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 dev_kfree_skb(s->current_rx_buf); 91 kfree(s); 92 93 return usbnet_cdc_unbind(dev, intf); 94 } 95 96 static int vl600_rx_fixup(struct usbnet *dev, struct sk_buff *skb) 97 { 98 struct vl600_frame_hdr *frame; 99 struct vl600_pkt_hdr *packet; 100 struct ethhdr *ethhdr; 101 int packet_len, count; 102 struct sk_buff *buf = skb; 103 struct sk_buff *clone; 104 struct vl600_state *s = dev->driver_priv; 105 106 /* Frame lengths are generally 4B multiplies but every couple of 107 * hours there's an odd number of bytes sized yet correct frame, 108 * so don't require this. */ 109 110 /* Allow a packet (or multiple packets batched together) to be 111 * split across many frames. We don't allow a new batch to 112 * begin in the same frame another one is ending however, and no 113 * leading or trailing pad bytes. */ 114 if (s->current_rx_buf) { 115 frame = (struct vl600_frame_hdr *) s->current_rx_buf->data; 116 if (skb->len + s->current_rx_buf->len > 117 le32_to_cpup(&frame->len)) { 118 netif_err(dev, ifup, dev->net, "Fragment too long\n"); 119 dev->net->stats.rx_length_errors++; 120 goto error; 121 } 122 123 buf = s->current_rx_buf; 124 skb_put_data(buf, skb->data, skb->len); 125 } else if (skb->len < 4) { 126 netif_err(dev, ifup, dev->net, "Frame too short\n"); 127 dev->net->stats.rx_length_errors++; 128 goto error; 129 } 130 131 frame = (struct vl600_frame_hdr *) buf->data; 132 /* Yes, check that frame->magic == 0x53544448 (or 0x44544d48), 133 * otherwise we may run out of memory w/a bad packet */ 134 if (ntohl(frame->magic) != 0x53544448 && 135 ntohl(frame->magic) != 0x44544d48) 136 goto error; 137 138 if (buf->len < sizeof(*frame) || 139 buf->len != le32_to_cpup(&frame->len)) { 140 /* Save this fragment for later assembly */ 141 if (s->current_rx_buf) 142 return 0; 143 144 s->current_rx_buf = skb_copy_expand(skb, 0, 145 le32_to_cpup(&frame->len), GFP_ATOMIC); 146 if (!s->current_rx_buf) 147 dev->net->stats.rx_errors++; 148 149 return 0; 150 } 151 152 count = le32_to_cpup(&frame->pkt_cnt); 153 154 skb_pull(buf, sizeof(*frame)); 155 156 while (count--) { 157 if (buf->len < sizeof(*packet)) { 158 netif_err(dev, ifup, dev->net, "Packet too short\n"); 159 goto error; 160 } 161 162 packet = (struct vl600_pkt_hdr *) buf->data; 163 packet_len = sizeof(*packet) + le32_to_cpup(&packet->len); 164 if (packet_len > buf->len) { 165 netif_err(dev, ifup, dev->net, 166 "Bad packet length stored in header\n"); 167 goto error; 168 } 169 170 /* Packet header is same size as the ethernet header 171 * (sizeof(*packet) == sizeof(*ethhdr)), additionally 172 * the h_proto field is in the same place so we just leave it 173 * alone and fill in the remaining fields. 174 */ 175 ethhdr = (struct ethhdr *) skb->data; 176 if (be16_to_cpup(ðhdr->h_proto) == ETH_P_ARP && 177 buf->len > 0x26) { 178 /* Copy the addresses from packet contents */ 179 memcpy(ethhdr->h_source, 180 &buf->data[sizeof(*ethhdr) + 0x8], 181 ETH_ALEN); 182 memcpy(ethhdr->h_dest, 183 &buf->data[sizeof(*ethhdr) + 0x12], 184 ETH_ALEN); 185 } else { 186 eth_zero_addr(ethhdr->h_source); 187 memcpy(ethhdr->h_dest, dev->net->dev_addr, ETH_ALEN); 188 189 /* Inbound IPv6 packets have an IPv4 ethertype (0x800) 190 * for some reason. Peek at the L3 header to check 191 * for IPv6 packets, and set the ethertype to IPv6 192 * (0x86dd) so Linux can understand it. 193 */ 194 if ((buf->data[sizeof(*ethhdr)] & 0xf0) == 0x60) 195 ethhdr->h_proto = htons(ETH_P_IPV6); 196 } 197 198 if (count) { 199 /* Not the last packet in this batch */ 200 clone = skb_clone(buf, GFP_ATOMIC); 201 if (!clone) 202 goto error; 203 204 skb_trim(clone, packet_len); 205 usbnet_skb_return(dev, clone); 206 207 skb_pull(buf, (packet_len + 3) & ~3); 208 } else { 209 skb_trim(buf, packet_len); 210 211 if (s->current_rx_buf) { 212 usbnet_skb_return(dev, buf); 213 s->current_rx_buf = NULL; 214 return 0; 215 } 216 217 return 1; 218 } 219 } 220 221 error: 222 if (s->current_rx_buf) { 223 dev_kfree_skb_any(s->current_rx_buf); 224 s->current_rx_buf = NULL; 225 } 226 dev->net->stats.rx_errors++; 227 return 0; 228 } 229 230 static struct sk_buff *vl600_tx_fixup(struct usbnet *dev, 231 struct sk_buff *skb, gfp_t flags) 232 { 233 struct sk_buff *ret; 234 struct vl600_frame_hdr *frame; 235 struct vl600_pkt_hdr *packet; 236 static uint32_t serial = 1; 237 int orig_len = skb->len - sizeof(struct ethhdr); 238 int full_len = (skb->len + sizeof(struct vl600_frame_hdr) + 3) & ~3; 239 240 frame = (struct vl600_frame_hdr *) skb->data; 241 if (skb->len > sizeof(*frame) && skb->len == le32_to_cpup(&frame->len)) 242 return skb; /* Already encapsulated? */ 243 244 if (skb->len < sizeof(struct ethhdr)) 245 /* Drop, device can only deal with ethernet packets */ 246 return NULL; 247 248 if (!skb_cloned(skb)) { 249 int headroom = skb_headroom(skb); 250 int tailroom = skb_tailroom(skb); 251 252 if (tailroom >= full_len - skb->len - sizeof(*frame) && 253 headroom >= sizeof(*frame)) 254 /* There's enough head and tail room */ 255 goto encapsulate; 256 257 if (headroom + tailroom + skb->len >= full_len) { 258 /* There's enough total room, just readjust */ 259 skb->data = memmove(skb->head + sizeof(*frame), 260 skb->data, skb->len); 261 skb_set_tail_pointer(skb, skb->len); 262 goto encapsulate; 263 } 264 } 265 266 /* Alloc a new skb with the required size */ 267 ret = skb_copy_expand(skb, sizeof(struct vl600_frame_hdr), full_len - 268 skb->len - sizeof(struct vl600_frame_hdr), flags); 269 dev_kfree_skb_any(skb); 270 if (!ret) 271 return ret; 272 skb = ret; 273 274 encapsulate: 275 /* Packet header is same size as ethernet packet header 276 * (sizeof(*packet) == sizeof(struct ethhdr)), additionally the 277 * h_proto field is in the same place so we just leave it alone and 278 * overwrite the remaining fields. 279 */ 280 packet = (struct vl600_pkt_hdr *) skb->data; 281 /* The VL600 wants IPv6 packets to have an IPv4 ethertype 282 * Since this modem only supports IPv4 and IPv6, just set all 283 * frames to 0x0800 (ETH_P_IP) 284 */ 285 packet->h_proto = htons(ETH_P_IP); 286 memset(&packet->dummy, 0, sizeof(packet->dummy)); 287 packet->len = cpu_to_le32(orig_len); 288 289 frame = skb_push(skb, sizeof(*frame)); 290 memset(frame, 0, sizeof(*frame)); 291 frame->len = cpu_to_le32(full_len); 292 frame->serial = cpu_to_le32(serial++); 293 frame->pkt_cnt = cpu_to_le32(1); 294 295 if (skb->len < full_len) /* Pad */ 296 skb_put(skb, full_len - skb->len); 297 298 return skb; 299 } 300 301 static const struct driver_info vl600_info = { 302 .description = "LG VL600 modem", 303 .flags = FLAG_RX_ASSEMBLE | FLAG_WWAN, 304 .bind = vl600_bind, 305 .unbind = vl600_unbind, 306 .status = usbnet_cdc_status, 307 .rx_fixup = vl600_rx_fixup, 308 .tx_fixup = vl600_tx_fixup, 309 }; 310 311 static const struct usb_device_id products[] = { 312 { 313 USB_DEVICE_AND_INTERFACE_INFO(0x1004, 0x61aa, USB_CLASS_COMM, 314 USB_CDC_SUBCLASS_ETHERNET, USB_CDC_PROTO_NONE), 315 .driver_info = (unsigned long) &vl600_info, 316 }, 317 {}, /* End */ 318 }; 319 MODULE_DEVICE_TABLE(usb, products); 320 321 static struct usb_driver lg_vl600_driver = { 322 .name = "lg-vl600", 323 .id_table = products, 324 .probe = usbnet_probe, 325 .disconnect = usbnet_disconnect, 326 .suspend = usbnet_suspend, 327 .resume = usbnet_resume, 328 .disable_hub_initiated_lpm = 1, 329 }; 330 331 module_usb_driver(lg_vl600_driver); 332 333 MODULE_AUTHOR("Anrzej Zaborowski"); 334 MODULE_DESCRIPTION("LG-VL600 modem's ethernet link"); 335 MODULE_LICENSE("GPL"); 336