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![Xie He](/assets/img/avatar_default.png)
According to the X.25 documentation, there was a plan to implement X.25-over-802.2-LLC. It never finished but left various code stubs in the X.25 code. At this time it is unlikely that it would ever finish so it may be better to remove those code stubs. Also change the documentation to make it clear that this is not a ongoing plan anymore. Change words like "will" to "could", "would", etc. Cc: Martin Schiller <ms@dev.tdt.de> Signed-off-by: Xie He <xie.he.0141@gmail.com> Link: https://lore.kernel.org/r/20201209033346.83742-1-xie.he.0141@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
216 lines
4 KiB
C
216 lines
4 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* X.25 Packet Layer release 002
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*
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* This is ALPHA test software. This code may break your machine, randomly fail to work with new
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* releases, misbehave and/or generally screw up. It might even work.
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*
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* This code REQUIRES 2.1.15 or higher
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*
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* History
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* X.25 001 Jonathan Naylor Started coding.
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* 2000-09-04 Henner Eisen Prevent freeing a dangling skb.
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*/
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#define pr_fmt(fmt) "X25: " fmt
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#include <linux/kernel.h>
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#include <linux/netdevice.h>
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#include <linux/skbuff.h>
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#include <linux/slab.h>
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#include <net/sock.h>
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#include <linux/if_arp.h>
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#include <net/x25.h>
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#include <net/x25device.h>
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static int x25_receive_data(struct sk_buff *skb, struct x25_neigh *nb)
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{
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struct sock *sk;
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unsigned short frametype;
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unsigned int lci;
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if (!pskb_may_pull(skb, X25_STD_MIN_LEN))
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return 0;
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frametype = skb->data[2];
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lci = ((skb->data[0] << 8) & 0xF00) + ((skb->data[1] << 0) & 0x0FF);
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/*
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* LCI of zero is always for us, and its always a link control
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* frame.
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*/
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if (lci == 0) {
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x25_link_control(skb, nb, frametype);
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return 0;
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}
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/*
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* Find an existing socket.
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*/
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if ((sk = x25_find_socket(lci, nb)) != NULL) {
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int queued = 1;
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skb_reset_transport_header(skb);
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bh_lock_sock(sk);
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if (!sock_owned_by_user(sk)) {
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queued = x25_process_rx_frame(sk, skb);
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} else {
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queued = !sk_add_backlog(sk, skb, READ_ONCE(sk->sk_rcvbuf));
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}
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bh_unlock_sock(sk);
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sock_put(sk);
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return queued;
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}
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/*
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* Is is a Call Request ? if so process it.
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*/
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if (frametype == X25_CALL_REQUEST)
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return x25_rx_call_request(skb, nb, lci);
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/*
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* Its not a Call Request, nor is it a control frame.
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* Can we forward it?
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*/
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if (x25_forward_data(lci, nb, skb)) {
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if (frametype == X25_CLEAR_CONFIRMATION) {
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x25_clear_forward_by_lci(lci);
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}
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kfree_skb(skb);
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return 1;
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}
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/*
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x25_transmit_clear_request(nb, lci, 0x0D);
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*/
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if (frametype != X25_CLEAR_CONFIRMATION)
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pr_debug("x25_receive_data(): unknown frame type %2x\n",frametype);
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return 0;
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}
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int x25_lapb_receive_frame(struct sk_buff *skb, struct net_device *dev,
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struct packet_type *ptype, struct net_device *orig_dev)
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{
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struct sk_buff *nskb;
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struct x25_neigh *nb;
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if (!net_eq(dev_net(dev), &init_net))
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goto drop;
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nskb = skb_copy(skb, GFP_ATOMIC);
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if (!nskb)
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goto drop;
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kfree_skb(skb);
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skb = nskb;
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/*
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* Packet received from unrecognised device, throw it away.
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*/
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nb = x25_get_neigh(dev);
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if (!nb) {
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pr_debug("unknown neighbour - %s\n", dev->name);
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goto drop;
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}
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if (!pskb_may_pull(skb, 1)) {
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x25_neigh_put(nb);
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return 0;
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}
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switch (skb->data[0]) {
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case X25_IFACE_DATA:
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skb_pull(skb, 1);
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if (x25_receive_data(skb, nb)) {
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x25_neigh_put(nb);
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goto out;
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}
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break;
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case X25_IFACE_CONNECT:
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x25_link_established(nb);
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break;
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case X25_IFACE_DISCONNECT:
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x25_link_terminated(nb);
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break;
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}
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x25_neigh_put(nb);
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drop:
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kfree_skb(skb);
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out:
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return 0;
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}
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void x25_establish_link(struct x25_neigh *nb)
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{
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struct sk_buff *skb;
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unsigned char *ptr;
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switch (nb->dev->type) {
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case ARPHRD_X25:
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if ((skb = alloc_skb(1, GFP_ATOMIC)) == NULL) {
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pr_err("x25_dev: out of memory\n");
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return;
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}
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ptr = skb_put(skb, 1);
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*ptr = X25_IFACE_CONNECT;
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break;
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default:
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return;
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}
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skb->protocol = htons(ETH_P_X25);
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skb->dev = nb->dev;
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dev_queue_xmit(skb);
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}
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void x25_terminate_link(struct x25_neigh *nb)
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{
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struct sk_buff *skb;
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unsigned char *ptr;
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if (nb->dev->type != ARPHRD_X25)
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return;
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skb = alloc_skb(1, GFP_ATOMIC);
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if (!skb) {
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pr_err("x25_dev: out of memory\n");
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return;
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}
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ptr = skb_put(skb, 1);
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*ptr = X25_IFACE_DISCONNECT;
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skb->protocol = htons(ETH_P_X25);
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skb->dev = nb->dev;
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dev_queue_xmit(skb);
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}
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void x25_send_frame(struct sk_buff *skb, struct x25_neigh *nb)
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{
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unsigned char *dptr;
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skb_reset_network_header(skb);
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switch (nb->dev->type) {
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case ARPHRD_X25:
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dptr = skb_push(skb, 1);
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*dptr = X25_IFACE_DATA;
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break;
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default:
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kfree_skb(skb);
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return;
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}
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skb->protocol = htons(ETH_P_X25);
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skb->dev = nb->dev;
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dev_queue_xmit(skb);
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}
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