1 /* 2 * X.25 Packet Layer release 002 3 * 4 * This is ALPHA test software. This code may break your machine, randomly fail to work with new 5 * releases, misbehave and/or generally screw up. It might even work. 6 * 7 * This code REQUIRES 2.1.15 or higher 8 * 9 * This module: 10 * This module is free software; you can redistribute it and/or 11 * modify it under the terms of the GNU General Public License 12 * as published by the Free Software Foundation; either version 13 * 2 of the License, or (at your option) any later version. 14 * 15 * History 16 * X.25 001 Jonathan Naylor Started coding. 17 * 2000-09-04 Henner Eisen Prevent freeing a dangling skb. 18 */ 19 20 #include <linux/kernel.h> 21 #include <linux/netdevice.h> 22 #include <linux/skbuff.h> 23 #include <linux/slab.h> 24 #include <net/sock.h> 25 #include <linux/if_arp.h> 26 #include <net/x25.h> 27 #include <net/x25device.h> 28 29 static int x25_receive_data(struct sk_buff *skb, struct x25_neigh *nb) 30 { 31 struct sock *sk; 32 unsigned short frametype; 33 unsigned int lci; 34 35 frametype = skb->data[2]; 36 lci = ((skb->data[0] << 8) & 0xF00) + ((skb->data[1] << 0) & 0x0FF); 37 38 /* 39 * LCI of zero is always for us, and its always a link control 40 * frame. 41 */ 42 if (lci == 0) { 43 x25_link_control(skb, nb, frametype); 44 return 0; 45 } 46 47 /* 48 * Find an existing socket. 49 */ 50 if ((sk = x25_find_socket(lci, nb)) != NULL) { 51 int queued = 1; 52 53 skb_reset_transport_header(skb); 54 bh_lock_sock(sk); 55 if (!sock_owned_by_user(sk)) { 56 queued = x25_process_rx_frame(sk, skb); 57 } else { 58 queued = !sk_add_backlog(sk, skb); 59 } 60 bh_unlock_sock(sk); 61 sock_put(sk); 62 return queued; 63 } 64 65 /* 66 * Is is a Call Request ? if so process it. 67 */ 68 if (frametype == X25_CALL_REQUEST) 69 return x25_rx_call_request(skb, nb, lci); 70 71 /* 72 * Its not a Call Request, nor is it a control frame. 73 * Can we forward it? 74 */ 75 76 if (x25_forward_data(lci, nb, skb)) { 77 if (frametype == X25_CLEAR_CONFIRMATION) { 78 x25_clear_forward_by_lci(lci); 79 } 80 kfree_skb(skb); 81 return 1; 82 } 83 84 /* 85 x25_transmit_clear_request(nb, lci, 0x0D); 86 */ 87 88 if (frametype != X25_CLEAR_CONFIRMATION) 89 printk(KERN_DEBUG "x25_receive_data(): unknown frame type %2x\n",frametype); 90 91 return 0; 92 } 93 94 int x25_lapb_receive_frame(struct sk_buff *skb, struct net_device *dev, 95 struct packet_type *ptype, struct net_device *orig_dev) 96 { 97 struct sk_buff *nskb; 98 struct x25_neigh *nb; 99 100 if (!net_eq(dev_net(dev), &init_net)) 101 goto drop; 102 103 nskb = skb_copy(skb, GFP_ATOMIC); 104 if (!nskb) 105 goto drop; 106 kfree_skb(skb); 107 skb = nskb; 108 109 /* 110 * Packet received from unrecognised device, throw it away. 111 */ 112 nb = x25_get_neigh(dev); 113 if (!nb) { 114 printk(KERN_DEBUG "X.25: unknown neighbour - %s\n", dev->name); 115 goto drop; 116 } 117 118 switch (skb->data[0]) { 119 120 case X25_IFACE_DATA: 121 skb_pull(skb, 1); 122 if (x25_receive_data(skb, nb)) { 123 x25_neigh_put(nb); 124 goto out; 125 } 126 break; 127 128 case X25_IFACE_CONNECT: 129 x25_link_established(nb); 130 break; 131 132 case X25_IFACE_DISCONNECT: 133 x25_link_terminated(nb); 134 break; 135 } 136 x25_neigh_put(nb); 137 drop: 138 kfree_skb(skb); 139 out: 140 return 0; 141 } 142 143 void x25_establish_link(struct x25_neigh *nb) 144 { 145 struct sk_buff *skb; 146 unsigned char *ptr; 147 148 switch (nb->dev->type) { 149 case ARPHRD_X25: 150 if ((skb = alloc_skb(1, GFP_ATOMIC)) == NULL) { 151 printk(KERN_ERR "x25_dev: out of memory\n"); 152 return; 153 } 154 ptr = skb_put(skb, 1); 155 *ptr = X25_IFACE_CONNECT; 156 break; 157 158 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE) 159 case ARPHRD_ETHER: 160 return; 161 #endif 162 default: 163 return; 164 } 165 166 skb->protocol = htons(ETH_P_X25); 167 skb->dev = nb->dev; 168 169 dev_queue_xmit(skb); 170 } 171 172 void x25_terminate_link(struct x25_neigh *nb) 173 { 174 struct sk_buff *skb; 175 unsigned char *ptr; 176 177 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE) 178 if (nb->dev->type == ARPHRD_ETHER) 179 return; 180 #endif 181 if (nb->dev->type != ARPHRD_X25) 182 return; 183 184 skb = alloc_skb(1, GFP_ATOMIC); 185 if (!skb) { 186 printk(KERN_ERR "x25_dev: out of memory\n"); 187 return; 188 } 189 190 ptr = skb_put(skb, 1); 191 *ptr = X25_IFACE_DISCONNECT; 192 193 skb->protocol = htons(ETH_P_X25); 194 skb->dev = nb->dev; 195 dev_queue_xmit(skb); 196 } 197 198 void x25_send_frame(struct sk_buff *skb, struct x25_neigh *nb) 199 { 200 unsigned char *dptr; 201 202 skb_reset_network_header(skb); 203 204 switch (nb->dev->type) { 205 case ARPHRD_X25: 206 dptr = skb_push(skb, 1); 207 *dptr = X25_IFACE_DATA; 208 break; 209 210 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE) 211 case ARPHRD_ETHER: 212 kfree_skb(skb); 213 return; 214 #endif 215 default: 216 kfree_skb(skb); 217 return; 218 } 219 220 skb->protocol = htons(ETH_P_X25); 221 skb->dev = nb->dev; 222 223 dev_queue_xmit(skb); 224 } 225