1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Ethernet interface part of the LG VL600 LTE modem (4G dongle) 4 * 5 * Copyright (C) 2011 Intel Corporation 6 * Author: Andrzej Zaborowski <balrogg@gmail.com> 7 */ 8 #include <linux/etherdevice.h> 9 #include <linux/ethtool.h> 10 #include <linux/mii.h> 11 #include <linux/usb.h> 12 #include <linux/usb/cdc.h> 13 #include <linux/usb/usbnet.h> 14 #include <linux/if_ether.h> 15 #include <linux/if_arp.h> 16 #include <linux/inetdevice.h> 17 #include <linux/module.h> 18 19 /* 20 * The device has a CDC ACM port for modem control (it claims to be 21 * CDC ACM anyway) and a CDC Ethernet port for actual network data. 22 * It will however ignore data on both ports that is not encapsulated 23 * in a specific way, any data returned is also encapsulated the same 24 * way. The headers don't seem to follow any popular standard. 25 * 26 * This driver adds and strips these headers from the ethernet frames 27 * sent/received from the CDC Ethernet port. The proprietary header 28 * replaces the standard ethernet header in a packet so only actual 29 * ethernet frames are allowed. The headers allow some form of 30 * multiplexing by using non standard values of the .h_proto field. 31 * Windows/Mac drivers do send a couple of such frames to the device 32 * during initialisation, with protocol set to 0x0906 or 0x0b06 and (what 33 * seems to be) a flag in the .dummy_flags. This doesn't seem necessary 34 * for modem operation but can possibly be used for GPS or other funcitons. 35 */ 36 37 struct vl600_frame_hdr { 38 __le32 len; 39 __le32 serial; 40 __le32 pkt_cnt; 41 __le32 dummy_flags; 42 __le32 dummy; 43 __le32 magic; 44 } __attribute__((packed)); 45 46 struct vl600_pkt_hdr { 47 __le32 dummy[2]; 48 __le32 len; 49 __be16 h_proto; 50 } __attribute__((packed)); 51 52 struct vl600_state { 53 struct sk_buff *current_rx_buf; 54 }; 55 56 static int vl600_bind(struct usbnet *dev, struct usb_interface *intf) 57 { 58 int ret; 59 struct vl600_state *s = kzalloc(sizeof(struct vl600_state), GFP_KERNEL); 60 61 if (!s) 62 return -ENOMEM; 63 64 ret = usbnet_cdc_bind(dev, intf); 65 if (ret) { 66 kfree(s); 67 return ret; 68 } 69 70 dev->driver_priv = s; 71 72 /* ARP packets don't go through, but they're also of no use. The 73 * subnet has only two hosts anyway: us and the gateway / DHCP 74 * server (probably simulated by modem firmware or network operator) 75 * whose address changes everytime we connect to the intarwebz and 76 * who doesn't bother answering ARP requests either. So hardware 77 * addresses have no meaning, the destination and the source of every 78 * packet depend only on whether it is on the IN or OUT endpoint. */ 79 dev->net->flags |= IFF_NOARP; 80 /* IPv6 NDP relies on multicast. Enable it by default. */ 81 dev->net->flags |= IFF_MULTICAST; 82 83 return ret; 84 } 85 86 static void vl600_unbind(struct usbnet *dev, struct usb_interface *intf) 87 { 88 struct vl600_state *s = dev->driver_priv; 89 90 if (s->current_rx_buf) 91 dev_kfree_skb(s->current_rx_buf); 92 93 kfree(s); 94 95 return usbnet_cdc_unbind(dev, intf); 96 } 97 98 static int vl600_rx_fixup(struct usbnet *dev, struct sk_buff *skb) 99 { 100 struct vl600_frame_hdr *frame; 101 struct vl600_pkt_hdr *packet; 102 struct ethhdr *ethhdr; 103 int packet_len, count; 104 struct sk_buff *buf = skb; 105 struct sk_buff *clone; 106 struct vl600_state *s = dev->driver_priv; 107 108 /* Frame lengths are generally 4B multiplies but every couple of 109 * hours there's an odd number of bytes sized yet correct frame, 110 * so don't require this. */ 111 112 /* Allow a packet (or multiple packets batched together) to be 113 * split across many frames. We don't allow a new batch to 114 * begin in the same frame another one is ending however, and no 115 * leading or trailing pad bytes. */ 116 if (s->current_rx_buf) { 117 frame = (struct vl600_frame_hdr *) s->current_rx_buf->data; 118 if (skb->len + s->current_rx_buf->len > 119 le32_to_cpup(&frame->len)) { 120 netif_err(dev, ifup, dev->net, "Fragment too long\n"); 121 dev->net->stats.rx_length_errors++; 122 goto error; 123 } 124 125 buf = s->current_rx_buf; 126 skb_put_data(buf, skb->data, skb->len); 127 } else if (skb->len < 4) { 128 netif_err(dev, ifup, dev->net, "Frame too short\n"); 129 dev->net->stats.rx_length_errors++; 130 goto error; 131 } 132 133 frame = (struct vl600_frame_hdr *) buf->data; 134 /* Yes, check that frame->magic == 0x53544448 (or 0x44544d48), 135 * otherwise we may run out of memory w/a bad packet */ 136 if (ntohl(frame->magic) != 0x53544448 && 137 ntohl(frame->magic) != 0x44544d48) 138 goto error; 139 140 if (buf->len < sizeof(*frame) || 141 buf->len != le32_to_cpup(&frame->len)) { 142 /* Save this fragment for later assembly */ 143 if (s->current_rx_buf) 144 return 0; 145 146 s->current_rx_buf = skb_copy_expand(skb, 0, 147 le32_to_cpup(&frame->len), GFP_ATOMIC); 148 if (!s->current_rx_buf) 149 dev->net->stats.rx_errors++; 150 151 return 0; 152 } 153 154 count = le32_to_cpup(&frame->pkt_cnt); 155 156 skb_pull(buf, sizeof(*frame)); 157 158 while (count--) { 159 if (buf->len < sizeof(*packet)) { 160 netif_err(dev, ifup, dev->net, "Packet too short\n"); 161 goto error; 162 } 163 164 packet = (struct vl600_pkt_hdr *) buf->data; 165 packet_len = sizeof(*packet) + le32_to_cpup(&packet->len); 166 if (packet_len > buf->len) { 167 netif_err(dev, ifup, dev->net, 168 "Bad packet length stored in header\n"); 169 goto error; 170 } 171 172 /* Packet header is same size as the ethernet header 173 * (sizeof(*packet) == sizeof(*ethhdr)), additionally 174 * the h_proto field is in the same place so we just leave it 175 * alone and fill in the remaining fields. 176 */ 177 ethhdr = (struct ethhdr *) skb->data; 178 if (be16_to_cpup(ðhdr->h_proto) == ETH_P_ARP && 179 buf->len > 0x26) { 180 /* Copy the addresses from packet contents */ 181 memcpy(ethhdr->h_source, 182 &buf->data[sizeof(*ethhdr) + 0x8], 183 ETH_ALEN); 184 memcpy(ethhdr->h_dest, 185 &buf->data[sizeof(*ethhdr) + 0x12], 186 ETH_ALEN); 187 } else { 188 eth_zero_addr(ethhdr->h_source); 189 memcpy(ethhdr->h_dest, dev->net->dev_addr, ETH_ALEN); 190 191 /* Inbound IPv6 packets have an IPv4 ethertype (0x800) 192 * for some reason. Peek at the L3 header to check 193 * for IPv6 packets, and set the ethertype to IPv6 194 * (0x86dd) so Linux can understand it. 195 */ 196 if ((buf->data[sizeof(*ethhdr)] & 0xf0) == 0x60) 197 ethhdr->h_proto = htons(ETH_P_IPV6); 198 } 199 200 if (count) { 201 /* Not the last packet in this batch */ 202 clone = skb_clone(buf, GFP_ATOMIC); 203 if (!clone) 204 goto error; 205 206 skb_trim(clone, packet_len); 207 usbnet_skb_return(dev, clone); 208 209 skb_pull(buf, (packet_len + 3) & ~3); 210 } else { 211 skb_trim(buf, packet_len); 212 213 if (s->current_rx_buf) { 214 usbnet_skb_return(dev, buf); 215 s->current_rx_buf = NULL; 216 return 0; 217 } 218 219 return 1; 220 } 221 } 222 223 error: 224 if (s->current_rx_buf) { 225 dev_kfree_skb_any(s->current_rx_buf); 226 s->current_rx_buf = NULL; 227 } 228 dev->net->stats.rx_errors++; 229 return 0; 230 } 231 232 static struct sk_buff *vl600_tx_fixup(struct usbnet *dev, 233 struct sk_buff *skb, gfp_t flags) 234 { 235 struct sk_buff *ret; 236 struct vl600_frame_hdr *frame; 237 struct vl600_pkt_hdr *packet; 238 static uint32_t serial = 1; 239 int orig_len = skb->len - sizeof(struct ethhdr); 240 int full_len = (skb->len + sizeof(struct vl600_frame_hdr) + 3) & ~3; 241 242 frame = (struct vl600_frame_hdr *) skb->data; 243 if (skb->len > sizeof(*frame) && skb->len == le32_to_cpup(&frame->len)) 244 return skb; /* Already encapsulated? */ 245 246 if (skb->len < sizeof(struct ethhdr)) 247 /* Drop, device can only deal with ethernet packets */ 248 return NULL; 249 250 if (!skb_cloned(skb)) { 251 int headroom = skb_headroom(skb); 252 int tailroom = skb_tailroom(skb); 253 254 if (tailroom >= full_len - skb->len - sizeof(*frame) && 255 headroom >= sizeof(*frame)) 256 /* There's enough head and tail room */ 257 goto encapsulate; 258 259 if (headroom + tailroom + skb->len >= full_len) { 260 /* There's enough total room, just readjust */ 261 skb->data = memmove(skb->head + sizeof(*frame), 262 skb->data, skb->len); 263 skb_set_tail_pointer(skb, skb->len); 264 goto encapsulate; 265 } 266 } 267 268 /* Alloc a new skb with the required size */ 269 ret = skb_copy_expand(skb, sizeof(struct vl600_frame_hdr), full_len - 270 skb->len - sizeof(struct vl600_frame_hdr), flags); 271 dev_kfree_skb_any(skb); 272 if (!ret) 273 return ret; 274 skb = ret; 275 276 encapsulate: 277 /* Packet header is same size as ethernet packet header 278 * (sizeof(*packet) == sizeof(struct ethhdr)), additionally the 279 * h_proto field is in the same place so we just leave it alone and 280 * overwrite the remaining fields. 281 */ 282 packet = (struct vl600_pkt_hdr *) skb->data; 283 /* The VL600 wants IPv6 packets to have an IPv4 ethertype 284 * Since this modem only supports IPv4 and IPv6, just set all 285 * frames to 0x0800 (ETH_P_IP) 286 */ 287 packet->h_proto = htons(ETH_P_IP); 288 memset(&packet->dummy, 0, sizeof(packet->dummy)); 289 packet->len = cpu_to_le32(orig_len); 290 291 frame = skb_push(skb, sizeof(*frame)); 292 memset(frame, 0, sizeof(*frame)); 293 frame->len = cpu_to_le32(full_len); 294 frame->serial = cpu_to_le32(serial++); 295 frame->pkt_cnt = cpu_to_le32(1); 296 297 if (skb->len < full_len) /* Pad */ 298 skb_put(skb, full_len - skb->len); 299 300 return skb; 301 } 302 303 static const struct driver_info vl600_info = { 304 .description = "LG VL600 modem", 305 .flags = FLAG_RX_ASSEMBLE | FLAG_WWAN, 306 .bind = vl600_bind, 307 .unbind = vl600_unbind, 308 .status = usbnet_cdc_status, 309 .rx_fixup = vl600_rx_fixup, 310 .tx_fixup = vl600_tx_fixup, 311 }; 312 313 static const struct usb_device_id products[] = { 314 { 315 USB_DEVICE_AND_INTERFACE_INFO(0x1004, 0x61aa, USB_CLASS_COMM, 316 USB_CDC_SUBCLASS_ETHERNET, USB_CDC_PROTO_NONE), 317 .driver_info = (unsigned long) &vl600_info, 318 }, 319 {}, /* End */ 320 }; 321 MODULE_DEVICE_TABLE(usb, products); 322 323 static struct usb_driver lg_vl600_driver = { 324 .name = "lg-vl600", 325 .id_table = products, 326 .probe = usbnet_probe, 327 .disconnect = usbnet_disconnect, 328 .suspend = usbnet_suspend, 329 .resume = usbnet_resume, 330 .disable_hub_initiated_lpm = 1, 331 }; 332 333 module_usb_driver(lg_vl600_driver); 334 335 MODULE_AUTHOR("Anrzej Zaborowski"); 336 MODULE_DESCRIPTION("LG-VL600 modem's ethernet link"); 337 MODULE_LICENSE("GPL"); 338