![Willem de Bruijn](/assets/img/avatar_default.png)
As variable length protocol, AX25 fails link layer header validation tests based on a minimum length. header_ops.validate allows protocols to validate headers that are shorter than hard_header_len. Implement this callback for AX25. See also http://comments.gmane.org/gmane.linux.network/401064 Signed-off-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
253 lines
5.5 KiB
C
253 lines
5.5 KiB
C
/*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
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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/module.h>
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#include <linux/timer.h>
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#include <linux/string.h>
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#include <linux/sockios.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/if_arp.h>
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#include <linux/skbuff.h>
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#include <net/sock.h>
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#include <asm/uaccess.h>
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#include <linux/fcntl.h>
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#include <linux/termios.h> /* For TIOCINQ/OUTQ */
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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/stat.h>
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#include <linux/sysctl.h>
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#include <net/ip.h>
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#include <net/arp.h>
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/*
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* IP over AX.25 encapsulation.
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*/
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/*
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* Shove an AX.25 UI header on an IP packet and handle ARP
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*/
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#ifdef CONFIG_INET
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static int ax25_hard_header(struct sk_buff *skb, struct net_device *dev,
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unsigned short type, const void *daddr,
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const void *saddr, unsigned int len)
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{
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unsigned char *buff;
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/* they sometimes come back to us... */
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if (type == ETH_P_AX25)
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return 0;
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/* header is an AX.25 UI frame from us to them */
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buff = skb_push(skb, AX25_HEADER_LEN);
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*buff++ = 0x00; /* KISS DATA */
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if (daddr != NULL)
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memcpy(buff, daddr, dev->addr_len); /* Address specified */
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buff[6] &= ~AX25_CBIT;
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buff[6] &= ~AX25_EBIT;
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buff[6] |= AX25_SSSID_SPARE;
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buff += AX25_ADDR_LEN;
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if (saddr != NULL)
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memcpy(buff, saddr, dev->addr_len);
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else
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memcpy(buff, dev->dev_addr, dev->addr_len);
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buff[6] &= ~AX25_CBIT;
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buff[6] |= AX25_EBIT;
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buff[6] |= AX25_SSSID_SPARE;
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buff += AX25_ADDR_LEN;
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*buff++ = AX25_UI; /* UI */
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/* Append a suitable AX.25 PID */
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switch (type) {
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case ETH_P_IP:
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*buff++ = AX25_P_IP;
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break;
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case ETH_P_ARP:
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*buff++ = AX25_P_ARP;
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break;
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default:
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printk(KERN_ERR "AX.25: ax25_hard_header - wrong protocol type 0x%2.2x\n", type);
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*buff++ = 0;
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break;
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}
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if (daddr != NULL)
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return AX25_HEADER_LEN;
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return -AX25_HEADER_LEN; /* Unfinished header */
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}
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netdev_tx_t ax25_ip_xmit(struct sk_buff *skb)
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{
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struct sk_buff *ourskb;
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unsigned char *bp = skb->data;
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ax25_route *route;
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struct net_device *dev = NULL;
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ax25_address *src, *dst;
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ax25_digi *digipeat = NULL;
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ax25_dev *ax25_dev;
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ax25_cb *ax25;
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char ip_mode = ' ';
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dst = (ax25_address *)(bp + 1);
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src = (ax25_address *)(bp + 8);
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route = ax25_get_route(dst, NULL);
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if (route) {
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digipeat = route->digipeat;
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dev = route->dev;
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ip_mode = route->ip_mode;
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}
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if (dev == NULL)
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dev = skb->dev;
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if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL) {
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kfree_skb(skb);
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goto put;
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}
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if (bp[16] == AX25_P_IP) {
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if (ip_mode == 'V' || (ip_mode == ' ' && ax25_dev->values[AX25_VALUES_IPDEFMODE])) {
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/*
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* We copy the buffer and release the original thereby
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* keeping it straight
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*
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* Note: we report 1 back so the caller will
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* not feed the frame direct to the physical device
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* We don't want that to happen. (It won't be upset
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* as we have pulled the frame from the queue by
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* freeing it).
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*
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* NB: TCP modifies buffers that are still
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* on a device queue, thus we use skb_copy()
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* instead of using skb_clone() unless this
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* gets fixed.
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*/
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ax25_address src_c;
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ax25_address dst_c;
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if ((ourskb = skb_copy(skb, GFP_ATOMIC)) == NULL) {
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kfree_skb(skb);
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goto put;
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}
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if (skb->sk != NULL)
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skb_set_owner_w(ourskb, skb->sk);
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kfree_skb(skb);
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/* dl9sau: bugfix
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* after kfree_skb(), dst and src which were pointer
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* to bp which is part of skb->data would not be valid
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* anymore hope that after skb_pull(ourskb, ..) our
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* dsc_c and src_c will not become invalid
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*/
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bp = ourskb->data;
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dst_c = *(ax25_address *)(bp + 1);
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src_c = *(ax25_address *)(bp + 8);
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skb_pull(ourskb, AX25_HEADER_LEN - 1); /* Keep PID */
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skb_reset_network_header(ourskb);
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ax25=ax25_send_frame(
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ourskb,
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ax25_dev->values[AX25_VALUES_PACLEN],
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&src_c,
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&dst_c, digipeat, dev);
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if (ax25) {
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ax25_cb_put(ax25);
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}
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goto put;
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}
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}
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bp[7] &= ~AX25_CBIT;
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bp[7] &= ~AX25_EBIT;
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bp[7] |= AX25_SSSID_SPARE;
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bp[14] &= ~AX25_CBIT;
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bp[14] |= AX25_EBIT;
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bp[14] |= AX25_SSSID_SPARE;
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skb_pull(skb, AX25_KISS_HEADER_LEN);
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if (digipeat != NULL) {
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if ((ourskb = ax25_rt_build_path(skb, src, dst, route->digipeat)) == NULL) {
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kfree_skb(skb);
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goto put;
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}
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skb = ourskb;
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}
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ax25_queue_xmit(skb, dev);
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put:
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if (route)
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ax25_put_route(route);
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return NETDEV_TX_OK;
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}
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#else /* INET */
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static int ax25_hard_header(struct sk_buff *skb, struct net_device *dev,
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unsigned short type, const void *daddr,
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const void *saddr, unsigned int len)
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{
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return -AX25_HEADER_LEN;
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}
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netdev_tx_t ax25_ip_xmit(struct sk_buff *skb)
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{
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kfree_skb(skb);
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return NETDEV_TX_OK;
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}
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#endif
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static bool ax25_validate_header(const char *header, unsigned int len)
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{
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ax25_digi digi;
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if (!len)
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return false;
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if (header[0])
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return true;
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return ax25_addr_parse(header + 1, len - 1, NULL, NULL, &digi, NULL,
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NULL);
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}
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const struct header_ops ax25_header_ops = {
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.create = ax25_hard_header,
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.validate = ax25_validate_header,
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};
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EXPORT_SYMBOL(ax25_header_ops);
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EXPORT_SYMBOL(ax25_ip_xmit);
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