KISS byte */ |
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size = skb->len; |
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/* |
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* We're about to mess with the skb which may still shared with the |
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* generic networking code so unshare and ensure it's got enough |
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* space for the BPQ headers. |
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*/ |
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if (skb_cow(skb, AX25_BPQ_HEADER_LEN)) { |
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if (net_ratelimit()) |
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pr_err("bpqether: out of memory\n"); |
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kfree_skb(skb); |
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return NETDEV_TX_OK; |
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} |
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ptr = skb_push(skb, 2); /* Make space for length */ |
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*ptr++ = (size + 5) % 256; |
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*ptr++ = (size + 5) / 256; |
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bpq = netdev_priv(dev); |
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orig_dev = dev; |
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if ((dev = bpq_get_ether_dev(dev)) == NULL) { |
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orig_dev->stats.tx_dropped++; |
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kfree_skb(skb); |
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return NETDEV_TX_OK; |
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} |
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skb->protocol = ax25_type_trans(skb, dev); |
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skb_reset_network_header(skb); |
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dev_hard_header(skb, dev, ETH_P_BPQ, bpq->dest_addr, NULL, 0); |
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dev->stats.tx_packets++; |
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dev->stats.tx_bytes+=skb->len; |
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dev_queue_xmit(skb); |
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netif_wake_queue(dev); |
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return NETDEV_TX_OK; |
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} |
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/* |
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* Set AX.25 callsign |
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*/ |
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static int bpq_set_mac_address(struct net_device *dev, void *addr) |
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{ |
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struct sockaddr *sa = (struct sockaddr *)addr; |
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memcpy(dev->dev_addr, sa->sa_data, dev->addr_len); |
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return 0; |
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} |
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/* Ioctl commands |
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* |
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* SIOCSBPQETHOPT reserved for enhancements |
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* SIOCSBPQETHADDR set the destination and accepted |
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* source ethernet address (broadcast |
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* or multicast: accept all) |
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*/ |
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static int bpq_siocdevprivate(struct net_device *dev, struct ifreq *ifr, |
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void __user *data, int cmd) |
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{ |
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struct bpq_ethaddr __user *ethaddr = data; |
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struct bpqdev *bpq = netdev_priv(dev); |
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struct bpq_req req; |
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if (!capable(CAP_NET_ADMIN)) |
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return -EPERM; |
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switch (cmd) { |
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case SIOCSBPQETHOPT: |
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if (copy_from_user(&req, data, sizeof(struct bpq_req))) |
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return -EFAULT; |
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switch (req.cmd) { |
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case SIOCGBPQETHPARAM: |
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case SIOCSBPQETHPARAM: |
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default: |
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return -EINVAL; |
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} |
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break; |
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case SIOCSBPQETHADDR: |
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if (copy_from_user(bpq->dest_addr, ethaddr->destination, ETH_ALEN)) |
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return -EFAULT; |
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if (copy_from_user(bpq->acpt_addr, ethaddr->accept, ETH_ALEN)) |
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return -EFAULT; |
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break; |
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default: |
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return -EINVAL; |
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} |
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return 0; |
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} |
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/* |
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* open/close a device |
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*/ |
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static int bpq_open(struct net_device *dev) |
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{ |
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netif_start_queue(dev); |
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return 0; |
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} |
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static int bpq_close(struct net_device *dev) |
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{ |
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netif_stop_queue(dev); |
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return 0; |
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} |
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/* ------------------------------------------------------------------------ */ |
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#ifdef CONFIG_PROC_FS |
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/* |
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* Proc filesystem |
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*/ |
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static void *bpq_seq_start(struct seq_file *seq, loff_t *pos) |
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__acquires(RCU) |
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{ |
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int i = 1; |
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struct bpqdev *bpqdev; |
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rcu_read_lock(); |
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if (*pos == 0) |
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return SEQ_START_TOKEN; |
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list_for_each_entry_rcu(bpqdev, &bpq_devices, bpq_list) { |
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if (i == *pos) |
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return bpqdev; |
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} |
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return NULL; |
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} |
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static void *bpq_seq_next(struct seq_file *seq, void *v, loff_t *pos) |
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{ |
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struct list_head *p; |
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struct bpqdev *bpqdev = v; |
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++*pos; |
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if (v == SEQ_START_TOKEN) |
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p = rcu_dereference(list_next_rcu(&bpq_devices)); |
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else |
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p = rcu_dereference(list_next_rcu(&bpqdev->bpq_list)); |
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return (p == &bpq_devices) ? NULL |
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: list_entry(p, struct bpqdev, bpq_list); |
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} |
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static void bpq_seq_stop(struct seq_file *seq, void *v) |
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__releases(RCU) |
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{ |
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rcu_read_unlock(); |
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} |
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static int bpq_seq_show(struct seq_file *seq, void *v) |
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{ |
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if (v == SEQ_START_TOKEN) |
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seq_puts(seq, |
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"dev ether destination accept from\n"); |
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else { |
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const struct bpqdev *bpqdev = v; |
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seq_printf(seq, "%-5s %-10s %pM ", |
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bpqdev->axdev->name, bpqdev->ethdev->name, |
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bpqdev->dest_addr); |
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if (is_multicast_ether_addr(bpqdev->acpt_addr)) |
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seq_printf(seq, "*\n"); |
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else |
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seq_printf(seq, "%pM\n", bpqdev->acpt_addr); |
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} |
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return 0; |
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} |
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static const struct seq_operations bpq_seqops = { |
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.start = bpq_seq_start, |
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.next = bpq_seq_next, |
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.stop = bpq_seq_stop, |
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.show = bpq_seq_show, |
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}; |
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#endif |
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/* ------------------------------------------------------------------------ */ |
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static const struct net_device_ops bpq_netdev_ops = { |
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.ndo_open = bpq_open, |
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.ndo_stop = bpq_close, |
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.ndo_start_xmit = bpq_xmit, |
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.ndo_set_mac_address = bpq_set_mac_address, |
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.ndo_siocdevprivate = bpq_siocdevprivate, |
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}; |
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static void bpq_setup(struct net_device *dev) |
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{ |
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dev->netdev_ops = &bpq_netdev_ops; |
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dev->needs_free_netdev = true; |
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memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN); |
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memcpy(dev->dev_addr, &ax25_defaddr, AX25_ADDR_LEN); |
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dev->flags = 0; |
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dev->features = NETIF_F_LLTX; /* Allow recursion */ |
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#if IS_ENABLED(CONFIG_AX25) |
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dev->header_ops = &ax25_header_ops; |
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#endif |
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dev->type = ARPHRD_AX25; |
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dev->hard_header_len = AX25_MAX_HEADER_LEN + AX25_BPQ_HEADER_LEN; |
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dev->mtu = AX25_DEF_PACLEN; |
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dev->addr_len = AX25_ADDR_LEN; |
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} |
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/* |
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* Setup a new device. |
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*/ |
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static int bpq_new_device(struct net_device *edev) |
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{ |
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int err; |
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struct net_device *ndev; |
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struct bpqdev *bpq; |
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ndev = alloc_netdev(sizeof(struct bpqdev), "bpq%d", NET_NAME_UNKNOWN, |
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bpq_setup); |
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if (!ndev) |
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return -ENOMEM; |
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bpq = netdev_priv(ndev); |
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dev_hold(edev); |
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bpq->ethdev = edev; |
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bpq->axdev = ndev; |
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eth_broadcast_addr(bpq->dest_addr); |
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eth_broadcast_addr(bpq->acpt_addr); |
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err = register_netdevice(ndev); |
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if (err) |
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goto error; |
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bpq_set_lockdep_class(ndev); |
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/* List protected by RTNL */ |
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list_add_rcu(&bpq->bpq_list, &bpq_devices); |
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return 0; |
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error: |
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dev_put(edev); |
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free_netdev(ndev); |
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return err; |
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} |
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static void bpq_free_device(struct net_device *ndev) |
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{ |
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struct bpqdev *bpq = netdev_priv(ndev); |
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dev_put(bpq->ethdev); |
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list_del_rcu(&bpq->bpq_list); |
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unregister_netdevice(ndev); |
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} |
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/* |
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* Handle device status changes. |
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*/ |
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static int bpq_device_event(struct notifier_block *this, |
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unsigned long event, void *ptr) |
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{ |
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struct net_device *dev = netdev_notifier_info_to_dev(ptr); |
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if (!net_eq(dev_net(dev), &init_net)) |
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return NOTIFY_DONE; |
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if (!dev_is_ethdev(dev)) |
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return NOTIFY_DONE; |
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switch (event) { |
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case NETDEV_UP: /* new ethernet device -> new BPQ interface */ |
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if (bpq_get_ax25_dev(dev) == NULL) |
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bpq_new_device(dev); |
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break; |
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case NETDEV_DOWN: /* ethernet device closed -> close BPQ interface */ |
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if ((dev = bpq_get_ax25_dev(dev)) != NULL) |
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dev_close(dev); |
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break; |
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case NETDEV_UNREGISTER: /* ethernet device removed -> free BPQ interface */ |
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if ((dev = bpq_get_ax25_dev(dev)) != NULL) |
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bpq_free_device(dev); |
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break; |
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default: |
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break; |
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} |
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return NOTIFY_DONE; |
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} |
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/* ------------------------------------------------------------------------ */ |
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/* |
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* Initialize driver. To be called from af_ax25 if not compiled as a |
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* module |
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*/ |
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static int __init bpq_init_driver(void) |
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{ |
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#ifdef CONFIG_PROC_FS |
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if (!proc_create_seq("bpqether", 0444, init_net.proc_net, &bpq_seqops)) { |
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printk(KERN_ERR |
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"bpq: cannot create /proc/net/bpqether entry.\n"); |
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return -ENOENT; |
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} |
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#endif /* CONFIG_PROC_FS */ |
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dev_add_pack(&bpq_packet_type); |
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register_netdevice_notifier(&bpq_dev_notifier); |
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printk(banner); |
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return 0; |
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} |
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static void __exit bpq_cleanup_driver(void) |
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{ |
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struct bpqdev *bpq; |
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dev_remove_pack(&bpq_packet_type); |
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unregister_netdevice_notifier(&bpq_dev_notifier); |
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remove_proc_entry("bpqether", init_net.proc_net); |
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rtnl_lock(); |
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while (!list_empty(&bpq_devices)) { |
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bpq = list_entry(bpq_devices.next, struct bpqdev, bpq_list); |
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bpq_free_device(bpq->axdev); |
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} |
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rtnl_unlock(); |
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} |
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MODULE_AUTHOR("Joerg Reuter DL1BKE <[email protected]>"); |
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MODULE_DESCRIPTION("Transmit and receive AX.25 packets over Ethernet"); |
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MODULE_LICENSE("GPL"); |
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module_init(bpq_init_driver); |
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module_exit(bpq_cleanup_driver);
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