x25_dev.c 4.2 KB

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  1. // SPDX-License-Identifier: GPL-2.0-or-later
  2. /*
  3. * X.25 Packet Layer release 002
  4. *
  5. * This is ALPHA test software. This code may break your machine, randomly fail to work with new
  6. * releases, misbehave and/or generally screw up. It might even work.
  7. *
  8. * This code REQUIRES 2.1.15 or higher
  9. *
  10. * History
  11. * X.25 001 Jonathan Naylor Started coding.
  12. * 2000-09-04 Henner Eisen Prevent freeing a dangling skb.
  13. */
  14. #define pr_fmt(fmt) "X25: " fmt
  15. #include <linux/kernel.h>
  16. #include <linux/netdevice.h>
  17. #include <linux/skbuff.h>
  18. #include <linux/slab.h>
  19. #include <net/sock.h>
  20. #include <linux/if_arp.h>
  21. #include <net/x25.h>
  22. #include <net/x25device.h>
  23. static int x25_receive_data(struct sk_buff *skb, struct x25_neigh *nb)
  24. {
  25. struct sock *sk;
  26. unsigned short frametype;
  27. unsigned int lci;
  28. if (!pskb_may_pull(skb, X25_STD_MIN_LEN))
  29. return 0;
  30. frametype = skb->data[2];
  31. lci = ((skb->data[0] << 8) & 0xF00) + ((skb->data[1] << 0) & 0x0FF);
  32. /*
  33. * LCI of zero is always for us, and its always a link control
  34. * frame.
  35. */
  36. if (lci == 0) {
  37. x25_link_control(skb, nb, frametype);
  38. return 0;
  39. }
  40. /*
  41. * Find an existing socket.
  42. */
  43. if ((sk = x25_find_socket(lci, nb)) != NULL) {
  44. int queued = 1;
  45. skb_reset_transport_header(skb);
  46. bh_lock_sock(sk);
  47. if (!sock_owned_by_user(sk)) {
  48. queued = x25_process_rx_frame(sk, skb);
  49. } else {
  50. queued = !sk_add_backlog(sk, skb, READ_ONCE(sk->sk_rcvbuf));
  51. }
  52. bh_unlock_sock(sk);
  53. sock_put(sk);
  54. return queued;
  55. }
  56. /*
  57. * Is is a Call Request ? if so process it.
  58. */
  59. if (frametype == X25_CALL_REQUEST)
  60. return x25_rx_call_request(skb, nb, lci);
  61. /*
  62. * Its not a Call Request, nor is it a control frame.
  63. * Can we forward it?
  64. */
  65. if (x25_forward_data(lci, nb, skb)) {
  66. if (frametype == X25_CLEAR_CONFIRMATION) {
  67. x25_clear_forward_by_lci(lci);
  68. }
  69. kfree_skb(skb);
  70. return 1;
  71. }
  72. /*
  73. x25_transmit_clear_request(nb, lci, 0x0D);
  74. */
  75. if (frametype != X25_CLEAR_CONFIRMATION)
  76. pr_debug("x25_receive_data(): unknown frame type %2x\n",frametype);
  77. return 0;
  78. }
  79. int x25_lapb_receive_frame(struct sk_buff *skb, struct net_device *dev,
  80. struct packet_type *ptype, struct net_device *orig_dev)
  81. {
  82. struct sk_buff *nskb;
  83. struct x25_neigh *nb;
  84. if (!net_eq(dev_net(dev), &init_net))
  85. goto drop;
  86. nskb = skb_copy(skb, GFP_ATOMIC);
  87. if (!nskb)
  88. goto drop;
  89. kfree_skb(skb);
  90. skb = nskb;
  91. /*
  92. * Packet received from unrecognised device, throw it away.
  93. */
  94. nb = x25_get_neigh(dev);
  95. if (!nb) {
  96. pr_debug("unknown neighbour - %s\n", dev->name);
  97. goto drop;
  98. }
  99. if (!pskb_may_pull(skb, 1)) {
  100. x25_neigh_put(nb);
  101. return 0;
  102. }
  103. switch (skb->data[0]) {
  104. case X25_IFACE_DATA:
  105. skb_pull(skb, 1);
  106. if (x25_receive_data(skb, nb)) {
  107. x25_neigh_put(nb);
  108. goto out;
  109. }
  110. break;
  111. case X25_IFACE_CONNECT:
  112. x25_link_established(nb);
  113. break;
  114. case X25_IFACE_DISCONNECT:
  115. x25_link_terminated(nb);
  116. break;
  117. }
  118. x25_neigh_put(nb);
  119. drop:
  120. kfree_skb(skb);
  121. out:
  122. return 0;
  123. }
  124. void x25_establish_link(struct x25_neigh *nb)
  125. {
  126. struct sk_buff *skb;
  127. unsigned char *ptr;
  128. switch (nb->dev->type) {
  129. case ARPHRD_X25:
  130. if ((skb = alloc_skb(1, GFP_ATOMIC)) == NULL) {
  131. pr_err("x25_dev: out of memory\n");
  132. return;
  133. }
  134. ptr = skb_put(skb, 1);
  135. *ptr = X25_IFACE_CONNECT;
  136. break;
  137. #if IS_ENABLED(CONFIG_LLC)
  138. case ARPHRD_ETHER:
  139. return;
  140. #endif
  141. default:
  142. return;
  143. }
  144. skb->protocol = htons(ETH_P_X25);
  145. skb->dev = nb->dev;
  146. dev_queue_xmit(skb);
  147. }
  148. void x25_terminate_link(struct x25_neigh *nb)
  149. {
  150. struct sk_buff *skb;
  151. unsigned char *ptr;
  152. #if IS_ENABLED(CONFIG_LLC)
  153. if (nb->dev->type == ARPHRD_ETHER)
  154. return;
  155. #endif
  156. if (nb->dev->type != ARPHRD_X25)
  157. return;
  158. skb = alloc_skb(1, GFP_ATOMIC);
  159. if (!skb) {
  160. pr_err("x25_dev: out of memory\n");
  161. return;
  162. }
  163. ptr = skb_put(skb, 1);
  164. *ptr = X25_IFACE_DISCONNECT;
  165. skb->protocol = htons(ETH_P_X25);
  166. skb->dev = nb->dev;
  167. dev_queue_xmit(skb);
  168. }
  169. void x25_send_frame(struct sk_buff *skb, struct x25_neigh *nb)
  170. {
  171. unsigned char *dptr;
  172. skb_reset_network_header(skb);
  173. switch (nb->dev->type) {
  174. case ARPHRD_X25:
  175. dptr = skb_push(skb, 1);
  176. *dptr = X25_IFACE_DATA;
  177. break;
  178. #if IS_ENABLED(CONFIG_LLC)
  179. case ARPHRD_ETHER:
  180. kfree_skb(skb);
  181. return;
  182. #endif
  183. default:
  184. kfree_skb(skb);
  185. return;
  186. }
  187. skb->protocol = htons(ETH_P_X25);
  188. skb->dev = nb->dev;
  189. dev_queue_xmit(skb);
  190. }